To compare posterior tibial slope (PTS) measurements of the medial tibial plateau (MTP) and lateral tibial plateau (LTP) on magnetic resonance imaging (MRI) versus computed tomography (CT) to determine the agreement of measurement between imaging modalities.

Patients aged 15 to 65 years with concurrent MRI and CT imaging were initially included. Knees with significant arthrosis (Kellgren-Lawrence grade >2), proximal tibia fracture, or artifact obscuring visualization were excluded. Two independent raters measured PTS of the MTP and LTP on paired MRI and CT. Inter- and intrarater reliability were assessed using the intraclass correlation coefficient (ICC). Intermethod agreement was assessed using ICC and Bland-Altman analyses. An acceptable Bland-Altman limit of agreement (LOA) was set at ±2°, requiring 95% of measurement differences between imaging modalities to fall between ±2° for an acceptable level of agreement.

Forty-six knees in 45 patients met final inclusion criteria. Inter-rater reliability was good for MRI (ICC 0.78-0.83) and moderate to good for CT (ICC 0.64-0.80) studies. Intrarater reliability was moderate to excellent (ICC 0.64-0.94). Intermethod agreement between MRI and CT was poor at the MTP (ICC 0.34-0.42) and moderate at the LTP (ICC 0.59-0.70). Bland-Altman analysis demonstrated high variability of PTS measurements between MRI and CT: 0.16° (95% LOA -6.10° to 6.41°) for MTP for Rater 1; 0.22° (95% LOA -5.01° to 5.45°) for LTP for rater 1; -0.95° (95% LOA -7.22° to 5.33°) for MTP for Rater 2; -0.99° (95% LOA -6.48° to 4.85°) for LTP for rater 2, with only 47.83% to 60.87% of measurement differences falling within the predetermined acceptable LOA of ±2°.

Although the inter- and intrarater reliability was moderate to excellent, the degree of agreement between PTS measurements on MRI and CT was highly variable at both medial and lateral plateaus. Although some variability may have been due to the study's limitations, PTS measurements at individual plateaus may not be interchangeable between MRI and CT.

Level III, retrospective cohort study.

Anterior cruciate ligament tears represent a prevalent injury in sports that involves rotational movements and rapid changes in direction, such as pivot-contact sports. The anterior cruciate ligament serves as the primary stabilizer of the knee, preventing anterior tibial translation and medial tibial rotation. Although clinical examination is essential for diagnosis, magnetic resonance imaging plays a crucial role in confirming complete tears and evaluating associated injuries, particularly meniscal injuries. Diagnosis relies on both direct and secondary signs that are instrumental in assessing knee laxity and stability. Despite advancements in imaging techniques, challenges persist in using magnetic resonance imaging to distinguish between complete and partial tears, evaluate knee instability, and determine the potential for anterior cruciate ligament healing.

A steep posterior tibial slope (PTS) and excessive anterior tibial subluxation of the lateral compartment (ASLC) have been considered to be associated with inferior graft outcomes in primary anterior cruciate ligament (ACL) reconstruction (ACLR). Case series studies have demonstrated that combined slope-reducing tibial osteotomy can greatly improve knee functional scores and stability in revision ACLR. However, there is currently no comparative study evaluating the clinical benefits of osteotomy procedures in primary ACLR.

To assess the feasibility of combined slope-reducing tibial osteotomy and primary ACLR in patients with a steep PTS and excessive ASLC and to explore the suitable threshold for osteotomy.

Case series; Level of evidence, 4.

Between 2016 and 2022, of the 108 patients with ACL injuries who had a steep PTS (≥15°) and a follow-up ≥2 years, 30 patients with excessive ASLC (≥6 mm) underwent concomitant slope-reducing tibial osteotomy and ACLR (osteotomy group), and 78 patients underwent isolated ACLR (control group). Propensity score matching at a 1:2 ratio was used to match preoperative variables between the 2 groups. After matching preoperative variables, 25 and 48 patients underwent combined surgery and isolated ACLR, respectively. The primary outcome was ACL graft status (failure and laxity rates). The secondary outcomes were ASLC and anterior tibial subluxation of the medial compartment (ASMC), KT-1000 arthrometer side-to-side difference (SSD), pivot-shift grade, and second-look arthroscopic findings. Stratified analysis was performed with 1° PTS increments to explore the osteotomy threshold.

Both groups were comparable in terms of age, sex, side, body mass index, PTS, graft diameter, time from injury to surgery, ASLC, ASMC, KT-1000 arthrometer SSD, pivot-shift grade, and meniscal injuries (all P > .05). The mean PTS significantly decreased from 18.2° to 6.7° (P < .001) in the osteotomy group. The 2-year rate of ACL graft laxity was 12.0% in the osteotomy group and 35.4% in the control group, with a statistically significant difference (P = .033). There was no significant difference in the 2-year rate of ACL graft failure between the 2 groups (8.0% vs 12.5%, respectively; P = .559). The final follow-up data showed that improvements in ASLC (4.5 vs 6.4 mm, respectively; P = .012) and ASMC (2.8 vs 4.5 mm, respectively; P = .014) were more significant in the osteotomy group compared with the control group. On the second-look arthroscopic examination, the incidence of graft roof impingement in the control group was significantly higher than that in the osteotomy group (22.9% vs 4.0%, respectively; P = .039). No significant differences were observed between the 2 groups in terms of KT-1000 arthrometer SSD and high-grade pivot shift (P > .05). Furthermore, stratified analysis revealed that the combined procedure significantly reduced the ACL graft failure rate and improved the KT-1000 arthrometer SSD in patients with a preoperative PTS ≥16°.

Slope-reducing tibial osteotomy combined with primary ACLR significantly decreased the amount of anterior tibial subluxation, the incidence of graft roof impingement, and the graft laxity rate for patients with a steep PTS (≥15°) and excessive ASLC (≥6 mm). Furthermore, in patients with a PTS ≥16°, the combined procedure improved anterior knee stability and reduced the graft failure rate. Therefore, a PTS ≥16° plus ASLC ≥6 mm may be considered an appropriate indication for combining slope-reducing tibial osteotomy with primary ACLR.

Multiple techniques have been utilized to measure posterior tibial slope (PTS) without consensus on which imaging modality, view, and axis combination is most consistent for risk assessment and preoperative planning in primary and revision anterior cruciate ligament (ACL) surgery. An exclusively proximal-based measurement of PTS has yet to be defined.

The purpose of this study was to establish normal values for novel measurements of sagittal proximal tibial morphology, the lateral supratubercle angle (LSTA) and the lateral supratubercle distance (LSTD), in normative and primary ACL tear cohorts. The secondary aim was to establish cutoff values and determine if these tibial measurement values are predictive of the presence of an ACL tear. It was hypothesized that LSTA will be significantly different between cohorts.

Case-control study; Level of evidence, 3.

The medical records of patients with a knee complaint between August 2016 and June 2024 were retrospectively reviewed, and the patients were placed into either the normative or primary ACL tear cohort. Three independent observers measured LSTA, LSTD, and PTS along both the lateral (L) and medial (M) tibial plateaus on standard lateral knee radiographs. Means were calculated for each measurement and compared between groups. The receiver operating characteristic curve was used to determine the sensitivity and specificity of significant measurements.

Significant differences were found between normative (n = 150) and primary ACL tear (n = 150) groups in LSTA-L (normative: 9.9°± 4.4° vs primary ACL tear: 11.1°± 4.4°; P = .02), LSTA-M (normative: 10.3°± 4.4° vs ACL tear: 11.4°± 4.6°; P = .03), and PTS-M (normative: 9.2°± 3.2° vs primary ACL tear: 10.0°± 3.1°; P = .03).

Mean values and ranges for LSTA and LSTD have been established in normative and primary ACL tear cohorts. LSTA-L, LSTA-M, and PTS-M significantly differed between the cohorts. Future studies with LSTA will evaluate the utilization of these proximal tibial deformity-based measurements in ACL surgery, retear risk assessment, and slope-reducing osteotomy planning.

Sagittal-plane slope-reducing high tibial osteotomy (HTO) can reduce the risk of anterior cruciate ligament (ACL) injury in knees with a high posterior tibial slope. The biomechanical effect of slope-reducing HTO on tibiofemoral kinematics and force carried by the ACL remains less well understood.

Decreased tibial slope will be associated with decreased ACL force, coupled internal tibial rotation (ITR), and anterior tibial translation (ATT) under both compressive and combined compressive and valgus loads.

Descriptive laboratory study.

Computational models of 10 cadaveric knees were created using magnetic resonance imaging- and computed tomography-based 3-dimensional renderings of the bones, articular cartilage, and menisci. Virtual slope-reducing HTO was performed on each tibial geometry in 1° increments, creating tibial slopes spanning -5° to 15°. All knees were flexed to 15°, and loads consisting of (1) axial compression (100 N) and (2) combined axial compression (100 N) and valgus torque (8 N·m) were then applied to each knee at each tibial slope. The outcome measures were ACL force, coupled ITR, and ATT. Relationships between tibial slope and each outcome measure were assessed via linear regression (α = .05), and the effects of 10° slope-reducing HTO, from 15° to 5°, on each outcome measure were reported.

A 10° slope-reducing HTO decreased ACL force by 53% under compression (1.7 N of ACL force per degree decrease in tibial slope; P < .001) and 47% under combined compression and valgus (4.7 N of ACL force per degree decrease in tibial slope; P < .001). Regarding kinematics, a 10° slope-reducing HTO decreased coupled ITR by 64% under combined compression and valgus (0.99° of coupled ITR per degree decrease in tibial slope; P < .001). Finally, a 10° slope-reducing HTO decreased ATT by 54% under compression (0.14 mm of ATT per degree decrease in tibial slope; P < .001).

Slope-reducing HTO decreased ACL force linearly by reducing ATT with compression and also by decreasing coupled ITR with combined compression and valgus.

Slope-reducing HTO decreased ATT and coupled ITR, dampening movements known to load the ACL. These findings may provide a further biomechanical basis for the ability of slope-reducing HTO to decrease the risk of ACL injury.

To (1) summarize indications/inclusion criteria and contraindications/exclusion criteria, operative techniques and details, and rehabilitation timelines for slope-reducing osteotomies with concomitant primary or revision anterior cruciate ligament (ACLR) and (2) summarize the radiographic and clinical outcomes that follow these types of surgeries.

Three databases (MEDLINE, PubMed, and EMBASE) were searched on December 22, 2024, for studies with patients undergoing ACLR with concomitant slope-reducing osteotomy. The authors adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Revised Assessment of Multiple Systematic Reviews guidelines and the Cochrane Handbook for Systematic Reviews of Interventions.

Six case series (Level IV) comprising 193 patients (27.5% female) with a mean age of 28.5 (range of means, 26.9-29.6) years were included. Four of 6 studies (66.7%) reported an indication for slope-reducing osteotomy, being a posterior tibial slope of 12° in revision or re-revision cases. Typical exclusion criteria for osteotomy reported by 5 studies included hyperextension of 5° to 10° or hypermobility (4 studies) and concomitant osteoarthritis (3 studies). Lysholm, Tegner, and visual analog scale scores all statistically increased postoperatively. Rates of return to sport at any level ranged from 81.3% to 100% and 25% to 100%, respectively. Graft failure rates in all studies ranged from 0% to 13%. Rates of recurvatum postoperatively ranged from 15% to 44%. Rates of hardware irritation/removal ranged from 0% to 46.2%.

The most common indication for slope-reducing osteotomies with concurrent ACLR is in the revision setting in patients with a posterior tibial slope above 12°. Slope-reducing osteotomies with ACLR improve patient-reported outcome measures postoperatively and have low rates of instability and retear rates. Complications with osteotomy include postoperative recurvatum, postoperative hyperextension, and hardware removal.

Level IV, systematic review of Level IV studies.

An excessive posterior tibial slope (PTS) is a risk factor for anterior cruciate ligament (ACL) rupture or rerupture, and it can be managed by an anterior closing wedge high tibial osteotomy (ACW-HTO). The effect of slope-changing osteotomies on patellar height is poorly described after infratuberosity ACW-HTO.

To assess the effect of ACW-HTO on patellar height using an infratuberosity approach.

Case series; Level of evidence, 4.

Patients who underwent ACW-HTO between January 2019 and March 2024 were assessed for eligibility. Among 98 cases, 94 knees were analyzed with a complete radiographic assessment for the patellar height evaluation. Patellar height was measured on lateral radiographs according to the Caton-Deschamps index (CDI), Insall-Salvati index (ISI), and Blackburne-Peel index (BPI). The change in patellar height was assessed postoperatively, as were the rates of cases with a postoperative difference <0.3, <0.5, or >0.5 points of the respective index. The change in patellar height category (baja, normal, or alta) after correction of the PTS was also evaluated.

In univariate analysis, no significant difference was found between pre- and postoperative radiographs for the patellar height indices (differences for ISI: +0.1 ± 0.1, P = .18; CDI: +0.1 ± 0.1, P = .41; BPI: +0.1 ± 0.2, P = .52). The patellar height variation was +0.5 points in only 1 case for CDI, and it was <0.5 points in all other cases (98.9%). Five cases (5.3%) exhibited a postoperative change in patellar height category when measured by the ISI (3 moved up a category, 2 moved down a category; P = .65). Eight cases (8.5%) changed category according to the CDI (6 moved up a category, 2 moved down a category; P = .14). Twelve cases (12.7%) changed category according to the BPI (7 moved up a category, 5 moved down a category; P = .55).

Infratuberosity ACW-HTO for tibial slope correction did not lead to significant changes in patellar height. However, slight variations in both directions were possible in a small portion of patients.

Rupture of the anterior cruciate ligament (ACL) is a common sports injury. Despite continuous improvements over the years, not all patients return to their preoperative activities after treatment of the ACL. Therefore, individualized treatment approaches based on transplant selection, reconstruction technique and biomechanical factors, such as the tibial slope and rotational instability are crucial. Autogenous transplants have different properties in terms of donor site morbidity, healing behavior and risk of rerupture. The individual needs of the patient should therefore be taken into consideration. In terms of the surgical technique, correct tunnel placement based on anatomical landmarks is essential. In addition, concomitant instabilities and meniscus injuries must be addressed. In the event of a rerupture, an exact analysis of the causes is necessary. Ultimately, the success of the treatment depends to a large extent on precise diagnostics and the treatment of both the ACL rupture and any injured accompanying structures.

Failure of anterior cruciate ligament (ACL) reconstruction may be associated with a number of technical, anatomic, and patient-related factors. In particular, increased posterior tibial slope is associated with a greater risk of failure after both primary and revision ACL reconstruction, likely a result of increased load across the ACL graft. Surgical treatment of increased posterior tibial slope most commonly involves an anterior closing-wedge osteotomy of the proximal tibia, which may be performed in a simultaneous or staged fashion with ACL reconstruction. The authors describe a technique for combined, single-stage, all-inside ACL reconstruction and anterior closing-wedge osteotomy using staple fixation. The proposed technique provides adequate fixation of the osteotomy while minimizing hardware interference with the ACL tunnel placement and maximizing proximal femoral bone stock.

Different techniques of slope-decreasing anterior closed-wedge proximal tibial osteotomy (ACW-PTO) have been described. To determine the peri- and post-operative complication rate and obtain data on bone healing in ACW-PTO with an infratuberositary approach.

A total of 170 consecutive ACW-PTO of two sports-orthopaedic centres were retrospectively evaluated (97 and 73, respectively). Routine follow-up was performed after 6 weeks and was available in 166 cases (97.7%). Medical charts and x-rays of these cases were reviewed with regard to technique-specific complications. Lateral x-rays (n = 155) at 6 weeks post-operatively were evaluated with regard to bone healing (completely healed, partially healed or with no or delayed signs of bone healing). A multivariate binary logistic regression was performed to detect factors that influence bone healing.

There was one case with haematoma and superficial wound-healing problems after 5 weeks with progression to a deep wound infection and revision surgery (plate exchange) at 11 weeks after the index surgery. One case with delayed bone healing was treated with plate exchange combined with revision anterior cruciate ligament reconstruction after 4 months. The further course of both cases was uneventful. No other complications were observed. Therefore, the overall complication rate was 1.2% (2 out of 166). Radiologic evaluation at 6 weeks showed complete healing in 104 cases (67.1%), partial healing in 50 cases (32.3%) and delayed healing only in the aforementioned case (0.6%), respectively. All cases of partial healing showed complete healing at 12 weeks. In regression analysis, a completely closed osteotomy (odds ratio [OR] = 3.5, p = 0.003) and compression of the osteotomy (OR = 2.5, p = 0.026) were significantly associated with complete bone healing at 6 weeks.

ACW-PTO using an infratuberositary approach is very safe with regard to complication rate and shows rapid bone healing. The osteotomy should be completely closed and compression should be applied for optimal bone healing.

Case series with pooled data of two centres.

Level 4.

To quantify the effect of increasing the posterior tibial slope (PTS) on knee kinematics and the resultant medial and lateral meniscal forces.

In this controlled laboratory study, a 6 degrees of freedom (DOF) robotic testing system was used to apply external loading conditions to seven fresh-frozen human cadaveric knees: (1) 200-N axial compressive load, (2) 5-N m internal tibial +10-N m valgus torque and (3) 5-N m external tibial + 10-N m varus torque. Knee kinematics and the resultant medial and lateral meniscal forces were acquired for two PTS states: (1) native PTS and (2) increased PTS. Resultant forces in the medial and lateral meniscus were calculated using the principle of superposition.

In response to 5-N m external tibial + 10-N m varus torque, significantly more internal tibial rotation was observed after increasing PTS at 60° (p = 0.0156) and 90° (p = 0.0156) flexion. Increasing PTS caused significantly more medial tibial translation from 30° to 90° flexion in response to 5-N m internal tibial + 10-N m valgus torque. In response to 5-N m external tibial + 10-N m varus torque, the resultant force in the medial meniscus at 60° flexion decreased significantly after increasing PTS (32.8%, p = 0.016). Resultant forces in the lateral meniscus decreased significantly after increasing PTS at 30° (34.5%; p = 0.016) and 90° (29.7%; p = 0.031) flexion in response to 5-N m internal tibial + 10-N m valgus torque.

Increasing PTS in a native knee with intact cruciate ligaments affected 6 DOF knee kinematics and decreased resultant forces in the medial and lateral meniscus by up to 35% in response to combined rotatory loads. Therefore, increasing PTS during high tibial osteotomy in a knee with intact cruciate ligaments does not increase the force carried by the entire meniscus at time zero.

N/A.

Graft failure after anterior cruciate ligament reconstruction is multifactorial, with increased tibia slope identified as one of the risk factors. Several slope-correcting osteotomies have been proposed to address this in revision surgery, with most of the procedures using a supratuberosity or transtuberosity approach. Although satisfactory results have been presented, severe complications involving the extensor mechanism can occur. In this Technical Note, an infratuberosity anterior closing-wedge high tibial osteotomy is demonstrated for slope correction in anterior cruciate ligament-deficient knees in the revision setting.

The incidence of anterior cruciate ligament (ACL) injuries in skeletally immature patients has drastically increased over the last decades. Morphology of the knee might play an important role. This literature review provides a systematic overview of knee morphological factors relevant to ACL injury in skeletally immature patients. The hypothesis of the present study is that multiple knee morphological parameters-such as a steep medial and lateral tibial slope (MTS and LTS) and a narrow intercondylar notch-can be identified as potentially relevant factors for ACL injury in this population.

Systematic review according to PRISMA guidelines. MEDLINE, Embase and Cochrane were searched in December 2023 for studies reporting on knee morphology and ACL injury in skeletally immatures. The following inclusion criteria were used: English/Dutch studies, full-text available, human studies and skeletally immature patients. Parameters with clinical homogeneity and presented in two or more studies as means with standard deviation were included in a meta-analysis using RevMan. Parameters that could not be included in the meta-analyses were presented in a descriptive manner.

After screening 1825 studies, a total of 18 studies were included, of which 16 studies had parameters included in the meta-analyses. These studies investigated 31 knee morphological factors for ACL injury in skeletally immatures. Meta-analyses identified a smaller notch width index (NWI) (0.25 vs. 0.26, mean difference: -0.02 95% confidence interval [CI]: -0.03 to -0.01, p ≤ 0.00001) steeper MTS and LTS (4.8° vs. 3.6° (mean difference: 0.55° 95% CI: 0.09-1.01, p = 0.02) and 4.3° vs 2.8° (mean difference: 2.04° 95% CI: 0.75-3.32, p = 0.0003), respectively) and higher LTS/MTS ratio as risk factors for ACL injury in skeletally immature patients.

A small NWI, steeper MTS and LTS and higher LTS/MTS ratios were identified as relevant knee morphological factors for ACL injuries in skeletally immature patients.

Level III.

Asymmetric anterior closing-wedge high tibial osteotomy (ACWHTO) allows correction of both excessive posterior tibial slope (PTS) and varus deformity. However, the complexity of this surgery requires a high degree of accuracy, which is less likely to be achieved with standard instrumentations. This study aimed to determine the accuracy of 3D patient-specific cutting guides (PSCGs) to provide the accurate planned correction in the frontal and sagittal planes.

Eight sawbones tibiae were identically printed from the same patient data. An ACWHTO with a PSCG was performed on each sawbone. Postoperative measurements of PTS, mechanical medial proximal tibial angle (mMPTA), hinge area and hinge-posterior cruciate ligament (hinge-PCL) distance were compared with the preoperative planned measurements. The precision was defined as the absolute difference (∆) between the target planned values and postoperative values.

The mean accuracy was 0.6° ± 0.74° for PTS, 0.8° ± 0.71° for mMPTA, 0.3 ± 0.2 cm2 for hinge area and 0.1 ± 0.06 mm for hinge-PCL distance.

In the setting of sawbones, the use of PSCGs was a reliable and accurate method of achieving simultaneous correction in the frontal and sagittal planes during asymmetric ACWHTO.

Level V, basic science biomechanical laboratory study.

A 13-year-old adolescent boy presented with chronic anterior cruciate ligament (ACL) insufficiency and prior medial meniscectomy. Radiographic evaluation revealed a posterior tibial slope (PTS) of 20°, putting him at high risk of reinjury following ACL reconstruction (ACLR). Guided growth using anteriorly placed eight plates was used for 9 months, which reduced his PTS to 6°. Two months following plate removal, the patient underwent ACLR with lateral extra-articular tenodesis.

This previously proposed but never reported approach suggests that guided growth is a viable option to correct excessive PTS before ACLR in skeletally immature patients.

The significance of the posterior tibial slope (PTS) has increasingly come into focus in anterior cruciate ligament (ACL) reconstruction being a risk factor for ACL graft failure. Nevertheless, inconsistent data on the critical value of the PTS exist. The purpose of this study was to define a cut-off value for the PTS in ACL surgery.

In a retrospective cohort study, 350 revision ACL reconstructions (ACL-RR) with a failed ACL hamstring graft and 350 primary ACL reconstructions (ACL-R) were matched according to age, gender, concomitant injuries and graft characteristics and compared to a healthy control group. Using the proximal anatomic axis, lateral knee radiographs were evaluated for the PTS, interrater reliability was defined, ROC curves, Fischer's exact test and Baptista-Pike method were applied to define specificity and the odds ratio for a critical PTS value.

Radiographic evaluation proved excellent interrater reliability (intraclass correlation coefficient 0.969). Evaluation of the PTS revealed 10.0 ± 2.2 (5-15) degrees in the ACL-RR group, 7.8 ± 1.8 (4.2-13) degrees in the ACL-R group and 6.6 ± 1.9 (3.6-12) degrees in the control group with significant differences between the groups (p < 0.001). A PTS value of 10.1 degrees proved a specificity of 98% for the prediction of an ACL graft failure and indicated an 11-fold risk for a retear of the ACL.

A PTS exceeding 10.1 degrees carries an 11-fold risk for ACL graft failure and, therefore, should be considered in ACL reconstruction. These findings might serve as a cut-off value for the indication of a slope-reducing high tibial osteotomy in ACL surgery.

Level III.

If an increased posterior tibial slope (PTS) and concomitant unicompartmental osteoarthritis are present, a simultaneous sagittal (slope) and coronal correcting high tibial osteotomy has been recommended. However, no study has investigated the accuracy of such combined high tibial slope correction osteotomies.

(1) To report the accuracy of navigated high tibial slope correction osteotomies using patient-specific instruments (PSI) and (2) to analyze the influence of an open wedge osteotomy (OWO) versus a closed wedge osteotomy (CWO) and the hinge axis angle (HAA) on the accuracy of the PTS correction.

Cohort study; Level of evidence, 3.

All PSI PTS-reducing osteotomies performed at 1 institution between 2019 and 2022 were reviewed. Three-dimensional (3D) accuracy was defined as the mean absolute 3D angular difference between the planned and achieved surgical correction (in degrees) in 3D models of computed tomography data. The influence of OWO versus CWO and the HAA on the reported accuracy was analyzed and a cutoff defined using receiver operating characteristic curve analysis.

Eighteen patients who underwent a slope-reducing CWO (n = 9) or OWO (n = 9) were included. The 3D accuracy for PTS was 2.3°± 1.1° (mean ± SD), with CWO being more accurate than OWO (1.4°± 0.9° vs 3.1°± 0.6°; P < .01). Accuracy strongly correlated with the HAA (r = 0.788; P < .01). An HAA >38.9° predicted a PTS error >2° (odds ratio, 1.12 [95% CI, 1.04-1.20; P = .004]; area under the curve, 0.95 [95% CI, 0.89-1.00; P < .001]) corresponding to a coronal/sagittal correction of 0.8:1.

Slope-reducing osteotomy can accurately be achieved using PSI. CWO demonstrated an increased accuracy when compared with OWO, which strongly depended on the HAA. With an aim of combined PTS and coronal correction, CWO should be considered the primary choice for accurate slope reduction with a coronal/sagittal correction cutoff of 0.8:1 (HAA, 38.9°).

To explore the indications, outcomes, and complications related to slope-reducing osteotomies in the setting of anterior cruciate ligament (ACL) tears or graft failure. A secondary aim was to create an algorithm on the basis of the current literature and authors' opinions.

This study was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Studies were included if they reported on outcomes related to slope-reducing osteotomies both for primary ACL tears and revision ACL graft tears. The studies were analyzed to determine the radiographic outcomes, patient-reported outcomes (PROs), physical examination findings, and complications. Statistical analysis could not be performed because of the heterogeneity between studies.

A total of 148 studies were screened for inclusion in this systematic review and after full-text review, a total of 16 studies were included in this systematic review. Fourteen of the studies reported on pre- versus postoperative posterior tibial slope (PTS) and all but one reported significant decrease in PTS. Seven studies reported on pre- versus postoperative PROs, and all studies reported significant improvements in postoperative scores. Anterior tibial translation was measured in 8 studies, and all reported a significant decrease in anterior tibial translation postoperatively. The most common complication was postoperative hyperextension and irritation from hardware. Irritation from hardware was only reported in studies that used plates to fixate the osteotomy.

In conclusion, slope-reducing proximal tibial osteotomies performed concurrently or as a second-stage surgery with an anterior cruciate ligament reconstruction (ACLR) resulted in improved PROs and decreased ACLR failure rates. Slope-reducing proximal tibial osteotomies are an important treatment consideration for those patients with an increased PTS, especially for patients with a failed ACLR and a PTS ≥12°, to reduce the risk of ACLR failure.

Level IV, systematic review of Level IV studies.

To relate bone shape with anterior cruciate ligament (ACL) graft maturation, as evaluated by quantitative magnetic resonance imaging.

We retrospectively evaluated patients aged 18 to 60 years who underwent ACL reconstruction with a hamstring autograft with doubled semitendinosus and gracilis at our institution between 2018 and 2020 with isolated ACL injuries. All patients had a minimum follow-up period of 2 years. To evaluate alignment, radiographs of the knee were taken preoperatively. Postoperative 3T magnetic resonance imaging and patient-reported outcome scores were acquired at 2 years after surgery. A combined T1ρ/T2 quantification sequence and a 3-dimensional multiecho ultrashort echo time (UTE) cone sequence were obtained in a sagittal-oblique plane for better assessment of the ACL graft. After acquiring images, a manual segmentation for the ACL graft was performed to assess T1ρ, T2, and UTE T2∗ relaxation times. Correlations between radiographic parameters or patient-reported outcome scores and T1ρ, T2, and UTE T2∗ values were tested with Pearson correlation coefficients. Significance was defined as P < .05.

Participants were 28 patients (12 men and 16 women) who had a mean (SD) age of 34.3 (8.5) years and body mass index of 24.4 (4.5). A significant correlation was found between the preoperative posterior tibial slope (PTS) and the T1ρ, T2, and UTE T2∗ relaxation times (r = 0.41, P = .033; r = 0.47, P = .014; and r = 0.41, P = .030), indicating inferior graft maturation in patients with a higher PTS. Furthermore, a negative correlation was identified between the preoperative medial proximal tibial angle and the T1ρ, T2, and UTE T2∗ relaxation times (r = -0.39, P = .039; r = -0.46, P = .018; and r = -0.43, P = .024), indicating inferior graft maturation in patients with greater varus knee alignment.

The study findings suggest that an increased PTS and a lower medial proximal tibial angle are associated with inferior graft maturation as per T1ρ, T2, and UTE T2∗ imaging at 2 years post-ACL reconstruction.

Level IV, retrospective case series.

Increased tibial slope has been shown to lead to higher rates of anterior cruciate ligament graft failure. A slope-decreasing osteotomy can reduce in situ anterior cruciate ligament force and may mitigate this risk. However, how this procedure may affect the length change behavior of the medial ligamentous structures is unknown.

The purpose of this study was to examine the effect of anterior slope-modifying osteotomies on the medial ligamentous structures. It was hypothesized that (1) decreasing the tibial slope would lead to shortening of the superficial medial collateral ligament (sMCL), (2) while the fibers of the posterior oblique ligament (POL) would be unaffected.

Descriptive laboratory study.

Eight fresh-frozen cadaveric knee specimens underwent anatomic dissection to precisely identify the medial ligamentous structures. The knees were mounted in a custom-made kinematics rig with the quadriceps muscle and iliotibial tract loaded. An anterior slope-modifying osteotomy was performed and fixed using an external fixator, which allowed modification of the wedge height between -15 and +10 mm in 5-mm increments. Threads were mounted between pins positioned at the anterior, middle, and posterior parts of the tibial and femoral attachments of the sMCL and POL. For different tibial slope modifications, length changes between the tibiofemoral pin combinations were recorded using a rotary encoder as the knee was flexed between 0° and 120°.

All sMCL fiber regions shortened with slope reduction (P < .001) and lengthened with slope increase (P < .001), with the anterior sMCL fibers more affected than the posterior sMCL fibers. A 15-mm anterior closing-wedge high tibial osteotomy (ACWHTO) resulted in a 6.9% ± 3.0% decrease in the length of the anterior sMCL fibers compared with a 3.6% ± 2.3% decrease for the posterior sMCL fibers. A 10-mm anterior opening-wedge high tibial osteotomy (AOWHTO) increased anterior sMCL fiber length by 5.9% ± 2.3% and posterior sMCL fiber length by 1.6% ± 1.0%. The POL fibers were not significantly affected by a slope-modifying osteotomy.

Tibial slope-modifying osteotomies changed the length change pattern of the sMCL such that an AOWHTO increased whereas an ACWHTO decreased the sMCL strain. This effect was most pronounced for the anterior fibers of the sMCL. The length change pattern of the POL remained unaffected by slope-modifying osteotomy.

Surgeons should be aware that anterior tibial slope-modifying osteotomies affect the biomechanics of the sMCL. After an extensive ACWHTO, patients may develop a medial or anteromedial instability, while an AOWHTO may overconstrain the medial compartment.

The literature agrees that an increased posterior tibial slope (PTS) increases the risk of anterior cruciate ligament (ACL) rupture in adults. However, there is no consensus on the average normal value and it varies with growth. We carried out a systematic review of the literature to answer 4 questions faced with an increase in PTS in children: METHOD: We conducted a systematic review of the literature in accordance with PRISMA criteria. The inclusion criteria were all studies analyzing the association between increased PTS and the occurrence of knee disease in patients, the majority of whom were under 18 years of age or had immature skeletons. For each study, we recorded the demographic characteristics of the patients, the type of measurements performed, the PTS values and the association between the PTS value and the occurrence of pathology.

A total of 294 studies were identified. After analysis, 11 studies were included (n = 1173 patients). Six studies examined the association between PTS and anterior cruciate ligament (ACL) rupture (n = 5) or recurrence of rupture (n = 1). Two studies investigated the association between tibial slope and proximal tibial fracture and 3 studies investigated the association between tibial slope and growth disease (Osgood Schlatter (OSD) or osteochondritis dissecans of the knee). Of the 5 ACL studies, all studies found a significant increase in PTS in patients with ACL rupture (range min 2.1 ° max 4.3 °) compared with healthy subjects. Concerning growth lesions, 3 studies found an increased PTS in patients with OSD or osteochondritis. The studies concerning fractures of the proximal end of the tibia also found an increase in PTS.

This review highlighted the potential link between an abnormally high PTS value and the occurrence of knee pathologies in children, in particular ACL rupture. Children with a high PTS and an ACL rupture will require longer-term follow-up and should be warned of the greater risk of re-rupture.

IV; systematic review.

Axial malalignment in the coronal plane has been identified as a significant risk factor for knee cartilage damage, leading to osteoarthritis progression. However, the impact of sagittal axial deviation on cartilage damage remains underexplored. Biomechanical studies have suggested that an increased tibial slope leads to altered pressure distribution in the articular cartilage, potentially contributing to cartilage damage. Despite these biomechanical insights, clinical evidence linking increased tibial slope to cartilage damage is lacking.

This retrospective study focuses on patients who underwent surgical cartilage transplantation between January 2016 and July 2023. A total of 108 patients were divided into two groups based on the presence or absence of other pathologies contributing to cartilage damage. Clinical data, including tibial slope measurements from lateral radiographs, were collected. A further subgroup-matched pair analysis was conducted comparing cases with patellar lesions and healthy knees. Statistical analysis compared tibial slope values between groups and assessed correlations between tibial slope and cartilage lesion grade.

Patients without other identifiable pathologies exhibited a significantly higher medial tibial slope compared to those with known causative factors for cartilage damage (p < 0.05). Cartilage damage, particularly in the patellar region, was more prevalent in patients with an increased tibial slope. Patients with patellar lesions had a significant increased slope than healthy controls (p < 0.05). However, there was no significant correlation between cartilage lesion grade and tibial slope.

The study identified increased medial tibial slope as a possible independent risk factor for cartilage damage in the knee, especially in the patellar region.

Level IV.

Posterior tibial slope (PTS) has been identified as a possible modifiable risk factor for anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) failure. However, the findings in the literature are inconsistent. This may be explained by several different reasons, including different measurement methods, differing definitions of ACLR failure, and possible inclusion of suboptimal films.

To compare PTS values obtained using plain radiographs (XR-PTS) in a young (≤21 years of age), skeletally mature patient population with those obtained using magnetic resonance imaging (MRI), as well as to quantify the number of suboptimal lateral knee radiographs obtained across an integrated health care system and determine the potential effect of including these radiographs on summary statistics of XR-PTS.

Case-control study; Level of evidence, 3.

Skeletally mature adolescent and young adult patients ≤21 years of age were identified from the ACLR registry of Kaiser Permanente. The cases of concern were patients requiring revision ACLR. The controls were patients who had an ACLR and did not require a revision procedure. The XR-PTS measurements were made on plain radiographs by a single blinded reviewer. These results were compared with measurements obtained using MRI. The quality of each plain radiograph was evaluated by measuring posterior/distal femoral condylar overlap and length of tibial diaphysis captured on the radiograph. Summary statistics with and without inclusion of measurements made on suboptimal radiographs were calculated.

Of the initial 634 patients with ACLR (317 case-control pairs), 561 (88.5%) had radiographs available and were included for the analysis comparing radiograph to MRI slope measurements. For the evaluation of slope between case and control pairs with radiograph information available, there were 257 case-control pairs; there were 124 pairs when those with suboptimal radiographs were excluded. There was no difference in MRI-measured lateral tibial posterior slope or medial tibial posterior slope for the 257 case-control pairs with XR-PTS information and for the 124 pairs with optimal radiographs. XR-PTS in the revision cohort was significantly steeper than in the control group when suboptimal radiographs were included in the analysis. There was no difference when patients with suboptimal radiographs were excluded. PTS measurements made on plain radiographs were larger than those made on MRI. There was a poor correlation between measurements made using these 2 modalities (r = 0.22 for radiograph and medial PTS).

This study did not find a significantly steeper XR-PTS in patients who had to undergo revision ACLR when suboptimal radiographs were not included in the analysis. The present study's results confirmed the findings from a previous study of the same patient population that used MRI. However, there was poor correlation between PTS measurements made using plain radiograph and MRI.

To compare different measurement techniques of the posterior tibial slope (PTS) on lateral radiographs with the actual in situ PTS and evaluate the effect of tibial malrotation and image section length.

Actual PTS was measured on eight fresh-frozen tibiae using a portable 6-axis measuring arm with an accuracy of ±0.01°. True lateral radiographs were taken in the neutral position and after applying 10/20/30° internal/external rotation (IR/ER) and 5/10/15° varus/valgus rotation. The PTS was measured radiographically using five different reference axes: anterior tibial cortex (ATC), anatomical tibial axis, proximal tibial anatomical axis (PTAA), posterior tibial cortex (PTC) and fibular shaft axis (FSA).

The ATC and PTAA methods showed the lowest deviation from the actual PTS, while the PTC method showed the highest difference of 5.5 ± 1.5° (medial) and 7.1 ± 1.8° (lateral) among all tested methods (p < .001). The PTAA technique showed a 1.9 ± 1.4° (medial) and 2.9 ± 1.8° (lateral) difference from the actual slope (n.s.). ER caused the PTS to increase 0.7 ± 2.0° (10° ER, n.s.) to 3.4 ± 2.1° (30° ER, p < .05), whereas IR caused the PTS to decrease 1.6 ± 1.3° (n.s) to 4.1 ± 1.7° (p < .05) when comparing to the PTAA method for the neutral position. Varus and valgus rotation showed the highest deviation from the neutral rotation at 15° valgus (3.1 ± 2.1°, n.s.).

Tibial slope measurements have a high degree of variability between different measurement methods, while the ATC and PTAA methods showed the least deviation from the actual PTS measured in this in vitro model. Malrotation resulted in a severe distortion of the PTS values, which may alter preoperative planning and intraoperative results. Therefore, radiographic PTS measurements may be contrasted with more objective, reproducible and reliable measuring methods.

There is no level of evidence as this study was an experimental laboratory study.

We aimed to compare tibial soft tissue and bony slopes in patients with failed and non-failed ACL reconstructions (ACLR). We hypothesized that patients with failed ACLR have increased slopes compared to non-failed ACLR, and unexplained failures have higher slopes than failures with clear technical errors and failed synthetic ligaments.

Between 2015 and 2022, 130 patients with failed ACLR were retrospectively identified; 79 knees with adequate MRI scans were analyzed. These were compared to 57 non-failed ACLRs. MRI measurements included lateral and medial tibial bony slope (LBS, MBS) and lateral and medial meniscal slope (LMS, MMS). Subgroup analysis assessed for failures with technical errors and failed synthetic ligaments.

In all patients, the LMS and MMS reduced the bony slope towards the horizontal without reaching statistical significance. Failed ACLR had significantly higher MBS (7.1° ± 2.9 vs. 4.6° ± 2.5, p < 0.001) and MMS (5.6° ± 3.5 vs. 3.4° ± 2.8, p < 0.001). The area under the curve for MBS was 0.721 (CI: 0.628-0.813). The Youden optimal threshold value of MBS ≥ 5.1° (sensitivity 80 %, specificity 56.1 %) yielded an odd's ratio for failure of 5.1 (CI:2.3-11.6; p < 0.001). Revisions with technical errors had slopes that were not significantly different to non-failed ACLR. Revisions with synthetic grafts had MBS (7.3° ± 3.2 vs. 4.6° ± 2.5; p = 0.007) and MMS (6° ± 3.8 vs. 3.4° ± 2.8; p = 0.021) that were significantly higher to non-failed ACLR.

Medial bony and meniscal slopes are higher in patients with unexplained failed ACLRs and revisions with synthetic grafts, but ACLR with technical errors failed with slopes similar to non-failed ACLRs. Increased medial slope values are a risk factor for surgical failure.

III.

Posterior tibial slope (PTS) plays a vital role in knee stability. PTS of more than 12° may be considered with increased strain on the native anterior cruciate ligament (ACL) fibers. To handle the instability caused by changes in PTS degree, Proximal Tibial Anterior Closing Wedge Osteotomy (PT-ACWO) is adopted by surgeons.

Between October 2015 and October 2019, our department conducted a retrospective analysis of patients who experienced anterior cruciate ligament reconstruction (ACLR) graft failures, with a particular focus on pathological PTS. The time from initial ACLR to revision ranged from 1 to 10 years, with a mean of 2.5 years. Radiological assessments of PTS were conducted, and outcomes were quantified using the International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner activity scale. The surgical technique and the use of 3D Patient-Specific Instrumentation (PSI) were outlined. Preoperative imaging included the use of Kirschner wires to establish tibial plateau reference points, and 3D-PSI was employed to guide the location and depth of the tibial osteotomy, which was performed obliquely. In a notable instance, a novel tibial tunnel was mapped out, and ortho-bridge system (OBS) fixation was utilized to ensure adequate space for the new tunnel.

In a cohort of seven patients with a mean follow-up of 28.1 months, a significant reduction in PTS was noted postoperatively (median [interquartile range, IQR], from 15.27° [13.46°, 16.60°] to 6.25° [5.89°, 6.78°]; P = 0.002). IKDC score improved to 85.10 (80.25, 88.10), P < 0.001; the Lysholm score to 88.00 (73.00, 90.50), P < 0.001; and the Tegner score to 8.00 (7.20, 8.05), P = 0.025 at final follow-up. Skin incision healing delays occurred in two instances, yet achieved closure by six weeks. Radiographs at three months demonstrated faster bone healing in oblique osteotomies than transverse ones. Knee joint stability was maintained, with no additional complications or evidence of instability noted. Magnetic resonance imaging (MRI) confirmed graft integrity in all patients, without signs of enlargement or mispositioning at last observation.

An augmented PTS angle exceeding 12 may constitute a potential etiology for the failure of ACLR grafts. In such patients, the implementation of ACLR combined with PT-ACWO could mitigate the risk of surgical failure during initial ACLR or subsequent revision procedures.

Younger age and steep posterior tibial slope (PTS) have been reported as risk factors for graft failure after anterior cruciate ligament reconstruction (ACLR). Few studies have evaluated these risk factors simultaneously in a large cohort of patients undergoing double-bundle ACLR (DB-ACLR). Therefore, this retrospective study aimed to simultaneously investigate known risk factors such as PTS and age in DB-ACLR, determine their thresholds and calculate odds ratios (ORs).

We investigated 482 knees that underwent DB-ACLR with a follow-up period of at least 2 years. Receiver operating characteristic analysis determined cut-off values for age and PTS for graft failure. Subsequently, logistic regression analysis was conducted to evaluate the effects of age, sex, height, weight, laterality, surgical waiting period, pre-operative sport type and level, meniscal injury, hyperextension, general joint laxity and PTS on graft failure.

Graft failure was observed in 33 out of 482 knees (6.8%). Notably, the graft failure group was significantly younger (18.0 ± 5.0 years [standard deviation] vs. 30.4 ± 13.1 years, p < 0.01) and had a steeper PTS (11.9 ± 2.3° [standard deviation] vs. 9.6 ± 2.9°, p < 0.01) than the group with no graft failure. The cut-off values were 20.0 years for age (specificity, 64.6%; sensitivity, 87.9% and area under the curve, 0.808) and 12.0° for PTS (specificity, 70.9%; sensitivity, 69.7% and area under the curve, 0.734). Logistic regression analysis identified an age of <20 years (OR = 10.1; p < 0.01), PTS of ≥12° (OR = 5.6; p < 0.01) and pre-operative participation in pivoting sports (OR = 6.0; p < 0.01) as significant risk factors for graft failure.

We identified an age of <20 years, PTS of ≥12° and pre-operative participation in pivoting sports as significant risk factors for graft failure after DB-ACLR.

Level III.

➤ Posterior tibial slope (PTS) of ≥12° represents an important risk factor for both anterior cruciate ligament (ACL) injury and ACL reconstruction failure.➤ PTS measurements can significantly differ on the basis of the imaging modality and the measurement technique used. PTS should be measured on strictly lateral radiographs, with a recommended proximal tibial length of 15 cm in the image. The PTS measurement can be made by placing 2 circles to define the proximal tibial axis, 1 just below the tibial tubercle and another 10 cm below it. PTS measurements are underestimated when made on magnetic resonance imaging and computed tomography.➤ Slope-reducing osteotomies can be performed using a (1) supratuberosity, (2) tubercle-reflecting transtuberosity, or (3) infratuberosity method. The correction target remains a topic of debate. Although it is controversial, some authors recommend overcorrecting the tibial slope slightly to a range of 4° to 6°. For instance, if the initial slope is 12°, a correction of 6° to 8° should be performed, given the target tibial slope of 4° to 6°.➤ Clinical outcomes following slope-reducing osteotomies have been favorable. However, potential complications, limited data with regard to the impact of slope-reducing osteotomies on osteoarthritis, and uncertainty with regard to the effects on the patellofemoral joint are notable concerns.➤ Patients with complex deformities may need biplanar osteotomies to comprehensively address the condition.

Background: Excessive posterior tibial slope (PTS) has been associated with a higher risk of graft failure after anterior cruciate ligament reconstruction (ACLR). Although anterior closing wedge osteotomy (ACWO) can reduce the PTS, it may also change the coronal alignment and patellar height. Purpose: To elucidate the radiological outcomes after infratubercle ACWO, specifically to evaluate its influence on perioperative changes in patellar height. Methods: Patients who underwent infratubercle ACWO with combined ACLR with a minimum follow-up of 3 months were included. Surgery was indicated when the PTS was greater than 12°. Radiological evaluation included measurements of the hip-knee-ankle angle (HKA), PTS, femoral patellar height index (FPHI), and Caton-Deschamps index (CDI) preoperatively and 3 months postoperatively. Patellar height was classified as patella baja, normal, or alta based on CDI values. Knee recurvatum was measured preoperatively and at final follow-up. Results: A total of 21 patients with a mean age of 21.6 ± 3.0 years were included. Although HKA did not significantly change, significant corrections were achieved in the PTS from 14.5° ± 1.6° to 5.7° ± 1.0° (p < 0.001). No significant change in FPHI was found (preoperative: 1.33 ± 0.11 vs postoperative: 1.30 ± 0.09). Patellar height categories showed no significant differences pre- and postoperatively, while three patients (14.3%) changed their patellar height category (all moved up one category). Knee recurvatum increased significantly from 4.9° ± 2.9° preoperatively to 7.8° ± 3.1° at the final follow-up (p < 0.001). Conclusions: Precise sagittal correction was achieved after infratubercle ACWO without altering the coronal alignment and patella height. Level of Evidence: IV, Case series.

Knee osteotomies are essential orthopedic procedures with the ability to preserve the joint and correct ligament instabilities. Literature supports the correlation between lower limb malalignment and outcomes after knee ligament reconstruction and cartilage procedures. Concepts such as joint line obliquity, posterior tibial slope angle, and intra-articular deformity correction are integral components of both preoperative planning and postoperative evaluations. The concept of preserving and/or restoring joint line congruence during simultaneous correction of varus or valgus deformity can be achieved through several different approaches. With advancements in osteotomy research and surgical planning technology, the surgical decision-making has increased in complexity. Based upon a patient's specific deformity, decisions need to be made whether to perform a single-level (proximal tibia or distal femur) versus double-level (both proximal tibia and distal femur) osteotomy, and whether to correct deformity in a single plane (coronal or sagittal) or perform a biplanar osteotomy, correcting two of the malalignments in either coronal, sagittal, or axial planes. Osteotomy procedures prioritize safety, reproducibility, precision, and meticulous planning. Equally important is the proactive management of possible complications and the implementation of preventive strategies for complications such as hinge fractures and unintentional changes to alignment in other planes. This review navigates the intricate landscape of lower limb alignment, commencing with foundational definitions and rationale for performing osteotomies, progressing through the planning phase, and addressing the critical aspect of complication prevention, all while looking ahead to anticipate future advancements in this field. However, rotational osteotomies and tibial tubercle osteotomies in isolation or as an adjunct procedure are beyond the scope of this review.

Recent advances in surgical techniques and planning for knee-based osteotomies have led to improvements in addressing lower extremity malalignment. Part 1 of this review presented the biomechanical and clinical rationale of osteotomies, emphasizing the importance of osteotomies for restoring normal knee kinematics. In Part 2 of this review, indications, surgical technique and outcomes of osteotomies to correct coronal, sagittal and axial plane deformities will be examined. Traditional high tibial and distal femoral osteotomies will be discussed in addition to more recent advanced techniques including biplanar corrections and double-level osteotomies, as well as slope-correcting osteotomies. Patient-specific instrumentation and its use in more complex corrections will also be addressed.

Patients with excessive posterior tibial slope (PTS) may have higher risks of anterior cruciate ligament (ACL) reconstruction (ACL-R) failure, and clinical outcomes after revision of ACL-R procedures are typically poor.

This study aimed to perform a systematic review of the literature summarizing the clinical and radiological outcomes of the surgical treatment of ACL insufficiency in the setting of excessive PTS using a tibial deflexion osteotomy combined with ACL-R.

A systematic review of the literature was performed using PubMed, Cochrane Library, and OVID Medline databases from 1990 to present. Inclusion criteria were studies of outcomes of isolated tibial deflexion osteotomies performed with primary or revision ACL-R in the English language. Data extracted included study demographic information, type of tibial deflexion osteotomy and concomitant procedures, radiological outcomes, patient-reported outcome scores, and postoperative complications.

Six studies, with 133 knees were identified. All included studies were retrospective case series, with a weighted mean follow-up of 3.39 years. In 106 of 133 (79.7%) knees, tibial deflexion osteotomy was performed concomitantly with an ACL-R, whereas in 27 of 133 (20.3%) knees, the procedures were staged. 22, 45, and 66 of 133 knees (16.5%, 33.8%, and 49.6%) underwent primary, first revision, and second or greater revision ACL-R, respectively. Three of 133 (2.25%) knees demonstrated recurrent ACL graft failure at the final follow-up. On average, PTS decreased from 15.2° preoperatively to 7.1° postoperatively. The mean International Knee Documentation Committee, Lysholm, and Tegner scores increased from 42.5, 46.4, and 4.2 preoperatively to 71.8, 89.0, and 6.7 postoperatively.

The results of this review suggest that combined ACL-R and tibial deflexion osteotomy may be effective in decreasing PTS and improving knee function and stability.

Systematic Review; Level of evidence 4.

To systematically review the literature evaluating patient-reported outcomes and return to sport after re-revision anterior cruciate ligament reconstruction (ACLR) procedures. The secondary objectives were 2-fold: to identify the risk factors that lead to revision ACLR failure and to assess the secondary knee structure injuries after the initial revision ACLR.

A systematic review of the literature was performed using the MEDLINE/PubMed and Cochrane databases. The inclusion criteria were outcomes of re-revision ACLR, minimum of 2 years' follow-up, human studies, and English language. Basic science articles, epidemiologic studies, editorials, surgical technique articles, surveys, cadaveric studies, and animal studies were excluded.

Fifteen studies met the inclusion criteria and were considered for review. There were 6 Level III and 9 Level IV studies that included 399 patients undergoing re-revision ACLR. The rate of concomitant meniscal lesions at the time of re-revision ranged from 35% to 90%. The prevalence of concomitant cartilaginous lesions at the time of re-revision ranged from 13.6% to 90%. Compared with preoperative scores, patient-reported outcomes overall improved after re-revision ACLR, with mean preoperative Lysholm scores ranging from 38.4 to 73.15 that improved to postoperative scores ranging from 68 to 87.8. However, return to sport at preinjury levels was inconsistent, with rates ranging from 12.5% to 80%.

Re-revision ACLR was found to restore knee stability and improve functional outcomes. Despite this improvement, there was a low rate of return to sport at the preinjury level. Functional outcomes were also inferior when compared with primary ACLR. In addition, concomitant knee pathologies were found to rise in prevalence compared with revision and primary ACLR cases.

Level IV, systematic review of Level III and IV studies.

Failure of anterior cruciate ligament reconstruction (ACLR) is a common yet devastating complication due to inferior clinical outcomes associated with revision ACLR. Identifying the cause and associated risk factors for failure is the most important consideration during preoperative planning. Special attention to tunnel quality, concomitant injuries, and modifiable risk factors will help determine the optimal approach and staging for revision ACLR. Additional procedures including lateral extra-articular tenodesis and osteotomy may be considered for at-risk populations. The purpose of this review is to explore causes of ACLR failure, clinical indications and appropriate patient evaluation, and technical considerations when performing revision ACLR.

Because of the increased prevalence of revision anterior cruciate ligament (ACL) reconstruction, there has been a desire to understand the role of posterior tibial slope on increased anterior tibial translation and increased ACL graft forces. One potential concern in supratubercle anterior closing wedge proximal tibial osteotomy (ACW-PTO) for decreasing the posterior tibial slope is the risk of altering the patellar height.

To radiographically assess changes in (1) patellar height, (2) anterior tibial translation, and (3) posterior tibial slope after supratubercle ACW-PTO.

Case series; Level of evidence, 4.

Patients who underwent supratubercle ACW-PTO by a single surgeon between July 2019 and June 2023 were included. Standardized lateral knee weightbearing radiographs to assess patellar height (via the Caton-Deschamps index), anterior tibial translation of the lateral tibial plateau relative to the lateral femoral condyle, and posterior tibial slope were obtained at 4 time points (preoperatively and 1 day, 3 months, and 6 months postoperatively). Paired t test was used to compare differences between preoperative, 1-day, and 3- and 6-month values for patellar height as measured using the Caton-Deschamps index and for posterior tibial slope. Paired t test was also used to compare differences in the preoperative and 6-month postoperative values for anterior tibial translation.

In 20 patients after ACW-PTO, the Caton-Deschamps index demonstrated a significant increase in patellar height on postoperative day 1 (P < .001) but no significant differences at 3 (P = .057) and 6 (P = .176) months postoperatively. Anterior tibial translation on standing lateral knee radiographs was significantly decreased by a mean of 8.9 mm from preoperatively to 6 months postoperatively (P < .001). Posterior tibial slope was significantly decreased by a mean of 11.2° from preoperatively to 6 months postoperatively (P < .001).

Supratubercle ACW-PTO performed for ACL reconstruction failure in the setting of an increased posterior tibial slope did not induce significant changes in patellar height postoperatively. Furthermore, after ACW-PTO, there was a significant decrease in anterior tibial translation and posterior tibial slope.

Increased posterior tibial slope (PTS) has been identified as a risk factor for failure after anterior cruciate ligament (ACL) reconstruction. Correction of PTS may improve outcomes after revision ACL reconstruction. There are conflicting reports demonstrating the measurement of the PTS on standard short knee (SSK) radiographs versus full-length lateral (FLL) radiographs including the entire tibia.

To compare PTS measurements between SSK and FLL radiographs in patients who failed primary ACL reconstruction. It was hypothesized that there would be high variability between the SSK and FLL radiographic measurements.

Cohort study (diagnosis); Level of evidence, 2.

The medial and lateral PTS were measured on the SSK and FLL radiographs of 33 patients with failed primary ACL reconstructions. All measurements were performed by 2 trained independent observers (A.A.M., J.S.), and inter- and intraobserver reliability were calculated using the intraclass correlation coefficient (ICC). Measurements recorded by the observer with the higher intraobserver ICC were used for comparison of the PTS on SSK versus FLL radiographs.

Both the inter- and the intraobserver reliability values of the PTS measurements were excellent. There was a significant difference in mean PTS on the medial plateau as measured on the SSK and FLL radiographs (11.2°± 5.3° vs 12.5°± 4.6°; P = .03), with the FLL radiographs demonstrating higher PTS. There was also a significant difference in the mean PTS on the lateral plateau as measured on SSK versus FLL radiographs (10.7°± 4.3° vs 12.2°± 4°, respectively; P = .01), with the FLL radiographs demonstrating higher PTS. Notably, 66.67% of the absolute measurements for PTS on the medial plateau differed by ≥2°, with variability as high as 8.5°.

Results indicated that FLL and SSK radiographs are not interchangeable measurements for PTS associated with failed ACL reconstruction. Because FLL radiographs demonstrate less variability than SSK radiographs, we recommend obtaining them to evaluate these complex patients.

Posterior tibial slope (PTS) is an important anatomic parameter of the knee related to anteroposterior instability. Biplanar stereoradiography allows for simultaneous low-dose acquisition of anteroposterior and lateral views with 3D capability, enabling separate lateral and medial plateau analyses. We aimed to evaluate the possibility and compare the reproducibility of measuring medial and lateral PTS on EOS® images with two different patient positionings and compare it with CT of the knees as the gold standard.

This is a retrospective study including volunteers who underwent lower limb stereoradiography and knee CT from 01/08/2016 to 07/31/2019. Sixty legs from 30 patients were studied. PTS were measured using stereoradiography and CT by two radiologists. Intraclass correlation was used to calculate intrarater and interrater reproducibilities. Pearson's correlation coefficients were used to calculate the correlation between stereoradiography and CT. We also compared the reproducibility of the stereoradiography of volunteers with 2 different positionings.

The mean stereoradiography PTS values for right and left knees were as follows: lateral, 12.2° (SD: 4.1) and 10.1° (SD: 3.5); medial,12.2° (SD: 4.4) and 11.6° (SD: 3.9). CT PTS mean values for right and left knee are as follows: lateral, 10.3° (SD:2.5) and 10.6° (SD: 2.8); medial: 8.7° (SD: 3.7) and 10.4° (SD: 3.5). Agreement between CT and EOS for angles between lateral and medial PTS was good (right, 0.874; left, 0.871). Regarding patient positioning on stereoradiography, interrater and intrarater reproducibilities were greater for patients with nonparallel feet (0.738-0.883 and 0.870-0.975).

Stereoradiography allows for appropriate delineation of tibial plateaus, especially in patients with nonparallel feet, for the purpose of measuring PTS. The main advantage is lower radiation doses compared to radiography and CT.

To simulate the effect of supratuberosity tibial anterior closing-wedge osteotomy (ACWO) in knees with posterior tibial slope (PTS) ≥12° on patellar height when aiming for a target PTS of 5°.

The authors retrospectively reviewed true lateral radiographs of the knees of skeletally mature patients scheduled for primary anterior cruciate ligament reconstruction and included all knees with excessive PTS (≥12°). Coordinates of 11 landmarks were digitized to calculate patellar height (Caton-Deschamps index, CDI) and mid-shaft posterior tibial slope (mPTS). The change in patellar height following a simulated supratuberosity ACWO was calculated and compared for knees with patella norma versus alta. A linear univariable regression model predicted the effect of change in mPTS on CDI.

In the final cohort of 83 patients, a simulated supratuberosity ACWO increased CDI from 1.13 (range, 0.73-1.74) to 1.29 (range, 0.84-1.91; P < .001). In 56 patients with patella norma, a simulated supratuberosity ACWO increased CDI from 1.02 (range, 0.73-1.19) to 1.18 (range, 0.84-1.41; P < .001), whereas in patients with patella alta, a simulated supratuberosity ACWO increased CDI from 1.33 (range, 1.20-1.74) to 1.52 (range, 1.36-1.91; P < .001). The linear regression model revealed that a 1° decrease in mPTS increased CDI by 0.02.

Simulation of a supratuberosity ACWO revealed that the procedure increases patellar height in all knees but did not induce significant differences in patellar height characteristics between knees with patella norma versus alta. A linear regression model revealed that a 1° decrease in mPTS could theoretically increase CDI by 0.02.

If preoperative planning indicates that supratuberosity ACWO would increase patellar height from norma (CDI <1.2) to alta (CDI ≥1.2), the surgeon could consider a trans- or infra-tuberosity ACWO, which is less likely to increase patellar height.

It has become increasingly recognized that a steep posterior tibial slope is a modifiable risk factor for the failure of an anterior cruciate ligament reconstruction. An anterior closing wedge osteotomy (ACWO) may be performed to flatten the slope, and this osteotomy may be performed above, through, or below the tibial tuberosity. A supra-tuberosity technique may increase the patellar height. However, this increase may be modest, may not affect the clinical outcomes, and is only one risk that I would consider when deciding whether to perform an ACWO above, through, or below the tibial tuberosity. The short proximal fragment of supra-tuberosity ACWO mandates a short anterior cruciate ligament reconstruction tibial tunnel and may compromise fixation of the osteotomy. A trans-tuberosity ACWO usually requires a tibial tuberosity osteotomy, which requires slower postoperative mobilization and risks nonunion or fracture of the tibial tubercle. And, an infra-tuberosity ACWO has lesser healing potential than a more proximal osteotomy.

Postoperative laxity correlates with negative clinical outcomes after anterior cruciate ligament reconstruction (ACLR). The influence of lateral extra-articular tenodesis (LET) on anteroposterior translation is unclear.

This study aimed to evaluate the reduction in radiographic static anterior tibial translation (SATT) and dynamic anterior tibial translation (DATT) after LET as an adjunctive procedure to ACLR. It was hypothesized that adding a LET procedure would have no effect on postoperative SATT and DATT.

Cohort study; Level of evidence, 3.

Patients who underwent primary ACLR with hamstring tendon autografts between 2020 and 2022 were reviewed, and those who underwent ACLR and LET as an anterolateral associate procedure were paired 1 to 1 with those who underwent isolated ACLR (control) based on age, sex, preoperative SATT, and posterior tibial slope (PTS). The indications for LET were age <18 years and anterolateral rotary instability (grade ≥2 pivot shift). A previously validated technique was used to measure SATT, DATT, and PTS on lateral weightbearing and lateral stress knee radiographs. Preoperative and 9-month postoperative radiographs were compared between the 2 groups.

A total of 72 patients were included in the analysis (n = 36 patients in each group). The inter- and intraobserver reliability of the SATT, DATT, and PTS measurements was excellent (intraclass correlation coefficients, 0.88-0.99). The mean pre- and postoperative SATT in the ACLR+LET group was 2.44 ± 2.90 mm and 2.44 ± 2.38 mm, respectively, compared with 2.60 ± 2.99 mm and 2.12 ± 2.74 mm, respectively, in the control group. The mean pre- and postoperative reduction in side-to-side DATT in the ACLR+LET group was 5.44 ± 4.65 mm and 1.13 ± 2.95 mm, respectively, compared with 5.03 ± 3.66 mm and 2 ± 3.12 mm, respectively, in the control group. There was no pre- to postoperative difference in SATT (P = .51). However, the side-to-side DATT was reduced by 3.66 ± 3.37 mm postoperatively (P < .001), without significant differences between groups (P = .24).

Including a LET procedure for patients undergoing ACLR did not reduce SATT; that is, it did not decrease the amount of tibial translation due to physiological axial load.

Anterior cruciate ligament (ACL) reconstruction (ACLR) is used to treat clinical instability post ACL rupture, however, there is a high rate of incomplete return to sport and rerupture. There is increasing interest in posterior tibial slope as an intrinsic risk factor for ACLR failure and persistent instability. Zoobiquity describes the collaboration between the human and veterinary professions in order to advance the scientific understanding of both fields. Given the cranial cruciate ligament (CCL) in dogs is synonymous with the anterior cruciate ligament in humans, functioning to control internal rotation and anterior translation, but osteotomies, rather than ligament reconstruction, are the mainstay of treatment for CCL rupture, this editorial sort to gain insights into this form of treatment from the veterinary world. Level of Evidence: Level V, evidence.