Total knee arthroplasty (TKA) is the gold-standard treatment for end-stage osteoarthritis (OA), offering substantial pain relief and functional improvement. With the rising incidence of sports-related injuries and advancements in anterior cruciate ligament reconstruction (ACLR) techniques, an increasing number of patients undergoing TKA have a history of ACLR. However, the impact of prior ACLR on postoperative complications and functional recovery after TKA remains controversial.

This study performed a systematic search across four databases, including case-control and cohort studies reporting on the outcomes of TKA following ACLR. Primary endpoints included infection, reoperation, prosthesis revision, thrombosis, and postoperative stiffness following manual release under general anaesthesia, with results compared to those of a control group of patients receiving TKA for primary OA. Secondary endpoints were operative time and postoperative range of motion in both flexion and extension. This study was registered in PROSPERO under the registration number CRD420250635375.

A total of nine studies were included in this study, involving 4381 participants, with 1112 undergoing TKA with ACLR history and 3269 undergoing TKA for primary OA. This study showed that the operative time of TKA after ACLR was significantly extended (P < 0.01), but there was no significant difference in postoperative infection, reoperation, prosthesis re-revision, thrombus, postoperative stiffness following manual release under general anaesthesia, and range of motion in both flexion and extension.

Although the operation time of TKA after ACLR was extended, the complication rate and postoperative functional recovery of TKA were not significantly different from those of primary OA patients. This study provided an evidence-based basis for preoperative assessment and patient management.

To evaluate whether tibiofemoral rotation is associated with a concurrent anterolateral ligament (ALL) injury and pivot-shift grading in patients with a primary anterior cruciate ligament (ACL) tear.

In this multicenter cross-sectional study constituting a secondary analysis of previous studies, medical records and magnetic resonance imaging (MRI) scans of patients with unilateral primary ACL injury were reviewed. Demographics and pivot-shift grading were collected. ALL was identified on MRI coronal images and categorized as intact or injured. Tibiofemoral rotation angle (TFA) was measured on axial MRI. Optimal TFA cut-off associated with ALL injury was identified by a receiver operating characteristic (ROC) curve.

Of 206 included patients, 152 (73.8%) exhibited signs of ALL injury. Pivot-shift tests were predominantly graded as 2 (71.4%), and notably, all Grade 3 pivot-shift assessments were associated with ALL injury. Mean TFA was significantly higher in cases with ALL injury (5.2 ± 3.6°) compared to intact ALL cases (2.7 ± 3.5°; p < 0.001). A positive correlation was observed between pivot-shift grading and TFA (r = 0.204, p = 0.003). Optimal TFA cut-off value, based on the absolute measurement, for predicting ALL injury was 2.5° (sensitivity: 0.77; specificity: 0.55). Patients with TFA ≥ 2.5° had a significantly higher risk of ALL injury (odds ratio: 3.34, 95% confidence interval [CI]: 1.74-6.42, p < 0.001); when combined with pivot-shift Grade 2 or 3, this risk substantially increased to 13.68 (95% CI: 6.29-29.84, p < 0.001).

Higher TFA was associated with an increased prevalence of ALL injuries and a high-grade pivot-shift in ACL-deficient patients. Patients with a TFA ≥ 2.5° showed a threefold higher likelihood of ALL injuries, and this risk further escalated with a higher-grade pivot-shift.

Level 3 cross-sectional study.

Additional anterolateral ligament (ALL) reconstruction has been associated with improved clinical outcomes and reduced failure rates in anterior cruciate ligament (ACL) reconstruction. Despite the excellent clinical results reported, there is still a heated debate about its indications. Currently, the indications are mainly based on the patient's clinical criteria and not the imaging diagnosis of the injury of this ligament.

To compare the clinical outcomes of patients undergoing isolated ACL reconstruction and combined ACL and ALL reconstruction conditioned to intraoperative ultrasound-guided diagnosis of the ALL lesion.

Cohort study; Level of evidence, 3.

A retrospective analysis of prospectively collected data was performed. Patients undergoing primary ACL reconstruction between January 2017 and January 2022 were included. Patients were excluded if they had a previous history of ipsilateral knee surgery or if they underwent other concomitant procedures, including multiligament reconstruction surgery or osteotomy. The decision to perform an ALL reconstruction in addition to isolated ACL reconstruction was based on ultrasound diagnosis of this lesion. At the end of the study period, further knee injury and any other reoperations or complications were recorded and compared between patients who had isolated ACL reconstruction (no-ALLR group) and combined ACL and ALL. Propensity score matching was performed between groups. A multivariable analysis using the penalized Cox model was performed to explore the relationship between the graft rupture, surgical procedure type, and potential explanatory variables.

A total of 339 patients met the predefined eligibility criteria; 146 ACL reconstructions were performed in an isolated manner (no-ALLR group) and 193 were combined with ALL (ALLR group). After matching, 130 patients were allocated to each group. The mean follow-up was 36.7 months. The overall graft failure rate was 4.6% (6.9% in the no-ALLR group and 2.3% in the ALLR group; P = .076). The adjusted Cox regression showed that graft failure rate was nonsignificantly different between the groups (adjusted hazard ratio [HR], 0.36 [95% CI, 0.096-1.364]; P = .133). Younger age (≤20 years) was associated with graft failure (adjusted HR, 0.29 [95% CI, 0.121-0.719]; P = .007).

Combined ACL and ALL reconstruction conditioned to intraoperative ultrasound-guided diagnosis of the ALL lesion has an equivalent ACL graft failure rate to isolated ACL. Intraoperative ultrasound diagnosis of an ALL injury may be an indication for the addition of an ALL reconstruction.

Anterior cruciate ligament (ACL) tears are prevalent knee injures, particularly among active individuals. Accurate and timely diagnosis is essential for determining the optimal treatment strategy and assessing patient prognosis. Various previous studies have demonstrated the successful application of deep learning techniques in the field of medical image analysis. This study aimed to develop a deep learning model for detecting ACL tears in knee magnetic resonance Imaging (MRI) to enhance diagnostic accuracy and efficiency. The proposed model consists of three main modules: a Dual-Scale Data Augmentation module (DDA) to enrich the training data on both the spatial and layer scales; a selective group attention module (SG) to capture relationships across the layer, channel, and space scales; and a fusion module to explore the inter-relationships among various perspectives to achieve the final classification. To ensure a fair comparison, the study utilized a public dataset from MRNet, comprising knee MRI scans from 1250 exams, with a focus on three distinct views: axial, coronal, and sagittal. The experimental results demonstrate the superior performance of the proposed model, termed SGNET, in ACL tear detection compared with other comparison models, achieving an accuracy of 0.9250, a sensitivity of 0.9259, a specificity of 0.9242, and an AUC of 0.9747.

The potential influence of a preoperative anterolateral ligament (ALL) lesion seen on magnetic resonance imaging (MRI) on the mid- and long-term surgical outcomes of anterior cruciate ligament (ACL) reconstruction is still controversial.

To evaluate the clinical outcomes and failure rate of isolated ACL reconstruction at a minimum 5-year follow-up in patients with and without ALL injury diagnosed preoperatively using MRI.

Cohort study; Level of evidence, 2.

A prospective cohort of patients with acute ACL injury was divided into 2 groups based on the presence (ALL injury group) or absence (control group) of ALL injury on preoperative MRI. This is a longer-term follow-up study of a previously published study that had a minimum 2-year follow-up. Both groups underwent anatomic isolated reconstruction of the ACL. The Lysholm and subjective International Knee Documentation Committee scores, KT-1000 arthrometer and pivot-shift tests, reconstruction failure rate, incidence of contralateral ACL injury, presence of associated meniscal injury, and presence of knee hyperextension were evaluated. The evaluation at the 5-year follow-up was also compared with the same patient's evaluation at 2 years of follow-up.

A total of 156 patients were evaluated. No significant differences were found between the groups in the preoperative evaluation. In the postoperative evaluation, patients in the ALL injury group had a higher reconstruction failure rate (14.3% vs 4.6% for the control group; P = .049) and worse clinical outcomes according to the Lysholm scores (85.0 ± 10.3 vs 92.3 ± 6.6; P < .00001). Although the pivot-shift test results were similar, anteroposterior translation using the KT-1000 arthrometer revealed worse results for the ALL injury group (2.8 ± 1.4 mm vs 1.9 ± 1.3 mm; P = .00018). Patients in the ALL injury group also had an increase in KT-1000 arthrometer values from 2 to 5 years (2.4 ± 1.6 vs 2.8 ± 1.4; P = .038). Patients in the control group had no differences in outcomes from 2 to 5 years of follow-up.

Combined ACL and ALL injuries were associated with significantly less favorable outcomes than were isolated ACL injuries at a minimum follow-up of 5 years after isolated ACL reconstruction with hamstring autograft. Patients with concomitant ALL injury showed a higher failure rate and worse functional scores. Also, knee stability tended to slightly worsen from 2 to 5 years in cases of associated ALL injury.

The purpose of this study was to evaluate the impact of squats after the anterior cruciate ligament (ACL) reconstruction on the ACL graft, considering new data on biomechanics, posterior tibial slope (PTS) and anterolateral ligament (ALL).

Utilising finite element analysis on the new 14-component knee joint model, we have evaluated stresses on the knee elements separately for the knee with a native double-bundle ACL and with a single-bundle ACL graft for the 5° and 14° PTS variants during both conventional and Smith machine horizontal squats.

Replacing a native ACL with a single-bundle graft causes an overstrain on the graft compared to the intact ACL under all conditions. Stresses on the ACL, ACL graft and ALL are much higher during the Smith machine squats compared to the conventional ones. The stress on the menisci is 3.6-4.9 times higher with conventional squats. PTS at the squats' lowest point minimally affects ACL stress but impacts menisci.

The single-bundle ACL reconstruction (ACLR) does not reproduce the biomechanics of the native ACL and increases stresses in most knee joint elements, according to the current study. Conventional squats are relatively safe for the ACL graft at their lowest point. Passing the half-squat position is the most dangerous point. Smith machine horizontal squats produce stress on the ACL graft several times higher than its estimated breaking load and dangerous stress levels on the ALL. During the rehabilitation following ACLR, it is advisable to prioritise the conventional squats over Smith machine squats until ligamentisation is complete.

Level III.

Altered axial biomechanics of the knee are recognized as a risk factor for non-contact anterior cruciate ligament (ACL) injury. However, the relationship of knee and segmental torsion to non-contact ACL and combined anterolateral ligament (ALL) injury is unclear. This study aims to determine the relationship of knee and segmental torsion to non-contact ACL injury and to explore their relationship with ALL injuries.

We divided 122 patients with arthroscopically confirmed non-contact ACL injuries into an ACL injury group (isolated ACL injury, 63 patients) and an ACL + ALL injury group (ACL combined with ALL injury,59 patients). Additionally, 90 normal patients with similar age, gender and body mass index (BMI) were matched as a control group. The tibial tubercle-trochlear groove (TT-TG) distance, distal femoral torsion (DFT), posterior femoral condylar torsion (PFCT) and proximal tibial torsion (PTT) were measured using magnetic resonance imaging (MRI). We assessed the differences between the groups using an independent samples t test and utilized receiver operating characteristic (ROC) curves to determine the cut-off value for the increased risk of ACL injury.

In patients with ACL injury, the measurements of the TT-TG (11.8 ± 3.1 mm), DFT (7.7° ± 3.5°) and PFCT (3.6° ± 1.3°) were significantly higher compared to the control group (9.1 ± 2.4 mm, 6.3° ± 2.7° and 2.8° ± 1.3°, respectively; P < 0.05), but the PTT did not differ between the two groups. The TT-TG, DFT and PFCT were not significantly larger in patients combined with ALL injury. ROC curve analysis revealed ACL injury is associated with TT-TG, DFT and PFCT.

Knee torsional alignment is associated with ACL injury, predominantly in the distal femur rather than the proximal tibia. However, its correlation with ALL injury remains unclear. These findings may help identify patients at high risk for non-contact ACL injury and inform the development of targeted prevention and treatment strategies.

Anterolateral ligament and medial collateral ligament injuries could happen concomitantly with anterior cruciate ligament ruptures. The anterolateral ligament is injured more often than the medial collateral ligament during concomitant anterior cruciate ligament ruptures although it offers less restraint to knee movement. Comparing the material properties of the medial collateral ligament and anterolateral ligament helps improve our understanding of their structure-function relationship and injury risk before the onset of injury.

Eight cadaveric lower extremity specimens were prepared and mechanically tested to failure in a laboratory setting using a hydraulic platform. Measurements of surface strains of superficial surface of each medial collateral ligament and anterolateral ligament specimen were found using three-dimensional digital image correlation. Ligament stiffness was found using ultrasound shear-wave elastography. t-tests were used to assess for significant differences in strain, stress, Young's modulus, and stiffness in the two ligaments.

The medial collateral ligament exhibited greater ultimate failure strain along its longitudinal axis (p = 0.03) and Young's modulus (p < 0.0018) than the anterolateral ligament. Conversely, the anterolateral ligament exhibited greater ultimate failure stress than the medial collateral ligament (p < 0.0001). Medial collateral ligament failure occurred mostly in the proximal aspect of the ligament, while most anterolateral ligament failure occurred in the distal or midsubstance aspect (P = 0.04).

Despite both being ligamentous structures, the medial collateral ligament and anterolateral ligament exhibited separate material properties during ultimate failure testing. The weaker material properties of the anterolateral ligament likely contribute to higher rates of concomitant injury with anterior cruciate ligament ruptures.

To assess the prevalence of and factors associated with medial collateral ligament (MCL) complex injuries on magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) tears.

Data were extracted from the Natural Corollaries and Recovery After ACL Injury (NACOX) multicenter longitudinal cohort study. Between May 2016 and October 2018, patients who presented to 1 of 7 health care clinics across Sweden with an ACL tear sustained no more than 6 weeks earlier and who were aged between 15 and 40 years at the time of injury were invited to participate. All the patients included in this study underwent MRI. The mean time from injury to MRI was 19.6 ± 15.2 days. An orthopaedic surgeon specializing in knee surgery and a musculoskeletal radiologist reviewed all MRI scans. Injuries to the superficial MCL (sMCL), deep MCL (dMCL), and posterior oblique ligament were identified. Stepwise forward multiple binary logistic regression analyses were used to evaluate patient characteristics (age, sex, body mass index, preinjury Tegner activity level, and activity at injury) and injuries on MRI (lateral meniscus [LM] injury, medial meniscus [MM] injury, pivot shift-type bone bruising, medial femoral condyle [MFC] bone bruising, and lateral femoral condyle [LFC] impaction) associated with the presence of MCL complex tears.

In total, 254 patients (48.4% male patients) with a mean age of 25.4 ± 7.1 years were included. The overall prevalence of MCL (sMCL and dMCL) injuries and isolated dMCL injuries was 16.5% (42 of 254) and 24.8% (63 of 254), respectively. No isolated sMCL injuries were found. Posterior oblique ligament injuries were found in 12 patients (4.7%) with MCL (sMCL and dMCL) injuries. An LM injury (odds ratio [OR], 3.94; 95% confidence interval [CI], 1.73-8.94; P = .001) and LFC impaction (OR, 2.37; 95% CI, 1.11-5.07; P = .02) increased the odds of having an MCL injury, whereas an MM injury (OR, 0.26; 95% CI, 0.12-0.59; P = .001) reduced the odds. Isolated dMCL injuries were significantly associated with MFC bone bruising (OR, 4.21; 95% CI, 1.92-9.25; P < .001) and LFC impaction (OR, 3.86; 95% CI, 1.99-7.49; P < .001).

The overall combined prevalence of MCL (sMCL and dMCL) injuries and isolated dMCL injuries in patients with ACL tears was high (16.5% + 24.8% = 41.3%). The presence of an LM injury and LFC impaction increased the odds of having an MCL injury, whereas the presence of an MM injury reduced the odds. MFC bone bruising and LFC impaction were associated with the presence of isolated dMCL injuries.

Level III, retrospective cohort study.

The association between injuries to the anterior cruciate ligament, medial collateral ligament, and medial meniscus (MM) has been known to orthopedic surgeons since 1936; O'Donoghue first used the term "unhappy triad" of the knee to describe this condition in 1950. Later studies revealed that involvement of the lateral meniscus is more common than MM in these cases, leading to a change in the definition. Recent studies have revealed that this triad may be primarily linked to knee anterolateral complex injuries. Although there is not a definite management protocol for this triad, we try to mention the most recent concepts about it in addition to expert opinions.