Successful complete artificial total hip arthroplasty for patients with Crowe type III or IV developmental dysplasia of the hip is challenging in clinical practice. This study aimed to explore the accuracy and effectiveness of preoperative digital design for patients with Crowe type III or IV developmental dysplasia of the hip. This case series study included patients with osteoarthritis secondary to developmental dysplasia of the hip who did not respond to conservative treatment and subsequently required total hip arthroplasty in Tianjin Third Central Hospital between January 2018 and February 2020. A total of 20 patients (5 males and 15 females) were enrolled, of whom 12 presented with Crowe type III and 8 with Crowe type IV developmental dysplasia of the hip. Total hip arthroplasty for each patient was successful. The implanted acetabular cups were one size (2 mm) smaller than the preoperatively designed size in four patients, and the implanted femoral stem prosthesis was one size (1 mm) larger than the preoperatively designed size in four patients with type IV DDH. The Harris scores differed significantly between preoperative and postoperative measurements (58.6 vs. 94.4; P = 0.016). No infection or joint dislocation was observed. Preoperative digital modeling may be used to predict the size of prosthesis required and location for implantation in patients undergoing total hip arthroplasty.

The number of artificial total hip revision arthroplasties is increasing yearly in China, and >50% of these cases have acetabular defects. Accurately locating and quantifying the bone defect is one of the current challenges of this surgery. Thus, the objective of the present study was to simulate acetabular implantation with the aid of Mimics 17.0 software (Materialise NV) in patients with loosened acetabular prosthesis, to evaluate the 'ideal acetabular center' and the 'actual acetabular center' to guide the choice of prosthesis and surgical method. From January 2017 to June 2021, the present study included 10 hips from 10 patients [seven men (seven hips) and three women (three hips)]. In all patients, the Mimics software was applied to simulate the dislocation of the femoral prosthesis and acetabular prosthesis implantation before surgery; calculate the height difference between the 'ideal acetabular center' and the 'actual acetabular center' to assess the bone defect; confirm the size of the acetabular prosthesis, abduction angle, anteversion angle and bone coverage of the acetabular cup; and measure the intraoperative bleeding and postoperative follow-up Harris score of the hip joint. After statistical analysis, the present study revealed that digital simulation assistance could improve the accuracy of hip revision acetabular prosthesis implantation, reduce postoperative shortening of the affected limb, especially for surgeons with relatively little experience in hip revision surgery, and greatly reduce the occurrence of complications such as hip dislocation because of poor postoperative prosthesis position.

Total hip arthroplasty (THA) with an acetabular component and an autogenous femoral head graft for acetabular reconstruction in developmental dysplasia of the hip was first described by Harris et al. in 1977. While a number of studies have addressed the aforementioned scenario over the last decades, most lack sufficient numbers and follow-up. As such, we analyzed long-term outcomes of THAs with femoral autograft for arthrosis secondary to hip dysplasia.

A systematic review was performed using a structured PubMed, Web of Science, Ovid MEDLINE, and Cochrane analysis, based on the PRISMA criteria. All original studies from 1977 to 2022 with a mean follow-up of 10 or more years were included. Methodological Index for Nonrandomized Studies (MINORS) were used for quality assessment.

A total of 26 studies with 1316 patients (87% females) undergoing 1543 THAs with femoral autograft (2 times neck graft, 24 times head graft) were included. Mean age was 52 years (range, 28-73) and the mean follow-up was 13 years (range, 9-18). The revision rate was 8.3% (n = 129), and 73% of revisions were for loosening. Rate of infection (0.5%) and dislocations (1%) were low. Radiographic analysis revealed 167 loose acetabular components (11%) and 118 cases of graft resorption (7.6%). Mean Harris Hip Score increased from 42 to 85. Mean MINORS score was 11, and no study was level of evidence I or II.

Femoral autograft with THA may be a viable long-term option for hip reconstruction in developmental dysplasia of the hip. However, moderate loosening rates and low level of evidence must be acknowledged before drawing the final conclusions.

Therapeutic Level III.

Developmental dysplasia is challenging to treat with total hip arthroplasty via the direct anterior approach (DAA). Reconstructing the former anatomy while restoring the acetabular bone stock for future revisions in this young patient collective combined with the known advantages of the DAA would be desirable. The purpose of this study was to analyze the feasibility, radiographic outcome and clinical outcome of primary uncemented total hip arthroplasty with bulk femoral head autograft for acetabular augmentation through a DAA with a minimal follow-up of 12 months.

A retrospective, consecutive series from March 2006 to March 2018 of 29 primary total hip arthroplasty with acetabular augmentation with bulk femoral head autograft through a direct anterior approach was identified. All complications, reoperations and failures were analyzed. Radiographic and clinical outcome was measured.

24 patients (29 hips) with a mean age of 43 (18-75) years and a mean follow-up of 35 months (12-137) were included. Surgical indication was secondary osteoarthritis for developmental dysplasia of the hip (Hartofilakidis Grade A (n = 19), B (n = 10)) in all cases. We noted no conversion of the approach, no dislocation and no acetabular loosening. The center of rotation was significantly distalized by a mean of 9 mm (0-23) and significantly medialized by a mean of 18 mm (6-29). The bone graft was fully integrated after 12 months in all cases.

Acetabular reconstruction with femoral head autograft in primary THA through a direct anterior approach seems to be a reliable option for the treatment of secondary osteoarthritis in patients with DDH Hartofilakidis grade A and B. Prospective cohort studies with a large sample population and a long-term follow-up are necessary to confirm our findings.

DDH with coxarthrosis causes significant deformity and bone deficiency. Various reconstructive techniques have been proposed to treat developmental dysplasia of the hip. However, the existing literature has not yet reached a consensus on the best technique regarding long-term survival.

This study aims to evaluate the long-term survival of uncemented hydroxyapatite (HA) coated acetabular components augmented with a femoral head autograft.

We retrospectively reviewed the cases of 31 hips in 29 patients (24 female, 5 male, mean age 45.06 years) treated with HA-coated cementless components and femoral head autograft between 2000-2008 with a minimum follow-up of 10 years. Graft resorption, cup loosening and the anatomical hip centre were determined. Functional outcomes were calculated using the Harris Hip Scoring system. The survival of the acetabular component was evaluated using the Kaplan-Meier method.

In 24 hips (77,4%), we reconstructed the hip centre anatomically. The remaining cups had variable deviations from the anatomical rotation centre. Only one patient required revision due to loosening. Survival analysis revealed 96.8% survival at 10 years. The mean Harris Hip Score was 39.23 preoperatively and 84.77 at final follow-up. There was no statistical correlation between revision and any of the measured parameters.

Acetabular reconstruction with a femoral head autograft allows for anatomical cup positioning, early structural support and increases bone stock for future revisions. Although our prior cemented cup study showed that anatomical cup orientation is critical, this study demonstrated the absence of a correlation between implant failure and cup positioning, suggesting that HA-coated cementless cups are more stable and forgiving.

HA-coated acetabular cups augmented with femoral head autograft provided long-term, reliable and durable cup fixation in dysplastic hips of young adults.

The accuracy of using 2-dimensional anteroposterior pelvic radiography to assess acetabular cup coverage among patients with developmental dysplasia of the hip after total hip arthroplasty (THA) remains unclear in retrospective clinical studies. A group of 20 patients with developmental dysplasia of the hip (20 hips) underwent cementless THA. During surgery but after acetabular reconstruction, bone wax was pressed onto the uncovered surface of the acetabular cup. A surface model of the bone wax was generated with 3-dimensional scanning. The percentage of the acetabular cup that was covered by intact host acetabular bone in vivo was calculated with modeling software. Acetabular cup coverage also was determined from a postoperative supine anteroposterior pelvic radiograph. The height of the hip center (distance from the center of the femoral head perpendicular to the inter-teardrop line) also was determined from radiographs. Radiographic cup coverage was a mean of 6.93% (SD, 2.47%) lower than in vivo cup coverage for these 20 patients with developmental dysplasia of the hip (P<.001). However, both methods yielded highly correlated measurements for cup coverage (Pearson r=0.761, P<.001). The size of the acetabular cup (P=.001) but not the position of the hip center (high vs normal) was significantly associated with the difference between radiographic and in vivo cup coverage. Two-dimensional radiographically determined cup coverage conservatively reflects in vivo cup coverage and remains an important index (taking 7% underestimation errors and the effect of greater underestimation of larger cup size into account) for assessing the stability of the cup and monitoring for adequate ingrowth of bone. [Orthopedics. 2018; 41(1):e46-e51.].

Recommendations for minimum cup coverage based on anteroposterior radiographs are widely used as an intraoperative guide in total hip arthroplasty for patients with developmental dysplasia of the hip. The purpose of this study was to examine the validity of two-dimensional (2D) measurement of coverage with three-dimensional (3D) coverage and to identify parameters for determining the 3D coverage during surgery.

We developed a technique to accurately reproduce the intraoperative anatomic geometry of the dysplastic acetabulum and measure the 3D cup coverage postoperatively. With this technique, we retrospectively analyzed the difference and correlation between 2D and 3D measurements of native bone coverage in 35 patients (45 hips) with Crowe II or III DDH. Linear regression analysis was performed to examine the intraoperative parameters related to coverage. The mean follow-up period was 7.64 years (range, 6.1-9.5 years).

There was a significant difference and a fair correlation between 2D and 3D measurements. The 2D measurement underestimated the 3D cup coverage by approximately 13%. An excellent linear relationship was noted between the 3D coverage/uncoverage and the height of the uncovered portion (R² = 0.8440, P < .0001). There was no case of loosening or revision during the follow-up.

Current minimum cup coverage recommendations based on 2D radiograph measurements should not be used as a direct intraoperative guide. The height of the uncovered portion is a useful parameter to determine the 3D coverage during surgery.

When performing total hip arthroplasty (THA) on a dysplastic hip, proper positioning of the acetabular component may not allow for more than 70% coverage. Structural support in the form of an autograft or a high porosity metal augment may be necessary. The purpose of the study was to investigate the value of preoperative templating and deformity classification in predicting cup coverage and the need for structural support.

65 cases of THA for DDH were retrospectively analysed. 2 observers independently classified each dysplastic hip according to Hartofilakidis and determined the extent of cup coverage via templating software on preoperative digital AP pelvic radiographs.

Weighted kappa interobserver agreement was 0.68 for cup coverage and 0.76 for Hartofilakidis type. Structural support was necessary in 10 hips. No structural support was necessary in Hartofilakidis type 1, dysplasia cases. However, 27-30% of cases with type 2 or type 3 dysplasia required structural support. All cases with templated cup coverage of 65% or less required structural support. Templated coverage within 65-75% and over 75% resulted in 20% and 10% of patients receiving structural augmentation, respectively.

Preoperative planning for THA in the setting of hip dysplasia is crucial and can provide valuable insight to the need for column augmentation. However, the 3-D severity of the deformity may be underestimated in the 2-D radiographs.

The purpose of this study was stimation of optimal percentage of lateral uncoverage of the acetabular component during total hip arthroplasty for patients with severe developmental hip dysplasia.

Mathematical computer modeling based on the finite element technique and the mechanical experiment were performed. Critical values of uncoverage enabling safe primary fixation of acetabular component were estimated in designed models.

Using the finite element technique and the mechanical experiment on pelvis models, a possibility of mounting an acetabular component with moderate uncoverage within 25% without screws and with significant uncoverage to 35% with an additional two-screw fixation was demonstrated.

This study provides additional guidance on optimal acetabular uncoverage assessment and fixation methods of surgeons performing THA on patients with DDH.

To assess whether computed tomography (CT)-based 3-dimensional (3D) computerized pre-operative planning is accurate and reliable in patients with high-riding dislocation developmental dysplasia of the hip (DDH) undergoing total hip arthroplasty (THA).

Between September 2009 and February 2011, a prospective study with an inbuilt means of comparing predictive techniques in 20 patients (20 hips) with high-riding dislocation DDH was undertaken. All patients had pre- and post-operative CT scans, data from which were transferred digitally to Mimics software. 3D pre-operative planning to predict the acetabular component size, hip rotation center position and acetabular component coverage was performed using Mimics software. The results and post-operative course were compared with those of the traditional acetate templating technique.

Using 3D computerized planning, 14/20 components (70%) were predicted exactly and 6/20 (30%) within one size, whereas with the conventional acetate templating technique, 5/20 components (25%) were predicted exactly, 9/20 (45%) within one size and 6/20 (30%) within two or more sizes. There was a strong correlation between the 3D computerized planned acetabular component size, hip rotation center distance, acetabular component host coverage and that found postoperatively. Five patients were considered to need structural bone graft on the basis of 3D computerized planning; this was highly coincident with the intraoperative findings in all five cases.

CT-based 3D computerized pre-operative planning using Mimics software is an accurate and reliable technique for patients with high-riding dislocation DDH undergoing THA.

We previously reported the five to twelve-year results of total hip arthroplasty with an uncemented acetabular component and an autogenous femoral head graft in forty-four consecutive hips with developmental dysplasia. The goal of the present study was to report the implant survival rate, status of bone grafts, and clinical outcomes in thirty-five of these hips (in twenty-nine patients) followed for a mean of 21.3 years. Functional, radiographic, and survivorship results were examined. Radiographic analysis revealed an average cup inclination angle of 43° and a mean arc of cup coverage by the graft of 30°. The twenty-year survivorship free from acetabular revision was 66% (twelve acetabular revisions; eight since our previous report). Of the twelve revisions, nine were for liner wear and/or osteolysis, one was for a liner fracture, one was for aseptic loosening, and one was for instability. All bone grafts healed to the pelvis. The graft facilitated revision cup placement as no additional structural grafts or metal augments were required. We concluded that an uncemented porous-coated socket used in conjunction with a bulk femoral head autograft provides good long-term fixation and restores bone stock.

Socket fixation in patients with acetabular dysplasia can be technically demanding but the use of structural grafts can help to reconstruct the original center of hip rotation. Because reported survival rates differ, construct survival seems to depend on the technique of graft preparation and fixation.

What is the survivorship of cemented sockets with acetabular roof graft in patients with severe acetabular dysplasia? Do clinical scores equal those of patients without acetabular grafting?

We retrospectively reviewed 62 patients (74 hips) who had undergone cemented THA with acetabular roof graft. Mean age at surgery was 45 years (range, 19-71 years). Revisions and radiographic failures were determined and clinical scores (Oxford, SF-12) were obtained and matched to a control group. Kaplan-Meier analysis was used to determine survivorship at a minimum followup of 5 years (mean, 10.4 years; range, 5-16 years).

Survivorship for all-cause revision was 98% (95% CI, 92.5%-100.0%) at 10 years followup. Two hips were revised for aseptic acetabular loosening and one hip for polyethylene wear. All grafts incorporated and no additional radiographic loosenings were seen. Patients with grafting had higher Oxford scores compared with the control group but other scores were equal.

In contrast to reported series and the common use of cementless cups in patients with developmental dysplasia of the hip, we found high survivorship of cemented sockets with roof graft in severe acetabular dysplasia at a mean followup of more than 10 years. These patients showed higher Oxford scores than patients in a control group. This technique that restores bone stock is a reasonable solution for often young patients with dysplasia.

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Preoperative planning is essential to define anatomy, clarify the operative approach and exposure, and ensure that suitable implants are available.Concerns exist regarding the long-term effectiveness and safety of hip resurfacing arthroplasty for the young dysplastic hip.In light of current evidence, concerns exist regarding the use of metal-on-metal articulations for hip arthroplasty in the young dysplastic hip.The ideal bearing surface is not known, although the longest data available support the use of metal-on-polyethylene.

Total hip arthroplasty is the procedure of choice for most patients with advanced, symptomatic osteoarthritis due to congenital dysplasia of the hip. However, the complexity of arthroplasty is significantly increased because of anatomic abnormalities associated with dysplasia of the hip. In addition the relatively young age of patients may affect survival of the implant. From a biomechanical standpoint the primary surgical objective is reconstruction of the anatomical center of rotation. Independent of the pelvic bone stock the socket should be located as near as possible to the anatomical acetabular location. There are various operative strategies to ascertain sufficient stability of the socket. The anterolateral deficiency of the acetabulum can be reconstructed by bulk femoral autografting or bone impaction grafting. Furthermore controlled perforation of the medial wall or implantation of reinforcement rings and oval sockets have been described. Cementless, biological socket fixation shows superior long-term results compared to cemented cups, especially in these young patients. The location of the reconstructed acetabulum and the desired leg length influence the type of femoral reconstruction and in some cases femoral shortening is required. In this article endoprosthetic reconstructive options for developmental dysplasia of the hip are discussed depending on the femoral and acetabular deformity.

We evaluated the effect of the inclination angle, position, and containment of 53 cementless cups inserted in patients with congenital hip disease (CHD), after a minimum of 10 years of follow-up. The polyethylene wear rate was significantly greater when the cup was placed in more than 45° inclination (P=.045) or if the cup was placed lateral to the teardrop position by more than 25 mm (P=.001). Aseptic loosening of the femoral component was significantly greater when the cup was placed more than 25 mm superiorly to the teardrop (P=.049). Cup placement of more than 25 mm lateral to the teardrop affected significantly periacetabular osteolysis (P=.032). In CHD cases, it is preferable to avoid excessive vertical inclination, lateral, and superior placement of cementless cups in an attempt to obtain better containment.

Deficient acetabula associated with acetabular dysplasia cause difficulty achieving adequate coverage of the acetabular component during THA. Autografting with the removed femoral head has been used for several decades to achieve better coverage, but the long-term benefits of this technique remain controversial, with some series reporting high rates of graft resorption and collapse.

We evaluated the fate of bulk femoral head autograft for acetabular reconstruction in cementless THA for developmental hip dysplasia.

We retrospectively reviewed 70 patients (83 hips) (68 women, two men) with a mean age of 57 years at index surgery. According to the classification of Crowe et al. for hip dysplasia, 10 hips were classified as Type I, 45 as Type II, 19 as Type III, and nine as Type IV. Minimum followup was 9 years (mean, 11 years; range, 9-14 years).

We observed no collapsed grafts. In all patients we observed disappearance of the host-graft interface and appearance of radiodense bands in the grafts bridging host iliac bone and at the lateral edges of the acetabular sockets; remodeling with definite trabecular reorientation was seen in 90%. The 10-year survival rate without acetabular revision for any reason was 94%. The mean Merle d'Aubigné and Postel hip score improved from a mean of 9.1 preoperatively to 17.2 at last followup.

Cementless THA combined with autologous femoral bone graft in patients with developmental dysplasia resulted in a high rate of survival. Structural bone grafting achieved a stable construct until osseointegration occurred. We believe the radiodense bands represent a radiographic sign of successful completion of repair of the deficient acetabulum. Congruous and stable contact of the cancellous portion of the graft to the host bed by impaction and use of improved porous cementless sockets may be associated with successful socket survival.

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

This study was designed to evaluate the midterm results of hybrid total hip arthroplasty in a consecutive series of 45 Chinese patients with osteoarthritis secondary to dysplastic hip. The average follow-up was 6.6 years. A total of 24 hips were classified as dysplasia, 20 hips as low dislocation, and 13 hips as high dislocation. The preoperative Harris score was 46.19 +/- 18.01, which improved to 91.78 +/- 3.52 at the final follow-up. The rate of polyethylene liner wear was 0.27 mm/y. Osteolysis was identified around 5 acetabular components and 13 femoral components. With the use of loosening or revision as the end point for failure, the survival rate was 1.0. We suggest that hybrid total hip arthroplasty in Chinese developmental dysplasia of hip patients has favorable results at midterm follow-up, even though their lifestyle includes more deep flexion of the hip. There is no significant difference of postoperative Harris score with increasing severity of dysplasia.

We describe the problems with positioning the hip center according to the severity of dislocation in 97 cementless total hip arthroplasty for developmental dysplasia of the hip. The mean location of the hip center from the interteardrop was 30.4 +/- 8.7 mm horizontally and 23.4 +/- 5.4 mm vertically. The presence of a limp correlated with a superior placement of the cup. Four cups were revised, 2 of which with a significant high hip center. The survival rate of the acetabular component was 95% at 12 years. Craniopodal repositioning was easy in class 1. In class 2, the cup was the largest. In class 3, the greatest variations of the hip center were found. In class 4, the smallest implants were necessary for positioning in the true acetabulum.

Untreated hip dysplasia predisposes young adults to early arthritis. Varus rotational osteotomies are considered one option to delay or eliminate total hip arthroplasty. We update a report from 1991 by retrospectively reviewing 40 of 48 patients (83.3%) who had 45 varus rotational osteotomies from 1971 to 1986 with a minimum followup of 15 years (mean, 22.6 years; range, 15-34 years). Results were assessed using Hospital for Special Surgery hip scores and radiographic parameters. The average age of the patients at followup was 57.2 years (range, 38-81 years). Fourteen patients (35%) (16 hips) had no additional procedures at 21.2 years followup (range, 15-27 years). The average Hospital for Special Surgery hip score was 33.7 with a Tönnis scale of 1.7 (mild-moderate osteoarthritis). Twenty-six patients (65%) (29 hips) had total hip arthroplasties an average of 9.75 years (range, 2-27 years) after varus rotational osteotomy. As in the initial study, the degree of preoperative osteoarthritis was a predictive value for success of the varus rotational osteotomy. Additionally, younger patients with minimal hip subluxation and osteoarthritis, and a better preoperative Hospital for Special Surgery hip score were predictors of success.

Modern hip resurfacing implants may increase stability and preserve more bone than conventional total hip arthroplasty. The purpose of this retrospective study was to analyze the mid-term results in a consecutive series of middle-aged patients with developmental dysplasia of the hip treated with hybrid resurfacing joint arthroplasty.

Metal-on-metal hip resurfacing was performed in fifty-one patients (fifty-nine hips), forty-two of whom were female and nine of whom were male. The average age at the time of surgery was 43.7 years. Radiographic and clinical data were collected at six weeks, at three months, and at yearly follow-up visits. Seven hips had Crowe type-II developmental dysplasia of the hip and fifty-two had type-I.

The follow-up period ranged from 4.2 to 9.5 years (average, 6.0 years). Initial stability was achieved in all but three hips. The clinical outcomes, as rated with the University of California at Los Angeles (UCLA) hip score, improved significantly compared with the preoperative ratings. On the average, the pain rating improved from 3.2 to 9.3 points; the score for walking, from 6.0 to 9.7 points; the score for function, from 5.7 to 9.6 points; and the score for activity, from 4.6 to 7.3 points (all p = 0.0001). The mean Short Form-12 (SF-12) mental score increased from 46.6 to 53.5 points, and the mean SF-12 physical score increased from 31.7 to 51.4 points (both p < 0.0001). The mean postoperative Harris hip score was 92.5 points. On the average, the range of flexion improved from 106 degrees to 129.6 degrees ; the abduction-adduction arc, from 41.9 degrees to 76.9 degrees ; and the rotation arc in extension, from 32.1 degrees to 84.8 degrees (all p = 0.0001). Four patients delivered a total of six healthy babies since the time of implantation of the prosthesis. Radiographic analysis showed a decrease in the mean body weight lever arm from 118.5 mm preoperatively to 103.9 mm postoperatively (p = 0.007). There were five femoral failures requiring conversion to a total hip arthroplasty. One hip showed a radiolucency around the metaphyseal femoral stem. There were no complete acetabular radiolucencies, and all sockets remained well fixed.

The mid-term results of metal-on-metal resurfacing in patients with Crowe type-I or II developmental dysplasia of the hip were disappointing with respect to the durability of the femoral component. However, the fixation of the porous-coated acetabular components without adjuvant fixation was excellent despite incomplete lateral acetabular coverage of the socket. More rigorous patient selection and especially meticulous bone preparation are essential to minimize femoral neck fractures and loosening after this procedure.

Arthroplasty in developmental dysplasia of the hip joint raises technical problems related to the anatomy and age of the young patient. The purpose of this work was to report results obtained with a custom-designed cementless stem.

This study included 257 hips reviewed at mean 82 months (range 43-162 months). Mean patient age was 55 years (17-78), mean weight 67 kg (42-118), and mean height 164 cm (147-190). A standard imaging protocol was performed for all patients: AP pelvis in reclining position, AP and lateral views of healthy and pathological hip, AP view of entire lower limb in standing position, computed tomography of lower limb. La position of the greater trochanter and the lengthening necessary was determined from the preoperative films. Stem integration and migration as well as osteolysis were studied postoperatively. Femoral anteversion and the anteroposterior diameter of the paleoacetabulum were measured on the superposed computed tomographic images. Surgery was performed via a Watson-Jones approach to insert a noncemented cup hooked in the obturator foramen and implanted in the paleoacetabulum. The femur endomedullary cavity was prepared with a ream having the form of the definitive stem and the prosthetic neck was custom fit to match the desired lever arm and anteversion.

The series included 174 cases of dysplasia and 83 dislocations, 39% stage 1, 30% stage 2, 14% stage 3 and 17% stage 4. Mean lengthening was 39 mm. The mean helitorsion was 28 +/- 16 degrees and the mean anteroposterior diameter of the acetabulum was 51 mm. On average, the alpha correction in the prosthetic neck was -13.4 degrees (-71 degrees to +37 degrees). The Postel-Merle-d'Aubigné score improved from 10.4 points preoperatively to 16.7 points at last follow-up. Postoperative x-rays showed signs of osteointegration in 88% of cases, osteolysis in 5% and one case of stem impaction. Ten hips (3.9%) required revision for replacement (7 for an aseptic problem and 3 for sepsis). Survival was 94.7% at 13 years.

This study confirmed the anatomic modifications observed in patients with developmental hip dysplasia and the surgical problems they cause. There was no correlation between the degree of dislocation and the degree of helitorsion which is difficult to assess without a preoperative computed tomography. The survival rate at 13 years is encouraging in this population. The intramedullary portion of the cementless stem must be adapted to the dimensions of the femoral canal which decrease with increasing dislocation.

Studies of acetabular reconstruction with use of cement and bulk bone graft have demonstrated increasing rates of cup failure in patients with dysplastic hips seven years after total hip arthroplasty. Comparable data on the long-term results of bulk bone-grafting done in conjunction with cementless implants are limited. The aim of this study was to review the clinical and radiographic results of autologous bulk bone-grafting in conjunction with a cementless cup.

From 1987 to 1992, forty-seven patients (forty women and seven men, with an average age of 50.4 years) who had developmental dysplasia of the hip underwent fifty-six total hip arthroplasties and received a structural graft in combination with a cementless Harris-Galante type-I cup. All patients were followed prospectively. In fifty-five hips, implant migration was measured with single-image radiographic analysis.

After an average duration (and standard deviation) of 10.2 +/- 2.9 years, three patients (four hips) had died. In the surviving patients, four implants had been revised and two had radiographic evidence of loosening. With use of revision and loosening as end points, the eleven-year survival rates were 91.6% and 88.9%, respectively. Of the fifty implants that had no loosening, fourteen had measurable cup migration, thirty-five had no migration, and one implant could not be measured. All migrations but one were progressive. With loosening used as the end point, the survival rate at eleven years was 100% for the implants with no migration; however, the survival rate for the cups that had migrated was 69.3% (p = 0.0012).

The eleven-year survival rate for the spherical press-fit cups in combination with bulk bone-grafting is satisfactory, given the complexity of these reconstructions. However, the difference between the survival of the implants that had migrated and those that had not was significant. We expect that the thirteen implants with progressive acetabular migration at the time of the latest follow-up are at risk for loosening, which will increase the revision rate for this series in the coming years.

Twenty-eight primary total-hip arthroplasties in 23 patients performed with autogenous femoral head bone graft augmentation for developmental hip dysplasia were retrospectively reviewed at 8 to 15 years. Five sockets were revised for different reasons. At revisions, 3 grafts were healed, the other 2 had substantial resorption. Immediately postoperatively, the mean medial to lateral graft thickness at the level of the superior border of the socket was 33 mm. Radiographs a mean of 4.8 years after operation demonstrated this thickness decreased by a mean of 1 mm (range, 0-10 mm). At 11 years (range, 8-15 years), radiographs in unrevised hips showed no cases of substantial further graft resorption.

We describe a new technique of reconstruction of the deficient acetabulum in cementless total hip arthroplasty. The outer iliac table just above the deficient acetabulum is osteotomised and slid downwards. We have termed this an iliac sliding graft. Between October 1997 and November 2001, cementless total hip arthroplasty with an iliac sliding graft was performed on 19 patients (19 hips) with acetabular dysplasia. The mean follow-up was 3.4 years (2 to 6). The mean pre-operative Harris hip score was 45.1 which improved significantly to 85.3 at the time of the final follow-up. No patient had post-operative abductor dysfunction. Incorporation of the graft was seen after two to three months in all patients. Resorption of the graft and radiolucencies were infrequent. This technique is a useful alternative to femoral head autografting when the patient's own femoral head cannot be used.

We radiographically investigated 36 hips in 34 patients with osteoarthritis of the hip who had undergone total hip arthroplasty. Their mean age was 59.2 years (range 36-79 years), and the mean follow-up period was 11.2 years (range 10-14 years). The long-term outcome and the chronological changes in the bulk autograft were examined. The acetabular component of the prosthesis was a Lord-type threaded cup with a smooth surface. At follow-up, bone absorption was minor in 17 joints, moderate in 11, and major in 8. The hips with graft coverage of >==20% (group A) had a significantly higher loosening rate than hips with coverage of <<20% (group B) ( P << 0.05). The cup position changed markedly in group A. Our findings indicate that graft coverage should be less than 20% when a bulk graft is used together with a smooth-surfaced cementless cup.

Total hip arthroplasty is the procedure of choice for most patients with symptomatic end-stage coxarthrosis secondary to hip dysplasia. The anatomic abnormalities associated with the dysplastic hip increase the complexity of hip arthroplasty. When pelvic bone stock allows, it is desirable to reconstruct the socket at or near the normal anatomic acetabular location. To obtain sufficient bony coverage of the acetabular component, the socket can be medialized or elevated, or a lateral bone graft can be applied. Uncemented acetabular components allow biologic fixation with potentially improved results compared with cemented cups, especially in young patients. The location of the acetabular reconstruction and the desired leg length influence the type of femoral reconstruction. Cemented and uncemented implants can be used in femoral reconstruction, depending on the clinical situation. Femoral shortening is required in some cases and can be performed by metaphyseal resection with a greater trochanteric osteotomy and advancement or by a shortening subtrochanteric osteotomy. The results of total hip arthroplasty demonstrate a high rate of pain relief and functional improvement. The long-term durability of cemented total hip arthroplasty reconstruction in these patients is inferior to that in the general population. The results of uncemented implants are promising, but only limited early and midterm data are available.

Anterolateral acetabular bone deficiency is one of the technical problems associated with total hip arthroplasty in patients with developmental hip dysplasia. The purpose of this study was to evaluate the results of one method of acetabular reconstruction for hip dysplasia-placement of an uncemented socket in conjunction with a bulk femoral head autograft.

Forty-four hips in thirty-five patients (twenty-nine female and six male; average age, thirty-nine years) with developmental hip dysplasia were treated with primary total hip arthroplasty with use of an uncemented porous-coated titanium cup fixed with screws and an autogenous bulk femoral head graft. The patients were followed clinically in a prospective fashion for five to 12.3 years (mean, 7.5 years), and radiographs were analyzed retrospectively.

Four acetabular components were revised: two, because of severe polyethylene wear and osteolysis; one, because of aseptic loosening; and one, because of fracture of the acetabular shell. The mean Harris hip score for the unrevised hips improved from 51 points preoperatively to 91 points postoperatively. No unrevised socket had definite radiographic evidence of loosening. Forty-three of the forty-four hips had no radiographic evidence of resorption of the graft or had radiographic evidence of resorption limited to the nonstressed area of the graft lateral to the edge of the cup.

This method of reconstruction provided reliable acetabular fixation and appeared to restore acetabular bone stock in patients with developmental hip dysplasia. We use this technique for patients with moderate anterolateral acetabular bone deficiency requiring total hip arthroplasty.

Long-term clinical results of total hip arthroplasty for patients with developmental acetabular dysplasia of the hip have been reported, but placement of the femoral head center or cup orientation remains controversial, especially with a severe anterolateral shallow acetabulum or dislocated femoral head. Results of 41 Müller and 34 Harris Design 2 cemented total hip arthroplasties were evaluated for developmental dysplasia of the hip. The femoral head center and acetabular cup inclination angle were measured from the interteardrop line. Linear wear and wear direction were measured using the Livermore technique. The best position of the femoral head center was less than 35 mm vertically from the interteardrop line and 25 mm laterally from the teardrop. Femoral head center analysis showed that hips with the cup in a lateral and superior cup position all were revised, but a superior and medial position combined with a cup inclination angle less than 40 degrees did not require revision. Hips with a cup inclination angle more than 45 degrees had superior and lateral penetration patterns of the polyethylene. However, hips with an inclination angle less than 35 degrees and medial placement had medial head penetration patterns. With these all-polyethylene monolithic cemented cups, regardless of the femoral head diameter or cup thickness, better long-term results occurred with a cup inclination angle of 40 degrees or less and medial position of the cup.

Uncemented Zweymueller total hip prostheses were implanted in 35 dysplastic or dislocated hips in 33 patients. Sixteen hips were dislocated and 19 hips were dysplastic; in 12 hips, an intertrochanteric or pelvic osteotomy was performed in early childhood. In all cases, the titanium screw socket was implanted at the level of the original cotyloid cavity. Osteotomy of the greater trochanter, shortening osteotomy, or roof acetabuloplasty were not performed. In cases in which the femoral cavity was too narrow for the Zweymueller stem, an anterolateral longitudinal window-shaped osteotomy was performed. In cases of severe dysplasia, cotyloid cavity bone grafts from the resected femoral head were placed medially to reinforce the acetabular bottom. Clinical and radiographic follow-up ranged from 3-8 years. Average Harris hip score improved from 47 points preoperatively to 86.2 points postoperatively. Complications included two primary anterior dislocations, two temporary femoral nerve pareses, and two deep vein thromboses. At longest follow-up evaluation, no revision was indicated in any of the hips. Satisfactory results in this series were attributed to careful patient selection, precise preoperative radiographic planning, and an operative technique that included implantation of the socket at the primary acetabulum and achievement of primary stability using press-fit fixation.

Long-term clinical results of Harris-Galante type prosthesis in total hip arthroplasty (THA) were evaluated in 27 hip joints of 25 patients (2 men and 23 women). Seventeen joints also received bone grafting on the acetabulum. Mean follow-up period was 11 years and 3 months. Clinical out-come was evaluated using the hip score of the Japanese Orthopaedic Association, and the score was good and stable during the monitoring period. Implant stability, bone changes around the implant, and the occupancy rate of the stem in the medullary space were radiologically examined. As a result of stem, there was subsidence in 3 joints and loosening in 6. There were no cases of cup loosening. A pedestal was found in 12 joints, and 4 of them which were associated with a radiopaque line had stem loosening. Among the 21 joints without loosening, 8 had a pedestal but they were not associated with a radiopaque line. The 2 joints which developed osteolysis did not have loosening. Stem loosening was related to the stem occupancy rate in the distal part of the medullary cavity. Postoperative stem occupancy rate could be an important indicator for long-term clinical results. Stems for cementless THA should be designed to have a high occupancy rate in the distal part, and stems should also be carefully chosen to meet individual differences.

Acetabular reconstruction with severe bone loss after failed total hip arthroplasty is a difficult problem. Defects were defined as major segmental and cavitary loss (type III anterior or posterior) or pelvic discontinuity (type IV). Seventeen cases were treated, of which 7 were type III and 10 were type IV. Bulk allograft was used in 16 of 17 cases, of which 7 were whole acetabular grafts, 2 were posterior segmental acetabular grafts, and 7 were femoral heads. Fourteen of 17 patients were female. The extensile triradiate approach was used in 12 cases. Long pelvic bone plates were applied to the posterior column and anterior brim of the pelvis in most cases. Allografts united to host-bone in 15 cases. Average follow-up was 83 months. The overall revision rate was 47%, of which 3 of 7 press-fit and 2 of 10 cemented cups had failed. The dislocation rate for the extensile approach was 50%; 2 patients had excisional arthroplasty for infection, and 2 patients had exploration of the sciatic nerve for release from migrating pelvic plate screws. Because of the overall poor results, this approach cannot be recommended for general use.

Twenty-four hip replacements were performed with use of a medial protrusio technique to stabilize the fit of a hemispherical metal shell in the acetabulum in nineteen patients who had dysplasia of the hip. All of the hips were followed for a minimum of five years (average, seven years; range, five to thirteen years). Six of the hips were type I, seven were type II, eight were type III, and three were type IV according to the criteria of Crowe et al. The acetabular cup was implanted with the medial aspect of its dome beyond the Kohler line (drawn from the ischium along the ilioischial line) in all hips. An autogenous graft sculpted from the femoral head was used to cover 15 to 30 percent of the superolateral portion of the cup in one type-I hip, four type-III hips, and one type-IV hip. The need for these six bone grafts could have been avoided by reaming two to three millimeters more medially or by allowing 20 percent of the superolateral portion of the cup to be uncovered. Sixty to 84 percent of each bone graft was resorbed, effectively leaving the superolateral portion of the cup uncovered. The amount of the surface of the cup that was beyond the Kohler line averaged 41 percent for the six type-I hips, 43 percent for the seven type-II hips, 41 percent for six of the type-III hips, and 44 percent for one of the type-IV hips. Crossing of the ilioischial and iliopubic lines was noted on the radiographs of two type-III and two type-IV hips. Radiographs of two type-I hips and one type-II hip showed 7 to 17 percent of the surface of the dome of the cup through the internal pelvic wall (beyond the iliopubic line). None of the twenty-four metal shells were revised. A reoperation was performed on two hips to exchange a worn polyethylene insert, and three femoral components that had been fixed without cement were revised because of mechanical loosening. Wear averaged 0.26 millimeter per year in the fourteen hips that had a titanium femoral head and 0.09 millimeter per year in the nine hips that had a cobalt-chromium femoral head. The remaining hip had a ceramic femoral head, and the wear rate was 0.09 millimeter per year. The medial protrusio technique is a predictable, reproducible method for obtaining fixation of a porous-coated, hemispherical acetabular component in a dysplastic acetabulum. The technique permits the use of a porous-coated (bone-ingrowth) component; avoids the use of support bone graft and thereby reduces the operative time; facilitates rehabilitation by permitting earlier weight-bearing of the hip; and permits the use of a modular bearing surface, which may allow future exchange of only this surface rather than revision of the entire acetabular component because of excessive wear.

The purpose of our study was to examine the clinical and technical problems associated with reconstruction of the hip in patients who had congenital dysplasia and to offer recommendations for their solution. We reviewed the records on 123 consecutive total hip arthroplasties that had been performed by one of us (M. E. M.), between 1981 and 1986, for the treatment of coxarthrosis due to congenital dysplasia of the hip. A minimum of five years of follow-up was required for inclusion in the study. The study group consisted of seventy patients who had had a total of eighty-seven reconstructions. According to the classification of Crowe et al., eleven hips had type-IV acetabular dysplasia; sixty-five, type-II; and eleven, type-II. Acetabular reconstruction was performed with use of the Müller acetabular roof-reinforcement ring and a polyethylene cup, which was inserted with cement. Autologous graft from the femoral head was used in forty-two hips. Femoral reconstruction was performed with use of the Müller straight-stem component for congenital dysplasia of the hip in eighty hips and with use of a standard Müller straight-stem component in seven hips. At an average of 9.4 years (range, five to fifteen years) postoperatively, the result was described as excellent for sixty hips (69 per cent), as good for twenty-three (26 per cent), as fair for two (2 per cent), and as poor for two. Nine (10 per cent) of the hips had been revised. One revision had been performed because of aseptic loosening of the acetabular component; one, because of aseptic loosening of the femoral component; one, because of aseptic loosening of both components; and six, because of infection. Of the unrevised hips, three had had superior migration of the acetabular component of less than five millimeters, and mild protrusion had developed in one. Two hips had a continuous radiolucent line around the acetabular construct. Two hips had had subsidence of the femoral stem of less than three millimeters; one had a complete, non-progressive radiolucent line at the bone-cement interface; and four had a radiolucent line at the proximal part of the bone-cement interface. Six hips had evidence of endosteal osteolysis. Six hips had grade-III or IV heterotopic ossification according to the system of Brooker et al. These results compare favorably with others in the literature. We recommend restoration of the anatomical hip center with the use of an acetabular roof-reinforcement ring and a polyethylene cup inserted with cement for the reconstruction of a deficient acetabulum. The acetabular reinforcement ring prevents resorption of bone graft and migration of the cup, which are major causes of failure of the cup in patients who have had a reconstruction of a deficient acetabulum. Bone graft should be used medially and superiorly as needed to augment bone stock notably. Cement should not be used to fill acetabular defects as we believe that it contributes to aseptic loosening.

Acetabular reconstruction with bulk structural autogenous grafts and allografts from the femoral head in complex total hip arthroplasty was highly successful at an average of five years postoperatively but was much less so by 11.8 years. To assess the longer-term fate of such grafts, we reviewed the results of eighty-one consecutive total hip arthroplasties performed by the senior one of us with use of these grafts. Nine hips in nine patients who had died and two hips that were infected in two patients were excluded. Therefore seventy hips (sixty-two patients) were included in this study. The average duration of follow-up was 16.5 years (range, 14.1 to 21.4 years). Sixty-one arthroplasties were performed to treat various forms of congenital dysplasia. Fifteen arthroplasties, ten of which were revision operations, were performed with allograft, and fifty-five were performed with autogenous graft. The average age of the patients at the time of the index operation was 45.2 years (range, sixteen to sixty-nine years). All of the sockets, which had an average outer diameter of forty millimeters (range, thirty-four to fifty millimeters), were inserted with cement. The average coverage of the acetabular component by the bulk graft was 49 per cent (range, 15 to 100 per cent). All of the grafts united. At the latest follow-up examination, twenty-five acetabular components (36 per cent) had been revised for aseptic loosening, eighteen (26 per cent) had radiographic evidence of loosening, and twenty-seven (39 per cent) were rigidly fixed and in place. The average Harris hip score for the hips in which the implant remained rigidly fixed was 74 points, while that for the hips in which the implant was loose but had not been revised was 69 points. Nine of the fifteen acetabular components supported by allograft and sixteen (29 per cent) of the fifty-five supported by autogenous graft were revised (p = 0.03). However, the total rate of acetabular components that were either loose or revised was ten of fifteen and thirty-three (60 per cent) of fifty-five, respectively. This difference was not significant (p = 0.4), with the numbers available. Regression analysis revealed that a younger age at the time of the operation and the extent of coverage of the acetabular component by the graft were associated with the need for revision. Twenty-one (78 per cent) of the twenty-seven acetabular components that remained rigidly fixed were supported by graft over less than 50 per cent of the contact area, while only nine (36 per cent) of the twenty-five that were revised were so supported (p < 0.05). None of the nine acetabular components with 30 per cent of the contact area or less covered by graft were revised. In nineteen of the twenty-two revisions of the acetabular component performed after the index operation, the socket was inserted without cement; the average outer diameter of the socket was fifty-three millimeters (range, forty to fifty-eight millimeters). Both the structural autogenous grafts and the structural allografts used in acetabular reconstruction in total hip replacement functioned well for the initial five to ten years. By an average of 16.5 years, nine of the fifteen hips treated with allograft and sixteen (29 per cent) of the fifty-five treated with autogenous graft had been revised. The greater the extent of the coverage of the acetabular component by the graft, the greater the rate of late failure.

Few studies have examined the relationship between the severity of congenital dysplasia of the hip (CDH) and the clinical outcome of total hip arthroplasty. The authors have used a prospective design to study this question, using the Crowe grade to assess the severity of CDH. There were 71 patients with CDH operated on using the S-ROM total hip (Joint Medical Products, Stamford, CT); the control group was composed of 22 patients without CDH operated on using the same implant during the same period as the CDH patients. The patients with mild CDH did not have a different outcome from the patients without CDH with respect to Harris hip score or limp. The higher the Crowe grade, the more complications occurred. It was also found that the patients in whom the true acetabulum was not used had a significantly higher incidence of limp.

This study examines the effects of a superiorly placed hip center on the strength of the abductor muscles. A 3-dimensional computer model of the hip and the surrounding musculature was used to calculate the moment arms, forces, and moments generated when the hip abductor muscles are maximally activated. A representation of a hip prosthesis was implanted into the computer model with altered hip center positions and a range of prosthetic neck lengths. Analysis of these simulated hip replacements demonstrated that superolateral placement of the hip center (2 cm superior and 2 cm lateral) decreases the moment arms of the hip abductor muscles by an average of 28%. This decrease in moment arm cannot be restored by increasing prosthetic neck length, resulting in an unrecoverable loss of abduction strength with superolateral displacement. By contrast, a 2-cm superior displacement of the hip center changes the moment arms and force generating capacities of the abductors by less than 10% if prosthetic neck length is increased to compensate for decreased muscle length. The results of this study suggest that superior positioning of the hip center, without lateral placement, does not have major, adverse effects on abduction moment arms or force generating capacities when the neck length is appropriately increased.

The fate of autologous femoral head bone grafts in acetabular roof reconstruction for severely dysplastic hips was investigated in 25 patients (25 cementless total hip arthroplasties). Twenty patients were women and 5 were men, whose average age was 55 years old; their average followup was 58 months. The average Harris Hip Rating improved from a preoperative value of 49 points to a postoperative value of 85 points. Radiographic measurements did not indicate any vertical or horizontal socket migration >2 mm. The grafted bone was incorporated by an average time of 7 months, and the acetabular sclerosis had disappeared in 23 hips by 9.4 months. One year after operation, the grafted bone was reduced in size significantly. Radionuclide uptake at the site of the bone graft remained high for as long as 18 months after the operation, then normalized. The autologous acetabular bone grafts were incorporated completely and remodeled 18 months after surgery.

A series of 33 hips treated with cementless cups and structural autograft or allograft were reviewed at a minimum follow-up period of 5 years. Seventeen hips received a shelf autograft during primary hip arthroplasty and 16 received an allograft at revision. In the hips receiving autografts, the average preoperative hip score was 45.1 and the score at final review was 87.5, whereas in the revisions reconstructed with allografts, the average preoperative hip score was 44.4 and the score at final review was 82. Overall, only 2 of 33 hips were considered failures, giving a success rate of 94% at an average follow-up period of 6.6 years. Leg-length discrepancy greater than 2 cm was seen in 27 of 33 hips, and at final review only 4 of 33 hips had a leg-length discrepancy greater than 2 cm. All grafts united to host-bone. Resorption, when seen, was minor, with only three grafts showing moderate resorption. Our data support the use of cementless cups with structural allografts and autografts, provided the graft supports less than 50% of the cup.

A meta-analysis of the orthopaedic literature was performed to evaluate the clinical performance of cementless, threaded acetabular cups. The hypothesis for the study was that the clinical performance of the cementless, threaded acetabular cup is equivalent to that of the cemented and porous-ingrowth acetabular cups. Ninety-five articles were included in the study. There were 1,269 cases in the threaded cup group, 1,979 in the porous control group, and 10,230 in the cemented control group. The primary outcome variable tested was the rate of aseptic loosening of the acetabular components as measured by the revision rates following the index total hip arthroplasty procedure. Other measures of acetabular component loosening that were analyzed included clinical rating scores, pain scores, frequency of radiolucencies according to location and size, frequency of radiolucencies as a separately defined outcome variable, progressive radiolucencies, and component migration. The threaded cup group was found to have a significantly higher rate of revision, clinical and pain score failures, progressive radiolucencies and migrations when compared with the cemented and porous control groups (P < .05). Despite the many limitations of meta-analyses and the poor state of the orthopaedic literature database, this study provides a reasonable comparison of the clinical performance of threaded acetabular cups with that of cemented and porous-ingrowth acetabular cups.

From 1980 through 1991 we screwed a preshaped cortico-cancellous bone graft onto the ileum wall to compensate acetabular deficiency in 94 consecutive total hip replacements. We report the results of 87 hips (79 patients) with an average follow-up of 30 months (12-75 months) postoperatively. Pain in dysplasia-coxarthrosis and congenital dislocation of the hip, destructive coxitis in rheumatoid arthritis and cup loosening was the main indication for surgery. According to the Merle d'Aubigné score the postoperative clinical evaluation demonstrated 77% very good and 18% good results. Due to component loosening the results had to be classified as unsatisfactory in 4 hips (2 cups and 2 stems). At the time of evaluation 90% of the arthroplasties was osseously consolidated as evidenced by trabecular bridging and structural integrity with host bone. Resorptions of the graft were noted in 32 hips. One cup was removed because of complete resorption and consecutive loosening, a further one was considered clinically and radiologically loose because of partial graft resorption. Two further complete resorptions and 28 partial lateral resorptions had no influence on the secondary stability of the implant. We are aware that these are short-term results. Nevertheless, we recommend the described method as a valuable addition to arthroplasties for acetabular rim defects both in osteoarthritis and in revision surgery.

Acetabuloplasty with solid autologous femoral head graft for the treatment of hip dysplasia is an established method which creates the contained cavity needed to accommodate the artificial cup. In order to evaluate the medium- and long-term results of this method using a cementless hemispheric cup, 34 patients (39 hips) operated on between 1979 and 1986 were clinically and radiologically reviewed. The minimal follow-up was 5 years (average 7.6 years). The Harris hip score increased from 36 points preoperatively to 89 points 1 year postoperatively and to 85.1 at the last follow-up. On roentgenographic evaluation, all grafts had been incorporated and appeared to have tolerated the mechanical loading well. Partial resorption of the graft occurred in 22 of the 39 hips, mainly in the lateral non-loaded zone. Twenty-nine of the 39 acetabular components showed migration, on average 4.2 mm cranially and 1.8 mm medially; 92% occurred during the first 2 years, and thereafter it was not progressive. Smaller cups migrated consistently more than larger cups. A significant correlation was found between cup migration and the degree of bone coverage of the cup, and extensive migration occurred in most cases with cup coverage by the host bone of less than 40%-50% of the weight-bearing surface of the cup. Only one acetabular component was altered significantly, and another appears to have become loose. The use of the normal-sized cups and cementless fixation medially in the primary acetabulum are thought to have contributed to our favorable mid- to long-term results.(ABSTRACT TRUNCATED AT 250 WORDS)

The purpose of this study was to determine the effects of superior displacement of the hip center and changes in three prosthetic parameters (neck length, neck-stem angle, and anteversion angle) on the capacity of muscles to generate force and moment about the hip. A three-dimensional model that calculates the maximum isometric forces and moments generated by 25 muscles crossing the hip over a wide range of body positions was used to evaluate the effects of a 2 cm elevation of the hip center and changes in the prosthetic parameters. After superior displacement of the hip center, the neck length was increased from 0 to 3 cm, the neck-stem angle was varied between 110 and 150 degrees, and the anteversion angle was varied between 0 and 40 degrees. Our analysis showed that a 2 cm superior displacement of the hip center would decrease the moment-generating capacity of the four muscle groups studied (abductors, adductors, flexors, and extensors) if neck length were not increased to compensate for decreased muscle length. In the computer model of an adult man that we used, a 2 cm increase in neck length restored the moment-generating capacity of the muscles by increasing muscle length and force-generating capacity. However, a 3 cm increase in neck length increased passive muscle forces substantially, which potentially could limit joint motion. An increased neck-stem angle (i.e. a valgus neck) decreased the abduction moment arm but increased the moment-generating capacity of the other muscle groups. A change in the anteversion angle from 0 to 40 degrees had a relatively small effect on the isometric moment-generating capacity of the muscles studied.

The authors present a consecutive series of 38 arthroplasties for osteoarthrosis secondary to hip dysplasia. All arthroplasties were performed by a single surgeon using Mittelmeier II (Autophor, Osteo AG, Selzach, Switzerland) ceramic cementless components. Crowe grades of subluxation were 60% grade I, 16% grade II, 12% grade III, and 12% grade IV. In all cases, the acetabular component was seated in the true acetabulum. The mean follow-up period was 75 months (range, 40-122 months). By the time of review, six hips (16%) had required revision for aseptic loosening, mainly of the femoral component. Good or excellent results were achieved in only 63% of the patients. In the group of surviving arthroplasties, the median Charnley hip scores before surgery were: pain, 2; movement, 3; and walking, 3. After surgery, the scores were: pain, 5; movement, 5; and walking, 6. All improvements were significant. The mean postoperative Harris hip score was 84. Poor scores were associated with contralateral hip disease (2 cases) and spina bifida (2 cases), significantly affecting function. The Autophor prosthesis can produce satisfactory results in some of these young patients with hip dysplasia. However, femoral loosening is a major problem and because of this, the authors have since changed to a newer stem design.

The use of bone-graft to augment the deficient acetabulum in primary and revision total hip arthroplasty (THA) is controversial. To identify factors affecting cup loosening in patients who received a bone-graft during THA, two orthopaedic surgeons retrospectively examined sequential radiographs. The surgeons also obtained independent computer measurements of hip center and cup abduction migration from preoperative, initial, and latest postoperative radiographs. Variables studied included host factors, graft factors, and technique factors. All conclusions were based on Kaplan-Meier log-rank analysis to account for differing lengths of follow-up periods among the cases. The authors report a series of 74 consecutive cases with a minimum 24-month follow-up period (mean, 40 months). All grafts appeared to unite. The clinicians found 80% stable cups, 8% possibly loose cups, and 12% (n = 9) definitely loose cups. In retrospect, technical errors were seen in six loose cups. Five revisions for loosening (6.7% of cases) were performed. Computer measurement found cup loosening in a higher percentage of cases than detected by the clinicians and did so an average of 18 months sooner. Acetabular cup loosening was associated with the American Academy of Orthopaedic Surgeons type III defects, use of allograft versus autograft, and initial cup abduction of 50 degrees or more. Kaplan-Meier survivorship analysis found 31% of cups radiographically loose and 15% revised at 5 years or more since surgery. Acetabular bone-grafting is technically demanding and should be employed when alternative reconstructions will not give a durable result.