Periacetabular Bone Loss Research Articles

The Measurement of the Oxidative Index of Polyethylene Obtained during Revision Hip Arthroplasty and Assessment of Its Variability Depending on the Degree of Osteolysis, Implantation Time, as Well as the Size and Material of the Utilized Head.

Background/Objectives: Aseptic loosening is the leading cause of late revision in total hip arthroplasty, primarily due to degenerative oxidation of polyethylene components, leading to wear particle formation and periacetabular osteolysis. This study aimed to analyze the oxidation levels in polyethylene liners and cemented cups retrieved from revision surgeries using Fourier-transform infrared spectroscopy (FTIR) and to explore the correlation between oxidation levels and factors such as head size, head material, fixation method, and implant survival time. Methods: Polyethylene liners and cups were analyzed post-revision surgery to assess oxidation levels, which were then compared to periacetabular bone loss measured by the Paprosky classification. This study evaluated the impact of head size (28 mm vs. 32 mm), head material (ceramic vs. metal), and fixation methods on oxidation. The relationship between the mean oxidation index (OI) and implant survival time was also investigated. Results: There was a significant positive correlation between the mean oxidation index of the polyethylene components and the severity of periacetabular osteolysis according to the Paprosky scale. While the mean OI for samples articulating with ceramic heads was lower than for those with metal heads, and the mean OI for samples with a 32 mm head size was lower than for those with a 28 mm size, these differences were not statistically significant. Furthermore, the fixation method did not affect the oxidation index, and no correlation was found between OI and the survival time of the implants. Conclusions: This study confirms a direct correlation between polyethylene oxidation and periacetabular osteolysis in hip replacements, highlighting the importance of material choice and design in potentially reducing the risk of aseptic loosening. Despite the lack of significant differences in oxidation levels based on head material and size, these factors may still play a role in the long-term outcome of hip arthroplasty, warranting further investigation.

Acetabular Revision with McMinn Cup: Development and Application of a Patient-Specific Targeting Device.

Surgeries of severe periacetabular bone defects (Paprosky ≥ 2B) are a major challenge in current practice. Although solutions are available for this serious clinical problem, they all have their disadvantages as well as their advantages. An alternative method of reconstructing such extensive defects was the use of a cup with a stem to solve these revision situations. As the instrumentation offered is typically designed for scenarios where a significant bone defect is not present, our unique technique has been developed for implantation in cases where reference points are missing. Our hypothesis was that a targeting device designed based on the CT scan of a patient's pelvis could facilitate the safe insertion of the guiding wire. Briefly, our surgical solution consists of a two-step operation. If periacetabular bone loss was found to be more significant during revision surgery, all implants were removed, and two titanium marker screws in the anterior iliac crest were percutaneously inserted. Next, by applying the metal artifact removal (MAR) algorithm, a CT scan of the pelvis was performed. Based on that, the dimensions and positioning of the cup to be inserted were determined, and a patient-specific 3D printed targeting device made of biocompatible material was created to safely insert the guidewire, which is essential to the implantation process. In this study, medical, engineering, and technical tasks related to the design, the surgical technique, and experiences from 17 surgical cases between February 2018 and July 2021 are reported. There were no surgical complications in any cases. The implant had to be removed due to septic reasons (independently from the technique) in a single case, consistent with the septic statistics for this type of surgery. There was not any perforation of the linea terminalis of the pelvis due to the guiding method. The wound healing of patients was uneventful, and the implant was fixed securely. Following rehabilitation, the joints were able to bear weight again. After one to four years of follow-up, the patient satisfaction level was high, and the gait function of the patients improved a lot in all cases. Our results show that CT-based virtual surgical planning and, based on it, the use of a patient-specific 3D printed aiming device is a reliable method for major hip surgeries with significant bone loss. This technique has also made it possible to perform these operations with minimal X-ray exposure.

20-year Results of a 3D Titanium Mesh Coating Stability of 31 Artificial Cups.

The aim of this work was to demonstrate the bony bond strength and resilience of a three-dimensional titanium mesh coating of an artificial acetabulum produced using the diffusion bonding technique. Under the extreme conditions ranging from abrasion-related osteolysis to acetabular perforation, the degree of residual bone and the integrity of the coating were determined. The remaining zones of the (still) stable bone connection are inevitably exposed to a greater load of the layer adhesion between the titanium mesh and the core shell. The investigation was intended to provide information about the stages of damage according to Paprosky in which it was still justifiable to leave the implant in place and simply change the inlay from the purely material-technical point of view of a stable coating. The bond between bone and implant was examined with regard to a possible retention of the implant for its adaptive remodeling up to 27 years. In a retrospective study, 31 explanted human acetabular cups of the Harris-Galante II type, with an average lifetime of 19.7 years (11-27 years), were examined by means of digital area measurement to determine both the bone areas remaining on the coating and the damaged areas of the titanium mesh. Periacetabular bone loss was recorded in a modified Paprosky (PAP) damage classification. Full hemispherical sections of 4 acetabular cups with a life time of 16, 20, 22 and 27 years were examined histopathologically using the diamond cut technique. The periacetabular bone loss resulted in damage class PAP I in 8 cases, PAP IIa in 7 cases, PAP IIb in 2 cases, PAP IIc in 9 cases, PAP IIIa in 3 cases and PAP IIIa in 2 cases PAP IIIb. The average amount of bone that was still firmly attached to the coating after explantation was 17% (0-70%) of the total cup surface. Paprosky I accounted for 44.1%, and PAP IIa and IIb stadiums together a total of 17.1%. The average bone fraction of the implants no longer anchored in the host bed at stages IIc, IIIa and IIIb was 2%. The average coating damage was 11% (0-100%) and was exclusively attributable to the unstable implants of stages IIc, IIIa and IIIb. The histopathological findings showed adaptive bone remodeling, that was detectable for up to 27 years through the titanium mesh down to the interface with the solid acetabular core. The titanium wire mesh was mostly surrounded by lamellar, mature bone. The results show that the connection between the Tivanium cup and the previously oldest and unchanged sintered coating - in the form of a three-dimensional titanium mesh applied in point and line contact - is very load-resistant even under the extreme loads of periacetabular osteolysis and cup perforations. Since there was no damage to the coating in periacetabular damage stages Paprosky I, IIa and IIb, it is justifiable in these damage stages to leave the implant in situ and to continue to use it with sole replacement of the inlay, but leaving the socket shell. The third-generation acetabular cup (Trilogy) with unchanged three-dimensional titanium mesh coating has been implanted in over 1.2 million cases for 26 years. After a long service life, an increasing number of wear and tear conditions can be expected in today's mostly elderly and vulnerable patient clientele. In view of the results presented here, the early detection of damage would make it possible to avoid costly and stressful explantation of the entire acetabular cup in favor of replacing the sole inlay in Paprosky stages I, IIa and IIb.

Use of custom-made acetabular components (CMAC) as part of atwo-stage procedure in patients with severe periacetabular bone loss

Implantation of custom-made acetabular components (CMAC) with load transmission onto the remaining bone stock and reconstruction of the "center of rotation" (COR) in cases of severe periacetabular bone defects. Severe periacetabular bone loss (Paprosky type IIIA/B) with or without pelvic discontinuity after septic or aseptic loosening with inadequate load capacity of the dorsal pillar and/or large supraacetabular defects. Acute or local infections, lack of compliance, taking into account the risks and complications: missing or limited expected postoperative functional gain, multimorbid patients with potential inoperability during the first and/or second intervention. Lateral transgluteal or posterolateral approach while protecting neurovascular and muscular structures. Preparation of the implant site based on preoperative planning with augmentation of bone defects as far as possible. Primarily stable anchoring with 2angle-stable pole screws in the ilium, an optional pole screw in the pubic bone for determination of COR, and stabilization screws in the iliac wing (optionally angle-stable). Use of dual mobility cup according to the soft tissue tension and intraoperative stability. For the first 6weeks postoperative partial weight-bearing (20 kg), followed by agradual increase of the load (10 kg per week). Between 2008 and 2018, 47patients with a Paprosky typeIII defect underwent implantation of amonoflanged CMAC. Main complication was aperiprosthetic joint infection with subsequent need for implant removal in9 of 10cases. Harris Hip Score improved from21.1 to 61.5points. X‑ray imaging displayed an angle of inclination of42.3 ± 5.3°, an anteversion of16.8 ± 6.2°, a∆ H of0.5 ± 0.2 mm and a∆ V of17.7 ± 1.1 mm according to Roessler etal.

An Isoelastic Monoblock Cup Retains More Acetabular and Femoral Bone Than a Modular Press-Fit Cup: A Prospective Randomized Controlled Trial.

For cup revision after total hip arthroplasty, sufficiently good periacetabular bone stock is a prerequisite for fixation of the revision implant. Cementless cups can lead to a relevant reduction of peri-implant bone mineral density (BMD) through stress-shielding. Fifty patients were included in this prospective randomized controlled trial. Group 1 (RM group) received an isoelastic monoblock cup (RM Pressfit vitamys; Mathys). Group 2 (IT group) received a modular titanium cup (Allofit-S IT Alloclassic with a polyethylene liner; Zimmer). Periacetabular BMD was determined and subdivided into 4 regions of interest by dual x-ray absorptiometry at 1 week (baseline) and at 4 years postoperatively. Our primary outcome was reduction in periacetabular BMD. Periacetabular BMD was reduced by an average of 15.1% in the RM group and 16.5% in the IT group at 4 years postoperatively. No significant difference was found between the 2 groups over the periacetabular structure as a whole. However, the decrease of BMD in the polar region was significantly different in the RM group (4.9% ± 10.0%) compared with the IT group (15.9% ± 14.9%, p = 0.005). Use of the isoelastic RM cup showed significantly less bone loss than the modular IT cup. Relevant loss of BMD at 4 years after surgery was identified in the periacetabular region in both groups. No differences between the 2 cup systems were found when looking at the overall periacetabular region. As a secondary outcome, less postoperative periacetabular bone loss occurred in the polar region when an isoelastic cup was used. Longer follow-up is required to allow for conclusions to be drawn about the long-term course of the 2 cup systems. Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Novel Acetabular Hemiarthroplasty for Palliation of Periacetabular Metastatic Disease With Articular Bone Loss

Introduction: Periacetabular metastatic disease is often successfully treated nonoperatively. Cases with extensive bone loss and the subchondral collapse of the acetabular dome require reconstruction to restore mobility. These procedures are associated with significant morbidity and postoperative complications. Objectives: The primary objective of this case study is to describe a novel “acetabular hemiarthroplasty” to manage the periacetabular metastatic disease with subchondral collapse and protrusio. Materials and Methods: Five consecutive patients with significant periacetabular bone loss and subchondral collapse were surgically managed with a novel acetabular hemiarthroplasty. The hospital records were retrospectively reviewed and outcomes at the most recent follow-up are reported. Results: Our findings suggest that acetabular hemiarthroplasty could be a valuable option for surgical palliation of periacetabular metastatic disease involving subchondral collapse and protrusio. Conclusion: This technique provides for the restoration of joint mechanics and weight bearing without the need for total hip arthroplasty. Compared with complex hip arthroplasty, the authors believe this novel acetabular hemiarthroplasty potentially reduces operative time and blood loss while substantially limiting the risk of dislocation.

Acetabular reconstruction for primary and revision total hip arthroplasty using Kerboull-type acetabular reinforcement devices-case-control study with factors related to poor outcomes of surgery.

Kerboull-type acetabular support rings (KT) and allogenic bone graft were used for severe periacetabular bone loss with primary and revision total hip arthroplasty (THA). The purpose of this case–control study is to evaluate the risk factors related to poor outcomes of surgery.Sixty patients underwent primary THA and revision THA using allogenic bone graft with KT for large acetabular deficiency. These patients were retrospectively evaluated postoperatively and followed-up by radiograph. The minimum follow-up period was 4 years and averaged 7 years. A radiological failure was defined by the following criteria:1)substantial migration defined as change in the angle of inclination of more than 5 degrees or migration of more than 5 mm,2)breakage of the screw or device,3)acetabular revision due to aseptic loosening.Expected risk factors were defined as female, age >75 years, body mass index (BMI) >25%, medical history of hypertension, renal failure, liver steatosis, diabetes, hyperlipidemia, cardiac infarction, smoking, American Academy of Orthopedic Surgery (AAOS) classification III or IV, bleeding>500 mL, time of surgery >3hours, high hip center-type KT, inclination of KT >45 degrees, screw angle >25 degrees, morselized bone graft, Kawanabe's classification stage 3 or 4 and revision surgery. Nineteen hips (31.6%) revealed radiological failure according to our criteria, and revision THA was performed in 2 hips (3.3%). In the statistical analysis, morselized bone graft and high hip center-type KT were identified as factors of poor outcomes of surgery.

Revision arthroplasty of the hip : Direct anterior approach

The direct anterior approach to the hip allows good exposure of acetabulum and periacetabular bones. For simple acetabular revisions it can be chosen to be small (minimally invasive); in the case of extensive periacetabular bone loss exposure of the entire ilium cranial of the acetabulum may be achieved, and the pubic bone as well as inner-pelvic structures adjacent to the acetabulum can be exposed. The internerval plane of the approach between muscles innervated by the femoral nerve and the gluteal nerves allows exposure of the ilium without endangering the nerve supply of gluteal muscles.

The use of customized cages in revision total hip arthroplasty for Paprosky type III acetabular bone defects.

Revision total hip arthroplasty (THA) is challenging if severe periacetabular bone loss is present. Here we describe a method that uses a customised cage to reconstruct an acetabulum with a massive bone defect. Designed with the aid of the rapid prototyping technique, a customised cage with a hook, crest and flange or braids was made, and then utilized to reconstruct severe compromised acetabulum in revision THA since 2001. Twenty-two patients (23 hips) were included in this study. The mean patient age at the time of surgery was 60.9 years (range, 38-80 years). Three hips had massive acetabular bone defects of Paprosky type IIIA and 20 of type IIIB. The Harris hip score was used to evaluate hip function. Radiographs were taken to evaluate loosening of the cage and resorption of allograft bone. The average follow up was 81.6 ± 24.9 months. The mean Harris hip score improved from 39.6 pre-operatively to 80.9 at the final follow-up. There were no instances of deep infection, severe venous thrombosis, and nerve palsy. One patient who had an intra-operative rupture of the superior acetabular artery was successfully treated using the haemostatic suturing technique. Two patients experienced dislocation at post-operative days four and six, respectively, and both were treated with closed reduction and skin traction for three weeks. The present study demonstrates that a customised cage may be a promising option for THA revision of severely compromised acetabula. Extended follow-up is necessary to evaluate the long-term performance of this approach.

Management of severe periacetabular bone loss combined with pelvic discontinuity in revision hip arthroplasty.

Revision of failed total hip arthroplasty with massive acetabular bone loss resulting in pelvic discontinuity represents a rare but challenging problem. The objective of this study was to present short to mid-term results of revision total hip arthroplasty with a custom-made acetabular implant in a consecutive series of patients with pelvic discontinuity. We retrospectively reviewed 18 consecutive patients with massive acetabular bone loss (Paprosky Type 3B) resulting in pelvic discontinuity reconstructed with revision total hip arthroplasty using a custom-made acetabular component. The prosthesis was created on the basis of a thin-cut 1-mm computed tomography (CT) scan of the pelvis. Initial stability of the implant was obtained by screw fixation. Harris hip score and sequential radiographs were used to evaluate the clinical and radiographic results. At an average follow up of 30 months (range 17-62 months) 16 of 18 (88.9%) custom-made implants were considered radiographically stable without signs of acetabular migration of more than 2 mm in the horizontal or vertical direction, implant rotation or screw breakage. Complications included two periprosthetic joint infections treated with explantation of the implant. Three patients had recurrent dislocations postoperatively. The mean Harris hip score improved from 28 ± 12 points preoperatively to 69 ± 13 points at the time of last follow up. Treatment of acetabular bone loss and pelvic discontinuity with a custom-made acetabular component can provide a durable solution with good clinical and radiographic results.

Classifications In Brief: Paprosky Classification of Acetabular Bone Loss

Classifications In Brief: Paprosky Classification of Acetabular Bone Loss

Short-term Results of a Custom Triflange Acetabular Component for Massive Acetabular Bone Loss in Revision THA

Managing severe periacetabular bone loss during revision total hip arthroplasty (THA) is a challenging task. Multiple treatment options have been described. A custom triflanged acetabular component is a recent treatment option. The authors retrospectively reviewed 19 hips in 19 patients with massive periacetabular bone loss (Paprosky types 3A/3B and AAOS types III/IV) treated with custom triflanged acetabular components. Mean patient age at surgery was 58 years (range, 42-79 years).At an average follow-up of 31 months (range, 16-59 months), mean Harris Hip Score had improved from 38 preoperatively to 63 postoperatively, and mean Western Ontario McMaster Osteoarthritis Index scores had improved from 43 preoperatively to 26 postoperatively. Sixty-five percent of cases were considered successful. Three (16%) patients had significant complications; 2 (11%) custom triflanged acetabular components were removed due to failure. At last follow-up, 6 (43%) of 14 patients reported that their ambulatory status was improved vs their preoperative status, 3 (21%) reported no change, and 5 (36%) reported that their ambulatory status was worse than their preoperative status.In this study, the use of a custom triflanged acetabular component for massive periacetabular bone loss in revision THA had less favorable results than in other reports. Use of a custom triflanged acetabular component for massive periacetabular bone loss in revision THA remains a viable option, but surgeon and patient expectations should be realistic.

How to Do a Revision Total Hip Arthroplasty: Revision of the Acetabulum

The need for revision total hip arthroplasty continues to increase as the indications for total hip replacement broaden and the average life expectancy of patients and their demands for activity increase. To achieve a successful long-term outcome after revision acetabular surgery, the surgical reconstruction must provide a mechanically stable construct that will minimize micromotion, allow bone ingrowth, and restore appropriate hip biomechanics. Achieving these goals during revision acetabular surgery can be challenging because of periacetabular bone loss and a compromised biologic environment. Acetabular classifications can help to preoperatively predict areas of bone loss to guide treatment options. Most acetabular defects can be managed with a hemispheric or elliptic porous acetabular component; however, large areas of segmental or cavitary bone loss may require alternative treatments such as custom implants, metal/allograft augmentation, or an acetabular cage reconstruction.

Management of Periacetabular Bone Loss in Revision Hip Arthroplasty

The goals of acetabular revision surgery are to restore the anatomy and achieve stable fixation for the new acetabular component. The existing bone stock and the type of defect are determining factors in the surgical decision making. When necessary, and especially in younger patients, attempts should be made to restore the bone stock by grafting. The advent of modern reconstruction options, like the trabecular metal revision system and the cup-cage construct, provide more options in addressing the management of severe defects. Trabecular metal has a porosity similar to bone and provides an environment more favorable to bone graft remodeling than conventional metals. We present an overview of our experience and current approach to acetabular revision. In addition, we report our preliminary results with trabecular metal cups and trabecular metal cup-cage constructs used in conjunction with bone graft for addressing major bone defects.

Magnetic resonance imaging in the evaluation of periprosthetic acetabular osteolysis: A cadaveric study

Periprosthetic osteolysis is a well recognized complication of total hip arthroplasty that leads to implant failure. The ability to accurately assess and visualize the position and volume of periacetabular bone defects is paramount for clinical observation and medical treatment, as well as pre-operative planning of revision surgery. We have developed a modified magnetic resonance imaging (MRI) protocol that is useful in detection and quantification of periacetabular bone loss. The purpose of this study is to compare MRI to plain film analysis in the assessment of periacetabular bone loss using a cadaver model. MRI was 95% sensitive in the detection of lesions. Specificity was 98%, and accuracy was 96%. Lesion detection was not statistically dependent on lesion location ( p = 0.27). The mean absolute error in determining lesion size was 0.8 ± 2.2 cm 3. There was a correlation between increasing lesion size and lesion detection ( p = 0.02, logistic regression). The largest lesion that was missed by MRI analysis measured 2.8 cm 3, and all lesions ⩾3.0 cm 3 were correctly identified, with a relative error volume measurement of 12.4 ± 25.3%. This correlated to an absolute error of 1.4 ± 2.4 cm 3. Using conventional radiographic analysis, the overall sensitivity of lesion detection was 52%, and the specificity was 96%. Using plain film analysis, identification of true lesions depended on the location with 83% of ilial lesions, 64% of pubic lesions, 55% of ischial lesions, and 0% of posterior wall lesions correctly identified. The modified MRI technique utilized did allow for accurate visualization of simulated osteolytic lesions, and may provide a suitable noninvasive method to provide serial assessment of clinical periacetabular osteolysis without the use of ionizing radiation.

Use of Custom Triflanged Acetabular Components in Revision Total Hip Arthroplasty

Difficulty persists in consistently treating massive acetabular defects in revision total hip arthroplasty. A relatively new treatment option for these complex cases is a custom triflanged acetabular component created from anatomic data derived from a computed tomography scan of the pelvis. The custom triflanged acetabular component achieves fixation on the remaining ilium, ischium, and pubis with multiple fixation screws while the acetabular defect is filled with cancellous allograft bone. A retrospective review was done of 26 hips (26 patients) with massive periacetabular bone loss (Paprosky Type 3B) reconstructed with a custom triflanged acetabular component. Twenty-three of 26 patients (88.5%) were considered clinically successful at short-term followup (average, 54 months; range, 24 to 85 months), with stable fixation and reconstruction of periacetabular bone. Three failures occurred from loss of ischial fixation in two patients with a preoperative pelvic discontinuity and one patient with severe osteopenia. These devices should be used with caution in patients with a preoperative pelvic discontinuity unless additional column plating is done.

Limits in cementless hip revision total hip arthroplasty. Midterm experience with an oblong revision cup

Revision of an acetabular component in a patient who has severe periacetabular bone loss is a complex problem, particularly when there is not enough bone stock to allow placement of an acetabular component near the normal anatomical hip center. To fill the defect, a valuable option for revision arthroplasty is the cementless oblong revision cup (LOR). 50 consecutive revisions of the acetabular component were performed in 48 patients. The mean age at the time of revision was sixty-one years (range, thirty-three to seventy-eight years). Forty-eight hips were available for follow-up, at a mean of thirty-two months (range, eighteen to sixty-one months). The acetabular defect classified according to Paprosky, the migration and the radiolucencies were followed radiologically. 8 hips (16 %) were revised again: two because of infection (4 %) and six because of instability (12 %). The revised hips are not associated to the preoperative degree of acetabular defect (34 % defect type III) (P > 0.05). The mean Harris Hip score was corrected from 36.5 (range, 7.5 to 92.5) to 78.2 points (range, 47.6 to 97.6) (P < 0.01). The mean d'Aubigné Score was corrected from 8.3 (range, 4 to 6) to 15 points (range, 10 to 18) (P < 0.01). Neither pre- nor postoperative results were associated to the degree of acetabular defect (P > 0.05). However, patients with multiple revisions had a significantly reduced clinical outcome than patients with the first revision (P < 0.05). The hip center of rotation, cranially placed to the contralateral side (0.92 cm) was corrected by the revision to a more normal anatomic rotation center (0.27 cm). Partial zonal radiolucencies, always smaller than 1.5 mm were seen in 30 % of the patients. The mean migration of the acetabular component was not significant (P > 0.05). The authors support the use of the cementless oblong revision cup if contact can be made with host bone to more than 50 %. If this is not possible, acetabular bone reconstruction combined with a roof ring and a cemented cup is the component of choice.

Management of massive acetabular defects in revision total hip arthroplasty

Twenty-four cases of massive periacetabular bone loss (Paprosky Type 3B) were reconstructed using custom triflanged acetabular components (CTAC). Fixation is obtained by the creation of a triflanged component that is anchored to the ilium, ishium, and pubis with multiple fixation screws. Acetabular defects are grafted with large amounts of cancellous allograft. Modular polyethylene liners are then locked into the CTAC. Twenty-one of 24 cases (87.5%) were considered clinically successful at short-term follow-up (average, 48 months; maximum, 78 months), with stable fixation and reconstruction of periacetabular bone. Three failures occurred from loss of fixation in patients with a preoperative dissociation of the hemipelvis and severe osteopenia. Presently, these devices should be used with caution in cases with a preoperative dissociation of the hemipelvis, unless additional column plating is performed. © 2003 Elsevier Inc. All rights reserved.

High placement of an acetabular component inserted without cement in a revision total hip arthroplasty. Results after a mean of ten years.

Revision of an acetabular component in a patient who has severe periacetabular bone loss is a complex problem, particularly when there is not enough bone stock to allow placement of an acetabular component near the normal anatomical hip center. A valuable option for revision in such a situation is placement of a hemispherical shell, fixed with screws and without cement, against the superior margin of the acetabular defect. The resulting hip center is more proximal than that seen following a typical primary total hip replacement. Forty-six hips in forty-four patients were treated consecutively, between July 1984 and February 1988, with a revision in which a hemispherical acetabular component was fixed with screws and without cement. All shells but one were placed with a so-called line-to-line fit. The procedures resulted in a so-called high hip center--that is, the center of rotation of the revised hip was located at least thirty-five millimeters proximal to the interteardrop line. The mean age of the patients at the time of the index procedure was fifty-two years (range, twenty-five to eighty-one years). The most common diagnosis for which the original arthroplasty was performed was osteoarthritis secondary to congenital hip dysplasia or dislocation (twenty-two hips). Thirty-four hips had had a high hip center before the index revision, and most patients had had a substantial limb-length discrepancy, with a mean of 1.6 centimeters of shortening on the side of the operation. In thirty-three hips, the femoral component was replaced as well, with a long-neck or calcar-replacement stem used when necessary to maintain or increase the length of the limb. Six patients (six hips) died before the minimum eight-year follow-up interval; none had had another revision or loosening of the revised acetabular component. Of the remaining patients, four (four hips) had the implant removed. One of them had a resection arthroplasty and one of them had a hip disarticulation because of infection after a subsequent femoral reoperation. Another had a hip disarticulation because of late infection. The fourth implant was removed because it had displaced into the pelvis at approximately six years; this was the only reoperation for aseptic loosening in the series. The remaining thirty-six hips (thirty-four patients) were followed for a mean of 10.4 years (range, 8.5 to 12.7 years). One acetabular component migrated medially and was scheduled for revision. No other acetabular component was loose or had been revised. The mean Harris hip score was 81 points (range, 56 to 100 points) at the time of the most recent follow-up. Despite the use of a high hip center, the prevalence of a positive Trendelenburg sign was reduced from 98 percent (forty-five of forty-six hips) preoperatively to 44 percent (sixteen of thirty-six hips) at the time of the most recent follow-up. The short limbs were lengthened a mean of seven millimeters (range, five millimeters of shortening to forty millimeters of lengthening). In this study of acetabular revisions with use of a high hip center in patients who had major periacetabular bone loss, mechanical failure occurred in 4 percent (two) of the forty-six hips in the entire series and in 6 percent (two) of the thirty-six hips in patients who were alive and still had the implant in place after a mean of 10.4 years of follow-up. The use of a high hip center did not adversely affect function of the abductor muscles, and the mean limb-length discrepancy was reduced by the femoral reconstruction.

Bipolar Components for Severe Periacetabular Bone Loss Around the Failed Total Hip Arthroplasty

Twenty-seven patients had revision of a failed total hip arthroplasty using a bipolar component to replace the acetabulum. The procedure was done when periacetabular bone loss precluded stable fixation of the revision component to bone. In addition, three of the operations were done for recurrent dislocation in patients with severe medical problems. Significant component migration occurred in one case, and one patient required reoperation for dislocation in the early postoperative period. Functional results in these 27 patients were quite satisfactory; bone grafts reliably became consolidated to the host pelvis.