Jumbo cups for revision of acetabular defects after total hip arthroplasty: a retrospective review of a case series

Clinical and radiological outcomes of jumbo cup in revision total hip arthroplasty: A systematic review

Introduction

Many studies have reported the clinical outcomes of a jumbo cup in revision total hip arthroplasty (rTHA) with acetabular bone defect. We conducted a systematic review to access the survivorship and clinical and radiological outcomes of a jumbo cup in rTHA.

Methods

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive literature search from PubMed, MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews was performed with the keywords (“revision” OR “revision surgery” OR “revision arthroplasty”) AND (“total hip arthroplasty” OR “total hip replacement” OR “THA” OR “THR”) AND (“jumbo cup” OR “jumbo component” OR “extra-large cup” OR “extra-large component”). Studies reporting the clinical or radiological outcomes were included. The basic information and radiological and clinical results of these studies were extracted and summarized for analysis.

Results

A total of 19 articles were included in the systematic review. The analysis of clinical results included 953 hips in 14 studies. The re-revision-free survivorship of the jumbo cup was 95.0% at a mean follow-up of 9.3 years. Dislocation, aseptic loosening, and periprosthetic joint infection were the top three complications with an incidence of 5.9%, 3.0%, and 2.1%, respectively. The postrevision hip center was relatively elevated 10.3 mm on average; the mean postoperative leg-length discrepancy was 5.4 mm.

Conclusion

A jumbo cup is a favorable option for acetabular bone defect reconstruction in rTHA with satisfying survivorship and acceptable complication rates.

New acetabulum bone formation after 10-years impaction bone graft and cemented acetabular cup lead to simple revision-THA with cementless acetabular cup: A case report

BACKGROUND

Secondary hip osteoarthritis with acetabular bone defect is still a challenging case in hip arthroplasty surgery. The incidence of revision total hip arthroplasty is estimated to be between 10% and 15% in 10 years. Simple revision cementless acetabular cup after a prior complex cemented-THA rarely performed.

CASE PRESENTATION

A case of aseptic loosening with prosthesis dislocation after THA was reported in a 54 year-old female patient. The patient had prior surgery of THA 10 years ago due to secondary post-traumatic hip osteoarthritis with acetabular bone defect. At the first surgery, cemented acetabular cup with acetabular bone grafting was performed to fill the defect. A complete new acetabulum bone formation was encountered at 10 years after the surgery which lead to simple revision THA with primary cementless acetabular cup. Excellent functional outcome was also reported at the final follow-up after revision THA.

CONCLUSION

This case showed that the potential of bone healing of the acetabulum cannot be underestimated. Therefore, it is suggested to always put an adequate bone graft to manage acetabular bone defect in THA surgery and a new acetabulum bone formation can be expected.

Cementless jumbo cups for revision of failed Furlong prosthesis. A case series

BACKGROUND

Revision of failed total hip arthroplasty (THA) presents great challenge to any orthopaedic surgeon especially in the presence of acetabular defects where the main goal is to achieve durable fixation of prosthetic components to bone which is the key to successful revision surgery.

METHODS

Seventeen patients (17 hips) with mean age of 52 (40-61) years had revision surgery for aseptic failure of Furlong hydroxyapatite-ceramic-coated (HAC) prosthesis using cementless jumbo cups. Patients were reviewed clinically and radiographically with mean follow-up of 3.5 years (2-6). No patient was lost to follow up.

RESULTS

All revised acetabular components showed polyethylene wear, severe metallosis, with acetabular defects IIB (4/17), and IIIA (13/17) according to Paprosky classification. The femoral component was well fixed in all cases but one patient had stem revision for femoral fracture mal-union. There was one early post-operative infection; there was no postoperative dislocation, sciatic nerve injury, periprosthetic fracture or deep venous thrombosis. At last follow-up, no progressive radiolucencies or acetabular migration was identified. The mean Harris hip score improved from 42 (24-59) pre-operatively to 85 (72-92).

CONCLUSION

Good clinical results and radiographic stability were obtained at short term follow up after acetabular revision using cementless jumbo cups, which justify its use in revision surgery even in the face of major acetabular defects. Furlong HAC femoral component gives excellent long-term survival in young and active patients with a survival rate of 94% at 18.6 years.

Acetabular revision arthroplasty using press-fitted jumbo cups: an average 10-year follow-up study

INTRODUCTION

Acetabular revision arthroplasty using jumbo cups for moderate-to-severe acetabular defects has varied outcomes. We evaluated the clinical and radiological outcomes of acetabular revision arthroplasty using a press-fitted jumbo cup and sought to identify factors that influence outcomes during intermediate follow-up.

MATERIALS AND METHODS

Eighty patients (47 men, 33 women; 80 hips) who underwent acetabular revision arthroplasty using press-fitted jumbo cups were included. The mean follow-up period was 10.4 years. Harris hip score (HHS), presence of groin pain, radiographic results, and Kaplan-Meier survival curves were evaluated. Implant design and surgery-related and patient-related factors were assessed to identify influential factors for cup loosening. Migration and wear analyses were performed using Einzel-Bild-Röntgen-Analyse software.

RESULTS

The mean preoperative HHS of 53 had improved to 77 at the final follow-up (p = 0.005). Nine patients experienced groin pain. Acetabular cup loosening was observed in seven cups (8.7%), and one jumbo cup was replaced with a reinforcement cage. The survival rate of the acetabular cup was 91% at 16 years according to the Kaplan-Meier analysis. Osteolysis was identified around the cup in six cases (7.5%). Acetabular cup loosening occurred more frequently in patients with conventional polyethylene liners than in those with highly cross-linked polyethylene liners (p = 0.045). The mean total migration was 1.52 mm, and the mean total wear was 0.98 mm. There was a positive correlation between total migration and total wear (p = 0.023; Spearman's rho = 0.388). The mean wear rate of the patients with the cup inclination angle < 50° was significantly lower than those with the cup inclination angle > 50° (p = 0.001). There were four cases of complications (three dislocations and one infection) that did not require revision surgery.

CONCLUSION

Press-fitted jumbo cups for acetabular revision arthroplasty exhibited encouraging results during follow-up for an average of 10 years. Use of highly cross-linked polyethylene liners and proper placement of the acetabular component with an inclination angle < 50° may contribute to better clinical outcomes after acetabular revision arthroplasty with jumbo cups.

Reconstruction of failed acetabular component in the presence of severe acetabular bone loss: a systematic review

Acetabular revision especially in the presence of severe bone loss is challenging. There is a paucity of literature critiquing contemporary techniques of revision acetabular reconstruction and their outcomes. The purpose of this study was to systematically review the literature and to report clinical outcomes and survival of contemporary acetabular revision arthroplasty techniques (tantalum metal shells, uncemented revision jumbo shells, reinforced cages and rings, oblong shells and custom-made triflange constructs). Full-text papers and those with an abstract in English published from January 2001 to January 2016 were identified through international databases. A total of 50 papers of level IV scientific evidence, comprising 2811 hips in total, fulfilled the inclusion criteria and were included. Overall, patients had improved outcomes irrespective of the technique of reconstruction as documented by postoperative hip scores. Our pooled analysis suggests that oblong cups components had a lower failure rate compared with other different materials considered in this review. Custom-made triflange cups had one of highest failure rates. However, this may reflect the complexity of revisions and severity of bone loss. The most common postoperative complication reported in all groups was dislocation. This review confirms successful acetabular reconstructions using diverse techniques depending on the type of bone loss and highlights key features and outcomes of different techniques. In particular, oblong cups and tantalum shells have successful survivorship.

The Utilization of Metal Augments Allows Better Biomechanical Reconstruction of the Hip in Revision Total Hip Arthroplasty With Severe Acetabular Defects: A Comparative Study

BACKGROUND

Reconstructing the normal hip biomechanics is important for a successful revision total hip arthroplasty (THA). Little is known about whether using metal augments in revision THA is biomechanically superior to traditional techniques.

METHODS

A retrospective review was conducted on 74 consecutive THAs revised using metal augments with a cementless hemispherical cup and 77 consecutive THAs revised using the jumbo cup, all with a minimum 2-year follow-up. Biomechanical parameters were measured before and immediately after the revision. Radiological and clinical outcomes at follow-ups were also evaluated.

RESULTS

The metal augment group had a reconstructed center of rotation (COR) that was 6.5 mm closer to the anatomic COR in height (P < .001), had 3.6 m smaller cup size (P < .001), and had 5.7 mm less head-cup difference (P < .001). Moreover, there was a reconstructed COR that was much closer to the anatomic COR (vertical distance: 1.8 vs 14.1 mm, P < .001; horizontal distance: -2.1 vs 7.9 mm, P = .013), had 4.1 mm greater femoral offset (P = .006), and had 8 mm less leg length discrepancy (P = .035) in the subgroup of Paprosky type III bone defects when compared to the jumbo cup group. All cup-augment constructs were radiologically stable with a higher mean postoperative Harris Hip Score (P = .012). One jumbo cup was radiologically unstable.

CONCLUSION

In revision THA, utilizing metal augments helps to restore the COR position more precisely, avoid using a larger cup, reduce head-cup difference, rebuild femoral offset, and decrease leg length discrepancy, particularly with Paprosky type III bone defects. Moreover, it provides satisfactory radiological and clinical outcomes in the short term.

Structural and Morselized Allografting Combined with a Cementless Cup for Acetabular Defects in Revision Total Hip Arthroplasty: A 4- to 14-Year Follow-Up

Using morselized and structural allograft to restore bone stock for massive acetabular bone defect in revision total hip arthroplasty (THA) is an appealing procedure. However, concerns about inability to achieve long-term stability following allograft resorption remained. From 2003 to 2012, 59 hips in 58 patients undergoing revision THA for Paprosky type II or III acetabular defects were retrospectively reviewed. The acetabular defects were managed with deep-frozen morselized and structural allografts, and a press-fit cementless cup along with supplementary screws. Clinical outcomes and radiographic results were analyzed with a mean follow-up of 8.7 years. The clinical successful rate was 100% for hips with Paprosky type II defect, 95.2% for IIIA defect, and 92.8% for IIIB defect. Three hips with type III defect failed at 4, 7, and 9 years, respectively. Harris Hip Score improved significantly from 60.1 preoperatively to 91.3 at the latest follow-up. All hips with good clinical results showed trabecular bridging in the allograft-host bone interface. Deep-frozen structural and morselized allograft in combination with a press-fit cementless cup represented a viable option to reconstruct acetabular defects in revision THA.

Acetabular Revision Arthroplasty Using an Uncemented Deep Profile Jumbo Component: A Ten to Sixteen Year Follow-Up Study

BACKGROUND

The purpose of this study is to evaluate the outcome of revision total hip arthroplasty using an uncemented deep profile jumbo acetabular component in patients who had been followed for a minimum of 10 years postoperatively.

METHODS

Between 1997 and 2001, 61 revision total hip arthroplasties were performed in 58 patients, with use of the +5 Deep Profile acetabular shell. The outcome with regard to retention vs re-revision of the acetabular component was determined for every hip. At a mean of 13 years (range 10-16) postoperatively, 30 patients (32 hips) were living. The Harris hip score, radiographic results, complications, and Kaplan-Meier survivorship were evaluated.

RESULTS

In the entire cohort of 61 hips, 4 acetabular components have been re-revised. Two shells were re-revised for sepsis: 1 shell was re-revised for aseptic loosening and 1 for recurrent dislocation. In the 32 hips followed for a minimum of 10 years postoperatively, 2 cups have been re-revised: 1 for aseptic loosening and 1 for recurrent dislocation. One additional shell was loose by radiographic criteria. With failure defined as re-revision for any reason, implant survival (95% confidence interval) was 92.6% (81.0-97.2) at 16 years. With failure defined as re-revision for aseptic loosening, implant survival was 97.4% (82.8-99.6) at 16 years.

CONCLUSION

Revision total hip arthroplasty with the +5 Deep Profile acetabular component was associated with a good rate of survival at 16 years.

Excellent long-term results of the Müller acetabular reinforcement ring in primary cup revision

Background and purpose - The original Müller acetabular reinforcement ring (ARR) was developed to be used for acetabular revisions with small cavitary and/or segmental defects or poor acetabular bone quality. Long-term data for this device are scarce. We therefore investigated long-term survival and radiographic outcome for revision total hip arthroplasty using the ARR. Patients and methods - Between October 1984 and December 2005, 259 primary acetabular revisions using an ARR were performed in 245 patients (259 hips). The mean follow-up time was 10 (0-27) years; 8 hips were lost to follow-up. The cumulative incidence for revision was calculated using a competing risk model. Radiographic assessment was performed for 90 hips with minimum 10 years' follow-up. It included evaluation of osteolysis, migration and loosening. Results - 16 ARRs were re-revised: 8 for aseptic loosening, 6 for infection, 1 for suspected infection, and 1 due to malpositioning of the cup. The cumulative re-revision rate for aseptic loosening of the ARR at 20 years was 3.7% (95% CI 1.7-6.8%). Assuming all patients lost to follow-up were revised for aseptic loosening, the re-revision rate at 20 years was 6.9% (95% CI 4.1-11%). The overall re-revision rate of the ARR for any reason at 20 years was 7.0% (95% CI 4.1-11%). 21 (23%) of the 90 radiographically examined ARR had radiographic changes: 12 showed isolated signs of osteolysis but were not loose; 9 were determined loose on follow-up, of which 5 were revised. Interpretation - Our data suggest that the long-term survival and radiographic results of the ARR in primary acetabular revision are excellent.

Comparative Study of Peripheral Rim Fixation Using Jumbo Cup in Revisional Hip Arthroplasty

Purpose

It is challenging procedure to revise acetabular component in acetabulum with severe bone defect or deformity. The jumbo cup is good option for revisional arthroplasty in large bone defect. The purpose of this study is to compare the prognosis of revisional total hip arthroplasty using jumbo cup with peripheral rim fixation and no rim fixation.

Materials and Methods

We included the patients who had performed acetabular revisional total hip arthroplasty from January 2002 to March 2015 in our institute. Total of 51 hips (51 patients) were included. The mean follow up period was 51 months (range, 12 to 154 months) and mean age was 60.7 years (range, 30 to 81 years). We divided into two groups (peripheral rim fixation group and no rim fixation group) by anteroposterior and lateral plain radiograph. We compared survival rate, hip center change and clinical outcomes between two groups.

Results

There were 37 patients in peripheral rim fixation group and 14 patients in no rim fixation group. There was one patient who had aseptic loosening necessary to re-revision in rim fixation group and 3 patients in no rim fixation group. And one patient had superficial infection in rim fixation group and one patient had periprosthetic fracture in no rim fixation group. Survival rate was higher in the peripheral rim fixation group (97.3%) than no rim fixation group (78.6%, P=0.028)

Conclusion

Based on our findings, peripheral rim fixation might be recommended to improve short-term outcome after revision total hip arthroplasty using jumbo cup.

A 2- to 7-Year Follow-Up of a Modular Iliac Screw Cup in Major Acetabular Defects: Clinical, Radiographic and Survivorship Analysis With Comparison to the Literature

BACKGROUND

Inadequate acetabular bone stock is a major issue in total hip arthroplasty, and several treatment options are available. Stemmed cups have been used in this scenario with variable results. A novel modular polyaxial uncemented iliac screw cup (HERM-BS-Sansone cup-Citieffe s.r.l., Calderara di Reno, Bologna, Italy) has been recently introduced to overcome the drawbacks of stemmed cups. In this retrospective study, we report the results of this cup in patients with large acetabular bone defects at 2- to 7-year follow-up.

METHODS

We evaluated a consecutive series of 121 hips (118 revisions and 3 complex primary arthroplasties) treated with this novel cup at a mean follow-up of 46 months. Kaplan-Meier survival analysis was performed with implant revision for any reason as a primary end point. Further survival analysis was performed excluding septic failures. Clinical outcome was assessed with the Harris Hip Score.

RESULTS

There had been 7 reoperations: 1 for aseptic loosening, 5 for deep infection, and 1 for recurrent dislocation. In 5 cases, the cup was removed; estimated survival rate at 5-year follow-up with implant removal for any reason was 95.6% (95% confidence interval = 91-99), and 98.3% (95% CI = 96-100) excluding those failed for infection. Mean Harris Hip Score at latest follow-up was 77 points (range, 44-95; standard deviation = 11.9).

CONCLUSION

The present findings show the short-term efficacy of the iliac screw cup with respect to implant survival. A longer follow-up and a larger number of patients are necessary to confirm the encouraging preliminary results.

The jumbo acetabular component for acetabular revision

The ‘jumbo’ acetabular component is now commonly used in acetabular revision surgery where there is extensive bone loss. It offers high surface contact, permits weight bearing over a large area of the pelvis, the need for bone grafting is reduced and it is usually possible to restore centre of rotation of the hip. Disadvantages of its use include a technique in which bone structure may not be restored, a risk of excessive posterior bone loss during reaming, an obligation to employ screw fixation, limited bone ingrowth with late failure and high hip centre, leading to increased risk of dislocation. Contraindications include unaddressed pelvic dissociation, inability to implant the component with a rim fit, and an inability to achieve screw fixation. Use in acetabulae with < 50% bone stock has also been questioned. Published results have been encouraging in the first decade, with late failures predominantly because of polyethylene wear and aseptic loosening. Dislocation is the most common complication of jumbo acetabular revisions, with an incidence of approximately 10%, and often mandates revision. Based on published results, a hemispherical component with an enhanced porous coating, highly cross-linked polyethylene, and a large femoral head appears to represent the optimum tribology for jumbo acetabular revisions.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):64–7.

Uncemented jumbo cups for revision total hip arthroplasty: a concise follow-up, at a mean of twenty years, of a previous report

Uncemented jumbo cups are commonly used for acetabular revision because they are technically straightforward to implant and provide good intermediate-term results. Understanding long-term survival is particularly important because this method is common and because jumbo cups do not provide notable bone stock restoration. The purpose of the present study was to determine the twenty-year results of jumbo cup use during revision total hip arthroplasty. In the original publication, we reported on eighty-nine patients who underwent revision with an uncemented jumbo cup with a single design (Harris-Galante) prior to 1993. The Harris Hip Score (HHS), radiographic results, and Kaplan-Meier survivorship curves were evaluated. Mean follow-up was twenty years. The mean postoperative HHS was 71 compared with 56 preoperatively (p=0.001). A total of five jumbo cups were revised for aseptic loosening; one, for infection; and one, for recurrent dislocation. Eight liners were revised with retention of the metal acetabular component: six during femoral component revision, one for wear, and one for recurrent dislocations. Twenty-year survivorship was 88% free from aseptic loosening of the metal acetabular component, 85% free from aseptic loosening or radiographic evidence of definite loosening of the metal acetabular component, and 83% free from revision of the metal acetabular component for any reason. The twenty-year results of revision with uncemented jumbo acetabular components demonstrated acceptable clinical outcomes and radiographic stability. These results justify the use of jumbo cups as a common method of acetabular revision.

Options for managing severe acetabular bone loss in revision hip arthroplasty. A systematic review

Revision hip arthroplasty in the presence of severe acetabular bone loss is challenging and requires a solid understanding of current techniques. A literature search of multiple databases applying specific criteria revealed a total of 50 articles of level IV scientific evidence comprising 2415 patients (2480 hips) managed with reinforcement devices (roof-reinforcement rings and anti-protrusio cages), custom-made triflanged acetabular components (CTACs), jumbo cups and tantalum metal (TM) systems. Overall, patients had improved postoperative hip scores for each technique. The use of reinforcement devices resulted in a mean revision rate of 8.2% and a mean complication rate of 29.21%. CTACs were associated with a revision rate of 15.9% and had a complication rate of 24.5%. Jumbo cups were revised in 8.8% of patients and had a complication rate of 18.4%. TM systems had an overall revision rate of 8.5% with complications seen in 18.5% of patients. CTACs had considerably higher revision rates compared to the other techniques. Jumbo cups and TM systems had lower complication rates compared to the use of reinforcement devices and CTACs. The most frequently occurring complications seen throughout the series were aseptic loosening, dislocation and infection.

Reconstruction options for acetabular revision

This article summarizes reconstruction options available for acetabular revision following total hip arthroplasty. A thoughtful methodology to the evaluation and treatment of patients with implant failure after joint replacement is essential to guarantee accurate diagnoses, appropriate triage to reconstruction options, and optimal clinical outcomes. In the majority of patients who undergo acetabular revision, factors such as bone loss and pelvic discontinuity provide a challenge in the selection and implementation of the proper reconstruction option. With advanced evaluation algorithms, imaging techniques, and implant designs, techniques have evolved to rebuild the compromised acetabulum at the time of revision surgery. However, clinical outcomes data for these techniques continue to lag behind the exponential increase in revision hip arthroplasty cases predicted to occur over the next several years. We encourage those involved in the treatment of patients undergoing hip replacement surgery to participate in well-designed clinical studies to enhance evidence-based knowledge regarding revision acetabular reconstruction options.

The Burch-Schneider cage: 9-year survival in Paprosky type 3 acetabular defects. Clinical and radiological follow-up

Revision hip arthroplasty in cases with severe acetabular deficiency represents a technical challenge. The aim of this study was to determine: 1. The 9-year survival of the Burch Schneider anti-protrusio cage (BS-APC) in severe acetabular defects. 2. The migration of the cage and correlation of this with functional outcome. 3. The anticipated functional outcome users can expect in a district general hospital setting in the management of severe acetabular defects. A single-surgeon consecutive series of 30 complex acetabular reconstructions using the BS-APC was retrospectively reviewed. Clinical and radiological follow up at 5-9 years was obtained. Survival was established with revisions and further surgery as different end-points. A radiological analysis using ein bilt roentgen analyse (EBRA) was performed. At a mean follow-up of 85 months (range: 64-118) 26 patients (87%) were alive. Nine-year survival was 95% for revision of BS-APC as an end-point and 92% with any cause of further surgery as an end-point. The mean Oxford Hip Score was 34.5 and UCLA activity score was 4.4. All cases demonstrated evidence of significant migration, but no screws were found to be broken. There was no correlation between cup migration and Oxford hip score (p=0.07). Our non-specialist centre experience suggests the BS-APC should not be dismissed as a reconstruction option in the most severe acetabular defects.

Large acetabular defects can be managed with cementless revision components

BACKGROUND

Optimal techniques for acetabular revision in the setting of major pelvic osteolysis have not been established. Bilobed components, structural grafts, and reinforcement cages have demonstrated 10-24% midterm failure rates. While cementless hemispherical components have been utilized to treat large acetabular defects, most reports have not focused specifically on patients with extensive deficiencies.

QUESTIONS/PURPOSES

We report midterm clinical scores, component revisions, and complications following focal bone grafting and cementless acetabular revision in cases with major periacetabular osteolysis.

METHODS

We identified 30 patients (32 hips) who underwent cementless acetabular revision to treat massive acetabular bone loss at an average followup of 53 months. We excluded three patients lost to followup and two patients who died prior to minimum 24 month followup. Harris Hip Scores were assessed before and after surgery. Postoperative radiographs were evaluated for graft incorporation and component migration. Component revision and component migration are reported as failures.

RESULTS

Mean Harris Hip Score improved from 52.5 (range, 17.7-90.7) to 87.3 (range, 25.3-100) points. Three hips (9%) were revised for aseptic loosening. Three components (10.7%) demonstrated radiographic migration, but were not revised. Complete graft incorporation was seen in 17 cases (68%). There were five major complications (14%).

CONCLUSIONS

Cementless acetabular fixation and bone grafting result in clinical scores and survivorship comparable to other options at midterm followup, with potential for biological fixation.

LEVEL OF EVIDENCE

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

[Acetabular revision surgery with the oblong revision cup : clinical and radiological results of 217 cases]

BACKGROUND

Deficiencies of the acetabular bone stock are an increasing and challenging problem in revision hip surgery. The LOR oblong revision cup is a valuable option in revision hip surgery. The purpose of this study was to assess outcomes with the LOR revision cup in hips with acetabular bone deficiency, analyze the complications, and identify predictors of survival rate.

PATIENTS AND METHODS

From 1996 to 2002, 217 revision surgeries were performed with LOR cups. The mean patient age at operation was 67.5 years (range 29-87 years). The mean postoperative follow-up was 4 years (range 4-100 months). The patients were evaluated clinically and with the Harris hip score (HHS), UCLA score, and WOMAC index. A continuous radiographic assessment was done to detect heterotopic ossifications and radiolucencies or loosening on the basis of the Mayo hip score. Predictors of survival rate were estimated using Kaplan-Meier survivorship analysis.

RESULTS

Twenty-four patients (7.4%) died during the study period. Seven patients (3.1%) had revisions because of aseptic loosening and two patients (0.9%) because of infection. Clinical assessment at follow-up showed a significantly improved mean HHS from 45 points preoperatively to 78 points postoperatively. At the most recent follow-up, patients with a body mass index below 30 or those classified as Charnley A had a significantly better HHS. Because of migration on the latest radiographs, revision was indicated in 4.8% of the cases. The survival rate of all LOR implants based on implant removal was 96% after 40 months and 87% after 80 months. Based on radiographic evidence of loosened implants, the survival rate was 94% after 40 months and 79% after 80 months. Patients with more than two revisions had reduced implant survivorship compared with those having one or two revisions. The factors "age at operation", "gender", "obesity", "ASA score", "Charnley score", and "activity according to the UCLA score" did not influence the survival rate.

CONCLUSION

We recommend this component in revision surgery on the basis of satisfactory clinical and radiological results at a mean of 48 months of follow-up. We identified the number of revisions as a predictor of survival rate.

[Acetabular reinforcement rings in revision total hip arthroplasty: midterm results in 298 cases]

BACKGROUND

Acetabular revision in total hip arthroplasty (THA), especially for loose or migrated cup components with collateral bone loss, remains a great surgical challenge. The aim should always be a functionally favorable reconstruction of the rotation center with sufficient load capacity of the acetabulum. Commonly used implants in Europe are the Mueller ring, the Ganz ring, and the Burch-Schneider cage.

PATIENTS AND METHODS

We report our results of 298 patients (298 hips) with a median follow-up period of 4 (range 0-17) years in a retrospective series.

RESULTS

Follow-up data were available in 224 cases (75%). A radiographic examination was performed in 176 (59%) patients. Another 54 patients (18%) had died in the follow-up period, while another three patients (1%) were lost to follow-up. Eighteen patients (16%) underwent re-revision, in nine cases for aseptic loosening and in the remaining nine cases for infection. In seven additional cases (2%), radiological and clinical failure was found during follow-up. The overall survival rate was 94% at 5 years and 89% at 8 years.

CONCLUSION

Revision THA using acetabular reinforcement rings results in acceptable midterm results. However, septic complications and lysis of the bone graft with consecutive failure of the reinforcement ring remain problematic.