Outcomes of isolated acetabular revision

The impact of retaining the femoral stem in revision total hip arthroplasty: a systematic review, meta-analysis, and meta-regression

INTRODUCTION

The management of well-fixed femoral stems in revision total hip arthroplasty (rTHA) remains a subject of debate, with concerns over potential complications arising from stem retention. This study aimed to investigate the re-revision rates due to aseptic loosening of the stem, overall re-revision rates, dislocation rates, and factors influencing these outcomes in rTHA with a retained well-fixed femoral stem.

MATERIALS AND METHODS

A systematic search was conducted across several databases including PubMed, EMBASE, and CENTRAL to identify pertinent publications from their inception through 2023. We specifically focused on studies that reported outcomes of rTHA with retained well-fixed femoral stems. The study designs incorporated in our research encompassed both cohort studies and case series studies. Thirty-five studies involving isolated acetabular revision and retaining the stem were included, representing a total of 3497 patients. Data extraction was tailored to the study questions. Meta-analyses, meta-regression, and subgroup analyses were conducted to evaluate the outcomes and their relationship with various factors. Pooled results, meta-regression, and subgroup analyses were performed using random-effects models. To assess and reduce bias, we employed Egger's test and the trim and fill method.

RESULTS

The meta-analysis included 3497 patients with a mean follow-up of 9.28 years. The 10-year risk of re-revision after retaining femoral stem using highly cross-linked polyethylene was 1.7% (95% CI 1.1%-2.3%; I2: 60%) for stem aseptic loosening and 8.8% (95% CI 6.2%-11.4%; I2: 78%) overall re-revision. Dislocation risk was 5.7% (95% CI 4.1-7.0%; I2: 61%). Ceramic heads showed lower stem failure risk than metal heads in long-term follow-ups (P < 0.001). The posterolateral approach in revision surgery resulted in better long-term outcomes compared to the direct lateral approach (P < 0.001). Follow-up duration, timeline of study, Harris Hip Score, type of stem fixation, femoral head material, BMI, age, stem age, and surgical approach were evaluated as influential factors on these outcomes.

CONCLUSION

The re-revision rate due to aseptic loosening of the retained stem during rTHA was found to be significantly low, supporting the idea of retaining well-fixed stems during rTHA. The overall re-revision and dislocation rates also presented comparable or better outcomes to prior studies. A range of factors, including the use of highly cross-linked polyethylene and ceramic femoral heads, was found to influence these outcomes.

LEVEL OF EVIDENCE

IV.

PROSPERO REGISTRATION NUMBER

CRD42022351157.

Is Retention of the Acetabular Component at Revision Surgery a Long-Term Solution?

Background

Acetabular retention in revision total hip arthroplasty (THA) may be advantageous, yet long-term survival data is limited. Thus, we investigated long-term survivorship of retained acetabular components in revision THA with analysis of rerevision rate, instability risk, and clinical outcomes.

Methods

We reviewed 98 hips with polyethylene wear and/or osteolysis that were revised with retained acetabular components. Acetabular inclination and anteversion were measured from prerevision radiographs. A retrospective chart review was performed, collecting outcomes of interest including Harris hip score, instability events, and rerevision surgery. Kaplan-Meier analysis was used to calculate the risk of revision over time. Predictors of survival including acetabular component position were analyzed by multiple logistic regression.

Results

Average follow-up was 13 years (range, 5-24). Survivorship rates at 5, 10, 15, and 20 years were 89.7%, 81.6%, 70.8%, and 63.8%, respectively. There was improvement in average Harris hip score (61 to 76, P < .0001). There was a 9% rate of dislocation, and 6 hips (6%) were rerevised for recurrent instability. Overall, there were 23 (23%) rerevisions at an average of 6.1 years with the most common reasons being instability (6%) and aseptic loosening (6%). Use of conventional polyethylene was the only identified independent predictor of rerevision (P = .025).

Conclusions

Retention of a well-fixed acetabular component in revision THA provides acceptable long-term outcomes with a 15-year survivorship of 71%. Instability and aseptic loosening were the most common reasons for rerevision. Surgeons may consider retaining the acetabular component at revision surgery if the implant is well-fixed and well-positioned.

Evaluation results of using GAP II acetabular cage for acetabulum in revision total hip arthroplasty

Acetabular revision arthroplasty with major bone loss is one of the most difficult operations in hip arthroplasty, The graft augmentation prosthesis (GAP) has been designed particularly as an implant for revision acetabular reconstruction. We evaluated the use of GAP II acetabular cage in revision of acetabulum in total hip arthroplasty. From 2009 to 2014, we performed revision total hip arthroplasty in patients with acetabular defects by cage (GAP II) in patients referred to Milad and Erfan Hospitals, Tehran, Iran. We included all patients in class 3a and 3b of Paprosky bone loss classification and type III bone loss according to the system of the American Academy of Orthopedic Surgeons. We used SPSS software Ver 19 and descriptive tests, Chi square and independent t-test were used for analysis. There were 221 men (71.99%) and 86 women (28.01%) with an average age of 51.3 ± 21.7 years (range, 35-86 years). The Modified Harris Hip Score (MHHS) improved significantly at the last follow-up compared with the preoperative MHHS (P < .001). The mean MHHS was 40 (range, 29-44) preoperatively and 92 (range, 86-95) at the last follow-up. There were no major intraoperative complications during acetabular reconstruction. Our findings showed that using GAP II acetabular cage in the restoration of acetabulum in hip revision surgery is significantly desirable.

Survivorship of the retained femoral component after revision total hip arthroplasty: A systematic review and meta-analysis

Objective

This systematic review and meta-analysis aimed to estimate re-revision rates of retained femoral components after revision of total hip arthroplasty (THA).

Methods

Papers were searched in the PubMed, Embase, Web of Science, and Cochrane Library databases with predetermined keywords from January 2000 to January 2022. The studies reporting the re-revision rates of retained stems after revision THA were identified. Pooled rates of re-revision for any reason and aseptic loosening were calculated using a random-effects model or a fixed-effects model based on the results of heterogeneity assessment after the Freeman–Tukey double-arcsine transformation. A meta-regression was performed to explore potential sources of heterogeneity.

Results

There were 20 studies with 1,484 hips that received the isolated cup revision with the femoral component retained. The pooled re-revision rate of retained stems was 1.75% [95% confidence interval (CI) 0.43%–3.65%]. The re-revision rate of retained stems due to aseptic loosening was 0.62% (95% CI, 0.06%–1.55%). The meta-regression showed that the fixation type (cemented or cementless) was related to the re-revision rate for any reason and the re-revision rate for aseptic loosening.

Conclusion

Based on the existing evidence, the isolated cup revision with a stable stem in situ yields low re-revision rates. The cement status of retained stems may influence the survivorship of stems.

Long-Term Survival (up to 34 Years) of Retained Cementless Anatomic Femoral Stem in Patients <50 Years Old

BACKGROUND

There is a paucity of studies longer than 30 years to determine clinical and radiographic results of retained cementless anatomic stem. The purpose of this study is to determine the long-term (up to 34 years) survival rate of the retained cementless anatomic femoral stem in patients <50 years of age.

METHODS

Isolated cup revision was performed with retaining primary cementless anatomic femoral stem in 206 patients (149 men and 57 women). Clinical and radiographic results were monitored at each follow-up. At the latest follow-up, computed tomography scans were carried out in all hips to determine the prevalence of osteolysis. The mean follow-up of the retained femoral stem was 30.3 years (range 27-34). The mean follow-up of the revised cup was 25.5 years (range 22-29).

RESULTS

The mean Harris Hip Score was 91 ± 7.8 points (range 71-100) and the mean Western Ontario and McMaster Universities Osteoarthritis score was 16 ± 7 points (range 7-34) at the final follow-up. The mean University of California, Los Angeles activity score was 7 ± 4 points (range 5-10) at the final follow-up. The overall survival rate of retained cementless femoral stems was 98.9% (95% confidence interval 91-100) at 30.3 years. The survival rate of the revised cup was 93% (95% confidence interval 89-98) at 25.5 years.

CONCLUSION

The rate of aseptic loosening of already osseointegrated femoral stem remains low with ceramic-on-ceramic bearing in young active patients.

The Survival of Well-Fixed Cementless Femoral Component After Isolated Acetabular Component Revision

BACKGROUND

It remains controversial whether isolated acetabular component revision or both component revision surgeries should be performed in patients with stable femoral component. The present study aimed to evaluate the survival of patients with unrevised stable uncemented femoral stem who underwent isolated acetabular component revision.

MATERIAL AND METHODS

A retrospective analysis was conducted in patients who underwent isolated acetabular component revision and had stable uncemented femoral component during revision hip arthroplasty between February 1998 and December 2009. Demographic data of the patients included age, previous surgery, complications, duration between primary and revision surgery, and duration between revision and latest follow-up. Functional results were analyzed using Harris Hip Score (HHS).

RESULTS

Fifteen hips of thirteen patients were included in the study with a mean age of 62.08 ± 12.9 years. Average time from THA to the isolated acetabular revision was 9.2 ± 3.48 years. Average follow-up time from revision to the latest follow-up was 12.39 ± 2.68 years, and femoral components had been followed for an average of 21.6 ± 4.06 years since the time of implantation. Average HHS of the patients were 53 before revision surgery and 81.9 at the last follow-up (p < 0.001). The 10-year survival rate of patients who underwent revision in the femoral component was 100%, whereas their 15-year survival rate was 93.3%. None of the acetabular components required revision.

CONCLUSION

Isolated revision of acetabular component may be considered if there is stable uncemented femoral component in revision THA. Acetabular reconstruction quality, acetabular and unrevised femoral component survival are not affected by retaining well-fixed femoral component.

LEVEL OF EVIDENCE

4, retrospective cohort study.

Adapter sleeves are essential for ceramic heads in hip revision surgery

BACKGROUND

Removing a head during isolated acetabular revision surgery can cause damage to the stem taper surface from extraction tool contact. Implanting a ceramic head on the damaged stem taper might elevate the fracture risk, which can be mitigated with the use of titanium adapter sleeves. The aim of this study was to investigate whether the improved fracture strength of modern generation ceramic heads allows the direct implantation on damaged stem tapers without an adapter sleeve.

METHODS

Finite element models of taper junctions with and without adapter sleeve were generated. Different stem taper damages were modelled to investigate the influence on the ceramic head fracture load under axial compression.

FINDINGS

Heads without adapter sleeves exhibited slightly higher or equal fracture strengths compared with sleeved heads for most scenarios. However, a small metal elevation on the stem taper caused a drastic decrease of the fracture strength if no adapter sleeve was used (-96%). The sleeved head was not influenced by the metal elevation damage.

INTERPRETATION

Adapter sleeves are essential to ensure patient safety and prosthesis longevity whenever implanting ceramic heads on used stem tapers.

Long-term results of isolated acetabular revisions with reinforcement rings: a 10- to 15-year follow-up

PURPOSE

The management of severe acetabular bone deficiency and a stable femoral stem can be a challenging problem in revision hip surgery. Replacement of both the acetabular and femoral component in elderly patients can increase perioperative risks without the certainty of a better functional outcome. We report the long-term outcome of reinforcement rings in isolated acetabular revision to determine whether this procedure allows hip function restoration and implant longevity.

METHODS

A retrospective study was conducted to evaluate the long-term results of isolated acetabular revision in thirty patients with a mean age of 70.6 years. 16 patients (16 hips) received an acetabular reinforcement ring, and 14 patients received a reconstruction cage. Acetabular defects were classified as Paprosky Type II in 16 cases and Type III in 14 cases. The mean follow-up was 11.3 years (range 10-15 years).

RESULTS

Radiographic signs of loosening were found in 9 cases (30%). 4 cases (13.3%) with severe osteolysis and implant migration underwent further revision surgery. All 30 unrevised femoral stems were considered stable. 1 (3%) early dislocation, was conservatively treated. Clinical assessment showed a significantly improved mean Harris Hip Score from 45.1 points preoperatively to 85.4 at the latest follow-up (p < 0.05). The 15-year survival rate was 86.7%.

CONCLUSIONS

Our long-term results showed that in selected patients, isolated acetabular revision with rings or antiprotrusio cages represents a reasonable surgical technique for the management of severe acetabular bone loss. However, concerns about the high radiographic loosening rates are possibly related to low bone ingrowth compared to new porous implants.

Adapter Sleeves Are Not Needed to Reduce the Risk of Fracture of a New Ceramic Head Implanted on a Well-Fixed Stem

The purpose of this study was to assess (1) the prevalence of the fracture of ceramic heads implanted on used trunnions of well-fixed stems without using a titanium adapter sleeve; (2) the prevalence of trunnionosis secondary to fretting and/or corrosion at the trunnion of the well-fixed stem; and (3) clinical and radiographic results and the survival rate of the revised acetabular components. Eighty-eight patients (100 hips) underwent isolated revision of the acetabular components for polyethylene wear and osteolysis of the acetabulum. The study group consisted of 70 men and 18 women with a mean age of 52.8 years (range, 31-54 years) when the primary total hip arthroplasty was performed. Evidence of fretting and corrosion of the trunnion of all prostheses was examined macroscopically using a magnifying lens. Degree of fretting and corrosion of the trunnion was assessed using a 4-point scoring technique. A new 36-mm alumina delta ceramic head was implanted on the trunnion of a well-fixed stem without using a titanium adapter sleeve in all hips. The mean follow-up after revision of the acetabular component was 12.8 years (range, 10-14 years). Among the 100 new ceramic heads implanted on a well-fixed stem, no fracture of the ceramic head occurred at a mean follow-up of 12.8 years. The median fretting and corrosion scores for the trunnions were 1.5±1.1 and 1.3±0.9 points, respectively. The mean Harris hip score at the final follow-up was 89±15 points (range, 63-100 points). Survivorship of the revised acetabular components at 14 years was 95% (95% confidence interval, 87.6%-98.6%). [Orthopedics. 2018; 41(3):158-163.].

Isolated revision of the acetabular component using alumina-on-alumina bearings without a metal sleeve: A preliminary study

INTRODUCTION

There has been a debate on the use of ceramic-on-ceramic coupling with the retained femoral stem in isolated acetabular revision. The purpose of this study was to retrospectively review the results and complications of isolated revision of the acetabular component using alumina-on-alumina bearings.

METHODS

Between August 2010 and December 2013, 22 patients (23 hips) with a mean age of 60.74 years (40-73) underwent isolated revision of the acetabular component from metal-on-polyethylene to alumina-on-alumina bearings without using a metal sleeve on the undamaged trunnion. All patients completed clinical and radiographic evaluation.

RESULTS

At a mean follow-up of 3 years (2-5.5), all patients had a significant improvement in the clinical outcome, including Harris Hip Score (84.9 vs. 43, p < 0.001), West Ontario McMaster University Osteoarthritis Index Score (14.4 vs. 49.2, p < 0.001), and visual analogue pain score (1.42 vs. 6.63, p < 0.001). Complications included one aseptic loosening of the acetabular component and three noisy hips (click only). No fracture of the ceramic bearings, dislocation, infection, or squeaking noise were observed in any of the patients.

CONCLUSION

Isolated revision of the acetabular component to alumina-on-alumina bearings on the undamaged trunnion may be considered if there is no available titanium sleeves. Our study showed a satisfactory early outcome with minimal complications. However, a longer term follow-up study is necessary.

Isolated acetabular revision with femoral stem retention after bipolar hip arthroplasty

INTRODUCTION

In bipolar hemiarthroplasty, migration of the outer cup component into the acetabular cup, with evidence of severe osteolysis in the acetabulum, commonly occurs without loosening of the femoral component. The merits of retaining the stable femoral component in these cases have been debated. Our study aimed to determine whether revision of the acetabular component in isolation could be successfully performed.

MATERIALS AND METHODS

The data of 54 patients (61 hips), 44 women, and 10 men, aged 67.7 (range 47-86) years at the time of the index revision, were analyzed. The average time from primary operation to revision surgery was 14.9 (range 1.0-27.0) years, with an average follow-up time after revision of 5.2 (range, 1.0-18.7) years. Indications for acetabular revision included migration of the outer cup component (N = 55), disassembly of the bipolar cup (N = 4), and recurrent dislocation (N = 2). Fixation of the femoral stem was cementless in 49 hips and cemented in 12. Bone grafting for osteolysis of the proximal femur around the stem was performed in six hips. An acetabular reinforcement ring with a cemented cup was used in 31 hips, with cementless cup fixation in 29 hips, and cemented cup in one case.

RESULTS

On average, the Harris hip score improved from 57.0 ± 21.6 to 87.4 ± 6.40 points after revision. Two cases of femoral periprosthetic fracture were treated with osteosynthesis 3 year post-revision. There was no evidence of loosening of the femoral stem or subsidence, with a non-progressive radiolucent line <2 mm identified in one case. There was no incidence of dislocation or deep infection, and all components were judged to be stable at the final follow-up.

CONCLUSION

Isolated acetabular revision can be reliably performed in cases of failed bipolar hemiarthroplasty with a well-fixed femoral component.

Complications Are Not Increased With Acetabular Revision of Metal-on-metal Total Hip Arthroplasty

BACKGROUND

Isolated revision of the acetabular component in the setting of total hip arthroplasty has an increased risk of dislocation. With local soft tissue destruction frequently associated with failed metal-on-metal (MoM) bearings, it is presumed that acetabular revision of these hips will have even greater risk of complications. However, no study directly compares the complications of MoM with metal-on-polyethylene (MoP) acetabular revisions.

QUESTIONS/PURPOSES

In the context of a large database analysis, we asked the following questions: (1) Are there differences in early medical or wound complications after isolated acetabular revision of MoM and MoP bearing surfaces? (2) Are there differences in the frequency of dislocation, deep infection, and rerevision based on the bearing surface of the original implant?

METHODS

A review of the 100% Medicare database from 2005 to 2012 was performed using International Classification of Diseases, 9th Revision and Current Procedural Terminology codes. We identified 451 patients with a MoM bearing and 628 patients with a MoP bearing who had an isolated acetabular revision and a minimum followup of 2 years. The incidence, odds ratios, and 95% confidence intervals for early medical or wound complications were calculated using a univariate analysis at 30 days with patient sex and age group-adjusted analysis for blood transfusion. The incidence, odds ratio, and 95% confidence intervals for dislocation, deep infection, and rerevision were calculated using a univariate analysis at 30 day, 90 days, 1 year, and 2 years using a subgroup analysis with the Cochran-Mantel-Haenszel test to adjust for patient gender and age groups.

RESULTS

There were no differences between the MoM and MoP isolated acetabular revisions in the incidence of 30-day local complications. There was a greater risk of transfusion in the MoP group than the MoM group (134 of 451 [30%] versus 230 of 628 [37%]; odds ratio [OR], 0.731; 95% confidence interval [CI], 0.565-0.948; p = 0.018). There were no differences at 2 years between the MoM and MoP acetabular revisions in the incidence of dislocation, infection, or rerevision. When analyzed by patient sex and age group, there were more infections in the age 70 to 79 years MoP group compared with MoM (10 of 451 [5%] versus 29 of 628 [10%]; OR, 4.47; CI, 1.699-11.761; p = 0.001).

CONCLUSIONS

There were high rates of dislocation, infection, and rerevision in both revision cohorts. The rate of dislocation was not greater after acetabular revision of MoM bearings at 2 years. Based on these findings, clinicians should counsel these patients preoperatively about the risks of these complications. Dual-mobility and constrained components have specific advantages and disadvantages in these settings and should be further studied.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Isolated revision of an acetabular component to a ceramic-on-ceramic bearing in patients under 50 years of age

A number of studies have reported satisfactory results from the isolated revision of an acetabular component. However, many of these studies reported only the short- to intermediate-term results of heterogeneous bearing surfaces in a mixed age group. We present our experience of using a ceramic-on-ceramic (CoC) bearing for isolated revision of an uncemented acetabular component in 166 patients (187 hips) who were under the age of 50 years at the time of revision. There were 78 men and 88 women with a mean age of 47.4 years (28 to 49). The most common reason for revision was polyethylene wear and acetabular osteolysis in 123 hips (66%), followed by aseptic loosening in 49 hips (26%). We report the clinical and radiological outcome, complication rate, and survivorship of this group. The mean duration of follow-up was 15.6 years (11 to 19). The mean pre-operative Harris hip score was 33 points (1 to 58), and improved to a mean of 88 points (51 to 100) at follow-up. The mean pre-operative total Western Ontario and McMaster Universities Osteoarthritis Index score was 63.2 (43 to 91) and improved to 19.8 points (9 to 61) post-operatively. Overall, 153 of 166 patients (92%) were satisfied with their outcome. Kaplan-Meier survivorship analysis, with revision or radiological evidence of implant failure (13 patients, 8%) as end-points, was 92% at 15 years (95% confidence interval 0.89 to 0.97). Isolated revision of a cementless acetabular component using a CoC bearing gives good results in patients under 50 years of age.

Early Outcomes of Titanium-Based Highly-Porous Acetabular Components in Revision Total Hip Arthroplasty

Titanium-based highly-porous metal cups have been introduced as a relatively new alternative for enhanced acetabular fixation during revision THA; limited number of studies have evaluated its outcomes. We aimed to assess the clinical, functional, and patient-reported outcomes following the use of new generation highly-porous titanium acetabular implants in the revision setting. Seventy-one revisions were (1:1) matched to a conventional porous-coated cohort and were followed-up clinically and radiographically for at least 2-years. Non-significant differences in overall aseptic-survivorship were found across all types of acetabular defects comparing both cohorts (P=0.3). The overall HHS, UCLA, and SF-36 scores were similar between both cohorts. It remains to be seen if the great potential for enhanced osseointegration translates into improved long-term survivorship compared to conventional-porous devices.

Clinical and radiological results over the medium term of isolated acetabular revision

Acetabular cup loosening is associated with pain, reduced function, and instability of the implant. If such event happens while the femoral implant is in a satisfactory position and is well fixed to the bone, isolated acetabular revision surgery is indicated. The aim of this single-center retrospective study was to evaluate the clinical and radiological results over the medium term (12-month follow-up mean 36, max 60) of isolated acetabular revisions surgery using a porous hemispheric revision shell matched with a cemented all-poly cup and large diameter femoral head (>32). 33 patients were enrolled. We collect any relevant data from the clinical board. Routine clinical and radiographic examinations were performed preoperatively; the postoperative follow-up was made at 1, 3, and 6 months and yearly thereafter. At the last available follow-up, we report satisfactory improvement of functional scores in all the patients; 2 patients (6.1%) showed thigh pain and only 4 hips (12.11%) presented mild groin pain; all the femoral components are well fixed and there were no potential or pending rerevisions. With bias due to the follow-up and to the retrospective design of the study, we report clinical, functional, and radiological satisfactory results.

One-component revision in total hip arthroplasty: the fate of the retained component

The purpose of the present study was to evaluate the long-term outcome of the unrevised part in one-component total hip arthroplasty revision (index operation). Forty-four patients (46 hips) with a mean age of 58years at the time of the index operation were included. At the final follow-up, 4 of the 19 (21%) unrevised acetabular components and 6 of the 27 (22%) unrevised femoral components were subsequently revised at a mean time of 14 and 11years from the index operation, and 22 and 24years from the primary operation, respectively. We concluded that revision of a stable component is not justifiable on the basis of its long duration in use or non-ideal position or possible loosening on radiographs.

Revision Total Hip Arthroplasty with Retained Acetabular Component

BACKGROUND

Aseptic loosening and osteolysis commonly limit the survivorship of total hip prostheses. Retention of a well-fixed acetabular component, rather than full acetabular revision, has multiple advantages, but questions have lingered regarding the clinical success and prosthetic survivorship following this procedure. We examined the impact of acetabular component position, polyethylene type, liner insertion technique, femoral head size, and simultaneous revision of the entire femoral component (as opposed to head and liner exchange) or bone-grafting on mid-term to long-term prosthetic survival following such limited revisions.

METHODS

One hundred hips in 100 patients with osteolysis, polyethylene wear, or femoral component loosening underwent revision total hip arthroplasty with retention of the acetabular component. Acetabular component inclination and anteversion were measured on prerevision radiographs and were categorized according to predetermined positional safe zones (inclination of 35° to 55° and anteversion of 5° to 25°). Operative reports were reviewed for femoral head size, polyethylene liner type (conventional or highly cross-linked), liner insertion technique (use of the existing locking mechanism or cementation), whether the patient had revision of the entire femoral component, and use of bone graft. Outcomes of interest included the Harris hip score, University of California at Los Angeles (UCLA) activity score, episodes of instability, and need for repeat revision.

RESULTS

At an average of 6.6 years (range, two to fourteen years) postoperatively, the Harris hip and UCLA activity scores were both significantly improved compared with the preoperative scores (p < 0.0001 and p < 0.01, respectively). Overall, the failure rate was 13%. In addition, 6% of the patients had postoperative instability. Hips in which the acetabular component was outside of the safe zone for inclination had a higher rate of failure (p = 0.048). Use of conventional, rather than highly cross-linked, polyethylene at the time of revision was also associated with an increased rate of repeat revision (p = 0.025).

CONCLUSIONS

Revision total hip arthroplasty with retention of the acetabular component is associated with good outcomes in hips with an appropriately positioned, well-fixed acetabular component. Acetabular components outside the safe zone for inclination were at a higher risk for failure, as was use of conventional polyethylene.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Acetabular revision arthroplasty: using the Hastings bipolar head to enable retention of a well-fixed monoblock stem

We describe a novel technique of combining the Hastings bipolar head, matched in size to the acetabular cup liner, with a fixed, cemented monoblock stem allowing for isolated uncemented acetabular revision arthroplasty.

AIM

To assess patient clinical and radiological outcomes after isolated uncemented acetabular revision arthroplasty using the Hastings bipolar head.

METHODS

Clinical outcome was assessed with the Oxford and WOMAC hip scores.
Radiographs were assessed preoperatively for acetabular defects. Post operative osseointegration of the acetabular cup was then classified and the femoral stem was examined for signs of loosening.

RESULTS

Nine acetabular components were revised in eight patients. Preoperative acetabular defects ranged from Paprosky type 1 to 3A. There were no significant intra or postoperative complications. At a mean final follow-up of 15 months, the Oxford hip score improved from an average of 17.5 preoperatively to 44.1, and the WOMAC score had improved from 44.1 to 90.9. Eight acetabular cups demonstrated three or more signs of osseointegration with the remaining cup showing two signs. There were no signs of loosening of the retained femoral stems.

CONCLUSION

These short term results of the use of the Hastings bipolar head in isolated uncemented acetabular revision arthroplasty demonstrate good patient outcomes, reduced morbidity, decreased technical difficulties for the surgeon and reduced expense for the health service.

Modular sleeves with ceramic heads in isolated acetabular cup revision in younger patients-laboratory and experimental analysis of suitability and clinical outcomes

PURPOSE

One possibility in hip arthroplasty revisions is to combine a modular ceramic head with an adapter or sleeve in isolated acetabular cup replacement. This study consisted of an experimental part to analyse the reliability of taper damage predictions, and a clinical part to analyse the outcomes of modular ceramic head implantation in a case series of isolated cup replacements.

METHODS

Analysis of scratch size on 11 explanted hip stems were examined macroscopically and by stereomicroscopy to classify damage to the conical taper. The second part consisted of a prospective analysis of isolated cup revisions using a modular ceramic head, performed in two orthopedic centres.

RESULTS

Analysis of scratch size on the taper yielded inter-observer correlations of 0.545-0.909; comparison with stereomicroscopic data recordings yielded a moderate correlation, with values between 0.545 and 0.090. The clinical study included 47 isolated acetabular cup revisions involving modular ceramic heads. Ceramic head failure did not occur during the average clinical and radiological observation period of 26 months. Mean Harris Hip Score (HHS) at follow-up was 70 points.

CONCLUSION

From these results, it can be concluded that damage to the implanted stem taper cannot be reliably predicted intraoperatively. Nevertheless, the clinical outcomes did show that there were no problems with the ceramic heads over the short observation period. The application of modular ceramic heads in younger patients requiring isolated cup replacement requires proper risk-benefit analysis, but is possible and appears to be a safe procedure.

A dual-mobility cup reduces risk of dislocation in isolated acetabular revisions

BACKGROUND

Isolated acetabular revisions using standard cups are at risk of dislocation. The introduction of a nonconstrained dual-mobility cup was designed to improve prosthetic stability without increasing loosening rates, but it is unclear whether the risk of dislocation is reduced.

QUESTIONS/PURPOSES

We therefore determined: (1) if the rate of dislocation in isolated acetabular revisions is lower with a dual-mobility cup, (2) implant survival, (3) patient function, and (4) radiographic incidence of migration, loosening, and osteolysis.

METHODS

We prospectively followed 33 selected patients who underwent isolated acetabular revisions with a minimum of 2 years' followup (mean, 3 years; range, 2-5 years). In 24 patients a stainless steel dual-mobility cup was cemented into an antiprotrusio cage, whereas in nine we used a hyaluronan dual-mobility revision cup with a foramen hook and superior and posterior flanges screw fixations. We determined Harris hip (HHS) and WOMAC scores and examined radiographs for migration, loosening, and osteolysis.

RESULTS

There were no dislocations. Survivorship rates of the femoral and acetabular components were 97% at 5 years; the rerevision rate for any reason was 3%. At last followup, the mean HHS increased from 48 points preoperatively to 86 points. No patients had progressive osteolysis, component migration, or loosening on radiographs.

CONCLUSION

In this select group of isolated acetabular revisions, our data suggest the use of a dual-mobility cup reduced the risk of dislocation without increasing loosening from 2 to 5 years.

LEVEL OF EVIDENCE

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

Alumina heads minimize wear and femoral osteolysis progression after isolated simple acetabular revision

BACKGROUND

Patients with THA requiring cup revision for acetabular osteolysis may have a stable stem component without loosening. However, it is unclear whether isolated cup revision halts femoral osteolysis progression.

QUESTION/PURPOSES

We asked (1) whether and to what degree osteolysis progresses after isolated acetabular revision with a change of the femoral head and (2) whether an alumina or metal bearing better reduces osteolysis progression and wear with a polyethylene (PE) cup.

METHODS

We retrospectively evaluated 150 patients who underwent 165 acetabular revisions but no treatment for proximal femoral osteolysis in hips with stable femoral components. Mean age at revision was 63 years (range, 48-74 years). All hips received a new PE cup; 83 hips received new alumina heads and 82 new metal heads. Radiographs (mean followup, 15 years; range, 10-25 years) were assessed to measure osteolysis, loosening, and PE wear. Revisions of the femoral stem were recorded.

RESULTS

An isolated cup revision with a change of the femoral head halted femoral osteolysis progression for 10 years in 133 hips (81%), with a greater percentage without progression in hips with alumina heads (99% versus 62% with metal head). Alumina heads were better than metal heads at reducing the area of osteolysis progression (47 versus 250 mm(2)) and wear (0.07 versus 0.14 mm/year) and increasing the survival probability before femoral revision (98% versus 85% at 15 years' followup).

CONCLUSIONS

An isolated cup revision with a new alumina femoral head (in hips that have a stable stem component without loosening) usually halts femoral osteolysis progression (no change or osseous restoration) over 10 years if the osteolysis is less than 1000 mm(2).

LEVEL OF EVIDENCE

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Function and survival after revision of hip resurfacing

The purpose of this study was to compare functional outcome and survival of isolated acetabular, isolated femoral and both component revision after failure of primary Birmingham Hip Resurfacing. The Oswestry Outcome Centre prospectively collected data on 5000 hip resurfacing between 1997 and 2002. Of these, 182 hips were revised: 8% had revision of the acetabular component only, 42% had revision of the femoral component only to conventional stemmed prosthesis, and 50% had revision of both components to conventional total hip arthroplasty (THA). We used a postal questionnaire to assess function by Harris and Merle d'Aubigné and Postel hip scores and determined survival using re-revision as an endpoint. In patients with isolated acetabular revision, the median Harris hip score (HHS) was 74 at a mean of 4.5 years follow up. Isolated femoral revision had a median HHS of 82 at a mean of 3.8 years. When both components were revised, the median HHS was 85 at a mean of 4 years. We observed no difference in HHS between the groups. There was an average survival of 92% at 10 years. Survival was significantly lower for isolated acetabular revision (75%) than isolated femoral (93%) or both component revision (96%).

A well-fixed femoral stem facing a failed acetabular component: to exchange or not? A 5- to 15-year follow-up study

INTRODUCTION

There is no consensus about the necessity of exchanging a stable femoral component during revision total hip arthroplasty (RTHA) when only the acetabular component requires replacement. Sparing the femoral component reduces morbidity, but can make acetabular replacement technically more difficult. Moreover, the outcome of the retained femoral component is also a question, especially with older implants.

HYPOTHESIS

Isolated acetabular component RTHA results in lower surgical morbidity, and does not increase the risk of later femoral complications.

PATIENTS AND METHODS

Eighty-nine patients, mean age 68, underwent surgery (anterior approach on traction table) for isolated acetabular component revision between 1994 and 2005. The femoral component had been implanted a mean 10.5 years before revision.

RESULTS

Fifteen patients died, mean age 84.5. Eleven patients, mean age 81.3, were lost to follow-up and four underwent revision due to a subsequent infection (range 14 months - 11 years). Fifty-nine patients were evaluated after a mean 8.6 years (range 4 - 15 years). At follow-up the mean Harris score was 89.2 [IC=6.89; 44 - 100] and the mean Merle d'Aubigné score was 15.3 [IC=1.57; 11 - 18]. Five patients (5.6%) underwent surgery again due to postoperative dislocation. Six patients underwent surgery for recurrent acetabular loosening due to allograft resorption. The size of the bone defects did not increase the risk of these failures (P>0.6). Fractures occurred in two femoral components 6 and 9 years after revision. Polyethylene wear occurred in three patients requiring two repeat revisions at 6 and 7 years. In both cases the femoral component included a titanium head, which caused the wear. Implant survival at 8.6 years was 85.16 ± 0.117% all causes of revision combined, 88.47 ± 0.113% if infectious causes were excluded and 93.6 ± 0.07% if only cases of acetabular component failure were taken into account.

CONCLUSION

Intermediate term outcomes are satisfactory if stable femoral components are retained. Nevertheless, this procedure should be performed in situations of correctly oriented modular components. In single piece (monoblock) femoral implants, or in implants with a history of failure, this technique should be restricted to elderly and/or fragile patients.

LEVEL OF EVIDENCE

Level IV, Retrospective study.

A comparative study of the posterolateral and anterolateral approaches for isolated acetabular revision

PURPOSE

Although isolated revision of the acetabular component has become an increasingly common option for revision hip surgery, opinions differ regarding the ideal surgical approach for reducing postoperative instability. The purpose of this study was to compare the clinical and radiographic results of isolated acetabular revision performed using a posterolateral and an anterolateral approach.

MATERIALS AND METHODS

The authors retrospectively compared the clinical and radiographic results of isolated acetabular revision performed in 33 hips using a posterolateral approach with those performed in 36 hips using an anterolateral approach. All procedures were performed by a single surgeon and all patients received the same postoperative protocol. Mean duration of follow-up was 4.6 years (range 2-13.2).

RESULTS

Mean postoperative Harris hip scores were similar in the posterolateral and anterolateral groups (86.5 and 87.2 points, respectively). In the entire series of 69 hips, 6 (9%) underwent re-revision of the acetabular component because of aseptic cup loosening in 4, recurrent dislocation in 1, and deep infection in 1. No significant difference was found between the two groups with respect to complication or re-revision rates, but the dislocation rate in the anterolateral approach group was significantly lower than that in the posterolateral group (0 vs. 12%, p = 0.047).

CONCLUSION

Isolated acetabular revision performed using an anterolateral approach seems to be the more viable option in selected patients, and in particular, it has a significantly lower postoperative dislocation rate than posterolateral acetabular revision.