Wear and periprosthetic osteolysis of modular, hemispheric acetabular cups]

Osteolysis associated with polyethylene wear has become one of the most prevalent complications associated with uncemented modular, hemispherical cups. Sixty-five consecutive total hip arthroplasties (ABG i, Howmedica, Stryker) were followed 6-12 years. Cumulative survivorship for the cup was 55.7% after 10 years. There were 20 cups revisions because of polyethylene wear and periprosthetic osteolysis (14 cups) or cup loosening (6 cups). Stability was assessed intraoperatively, 14 cups were revised, whereas 6 new polyethylene cups were cemented into stable metal-back of acetabular component. The average annual wear of revised cups was 0.32 mm. The annual wear of not revised cups was 0.12 mm. The differences were statistically significant (p = 0.002). The mean area of osteolysis was 472 mm2 (SD 257 mm2). There was no significant correlation between wear and area of osteolysis. There was significant correlation R = 0.54, p = 0.014) between time to revision and area of osteolysis. There were no significant differences of wear of polyethylene inlay or area of osteolysis between stable and unstable acetabular cups.     

Results at a minimum of 10 years of follow-up for AMS and PerFix HA-coated cementless total hip arthroplasty: impact of cross-linked polyethylene on implant longevity

Purpose

The purpose of this study was to report results at a minimum of 10 years for hydroxyapatite (HA) coating on the titanium arc-sprayed cementless total hip arthroplasty (THA) and to evaluate the impact of cross-linked polyethylene (XLPE) on implant longevity.

Methods

A total of 131 consecutive primary THAs in 123 patients using an AMS acetabular cup and a PerFix HA stem were retrospectively reviewed. Conventional PE was used for 62 hips (CPE group) and cross-linked PE for 69 hips (XLPE group), with mean follow-up periods of 13 and 11.5 years, respectively. These patients were reviewed using the Japanese Orthopaedic Association (JOA) Hip Score and evaluated in terms of PE wear, osteolysis, and implant survival.

Results

The JOA score improved from 42.6 to 83.9 points at the final follow-up. The mean wear rate of 0.12 mm/year in the CPE group was significantly greater than that of XLPE at 0.007 mm/year. In the CPE group, ten (16.1 %) and two (3.2 %) hips, respectively, underwent PE exchange due to severe wear and acetabular revision due to loosening associated with osteolysis. Three patients had revision in the XLPE group: one cup for aseptic loosening, one PE for recurrent dislocation, and one stem for neck fracture. No evident osteolysis was seen in the XLPE group. Kaplan–Meier survivorship with any revision as the end point shows that the 12-year survival rate was 97.7 % for cups, 93.8 % for PE liners, and 99.2 % for stems. Multivariate analysis revealed that the use of XLPE significantly reduced the risk of revision, with the odds ratio (OR) of 4.3.

Conclusions

AMS and PerFix HA components in this series show excellent implant fixation; however, high rates of PE wear and subsequent osteolysis were limiting factors in long-term success. Low wear rates with XLPE suggest improved implant longevity.     

Catastrophic failure of an uncemented acetabular component due to high wear and osteolysis: an analysis of 154 omnifit prostheses with mean 6-year follow-up

BACKGROUND: The purposes of this study were (1) to evaluate the wear pattern of the hydroxyapatite-coated "Dual Radius" Omnifit cup, (2) to investigate whether wear is correlated to any demographic or prosthesis-related factors, and (3) to describe micromotion of both the cup and the stem. PATIENTS AND METHODS: 154 hips were implanted between 1990 and 1996 and followed for an average of 6 years. Wear was measured according to the "Charnley-duo" method and, in 79 hips, with radiostereometry IRSA). RSA was also used to evaluate micromotion. We analyzed the femoral heads using scanning electron microscopy, energy dispersive X-ray spectroscopy and an atomic force microscope. RESULT: 66 cups were revised and had a mean annual wear of 0.32 mm compared to 0.12 mm in hips not revised. Osteolytic processes were observed in 35 hips but at revision osteolysis was present in 51 cases. 43/66 sockets were loose. Micromotion evaluated by RSA, weight, age, side, size of cup, screws, polyethylene thickness or shelf-life of the polyethylene did not correlate to wear, whereas male gender did. INTERPRETATION: It is still unclear why about half of our cases had an abnormal wear rate. Annual wear exceeding 0.2 mm is prognostic of late failure and should be considered a warning sign.     

Midterm survivorship of a press-fit, plasma-sprayed, tri-spike acetabular component

Press-fit acetabular cups without screw holes can limit migration of particulate wear debris and reduce risk of acetabular osteolysis and device loosening. The Tri-Spike cup (Biomet, Inc, Warsaw, Ind) includes a titanium alloy plasma spray porous surface and does not require screw fixation. We retrospectively examined the incidence of cup loosening and acetabular osteolysis after implantation of 45 cups (44 patients) with mean follow-up of 7.3 years (range, 4-9 years). Only one patient (one cup) had evidence of less than 1 mm of retroacetabular radiolucency at 3 years (nonprogressive), which was found to remain firmly fixed during revision of the aseptically loosened femoral component. No cups were removed or revised at latest follow-up. Projected Kaplan-Meier survivorship at 9 years was 100% for cup loosening/revision and 97.8% for radiolucency.     

Cementless hemispheric acetabular component in total hip replacement

A series of 198 total hip arthroplasties was performed using a porous-coated, hemispheric press-fit cup. One hundred and twenty-seven cups were available for clinical and radiological examination at mean follow-up of 10.6 years. The mean age at the index procedure was 61.2 years. The mean Harris hip score at final follow-up was 89.8. Three cups were revised for aseptic loosening and two liners were changed for eccentric wear and pelvic osteolysis. Nine additional patients showed mild or suspected osteolysis. Two cups were rated "fibrous" stable. There was no correlation between additional screw fixation of the press-fit cup and osteolysis or revision.     

Reconstruction of the rotation center of the hip after oblong cups in revision total hip arthroplasty

Background

The preoperative bone defect and the reconstruction of the center of rotation of the hip are critical in acetabular revision surgery. Uncemented oblong cups are employed in order to manage these issues. We analyzed the clinical results and rates of revision of two different uncemented oblong cups, the reconstruction of the center of rotation of the hip, as well as the rate of radiological loosening and possible risk factors.

Materials and methods

Forty-five patients (46 hips) underwent acetabular revision surgery using two different uncemented oblong cups. We assessed the clinical results and the survival rate for revision and aseptic loosening. Intraoperative bone loss was classified according to Paprosky, and acetabular reconstruction was assessed according to Ranawat. The mean follow-up was 7.2 years (range 4–11 years).

Results

There were four re-revisions (three due to aseptic loosening); the survival rate for re-revision due to aseptic loosening was 60.1 % at seven years. The mean distance between the center of the femoral head prosthesis and the approximate center of the femoral head improved from 21.5 to 10.2 mm. Thirteen cups showed radiological loosening; the survival rate for radiological loosening at seven years was 40.54 %. A smaller postoperative horizontal distance was correlated with cup loosening.

Conclusions

Although optimal acetabular reconstruction can be achieved by using oblong uncemented cups in revision hip surgery, the clinical and radiological results are not encouraging. Excessive medialization of the cup may increase the rate of loosening.     

Catastrophic failure of an uncemented acetabular component due to high wear and osteolysisAn analysis of 154 Omnifit prostheses with mean 6-year follow-up

Background?The purposes of this study were (1) to evaluate the wear pattern of the hydroxyapatite-coated “Dual Radius” Omnifit cup, (2) to investigate whether wear is correlated to any demographic or prosthesis-related factors, and (3) to describe micromotion of both the cup and the stem.Patients and methods?154 hips were implanted between 1990 and 1996 and followed for an average of 6 years. Wear was measured according to the “Charnley-duo” method and, in 79 hips, with radiostereometry (RSA). RSA was also used to evaluate micromotion. We analyzed the femoral heads using scanning electron microscopy, energy dispersive X-ray spectroscopy and an atomic force microscope.Result?66 cups were revised and had a mean annual wear of 0.32?mm compared to 0.12?mm in hips not revised. Osteolytic processes were observed in 35 hips but at revision osteolysis was present in 51 cases. 43/66 sockets were loose. Micromotion evaluated by RSA, weight, age, side, size of cup, screws, polyethylene thickness or shelf-life of the polyethylene did not correlate to wear, whereas male gender did.Interpretation?It is still unclear why about half of our cases had an abnormal wear rate. Annual wear exceeding 0.2?mm is prognostic of late failure and should be considered a warning sign.     

Modular acetabular reconstructive cup in acetabular revision total hip arthroplasty at a minimum ten year follow-up

Purpose

Modular acetabular reconstructive cups have been introduced in an attempt to offer initial rigid fixation by iliac lag screws and ischial pegs, to support bone grafts with a flanged metal socket, and to restore original hip center in acetabular revision. The purpose of this study was to clarify minimum ten year follow-up results of this cup system with morsellised allografts in revision cases.

Methods

We retrospectively investigated 54 acetabular revisions at a mean of 11 years (range, ten to 14 years). The indications were Paprosky’s type 2B (eight hip), 2C (eight hips), 3A (23 hips), 3B (nine hips), and 4 (six hips).

Results

Using aseptic loosening as the endpoints, the survival rate was 89.3 % (95 % CI 81–98). Radiographically, one type 3A hip, three type 3B hips and one type 4 hip showed aseptic loosening while no type 2 hips or no cemented cups showed loosening.

Conclusions

The modular reconstructive cups for acetabular revision showed bone stock restoration and stable implantation.     

Systematic review on outcomes of acetabular revisions with highly-porous metals

Purpose

The purpose of this study was to systematically review the literature and report the clinical and radiographic outcomes of highly-porous acetabular cups in revision settings.

Method

A literature search of four electronic databases of EMBASE, CINAHL-plus, PubMed, and SCOPUS yielded 25 studies reporting the outcomes of 2,083 revision procedures with highly-porous acetabular components. There was lack of high quality evidence (level I and level II studies) and only two studies with level III evidence, while the remainder were all level IV studies. In addition, a majority of the studies had small sample sizes and had short to mid-term follow-up. The mean age of the patients was 65 years (range, 58–72 years) and the mean follow-up was 3.6 years (range, two to six years). Outcomes evaluated were aseptic survivorship, Harris hip scores, migration rates, incidence of peri-acetabular radiolucencies and radiographic restoration of the hip centre.

Results

The mean aseptic survivorship was 97.2 % (range, 80–100 %). The Harris hip scores improved from a mean pre-operative score of 42 points, (range, 29–75 points), to a mean postoperative score of 79 points (range, 69–94 points). The mean incidence of cup migration and prevalence of peri-acetabular radiolucencies was 2.4 % (range, 0–8.8 %) and 4.6 % (range, 0–19 %), respectively, at final follow-up. The vertical hip centre-of-rotation was restored significantly from a mean of 39.2 mm (range, 27.6–50 mm) pre-operatively, to a mean of 24.1 mm (range, 7.4–47 mm), postoperatively.

Conclusion

The short-term clinical and radiographic results of highly-porous metals in revision hip arthroplasty are excellent with a low rate of loosening in the presence of both major and minor bone loss.     

Uncemented third-generation ceramic-on-ceramic total hip arthroplasty using metal acetabular shell with direct taper locking liner

Background

The ceramic-on-ceramic (CoC)-bearing couple in total hip arthroplasty (THA) was developed to reduce the wear debris and osteolysis. Although the mechanical strength of third-generation ceramic has improved over previous generations, the risk of osteolysis and ceramic fracture is still an important concern.

Methods

We studied 124 uncemented THAs with third-generation CoC-bearing couple implanted between 2000 and 2004. The ceramic liner and head were secured with the direct taper locking mechanism. One hundred and eleven hips were followed-up for minimum of 8 years, with an average follow-up period of 10.1 years (range 8.0–12.8 years). Patients were evaluated with a particular emphasis on the prevalence of the osteolysis and the ceramic fracture.

Results

The survivorship with the end point as implant revision for any reason was 94.9 % (95 % confidence intervals 90.0–99.3 %) at 12.8 years. Revisions were performed because of one ceramic liner fracture, three dislocations, and two deep infections. No radiographic evidence of wear or osteolysis was observed. The preoperative Merle d’Aubigne and Postel hip score increased from 11.6 to 17.1.

Conclusions

Patients, who received third-generation CoC THA had no detectable wear and osteolysis. One ceramic fracture occurred, and the main reason for revision was dislocation.     

Preliminary report with the Regenerex™ revision shell: clinical, functional, and radiologic evaluations with a mean follow-up of 25 months

Background

Acetabular cup loosening is the primary reason of revision in total hip arthroplasty; this usually occurs as a result of implant fixation failure. There are a variety of surgical hardware and strategies available to address this problem that is one of the most challenging circumstances in hip surgery. The purpose of this prospective nonrandomized study is to present our preliminary results in the Ist Orthopaedic and Traumatology Unit of Pisa University with Regenerex? revision shell.

Methods

Regenerex? revision shell is a porous titanium construct optimized for vascularized osteogenesis and designed to accept a cemented all-poly cup. If the bone defects were less than GIR IV or Paprosky type III, the Regenerex? revision shell was consecutively used, and at the end of December 2011, this shell was placed in 33 patients. In this study, we identified 28 cases with a minimum follow-up of 12 months; the mean interval from surgery to evaluation was 25 months; we performed clinical, functional, and radiologic evaluations.

Results

The mean Harris hip score was >83 while the mean Western Ontario and McMaster Universities Osteoarthritis Index score was >75. In five cases, postoperative radiolucent lines were present. No signs of osteolysis were noted around the screws, and none of the 28 cups was thought to be loose.

Conclusions

This preliminary report is to our knowledge the first one to be published about clinical and radiological results on Regenerex? revision shell. Our results are promising, but we need further investigations in order to obtain more data about this material in revision surgery.     

Acetabular cup positioning in revision total hip arthroplasty with Paprosky type III acetabular defects: Martell radiographic analysis

Purpose

This study evaluates acetabular cup position in the setting of revision total hip arthroplasty (THA) with severe acetabular bone defects.

Methods

With a definition of safe zone of abduction (30–50°) and anteversion (5–25°), acetabular cup position was measured by a digital image analysis program for 34 patients with Paprosky type III acetabular bone defects.

Results

There were 24 cups (71 %) for abduction and 26 cups (76 %) for anteversion located in the safe zone. Nineteen cups (56 %) were within the safe zone for both abduction and anteversion. There was no dislocation, however one cup out of the safe zone resulted in early cup failure due to aseptic loosening.

Conclusions

The acetabular cup positioning in patients with Paprosky type III defects was 'optimal' in half of the cases. The prevalence of optimal acetabular cup position was similar to those reported in primary THA, suggesting that the presence of a large acetabular bone defect may not be a significant risk factor for suboptimal acetabular cup positioning in the setting of revision THA.     

High incidence of loosening at 5-year follow-up of a cemented metal-on-metal acetabular component in THR

Introduction

High rates of polyethylene wear in metal-on-polyethylene-bearing surfaces correlate with peri-prosthetic osteolysis and early loosening. Hard-bearing surfaces have been used as they may decrease the production of debris and improve survival of the prosthesis. The aim of this study is to ascertain the rate of early loosening of a polyethylene cemented acetabular component with a metal-on-metal (MOM) insert.

Methods

Between 1997 and 1999, 121 total hip replacements in 114 patients were performed at a single centre by two senior surgeons, using the same prosthesis with a MOM hard-bearing surface of 28 mm diameter. At the mean follow-up of 5 years and 6 months (range 5–7 years), nine patients had died and three were lost to follow-up. We reviewed 107 hips (101 patients). The radiographs and case notes of deceased patients were examined. Follow-up was thus 117 out of 121 hips (96%). Results were evaluated clinically with the Merle d’Aubigne classification, and radiographically with analysis of implant migration and radiolucent lines in the Delee and Charnley areas. The survival rate was calculated.

Results

Six patients (5.6%) had revision surgery for aseptic loosening of the cup: one 2 years after the primary operation, two after 4 years, two after 5 years and one after 6 years. The clinical results according to Postel-Merle d’Aubigne gave 85 excellent results (80%), 10 good results (9.4%) and 6 bad results (5.6%). At the latest follow-up, there were no signs of migration, osteolysis or radiolucent lines involving the femoral component. In the acetabular component, there were five cases of radiolucent lines smaller than 1 mm, which were not progressive. In 24 cases, the radiolucent lines progressed over time and there was a probable failure in 18 cases. The survival rate at 5 years is 94.8% taking revision for any cause as the endpoint and 86.9% taking revision or impending failure (as ascertained by radiographic review) of the cup as the endpoint. Numbers of revisions and radiographic failures were significantly higher with the smaller cups (<48 mm diameter) than the larger (p < 0.05).

Conclusions

This series reports a higher rate of failure with a cemented polyethylene cup with a MOM insert than that reported in the scientific literature for metal-on-polyethylene-bearing surface or MOM uncemented cups. Other similar studies found in the literature are discussed. The authors do not recommend use of this cemented polyethylene-Metasul^® acetabular component.