How prevalent are implant wear and osteolysis, and how has the scope of osteolysis changed since 2000?

Although the incidence of failures resulting from wear-related osteolysis and associated severe bone defects are expected to diminish with important advances in polyethylene manufacturing and processing, alternative bearing surfaces, implant design, and revision techniques, current failures still reflect concerns regarding earlier ultra-high-molecular-weight polyethylene sterilization and degradation. Clinical experience before the year 2000 included rates of wear and osteolysis from 10% to as high as 70% at 7- to 14-year follow-up. With recent advances, early clinical results are encouraging, demonstrating 50% to 81% decreases in radiographic wear rates. These improvements should eventually reduce the burden of future revision hip and knee surgery. However, the long-term in vivo durability of total hip arthroplasties using these alternative materials and bearing couples has not yet been well established, and considerably fewer clinical data are available for other types of joint arthroplasties, such as total knee arthroplasty.     

Ceramic-on-ceramic total hip arthroplasty: A new standard

Total hip arthroplasty (THA) is durable and reliable at relieving pain and improving function in patients with end stage arthritis of the hip joint. Changing patient demographics, risk for aseptic loosening, and instability remain major barriers for long-term implant survivorship. Modern ceramic bearings used in THA have enjoyed good long-term clinical track record and the reliability of these components continues to improve with better materials, surgical technique, and implant design. Coupled with excellent wear characteristics and optimum bearing lubrication with larger head sizes, modern ceramic-on-ceramic THAs can address all of these concerns without the complications of volumetric polyethylene wear associated with the use of large metal ball heads with polyethylene. Consequently, modern ceramics represent the new standard in bearing surfaces for patients undergoing hip replacement surgery.     

Long-Term Follow-Up of Conventional Polyethylene in Total Hip Arthroplasty in Young Patients: Heightened Wear-Related Complications Are Observed at the Beginning of the Third Decade

BackgroundConventional polyethylene (CPE) was used widely in the past as a bearing surface in total hip arthroplasty (THA). As CPE THAs age and the revision burden continues to grow, it is increasingly important to understand the durability and failure mechanisms of this bearing material. Currently, such long-term data remain limited, particularly in younger, more active patients in whom wear issues are of greater concern.MethodsWe retrospectively reviewed 90 hips (77 patients) that underwent primary THA with CPE bearings on cobalt chrome femoral heads at age ≤50 years at 20-year minimum follow-up (mean 21.6 [20-23]). We analyzed polyethylene wear rates, clinical outcomes (modified Harris Hip Score, University of California, Los Angeles Activity Score), and implant survivorship.ResultsWear analysis revealed a median linear wear rate of 0.113 mm/y (95% CI 0.102-0.148) and a median volumetric wear rate of 41.20 mm³/y (95% CI 43.5-61.0). Modified Harris Hip Scores remained 37 points above preoperative baseline (P < .001) and University of California, Los Angeles scores 1.4 points above baseline (P = .018) at 21.6-year mean follow-up. Twenty-nine hips (32.2%) were revised, 20 of which (22.2%) were wear-related at a median of 15.4 years (interquartile range 11.4-19.5). Survivorship free from wear-related revision was 95.6% (95% CI 88.7-98.3), 87.9% (78.6-93.3), 78.1% (49.6-66.5), and 61.1% (41.3-67.0) at 10, 15, 20, and 25 years.ConclusionWear-related issues developed at increasingly high rates after 15 years, suggesting the need for surveillance after this time. The long-term wear and survivorship data of this study may be used as a benchmark when evaluating the performance of contemporary bearings in young, active THA patients.     

Long-term results of cementless anatomic total hip replacement in dysplastic hips

This perspective study analyzes the long-term outcomes of cementless anatomic total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH). Between 1990 and 2004, 100 ABG total hip prosthesis were implanted in 87 patients with DDH. The average follow-up was 9 years (range 4–18 years). The mean Harris Hip Score was 87.13 (SD = 14.6) at the last follow-up. Radiographic analysis showed good results for the stems, while in 38% of the hips we recorded periacetabular bone resorption. Mean linear polyethylene wear was 0.23 mm/year. Ten revisions have been performed, survival rate was 99% for the stems and 90% for the cups. Cementless THA with hemispherical cup and anatomical stem is recommended when possible for patients with DDH although high rates of polyethylene wear and subsequent osteolysis have been the limiting factor in the long-term success of this implant.     

Serial measurement of polyethylene wear of well-fixed cementless metal-backed acetabular component in total hip arthroplasty: an over 10 year follow-up study

Serial radiographic measurements of polyethylene wear were performed in 38 hips (33 patients) with primary cementless total hip arthroplasty (THA). The average follow-up period was 131.8 months. All prostheses were assessed as radiographically stable at the latest follow-up. A two-dimensional method was used to calculate the relative migration of the femoral head center to the cup center. The average total linear wear and wear rate were 1.22 mm and 0.11 mm/year, respectively. The degree of wear in the first 2 postoperative years accounted for nearly 40% of the total wear at the end of the study (average follow up: 131.8 +/- 10.0 months, +/-SD). The migration of the femoral head at an average period of 3. 4 months after operation accounted for 56% of the amount of wear in the first 2 years. Wear rate decreased gradually with time and stabilized after the fourth year. However, in 2 patients, a progressive increase in the wear rate was associated with severe osteolysis and failure of THA. Both creep and wear contributed to the femoral penetration into the polyethylene liner. The influence of creep cannot be ruled out, especially in the early period after operation. Polyethylene wear is a multifactorial process, and the study of individual wear patterns might be useful in identifying patients who are at risk of late failure of THA.     

10-Year Follow-Up Wear Analysis of Marathon Highly Cross-Linked Polyethylene in Primary Total Hip Arthroplasty

Background

Short-term and intermediate-term wear rates for highly cross-linked polyethylene (HCLPE) liners in total hip arthroplasty (THA) are significantly lower than published rates for traditional polyethylene liners. The aim of this study was to report the longest-to-date follow-up of a specific HCLPE liner.

Long-term results of Charnley arthroplasty: A 12–16-year follow-up study

A retrospective, long-term study was initiated to analyze clinical function, failures, and radiographic status in 95 Charnley low-friction arthroplasties performed during 1973–1977. Only patients with primary osteoarthrosis were included, and no patients were lost during the follow-up period. At the follow-up evaluation, 39 patients (41 hips) were deceased. Ten hips were revised (including 3 of the deceased patients), leaving 47 hips available for follow-up evaluation. Four patients (5 hips) were interviewed by telephone, and the remaining 42 hips were examined by the authors. With a mean follow-up period of 14 years, many of the patients had excellent pain relief with a mean Harris hip score for pain of 42 points (maximum, 44 points). Ninety-four percent of the patients were satisfied with their results. The survivorship for all 95 hips was 92% at 10 years and 83% at 16 years. Follow-up radiographs revealed that three (7%) of the femoral components were definitively loose, but only two (5%) of the acetabular components were probably loose. Forty-three percent of the hips had signs of polyethylene wear of the cup. The clinical and radiographic outcome is, in spite of an early cementing technique, very good in this long-term follow-up study.     

Wear of highly crosslinked polyethylene acetabular components

Background and purpose — Wear rates of highly crosslinked polyethylene (XLPE) acetabular components have varied considerably between different published studies. This variation is in part due to the different techniques used to measure wear and to the errors inherent in measuring the relatively low amounts of wear in XLPE bearings. We undertook a scoping review of studies that have examined the in vivo wear of XLPE acetabular components using the most sensitive method available, radiostereometric analysis (RSA).

Methods — A systematic search of the PubMed, Scopus, and Cochrane databases was performed to identify published studies in which RSA was used to measure wear of XLPE components in primary total hip arthroplasty (THA).

Results — 18 publications examined 12 primary THA cohorts, comprising only 260 THAs at 2–10 years of follow-up. The mean or median proximal wear rate reported ranged from 0.00 to 0.06 mm/year. However, differences in the manner in which wear was determined made it difficult to compare some studies. Furthermore, differences in RSA methodology between studies, such as the use of supine or standing radiographs and the use of beaded or unbeaded reference segments, may limit future meta-analyses examining the effect of patient and implant variables on wear rates.

Interpretation — This scoping review confirmed the low wear rates of XLPE in THA, as measured by RSA. We make recommendations to enhance the standardization of reporting of RSA wear results, which will facilitate early identification of poorly performing implants and enable a better understanding of the effects of surgical and patient factors on wear.     

14-year follow-up study of a patient with massive calcar resorption. A case report

The authors present an in-depth clinical, radiographic, and pathologic analysis of a 62-year-old man with massive bone reabsorption around the proximal femur in a total hip arthroplasty (THA). The THA was revised 13 years after implantation. Thirty millimeters of calcar resorption was noted radiographically. Evidence of stem bending was present on examination of the femoral implant, and marked wear of the acetabular cup was noted. The pathologic evaluation of removed calcar bone and cement revealed a histiocytic mass invading the bone. Intracellular and extracellular polymethylene debris was noted within the invasive mass. Evidence of fragmented methylmethacrylate cement was also present. The bone-cement interface in the excised calcar region contained segments that showed active bone remodelling around the cement without an interposed membrane. It is possible that this case of calcar resorption began with histiocytic activation and recruitment by polyethylene wear debris followed by active bone lysis. The process may be perpetuated by the fragmentation of cement, as motion occurred at the calcar bone-cement interface, and may represent an extreme example of a process occurring in cases of calcar resorption in general.     

Cementless THA for the Treatment of Osteonecrosis at 10-Year Follow-Up: Have We Improved Compared to Cemented THA?

Results of cementless THA for osteonecrosis were evaluated at a minimum of 10-year follow-up and compared to our previous report of cemented THA for osteonecrosis. Eighty cementless THAs in 66 patients with osteonecrosis were followed for a minimum of 10 years. Evaluation consisted of need for revision; radiographic evidence of loosening, wear and osteolysis; activity monitoring with an accelerometer; UCLA, Tegner, WOMAC, and Harris hip scores. Results were compared to 48 cemented THAs performed for osteonecrosis with comparable follow-up. At a minimum of 10 years, 10 hips required reoperation. Loosening and revision for loosening were significantly lower in the cementless group compared to the cemented historical control. Cementless fixation in THAs for osteonecrosis demonstrated durable results with bearing surface wear being the major long-term problem.     

Ten- to 15-Year Clinical and Radiographic Results for a Compression Molded Monoblock Elliptical Acetabular Component

The aim of this study was to report the long-term results from a previously published midterm follow-up of a titanium monoblock, elliptical acetabular component. A total of 258 primary total hip arthroplasties (212 patients) with a monoblock, acetabular component were followed up for a mean period of 11.1 years (10-15). Average yearly wear rate was 0.08 mm/y (0.0009-0.32). Acetabular radiolucencies were present in 6 hips (2.4%); all were nonprogressive and present in acetabular zone I. Acetabular osteolysis was present in 5 patients (5 hips, 1.9%); all cups were stable. Four acetabular components were revised, 3 because of recurrent instability. No acetabular components were revised for polyethylene wear or dissociation, acetabular osteolysis, loosening, or deep infection. This monoblock design demonstrates excellent long-term survival and low rate of osteolysis.     

Unexpected Wear of a Uniquely Designed Moderately Cross-Linked Polyethylene in Total Hip Arthroplasty

BackgroundA uniquely designed, non–heat-treated moderately cross-linked acetabular polyethylene liner used in total hip arthroplasty (THA) demonstrated excessive wear during routine follow-up, prompting an evaluation of the linear wear rate.MethodsAll THAs were performed by the senior author. The study group included 38 THAs using the uniquely designed polyethylene in question, compared to a control group of 21 THAs using another moderately cross-linked polyethylene with good 10-year outcomes. Two-dimensional linear head penetration wear measurements were obtained using the Martell Hip Analysis Suite, and retrieval analysis was performed on two liners.ResultsThe study group had a significantly higher average penetration rate of 0.089 mm/y than the control group average rate of 0.047 mm/y (P = .04). Forty-five percent of the study group had a wear rate above the osteolysis threshold (0.1 mm/y), compared to 24% in the control group. Macroscopic analysis of two retrieved liners validated the radiographic findings.ConclusionThe data suggest unexpectedly higher wear rates for a moderately cross-linked polyethylene design, with nearly half of the study group at risk for osteolysis. Further registry or database analyses of this particular moderately cross-linked polyethylene are warranted.     

Ceramic-on-ceramic total hip arthroplasty: A new standard—Affirms

Highly cross-linked polyethylene has emerged as an improvement over conventional polyethylene in terms of wear characteristics and osteolysis in total hip replacement; however, decreased material properties could make it unsuitable for use in high-demand patients. Modern ceramic-on-ceramic bearings display extremely low wear and durability that make them an ideal bearing surface. Unfortunately, certain implant designs have been associated with squeaking, which has discouraged widespread use. Proper implant selection, orientation, and surgical technique can lead to optimal results with ceramic bearings, and substantial mid- to long-term data exists to support their use over other bearing surfaces in total hip replacement.     

How are wear-related problems diagnosed and what forms of surveillance are necessary?

Prospective, randomized clinical wear studies have shown significant wear reduction when highly cross-linked, e-beamed, melted polyethylene was compared with conventional polyethylene sterilized by gamma irradiation in air. More complete assessment of wear-induced osteolysis in the general total hip arthroplasty patient population must rely on registries with follow-up of large populations of patients through radiographic evaluation of wear-related factors, such as suboptimal placement of the implant components, osteolytic defects, and aseptic loosening. Follow-up radiographs should be obtained in the early postoperative period and at 1, 5, and 10 years postoperatively, and then every 1 to 5 years, thereafter depending on radiographic findings of osteolysis and its progression. When pathologic findings are present, further examinations, such as oblique Judet views and magnetic resonance imaging (MRI) with artifact minimization should be considered to provide a better determination of the extent of the osteolysis. Because conventional radiographs underestimate the prevalence and extent of osteolysis in many instances, diagnosis and surveillance should be performed with radiographic edge detection, spiral computed tomography (CT), MRI, radiostereometric analysis, and quantitation of wear and osteolysis, including bone and soft-tissue lesions. Helical CT has demonstrated excellent specificity in identifying and quantifying the extent of osteolysis. MRI can more accurately localize both osseous and soft-tissue particulate disease, and detect granuloma and compression on adjacent nerves and vessels.     

Results of cemented metal-backed acetabular components: A 10-year-average follow-up study

The clinical and radiographic results of 86 primary total hip arthroplasties performed in 74 patients from 1983 to 1987 with a cemented metal-backed acetabular component and a cemented collared straight femoral stem with a 32-mm head were reviewed at a mean follow-up of 10.1 years. Seven patients (9.2%) underwent acetabular component revision at a mean of 9.0 years after implantation; an additional 24 components (31.6%) demonstrated evidence of radiographic loosening, resulting in a total failure rate of 40.8%. Periacetabular radiolucencies were noted in Charnley zones at the following rates: 34.2% in zone I, 18.4% in zone II, and 27.6% in zone III. In addition, 18.4% and 38.2% of implants demonstrated evidence of migration and excessive polyethylene wear. Excessively vertical cup placement (>49° inclination) at the time of initial arthroplasty was statistically correlated with polyethylene wear, implant migration, and fixation failure. A trend of increasing implant failure was also noted with decreasing polyethylene liner thickness. Periacetabular cement mantle thickness was not statistically correlated with subsequent component loosening or failure. Results of Kaplan-Meier survivorship analysis using revision as an endpoint showed 93.6% survivorship at 10 years and 88.4% at 12 years. The mean modified Harris hip scores were 46.9 preoperatively and 81.8 at final follow-up. The significant overall rates of radiographic loosening, migration, polyethylene wear, and implant revision confirm the suspected trend of increasing failure rates of cemented metal-backed acetabular components over time.     

Conventional Polyethylene in Total Hip Arthroplasty in Young Patients: Survivorship,Wear Analysis,and Clinical Outcomes Between 15 and 20 Years

Background

Total hip arthroplasty (THA) remains a successful procedure for most patients. However, there is a paucity of information regarding the long-term performance of conventional polyethylene (CPE) bearings in young patients undergoing THA.

Hydroxyapatite-coated stems with metaphyseal and diaphyseal press-fit. Eleven-year follow-up results

We report the 11-year follow-up results of 52 unilateral primary hip arthroplasties performed with hydroxyapatite-coated stems. The femoral prosthesis used was a collarless titanium alloy implant, with proximal circumferential hydroxyapatite coating and increased distal thickness to fit the proximal diaphyseal region of the femur. Clinical evaluation was performed using the Merle d'Aubigné Hip Score. Anteroposterior and lateral radiographs were obtained and compared with previous postoperative films. Radiographic evaluation was carried out following Engh's criteria for uncemented implant fixation and using Livermore's method for measurement of polyethylene wear. At the end of the follow-up period, excellent and good clinical results were recorded in 40 arthroplasties (77%). The incidence of thigh pain at one year was 32.7%, but it decreased to 4.2% after the first post-operative year. The 11-year survival rate was 92.3%. Seven arthroplasties were revised because of aseptic loosening of the cup in one case, aseptic loosening of the stem, in one case, septic loosening of the stem in one case, periprosthetic fracture in two cases and polyethylene wear in three cases. Forty-two (87.5%) of the nonrevised stems met the criteria for radiographic osseointegration. Cortical hypertrophy was observed around the mid-part and tip of the stem in 22 patients of the series. This sign tends to be related to thigh pain (p < 0.1). Calcar osteolysis was present in 8 cases. There was only one case of distal femoral osteolysis. We found a strong and significant relationship between long-term wear rates and the occurrence of osteolysis (p < 0.001). We concluded that thigh pain is in relation to the distal diameter of the stems and significantly decreases after the first postoperative year. There was a low incidence of osteolysis in our series in comparison with other series of noncemented implants with 32-mm femoral heads and with similar follow-up.     

The Harris-Galante cementless THA: a 19- to 25-year follow-up study

The goal of this study was to evaluate the long-term survivorship of primary cementless total hip arthroplasty (THA) using Harris-Galante porous I acetabular and Harris-Galante porous femoral components. From July 1985 to December 1991, we performed primary cementless THA on 76 hips (70 patients). Twenty-nine patients (31 hips) died due to causes unrelated to the THA, and 6 patients (7 hips) were lost to follow-up. Of 76 hips (70 patients) studied, 38 hips (35 patients) were available for follow-up at a mean 22.5 years (range, 19-25 years) postoperatively. Mean patient age at index procedure was 51.2 years (range, 42-65 years). Average Harris Hip Score was 40.5 points preoperatively and 85.8 points at final follow-up. No patient had an early or late postoperative deep infection. Radiographically, the acetabular component fixation was stable in all 38 hips. The femoral component was bone-ingrown in 26 hips, stable-fibrous in 10, and unstable in 2. One unstable hip required revision of the femoral component. Dissociation of the polyethylene liner occurred in 3 hips without fractures of the metal locking tines and required revision of the polyethylene liner and the articular head. A total of 4 hips had documented revision, and 1 femoral component failed radiographically. The survival rate with the endpoint defined as revision surgery and radiographic loosening was 86.8% at 22.5 years of follow-up. Mean polyethylene wear was 0.085 mm/year (range, 0.031-0.15 mm). This study found that the Harris-Galante porous I acetabular and Harris-Galante porous femoral components produce excellent long-term results.     

Up to 18-Year Follow-Up Wear Analysis of a First-Generation Highly Cross-Linked Polyethylene in Primary Total Hip Arthroplasty

Background

The advent of highly cross-linked polyethylene (HCLPE) has significantly improved total hip arthroplasty survivorship. HCLPE has been shown to improve wear properties in midterm outcomes when compared to traditional polyethylene liners; however, there is a paucity of studies evaluating long-term outcomes. In addition, there is concern that wear rates may accelerate as the implant ages. Thus, the aims of this study are to report on the longest-to-date follow-up of a specific first-generation HCLPE liner and to determine whether there is a change in the annual wear rate over time.

Early outcomes of sequentially cross-linked thin polyethylene liners with large diameter femoral heads in total hip arthroplasty

Two important issues affecting the outcome of total hip arthroplasty have been dislocation and wear, despite excellent clinical results. Larger femoral heads have had success in decreasing dislocation rates; however, there are concerns regarding the subsequent use of thinner polyethylene liners, and their effects on wear rates. Historically, high stresses on thin polyethylene bearings have caused concerns, including rim cracking and catastrophic implant failure with polyethylene thicknesses less than 5 millimeters. Recently, sequentially cross-linked and annealed polyethylene has been shown to reduce the wear rate significantly, compared to conventional ultra-high-molecular-weight polyethylene (UHMWPE) in vitro. The purpose of this study was to analyze the clinical and radiographic outcomes in a cohort of patients treated with sequentially cross-linked and annealed polyethylene bearings with a nominal thickness of 3.8 millimeters. Outcomes were compared to a similar cohort of patients who were treated with total hip arthroplasty during the same time period and utilizing the same polyethylene thickness of 5.8 millimeters or greater. MATERIALS AND METHODS: We identified 50 patients (53 hips) who had a minimum 2-year clinical and radiographic follow-up after a standard total hip arthroplasty, performed with a thin, sequentially cross-linked and annealed polyethylene bearing surface. There were 15 males and 35 females, with a a mean age of 60 years (range, 16 to 93 years) and a mean body mass index of 28.6 kg/m2 (range, 17.2 to 47.5 kg/m2). Overall survivorship was compared to a cohort of 50 patients (53 hips) treated with total hip arthroplasty during the same time period, utilizing the same polyethylene of 5.8 millimeters or greater thickness. Radiographic analysis of polyethylene wear was performed on a subset of 26 hips, using a previously validated two-dimensional computer-aided technique. Volumetric wear was calculated and subsequent annual volumetric and linear wear rates were derived for each patient in the study cohort. Additionally, radiographic analysis was performed to assess for any progressive radio-lucencies or malalignment. RESULTS: The overall survivorship of the study cohort was 100%, compared to a 96% survivorship in the comparison group (two failures due to infection). The mean Harris hip scores in the thin polyethylene cohort improved from 43 points (range, 10 to 67 points) pre-operatively to 91 points (range, 69 to 100 points) postoperatively. Upon radiographic review, no malalignment, radiolucencies, or polyethylene fracture was noted in the study cohort. The mean volumetric wear rate was 0.4122 mm3/year (range, 0.2311 to 0.7310 mm3/year), and the mean linear wear rate was 0.0004 mm/year (range, 0.0002 to 0.0007 mm/year) for the thin polyethylene group. The mean volumetric wear was 0.8839 mm3 (range, 0.4621 to 1.5839 mm3) for this cohort. Excellent clinical and radiographic outcomes were found for patients treated with thin, sequentially cross-linked and annealed polyethylene bearings utilized in total hip arthroplasty, with a nominal thickness of 3.8 millimeters. We have not seen any failures with thin polyethylene liners that have undergone this manufacturing process, which is in contradistinction to results of previously reported thin polyethylene liners. Wear rates were lower than other bearing surfaces at similar periods.