Surface Arthroplasties Research Articles

Have newer bearing surfaces changed expectations regarding the longevity of total hip arthroplasty?

The purpose of this study is to examine six types of bearing surfaces implanted at a single institution over three decades to determine whether the reasons for revision vary among the groups and how long it takes to identify differences in survival. We considered six cohorts that included a total of 1,707 primary hips done between 1982 and 2010. These included 223 conventional polyethylene sterilized with γ irradiation in air (CPE-GA), 114 conventional polyethylene sterilized with gas plasma (CPE-GP), 116 crosslinked polyethylene (XLPE), 1,083 metal-on-metal (MOM), 90 ceramic-on-ceramic (COC), and 81 surface arthroplasties (SAs). With the exception of the COC, all other groups used cobalt-chromium (CoCr) femoral heads. The mean follow-up was 10 (0.008 to 35) years. Descriptive statistics with revisions per 100 component years (re/100 yr) and survival analysis with revision for any reason as the endpoint were used to compare bearing surfaces. XLPE liners demonstrated a lower cumulative incidence of revision at 15 years compared to the CPE-GA and CPE-GP groups owing to the absence of wear-related revisions (4% for XLPE vs 18%, p = 0.02, and 15%, p = 0.003, respectively). Revisions for adverse local tissue reactions occurred exclusively among the MOM (0.8 re/100 year) and SA groups (0.1 re/100 year). The revision rate for instability was lower among hips with 36 mm and larger head sizes compared to smaller head sizes (0.2% vs 2%, p < 0.001). The introduction of XLPE has eliminated wear-related revisions through 15-year follow-up compared to CPE-GP and CPE-GA. Dislocation incidence has been reduced with the introduction of larger diameter heads but remains a persistent concern. The potential for adverse local tissue reactions with MOM requires continued follow-up. Cite this article: Bone Joint J 2020;102-B(7 Supple B):105-111.

Outcome of Birmingham hip resurfacing at ten years: role of routine whole blood metal ion measurements in screening for pseudotumours.

Emerging concern has arisen because of recent papers reporting a high prevalence of pseudotumours (PTs), even in patients with surface arthroplasties with a good clinical track record. The aim of our study was to establish the ten year survivorship of Birmingham hip resurfacing (BHR), to investigate whole blood (WB) metal ion levels and prevalence of adverse reactions to metal debris (ARMeD) and to determine the association of blood metal ion levels and symptoms with ARMeD in patients operated on with BHR at our institution. Between May 2001 and May 2004, 261 consecutive BHRs were implanted in 219 patients. All living, nonrevised patients underwent a systematic screening programme consisting of clinical examination, WB cobalt and chromium measurements and targeted cross-sectional imaging. The ten year survival for the entire cohort was 91% (89-93%), with any revision as the endpoint. Prevalence of ARMeD was 6.9% in male and 8.8% in female patients. Symptomatic patients with elevated metal ion levels evinced highest prevalence (63%) of PTs compared with asymptomatic patients with elevated metal ion levels (42%) and symptomatic patients with nonelevated metal ions (11%). Contradicting the current international guidelines, our results suggest that it seems beneficial to combine routine metal ion measurement with clinical assessment, even in patients with well-functioning BHRs. Further follow-up will reveal whether new PTs will develop in these patients and BHR survivorship in the longer term.

Results of surface replacement proximal interphalangeal joint arthroplasty

ObjectivesTo evaluate the clinical results and functional outcome measures of surface replacement proximal interphalangeal joint arthroplasty. MethodsProximal interphalangeal joint surface arthroplasties (PIP-SRA) performed by a single surgeon were retrospectively reviewed. Arthroplasties were analysed by radiological and clinical review. Clinical review measured: preoperative and postoperative flexion and extension of the PIPJ; arc of motion; distance to the distal palmar crease (DPC); and Disabilities of the Arm, Shoulder and Hand (DASH) score survey. ResultsForty-eight PIPJ replacements were performed on 24 women and 9 men from 2001 to 2011. Eight patients had more than one joint replacement. The average patient age was 64 years (range 40–84). The average length of follow up was 18 months (range 2–91). The arc of motion improved on average 26° from 55° preoperatively to 81° postoperatively (range 15–150). The average postoperative DPC was 1.8 cm (range 0–8.0) and the average postoperative DASH score 28 (range 1–67). Eleven of the forty-eight joints hyperextended greater than 0° and of these three joints hyperextended greater than 10°. There were four severe flexion contractures. ConclusionsMost patients achieved a functional range of motion and the improvement in arc of motion was excellent. Several patients hyperextended and four had severe flexion contractures. There was a low operation rate but a short follow up makes this difficult to interpret for significance.

Squeaking Hip Arthroplasties: A Tribological Phenomenon

The clinical incidence of squeaking has been reported with increasing frequency, with ceramic-on-ceramic bearings seemingly most affected. This study investigated potential causes of squeaking in hard-on-hard hip bearings through 2 sets of experimental conditions. Bearing clearance appeared to affect the incidence of squeaking in metal-on-metal surface arthroplasties. The addition of third-body particles to the interface for total hip arthroplasties also affected the incidence of squeaking. In both studies, the incidence of squeaking correlated well with elevated friction. The findings of this study suggest that a likely cause of squeaking in the hip arthroplasty is adverse tribological conditions caused by suboptimal lubrication. There are numerous factors that may cause the suboptimal lubrication, and therefore, it is unlikely that an individual cause for squeaking will be identified.

The Relationship between the Presence of Metallosis and Massive Infection in Metal-on-Metal Hip Replacements

With the increased use of metal-on-metal as a bearing surface, complications and side effects are being recognised more frequently. We present a small series of a previously unreported complication, which appears specific to metal-on-metal bearing surface arthroplasties: three cases of infection in the presence of local metal debris and histological features of aseptic lymphocytic vasculitis associated lesions (ALVAL). Each case is associated with significant soft tissue loss and bone destruction to such an extent that pelvic discontinuity has occurred. We postulate that the combination of metal debris, ALVAL and tissue necrosis provides a unique environment for peri-prosthetic bacterial growth and rapid spread of infection.

Hip resurfacing: mid-term results of the last-generation metal-on-metal devices

Total hip resurfacing has long been conceptually attractive to both surgeons and patients. However, historically it has been plagued by limited durability and marked acetabular bone loss. The recent development of wear-resistant bearings such as metal-on-metal has led to renewed interest in hip resurfacing in the orthopaedic community. We report the clinical and radiological results of 350 consecutive surface arthroplasties performed in 325 patients (mean follow-up 20 months). Harris Hip Score increased over time from 57 pre-operatively to 98 at 2 years follow-up. Complication’s rate was low. Four patients required revision surgery. The overall survival rate was 98.8%. Considering the positive results of more than 350 implants of our series, we now believe that there is evidence showing that this surgical concept deserves consideration, particularly when treating young patients with hip diseases.

The John Charnley Award

The reintroduction of surface arthroplasty of the hip with metal-on-metal bearings has the potential to eliminate or substantially reduce long-term wear-induced osteolysis as the major cause of failure. To determine important modes of failure, implant retrieval analysis was done on 98 failed surface arthroplasty components from different manufacturers. Analysis involved sectioning the components, measuring cement mantle thickness and the depth of penetration, histopathology, and measurement of the bearing wear. A finite element model was constructed to examine cement thermal necrosis. Femoral neck fracture and femoral loosening were the main causes of failure. The finite element model showed thermal necrosis could occur when cysts were filled with cement. Histologic observations verified necrosis of interfacial bone, although adaptive remodeling was commonly seen. The amount of cement varied considerably with implant type, and failure mode and was greater in loosened components. Although implant failure is multifactorial, these observations should be a cause for concern in current cementing techniques in which controlling mantle thickness and extent of penetration may be difficult. Optimizing cement technique to avoid leaving the component proud, and to avoid extensive cementation of the femoral head, may be important in reducing some modes of failure. With the application of metal-on-metal bearings, surface arthroplasty is again being performed in a growing number of centers worldwide. Although relatively few procedures have been performed in the United States, thousands of surface arthroplasty components have been implanted in Europe and Australia. We anticipate the problems faced by the first generation of metalpolyethylene surface arthroplasties, primarily related to debris-induced osteolysis caused by polyethylene wear, can be overcome by the current generation of low wearing metal-on-metal surface arthroplasties. Short-term clinical followup reports of metal-on-metal surface arthroplasties have been encouraging, although femoral neck fractures and femoral loosening have been identified as causes of failure. Risk factors in surface arthroplasty highlight the importance of patient selection criteria and good bone quality for implant survival. Currently, the role of femoral head vascularity in implant durability is controversial; some surgeons are concerned the posterior surgical approach sacrifices the important extraosseous blood supply to the femoral head, whereas others believe adequate blood supply will be provided intraosseously. Although the reduced wear of metal-on-metal bearings is well recognized, there have been concerns that heat-treating the components after casting can lead to higher wear, possibly sufficient to cause osteolysis. The unknown long-term consequences of metal wear debris are also a concern. Despite these concerns, the conservative nature of surface arthroplasty and the restoration of a high degree of function, including the ability to return to sports, make this surgery appealing From the Joint Replacement Institute at Orthopaedic Hospital, Los Angeles, CA; UCLA David Geffen School of Medicine, Los Angeles, CA; J. Vernon Luck Research Center at Orthopaedic Hospital, Los Angeles, CA; Division of Orthopedic Surgery/Chirurgie Orthopedique, University of Ottawa, Canada; and ANCA Clinic, Heusden, Belgium. The institution of one or more of the authors (PC, PEB, KDS, HCA) has received funding from Wright Medical Technology; PEB, KDS, HCA are consultants for Wright Medical Technology. One or more of the authors has received funding from the William G. McGowan Charitable Fund (PC, PEB, MLD, HCA), the Orthopaedic Hospital Foundation (PC, PEB, MLD, EE, ZL, HCA) and Wright Medical Technology, USA (PC, PEB, KDS, HCA). Each author certifies that his or her institution has approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained. Correspondence to: Pat Campbell, PhD, Orthopaedic Hospital, 2400 S. Flower Street, Los Angeles, CA 90007. Phone: 213-742-1134; Fax: 213744-1175; E-mail: pcampbell@laoh.ucla.edu. DOI: 10.1097/01.blo.0000238777.34939.82 CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Number 000, pp. 000–000 © 2006 Lippincott Williams & Wilkins

Vascularity of the Arthritic Femoral Head and Hip Resurfacing

With the application of metal-on-metal bearings, hip resurfacing arthroplasty is being performed in a growing number of young adults worldwide. It is anticipated that the problems faced by the first generation of metal-on-polyethylene surface arthroplasties, primarily related to polyethylene wear debris-induced osteolysis1,2, have been overcome by the current generation of low-wearing metal-on-metal surface replacements3,4 (Fig. 1). Short-term clinical followup reports have been encouraging, with a 97% to 99% survival rate at four to five years5-8; however, femoral neck fractures and femoral loosening still pose a challenge5-8. In terms of surgical technique, femoral positioning in a valgus orientation9 and the avoidance of neck notching10 have been advocated. Currently, controversy surrounds the role of femoral head vascularity with regard to implant durability; some surgeons are concerned that the posterior surgical approach sacrifices the important extraosseous blood supply to the femoral head11-13 (Fig. 2), whereas others maintain that an adequate blood supply will be provided intraosseously14. Although femoral head viability may be maintained in part or in whole by an intraosseous blood supply, it is important to critically look at what level of evidence exists to support an intraosseous femoral head blood supply. Some of the evidence comes from retrieval analysis of failed metal-on-polyethylene resurfacing implants15-19 that were associated with a variable prevalence of ischemic failure (see Appendix). This varying prevalence of osteonecrosis-related failures could have been due to the different definitions or varying surgical approaches used as well as the orientation of the specimens during analysis in terms of the differentiation between generalized osteonecrosis and localized necrosis due to cement heat generation20,21. Another reason why these lesions could have been easily missed is …

Metal-on-Metal Hybrid Surface Arthroplasty

Following the reintroduction of metal-on-metal articulating surfaces for total hip arthroplasty in Europe in 1988, we developed a surface arthroplasty prosthetic system using a metal-on-metal articulation. The present study describes the clinical and radiographic results of the first 400 hips treated with metal-on-metal hybrid surface arthroplasties at an average follow-up of three and a half years. Between November 1996 and November 2000, 400 metal-on-metal hybrid surface arthroplasties were performed in 355 patients. All femoral head components were cemented, but only fifty-nine of the short metaphyseal stems were cemented. The patients had an average age of forty-eight years, 73% were men, and 66% had a diagnosis of osteoarthritis. Clinical and radiographic follow-up was performed at three months postoperatively and yearly thereafter. The majority of the patients returned to a high level of activity, including sports, and 54% had activity scores of >7 on the University of California at Los Angeles activity assessment system. Kaplan-Meier survivorship curves demonstrated that the rate of survival of the components at four years was 94.4%. For patients with a surface arthroplasty risk index score of >3, the rate of survival of the components at four years was 89% compared with a rate of 97% for those with a score of <or=3. The patients with a higher risk index were 4.2 times more likely to undergo revision to a total hip replacement at four years. Twelve hips (3%) had a revision to a total hip replacement. Seven of the twelve hips were revised because of loosening of the femoral component, and three were revised because of a femoral neck fracture. Substantial radiolucencies were seen around sixteen uncemented metaphyseal femoral stems. No femoral radiolucencies were observed among the hips in which the metaphyseal stem was cemented. The most important risk factors for femoral component loosening and substantial stem radiolucencies were large femoral head cysts (p = 0.029), patient height (p = 0.032), female gender (p = 0.005), and smaller component size in male patients (p = 0.005). The preliminary experience with this hybrid metal-on-metal bearing is encouraging. Optimal femoral bone preparation and component fixation are critical to improving durability. The metal-on-metal hybrid surface arthroplasty is easily revised to a standard femoral component if necessary.

Metal-on-Metal Hybrid Surface Arthroplasty

BACKGROUND: Following the reintroduction of metal-on-metal articulating surfaces for total hip arthroplasty in Europe in 1988, we developed a surface arthroplasty prosthetic system using a metal-on-metal articulation. The present study describes the clinical and radiographic results of the first 400 hips treated with metal-on-metal hybrid surface arthroplasties at an average follow-up of three and a half years. METHODS: Between November 1996 and November 2000, 400 metal-on-metal hybrid surface arthroplasties were performed in 355 patients. All femoral head components were cemented, but only fifty-nine of the short metaphyseal stems were cemented. The patients had an average age of forty-eight years, 73% were men, and 66% had a diagnosis of osteoarthritis. Clinical and radiographic follow-up was performed at three months postoperatively and yearly thereafter. RESULTS: The majority of the patients returned to a high level of activity, including sports, and 54% had activity scores of >7 on the University of California at Los Angeles activity assessment system. Kaplan-Meier survivorship curves demonstrated that the rate of survival of the components at four years was 94.4%. For patients with a surface arthroplasty risk index score of >3, the rate of survival of the components at four years was 89% compared with a rate of 97% for those with a score of ≤3. The patients with a higher risk index were 4.2 times more likely to undergo revision to a total hip replacement at four years. Twelve hips (3%) had a revision to a total hip replacement. Seven of the twelve hips were revised because of loosening of the femoral component, and three were revised because of a femoral neck fracture. Substantial radiolucencies were seen around sixteen uncemented metaphyseal femoral stems. No femoral radiolucencies were observed among the hips in which the metaphyseal stem was cemented. The most important risk factors for femoral component loosening and substantial stem radiolucencies were large femoral head cysts (p = 0.029), patient height (p = 0.032), female gender (p = 0.005), and smaller component size in male patients (p = 0.005). CONCLUSIONS: The preliminary experience with this hybrid metal-on-metal bearing is encouraging. Optimal femoral bone preparation and component fixation are critical to improving durability. The metal-on-metal hybrid surface arthroplasty is easily revised to a standard femoral component if necessary.

The release of metals from metal-on-metal surface arthroplasty of the hip

The aim of the study was to evaluate the serum and urine levels of cobalt (Co), chromium (Cr), manganese (Mn), molybdenum (Mo) and nickel (Ni) in patients who had undergone metal-on-metal hybrid surface arthroplasties on the supposition that a release of metals would occur due to the large head size of this type of implant. Metal levels were determined by using an analytical method based on sector field inductively coupled plasma mass spectrometry. Results showed a significant difference between patients and control subjects in mean levels of Co and Cr in serum ( p < 0.0 0 0 1 and p = 0.0 2 , respectively) and in urine ( p < 0.0 0 0 1 for both). No significant differences were observed in mean serum and urinary levels of Mn, Mo and Ni. Although the clinical consequences of these changes, if any, are unknown, further studies could be performed in a larger number of subjects implanted with a total surface arthroplasty at follow-up times over different periods.

Metal-on-metal surface arthroplasty with a cemented femoral component: A 7–10 year follow-up study

Forty-two McMinn metal-on-metal surface arthroplasties were implanted in 23 males and 16 females, average age 47.5 years old. The overall survivorship at 7 years was 79%; with any reoperation surgery as endpoint, 80%; and 93%; with aseptic loosening of the socket and femoral component, respectively. The average Surface Arthroplasty Risk Index of patients who had failed or were at risk of failing on the femoral side was significantly greater than for the rest of the cohort, 3.9 versus 1.9. The overall survivorship of the McMinn component was unacceptably low, with the majority of failures occurring with the cemented acetabular components. The recent reintroduction of surface arthroplasty of the hip using metal-on-metal bearings and cementless acetabular components may benefit young patients with hip arthritis with appropriate patient selection.

Orientation of the femoral component in surface arthroplasty of the hip. A biomechanical and clinical analysis.

Although the orientation of the femoral component has been shown to influence the outcome of total hip replacement, its effect on the clinical outcome of surface arthroplasty has not been studied, to our knowledge. The purpose of this study was to examine the relationship between femoral component positioning and the outcome of a surface arthroplasty of the hip. We reviewed the results of ninety-four hybrid metal-on-metal surface arthroplasties in patients who were forty years old or younger at the time of the operation and were followed for a minimum of two years or until the prosthesis failed. Measurements of the hip reconstruction were made on the anteroposterior pelvic radiograph. The correlation between the orientation of the femoral component and the outcome of the arthroplasty was evaluated, as were stresses within the resurfaced femoral head as a function of the orientation of the femoral component. The mean duration of follow-up was 4.2 years. Thirteen hips had an adverse outcome, defined as conversion to a total hip replacement, radiolucency of >1 mm in thickness adjacent to the femoral stem, or narrowing of the femoral neck of >10%. The mean femoral stem-shaft angle in the coronal plane was 138 degrees, with the hips that had an adverse outcome having a significantly lower mean angle than the rest of the cohort (133 degrees compared with 139 degrees, p = 0.03). Hips with an angle of <or=130 degrees had an increase in the relative risk of an adverse outcome by a factor of 6.1 (p < 0.004). In the entire cohort, stresses in the superior aspect of the resurfaced femoral head were substantially lower during slow walking than they were during fast walking (7.1 N/mm(2) compared with 14.2 N/mm(2)). Optimizing the femoral stem-shaft angle toward a valgus orientation during the preparation of the femoral head is important when a hip is being reconstructed with a surface arthroplasty because the resurfaced hip transmits the load through a narrow critical zone in the femoral head-neck region and the valgus angulation may reduce these stresses.

Metal-on-Metal Hybrid Surface Arthroplasty: Two to Six-Year Follow-up Study

Following the reintroduction of metal-on-metal articulating surfaces for total hip arthroplasty in Europe in 1988, we developed a surface arthroplasty prosthetic system using a metal-on-metal articulation. The present study describes the clinical and radiographic results of the first 400 hips treated with metal-on-metal hybrid surface arthroplasties at an average follow-up of three and a half years. Between November 1996 and November 2000, 400 metal-on-metal hybrid surface arthroplasties were performed in 355 patients. All femoral head components were cemented, but only fifty-nine of the short metaphyseal stems were cemented. The patients had an average age of forty-eight years, 73% were men, and 66% had a diagnosis of osteoarthritis. Clinical and radiographic follow-up were performed at three months postoperatively and yearly thereafter. The majority of the patients returned to a high level of activity, including sports, and 54% had activity scores of >7 on the University of California at Los Angeles activity assessment system. Kaplan-Meier survivorship curves demonstrated that the rate of survival of the components at four years was 94.4%. For patients with a surface arthroplasty risk index score of >3, the rate of survival of the components at four years was 89% compared with a rate of 97% for those with a score of </=3. The patients with a higher risk index were 4.2 times more likely to undergo revision to a total hip replacement at four years. Twelve hips (3%) had a revision to a total hip replacement. Seven of the twelve hips were revised because of loosening of the femoral component, and three were revised because of a femoral neck fracture. Substantial radiolucencies were seen around sixteen uncemented metaphyseal femoral stems. No femoral radiolucencies were observed among the hips in which the metaphyseal stem was cemented. The most important risk factors for femoral component loosening and substantial stem radiolucencies were large femoral head cysts (p = 0.029), patient height (p = 0.032), female gender (p = 0.005), and smaller component size in male patients (p = 0.005). The preliminary experience with this hybrid metal-on-metal bearing is encouraging. Optimal femoral bone preparation and component fixation are critical to improving durability. The metal-on-metal hybrid surface arthroplasty is easily revised to a standard femoral component if necessary. Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

Serum and urine metal levels in patients with metal-on-metal surface arthroplasty.

The resurgence of metal-on-metal articulating surfaces for hip arthroplasty has also heightened concerns about the degree and magnitude of metal particle generation and the accompanying increase in circulating metal ion concentrations. In this study, we measured the concentration of chromium in serum and urine and the concentration of cobalt in serum in twenty-five patients with modern metal-on-metal surface arthroplasty of the hip in a prospective manner. The results showed that the mean post-operative chromium in serum levels were 22-fold, 23-fold and 21-fold higher at 3, 6 and 12 months post-operative, respectively, than pre-operative levels. The mean post-operative cobalt in serum levels were 8-fold, 7-fold and 6-fold higher at 3, 6 and 12 months post-operative, respectively, than pre-operative levels. The mean post-operative chromium in urine levels were 9-fold, 10-fold and 14-fold higher at 3, 6 and 12 months post-operative, respectively, than pre-operative levels. The values seen in this study with the current generation of surface arthroplasties are: (a) lower than those seen in an earlier generation of surface arthroplasties; (b) in the same range as those observed in association with metal-on-metal conventional total hip replacements, which typically have smaller head sizes; (c) higher than values observed in patients with conventional metal-on-polyethylene articulating couples.

Uncemented bipolar double-cup arthroplasty of the hip in inflammatory arthropathy

From 1979 to 1986, 42 uncemented surface arthroplasties were performed in 27 patients with an inflammatory arthropathy of the hip: median age at operation 40 years (range 19–65 ys), median follow-up period 73 months (range 36–120 mo). After 36 months, in 26 of 42 hips, the mean Harris Hip Score was excellent or good (mean 89, range 80–100). In 14 cases, the mean score was fair (76, range 70–79). Overall, those hips with the longest followup period (60–120m) gradually improved over the years. No correlation was found between the clinical score and radiologic complications such as varus tilting of the femoral component, acetabular protrusion of the cup, or heterotopic ossification. Conversion to a conventional total hip arthroplasty was required in four patients. One patient required a total hip arthroplasty 86 months after the initial operation because of a femoral neck fracture. In two other patients, revision was performed after 60 and 32 months respectively because of a preexistent osteonecrosis and a severe foreign body response to polyethylene debris. Both patients had a varus tilting of the femoral component. In the fourth patient, in whom revision surgery was necessary 28 months after surface replacement there was no explanation for the varus shift of the femoral component. Regarding those problems that can appear after conventional total hip replacement in inflammatory arthropathy, we conclude that the uncemented surface replacement of the hip can be a reasonable alternative

Early loosening of revision hip arthroplasty: A roentgen stereophotogrammetric analysis

The primary migration of 15 and 22 cemented acetabular and femoral prosthetic components was recorded in 23 patients operated because of type 1 (minimal endosteal bone loss) and type II (thinning of bone, enlargement of femoral canal and acetabulum) mechanical loosening. Roentgen stereophotogrammetric analysis was used to measure the three-dimensional displacements of the center of the acetabulum and the femoral head. All but 1 of the acetabular and 1 of 15 revised femoral stem prostheses migrated within 2 years after the operation, whereas 5 of 7 revised femoral surface arthroplasties were stable. Femoral components with type II loosening migrated, on average, 1.5 mm (range, 0.6–3.0 mm) during the first postoperative year, compared with 0.7 mm (range, 0.3–1.1 mm) in patients with type I loosening ( P < .02). Increased bone loss of the acetabulum (type II), the quality of the bone-cement interface as judged from radiographs, and the presence of perforation of the femoral cortex did not significantly influence the rate of migration in this group. Compared with previously presented studies of cemented primary hip prostheses, cemented revisions seem not only to migrate more frequently but also at a higher rate. Poor primary fixation is probably one important cause of the high frequency of clinical failures in these patients.

Uncemented surface replacement for osteonecrosis of the femoral head

From 1973 to 1982, we performed 40 uncemented surface arthroplasties using 27 Thomine and 13 Gerard cups in 32 patients with osteonecrosis of the femoral head (Ficat Stages 3 and 4). The median follow-up was 8 (3-12) years, with a median age at operation of 35 (19-60) years. Walking ability and mobility were improved, but relief from pain was the most significant improvement. In 28 of the 40 hips the result was excellent or good according to the scoring system of Merle d'Aubigné. The clinical outcome was not influenced by varus angulation, axial resorption, or acetabular protrusion of the cup. As compared with other methods of treatment for osteonecrosis with loss of sphericity of the femoral head, we conclude that the cup arthroplasty is a good choice of treatment in the young patient.