Total hip replacement with a cementless acetabular component and a cemented femoral component in patients younger than fifty years of age

BACKGROUND: We have been using hybrid total hip arthroplasty (a cementless acetabular component and a cemented stem) in young patients. The purpose of this study was to determine the prevalence of aseptic loosening, polyethylene wear, and osteolysis after the use of this technique. METHODS: We studied a prospective consecutive series of sixty-four primary hybrid total hip replacements in fifty-five patients younger than fifty years old. There were forty-three men and twelve women; the average age at the time of the index operation was 43.4 years. The average duration of follow-up was 9.4 years. We used a cementless acetabular component without screw-holes and a cemented femoral component with a 22-mm head in all hips. Clinical follow-up with use of Harris hip ratings and radiographic follow-up were performed at six weeks; at three, six, and twelve months; and yearly thereafter. The sequential annual linear and volumetric wear rates were measured, and bone-remodeling and osteolysis were assessed. RESULTS: The mean preoperative Harris hip score was 44 points, which increased to 95 points at the time of final follow-up. No hip had aseptic loosening. One hip (2%) was revised because of late infection. The average linear wear (and standard deviation) was 0.96 +/- 0.066 mm, with an average annual rate of 0.096 +/- 0.013 mm. The average volumetric wear was 364.7 +/- 25.2 mm (3), with an average annual rate of 43.4 +/- 3.5 mm (3). Six hips (9%) had an osteolytic lesion of <1 cm in diameter in the calcar femorale (zone 7). CONCLUSIONS: Our results show that a hybrid arthroplasty with a cementless acetabular component and a smooth cemented femoral component (Ra, 0.6 mm) is effective for primary total hip replacement in young patients. Although there was no aseptic loosening and a low prevalence of osteolysis at the latest follow-up evaluation, the high rates of linear and volumetric wear of the polyethylene liner in these young patients remain a concern.     

Total hip arthroplasty with a cementless acetabular component and a cemented femoral component in the treatment of Chinese patients with femoral head necrosis

The purpose of this study was to evaluate midterm clinical and radiographic outcomes associated with hybrid total hip arthroplasty in a consecutive series of 86 Chinese patients (93 hips) with osteonecrosis of the femoral head, which revealed that the mean Harris hip score increased from 39 +/- 6.0 points before operation to 90.4 +/- 4.6 points at the latest follow-up. There was pelvic osteolysis in one hip (1%), which required revision, and some small focal areas of femoral osteolysis in 12 hips (13%) were observed. The mean linear wear rate was 0.143 +/- 0.05 mm/y (0.02-0.45 mm/y). No loosening of the components was observed radiographically. The survival rate of the acetabular and femoral components for revision was 98% (95% confidence interval, 0.96-1.0) and 100% (95% confidence interval, 0.95-1.0). Hybrid total hip arthroplasty in patients with osteonecrosis of the femoral head had a satisfactory clinical and radiographic outcome at a minimum 5 years of follow-up. Because polyethylene wear and osteolysis cannot be avoided, the long-term effect should be further studied.     

Developmental hip dysplasia treated with total hip arthroplasty with a straight stem and a threaded cup

BACKGROUND: Operative strategies to overcome the anatomical anomalies in patients with osteoarthritis secondary to developmental dysplasia of the hip remain controversial. The objective of this study was to determine the outcomes of total hip replacement with a grit-blasted cementless threaded cup and a cementless straight stem in patients with developmental dysplasia. METHODS: Ninety-three patients with developmental hip dysplasia who had been treated with a total of 121 cementless total hip arthroplasties were clinically assessed at a mean of 9.3 years. The acetabular reconstruction was done with a cementless threaded cup, which was medialized to ensure that at least one thread was anchored in the bone in order to achieve good primary stability. All radiographs were analyzed retrospectively. RESULTS: Kaplan-Meier survivorship analysis, with radiographic evidence of aseptic loosening as the end point, predicted a survival rate of 97.5% for the acetabular component and 100% for the femoral stem at 9.3 years. The average Harris hip score for the unrevised hips improved from 34.0 points preoperatively to 84.1 points at the latest follow-up evaluation. The average total volume of polyethylene wear at the time of final follow-up was 73.6 mm(3). CONCLUSIONS: These wear and loosening rates demonstrate that very good results were achieved in this relatively young patient population when the hip joint center had been properly restored, even when a small cup with a thin polyethylene liner had been used.     

Polyethylene liner exchange for excessive wear and osteolysis

To determine if polyethylene liner exchange of a total hip arthroplasty decreased wear and slowed the progression of osteolysis, we evaluated 10 hips at a mean 6.2 years after component exchange. Head penetration and lesion size were quantified on serial radiographs using computer-assisted techniques. A mean 7.9 years before component exchange, true polyethylene wear rates averaged 0.36 +/- 0.19 mm/y. A mean 6.2 years after component exchange, average wear rates decreased to 0.17 +/- 0.11 mm/y. Similarly, mean acetabular and mean femoral lesion growth rates decreased. At last follow-up, all components remained radiographically stable. Complications included dislocation (1 patient) and increased wear (2 patients). Modular component exchange with removal of granulomatous tissue has the potential to decrease wear and slow the progression of osteolysis without subsequent component loosening.     

Survival and polyethylene wear of porous-coated acetabular components in patients less than fifty years old: results at nine to fourteen years

BACKGROUND: Younger patients (those who are less than fifty years old) have been shown to have a high rate of failure of cemented acetabular components following total hip arthroplasty. In this report, we present the results associated with the use of an uncemented acetabular component in young patients who were evaluated at a minimum of nine years postoperatively. METHODS: Between December 1984 and December 1989, the senior author performed 174 primary total hip arthroplasties with use of a single design of porous-coated acetabular component. Seventy-one of these procedures were performed in fifty-six patients who were younger than fifty years old. Fifty-six of the seventy-one hips were available for radiographic and clinical analysis after a mean duration of follow-up of eleven years. All hips had been treated with a Harris-Galante-I porous-coated acetabular component that had been placed with a line-to-line fit and fixed with a mean of four screws. Clinical analysis was performed with use of the Harris hip score. Standardized anteroposterior radiographs were analyzed with regard to migration, radiolucent lines, pelvic osteolysis, and two-dimensional linear wear of the polyethylene. RESULTS: No metal shell was revised because of aseptic loosening, and no shell was loose at the time of the latest follow-up. A nonprogressive radiolucent line was seen in one zone in ten hips (18%) and in two zones in six hips (11%). No hip had a radiolucent line in all three zones. Pelvic osteolysis was noted in thirteen hips (23%); the osteolysis was observed in the ischium in eleven hips and around the screws in two. Survivorship analysis revealed that the probability of survival of the metal shell was 98% (95% confidence interval, 96.9% to 99.9%) at ten years. The mean rate of linear polyethylene wear (and standard deviation) was 0.15 +/- 0.10 mm/yr (range, 0.02 to 0.59 mm/yr). The wear rate was significantly increased in patients with an excellent Harris hip score (p = 0.004) and a younger age (less than thirty-eight years) (p = 0.026). With the numbers available, no relationship could be detected between the wear rate and the gender or weight of the patient, the polyethylene thickness, the abduction angle, or the femoral neck length. CONCLUSIONS: The fixation and survival of porous-coated acetabular metal shells in patients less than fifty years old was excellent after a mean duration of follow-up of eleven years. The high rate of linear polyethylene wear and the high prevalence of pelvic osteolysis are of serious concern in this patient population. Continued follow-up will be necessary to evaluate the influence of these findings on the longevity of the fixation of this prosthesis.     

Clinical performance of a Durasul highly cross-linked polyethylene acetabular liner for total hip arthroplasty at five years

BACKGROUND: Highly cross-linked polyethylene is currently the most common articulation surface used for total hip arthroplasty. The hypothesis of the present study was that the Durasul highly cross-linked polyethylene acetabular liner would have less wear at five years than would a conventional polyethylene liner used in association with the same total hip replacement system. METHODS: Forty-three consecutive patients (fifty hips) underwent total hip replacement with an uncemented titanium porous-coated metal cup and a Durasul liner that was mated with a 28-mm cobalt-chromium femoral head. Thirty-one patients (thirty-seven hips) were followed for at least five years. Thirty-five other patients (thirty-seven hips) underwent total hip arthroplasty with the same system but with a conventional polyethylene liner, and these patients also were followed for five years. Clinical assessment was performed with use of the Harris hip score and a patient self-assessment examination. Radiographic analysis included measurements of acetabular component position, fixation, and osteolysis. Femoral head penetration of the Durasul liners was compared with that of the conventional liners. RESULTS: The clinical results as determined on the basis of Harris hip scores and patient self-assessment examinations did not differ between the Durasul group and the control group. The mean bedding-in penetration was 0.054 +/- 0.07 mm for the Durasul group and 0.059 +/- 0.154 mm for the control group. The subsequent penetration, with elimination of the bedding-in wear, resulted in a linear wear rate of 0.029 +/- 0.02 mm per year for the Durasul group, compared with 0.065 +/- 0.03 mm per year for the control group (p < 0.005). The annual penetration at one and five years was 0.074 mm and 0.011 mm, respectively, for the Durasul group, compared with 0.151 mm and 0.04 mm, respectively, for the control group. CONCLUSIONS: While the qualitative wear pattern of the highly cross-linked polyethylene liner was the same as that of the conventional polyethylene liner, the annual linear wear rate was 45% of that seen with the conventional polyethylene liner. Therefore, we believe that these early data support the continued use of this highly cross-linked polyethylene liner for total hip arthroplasty.     

Alumina-on-alumina total hip arthroplasty. A five-year minimum follow-up study

BACKGROUND: Ceramic-on-ceramic couplings are attractive alternative bearing surfaces that have been reported to eliminate or reduce problems related to polyethylene wear debris. Disappointing experiences with alumina ceramic bearings in the past have led to many improvements in the manufacture and design of ceramic implants. The purpose of the present study was to report the results of contemporary alumina-on-alumina total hip arthroplasties with regard to wear, osteolysis, and fracture of the ceramic after a minimum duration of follow-up of five years. METHODS: We evaluated the results of a consecutive series of 100 primary alumina-on-alumina total hip arthroplasties that had been performed with use of a metal-backed socket and a cementless stem in eighty-four patients. All of the patients were sixty-five years of age or younger (mean age, forty-one years), and a single surgeon performed all of the procedures. After a minimum duration of follow-up of sixty months, one patient (one hip) had died and four patients (six hips) had been lost to follow-up, leaving a total of seventy-nine patients (ninety-three hips) available for study. All of these patients were evaluated clinically and radiographically with special attention to wear, periprosthetic osteolysis, and ceramic failure. RESULTS: The mean Harris hip score was 97 points at the time of the latest follow-up evaluation. All prostheses demonstrated radiographic evidence of bone ingrowth. No implant was loose radiographically, and no implant was revised. Ceramic wear was not detectable in the thirty-seven hips in which the femoral head could be differentiated from the cup on radiographs. Periprosthetic osteolysis was not observed in any hip. A fracture of the alumina femoral head and a peripheral chip fracture of the alumina insert occurred in one hip following a motor-vehicle accident. CONCLUSIONS: The results of contemporary alumina-on-alumina total hip arthroplasty with a metal-backed socket and a cementless stem were encouraging after a minimum duration of follow-up of five years. We believe that these improved alumina-on-alumina bearing implants offer a promising option for younger, active patients.     

The Biomet Bi-Metric total hip arthroplasty and universal acetabular cup: high polyethylene failure rate in the medium term

We report on the medium-term results of the Bi-Metric (Biomet UK Ltd, Bridgend, UK) uncemented total hip arthroplasty system used with the Universal acetabular cup and polyethylene liner secured with the Ringloc (Biomet UK Ltd) mechanism. Fifty-eight total hip arthroplasties in 49 patients (mean age at implantation, 57.1 years) were identified, with 45 hips followed up at a mean of 7.6 years (range, 5-13 years). Of those hips not requiring revision, the mean Harris hip score was 89, 87% of the hips were judged to be very good or good according to d'Aubigne and Postel (J Bone and Joint Surgery 1954;36A:451), and the radiographic criteria by Engh et al (Clin Orthop Relat Res 1990;257:107) demonstrated the femoral components to be well fixed. Six patients required a revision procedure at a mean of 6.2 years postsurgery, with all failures attributed to marked wear of the polyethylene liner.     

Mid-term wear characteristics of an uncemented acetabular component

We investigated the rate of polyethylene wear of a cementless acetabular component at different periods of follow-up in order to test the hypothesis than an irrecoverable deformation process (creep) was followed by an initially low, but gradually increasing wear rate. We studied prospectively 93 uncemented total hip arthroplasties in 83 patients (mean age 50 years (22 to 63)) with a mean follow-up of 8.2 years (3 to 12). We measured the penetration of the femoral head from radiographs taken immediately after surgery at three, six and nine years, or at the latest follow-up. The median wear rate was 0.17 mm per year in the first three years, a finding which we considered to be caused by creep. Thereafter, the rate of wear declined to 0.07 mm per year (four- to six-year period) and then increased to 0.17 mm per year (seven to nine years) and 0.27 mm per year (more than nine years), which we considered to be a reflection of genuine polyethylene wear. After the nine-year follow-up the wear rates were higher in patients with marked osteolysis. We found no relationship between the inclination angle of the acetabular component or femoral head orientation and the rate of wear. No acetabular component required revision.     

Ceramic-on-polyethylene bearing surfaces in total hip arthroplasty. Seventeen to twenty-one-year results.

BACKGROUND: Polyethylene wear debris, and the resulting inflammatory response leading to osteolysis and loosening, is the primary mode of failure limiting the longevity of total hip replacements. Alternative bearing surfaces, including ceramic-on-polyethylene, have been investigated in an effort to decrease the amount of polyethylene wear debris. The purpose of this study was to evaluate the seventeen to twenty-one-year results of the use of ceramic-on-polyethylene total hip prostheses. METHODS: Sixty-four total hip prostheses were implanted with cement, by one surgeon, in fifty-six patients from 1978 to 1981. The average age at the index arthroplasty was sixty-nine years (range, fifty-one to eighty-four years). The components consisted of a cemented Charnley-Müller stem with a 32-mm modular alumina femoral head and a cemented all-polyethylene acetabular component. All patients who retained the index prosthesis were assessed clinically with use of Harris hip scores and were evaluated radiographically at the time of the latest follow-up. RESULTS: At the time of this latest follow-up, of the original sixty-four implants, eighteen (28%) were still in place and five (8%) had been revised. The remaining forty-one implants were in patients who had died and were functioning well until the patient's death. No patient was lost to follow-up. Of the eighteen hips with an intact prosthesis in the surviving patients, seven had an excellent clinical result; nine, a good result; and two, a fair result. One asymptomatic hip had definite radiographic evidence of femoral loosening. No hip had definite signs of acetabular loosening or evidence of osteolysis. Survivorship analysis revealed that the probability of survival of the prostheses without revision was 95% at five years, 95% at ten years, 89% at fifteen years, and 79% at twenty years. The mean linear and volumetric polyethylene wear rates were 0.034 mm/yr and 28 mm(3)/yr, respectively. There were no fractures of the ceramic heads. CONCLUSIONS: Outstanding long-term clinical and radiographic results were attained despite the use of what are now considered substandard techniques (an inferior stem design, a 32-mm head, and first-generation cementing techniques). The wear rates in this study are lower than previously reported metal-on-polyethylene wear rates and are consistent with the lowest reported in vivo ceramic-on-polyethylene wear rates. These findings support the consideration of ceramic-on-polyethylene bearing surfaces in total hip arthroplasty.     

Primary Total Hip Arthroplasty With Duraloc Cup in Patients Younger Than 50 Years : A 5- to 7-Year Follow-Up Study

We evaluated the clinical and radiographic results of 67 (64 patients) cementless Duraloc-300 cups for young active patients after a mean follow-up period of 6.2 years. The preoperative mean Harris hip score improved from 46.24 to 96.5 points at 5 years. The survivorship of the cup, using radiographically confirmed aseptic loosening as the end point, was 100% at 5 years. The mean rate of liner wear was 0.125 mm/y (00-0.39 mm/y). Acetabular osteolysis was found in 14% (9 hips) of the 67 hips, and the osteolysis is related to polyethylene wear (P = .0024) and sex (P = .001). Although there was no aseptic loosening of the components, there was a high rate of liner wear of the polyethylene liner and acetabular osteolysis.     

Alumina-on-alumina total hip arthroplasty: a minimum 18.5-year follow-up study.

BACKGROUND: The purpose of this retrospective study was to report the results, after a minimum of 18.5 years of follow-up, in a consecutive series of total hip arthroplasties performed with an alumina-on-alumina combination. METHODS: One hundred and eighteen consecutive total hip arthroplasties were performed in 106 patients between 1979 and 1980. The prostheses combined a 32-mm alumina head and an all-alumina socket. Both components were cemented in eighty-five hips, both components were implanted without cement in twenty-nine, and only the stem was cemented in four. The mean age of the patients at the time of the index arthroplasty was 62.2 years (range, thirty-two to eighty-nine years). RESULTS: At the 18.5 to 20.5-year follow-up evaluation, forty-five patients (fifty-one hips) were alive and had not had a revision, twenty-five patients (twenty-five hips) had undergone revision of one or both components, twenty-seven patients (thirty hips) had died, and nine patients (twelve hips) had been lost to follow-up. The mean Merle d'Aubigné hip score (and standard deviation) was 16.2 +/- 1.8 points at the latest follow-up evaluation. The rate of survival at twenty years, with revision for any reason as the end-point, was 85.6% for the cementless cups compared with 61.2% for the cemented cups and 84.9% for the cementless stems compared with 87.3% for the cemented stems. Wear of the prosthetic components was undetectable on plain radiographs. Periprosthetic cystic or scalloped lesions requiring the use of allograft bone during revision were present in three of the twenty-five revised hips. In addition, seven hips had moderate acetabular osteolysis treated with a 4-mm-larger cup. No fracture of the alumina socket or head was recorded. The mean acetabular wear rate in this series was <0.025 mm/yr. CONCLUSION: With the alumina-on-alumina total hip arthroplasty, minimal wear rates and limited osteolysis can be expected up to twenty years after the operation, provided that sound acetabular component fixation is obtained.     

Results of the anatomic medullary locking total hip arthroplasty at a minimum of twenty years. A concise follow-up of previous reports

Between October 1982 and December 1984, the senior author performed 223 total hip arthroplasties in 215 patients with use of the anatomic medullary locking hip stem and TriSpike cup. We now report on 119 of these hips at a mean of 22.0 years (range, 20.0 to 25.0 years) after surgery. Of the fifty-six hips with minimum twenty-year follow-up radiographs and the original acetabular component, seventeen (30.4%) had pelvic osteolytic lesions measuring larger than 1.5 cm(2). Of the sixty-eight hips with twenty-year radiographs and the original anatomic medullary locking stem, twenty-five (36.8%) had femoral osteolytic lesions measuring larger than 1.5 cm(2). Acetabular osteolysis was significantly associated with cup loosening (p = 0.006), but the presence of femoral osteolysis was not associated with stem loosening. Kaplan-Meier analysis, with revision for any reason as the end point, revealed that the survival rate at twenty years was 85.8% +/- 5.2% for the acetabular shell and 97.8% +/- 2.2% for the stem. The most common reoperation was polyethylene exchange because of wear or osteolysis.     

Total hip arthroplasty in patients with deficient bone stock and small femoral canals

Total hip arthroplasty in patients requiring very small femoral stems is a challenge because frequently deformity and inadequate bone stock, especially of the acetabulum, are also present. An analysis of 34 consecutive cases managed with a 9-mm distal diameter noncemented stem was performed. The mean patient age was 42.6 years and mean follow-up time was 7.8 years. Two patients were lost to follow-up at 4 and 6 years, and 1 patient had a fracture below the stem immediately after surgery, necessitating revision. These patients were excluded from analysis. Of the remaining 31 patients, 1 underwent revision for distal osteolysis leading to fracture. The Harris hip ratings for these patients were 58.1% excellent, 22.6% good, 16.1% fair, and 3.2% poor. Complications experienced included 1 femoral component that fractured but remains asymptomatic. Polyethylene wear of the very small acetabular components in 31% of cases is a cause for concern; 2 of these patients have required revision for this reason. The acetabular component was subsequently modified to allow thicker polyethylene.     

Ten- to twelve-year follow-up of the furlong hydroxyapatite-coated femoral stem and threaded acetabular cup in patients younger than 65 years

We reviewed 82 patients who had 92 primary Furlong uncemented hydroxyapatite (HA)-coated total hip replacements inserted between 1988 and 1992. All patients had the Furlong HA-coated stem and screw in acetabular cup with a 28-mm alumina oxide ceramic modular head. The mean age at the time of primary total hip arthroplasty was 54 years (range, 31-67 years). At 10 years, we reviewed 64 patients (72 total hip arthroplasties). Eight had died (10 total hip arthroplasties), 3 could not attend for follow-up, 2 were lost to follow-up, and 5 were revised (2 for infection and 3 for acetabular loosening and recurrent dislocation). We conclude that the Furlong HA-coated total hip replacement is a good prosthesis for patients younger than 65 years, with a cumulative survival rate of 94.29% at 10 to 12 years using revision as the end point.     

Eight- to ten-year clinical and radiographic outcome of a porous tantalum monoblock acetabular component

In a prospective study, the authors used a porous tantalum monoblock acetabular component for primary total hip arthroplasty between November 1997 and June 1999. A total of 156 consecutive primary total hip arthroplasty were done in 143 patients younger than 75 years. A total of 151 hips had a follow-up time from 8 to 10 years. The average preoperative total Harris hip score of 44.0 ± 13.8 increased to 97.0 ± 6.2 at the latest follow-up. The average preoperative Oxford hip score of 43.3 ± 6.5 improved to 13.9 ± 2.3 at the latest follow-up. Radiographic evaluation including the Ein-Bild-Röntgen-Analyse (EBRA) digital system showed no radiographic evidence of gross polyethylene wear, progressive radiolucencies, osteolytic lesions, acetabular fracture, or component subsidence. There were 7 (4.5%) postoperative complications all unrelated to the acetabular component.     

Cementless cup fixation in total hip arthroplasty after 5–8 years

A series of 199 total hip arthroplasties was performed using a porous-coated, hemispherical press-fit acetabular cup. At a mean follow-up of 91.5 months 158 cups were available for clinical and radiological review. The mean age of the patients at the time of the index arthroplasty was 62.5 years. The mean Harris Hip score at final follow-up was 87.3. No shells were revised although eccentric polyethylene wear prompted liner replacement in two cases. Osteolysis was noted in six cases but predominantly in relation to the femoral stem. Focal pelvic osteolytic lesions were rare. All the cups were classified as stable on radiography.     

Acute total hip arthroplasty for selected displaced acetabular fractures: two to twelve-year results.

BACKGROUND: We assessed the role of acute total hip arthroplasty in a selected group of patients with a displaced acetabular fracture and complicating features that greatly diminished the likelihood of a favorable outcome after open reduction and internal fixation. METHODS: Between 1985 and 1997, fifty-seven patients underwent an acute total hip arthroplasty for a displaced acetabular fracture. Patients were followed for a mean of 8.1 years (range, two to twelve years). The mean time from the injury to the arthroplasty was six days (range, one to twenty days). The mean age of the patients at the time of the arthroplasty was sixty-nine years (range, twenty-six to eighty-nine years). Indications for the acute arthroplasty included intra-articular comminution as well as full-thickness abrasive loss of the articular cartilage, impaction of the femoral head, and impaction of the acetabulum that involved >40% of the joint surface and included the weight-bearing region. RESULTS: At the time of the latest follow-up, the mean Harris hip score was 89 points (range, 69 to 100 points); forty-five patients (79%) had an excellent or good outcome. There were six cases of heterotopic bone formation, including one of symptomatic grade-IV ossification. During the initial six postoperative weeks, the acetabular cups subsided an average of 3 mm medially and 2 mm vertically. All of the cups then stabilized, and none were loose at the latest follow-up evaluation. Six patients had excessive medialization of the cup, but none had late loosening or osteolysis. Nine cups (16%) had notable polyethylene wear, but none were revised. No cup or stem had late clinical or radiographic evidence of loosening. There were three late procedures: one for revision of a malaligned cup because of recurrent dislocations, one for removal of hardware from the greater trochanter, and one for excision of heterotopic bone. CONCLUSIONS: In selected patients with a displaced acetabular fracture that has a low likelihood of a favorable outcome after fracture treatment, an acute total hip arthroplasty may provide an alternative means with which to achieve a painless, mobile hip. These complex procedures are best undertaken by a surgical team with substantial experience with both acetabular trauma and hip arthroplasty.     

The ABG hydroxyapatite-coated hip prosthesis: one hundred consecutive operations with average 6-year follow-up

One hundred consecutive ABG (Anatomique Benoist Giraud, Howmedica) hydroxyapatite-coated hip arthroplasties in 97 patients were evaluated prospectively with a follow-up time of 4 to 10 years (mean, 6 years). Clinical results were excellent with an improvement in the Merle d'Aubigne score from 9 preoperatively to 17.4 at 5 years. Thigh pain was persistent in only 3%; it was mild in nature and controlled with simple analgesics. Kaplan-Meyer survivorship analysis was 100% for the femoral stem and 95% for the acetabular cup at 6 years. Of concern was the high polyethylene wear measured with an average of 0.24 mm/y (range, 0.05-0.76 mm/y).     

Polyethylene wear and osteolysis with a new modular titanium acetabular component: results at 7 to 13 years

The first-generation and second-generation modular titanium fiber-metal acetabular components were notable for high rates of pelvic osteolysis and liner dislodgment. This is a prospective, consecutive study of 111 new modular titanium-fiber metal acetabular components with a novel polyethylene locking mechanism at a mean follow-up of 9.5 years (range, 7-13 years). The polyethylene was gamma-irradiated in air in 58 hips and gamma-irradiated in nitrogen in 54 hips. No acetabular component migrated, none were revised, and there was no liner dislodgment. Pelvic osteolysis was seen in only 2 hips. The mean linear wear rate was 0.085 mm/y (range, 0.001-0.3 mm/y). There was a significantly lower rate of wear with polyethylene liners sterilized by gamma-irradiation in nitrogen (P = .0001). The high rate of success and low rate of polyethylene wear and pelvic osteolysis at this length of follow-up may be related to the new design features of this modular acetabular component.