Low Wear Rates Seen in THAs With Highly Crosslinked Polyethylene at 9 to 14 Years in Patients Younger Than Age 50 Years

Background

Patients 50 years or younger are at high risk for wear-related complications of their total hip arthroplasty (THA) because of their generally higher levels of activity. Highly crosslinked polyethylene (HXLPE) is believed to be more durable for this population than conventional polyethylene because of its improved wear; however, limited information is available on the wear of HXLPE in this population, particularly the wear of HXLPE when it articulates with alternative bearings like Oxinium (Smith & Nephew, Memphis, TN, USA).

Questions/purposes

The purpose of this study was to evaluate two questions relative to this population of patients undergoing THA. First, what was the linear and volumetric wear rate of HXLPE in patients 50 years or younger at a minimum followup of 9 years and was osteolysis observed in any of these hips? Given the potential for damage to the Oxinium femoral head surface, was the wear of HXLPE in the patients with this material similar to the other bearings or was there accelerated or runaway wear that was visible in any of the patients?

Methods

From November 1999 to April 2005, 105 THAs were performed in 95 patients 50 years of age or younger (mean, 42 years; range, 20–50 years). The mean body mass index was 30 kg/m² (range, 17–51 kg/m²).The mean followup was 12 years (range, 9–14 years). Two patients died, five patients (one bilateral) were lost to followup, and one hip was revised elsewhere for pain. The patients’ information was not included in the study, which left 87 patients with 96 hips for analysis. Highly crosslinked polyethylene was the acetabular bearing for all of the hips. We analyzed the linear and volumetric wear of all of the hips using the Martell method. Eighty hips had the same diameter head (28 mm) allowing us to more accurately compare the different bearing materials. The type of femoral head used was related to our sequential use of materials beginning with cobalt chrome (14), ceramic (23) followed by Oxinium (43) in the hips with 28-mm heads. Although cobalt-chrome was used early in this study, our previous experience with ceramic on polyethylene encouraged us to use it as an alternative bearing. The Oxinium was used consecutively for the remaining hips.

Results

The mean wear of the HXLPE after 1 year of bedding-in (true linear wear)was 0.022 mm/year (95% confidence interval [CI], 0.015–0.030 mm/year). The mean volumetric wear of HXLPE after 1 year of bedding-in (true volumetric wear) was 9 mm³/year (95% CI, 4–14 mm³/year). None of the hip radiographs had evidence of loosening or osteolysis. Wear was not associated with femoral head material (p = 0.58 for linear wear/year versus head material and p = 0.52 for volumetric wear/year versus head material).

Conclusions

In our study of patients 50 years of age or younger undergoing THA, the linear and volumetric wear rates of HXLPE were very low regardless of the bearing surface material. The laboratory concerns of Oxinium surface damage are serious but at this time we have not seen high wear of the HXLPE or osteolysis in this population.

Level of Evidence

Level III, therapeutic study.     

Effect of femoral head size on polyethylene wear and synovitis after total hip arthroplasty: A sonographic and radiographic study of 39 patients

Background and purpose?The role of synovitis and high fluid pressure in the loosening process after total hip arthroplasty has gained increasing attention. We investigated the correlation between head size, polyethylene wear, and capsular distention.

Patients and methods?We analyzed 39 unrevised, radiographically stable hips that had been operated with 28 or 32 mm femoral heads 10 years earlier because of osteoarthritis. We evaluated radiographic signs of loosening, linear and volumetric polyethylene wear, body mass index, activity level, and age. Sonographic examination was performed to measure capsular distance i.e. the distance between the prosthetic femoral neck and the anterior capsule.

Results?Linear wear was 0.09 mm/year and 0.18 mm/year in the 28 mm and 32 mm groups, respectively (p < 0.001). The volumetric wear was 51 mm³/year and 136 mm³/year (p < 0.001) and the capsular distance was 13 mm and 17 mm, respectively (p < 0.001). There was a correlation between linear wear (r = 0.54), volumetric wear (r = 0.62), and capsular distance (p < 0.001).

Interpretation?Wear was greater for the larger femoral head and was correlated to capsular distension.     

Short-term wear of Japanese highly cross-linked polyethylene in cementless THA

INTRODUCTION: Production of polyethylene wear from acetabular liners is thought, in part, to mediate the periprosthetic osteolysis. This study examined the in vivo wear performance of Japanese highly cross-linked polyethylene (Aeonian) in cementless total hip arthroplasty. MATHERIALS AND METHODS: Ninety-five hips received a highly cross-linked polyethylene liner, while 20 hips were implanted with conventional polyethylene. Two-dimensional linear wear was measured on radiographs and volumetric wear was then calculated. Both linear and volumetric wear rates were examined for the 1-year postoperative period as well as for the time frame beginning after 1 year ending with the final follow-up. RESULTS: The amount of linear wear was significantly lower in the cross-linked group at 3 and 5 years postoperatively (P < 0.01 and < 0.001, respectively). Linear and volumetric wear rates after 1 year postoperatively for hips with the cross-linked polyethylene were significantly reduced by 57 and 59%, respectively, when compared to rates for those who received conventional polyethylene (P < 0.01). A multiple logistic regression analysis revealed that cross-linking was a significant factor influencing linear wear rate after 1 year postoperatively with an odds ratio, exp(ss) = 10.033 (P < 0.001). CONCLUSION: These results suggest that the highly cross-linked polyethylene reduces penetration of the femoral head and may be an optimal bearing surface for patients receiving total hip arthroplasty.     

Oxidized Zirconium Head on Crosslinked Polyethylene Liner in Total Hip Arthroplasty: A 7- to 12-year In Vivo Comparative Wear Study

Background

Osteolysis resulting from wear debris production from the bearing surfaces is a major factor limiting long-term survival of hip implants. Oxidized zirconium head on crosslinked polyethylene (XLPE) is a modern bearing coupling. However, midterm in vivo wear data of this coupling are not known.

Questions/purposes

The purpose of this study was to investigate in vivo whether the combination of an oxidized zirconium femoral head on XLPE produces less wear than a ceramic head on XLPE or a ceramic head on conventional polyethylene (CPE) couplings and whether any of these bearing combinations results in higher hip scores.

Methods

Between 2003 and 2007, we performed 356 total hip arthroplasties in 288 patients; of those, 199 (69.1%) patients (199 hips) were enrolled in what began as a randomized trial. Unfortunately, after the 57^th patient, the randomization process was halted because of patients’ preference for the oxidized zirconium bearing instead of the ceramic after (as they were informed by the consent form), and after that, alternate allocation to the study groups was performed. Hips were allocated into four groups: in Group A, a 28-mm ceramic head on CPE was used; in Group B, a 28-mm ceramic head on XLPE; in Group C, a 28-mm Oxinium head on XLPE; and in Group D, a 32-mm Oxinium head on XLPE. The authors prospectively collected in vivo wear data (linear wear, linear wear rate, volumetric wear, and volumetric wear rate) using PolyWare software. Preoperative and postoperative clinical data, including Harris and Oxford hip scores, were also collected at regular intervals. Of those patients enrolled, 188 (95%) were available for final followup at a minimum of 7 years (mean, 9 years; range, 7–12 years).

Results

All bearing surfaces showed a varying high bedding-in effect (plastic deformation of the liner) up to the second postoperative year. At 5 years both oxidized zirconium on XLPE groups showed lower (p < 0.01) volumetric wear (mean ± SD mm³) and volumetric wear rates (mean ± SD mm³/year) (Group C: 310 ± 55–206 ± 55 mm³/year, Group D: 320 ± 58–205 ± 61 mm³/year) when compared with ceramic on CPE (Group A: 791 ± 124–306 ± 85 mm³/year) and ceramic on XLPE (Group B: 1420 ± 223–366 ± 88 mm³/year) groups. For those patients who had completed 10 years of followup (20 patients [44.5%] of Group A, 21 [45.7%] of Group B, 23 [47.9%] of Group C, and 22 [44.9%] of Group D), at 10 years, both oxidized zirconium on XLPE groups also showed lower (p < 0.01) volumetric wear (mean ± SD mm³) and volumetric wear rates (mean ± SD mm³/year) (Group C: 356 ± 64 to 215 ± 54 mm³/year, Group D: 354 ± 50 to 210 ± 64 mm³/year) when compared with ceramic on CPE (Group A: 895 ± 131 to 380 ± 80 mm³/year) and ceramic on XLPE (Group B: 1625 ± 253 to 480 ± 101 mm³/year) groups. When wear rates of both oxidized zirconium groups were compared, no differences were found at any time interval with the numbers available. Two hips (one from Group A and one from Group B) are scheduled for revision as a result of wear and osteolysis. There were no differences in hip scores among the groups with the numbers available.

Conclusions

In this study, in vivo wear parameters were lower when the combination of an oxidized zirconium head on XLPE liner was used at an average of 9 years (range, 7–12 years) followup. Further larger-scale clinical studies should confirm these findings and evaluate osteolysis and revision rates in association with the use of this bearing coupling.

Level of Evidence

Level II, therapeutic study.     

Large Metal Heads and Highly Cross-Linked Polyethylene Provide Low Wear and Complications at 5-13 Years

Background

Highly cross-linked polyethylene (XLPE) is reported to have low rates of linear and volumetric wear at 10-14 years. In a prior study, larger (36 and 40 mm) femoral heads were associated with more volumetric wear, but there were only 12 hips with these heads.

Three-dimensional polyethylene wear of a press-fit titanium prosthesis: Factors influencing generation of polyethylene debris

Between 1985 and 1990, 108 consecutive Harris-Galante I (Zimmer, Warsaw, IN) total hip arthroplasties were performed by four surgeons at a single hospital. At the time of follow-up evaluation, 80 hips were available for review. The mean rate of linear wear was 0.15 mm/y, mean rate of three-dimensional femoral head displacement was 0.21 mm/y, and mean rate of volumetric wear was 121 mm³/y. Eight hips (10%) in this series had radiologic osteolysis around either the femoral or acetabular component. A significantly greater volumetric wear rate was found in patients who were younger, those with a higher activity level, those who received a 32-mm-diameter femoral head, and those with vertical orientation of their acetabular component. No relationship could be made with patient weight, gender, Harris hip score, or cup diameter.     

Short-term in vivo wear of cross-linked polyethylene

BACKGROUND: Cross-linked polyethylene was developed to reduce volumetric wear in prosthetic joints. Hip simulator studies have shown promising results with regard to wear reduction. This study evaluated the short-term in vivo wear of a moderately cross-linked polyethylene. METHODS: Linear head penetration, as an assessment of in vivo polyethylene wear, was measured in two groups of patients after total hip replacement. Twenty-four hips received a conventional polyethylene insert and thirty-four, a cross-linked polyethylene liner; both inserts were manufactured by the same company. Linear and volumetric wear rates were measured on radiographs with use of a validated computer-assisted technique and were adjusted for patient-related factors. Patient activity was assessed by a computerized two-dimensional accelerometer worn on the ankle. RESULTS: Patients with a conventional polyethylene insert showed a mean linear wear rate of 0.13 mm per year and a mean volumetric wear rate of 87.6 mm(3) per year. The group with a cross-linked polyethylene liner showed a mean linear wear rate of 0.02 mm per year and a mean volumetric wear rate of 17.0 mm(3) per year. Wear in the group with cross-linked polyethylene was 81% lower than that in the group with conventional polyethylene (p < 0.00001). Accounting for differences in patient activity, the adjusted wear rates per million cycles for a patient weight of 70 kg were 53 mm(3) per million cycles for conventional polyethylene and 15 mm(3) per million cycles for cross-linked polyethylene, a 72% reduction (p = 0.0002). No factor, other than the type of polyethylene, was found to influence the difference in wear rates between the two groups. CONCLUSIONS: The results of this study are promising. The in vivo wear reduction with this cross-linked polyethylene is consistent with the predictions of hip simulator studies.     

Similar Wear in Total Hip Arthroplasties with Metallic or Zirconia Femoral Heads

Ceramic femoral heads have been used in an attempt at reducing polyethylene wear of total hip arthroplasties. Clinical results with zirconia femoral heads have been mixed. This study was undertaken to compare the polyethylene wear and incidence of periprosthetic osteolysis in total hip replacements performed using a 28-mm zirconia versus a 28-mm cobalt chromium femoral head. Thirty-five hips with a 28-mm cobalt chromium head and 68 hips with a 28-mm zirconia head were evaluated after a minimum follow-up of 2 years (average, 4.0 years; range, 2.0 to 9.1 years). A monoblock acetabular component was used in all patients. Polyethylene wear was measured in serial radiographs from 58 of the hips utilizing a computer-assisted vector wear technique. Periacetabular osteolysis developed in three patients (two with a zirconia head and one with a cobalt chromium head). The total wear and the annual wear rate were 0.48 mm and 0.11 mm/year for the cobalt chromium heads and 0.53 mm and 0.14 mm/year for the zirconia heads, respectively. We found no benefit with respect to the rate of polyethylene wear or incidence of osteolysis with the use of zirconia femoral heads.     

Fifteen-Year to Twenty-Year Results of Cementless Harris-Galante Porous Femoral and Harris-Galante Porous I and II Acetabular Components

This study examined long-term survivorship of primary total hip arthroplasty (THA) using cementless Harris-Galante porous femoral and Harris-Galante porous I or II acetabular components. Of 113 hips (101 patients) studied, 60 hips (53 patients) were available for follow-up at a mean of 17.2 years after surgery. A total of 10 hips had documented revision, and 2 hips had failed radiographically. The average Harris hip score was 82. Radiographically, 12 hips demonstrated eccentric wear, 8 had osteolysis, and 1 had a broken tine. The overall survival rate was 87.7%; the mean volumetric wear rate was 74.96 mm³; and the mean polyethylene linear penetration rate was 0.153 mm/y, similar to that of well-cemented THA in other series. This long-term outcome for an early-generation cementless THA is promising and provides a standard by which to judge the newer generation of cementless implants.     

Differences in Highly Cross-Linked Polyethylene Wear Between Zirconia and Cobalt-Chromium Femoral Heads in Japanese Patients : A prospective,randomized study

The purpose of this study was to compare highly cross-linked polyethylene wear between the zirconia head and the cobalt-chromium head in Japanese patients. A prospective, randomized study was performed to evaluate the outcomes in 32 hips that had zirconia heads and in 30 hips that had cobalt-chromium heads. The mean follow-up periods of both groups were same (5 years). There were no significant differences between the zirconia head and the cobalt-chromium head in the mean polyethylene linear wear per year and the mean volumetric polyethylene wear per year in the steady phase. This study indicates that zirconia head offers no benefits over metal head in terms of wear reduction at 5 years in Japanese patients who have lightweight and thin polyethylene liners.     

Wear Comparison Between Conventional and Highly Cross-Linked Polyethylene Against a Zirconia Head : A Concise Follow-Up,at an Average 10 Years,of a Previous Report

We previously reported the results of wear comparison at a minimum of 5 years between highly cross-linked polyethylene (HXLPE) and conventional polyethylene (PE) against a zirconia femoral head. We now report the mean wear at 10 years for 52 patients (56 hips) of the original cohort of 61 patients (65 hips) who had undergone primary total hip arthroplasty at our hospital between November 1999 and August 2000. The mean steady-state linear wear rate of HXLPE was 0.045 mm/y, compared with 0.080 mm/y for conventional PE (P = .0003). The incidence of osteolysis was 25% in the conventional PE group compared with 0% in the HXLPE group. Our study demonstrated that the steady-state wear rate for HXLPE remains significantly lower than that for conventional PE against a zirconia femoral head at a mean of 10 years after implantation.     

Comparing In Vivo Performance of Two Highly Cross-Linked Polyethylene Thermal Treatments: Remelting vs Annealing in Acetabular Liners

BackgroundThe introduction of highly cross-linked polyethylene (HXLPE) acetabular liners has greatly improved the wear performance of metal-on-PE bearing surfaces used in total hip arthroplasty. Changing the sterilization environment and adding thermal treatments, such as remelting or annealing, were introduced to limit on-shelf and in vivo oxidation of cross-linked liners. This study compares the wear properties of the remelted A-CLASS (MicroPort) HXLPE liner to a sequentially annealed HXLPE.MethodsThis retrospective study assessed linear and volumetric wear rates using Martell Hip Analysis Suite, and clinical performance through incidences of revision surgeries. A total of 80 remelted and 53 annealed liners were included in the wear analysis. All hips were reviewed for revisions.ResultsThere were no significant differences in steady-state linear or volumetric wear rates for remelted and annealed liners, 0.01 (?0.07 to 0.14) vs ?0.01 (?0.11 to 0.1) mm/y (P = .28) and ?1.03 (?30.99 to 45.43) vs ?1.31 (?32.23 to 23.70) mm³/y (P = .30), respectively. Both cohorts were below the 0.1 mm/y linear wear threshold. The wear rates for patients with femoral head sizes ≥36 mm were not significantly different than those with 32 and 28 mm femoral head sizes (P = .60). Similarly, wear rates for patients with an excessively vertical acetabular component (>50°) were not significantly different than those with standard acetabular component orientations (P = .97). No hips were revised due to liner-related complications.ConclusionThe wear rates of the A-CLASS remelted HXLPE acetabular liner wear rates were comparable to those of a sequentially annealed HXLPE. Further long-term studies are required to ensure acceptable resistance to fatigue and in vivo oxidation.     

Differences in Femoral Head Penetration Between Highly Cross-Linked Polyethylene Cemented Sockets and Uncemented Liners

BackgroundThis study aimed at investigating differences in femoral head penetration between highly cross-linked polyethylene (HXLPE) cemented sockets and uncemented liners during 5 years postoperatively.MethodsNinety-six patients (106 hips) with a mean age of 64.4 (range, 35-83) years underwent total hip arthroplasty using a HXLPE cemented socket or liner and were respectively divided into cemented (35 patients [37 hips]) and uncemented (61 patients [69 hips]) groups. Femoral head penetrations were evaluated on both anteroposterior (AP)-view and Lauenstein-view radiographs, and mean polyethylene (PE) wear rates were calculated based on femoral head penetration from 2 to 5 years. Multivariate analyses were performed to assess risk factors for PE wear.ResultsAt 5 years postoperatively, the cemented and uncemented groups exhibited proximal direction femoral head penetrations of 0.103 mm and 0.124 mm (P = .226) and anterior direction penetrations of 0.090 mm and 0.151 mm (P = .002), respectively. The corresponding mean PE wear rates were 0.004 mm/y and 0.009 mm/y in the AP-view (P = .286) and 0.005 mm/y and 0.012 mm/y in the Lauenstein-view (P = .168), respectively. Left-side operation and high activity were independent risk factors for PE wear on AP-view.ConclusionWhen HXLPE was used, all mean PE wear rates were very low and those of cemented sockets and uncemented liners were very similar. PE particle theory suggests that the occurrence of osteolysis and related aseptic loosening might consequently decrease.     

Comparison of Surgical Outcomes Between Standard and Elevated-Rim Highly Cross-Linked Polyethylene Acetabular Liners in Primary Total Hip Arthroplasty With Minimum 15-Year Follow-Up: Single-Center,Retrospective Cohort Study

BackgroundThe aims of the present study are to (1) conduct the longest-to-date follow-up wear analysis of the highly cross-linked polyethylene acetabular liners, (2) assess the incidence of femoral and acetabular osteolysis, and (3) compare the surgical outcomes between standard and elevated-rim acetabular liners in primary total hip arthroplasty (THA).MethodsIn this retrospective cohort study, we evaluated 112 primary THAs performed by a single experienced arthroplasty surgeon at our institution between March 2000 and December 2003. Patients were classified based on the type of acetabular liner used: standard or elevated-rim liner. For evaluation of surgical outcomes, the following data were collected: acetabular cup position (anteversion and inclination), wear rate (linear and volumetric), presence of osteolysis, history of reoperation (all-cause and wear-related), complications (deep joint infection, dislocation, and periprosthetic fracture), and Harris hip score at last follow-up.ResultsLinear and volumetric wear rates were 0.028 mm/y (0.000-0.145 mm/y) and 11.641 mm³/y (0.000-70.000 mm³/y) in the standard group and 0.026 mm/y (0.000-0.094mm/y) and 9.706 mm³/y (0.000-33.000 mm³/y) in the elevated-rim group, respectively. These rates were not significantly different between groups. One case of osteolysis was confirmed in the standard group, whereas no osteolysis was observed in the elevated-rim group.ConclusionWe suggest that elevated-rim highly cross-linked polyethylene acetabular liners might be a good implant option that can be used safely.     

Eight-year wear analysis in Longevity highly cross-linked polyethylene liners comparing 26- and 32-mm heads

Introduction  

Although wear reduction of highly cross-linked polyethylene has been demonstrated to be independent of femoral head diameter in some simulation studies, the clinical effects of femoral head diameter on wear of highly cross-linked polyethylene sockets remain unclear. We compared the in vivo wear of Longevity highly cross-linked polyethylene liners at 8-year follow-up using 26- or 32-mm cobalt-chromium heads.     

In Vivo Femoral Head Damage and Its Effect on Polyethylene Wear

The purposes of this study were to determine the spectrum of femoral head damage in patients undergoing revision total hip arthroplasty and to determine the impact of that damage on polyethylene wear. One hundred eight consecutive modular metal femoral heads were retrieved at revision surgery. The mean roughness (Ra) value was 0.18 ± 0.18 μm. The roughest femoral heads (mean Ra, 0.56 μm) were from retrievals correlated with mode 2 wear (recurrent dislocation and complete wear through of the polyethylene liner). Five million cycles of wear tests were performed using retrieved femoral heads against both new conventional and highly cross-linked polyethylene. The mean wear rate of conventional polyethylene was 15.9 ± 4.3 mg and that of highly cross-linked polyethylene was 0.04 ± 0.14 mg per 1 million cycles (P < .001). Highly cross-linked polyethylene was more resistant to wear than conventional polyethylene, even when mated against roughened femoral heads.     

Alarming wear of the first-generation polyethylene liner of the cementless porous-coated Biomet Universal cup: 107 hips followed for mean 6 years

Wear of the socket liner and resulting osteolysis are the major causes of failure in cementless hip arthroplasties. We report alarming wear of the first-generation polyethylene liner of the cementless porous-coated Biomet Universal cup. Radiographs of 107 primary hip arthroplasties were analyzed retrospectively. The mean follow-up time was 74 (47-91) months. The linear wear of the polyethylene liners was assessed using a modification of the Livermore method. The median linear wear was 1.0 (0-6.2) and the median linear wear rate was 0.17 mm/year. There was a statistically significant difference between the 28 mm and 32 mm femoral head groups both in the volumetric wear and in the volumetric wear rate. The median linear wear was 0.28 mm/year and 0.14 mm/year for the 32 mm and 28 mm heads, respectively. So far, 14 revisions have been performed or have been scheduled because of excessive wear of the polyethylene liner. In regression analysis, the factors related to the wear rate were the 32 mm size of the femoral head and screw fixation of acetabular shell. We found that the cases with calcar rounding were associated with significantly greater wear. Possible reasons for increased wear of the Hexloc liner may be the cylindrical design, thin polyethylene, and poor quality of the polyethylene. Regular clinical and radiographic follow-ups are recommended especially for hips with 32 mm femoral heads or with screw fixation. If progressive wear of the liner is observed, revision must be considered.     

Wear and Range of Motion of Different Femoral Head Sizes

Femoral head sizes greater than 32 mm are more prevalent with current total hip arthroplasty. We hypothesized that linear wear rates of Durasul highly cross-linked polyethylene would not differ with different head sizes. We also compared the range of motion of the hip. Ninety-four consecutive arthroplasties in 84 patients were studied for a mean 3.6 ± 0.7 years. There was no statistical difference in linear wear rates and annual or total penetration rates when 28-mm and 32-mm heads were compared to 38-mm and 44-mm heads. Volumetric wear was 12.4 mm³/y higher with bigger heads. Range of motion did not differ. Larger femoral head sizes show no evidence of an accelerated wear pattern when used with Durasul.