Total hip arthroplasty using highly cross-linked polyethylene in patients younger than 50 years with minimum 10-year follow-up

In Young Patients Undergoing Total Hip Arthroplasty, Is There a Correlation Between Activity Level and Wear of Highly Cross-Linked Polyethylene?

Background

Total hip arthroplasty (THA) effectively restores mobility, reduces pain, and enhances the quality of life of patients of all ages. Despite its benefits, concerns regarding the long-term effects of high-impact activities and sports on implant longevity require further study. This study investigated the effect of activity level on long-term radiographic wear of highly cross-linked polyethylene (HXLPE) in young patients undergoing THA.

Methods

Between 1999 and 2008, 785 patients (909 hips) aged ≤50 underwent primary THA using first-generation HXLPE liners from 4 different vendors with either metal or ceramic heads. Functional activity and participation questionnaires, including the Hip Injury and Osteoarthritis Outcome Score (HOOS Jr), University of California Los Angeles (UCLA) activity scale, and High-Activity Arthroplasty Score (HAAS), were surveyed in 2018 to 2019. The response rate was 44%. Radiographic linear wear rates were measured using the ROMAN software in patients who had completed questionnaires and had radiographs taken at least 10 years apart, leaving a final cohort of 249 patients (284 hips). Multivariate analyses were performed to determine the relationship between HXLPE wear rates and activity scores.

Results

At the time of the survey, approximately 10% of the patients performed high-impact activities not-recommended by consensus guidelines. The HXLPE linear wear rate was 0.036 mm/year (SD: 0.026). Patients with higher activity levels, as measured on the continuous UCLA/HAAS activity scale, did not exhibit increased wear (β = -0.0009; p = 0.31). Stair climbing was correlated with increased wear rates (β = 0.0066; p = 0.004), whereas walking (β = 0.0005; p = 0.66) and running (β = 0.0017; p = 0.30) were not significantly correlated. Patients performing nonrecommended activities did not show increased wear rates compared with those performing recommended activities (β = 0.0063; p = 0.19).

Conclusions

Linear wear rates of first-generation HXLPE were not related to functional activity or participation in high-impact activities. Future research should include longitudinal assessments of activity levels and data on other potential complications related to high-impact sports to provide robust evidence regarding recommended activity level postoperatively.

Level of Evidence

Level III, Retrospective Comparative Study. See Instructions for Authors for a complete description of levels of evidence.

No Revisions Attributable to Wear of Highly Cross-Linked Polyethylene Liners: A Long-Term Follow-Up Study

BACKGROUND

There is a paucity of data beyond 15 years on the survivorship of total hip arthroplasty since the introduction of highly cross-linked polyethylene (HXLPE) liners. Our aim was to evaluate implant survivorship, liner wear rates, and clinical outcomes after primary total hip arthroplasty using HXLPE liners implanted between 1999 and 2002.

METHODS

Between 1999 and 2002, 690 primary total hip arthroplasties utilizing 28-mm femoral heads and HXLPE liners of a single design were identified using our institutional total joint registry. Femoral heads were made of metal in 96% of cases and ceramic in 4%. The mean age was 56 years, 48% were women, and the mean body mass index was 30. Survivorship analyses were performed for the outcomes of implant revision, reoperation, and complications for the entire cohort. Linear HXLPE liner wear rates were determined on 197 hips with radiographs with more than 18.5 years of follow-up.

RESULTS

At 20 years, survivorship free of revision was 94%, free of reoperation was 92%, and free of any complication was 81%. There were no documented wear-related revisions. The linear wear rate at a mean of 20.3 years postoperatively was 0.02 mm/y. There was no statistically significant difference in measured wear observed between the first available postoperative radiographs and those taken at the final follow-up. The use of elevated liners, patient body mass index, age, preoperative diagnosis, acetabular component inclination, and anteversion angles were not associated with increased wear rates. Mean Harris hip scores improved from 52 preoperatively to 90 at greater than 18.5 years CONCLUSIONS: Primary total hip arthroplasties using a single first-generation HXLPE liner demonstrated excellent survivorship and clinical outcomes at long-term follow-up with no wear-related revisions. Wear rates of HXLPE liners at 20 years are exceedingly low and are not significantly impacted by acetabular component position or patient-dependent variables such as BMI.

LEVEL OF EVIDENCE

IV.

Outcomes of Osteochondral Allograft Transplantation for Femoral Head Cartilage Lesions: Minimum 2-Year Follow-Up

BACKGROUND

The surgical management of large osteochondral lesions of the femoral head in young, active patients remains controversial. Fresh osteochondral allograft (OCA) transplantation can be a highly effective treatment for these lesions in some patients. This study investigated survivorship as well as clinical and radiographic outcomes after fresh OCA transplantation at a minimum 2-year follow-up (mean, 6.6 years; range, 0.6 to 13.7 years).

METHODS

A retrospective review of 29 patients who underwent plug OCA transplantation for focal femoral head osteochondral lesions between 2008 and 2021 was performed. Patients were assessed clinically using the modified Harris Hip score (mHHS) preoperatively and at each follow-up visit. Postoperative radiographs were evaluated for graft integrity and osteoarthritis severity. Kaplan-Meier survivorship analyses with 95% confidence intervals (CIs) were performed for the endpoint of conversion to total hip arthroplasty (THA).

RESULTS

Overall graft survivorship for included patients was 78.4% (95% CI: 62.9 to 93.9) and 62.7% (95% CI: 39.6 to 85.8) at 5 and 10 years, respectively. There were ten patients (34.5%) who underwent conversion to THA. There was a significant difference using the log-rank test between survival for patients who had a preoperative diagnosis of osteonecrosis (ON) versus those who had other diagnoses (P = .002). The ten-year survival for those who had ON was 41.8% (95% CI: 4.8 to 78.8), and the ten-year survival for diagnoses other than ON was 85.7% (95% CI: 59.8 to 100). The mean mHHS score improved significantly (P < .001) from 48.9 (19 to 84) preoperatively to 77.4 (35 to 100) at the final follow-up. There were twenty patients (69.0%) who had mHHS ≥ 70 at the latest follow-up. Arthritic progression, indicated by an increase in the Kellgren and Lawrence grade, occurred in 7 hips (26.9%).

CONCLUSIONS

An OCA transplantation is a viable treatment option for osteochondral defects of the femoral head in young, active patients who have minimal preexisting joint deformity. It may delay the progression of arthritis and the need for THA. Patients who had a preoperative diagnosis of ON had worse clinical outcomes than those who had other diagnoses.

Ten Year Outcomes of Contemporary Total Hip Arthroplasty in Adolescent and Young Adult Patients are Favorable

BACKGROUND

The purpose of this study was to assess 10-year patient-reported outcome measures, complications, polyethylene wear-rates, and implant survivorships in patients ≤30 years of age treated with contemporary total hip arthroplasty (THA).

METHODS

We retrospectively assessed 121 patients (144 hips) who underwent THA at age ≤30 years (mean 23 [range, 11 to 30]) at an average follow-up duration of 10.7 years (range, 8 to 17). Highly-crosslinked polyethylene acetabular liners were used in all cases. Femoral heads were ceramic (74%) or cobalt-chrome (26%). There were 52 hips (36%) that had previous surgery and 31 hips (22%) were in patients who had associated major systemic comorbidities. We analyzed the modified Harris Hip scores, University of California Los Angeles Activity Scores, major complications, polyethylene wear-rates, and implant survivorships.

RESULTS

At final follow-up, the average modified Harris Hip scores improved from 47 (±15.1) to 81 (±19.5) with an average 34-point improvement. The University of California Los Angeles scores improved from 4.0 (±2.3) to 6.0 (±2.4). The major complication rate was 5.6%. There were 6 hips (4.2%) that were revised. Indications for revision included instability (3, 2.1%), late infection (1, 0.7%), liner dissociation (1, 0.7%), and acetabular loosening (1, 0.7%). Mean linear (0.0438 mm/y) and volumetric (29.07 mm3/y) wear rates were low. No periprosthetic osteolysis was detected in any hip. Survivorship free from revision for any reason was 97.2, 95.8, and 95.8% at 5, 10, and 15 years.

CONCLUSIONS

Contemporary THA in patients ≤30 years of age is associated with marked clinical improvements at 10-year follow-up and encouraging survivorship estimates at 15 years.

Total Hip Arthroplasty: An Update on Navigation, Robotics, and Contemporary Advancements

While total hip arthroplasty (THA) remains effective for improvement of pain and function in patients with osteoarthritis and avascular necrosis, there remain areas of continued pursuit of excellence, including decreasing rates of dislocation, leg length discrepancy, implant loosening, and infection. This review article covers several bearing surfaces and articulations, computer-assisted navigation and robotic technology, and minimally invasive surgical approaches that have sought to improve such outcomes. Perhaps the most significant improvement to THA implant longevity has been the broad adoption of highly cross-linked polyethylene, with low wear rates. Similarly, navigation and robotic technology has proven to more reproducibly achieve intraoperative component positioning, which has demonstrated clinical benefit with decreased risk of dislocation in a number of studies. Given the projected increase in THA over the coming decades, continued investigation of effective incorporation of technology, soft tissue-sparing approaches, and durable implants is imperative to continued pursuit of improved outcomes in THA.

Wear, Osteolysis, and Aseptic Loosening Following Total Hip Arthroplasty in Young Patients with Highly Cross-Linked Polyethylene: A Review of Studies with a Follow-Up of over 15 Years

Total hip arthroplasty (THA) has in recent years trended toward a younger, more physically demanding patient population. Mid- to long-term studies of all ages of THA patients using highly cross-linked polyethylene (HXLPE) have been favorable, but concerns about its long-term failure and wear-related complications remain for young THA patients. In this narrative review, a search of the PubMed/MEDLINE and Cochrane databases was performed, and we identified six studies with a minimum 15-year follow-up of HXLPE with various femoral head materials. Wear-related revisions were exceedingly low for patients under the age of 55, with variable reports of non-clinically significant osteolysis. Higher activity levels, a larger femoral head size, and femoral head material were not associated with greater long-term wear rates. Young THA with metal or ceramic on HXLPE is exceedingly durable with favorable outcomes at follow-ups of over 15 years.

Factors Related to Expectations in Individuals Waiting for Total Knee Arthroplasty

Purpose

There is no consensus on how age and expectations influence planning for total knee arthroplasty (TKA). This study developed and evaluated a new expectation questionnaire and assessed the relationship between preoperative expectations and patient characteristics.

Method

The questionnaire evaluated expectations for mobility, pain, participation, and rate of recovery after surgery. Fifty-five participants completed a 6-minute walk test and expectation questionnaire prior to TKA; 17 participants repeated the questionnaire one week later for reliability testing. Analysis of the questionnaire included intra-class correlation coefficient (ICC), homoscedasticity, skewness, kurtosis, multicollinearity, and descriptive measures. A four-step hierarchical linear regression was completed to determine the relationship of patient age, BMI, previous contralateral TKA, and 6-minute walk test scores to expectations.

Results

The questionnaire showed good/high test-retest reliability (ICC 0.84; 95% CI: 0.57, 0.94; p > 0.001). The final model was significant in predicting expectation scores R2 = 0.19 (p = 0.017).

Conclusions

This questionnaire reliably measures patient expectations before TKA; however, further research is needed. Although we anticipated younger age to be related to higher expectations, higher function prior to TKA appears to be more strongly associated with higher expectations.

Midterm Results of Contemporary Uncemented Total Hip Arthroplasty in Patients 45 Years or Younger

Total hip arthroplasty (THA) in young patients has varying results, and some reports show inferior results when compared with those of older patients. This study evaluated the outcomes of contemporary uncemented THA in patients 45 years or younger. This was a retrospective review from 2003 to 2015 at an academic institution. Three hundred one uncemented THAs in 232 patients 45 years or younger were evaluated. All patients had a minimum follow-up of 5 years. Ninety-day complications, survivorship free of revision, and dislocations were evaluated. Mean age was 35.7 years, 43.1% of patients were women, and mean follow-up was 9.3 years. Ninety-day complications included 26 emergency department visits, 11 readmissions, 3 revisions, and 3 dislocations. The rate of 10-year survivorship free of revision was 85.5%, and the rate of 10-year survivorship free of aseptic revision was 87.7%. Excluding metal-on-metal (MOM) THAs, 10-year aseptic survivorship was 93.3%. The most common reasons for revision were adverse local tissue reaction after MOM THA (16 hips) and periprosthetic joint infection (6 hips). In a multivariable logistic regression model, sickle cell disease (SCD) and conversion THA were associated with 90-day readmissions. Both MOM THA and SCD were associated with revision (P<.05). Patients who are 45 years or younger undergoing THA (excluding MOM articulation) had a rate of 10-year survival free of aseptic revision of 93.3%. At 9.3 years' mean follow-up, THA in young patients was associated with low revision rates with acceptable risk of prosthetic joint infection and dislocation. Patients with SCD are at increased risk for early readmission and revision at latest follow-up. [Orthopedics. 2023;46(1):e45-e51.].

Thin highly cross-linked polyethylene liners combined with large femoral heads in primary total hip arthroplasty show excellent survival and low wear rates at a mean follow-up of 12.8 years

AIMS

Several short- and mid-term studies have shown minimal liner wear of highly cross-linked polyethylene (HXLPE) in total hip arthroplasty (THA), but the safety of using thinner HXLPE liners to maximize femoral head size remains uncertain. The objective of this study was to analyze clinical survival and radiological wear rates of patients with HXLPE liners, a 36 mm femoral head, and a small acetabular component with a minimum of ten years' follow-up.

METHODS

We retrospectively identified 55 patients who underwent primary THA performed at a single centre, using HXLPE liners with 36 mm cobalt-chrome heads in acetabular components with an outer diameter of 52 mm or smaller. Patient demographic details, implant details, death, and all-cause revisions were recorded. Cox regression and Kaplan-Meier survival was used to determine all-cause and liner-specific revision. Of these 55 patients, 22 had a minimum radiological follow-up of seven years and were assessed radiologically for linear and volumetric wear.

RESULTS

Overall survival rate for all-cause revision was 94.5% (95% confidence interval (CI) 81.7% to 97.2%) at a mean follow-up of 12.8 years (10.9 to 18.7). Three patients were revised, none for liner wear, fracture, or dissociation. A total of 22 patients were included in the radiological analysis (mean follow-up 9.9 years (7.5 to 13.7)). Mean linear liner wear was 0.085 mm (95% CI -0.086 to 0.257) and the volumetric wear rate was 11.097 mm³/year (95% CI -6.5 to 28.7).

CONCLUSION

Using HXLPE liners with 36 mm heads in 52 mm acetabular components or smaller is safe, with excellent survival and low rates of linear and volumetric wear at medium-term follow-up. Patients did not require revision surgery for liner complications such as fracture, dissociation, or wear. Our results suggest that the advantages of using larger heads outweigh the potential risks of using thin HXLPE liners.Cite this article: Bone Joint J 2023;105-B(1):29-34.

Long-Term Wear-Related Complications of Cross-Linked Versus Conventional Polyethylene After Total Hip Arthroplasty: A Meta-Analysis

BACKGROUND

Highly cross-linked polyethylene (HXLPE) liners have been developed to address the wear-related problems associated with conventional polyethylene (CPE) such as osteolysis or aseptic loosening in total hip arthroplasty (THA). In this systematic meta-analysis, we compared the long-term efficacy in preventing radiological osteolysis and revision surgery between HXLPE and CPE.

METHODS

We included 14 studies that compared HXLPE and CPE reporting the incidence of wear-related complications with a minimum follow-up of 10 years. We investigated 5 wear-related complications: osteolysis, excessive wear, linear wear rate, revision surgery due to wear, and progress of osteolysis/aseptic loosening. We conducted a pair-wise meta-analysis to estimate odds ratio (OR) and a proportional meta-analysis to estimate the incidence of each complication.

RESULTS

Among 1,175 THAs, 220 osteolysis and 78 wear-related revisions were detected. The use of HXLPE reduced the risk of overall osteolysis (OR 0.30; P = .001), excessive wear (OR 0.10; P < .001), linear wear rate (weighted mean difference 0.09; P < .001), the risk of overall wear-related revisions (OR 0.06; P < .001), and revisions due to aseptic loosening (OR 0.23; P = .015). As per the proportional meta-analysis, the pooled prevalence of osteolysis, excessive wear, and the overall wear-related revision rate were 14%, 8%, and 3% in HXLPE and 25%, 33%, and 20% in CPE, respectively.

CONCLUSION

The current evidence shows that HXLPE dramatically reduced the rate of osteolysis and wear-related revision surgery. However, as polyethylene wear and osteolysis still lead to revision surgery, ongoing clinical and retrieval studies are required to analyze long-term outcomes.

Large Femoral Heads in Total Hip Arthroplasty With Vitamin E Highly Cross-Linked Polyethylene: Head Penetration Rates Compared to Highly Cross-Linked Polyethylene

BACKGROUND

Highly cross-linked polyethylene with vitamin E (VE-HXLPE) has shown superior tribological properties and has been rapidly adopted in total hip arthroplasty. However, the majority of studies compare VE-HXLPE to conventional or moderately cross-linked polyethylene using standard femoral head sizes. This study's purpose was 2-fold: (1) compare radiographic femoral head penetration (FHP) between VE-HXLPE and HXLPE and (2) evaluate FHP in large femoral heads ≥40 mm.

METHODS

One hundred forty-two consecutive primary total hip arthroplasties using ceramic femoral heads (n = 84 VE-HXLPE; n = 58 HXLPE) in a single implant system were retrospectively reviewed. FHP was measured radiographically utilizing Martell method at 4-week, 1-year, and latest radiographs. FHP, cup position, and demographic variables were compared between VE-HXLPE and HXLPE liners.

RESULTS

Median linear FHP was lower for VE-HXLPE compared to HXLPE during the initial "bedding-in" period between 4-week and 1-year (0.383 vs 0.551 mm, P = .650) and between 1-year and latest follow-up (0.131 vs 0.270 mm/y, P = .636) although without statistical significance. Acetabular cup inclination and anteversion did not influence linear or volumetric FHP (P ≥ .204). Large femoral heads (≥40 mm) were predictive of higher FHP during the early bedding-in period (P ≤ .025) but did not have an effect beyond 1 year in multivariate regression with numbers available. No radiographic osteolysis was observed in any case.

CONCLUSION

These findings support others that VE-HXLPE is the optimal polyethylene bearing surface to minimize FHP during the bedding-in period and beyond. Surprisingly, large ceramic femoral heads appear to influence FHP during the initial bedding-in period but do not increase FHP beyond 1 year. Further longer term follow-up remains warranted.

LEVEL OF EVIDENCE

III.

Low Wear at 10-Year Follow-Up of a Second-Generation Highly Cross-Linked Polyethylene in Total Hip Arthroplasty

BACKGROUND

Characterizations and factors influencing longer term performance of second-generation sequentially irradiated and annealed highly cross-linked polyethylene (HXLPE) are lacking. We evaluated patients who underwent total hip arthroplasty with HXLPE at mean 10-year follow-up for (1) linear and volumetric wear rates, (2) patient and implant characteristics, (3) implant survivorships, and (4) functional scores.

METHODS

We evaluated 130 hips (110 patients) that received HXLPE acetabular liners at a single center. The mean age was 56 years (range, 20-79 years), with a mean follow-up of 10 years (range, 8-15). Radiographic linear (millimeters/year) and volumetric (cubic millimeters/year) wear rates were quantified using radiographic analysis. Survivorship was assessed by all-cause and wear-related revision rates. Functional outcomes were assessed by Short Form 12 and modified Harris Hip Scores.

RESULTS

The mean linear wear rate was 0.02 ± 0.03 mm/y, and the mean volumetric wear rate was 12.6 ± 5.3 mm³/y. Younger age had higher volumetric wear (total and yearly, P = .01). Increasing body mass index trended toward higher total and yearly linear (both, P ≤ .09) and volumetric wear (both, P ≤ .07). Ten patients required revisions, with an all-cause survivorship of 92% and a wear survivorship of 100%. The mean modified Harris Hip Scores was 84, and the mean Short Form 12 scores were 46 (physical) and 55 (mental).

CONCLUSION

We observed low linear and volumetric wear rates for HXLPE at 10-year mean follow-up. Younger age and higher body mass index at the time of surgery may be important patient characteristics influencing long-term wear. These results illustrate the potential for this second-generation HXLPE to be an appropriate long-term total hip arthroplasty interface.

Third-Generation Ceramic-on-Ceramic Total Hip Arthroplasty in Patients with Osteonecrosis of the Femoral Head: A 10- to 16-year Follow-up Study

BACKGROUND

Long-term follow-up results of ceramic-on-ceramic (COC) total hip arthroplasty (THA), specifically, in patients with osteonecrosis of the femoral head (ONFH) are unknown. We evaluated (1) clinical results and radiological outcomes, (2) ceramic-related complications: noise and ceramic fracture, (3) osteolysis, and (4) survivorship after alumina COC THA in ONFH patients with longer than 10-year follow-up.

METHODS

From May 2003 to June 2009, 325 ONFH patients (403 hips) underwent primary THAs at our department. Among them, 231 patients (293 THAs) were followed for 10 to 16 (mean, 12.9) years. There were 148 men and 83 women, their mean age at the time of THA was 47.2 years, and their mean body index was 24.0 kg/m2. The postoperative CT scans were done in 160 hips.

RESULTS

Grinding sensation or squeak was noted in 6.8% (20/293), ceramic head fracture occurred in 2.4% (7/293) and acetabular osteolysis developed in 0.7% (2/293). All 7 ceramic fractures occurred in 28-mm short-neck heads. There was no detectable wear or prosthetic loosening, and the 16-year survivorship was 96.0% (95% confidence interval; 93.8% to 98.2%). The mean Harris hip score was 91.7 (range, 84 to 100) points at the final follow-up.

CONCLUSIONS

The 10- to 16-year results of alumina COC THAs were encouraging with an excellent survivorship. However, ceramic fracture and noise still remain matters of concern. We recommend not to use 28-mm short-neck ceramic head to avoid ceramic head fractures.

LEVEL OF EVIDENCE

III.

Fixation vs Arthroplasty for Femoral Neck Fracture in Patients Aged 40-59 Years: A Propensity-Score-Matched Analysis

Background

Methods

Results

Conclusions

The superior accuracy of a novel method in total hip wear calculations following radiographic measurement

Background

Polyethylene wear is one of the major concerns of orthopedic surgeons. However, there is no standardized calculation method for the wear rate following radiographic measurement. The purpose of this study was to propose a novel method of wear calculation and to compare its accuracy with a representative conventional method.

Methods

Relative position of the center of the femoral head to that of the cup progresses in one direction following arthroplasty surgery because of bedding-in and wear. We predetermined the amount of bedding-in, wear rate, and random error in measuring the head center position in a 2-dimensional plane. We calculated the wear rate using the head center coordinates over a certain number of measurement periods using a representative conventional method and our novel method. The conventional method consisted of transforming vector data into scalars and conducting a least-squares method. The least-squares method was directly applied to each component of the vector in the novel method. We evaluated the accuracy of these methods by comparing the expected value for the wear rate with their predetermined true values.

Results

If the error were limited to being random, the novel method could provide the predetermined wear rate as the calculation result. However, the conventional method could not.

Conclusion

We recommend using the novel method for the wear calculation rather than the conventional method because of its mathematical accuracy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04964-5.

A review of advances in tribology in 2020–2021

Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021, and reviewed as the representative advances in tribology research worldwide. The survey highlights the development in lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology, providing a show window of the achievements of recent fundamental and application researches in the field of tribology.

Use of Total Hip Arthroplasty in Patients Under 21 Years Old: A US Population Analysis

BACKGROUND

The purpose of this study is to evaluate trends in the use of total hip arthroplasty (THA) in the United States in patients under 21 years of age. Specifically, we examined the frequency of THA in this patient population over the past 2 decades, the epidemiologic characteristics of patients under 21 who underwent THA, and the characteristics of the hospitals where these procedures were performed.

METHODS

We retrospectively reviewed the Kids' Inpatient Database, an inpatient US national weighted sample of hospital admissions in patients under 21 from approximately 4200 hospitals in 46 states. We queried the database using Current Procedural Terminology codes for elective and non-elective primary THA for the years 2000-2016. We utilized the International Classification of Diseases, Ninth Revision and International Classification of Diseases, Tenth Revision codes to determine primary diagnoses.

RESULTS

The weighted total number of THAs performed in patients under 21 in the Kids' Inpatient Database increased from 347 in 2000 to 551 in 2016. The most common diagnoses were osteonecrosis, osteoarthritis, and inflammatory arthritis. The frequency of THA for osteonecrosis increased from 24% in 2000 to 38% in 2016, while the frequency of THA for inflammatory arthritis decreased from 27% in 2000 to 4% in 2016.

CONCLUSION

The number of THAs in patients under 21 in the United States has increased over the past 2 decades and these procedures are increasingly performed in urban teaching hospitals. The decrease in THA for inflammatory arthritis in this population likely reflects improvements in medical management during the study period.

No Difference in Dislocation Rates Comparing Large Diameter Jumbo Femoral Heads and Dual-Mobility Bearings in Revision Total Hip Arthroplasty

BACKGROUND

Dual-mobility (DM) bearings reduce instability in revision total hip arthroplasty (THA); however, DM bearings are costly and reports of corrosion have recently emerged. Furthermore, no study has compared DM to standard bearings with large diameter femoral heads ≥40-mm. This study's purpose was to compare postoperative dislocation rates of standard and DM bearings with large femoral heads after revision THA.

METHODS

A retrospective review of 301 consecutive revision THAs was performed. The mean follow-up was 37.1 months. To isolate the effect of the double articulation, standard and DM bearings with femoral heads ≥40-mm were compared. Outcomes were postoperative dislocation and reoperation within 90 days.

RESULTS

The cohort consisted of 182 standard bearings and 75 DM bearings. There were no differences in revision indication comparing standard and DM bearings (P = .258). Overall dislocation rate was 8.6% (22 of 257). The dislocation rate was 5.7% for standard bearings with ≥40-mm femoral heads compared with 6.9% in DM bearings with ≥40-mm femoral heads (P = 1.000). In multivariate analysis, lower body mass index (odds ratio 1.72), female sex (odds ratio 2.01), and decreased outer femoral head diameter-to-cup component size ratio (odds ratio 1.64) were predictors of postoperative dislocation regardless of bearing type.

CONCLUSION

This study showed no difference in dislocation rates between standard and DM bearings when comparing similar femoral head diameters of ≥40-mm used in revision THAs. Considering the cost and potential deleterious issues associated with additional interfaces, DM bearings should be used judiciously considering similar results may be achieved with single-articulation bearings using large femoral heads.

LEVEL OF EVIDENCE

Level III.

Wear analysis of the first-generation cross-linked polyethylene at minimum 10 years follow-up after THA: no significant effect of sports participation

The impact of sports on long-term wear of highly cross-linked polyethylene (XLPE) after total hip arthroplasty (THA) is not fully understood. We investigated (1) the wear performance of the first-generation XLPE, and (2) whether sports participation influences the steady wear rate of XLPE. The femoral head penetration into the cup was measured digitally on radiographs of hips undergoing THA with XLPE. We retrospectively reviewed data that included age, gender, body mass index, follow-up period, preoperative diagnosis, types of XLPE, ball diameter, head material, inclination of the cup, physical function score, and sports participation. Statistical analyses were applied to determine whether sports affect the wear of XLPE and which factors were associated with the steady wear rate. Creep and steady wear rate were found to be 0.18 mm and 0.005 mm/year, respectively. Sports participation, regardless of impact, provided no significant difference in the steady wear rate. Multiple regression analysis demonstrated that sports did not increase the steady wear rate. Our findings showed excellent wear performance of the first-generation XLPE at a minimum of ten years after THA, without significant effect of sports participation on the liner wear.

Highly cross-linked polyethylene still outperforms conventional polyethylene in THA: 10-year RSA results

Background and purpose - Cup wear in total hip arthroplasty (THA) can be affected by different manufacturing processes of the polyethylene (PE). We report the long-term wear pattern differences, as well as early creep behavior, between conventional PE and highly cross-linked PE (HXLPE) liners, as measured with radiostereometry (RSA) up to 10 years. We also compare migration and clinical outcome of 2 similar uncemented cups with different backside surface roughness.Patients and methods - We included 45 patients with primary osteoarthritis. 23 received a conventional liner and 22 an HXLPE liner in a similar uncemented cup, but with a slightly rougher surface. The patients were followed up with RSA and hip-specific outcome questionnaire (HOOS) at 3 months, 1, 2, 5, and 10 years.Results - During the first 3 months both liners showed expected deformation with mean proximal head penetration of 0.39 mm (conventional PE) and 0.21 mm (HXLPE). Between 3 months and 10 years there was a difference in annual wear with 0.12 mm/year for the conventional liner and 0.02 mm/year for the HXLPE liner. The cup with rougher surface had less initial migration but both types had stabilized after 3 months. The HOOS scores improved after surgery and remained high for both groups throughout the study period.Interpretation - Up to 10 years the HXLPE has consistent lower annual wear, possibly contributing to longer survival of the THA, compared with conventional PE. All patients reported good results regardless of liner type.

Total hip arthroplasty using highly cross-linked polyethylene in patients aged 50 years and younger : minimum 15-year follow-up

AIMS

Highly cross-linked polyethylene (HXLPE) has greatly improved the durability of total hip arthroplasty (THA) in young patients because of its improved wear characteristics. Few studies have followed this population into the second decade, and therefore the purpose of this investigation was to evaluate the clinical outcome for THA patients 50 years of age and younger at a minimum of 15 years postoperatively. The second purpose was to evaluate the radiological findings secondary to wear or mechanical failure of the implant.

METHODS

Between October 1999 and December 2005, 105 THAs were performed in 95 patients (53 female, 42 male) aged 50 years and younger (mean 42 years (20 to 50)). There were 87 patients (96 hips) that were followed for a minimum of 15 years (mean 17.3 years (15 to 21)) for analysis. Posterior approach was used with cementless fixation with a median head size of 28 mm. HXLPE was the acetabular bearing for all hips. Radiographs were evaluated for polyethylene wear, radiolucent lines, and osteolysis.

RESULTS

Clinical outcomes showed significant improvement of mean Harris Hip Scores from 52.8 (SD 13.5) preoperatively to 94.8 (SD 7.6) postoperatively. One hip was revised for recurrent instability, and there were no infections. No hips were revised for mechanical loosening or osteolysis. Mean polyethylene linear wear was 0.04 mm/year and volumetric wear was 6.22 mm³/year, with no significant differences between head size or material. Osteolysis was not present in any of the hips.

CONCLUSION

The use of HXLPE in THA for patients aged 50 years and younger has performed exceptionally well without evidence of significant wear causing mechanical loosening or necessitating revision. The radiolucent lines of the acetabular component must be followed to determine the prognostic significance. This investigation represents the longest clinical follow-up of a large, consecutive cohort of patients aged 50 years or younger with THA using HXLPE. This long-term analysis found negligible polyethylene wear, no incidence of aseptic loosening, and excellent clinical outcomes at and beyond 15 years of follow-up. Cite this article: Bone Joint J 2021;103-B(7 Supple B):78-83.

National Trends in Total Hip Arthroplasty Bearing Surface Usage in Extremely Young Patients Between 2006 and 2016

Background

Long-term implant durability is a key concern when considering total hip arthroplasty (THA) in young patients. The ideal bearing surface used in these patients remains unknown. The purpose of this study was to analyze trends in THA bearing surface use from 2006 to 2016 using a large, pediatric national database.

Methods

This was a retrospective review from January 1, 2006, to December 31, 2016, using the Kids’ Inpatient Database. International Classification of Diseases, 9^th revision and 10^th revision codes were used to identify patients who underwent THA and create cohorts based on bearing surfaces: metal-on-metal, metal-on-polyethylene, ceramic-on-polyethylene (CoP), and ceramic-on-ceramic (CoC). Annual utilization of each bearing surface and associated patient and hospital demographics were analyzed.

Results

A total of 1004 THAs were identified during the 11-year study period. The annual number of THAs performed increased by 169% from 2006 to 2016. The mean patient age was 17.1 years. The most prevalent bearing surface used in 2006 was CoC (37.3%), metal-on-metal (31.8%) in 2009, and CoP in 2012 and 2016 (50.6% and 64.8%, respectively). From 2006 to 2016, utilization of CoP increased from 5.0% to 64.8%, representing a 1196% increase over the study period.

Conclusions

The number of THAs performed in pediatric patients is increasing significantly. Although CoC was previously the most commonly used bearing surface in this patient population, CoP is currently the most common. Further investigation is needed to determine whether bearing longevity and clinical outcomes with CoP are superior to other bearing surfaces.

Recommendations for return to sports after total hip arthroplasty are becoming less restrictive as implants improve

INTRODUCTION

Total hip arthroplasty (THA) surgeries are expected to exponentially increase in the upcoming years, likely because of the overall broader indication of THAs. With these developments, an increasing number of younger (< 50 years) and active patients will receive surgical interventions, and expectations for an active lifestyle will accordingly increase. In addition, surgeons now have a growing array of techniques and implant materials to choose from. Despite these developments, evidence to provide the best standard-of-care to patients with high expectations for return to sports (RTS) is scarce and urgently needed. What recommendations do arthroplasty surgeons currently make to patients with high return to sports expectations, what factors may influence their recommendations and what surgical techniques and implant specifications are considered favorable in the treatment of patients with a more active lifestyle? This study was conducted to analyze the current recommendations, patient assessment, and patient counseling after THA to identify trends and relevant factors for surgical decision-making in patients with high-RTS expectations.

MATERIAL AND METHODS

We designed a questionnaire comprising five general items and 19 specific items that included 46 sub-items for hip arthroplasty and conducted a survey among 300 German surgeons specialized in arthroplasty at the German Arthroplasty Society (AE) to assess expert opinions, recommendations, surgical decision-making, and patient counseling for patients with high expectations for RTS after THA.

RESULTS

The majority of surgeons (81.9%) were in favor of RTS after THA. Risks associated with sports after THA were considered minimal (1%), with periprosthetic fractures ranking highest, followed by hip dislocation and polyethylene wear. Some surgical decision-making was influenced by high-RTS expectations in regard to implant fixation, stem type, femoral head diameter, and bearing-surface tribology. We observed an increasingly liberal counseling of patients for high-impact sports.

CONCLUSION

With the improvement of implants and surgical techniques, surgeons are more willing to encourage patients to adopt a more active lifestyle. However, the true long-term limitations need further investigation in future studies.

LEVEL OF EVIDENCE

5 Expert opinions.

Results of primary THA using 36 mm femoral heads on first-generation highly cross-linked polyethylene in patients less than 60 years of age: Minimum 10-year follow-ups

PURPOSE

Long-term results of total hip arthroplasty (THA) using highly cross-linked polyethylene (HXLPE) and metal femoral head with more than 10 years of follow-up have already been reported. However, most studies included results with a head size of 28 mm that could affect wear rates. The aim of this study was to evaluate the results of 36-mm metallic femoral heads on first-generation HXLPE in patients less than 60 years of age with a minimum follow-up of 10 years.

METHODS

Retrospective analysis included 54 cases from 47 patients. The mean age at the time of surgery was 47.22 years and the mean follow-up period was 131.04 months. Porous-coated cementless acetabular cups (Trilolgy®; Zimmer Inc., Warsaw, Indiana, USA) and HXLPE acetabular liners (Longevity®; Zimmer Inc.) were used for all cases. Acetabular cup abduction angles, anteversion angles, and wear rates of liner were measured using polyWare pro 3D distal version 5.10.

RESULTS

The average modified Harris hip score at the final follow-up was 88.48 (range 80-96). Average Merle d'Aubigne and Postel score was 15.57 (range 14-18). There was no acetabular cup or femoral stem failing due to aseptic loosening. The average steady-state wear rate determined using radiographs taken at 1 year postoperatively and at the latest follow-up was 0.053 ± 0.025 mm/year. There were no statistically significant differences in liner wear rate with respect to age, variety of the femoral stem, or liner thickness.

CONCLUSION

Results of THA with 36-mm metallic femoral heads on first-generation HXLPE in patients less than 60 years of age were satisfactory.

Adverse Local Tissue Reaction due to Acetabular Corrosion in Modular Dual-Mobility Constructs

Dual-mobility (DM) bearings in total hip arthroplasty (THA) have been reported to reduce dislocation rates, especially in high-risk patients, and are being rapidly adopted in primary and revision THAs. However, this technology introduces additional interfaces that have the potential to result in unforeseen complications. We present a series of 3 patients with mechanically assisted crevice corrosion at the acetabular component-metal dual-mobility liner interface. Consequently, we urge judicious use and close clinical observation of this new, effective technology in THA.

Are the Wear and Osteolysis Outcomes Different between Annealed and Remelted First-Generation Highly Crosslinked Polyethylene after Long-Term Implantation?

First-generation highly crosslinked polyethylene (HXLPE) was developed to reduce polyethylene wear debris and subsequent osteolysis. Two thermal stabilization strategies were developed, annealing and remelting, to remove free radicals remaining in the polymer. Both types of HXLPEs have demonstrated better wear resistance to conventional polyethylene in hip arthroplasty. However, few studies have directly compared the mid- to long-term clinical outcomes of first-generation HXLPEs. We sought to address the following research questions: (1) is there a difference between the revision reasons for HXLPE formulations (annealed and remelted), (2) is there a difference in oxidation between annealed and remelted HXLPEs, (3) is there a difference in the linear penetration rate of annealed and remelted HXLPEs, and (4) does the formulation of first-generation HXLPEs affect the prevalence of osteolysis? A total of 129 first-generation HXLPE acetabular liners were collected in a multicenter retrieval program. These components were implanted for 5 or more years and were fabricated from annealed or remelted HXLPE. Reasons for revision, body mass index, age, sex, and activity levels were collected from medical records. Oxidation was measured at four regions of interest: bearing surface, backside surface, locking mechanism, and rim. Liner penetration was directly measured from retrievals using a micrometer. Osteolysis was reported in the operative notes by the revising surgeon and a thorough review of the operative notes and radiographs. Revision reasons included infection, instability, pain, and loosening. The annealed liners had higher oxidation indices than remelted liners. There was no difference in linear penetration rates between cohorts. There was no difference in osteolysis prevalence between cohorts. We found remelted HXLPE to be more oxidatively stable than annealed HXLPE but did not find a significant difference in the linear penetration rates or the prevalence of osteolysis. Our findings demonstrate sustained long-term wear resistance of both cohorts of HXLPE. We did not find evidence to support a long-term clinical difference between the formulations of HXLPE.

Patient-Reported Outcomes and Perioperative Complications of Total Hip Arthroplasty Following Joint Preservation Surgery for Hip Dysplasia

BACKGROUND

There is growing recognition of the importance of patient-reported outcome measures and assessment of patient satisfaction in the evaluation of outcomes following surgical interventions. This study aimed to evaluate patient-reported outcomes and complication rates after total hip arthroplasty following joint preservation surgery for hip dysplasia.

METHODS

Patient-reported outcomes and complication rates of 85 hips with previous joint preservation surgery (salvage group) were compared with those of 1279 hips without joint preservation surgery (primary arthroplasty group). As a patient-reported outcome measure, the Japanese Orthopedic Association Hip Disease Evaluation Questionnaire was used to evaluate the hip condition both preoperatively and 12 months postoperatively. Operative data and postoperative (within 12 months) complications were investigated.

RESULTS

The salvage group had a longer operative time (56.8 vs 44.9 minutes, P < .001) and a higher total complication rate (5.9% vs 1.1%, P < .001). Additionally, the salvage group exhibited a lower degree of improvement in the visual analog scale value for satisfaction (75.1 vs 83.1 mm, P = .011), the pain and movement category scores, and the total score of the Japanese Orthopedic Association Hip Disease Evaluation Questionnaire (14.2 vs 16.2, P = .031; 13.7 vs 16.0, P = .005; and 42.3 vs 47.9, P = .007, respectively) compared with the primary arthroplasty group.

CONCLUSION

This study demonstrated a lower rate of improvement in patient satisfaction and worse self-reported outcomes in the salvage group. Furthermore, these patients had a longer operative time and a higher risk of operative complications.

Highly Cross-Linked Polyethylene in Cementless Total Hip Arthroplasty in Patients with Previous Acetabular Fractures: A Minimum 5-Year Follow-Up Study

BACKGROUND

Outcomes of THA after acetabular fracture are generally less favorable than those of the nontraumatic arthritis due to a higher rate of cup loosening and osteolysis. We, therefore, investigated whether highly cross-linked polyethylene liners positively impact outcomes of THA in patients with posttraumatic osteoarthritis after acetabular fracture.

METHODS

We retrospectively evaluated 39 patients with previous acetabular fracture who underwent THA using highly cross-linked polyethylene liner after a mean 8.5 year follow-up. All procedures were performed at a single institution by a single surgeon using the same type of THA implants. Wear measurements were performed using a computer-assisted PolyWare software. Osteolysis was evaluated with use of radiography and computed tomography.

RESULTS

The mean preoperative Harris hip score was 44.4 points, which improved to 93.1 points at final follow-up. Neither femoral nor acetabular components displayed mechanical loosening and no components had been revised. Radiographs and CT scans did not demonstrate osteolysis. The mean linear wear was 0.043 mm/y (range 0-0.098 mm/y). With the data available, univariate regression analysis suggests that age, gender, weight, initial fracture type, the duration of follow-up, activity level, liner thickness, acetabular cup inclination, and the necessity of bone graft had no influence on liner penetration.

CONCLUSION

While the long-term effects of the polyethylene particles from highly cross-linked polyethylene remain unknown, implant survivorship and wear data in this study are promising for this high-risk population. Our encouraging results support the continued use of this type of polyethylene in patients after acetabular fractures.

LEVEL OF EVIDENCE

Level IV Therapeutic study.

Long-term performance of oxidized zirconium on conventional and highly cross-linked polyethylene in total hip arthroplasty

Introduction: Polyethylene wear and subsequent osteolysis remain obstacles to the long-term survivorship of total hip arthroplasty (THA). Highly cross-linked polyethylene (XLPE) with radical quenching represents a massive leap forward with dramatically improved wear rates compared to ultra-high molecular weight polyethylene (UHMWPE). In this study we evaluate the wear of UHMWPE and XLPE coupled with oxidized zirconium (OxZr) femoral heads. Methods: A longitudinal, retrospective analysis was performed identifying consecutive patients who received a 28-mm OxZr-on-polyethylene primary THA from 2003 to 2004 by a single, high-volume arthroplasty surgeon. Patients were divided into two groups: those that received (1) UHMWPE liner and (2) a highly XLPE liner. Patients were included if clinical follow-up was complete to 2014 or later. Radiographic analysis was performed by two blinded observers. Measures included cup position, annual linear wear rate, and presence of osteolysis. Pairwise comparisons, correlations, and inter-rater reliability were calculated. Results: Eighty patients were in the UHMWPE group with an average follow-up of 10 ± 1.23 years and 88 patients in the XLPE group with an average of 10 ± 1.03-year follow-up. Average age (68) was similar between groups (p = 0.288). Observer reliability was excellent for cup abduction (ICC = 0.940), anteversion (ICC = 0.942), and detection of osteolysis (ICC = 0.811). Annual linear wear rates were significantly higher (p = 1 × 10⁻¹⁹) with UHMWPE (0.21 ± 0.12 mm/year) compared to XLPE (0.05 ± 0.03 mm/year). Linear wear rate was significantly correlated to decreasing acetabular abduction (p = 0.035). Osteolysis was noted only in the UHMWPE group, with 17 patients (21.2%) exhibiting acetabular osteolysis and 37 (46.3%) patients exhibiting femoral osteolysis. Conclusions: OxZr coupled with XLPE showed minimal wear and no osteolysis at 10-year follow up. The yearly linear penetration rate is similar to that seen in other studies of XLPE THA. A careful longitudinal follow-up will be required to determine if advanced bearings such as OxZr or ceramic can show improved performance in the second decade of implantation.

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

BACKGROUND

The 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).

METHODS

In 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.

RESULTS

Linear 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.

CONCLUSION

We suggest that elevated-rim highly cross-linked polyethylene acetabular liners might be a good implant option that can be used safely.

Primary Total Hip Arthroplasty in Patients 20 Years Old and Younger

BACKGROUND

Historically, total hip arthroplasty (THA) performed in patients ≤20 years old has been associated with poor survivorship because of bearing-surface wear with conventional polyethylene, acetabular loosening with cemented sockets, and liner fracture in ceramic-on-ceramic (CoC) THA. For this population, there is a paucity of data regarding outcomes of THAs performed with use of modern implants and bearing surfaces. The purpose of the present study was to examine the mid- to long-term outcomes of modern THA in patients ≤20 years old.

METHODS

Utilizing a single-institution, prospectively collected total joint registry, we retrospectively identified 91 primary THAs performed in 78 patients ≤20 years old from 1998 to 2016. The average patient age was 17 years (range, 11 to 20 years), and the average body mass index was 26 kg/m (range, 16 to 49 kg/m). Forty-eight THAs (53%) were performed in male patients, and 47 (52%) were performed on the right hip. Bearing surfaces included CoC (53 THAs, 58%), metal-on-highly cross-linked polyethylene (MoP; 28 THAs, 31%), and ceramic-on-highly cross-linked polyethylene (CoP; 10 THAs, 11%). Outcome measures included reoperations, revisions, complications, clinical outcome scores, and bearing-surface wear.

RESULTS

At an average follow-up of 8 years (range, 2 to 18 years), the average modified Harris hip score was 92 (range, 54 to 100), and 95% of patients reported feeling "much better" following the surgical procedure. Survivorship at 2, 5, and 10 years postoperatively was 96.7%, 96.7%, and 95.0% for reoperation; 98.9%, 98.9%, and 97.2% for revision; and 91.2%, 91.2%, and 89.5% for complications, respectively. The most common complications were instability (3 THAs, 3%), aseptic acetabular loosening (2 THAs, 2%), and postoperative foot drop (2 THAs, 2%). Linear articular wear averaged 0.019 mm/yr. There were no correlations between age, sex, body mass index, bearing surface, femoral head size, use of cement, or operative time and survivorship from complications, reoperations, or revisions. There were no differences in linear wear among CoC, CoP, and MoP bearing surfaces.

CONCLUSIONS

In patients ≤20 years old, THAs performed with use of modern implants exhibit excellent clinical outcome scores and survivorship at mid- to long-term follow-up. CoC, CoP, and MoP bearing surfaces have similar survivorship, clinical outcomes, and bearing-surface wear in this population.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Long-term outcomes of total hip arthroplasty in patients younger than 55 years: a systematic review of the contemporary literature

Background

Total hip arthroplasty (THA) is increasingly performed in younger patients despite the lack of comprehensive assessment of long-term outcomes. We systematically reviewed the contemporary literature to assess the 1) indications, 2) implant selection and long-term survivorship, 3) complication and reoperation rates and 4) radiographic and functional outcomes of primary THA in patients younger than 55 years.

Methods

We searched the Embase and MEDLINE databases for English-language articles published between 2000 and 2018 that reported outcomes of primary THA in patients younger than 55 years with a minimum follow-up duration of 10 years.

Results

Thirty-two studies reporting on 3219 THA procedures performed in 2434 patients met our inclusion criteria. The most common preoperative diagnoses were avascular necrosis (1044 [32.4%]), osteoarthritis (870 [27.0%]) and developmental dysplasia of the hip (627 [19.5%]). Modular implants (3001 [93.2%]), cementless fixation (2214 [68.8%]) and metal-on-polyethylene bearings (1792 [55.7%]) were frequently used. The mean 5- and 10-year survival rates were 98.7% and 94.6%, respectively. Data on survival beyond 10 years were heterogeneous, with values of 27%–99.5% at 10–14 years, 59%–84% at 15–19 years, 70%–77% at 20–24 years and 60% at 25–30 years. Rates of dislocation, deep infection and reoperation for any reason were 2.4%, 1.2% and 16.3%, respectively. The mean Harris Hip Score improved from 43.6/100 to 91.0/100.

Conclusion

Total hip arthroplasty in patients younger than 55 years provides reliable outcomes at up to 10 years. Future studies should evaluate the outcomes of THA in this population at 15–20 years’ follow-up.

Highly Cross-Linked Polyethylene in Total Hip Arthroplasty in Patients Younger Than 50 Years With Osteonecrosis of the Femoral Head: A Minimum of 10 Years of Follow-Up

BACKGROUND

Polyethylene wear and subsequent periprosthetic osteolysis remain a major concern of total hip arthroplasty (THA) failure in young, active patients with osteonecrosis of the femoral head (ONFH). The literature is lacking regarding the long-term performance of highly cross-linked polyethylene (HXLPE) in these patients. The purpose of this study is to evaluate long-term results for cementless THA using metal-on-HXLPE bearing couplings in patients younger than 50 years with ONFH.

METHODS

We retrospectively evaluated the clinical and radiographic results of a consecutive series of 85 THAs (in 67 patients) performed with HXLPE liners (Durasul) in patients younger than 50 years who had ONFH. All procedures were performed at a single institution by a single surgeon using the same type of implants. The minimum duration of follow-up was 10 years (mean, 13.5 years; range, 10-17.3 years). Wear was measured using computer software. Osteolysis was evaluated with the use of radiography and computed tomography.

RESULTS

The mean Harris hip score was 49.3 points (range, 26-68 points) before surgery, which improved to 93.6 points (range, 87-98 points) after surgery. Neither femoral nor acetabular components displayed mechanical loosening, and no components had been revised by the final follow-up evaluation. Radiographs and computed tomography scans did not demonstrate osteolysis. The mean liner wear was 0.037 mm/y (range, 0-0.099 mm/y). With the data available, univariate regression analysis did not demonstrate that age, sex, weight, activity level, underlying cause of osteonecrosis, liner thickness, or cup inclination had any influence on liner penetration.

CONCLUSION

Although the long-term effects of HXLPE particles remain unknown, the implant survivorship rate and wear rate in our study are promising and support the continued use of metal-on-HXLPE bearing couplings in these high-risk patients because they do not produce any of the issues associated with hard-on-hard couplings.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

High survivorship of highly cross-linked polyethylene in revision Total hip Arthroplasty: a minimum 10-year follow-up study

Purpose

Highly cross-linked polyethylene has been introduced to decrease osteolysis secondary to polyethylene wear debris generation. However, few long-term data on revision total hip arthroplasty (THA) using highly cross-linked polyethylene liners are available. The objective of this study was to determine long-term outcomes of a highly cross-linked polyethylene liner in revision THA.

Materials & methods

We evaluated 63 revision THAs performed in 63 patients using a highly cross-linked polyethylene liner between April 2000 and February 2005. Of these, nine died and four were lost to follow-up. Thus, the final study cohort consisted of 50 patients (50 hips), including 26 males and 24 females with a mean age of 53 years (range, 27–75 years). Mean follow-up was 11 years (range, 10–14 years).

Results

The mean Harris hip score improved from 44 points preoperatively to 85 points at the final follow-up. No radiographic evidence of osteolysis was found in any hip. The mean rate of polyethylene liner wear was 0.029 mm/year (range, 0.003 to 0.098 mm/year). A total of 5 hips (10%) required re-revision arthroplasty, including one cup loosening, one recurrent dislocation, and three deep infections. Kaplan-Meier survivorship with an end point of re-revision for any reason was 91.1% and for aseptic cup loosening was 97.9% at 11 years.

Conclusion

At a minimum of 10 years, the highly cross-linked polyethylene liners showed excellent clinical performance and implant survivorship, and were not associated with osteolysis in our patients with revision THAs.

Titanium acetabular cementless cups combined with highly crosslinked polyethylene liner have very low rates of aseptic loosening

BACKGROUND

There is a clear tendency towards cementless acetabular components in primary total hip arthroplasty.

OBJECTIVE

The aim of this study was to assess the long-term clinical and radiological outcome of titanium cementless acetabular cups when combined with a highly crosslinked polyethylene liner.

METHODS

This study is a retrospective follow-up of 67 cups in 64 patients. Clinical outcomes were assessed using the Harris Hip Score. Radiolucent lines, osteolysis and loosening were assessed radiologically. Implant survival was determined using the Kaplan-Meier analysis.

RESULTS

The average Harris Hip Score at follow-up was 80.3 ± 14.5. Signs of osteolysis were observed in 7.1% of the radiographs. No aseptic loosening of the cup was reported. Survival of the cup with aseptic loosening as an endpoint was 100%. A comparison with 19 other studies using the same material combination demonstrated very similar results. All manufacturers with available studies have at least one report of 100% survivorship at 10-year follow-up for their titanium cup and highly crosslinked polyethylene acetabular component combination with aseptic loosening as an endpoint.

CONCLUSIONS

The data suggests that the rate of aseptic loosening of a titanium cup combined with a highly-crosslinked polyethylene liner at 10-year follow-up could be as low as 0%.

Biaxial fatigue crack propagation behavior of ultrahigh molecular weight polyethylene reinforced by carbon nanofibers and hydroxyapatite

Ultrahigh molecular weight polyethylene (UHMWPE) artificial joint has remained the preferred polymer component in total joint replacement surgery. However, more and more concerns have been raised about the failure of UHMWPE components due to the initiation and propagation of cracks at the notches with fixed functions. For this reason, biaxial fatigue crack growth (FCG) experiments of UHMWPE reinforced by carbon nanofibers (CNF) and hydroxyapatite (HA) were carried out using elastic-plastic fracture mechanics theory. The FCG resistance of UHMWPE, UHMWPE/CNF, and UHMWPE/HA was compared, and the effects of stress ratio (R) value and phase difference on FCG rate were investigated. At the same time, the influence of loading path was considered, and the corresponding crack path was analyzed. Results suggest that UHMWPE/CNF has better FCG resistance and the FCG rate increases with the increase of R value and the existence of 180° phase difference. In addition, crack bifurcation behavior is not observed under nonproportional loading conditions. The findings in this study will provide experimental validation and data support for better clinical application of UHMWPE-modified materials.

A Comparison Study of the Outcomes of Ceramic-on-Ceramic Total Hip Arthroplasty in Young vs Older Patients: A Minimum 10-Year Follow-Up Prospective Matched Study

BACKGROUND

The purpose of this study is to analyze the outcome and prosthesis survival in patients aged between 20 and 40 years who received a cementless total hip arthroplasty (THA) with a minimum follow-up of 10 years compared to older patients.

METHODS

Prospective matched comparative study was conducted between 94 young patients with mean age of 37.2 (range 22-40) years and 90 older patients with mean age of 64.7 (range 60-70) years treated with ceramic-on-ceramic THA. Clinical outcomes were assessed by the Harris Hip Score, reduced Western Ontario and MacMaster University (WOMAC), and Short-Form-12 (SF12) questionnaires. Radiological evaluation was also performed. The primary outcome was the THA survival rate.

RESULTS

Mean follow-up of 13.6 (range, 10-15) years. At the final follow-up, there was no significant difference between groups in Harris Hip Score (P = .356), WOMAC-pain (P = .461), SF12-physical (P = .305), or SF12-mental (P = .511), but younger group had significantly higher WOMAC-function score (P = .013). There were 7 revisions in the younger group and 4 in the older group (P = .197). The 14-year prosthesis survival for any reason was 93.2% (95% confidence interval [CI] 86.7-99.7) in the younger group and 98.3% (95% CI 95.1-100) in the older group (P = .189). For aseptic reason, the 14-year survival was 94.7% (95% CI 88.9-100) in the younger group and 98.3% (95% CI 95.1-100) in the older group (P = .332).

CONCLUSION

At minimum follow-up of 10 years, THA with cementless stem and ceramic-on-ceramic bearing provides successful survival and functional outcomes in young patients between 20 and 40 years old.

Comparison of Intermediate-Term Outcomes of Total Ankle Arthroplasty in Patients Younger and Older Than 55 Years

BACKGROUND

Total ankle arthroplasty is often not recommended to younger patients with ankle arthritis because of their high functional demands. The purpose of this study was to compare intermediate-term clinical and radiographic outcomes and survivorship rates of total ankle arthroplasty between patients younger and older than 55 years.

METHODS

A total of 117 consecutive patients (123 ankles) who underwent primary total ankle arthroplasty using Hintegra prosthesis with a mean follow-up of 78 months were enrolled and divided into 2 age groups: under 55 years (38 ankles; mean age 45 years) and over 55 years (85 ankles; mean age 65 years).

RESULTS

Clinical scores of Ankle Osteoarthritis Scale pain and disability, American Orthopaedic Foot & Ankle Society ankle-hindfoot, Short Form-36 Physical Component Summary and Mental Component Summary, and visual analog scale were not significantly different between the 2 age groups at the final follow-up (P > .05). There were no significant differences in complications and survivorship rates between the two at a mean follow-up of 78 months (P > .05).

CONCLUSIONS

Clinical and radiographic outcomes and survival rates of total ankle arthroplasty in patients under age of 55 years were satisfactory and comparable to those in patients older than 55 years in the intermediate-term follow-up. Therefore, total ankle arthroplasty may be considered as a viable treatment option in young patients with end-stage ankle arthritis.

LEVEL OF EVIDENCE

Level III, comparative series, therapeutic.

Primary Total Hip Arthroplasty in Patients Less Than 50 Years of Age at a Mean of 16 Years: Highly Crosslinked Polyethylene Significantly Reduces the Risk of Revision

BACKGROUND

The purpose of this study is to evaluate clinical and radiographic outcomes of patients less than 50 years of age undergoing primary total hip arthroplasty (THA) at a minimum of 10 years.

METHODS

Three hundred nine consecutive THAs performed on 273 patients were reviewed. At a minimum of 10 years, 13 were deceased and 23 were lost to follow-up leaving 273 THAs in 237 patients who were followed for a mean of 16 years (range 10-19.9). The cohort consisted of 116 females (49%) and 121 males (51%), with a mean age of 42.3 years at the time of surgery (range 19-49). The majority of preoperative diagnoses included osteoarthritis in 149 (63%) and avascular necrosis in 55 (23%). Two hundred sixteen had highly crosslinked polyethylene (HXLPE) and 57 had non-HXLPE acetabular liners. The femoral stems were cementless in 98% (266/273) and the acetabular components were cementless in all cases. Femoral head composition was cobalt-chromium in all cases and the majority of sizes in the non-HXLPE cohort were 28 mm (52/57; 91%), while the HXLPE group primarily consisted of 28 mm (141/216; 65%) and 32 mm (74/216; 34%) heads. Analysis involved Kaplan-Meier survivorship with a log-rank test for equivalence, Fisher's exact test for pairwise comparisons, and a paired t-test for Harris Hip Score, with alpha = 0.05 being statistically significant.

RESULTS

There were 6 revisions for wear in the non-HXLPE group (10.5%) compared to none in the HXLPE group (P < .001). Similarly, survivorship with revision for any reason as the endpoint at 16 years was significantly higher at 93.0% in the XLPE group (95% confidence interval 88.7-95.7) compared to 85.7% (95% confidence interval 73.5-92.6) in the non-HXLPE group (P = .023). Additional revisions in the HXLPE group included 6 for instability (2.8%), 5 secondary to infection (2.4%), and 3 stem failures (1.4%). Non-wear-related revisions in the non-HXLPE group included 5 due to instability (8.8%) and 3 due to stem failures (5.3%). The mean Harris Hip Scores for the entire cohort improved from a mean of 46.2 points preoperatively to 89.8 points at most recent follow-up (P < .001).

CONCLUSION

The use of HXLPE has led to a significant reduction in the risk of failure in patients <50 years old, with over 93% survivorship at 16 years. Instability and infection, however, remain substantial causes of failure.

LEVEL OF EVIDENCE

Therapeutic Level III.

Causes of Revision in Young Patients Undergoing Total Hip Arthroplasty

BACKGROUND

The purpose of this study was to identify reasons for revision of total hip arthroplasty (THA) in patients who underwent primary THA at or before the age of 35 years. We hypothesized that the reasons for revision in younger patients would be different from the general older population of patients undergoing THA because of the differences in diagnoses, complexity of deformities, and differences in activity level.

METHODS

Data for 108 hips in 82 patients who underwent primary THA at our institution before the age of 35 years from 1982-2007 and subsequently underwent revision THA were reviewed. Operative reports and clinic notes were reviewed to determine baseline characteristics, reason for revision, timing of revision, and components revised.

RESULTS

The mean age at index surgery was 25.4 years, and mean time from index to revision surgery was 10.1 years. The most common preoperative diagnoses included avascular necrosis, juvenile idiopathic arthritis, developmental dysplasia of the hip, and posttraumatic arthritis. The most common reasons for revision were acetabular loosening (30.1%), femoral loosening (23.7%), and polyethylene wear (24.7%). 8.3% of patients underwent primary THA with highly cross-linked polyethylene, while the remainder of the patients underwent THA when conventional polyethylene was used. There was no statistically significant association between which component(s) were revised and initial fixation (ie cemented or uncemented prosthesis) (P = .26).

CONCLUSION

Causes of revision in this population appear to differ from the general THA population. In young patients, acetabular loosening, femur loosening, and polyethylene wear were the most common causes of revision. Instability and infection were less common compared with literature reports of causes of revision in older patients. Findings in this study may be useful in counseling young patients undergoing THA, though results were likely influenced by the use of conventional rather than highly cross-linked polyethylene in this cohort.

Femoral Head Penetration Rates of Second-Generation Sequentially Annealed Highly Cross-Linked Polyethylene at Minimum Five Years

BACKGROUND

Highly cross-linked polyethylene (HXLPE) liners in total hip arthroplasty (THA) have demonstrated decreased wear rates, resilience to cup orientation, and reduced osteolysis compared to conventional polyethylene. Sequential irradiation and annealing below the melting temperature is unique compared to most HXLPE which is irradiated and remelted. This study purpose is to provide minimum 5-year femoral head penetration rates of sequentially annealed HXLPE in primary THA.

METHODS

A retrospective review of a prospectively collected database identified 198 consecutive, cementless primary THAs utilizing sequentially annealed HXLPE (X3; Stryker, Mahwah, NJ). Operative technique was standardized. Radiographs were analyzed utilizing the Martell method with minimum 5-year and 1-year radiographs as baseline to minimize the initial bedding-in period.

RESULTS

Seventy-seven hips with minimum 5-year follow-up were analyzed. Mean steady state linear and volumetric head penetration rates were 0.095 mm/y and 76 mm³/y, respectively. Volumetric head penetration was significantly less for 32-mm compared to 36-mm (P = .028). In addition, less head penetration was observed for ceramic 32-mm heads at nearly half the rate compared to cobalt-chromium 36-mm heads (P ≥ .092). No correlations existed between penetration rates and age, body mass index, University of California Los Angeles Activity Level, polyethylene thickness, cup inclination, or anteversion (P ≥ .10). No radiographic osteolysis was observed.

CONCLUSION

Surprisingly, linear head penetration rates of sequentially annealed HXLPE were nearly identical to the osteolysis threshold for conventional polyethylene and greater than reports of irradiated and remelted HXLPE. Furthermore, these data corroborate reports that HXLPE is resilient to cup orientation and demographic variables. Longer term follow-up is recommended.

Crack initiation from a clinically relevant notch in a highly-crosslinked UHMWPE subjected to static and cyclic loading

Crosslinked Ultra High Molecular Weight Polyethylene (UHMWPE), which is used as a bearing material in total joint replacement components, is subjected to static and cyclic loads in vivo. Resistance to crack initiation from a notch as a function of static and cyclic loads is not well understood for crosslinked UHMWPE. This study estimated the resistance of crosslinked UHMWPE (crosslinked with 100 kGy gamma radiation and remelted to extinguish free radicals) to crack initiation for a clinically relevant notch under both static and cyclic loading conditions. For cyclic loading, four frequencies were applied with a sine waveform and two frequencies were applied with a square waveform to independently estimate the effect of frequency and rate of loading on crack initiation. Crack initiation time and cycles to crack initiation were determined. Crack initiation time for fatigue loading conditions was substantially lower compared to static loading conditions. Crack initiation time decreased with an increase in test frequency. A square wave resulted in shorter crack initiation time compared to a sine wave. The results suggest that crosslinked UHMWPE is more resistant to crack initiation from a notch under static loading conditions compared to fatigue loading conditions.

Manufacturing, oxidation, mechanical properties and clinical performance of highly cross-linked polyethylene in total hip arthroplasty

Ultra-high molecular weight polyethylene (UHMWPE) continues to be the gold standard bearing surface in total hip arthroplasty (THA) for nearly 5 decades. Highly cross-linked UHMWPE (HXLPE) was adapted for routine use in the early 2000s to reduce the revision rates related to wear, osteolysis, and aseptic loosening resulting from conventional UHMWPE wear. Since its inception, consistent evidence showing reduced wear rates and osteolysis supports the use of HXLPE in THA. High quality studies demonstrating the advantage in long term survivorship of HXLPE over conventional UHMWPE are emerging. Though retrieval studies have demonstrated evidence of in vivo oxidation and fatigue related damage at the rim of the first generation HXLPE liners, clinical significance of this remains to be seen. Second-generation sequentially annealed and vitamin E containing HXLPE liners demonstrate improved mechanical properties, resistance to oxidation, and equivalent wear rates in comparison to their first-generation counterparts, but long term success remains to be seen.

Developmental Dysplasia Treated With Cementless Total Hip Arthroplasty Utilizing High Hip Center Reconstruction: A Minimum 13-Year Follow-up Study

BACKGROUND

The primary aim of this study was to determine the clinical outcomes at 13-year follow-up of patients diagnosed with developmental dysplasia of the hip and subsequently treated with total hip arthroplasty (THA). The secondary aim was to investigate the effect of hip center location on clinical outcomes and polyethylene wear.

METHODS

We reviewed data from a consecutive series of 104 patients (123 hips) from a single center. Patients were treated with THA with the high hip center (HHC) technique using cementless acetabular shells and highly cross-linked liners. Radiographs were collected preoperatively and through 13-year follow-up to assess degree of dysplasia (Crowe classification), component positioning, occurrence of bone resorption, and polyethylene wear. The Harris Hip Score (HHS) was administered at 4 and 13 years.

RESULTS

No patients were lost to follow-up, and one was revised for femoral loosening. Radiolucency was seen in 20% of patients and was not associated with HHC (P = .560). No patients developed osteolysis. The wear rate was low for all patients (mean: 3 ± 19 μm/y) and not associated with HHC (P = .852). The median 13-year HHS was 91.9 (interquartile range: 84.8-97.0). There was a statistically significant decline from the 4- to 13-year HHS (P < .001) for the Crowe II-IV group, although 82% of these patients remained above 80 points at 13 years. The nondysplastic and Crowe I group showed no longitudinal change in HHS (P = .243).

CONCLUSION

This cup design and highly cross-linked polyethylene liner combination demonstrates excellent clinical outcomes, similar to THA for primary osteoarthritis, through 13-year follow-up in patients with various degrees of developmental dysplasia of the hip and HHC reconstructions.

Fresh Osteochondral Allograft Transplantation for Treatment of Large Cartilage Defects of the Femoral Head: A Minimum Two-Year Follow-Up Study of Twenty-Two Patients

BACKGROUND

Controversy remains over the surgical management of large osteochondral lesions of the femoral head in young, active patients. The purpose of this study is to assess midterm clinical and radiographic outcomes after fresh osteochondral allograft transplantation (OAT) for large femoral head lesions at minimum 2-year follow-up.

METHODS

A retrospective review of prospectively collected data was performed for 22 patients under the age of 50 years with defined femoral head osteochondral lesions who underwent fresh OAT between 2008 and 2015. Patients were assessed clinically using the modified Harris Hip Score (mHHS) preoperatively and at each follow-up visit. Postoperative radiographs were evaluated for graft integrity and Kellgren & Lawrence Grade for osteoarthritis severity. Complications and reoperation were assessed by chart review. Kaplan-Meier survivorship analyses with 95% confidence intervals were performed for the end point of conversion to total hip arthroplasty.

RESULTS

At a mean follow-up of 68.8 months (26-113), the mean mHHS improved significantly (P < .001) from 48.9 (19-84) to 77.4 (35-98). Sixteen of 22 patients (72.7%) had an mHHS ≥70 at the latest follow-up. Arthritic progression, as indicated by an increase in the Kellgren & Lawrence Grade, occurred in 4 of 22 hips (18.2%). Five patients (22.7%) underwent conversion to total hip arthroplasty. Graft survivorship was 86.4 ± 7.3% at 2 years, 78.5 ± 10.0% at 5 years, and 67.3 ± 13.5% at 9 years.

CONCLUSION

Fresh OAT may be a viable treatment option for osteochondral defects of the femoral head in young, active patients with minimal preexisting joint deformity.

Wear performance of cobalt chromium, ceramic, and oxidized zirconium on highly crosslinked polyethylene at mid-term follow-up

Patients with THA using a ceramic head and using an OxZr head were each matched to patients with a CoCr head. Mean implantation time was 5 years. There was no difference in steady state wear rate between the ceramic (0.066 ± 0.050 mm/year) and CoCr match groups (0.052 ± 0.041 mm/year), or between the OxZr (0.022 ± 0.029 mm/year) and CoCr match groups (0.048 ± 0.071 mm/year). Follow-up into the second decade will be necessary before any changes in THA wear rate from using ceramic or OxZr bearings may be appreciated clinically with available imaging techniques.

Otto Aufranc Award: Crosslinking Reduces THA Wear, Osteolysis, and Revision Rates at 15-year Followup Compared With Noncrosslinked Polyethylene

BACKGROUND

Crosslinked polyethylene (XLPE) liners used for primary THA have demonstrated lower wear rates than noncrosslinked, conventional polyethylene (CPE) liners through the first decade of clinical service. However, little high-quality evidence is currently available regarding the second decade performance of these implants and it remains uncertain whether the onset of osteolysis has simply been delayed or if the wear associated with XLPE liners will remain low enough that osteolysis will not occur. It is also unknown how the potential reductions in wear and osteolysis will influence long-term revision rates.

QUESTIONS/PURPOSES

Do patients who underwent THA with XLPE liners demonstrate (1) a lower rate of revision for wear-related complications; (2) a reduced wear rate; and (3) a lower frequency of osteolysis compared with those with CPE liners?

METHODS

Over an 18-month period from 1999 to 2000, 226 patients who had 236 primary THAs consented to participate in a randomized controlled trial conducted at one institution. To be eligible for intraoperative randomization, patients had to be implanted with a 28-mm cobalt-chrome alloy femoral head, a 4-mm lateralized liner, and the same cup and stem design. Six patients with six THAs were excluded intraoperatively because they did not receive study components for reasons unrelated to the liner material. The remaining 230 THAs among 220 patients were randomized to XLPE liners or CPE liners. The mean age at surgery was 62 ± 11 years and there were no differences in age, gender, or body mass index among the groups. There was no differential loss to followup between the study groups; among patients not known to be deceased or having undergone revision, minimum 14-year radiographic followup is available for 85 THAs including 46 with XLPE and 39 with CPE liners. Polyethylene wear was measured radiographically using Martell's Hip Analysis Suite and areas of osteolysis were evaluated before revision or at most recent followup. Revision rates at 15 years using reoperation for any reason and revision for wear or osteolysis were calculated using cumulative incidence considering patient death as a competing risk.

RESULTS

The cumulative incidence of revision at 15 years using reoperation for wear-related complications as an endpoint was lower in the XLPE group than the CPE group (0%, 95% confidence interval [CI], 0%-0% versus 12%, 95% CI, 7%-19%; p < 0.001). Among unrevised THAs with minimum 14-year radiographic followup, the mean steady-state linear wear rate for THAs with XLPE liners was lower than the mean linear wear rate for the THAs with CPE liners (0.03 ± 0.05 versus 0.17 ± 0.09 mm/year; mean difference, 0.14; 95% CI, 0.11-0.17; p < 0.001). Osteolysis of any size was noted among 9% (four of 46) of the hips in the XLPE group and 46% (18 of 39) of the hips in the CPE group (odds ratio, 0.19; 95% CI, 0.07-0.51; p < 0.001).

CONCLUSIONS

This randomized study with followup into the second decade demonstrated reductions in revision, wear, and osteolysis associated with the use of XLPE. The low wear rates and absence of any mechanical failures among the XLPE liners at long-term followup affirm the durability of these components that did not incorporate antioxidants. Although osteolysis has not been eliminated, it occurs infrequently and has not caused any clinical problems to date.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Bearing Surfaces for Total Hip Arthroplasty

Metal-on-highly cross-linked polyethylene is considered the preferred bearing surface for conventional total hip arthroplasty because of its safety profile and excellent results in the first 10 to 15 years of use. However, with younger patient age, activity expectations increase, and the life expectancy of patients with total hip arthroplasty also has increased, so interest remains in other bearing couples. These other options include the use of various ceramic composites for the femoral head on highly cross-linked polyethylene, the so-called second-generation antioxidant polyethylenes, and ceramic acetabular liners. Several of these bearing couples have shown excellent wear rates in vitro, and short-term clinical studies have demonstrated favorable wear and safety results. It is uncertain whether any of these bearing couples should be adopted at present. Understanding the unique properties and possible complications of these bearing couples is critical for appropriate implant selection.