Hip resurfacing and osteonecrosis: results from an independent hip resurfacing register

Evaluating the Use of PROMs in Paediatric Orthopaedic Registries

Patient-reported outcome measures (PROMs) provide structured information on the patient's health experience and facilitate shared clinical decision-making. Registries that collect PROMs generate essential information about the clinical course and efficacy of interventions. Whilst PROMs are increasingly being used in adult orthopaedic registries, their use in paediatric orthopaedic registries is not well known. The purpose of this systematic review was to identify the frequency and scope of registries that collect PROMs in paediatric orthopaedic patient groups. In July 2023, six databases were systematically searched to identify studies that collected PROMs using a registry amongst patients aged under 18 years with orthopaedic diagnoses. Of 3190 identified articles, 128 unique registries were identified. Three were exclusively paediatric, 27 were majority paediatric, and the remainder included a minority of paediatric patients. One hundred and twenty-eight registries collected 72 different PROMs, and 58% of these PROMs were not validated for a paediatric population. The largest group of orthopaedic registries collected PROMs on knee ligament injuries (21%). There are few reported dedicated orthopaedic registries collecting PROMs in paediatric populations. The majority of PROMs collected amongst paediatric populations by orthopaedic registries are not validated for patients under the age of 18 years. The use of non-validated PROMs by registries greatly impedes their utility and impact. Dedicated orthopaedic registries collecting paediatric-validated PROMs are needed to increase health knowledge, improve decision-making between patients and healthcare providers, and optimise orthopaedic management.

Hip resurfacing for small-sized osteonecrosis: 73 cases at a median 8years' follow-up

INTRODUCTION

Total hip resurfacing arthroplasty (THRA) is an alternative to conventional total hip replacement (THR) in young patients with osteonecrosis of the femoral head. Series have been small, without criteria regarding extent of necrosis, thus vitiating results. We therefore conducted a retrospective assessment of THRA for small necrosis, to determine (1) implant survival, (2) functional scores, and (3) systemic chromium, cobalt and titanium ion concentrations.

HYPOTHESIS

The study hypothesis was that the revision rate is low, meeting the National Institute for Health and Care Excellence (NICE) criterion of<0.5% revision per year.

MATERIAL AND METHOD

A single-center single-surgeon retrospective study included 62 patients, for 73 RTHAs, with a mean age of 45.6years (range: 23-68years) presenting Ficat stage 3 or 4 osteonecrosis of the femoral head with<330° total Kerboul angle (frontal+lateral angles) on simple preoperative X-ray. Study data comprised implant survival and preoperative and last follow-up functional scores (Postel-Merle-d'Aubigné, Oxford-12, Harris, and Devane) and titanium, chromium and cobalt blood concentrations. Necrosis size was assessed on preoperative Kerboul angle.

RESULTS

At a median 8years' follow-up (IQR: 5.9-9.3years), implant survival was 98.6% (95% CI: 97.22-99.98%). Only 1 implant was exchanged, for femoral loosening. Three other patients underwent revision surgery: 2 cases of lavage for infection, and 1 muscle hernia repair. Postel-Merle-d'Aubigné, Oxford-12 and Harris functional scores and Devane activity scores were significantly improved at follow-up, by a median +5 (IQR: 5 to 7), -26 (IQR: -29 to -23), +55 (IQR: 49 to 61) and +1 (IQR: 1 to 2), respectively (all p<0.001). Ion concentrations at last follow-up for titanium, chromium and cobalt were respectively 4.0μg/L (range: 3.6-4.1), 1.1μg/L (range: 0.8-1.9) and 1.1μg/L (range: 0.6-1.8).

CONCLUSION

THRA is a useful option in the long-term for young patients with osteonecrosis with Kerboul angle<330°.

LEVEL OF EVIDENCE

IV, retrospective study.

Hip resurfacing arthroplasty for osteonecrosis of the femoral head: Implant-specific outcomes and risk factors for failure

Background

Hip resurfacing arthroplasty (HRA) may be a suitable option for treating osteonecrosis of the femoral head (ONFH). However, concerns regarding the extent of osteonecrosis, amount of defect under the prosthesis, and implant-related complications remain. This study aimed to report implant-specific outcomes and risk factors for failure of HRA in ONFH.

Methods

A total of 202 HRAs (166 patients) performed by a single surgeon were investigated. The stage, size, and location of ONFH were evaluated using preoperative radiographs and magnetic resonance images. Clinical, radiographic results, and serum metal concentrations of articular surface replacement (ASR) and non-ASR devices were compared. Logistic regression analysis was performed to identify the contributors of failures. The mean follow-up duration was 10.6 years.

Results

Twenty-six hips (12.9%) were operated with Birmingham Hip Resurfacing (BHR), 99 (49.0%) with ASR, and 77 (38.1%) with Conserve Plus. The mean Harris Hip Score improved from 52.1 to 93.2 at the final follow-up (P < 0.001). Revision-free survivorships of non-ASR and ASR implants were 99.0% and 82.4%, respectively (P < 0.001). In multivariate analysis, the use of ASR prosthesis, greater combined necrotic angle, and smaller head size were associated with revision surgery. A large combined necrotic angle was the only independent risk factor for mechanical failure at the femoral side (P = 0.029).

Conclusion

HRA for ONFH using BHR and Conserve Plus implants demonstrated favourable clinical outcomes with high revision-free survival rates at 10 years. However, care should be taken for large necrotic lesions that can lead to femoral neck fracture or aseptic femoral loosening.

The translational potential of this article

This study suggests HRA performed for appropriately selected patients with ONFH can show excellent long-term clinical results. Therefore, HRA should remain as one of the treatment options for ONFH, and further development of HRA implants should be continued.

First Biomimetic Fixation for Resurfacing Arthroplasty: Investigation in Swine of a Prototype Partial Knee Endoprosthesis

Resurfacing hip and knee endoprostheses are generally embedded in shallow, prepared areas in the bone and secured with cement. Massive cement penetration into periarticular bone, although it provides sufficient primary fixation, leads to the progressive weakening of peri-implant bone and results in failures. The aim of this paper was to investigate in an animal model the first biomimetic fixation of components of resurfacing arthroplasty endoprostheses by means of the innovative multispiked connecting scaffold (MSC-Scaffold). The partial resurfacing knee arthroplasty (RKA) endoprosthesis working prototype with the MSC-Scaffold was designed for biomimetic fixation investigations using reverse engineering methods and manufactured by selective laser melting. After Ca-P surface modification of bone contacting surfaces of the MSC-Scaffold, the working prototypes were implanted in 10 swines. Radiological, histopathological, and micro-CT examinations were performed on retrieved bone-implant specimens. Clinical examination confirmed very good stability (4 in 5-point Likert scale) of the operated knee joints. Radiological examinations showed good implant fixation (radiolucency less than 2 mm) without any signs of migration. Spaces between the MSC-Scaffold spikes were penetrated by bone tissue. The histological sections showed newly formed trabecular bone tissue between the spikes, and the trabeculae of periscaffold bone were seen in contact with the spikes. The micro-CT results showed the highest percentage of bone tissue ingrowths into the MSC-Scaffold at a distance of 2.5÷3.0 mm from the spikes bases. The first biomimetic fixation for resurfacing arthroplasty was successfully verified in 10 swines investigations using RKA endoprosthesis working prototypes. The performed research shows that the MSC-Scaffold allows for cementless and biomimetic fixation of resurfacing endoprosthesis components in periarticular cancellous bone.

An evidence-based guide to the treatment of osteonecrosis of the femoral head

Non-traumatic osteonecrosis of the femoral head is a potentially devastating condition, the prevalence of which is increasing. Many joint-preserving forms of treatment, both medical and surgical, have been developed in an attempt to slow or reverse its progression, as it usually affects young patients. However, it is important to evaluate the best evidence that is available for the many forms of treatment considering the variation in the demographics of the patients, the methodology and the outcomes in the studies that have been published, so that it can be used effectively. The purpose of this review, therefore, was to provide an up-to-date, evidence-based guide to the management, both non-operative and operative, of non-traumatic osteonecrosis of the femoral head. Cite this article: Bone Joint J 2017;99-B:1267-79.

Comparison of Cemented and Bone Ingrowth Fixation Methods in Hip Resurfacing for Osteonecrosis

BACKGROUND

The optimal surgical treatment for osteonecrosis of the femoral head has yet to be elucidated. To evaluate the role of femoral fixation techniques in hip resurfacing, we present a comparison of the results for 2 consecutive groups: group 1 (75 hips) received hybrid hip resurfacing implants with a cemented femoral component; group 2 (103 hips) received uncemented femoral components. Both groups received uncemented acetabular components.

METHODS

We retrospectively analyzed our clinical database to compare failures, reoperations, complications, clinical results, metal ion test results, and X-ray measurements. Using consecutive groups caused time interval bias, so we required all group 2 patients to be at least 2 years out from surgery; we compared results from 2 years and final follow-up.

RESULTS

Patient groups matched similarly in age, body mass index, and percent female. Despite similar demographics, the uncemented, group 2 cases showed a lower raw failure rate (0% vs 16%; P < .0001), a lower 2-year failure rate (0% vs 7%; P = .04), and a superior 8-year implant survivorship (100% vs 91%; log-rank P = .0028; Wilcoxon P = .0026). In cases that did not fail, patient clinical (P = .05), activity (P = .02), and pain scores (P = .03), as well as acetabular component position (P < .0001), all improved in group 2, suggesting advancements in surgical management. There were no cases of adverse wear-related failure in either group.

CONCLUSION

This study demonstrates a superior outcome for cases of osteonecrosis with uncemented hip resurfacings compared to cases employing hybrid devices.

Hip resurfacing for osteonecrosis

Aims

Hip resurfacing arthroplasty (HRA) is an alternative to conventional total hip arthroplasty for patients with osteonecrosis (ON) of the femoral head. Our aim was to report the long-term outcome of HRA, which is not currently known.

Patients and Methods

Long-term survivorship, clinical scores and radiographic results for 82 patients (99 hips) treated with HRA for ON over a period of 18 years were reviewed retrospectively. The mean age of the 67 men and 15 women at the time of surgery was 40.8 years (14 to 64). Patients were resurfaced regardless of the size of the osteonecrotic lesion.

Results

The mean clinical follow-up was 10.8 years (2 to 18). The mean University of California, Los Angeles hip scores at the last follow-up were 9.3, 9.4, 9.2 and 6.8 for pain, walking, function and activity, respectively. A total of six hips underwent revision surgery, four for loosening of the femoral component and two for loosening of the acetabular component. Using any revision as an end point, the 15-year Kaplan-Meier survivorship was 90.3%. There were no wear-related failures. There were no femoral failures among the hips reconstructed with a cemented metaphyseal stem. A total of five hips showed narrowing of the femoral neck; all stabilised and remain asymptomatic, 21 showed signs of femoral neck impingement.

Conclusion

To our knowledge, this is the first report of a series of HRA performed for ON with 15-year survivorship. Our data confirm that patients with advanced stages of ON of the femoral head are excellent candidates for HRA. Cite this article: Bone Joint J 2016;98-B:901–9.

Hip arthroplasty for treatment of advanced osteonecrosis: comprehensive review of implant options, outcomes and complications

Surgical treatment for late stage (post-collapse) osteonecrosis of the femoral head is controversial. In these situations, the outcome of joint preservation procedures is poor. There are several arthroplasty options for late-stage disease. The clinical outcomes of hemiarthroplasty and hemiresurfacing are unpredictable because of progressive acetabular cartilage degeneration. Total hip resurfacing may be associated with further vascular insult to the femoral head and early failure of the implant. Total hip replacement with metal-on-conventional polyethylene bearing surfaces has been the gold standard, but implant survivorship is limited in young active patients due to wear and osteolysis. Newer alternative bearing surfaces may have improved wear characteristics, but their durability must be confirmed in longer-term studies.

Prevalence of Failure due to Adverse Reaction to Metal Debris in Modern, Medium and Large Diameter Metal-on-Metal Hip Replacements--The Effect of Novel Screening Methods: Systematic Review and Metaregression Analysis

Metal-on-metal (MoM) hip replacements were used for almost a decade before adverse reactions to metal debris (ARMD) were found to be a true clinical problem. Currently, there is a paucity of evidence regarding the usefulness of systematic screening for ARMD. We implemented a systematic review and meta-analysis to establish the prevalence of revision confirmed ARMD stratified by the use of different screening protocols in patients with MoM hip replacements. Five levels of screening were identified: no screening (level 0), targeted blood metal ion measurement and/or cross-sectional imaging (level 1), metal ion measurement without imaging (level 2), metal ion measurement with targeted imaging (level 3) and comprehensive screening (both metal ions and imaging for all; level 4). 122 studies meeting our eligibility criteria were included in analysis. These studies included 144 study arms: 100 study arms with hip resurfacings, 33 study arms with large-diameter MoM total hip replacements (THR), and 11 study arms with medium-diameter MoM THRs. For hip resurfacing, the lowest prevalence of ARMD was seen with level 0 screening (pooled prevalence 0.13%) and the highest with level 4 screening (pooled prevalace 9.49%). Pooled prevalence of ARMD with level 0 screening was 0.29% and with level 4 screening 21.3% in the large-diameter MoM THR group. In metaregression analysis of hip resurfacings, level 4 screening was superior with regard to prevalence of ARMD when compared with other levels. In the large diameter THR group level 4 screening was superior to screening 0,2 and 3. These outcomes were irrespective of follow-up time or study publication year. With hip resurfacings, routine cross-sectional imaging regardless of clinical findings is advisable. It is clear, however, that targeted metal ion measurement and/or imaging is not sufficient in the screening for ARMD in any implant concepts. However, economic aspects should be weighed when choosing the preferred screening level.

Hip resurfacing versus total hip arthroplasty: a systematic review comparing standardized outcomes

BACKGROUND

Metal-on-metal hip resurfacing was developed for younger, active patients as an alternative to THA, but it remains controversial. Study heterogeneity, inconsistent outcome definitions, and unstandardized outcome measures challenge our ability to compare arthroplasty outcomes studies.

QUESTIONS/PURPOSES

We asked how early revisions or reoperations (within 5 years of surgery) and overall revisions, adverse events, and postoperative component malalignment compare among studies of metal-on-metal hip resurfacing with THA among patients with hip osteoarthritis. Secondarily, we compared the revision frequency identified in the systematic review with revisions reported in four major joint replacement registries.

METHODS

We conducted a systematic review of English language studies published after 1996. Adverse events of interest included rates of early failure, time to revision, revision, reoperation, dislocation, infection/sepsis, femoral neck fracture, mortality, and postoperative component alignment. Revision rates were compared with those from four national joint replacement registries. Results were reported as adverse event rates per 1000 person-years stratified by device market status (in use and discontinued). Comparisons between event rates of metal-on-metal hip resurfacing and THA are made using a quasilikelihood generalized linear model. We identified 7421 abstracts, screened and reviewed 384 full-text articles, and included 236. The most common study designs were prospective cohort studies (46.6%; n = 110) and retrospective studies (36%; n = 85). Few randomized controlled trials were included (7.2%; n = 17).

RESULTS

The average time to revision was 3.0 years for metal-on-metal hip resurfacing (95% CI, 2.95-3.1) versus 7.8 for THA (95% CI, 7.2-8.3). For all devices, revisions and reoperations were more frequent with metal-on-metal hip resurfacing than THA based on point estimates and CIs: 10.7 (95% CI, 10.1-11.3) versus 7.1 (95% CI, 6.7-7.6; p = 0.068), and 7.9 (95% CI, 5.4-11.3) versus 1.8 (95% CI, 1.3-2.2; p = 0.084) per 1000 person-years, respectively. This difference was consistent with three of four national joint replacement registries, but overall national joint replacement registries revision rates were lower than those reported in the literature. Dislocations were more frequent with THA than metal-on-metal hip resurfacing: 4.4 (95% CI, 4.2-4.6) versus 0.9 (95% CI, 0.6-1.2; p = 0.008) per 1000 person-years, respectively. Adverse event rates change when discontinued devices were included.

CONCLUSIONS

Revisions and reoperations are more frequent and occur earlier with metal-on-metal hip resurfacing, except when discontinued devices are removed from the analyses. Results from the literature may be misleading without consistent definitions, standardized outcome metrics, and accounting for device market status. This is important when clinicians are assessing and communicating patient risk and when selecting which device is most appropriate for individual patients.

Osteonecrosis of the hip: treatment options and outcomes

This article reviews the literature regarding the outcomes of various nonoperative and operative treatment options for osteonecrosis of the hip. This article provides the orthopedic community with the latest evidence regarding the suitability of currently available treatment modalities in various stages of the disease.

Preliminary results of implantation in animal model and osteoblast culture evaluation of prototypes of biomimetic multispiked connecting scaffold for noncemented stemless resurfacing hip arthroplasty endoprostheses

We present the new fixation method for RHA (resurfacing hip arthroplasty) endoprostheses by means of the biomimetic multispiked connecting scaffold (MSC-Scaffold). Such connecting scaffold can generate new type of RHA endoprostheses, that is stemless and fixed entirely without cement. The preprototypes of this MSC-Scaffold were manufactured with modern additive laser additive technology (SLM). The pilot surgical implantations in animal model (two laboratory swine) of MSC-Scaffold preprototypes have showed after two months neither implant loosening, migration, and nor other early complications. From the results of performed histopathological evaluation of the periscaffold spikes bone tissue and 10-day culture of human osteoblasts (NHOst) we can conclude that (1) the scaffolding effect was obtained and (2) to improve the osseointegration of the scaffold spikes, their material surface should be physicochemically modified (e.g., with hydroxyapatite). Some histopathological findings in the periscaffold domain near the MSC-Scaffold spikes bases (fibrous connective tissue and metallic particles near the MSC-Scaffold spikes bases edges) prompt considering the necessity to optimize the design of the MSC-Scaffold in the regions of its interspike space near the spikes bases edges, to provide more room for new bone formation in this region and for indispensable post-processing (glass pearl blasting) after the SLM manufacturing.

Vascularized fibular grafts in patients with avascular necrosis of femoral head: a systematic review and meta-analysis

BACKGROUND

Vascularized fibular grafting (VFG) has been initiated to treat avascular necrosis of the femoral head (ANFH) since the late 1970s. There are a number of review articles updating the use of VFG to treat the ANFH. None of them applied statistical analysis for combining results from different studies to obtain a quantitative estimate of the overall effect and potential harm of VFG in comparison to other treatment.

METHODS

Several electronic databases were searched to find studies using VFG to treat ANFH. The outcomes sought included Harris Score, failure rate (conversion to total hip arthroplasty (THA) and/or femoral head collapse), and complications rate. Included studies were assessed for methodological bias and estimates of effect were calculated. Potential reasons for heterogeneity were explored.

RESULTS

The clinical results of 69.0 % of VFG-treated patients and 25.0 % of non-VFG-treated patients were good to excellent (OR 0.13; p < 0.01). The conversion rate to THA of VFG-treated and that of other methods treated hips was 16.5 % and 42.6 % (OR 0.19; p < 0.001). Collapse rate of VFG-treated and that of non-VFG-treated hips was 16.7 % and 63.6 % (OR 0.09; p < 0.05). The complication rate of VFG-treated and that of other methods treated patients was 23.8 % and 8.9 % (OR 3.44; p = 0.09). For Steinberg stage I, II ANFH, failure rate of VFG-treated and that of non-VFG-treated hips was 9.8 % and 40.2 % (OR 0.17; p < 0.001). For Steinberg stage II, III ANFH, failure rate of VFG-treated and that of non-VFG-treated hips was 16.5 % and 42.8 %, respectively (OR 0.17; p < 0.001).

CONCLUSIONS

VFG is a justified method that can prevent the ANFH from progressing to collapse, and that can retard or avoid hip replacement, especially in the hips of Steinberg stage I, II, and III.

Treatment of femoral head osteonecrosis with advanced cell therapy in sheep

BACKGROUND

The purpose of this study was to evaluate the efficacy of core decompression associated with advanced cell therapy for the treatment of femoral head osteonecrosis in an established sheep model.

METHODS

Early stage osteonecrosis of the right hip was induced cryogenically in 15 mature sheep. At 6 weeks, the sheep were divided into three groups, Group A: core decompression only; Group B: core decompression followed by implantation of an acellular bone matrix scaffold; Group C: core decompression followed by implantation of a cultured BMSC loaded bone matrix scaffold. At 12 weeks, MRI hip studies were performed and then the proximal femur was harvested for histological analysis.

RESULTS

In the group of advanced cell therapy, Group C, there was a tendency to higher values of the relative surface of newly formed bone with a mean of 20.3 versus 11.27 % in Group A and 13.04 % in Group B but it was not statistically significant. However, the mean relative volume of immature osteoid was 8.6 % in Group A, 14.97 in Group B, and 53.49 % in Group C (p < 0.05), revealing a greater capacity of osteoid production in the sheep treated with BMSCs. MRI findings were not conclusive due to constant bone edema artifact in all cases.

CONCLUSIONS

Our findings indicate that a BMCSs loaded bone matrix scaffold is capable of stimulating bone regeneration more effectively than isolated core decompression or in association with an acellular scaffold in a preclinical femoral head osteonecrosis model in sheep.

Hip resurfacing: a systematic review of literature

PURPOSE

We conducted a systematic review of the literature in order to take stock of hip resurfacing according to the principle of "evidence based medicine". Our main objective was to compare the rate of revision of resurfacing implants with survival limits set by the National Institute of Clinical Excellence (NICE).

METHODS

A systematic review was undertaken of all published (Medline, Cochrane, EMBASE) literature research databases up to July 2012 as recommended by the PRISMA statement. Data extraction focused on functional outcomes, complications and survival rates. The survival rates of implants were analysed according to the mean of the series in comparison to the NICE criteria.

RESULTS

Fifty-three studies were identified and included 26,456 cases with an average of 499.17 ± 856.7 (range, 38-5000) cases per study. The median survival was 95.57 % ± 3.7 % (range, 84-100). The percentage of studies which satisfied the criteria set by NICE was 69.8 %. In terms of cumulative revision rates pondered by the number of implants, BHR®, Conserve Plus® and Cormet® showed the best results. The mean postoperative score was 91.2 ± 7.72 (range, 68.3-98.6). There was no statistically significant difference between implants in terms of functional outcomes.

CONCLUSION

On the basis of the current evidence base, this review of the literature emphasises the importance of certain parameters that can improve the results of resurfacing. The type of implant seems to play an important role as does patient selection.

Metal-on-Metal Bearing: Is This the End of the Line? We Do Not Think So

BACKGROUND

Recent studies have recommended the discontinuation of metal-on-metal (MoM) components in total hip arthroplasty (THA) because of adverse effects reported with large-diameter MoM THA. This is despite favorable long-term results observed with 28 and 32 mm MoM bearings.

QUESTIONS/PURPOSES

The aim of this study was to assess the value of calls for an end to MoM bearings as THA components. Specifically, we wish to address the risks associated with MoM bearings including adverse soft tissue reactions, metal ion release, and carcinogenic risk.

METHODS

The study evaluates the arguments in the literature reporting on MoM (adverse soft tissue reactions, metal ion release, and carcinogenic risk) and the experience of the current authors who re-introduced these bearings in 1995. They are balanced by a benefit-risk review of the literature and the authors' experience with MoM use.

RESULTS

Adverse reactions to metallic debris as well as metal ion release are predictable and can be prevented by adequate design (arc of coverage, clearance), metallurgy (forged instead of cast alloy, high-carbide content), and appropriate component orientation. There is no scientific evidence that carcinogenicity is increased in subjects with MoM hip prostheses. MoM articulations appear to be attractive allowing safe hip resurfacing, decreasing the risk of THA revision in active patients, and providing secure THA fixation with cement in cages in severely deformed hips. MoM bearings in women of child-bearing age are controversial, but long-term data on metallic devices in adolescents undergoing spinal surgery seem reassuring.

DISCUSSION

Adequate selection of MoM articulations ensures their safe use. These articulations are sensitive to orientation. Fifteen years of safe experience with 28- and 32-mm bearings of forged alloy and high-carbide content is the main reason for retaining them in primary and revision THA.

Revision rate of Birmingham Hip Resurfacing arthroplasty: comparison of published literature and arthroplasty register data

PURPOSE

Hip resurfacing arthroplasty has gained popularity for treating young and active patients who have arthritis. There are two major data sources for assessing outcome and revision rate after total joint arthroplasty: sample-based clinical trials and national arthroplasty registers. The purpose of this study was to evaluate the outcome of the Birmingham Hip Resurfacing (BHR) arthroplasty in terms of revision rate as reported in clinical studies and recorded by national arthroplasty registers.

METHODS

A comprehensive literature research was performed from English-language, peer-reviewed journals and annual reports from national joint arthroplasty registers worldwide. Only publications from MEDLINE-listed journals were included. The revision rate was used as the primary outcome parameter. In order to allow for direct comparison of different data sets, calculation was based on revisions per 100 observed component years. For statistical analysis, confidence intervals (CI) were calculated.

RESULTS

A total of 18,708 implants, equivalent to 106,565 observed component years, were analysed in the follow-up studies. The register reports contained 9,806 primary cases corresponding to 44,294 observed component years. Statistical analysis revealed a significant difference in revisions per 100 observed component years between the development team (0.27; CI: 0.14-0.40) and register data (0.74; CI: 0.72-0.76).

CONCLUSION

The BHR arthroplasty device shows good results in terms of revision rate in register data as well as in clinical studies. However, the excellent results reported by the development team are not reproducible by other surgeons. Based on the results of our study, we believe that comprehensive national arthroplasty registers are the most suitable tool for assessing hip arthroplasty revision rate.

Review of total hip resurfacing and total hip arthroplasty in young patients who had Legg-Calvé-Perthes disease

Patients with Legg-Calvé-Perthes disease can often be successfully treated with femoral head-preserving measures, such as bracing, or containment procedures with osteotomies. However, in some cases, after resolution of the disease, the femoral head may proceed to collapse or progress to severe arthritis at a young age. If nonoperative methods have failed, the only treatment options available for these adolescents or young adults may be a total hip resurfacing or a total hip arthroplasty (THA). This article focuses on the results and unique technical considerations of resurfacing and THA for patients who have severe hip osteoarthritis after resolved Legg-Calvé-Perthes disease.

Hip resurfacing in patients who have osteonecrosis and are 25 years or under

BACKGROUND

Young patients with osteonecrosis (ON) treated with THA often have suboptimal function and radiographic failure with eventual revision. Resurfacing may be an option because of potentially increased functionality and decreased radiographic failure, although neither has been confirmed in the literature.

QUESTIONS/PURPOSES

We therefore compared the clinical scores and radiographic failures of resurfacing patients 25 years or younger with osteonecrosis with those for patients with ON treated with THA.

METHODS

We identified 17 patients (20 resurfaced hips) who were 25 years or younger and treated by resurfacing for ON. Mean followup was 62 months (range, 32-103 months). This group was matched by gender, age, BMI, and followup to 16 patients (20 hips) treated with THA with a mean 61 month followup (range, 34-88 months). Additionally, the group was compared to 78 patients (87 hips) with ON over age 25 who underwent resurfacing during the same time with a mean followup of 61 months (range, 27-112 months).

RESULTS

The mean Harris score improved from 48 points preoperatively to 93 points with a 100% 7.5 year survivorship in the young resurfacing group. In the THA cohort, the mean score improved from 44 points preoperatively to 94 points postoperatively, with a 93.3% 7.5 year survivorship; similar to the results for all resurfacing patients. Radiographs did not reveal malalignment or progressive radiolucencies in any cohort.

CONCLUSION

At approximately 5 year followup, young resurfacing patients were similar to other resurfacing patients and standard THA patients regarding clinical ratings and radiographic failures.

Survival of metal-on-metal hip resurfacing arthroplasty: a systematic review of the literature

We systematically reviewed the peer-reviewed literature to relate the survival of hybrid metal-on-metal hip resurfacing arthroplasty devices to a National Institute of Clinical Excellence (NICE) benchmark for choosing a primary total hip replacement, which is a survival rate of 90% at a follow-up of ten years. A total of 29 articles (10 621 resurfaced hips) met the inclusion criteria. The mean follow-up ranged from 0.6 to 10.5 years and the survival of the implant ranged from 84% to 100%. Of the 10 621 hips, 370 were revised (3.5%), with aseptic loosening as the most frequent mode of failure. None of the hip resurfacing arthroplasty implants used to date met the full ten-year NICE benchmark of survival. A total of 13 studies showed satisfactory survival compared with the three-year NICE benchmark.