Independent predictors of revision following metal-on-metal hip resurfacing

Revision of metal-on-metal hip replacements with dual-mobility bearings and acetabular component retention

Aims

In metal-on-metal (MoM) hip arthroplasties and resurfacings, mechanically induced corrosion can lead to elevated serum metal ions, a local inflammatory response, and formation of pseudotumours, ultimately requiring revision. The size and diametral clearance of anatomical (ADM) and modular (MDM) dual-mobility polyethylene bearings match those of Birmingham hip MoM components. If the acetabular component is satisfactorily positioned, well integrated into the bone, and has no surface damage, this presents the opportunity for revision with exchange of the metal head for ADM/MDM polyethylene bearings without removal of the acetabular component.

Methods

Between 2012 and 2020, across two centres, 94 patients underwent revision of Birmingham MoM hip arthroplasties or resurfacings. Mean age was 65.5 years (33 to 87). In 53 patients (56.4%), the acetabular component was retained and dual-mobility bearings were used (DM); in 41 (43.6%) the acetabulum was revised (AR). Patients underwent follow-up of minimum two-years (mean 4.6 (2.1 to 8.5) years).

Results

In the DM group, two (3.8%) patients underwent further surgery: one (1.9%) for dislocation and one (1.9%) for infection. In the AR group, four (9.8%) underwent further procedures: two (4.9%) for loosening of the acetabular component and two (4.9%) following dislocations. There were no other dislocations in either group. In the DM group, operating time (68.4 vs 101.5 mins, p < 0.001), postoperative drop in haemoglobin (16.6 vs 27.8 g/L, p < 0.001), and length of stay (1.8 vs 2.4 days, p < 0.001) were significantly lower. There was a significant reduction in serum metal ions postoperatively in both groups (p < 0.001), although there was no difference between groups for this reduction (p = 0.674 (cobalt); p = 0.186 (chromium)).

Conclusion

In selected patients with Birmingham MoM hips, where the acetabular component is well-fixed and in a satisfactory position with no surface damage, the metal head can be exchanged for polyethylene ADM/MDM bearings with retention of the acetabular prosthesis. This presents significant benefits, with a shorter procedure and a lower risk of complications.

Conversion Birmingham Hip Resurfacing in Managing Post-traumatic Arthritis With Retained Femoral Hardware: A Case Report

CASE

A 70-year-old man with a year-long history of arthritic pain in his left hip presented to our clinic. He had a left intertrochanteric hip fracture 6 years ago, fixed with an open reduction internal fixation with a cephalomedullary nail. He underwent a conversion Birmingham Hip Resurfacing (BHR) with removal of the proximal helicoidal blade and retention of the intramedullary nail. At 7-year follow-up, the patient reported satisfactory clinical outcomes and excellent radiographic fixation.

CONCLUSION

This case highlights using conversion BHR in patients with post-traumatic arthritis with retained femoral hardware as an alternative to conventional total hip arthroplasty.

Are serum cobalt and chromium levels predictors for patient-reported outcome measures in the ASR hip resurfacing arthroplasty?

Aims

The aims of this study were to determine if an increasing serum cobalt (Co) and/or chromium (Cr) concentration is correlated with a decreasing Harris Hip Score (HHS) and Hip disability and Osteoarthritis Outcome Score (HOOS) in patients who received the Articular Surface Replacement (ASR) hip resurfacing arthroplasty (HRA), and to evaluate the ten-year revision rate and show if sex, inclination angle, and Co level influenced the revision rate.

Methods

A total of 62 patients with an ASR-HRA were included and monitored yearly postoperatively. At follow-up, serum Co and Cr levels were measured and the HHS and the HOOS were scored. In addition, preoperative patient and implant variables and the need for revision surgery were recorded. We used a linear mixed model to relate the serum Co and Cr levels to different patient-reported outcome measures (PROMs). For the survival analyses we used the Kaplan-Meier and Cox regression model.

Results

We found that an increase of one part per billion (ppb) in serum Co and Cr levels correlated significantly with worsening of the HHS in the following year. This significant correlation was also true for the HOOS-Pain and HOOS-quality of life sub scores. The overall ten-year survival rate in our cohort was 65% (95% confidence interval (CI) 52.5 to 77.6). Cox regression analysis showed a significant hazard ratio (HR) of 1.08 (95% CI 1.01 to 1.15; p = 0.028) for serum Co level. No significance was found with sex or inclination angle.

Conclusion

This study shows that increasing serum Co and Cr levels measured in patients with an ASR-HRA are predictive for deterioration in HHS and HOOS subscales in the following year. Increasing serum Co and Cr should forewarn both surgeon and patient that there is a heightened risk of failure. Continued and regular review of patients with an ASR-HRA implant by measurement of serum Co/Cr levels and PROMs remains essential.

Midterm results of the Birmingham hip resurfacing: a single-surgeon series

INTRODUCTION

Birmingham hip resurfacing (BHR) is readily used as alternative to total hip replacement in younger patients. The current study aims to compare outcomes in terms of adverse local tissue reactions (ALTR), elevated metal ion levels and survival rates between low-risk (femoral component size ≥ 48 mm) and high-risk (femoral component size < 48 mm) BHR patients at a minimum 5-year follow-up (FU).

MATERIALS AND METHODS

We report the minimum 5-year, single surgeon outcome results of 183 BHRs, performed between 2007 and 2012. 154 patients, 18 women (20 hips) and 136 men (163 hips) were included in the study. Patients were grouped in 149 low-risk cases (femoral component size ≥ 48 mm) and in 34 high-risk cases (18 female/12 male) patients with a femoral head size < 48 mm).

RESULTS

At a minimum of 5-years FU time, 91% of the patients were available for FU. The overall survival rate was 91.8%. There were five revisions (survival rate 96.6%) in the low-risk group and ten revisions (survival rate 70.6%) in the high-risk group. In the low-risk group, six patients (6.5%) showed elevated metal ion levels (> 7 μg/l), compared to five patients (20.8%) in the high risk-group (p = 0.03).

CONCLUSION

Including the surgeon's initial learning curve, the BHR shows very good mid-term survival rates in the low-risk group but should, as previously demonstrated, not be considered for patients with less than 48 mm femoral head size.

LEVEL OF EVIDENCE

Level III: retrospective cohort study.

Metal-on-Metal Hips: Ten-Year Clinical and Radiographic Outcomes of the ADEPT Metal-on-Metal Hip Resurfacing and Modular Total Hip Arthroplasty

BACKGROUND

The aim of this study is to update the 10-year follow-up survivorship and metal ions levels of a cohort of metal-on-metal (MoM) hip resurfacing (HR) and large-diameter-head (LDH) total hip arthroplasty (THA).

METHODS

The study is a retrospective analysis of prospectively collected data that compared the outcomes of 24 MoM HR (21 patients) and 15 (11 patients) modular LHD MoM THA at >10 years follow-up. Baseline characteristics as well as intraoperative and postoperative information were collected, including complications, revisions, clinical and radiographic outcomes, and serum metal ions level (Cobalt, Chromium). Metal ion levels were compared using a two-tailed unpaired t-test and Wilcoxon signed-rank test (jamovi v2.3.3.0, Sydney, NSW, AU).

RESULTS

No significant differences were detected in gender, BMI, and ASA score between the two groups. Patients in the modular THA group were significantly older (57 years vs. 46 years; p < 0.05). The HR overall survivorship was 91.7% (22 of 24 hips) with survivorship from implant failure and/or aseptic loosening and/or metal debris related 100% of problems. The modular THA overall survivorship was 86.7% (13 of 15 hips) with survivorship from implant aseptic loosening and metal ions complications of 93.4% (14 of 15 hips). No significant difference was noted when comparing clinical outcomes. Metal ions were significantly lower in the HR group (Co 25.8 nmol/L vs. 89 nmol/L; p < 0.001-Cr 33.5 nmol/L vs. 55.2 nmol/L; p = 0.026).

CONCLUSION

Both implants reported excellent and comparable clinical outcomes at >10 years follow-up. The Adept HR reported remarkable survivorship, in line with the registry data, proving once again its reliability in young active males. The modular LDH THA, despite being discontinued, presented higher reliability and a lower failure rate when compared with similar withdrawn MoM implants. Trunnionosis did not appear to be a significant problem in this particular modular design.

Hip resurfacing and posterior approach total hip arthroplasty have equivalent blood loss when tranexamic acid is used: a propensity score matched cohort analysis

INTRODUCTION

Hip resurfacing (HR) requires a larger approach and soft tissue dissection and might therefore be associated with increased blood loss compared to total hip arthroplasty (THA). However, the effect of the adoption of tranexamic acid (TXA) in this setting is unknown. Therefore, the current study compares the blood loss and transfusion requirements between HR and posterior THA in patients receiving TXA.

MATERIALS AND METHODS

This retrospective cohort study included patients undergoing primary, unilateral THA or HR using a posterior approach between February 2016 and 2020 in which TXA was administered. THA and HR patients were propensity score matched using nearest neighbor greedy matching accounting for demographic, health and surgical variables. Postoperative hemoglobin (Hgb) levels and Hgb drop from preoperative to post-operative day (POD) 1 were compared using t-tests and associated risk factors were assessed using linear mixed modelling.

RESULTS

After matching, each cohort consisted of 1395 patients. Cohorts were similar regarding age, sex, BMI, and Charlson Comorbidity Index. No significant differences were found for Hgb levels on POD 1 (12.3 g/dl; p = 0.90) or Hgb drop (2.3 g/dl; p = 0.87). Duration of surgery was significantly longer for HR patients (82 vs 77 min; p < 0.01). Transfusion rate was 0.1% in both cohorts (p = 1.00). Hospital stay was significantly shorter for HR patients (1 vs 2 days; p < 0.01).

CONCLUSION

HR using a standard TXA regimen is not associated with greater perioperative blood loss than posterior THA and does not result in increased transfusion requirements. Both surgical procedures can be considered equally safe in terms of perioperative blood management when TXA is used.

Survival rates of different bearing surfaces with the same model of stem in total hip arthroplasty: predictive factors for revision surgery

INTRODUCTION

Few studies have examined the survival rates of total hip arthroplasty (THA) with the same femoral stem, and the predictive factors leading to the revision of stemmed metal-on-metal (MoM) THA remain unknown. We determined the long-term survival rate of stemmed MoM THA compared with that of metal-on-polyethylene (MoP) bearing THA, the effect of head size and cup placement angle on revision rate, and predictors of revision.

MATERIALS AND METHODS

A total of 130 hips in 110 patients who underwent primary THA by the same surgeon were included. M2a-RingLoc with a metal-on-polyethylene bearing (group P, 53 hips), M2a-Taper with MoM bearing (group T, 44 hips), and M2a-Magnum with MoM bearing (group M, 33 hips) were used. The mean age at surgery was 63.1 ± 9.5 years, and the mean postoperative follow-up duration was 133.7 ± 39.1 months. Whole blood metal ion concentrations were measured preoperatively and postoperatively, and magnetic resonance imaging was performed to identify aseptic local tissue reactions (ALTRs). Kaplan-Meier survivorship analysis and multiple logistic regression analysis were performed.

RESULTS

The THA survival rate up to the maximum postoperative follow-up period was 96.2% at 173 months, 46.6% at 179 months, and 47.8% at 145 months in groups P, T, and M, respectively, with revision as the endpoint. The stemmed MoM THA recorded a very low survival rate (p < 0.001). The ALTR rates were 70.5% and 63.6% in groups T and M, respectively. The risk factor for revision was the use of MoM bearing, and there was no difference in the results based on the head size in group M. Cobalt levels continued to increase postoperatively, although they were not accurate predictors of revision.

CONCLUSIONS

Stemmed MoM THA has a very low survival rate and should be used with caution. It is important to monitor the patient's symptoms and perform appropriate imaging to ensure timely revision.

What is the Level of Evidence Substantiating Commercial Payers' Coverage Policies for Total Joint Arthroplasty?

BACKGROUND

The prevalence of total joint arthroplasty (TJA) in the United States has drawn the attention of health care stakeholders. The payers have also used a variety of strategies to regulate the medical necessity of these procedures. The purpose of this study was to examine the level of evidence of the coverage policies being used by commercial payers in the United States.

METHODS

The references of the coverage policies of four commercial insurance companies were reviewed for type of document, level of evidence, applicability to a TJA population, and success of nonoperative treatment in patients with severe degenerative joint disease.

RESULTS

282 documents were reviewed. 45.8% were primary journal articles, 14.2% were level I or II, 41.2% were applicable to patients who were candidates for TJA, and 9.9% discussed the success of nonoperative treatment in patients who would be candidates for TJA.

CONCLUSION

Most of the references cited by commercial payers are of a lower level of scientific evidence and not applicable to patients considered to be candidates for TJA. This is relatively uniform across the reviewed payers. The dearth of high-quality literature cited by commercial payers reflects the lack of evidence and difficulty in conducting high level studies on the outcomes of nonoperative versus operative treatment for patients with severe, symptomatic osteoarthritis. Patients, surgeons, and payers would all benefit from such studies and we encourage professional societies to strive toward that end through multicenter collaboration.

Uncemented versus cemented arthroplasty after metal-on-metal total hip replacement in patients with femoral neck fractures: a retrospective study

OBJECTIVE

To compare the clinical outcomes of primary metal-on-metal total hip replacement (MoM-TR) converted to uncemented total hip replacement (UTR) or cemented total hip replacement (CTR) in patients with femoral neck fractures (AO/OTA: 31B/C).

METHODS

Patient data of 234 UTR or CTR revisions after primary MoM-TR failure from March 2007 to January 2018 were retrospectively identified. Clinical outcomes, including the Harris hip score (HHS) and key orthopaedic complications, were collected at 3, 6, and 12 months following conversion and every 12 months thereafter.

RESULTS

The mean follow-up was 84.12 (67-100) months for UTR and 84.23 (66-101) months for CTR. At the last follow-up, the HHS was better in the CTR- than UTR-treated patients. Noteworthy dissimilarities were correspondingly detected in the key orthopaedic complication rates (16.1% for CTR vs. 47.4% for UTR). Statistically significant differences in specific orthopaedic complications were also detected in the re-revision rate (10.3% for UTR vs. 2.5% for CTR), prosthesis loosening rate (16.3% for UTR vs. 5.9% for CTR), and periprosthetic fracture rate (12.0% for UTR vs. 4.2% for CTR).

CONCLUSION

In the setting of revision of failed primary MoM-TR, CTR may demonstrate advantages over UTR in improving functional outcomes and reducing key orthopaedic complications.

The establishment of the Korean medical device safety information monitoring center: Reviewing ten years of experience

Medical devices may revolutionize healthcare delivery but can lead to serious adverse events for treated patients and users. While reporting of adverse events related to medical devices is an essential starting point for post-market surveillance, underreporting of medical device adverse events is a global problem. Korea introduced a voluntary medical device adverse event reporting system in 2010, called the Medical Device Safety Information Monitoring Center, which has led to an increase in adverse event reports. For 10 years, the Medical Device Safety Information Monitoring Center has analyzed medical device adverse events systematically and has provided active feedback to the manufacturers and education on safe use. Recently, the Medical Device Safety Information Monitoring Center contributed to harmonization of international medical device vigilance through the sharing of adverse events. This experience of Korea might contribute to improvements in medical device vigilance, which is a critical prerequisite for improving medical device policies and regulations.

Despite higher revision rate, MoM large-head THA offers better clinical scores than HR: 14-year results from a randomized controlled trial involving 48 patients

BACKGROUND

The high failure rates of metal on metal (MoM) large diameter head total hip arthroplasty (LDH THA) and hip resurfacing (HR) prevented their long-term comparisons with regards to clinical outcome. Such knowledge would be important as ceramic LDH bearing is now available. With long-term follow-up, we investigated the difference in 1) patient-reported outcome measures (PROMs); 2) revision and adverse events rates, and 3) metal ion levels between MoM LDH THA and HR.

METHODS

Forty-eight patients were randomized for LDH THA (24) or HR (24) with the same MoM articulation. At a mean follow-up of 14 years, we compared between groups different PROMs, the number of revisions and adverse events, whole blood Cobalt (Co) and Chromium (Cr) ion levels, and radiographic signs of implant dysfunction.

RESULTS

LDH THA (all cases: revised and well-functioning) had significantly better WOMAC (94 versus 85, p = 0.04), and more frequently reported having no limitation (p = 0.04). LDH THA revision rate was 20.8% (5/24) versus 8.3% (2/24) for HR (p = 0.4). Mean Co and Cr ion levels were higher in LDH THA compared to the HR (Co: 3.8 μg/L vs 1.7 μg/L; p = 0.04 and Cr: 1.9 μg/L vs 1.4 μg/L, p = 0.1). On radiographic analyses, 2 LDH THAs showed signs of adverse reaction to metal debris, whereas 1 loose femoral HR component was documented.

CONCLUSION

In the long-term, MoM LDH THA had a high trunnion related revision rate but nonetheless showed better PROMs compared to HR. Provided with a well-functioning modular junction, non-MoM LDH THA would offer an appealing option.

TRIAL REGISTRATION

ClinicalTrials.gov ( NCT04516239 ), August 18, 2020. Retrospectively registered.

A Comparative Cohort Study With a 20-Year Age Gap: Hip Resurfacing in Patients Aged ≤35 Years and Patients Aged ≥55 Years

Background

This single-center retrospective cohort study aimed to evaluate and compare implant survival and patient-reported outcome measures in 2 distinct age groups separated by 20 years who underwent hip resurfacing arthroplasty (HRA).

Methods

Between 2005 and 2014, 2042 HRAs were performed by a single-surgeon, and 75 and 377 hips from patients aged ≤35 years and ≥55 years, respectively, were included in this study. Implant survival was determined for all available hips. Clinical features and patient-reported outcome measures were collected.

Results

Seven hips were revised, 4 for aseptic loosening of one or both components, one for infection, one for accelerated wear and metallosis, and one for femoral neck fracture. There was no difference in all-cause 10-year revision, with 97.1% (95% confidence interval 80.9 to 99.6) and 99.6% (95% confidence interval: 97 to 99.9) survivorship in younger and older patients, respectively (P = .246). Preoperatively, younger patients were less active than older patients on the Lower Extremity Activity Scale (LEAS) or University of California, Los Angeles, activity scale, but at follow-up, younger patients outpaced older ones.

Conclusion

Original to our study was the isolation and comparison of 2 distinct age groups. With excellent results in disparate age groups, HRA can be applied to a broad patient demographic and is suitable for those patients who want to achieve a high activity level as defined by Lower Extremity Activity Scale or University of California, Los Angeles, scores.

Hip Resurfacing Compared with 28-mm Metal-on-Metal Total Hip Replacement: A Randomized Study with 15 Years of Follow-up

BACKGROUND

Bone stock conservation, hip anatomy preservation, and greater stability are among the promoted advantages of hip resurfacing (HR). However, the disappointing failure of some implants nearly led to its abandonment. The aim of this study was to compare clinical scores and revision and complication rates after HR with those after total hip arthroplasty (THA).

METHODS

Two hundred and three hips were randomized to 28-mm metal-on-metal (MoM) THA (99 hips) or to HR (104 hips). Main outcome measures compared between groups were the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, the revision rate, and the complication rates. The radiographic findings were also assessed.

RESULTS

After a mean follow-up of 15 years (range, 14 to 16 years), 9 (4.4%) of the 203 patients were lost to follow-up and 15 (7.4%) had died. The Kaplan-Meier survivorship, with revision for any reason as the end point, was 89.2% (95% confidence interval [CI], 82.3% to 96.1%) for HR and 94.2% (95% CI, 89.3% to 99.1%) for THA (p = 0.292). The reasons for revision included infection (3 patients), recurrent dislocation (1 patient), and adverse reaction to metal debris (ARMD) (1 patient) in the THA group and ARMD (2 patients) and femoral head loosening (7 patients) in the HR group. With aseptic revision as the end point, the Kaplan-Meier survivorship was significantly higher in the THA group (97.4% versus 89.2%; p = 0.033). No dislocation occurred in the HR group compared with 4 in the THA group (p = 0.058). Both groups achieved a similar mean WOMAC score (10.7 in the HR group and 8.8 in the THA group; p = 0.749), Forgotten Joint Score (87.1 and 85.3, respectively; p = 0.410), University of California Los Angeles (UCLA) activity score (6.3 and 6.4, respectively; p = 0.189), and overall joint perception (p = 0.251).

CONCLUSIONS

The specific HR and MoM 28-mm THA implants used in this study showed good long-term survival and function. The overall rates of complications and revisions were similar in both groups but were of different types. As it provides better femoral bone preservation and biomechanical reconstruction, HR may continue to have a role in selected patients when performed by experienced surgeons and using validated implants.

LEVEL OF EVIDENCE

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

Revision of a Monoblock Metal-on-Metal Cup Using a Dual Mobility Component: Is It a Reasonable Option?

Revision of large-diameter, monoblock acetabular components for both hip resurfacing arthroplasty and metal-on-metal (MoM) total hip arthroplasty (THA) is correlated to a high amount of complications. For this reason, performing a limited revision by conversion to a dual mobility (DM) without acetabular component exchange has been proposed in order to limit these complications. Although DM bearing offers an easy solution avoiding the intraoperative and time-associated complications, concern about polyethylene wear and stability remains due to the difference regarding the design, the coverage angle and the clearance of the two implants. In order to evaluate the performance of this new solution with the new material to prevent the possibility of failure it is essential to conduct a review of the literature A qualitative systematic review of the literature has been conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search of PubMed, EMBASE, Google Scholar, and Scopus for English and French articles between January 2000 and October 2019 was performed, with the primary objective of finding articles about dual mobility bearing coupling with large metal-on-metal cup in the case of hip revision procedure. Various combinations of the key words were used in the search strategy. Thirteen articles with DM bearing mated with MoM cup were analyzed. Of the 130 hip revisions selected, with a follow-up from 6 to 53 months, there were a total of 14 with complications (10.77%): four true dislocations (3.08%); six intra-prosthetic dislocations (IPD, 4.6%), two of which presented plastic deformation and polyethylene wear; four other complications (3.08%), included a cup osteolysis, a clicking noise, a superficial infection and a periprosthetic fracture. All the mentioned true dislocations occurred during the first month while IPDs appeared during the first two years from the index revision. In conclusion, according to the literature analyzed, we can stress that the concerns and doubts about mating a DM bearing with large MoM cup cannot be dissolved. It has been pointed out that a DM bearing is not designed for a MoM cup; it is not mechanically tested on MoM cups, which presents different clearance and coverage angles. Predictable complications may occur, such as IPD, polyethylene wear and true dislocation. These complications have been reported at an even higher rate than they were in the eighties, when the first generation of DM implants were of a lower quality of polyethylene and the characteristic of the design was less optimal than modern ones.

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.

Dual Mobility for Monoblock Metal-on-Metal Revision-Is It Safe?

BACKGROUND

Revision of monoblock metal-on-metal (MoM) total hip arthroplasty (THA) is associated with high complication rates. Limited revision by conversion to a dual mobility (DM) without acetabular component extraction may mitigate these complications. However, the concern for polyethylene wear and osteolysis remains unsettled. This study investigates the results of DM conversion of monoblock MoM THA compared to formal acetabular revision.

METHODS

One hundred forty-three revisions of monoblock MoM THA were reviewed. Twenty-nine were revisions to a DM construct, and 114 were complete revisions of the acetabular component. Mean patient age was 61, 54% were women. Components used, acetabular cup position, radiographic outcomes, serum metal ion levels, and HOOS Jr clinical outcome scores were investigated.

RESULTS

At 3.9 years of follow-up (range 2-5), there were 2 revisions (6.9%) in the DM cohort, 1 for instability and another for periprosthetic fracture. Among the formal acetabular revision group there was a 20% major complication rate (23/114) and 16% underwent revision surgery (18/114) for aseptic loosening of the acetabular component (6%), deep infection (6%), dislocation (4%), acetabular fracture (3%), or delayed wound healing (6%). In the DM cohort, there were no radiographic signs of aseptic loosening, component migration, or polyethylene wear. One DM patient had a small posterior metadiaphyseal femur lesion that will require close monitoring. There were no other radiographic signs of osteolysis. There were no clinically significant elevations of serum metal ion levels. HOOS Jr scores were favorable.

CONCLUSION

Limited revision with conversion to DM is a viable treatment option for failed monoblock MoM THA with lower complication rates than formal revision. Limited revision to DM appears to be a safe option for revision of monoblock MoM THA with a cup in good position and an internal geometry free of sharp edges or articular surface damage. Longer follow-up is needed to demonstrate any potential wear implications of these articulations.

Predicting changes in the status of patient-reported outcome measures after Birmingham Hip Resurfacing: an observational cohort study with a median follow-up of ten years

AIMS

It is not known whether change in patient-reported outcome measures (PROMs) over time can be predicted by factors present at surgery, or early follow-up. The aim of this study was to identify factors associated with changes in PROM status between two-year evaluation and medium-term follow-up.

PATIENTS AND METHODS

Patients undergoing Birmingham Hip Resurfacing completed the Veteran's Rand 36 (VR-36), modified Harris Hip Score (mHHS), Tegner Activity Score, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at two years and a minimum of three years. A change in score was assessed against minimal clinically important difference (MCID) and patient-acceptable symptom state (PASS) thresholds. Binary logistic regression was used to assess the relationship between patient factors and deterioration in PASS status between follow-ups.

RESULTS

Overall, 18% of patients reported reductions in mHHS total score exceeding MCID, and 21% reported similar reductions for WOMAC function scores. Nonetheless, almost all patients remained above PASS thresholds for WOMAC function (98%) and mHHS (93%). Overall, 66% of patients with mHHS scores < PASS at two years reported scores > PASS at latest follow-up. Conversely, 6% of patients deteriorated from > PASS to < PASS between follow-ups. Multivariable modelling indicated body mass index (BMI) > 27 kg/m², VR-36 Physical Component Score (PCS) < 51, VR-36 Mental Component Score (MCS) > 55, mHHS < 84 at two years, female sex, and bone graft use predicted these deteriorating patients with 79% accuracy and an area under the curve (AUC) of 0.84.

CONCLUSION

Due to largely acceptable results at a later follow-up, extensive monitoring of multiple PROMs is not recommended for Birmingham Hip Resurfacing patients unless they report borderline or unacceptable hip function at two years, are female, are overweight, or received a bone graft during surgery. Cite this article: Bone Joint J 2019;101-B:1431-1437.

No added value for Computer-Assisted surgery to improve femoral component positioning and Patient Reported Outcomes in Hip Resurfacing Arthroplasty; a multi-center randomized controlled trial

Background

Computer Assisted Surgery (CAS) has proven to improve the accuracy in several orthopedic procedures. Therefore we used this technique to evaluate femoral component positioning in Hip Resurfacing Arthroplasty (HRA). The aim of this study was to evaluate imageless CAS compared to manually implanted femoral components and subsequently evaluates Patient Related Outcome Measures (PROMs). We hypothesized that the use of CAS optimizes the position of the femoral component and improves PROMs.

Methods

This is a multicenter, single-blinded, randomized, controlled trial of two groups. In the CAS group guiding of the femoral component was done with imageless navigation. In the Conventional (control) group the femoral component was placed manually according to the preplanned position. The primary outcome measure consists of a maximum of 3 degrees difference between the postoperative Stem Shaft Angle (SSA) and preplanned SSA. Secondary outcome measures consist of the Hip disability and Osteoarthritis Outcome Scale (HOOS), the Harris Hip Score (HHS) and Visual Analogue Scale (VAS) pain score.

Results

A total of 122 patients were randomized, 61 in the CAS group and 61 in the conventional group. There was no significant differences in accuracy of femoral implant position. The mean difference between the postoperative- and preplanned SSA was − 2.26 and − 1.75 degrees (more varus) respectively in the CAS and Conventional group. After surgery both groups show significant improvement in all PROMs compared to the baseline measurements, with no significant differences between the groups.

Conclusion

Our cohort indicates no benefit for the use of CAS in accuracy of placement of the femoral component in HRA compared to manual implantation. There are no clinical differences in PROMs after 1 year follow up. This study showed no added value and no justification for the use of CAS in femoral component positioning in HRA.

Trial registration

This trial is registered at ClinicalTrails.gov (https://clinicaltrials.gov/) on the 25th of October 2006: NCT00391937.

Level of incidence

Level IIb, multicenter randomized controlled trial.

Computer-assisted Navigation in Hip Resurfacing Arthroplasty: A Case Study utilizing the ReCap Femoral Resurfacing System

Introduction:

The ReCap Femoral Resurfacing System has been associated with increased cases of revision surgery when compared to other hip resurfacing systems. However, computer-assisted navigation may have the potential to reduce the risk of post-operative complications by providing more accurate intraoperative measurements for acetabular component positioning.

Case Report:

The present case describes an active 46-year-old male presenting with severe osteoarthritis of the right hip who elected to undergo a ReCap resurfacing arthroplasty with navigation. Results demonstrated accurate acetabular component position and leg length measurements to within <1° and 1mm of standard radiographic measurements.

Conclusion:

These findings are the first to describe the use of navigation with the ReCap system and provide encouraging results for further clinical evaluation.

Anatomic study on the blood supply to the femoral head following hip resurfacing using the posterior approach

OBJECTIVES

The aim of this study was to investigate femoral head perfusion following cadaveric hip resurfacing using the posterior approach.

METHODS

This cadaveric study involved injecting Higgins India ink into the common iliac arteries and evaluating the distribution of ink in the resurfaced heads using the modified Spalteholz technique. The study consisted of 2 parts. The 1st part involved utilisation of 22 cadaveric hips for establishing the injection and histological technique. The 2nd part of the study included 4 control cadaveric hips and 12 cadaveric hips with posterior approach hip resurfacing. Each specimen was divided into 15 zones (12 head zones and 3 neck zones) to evaluate detailed geographic distribution of dye-containing blood vessels.

RESULTS

All 4 controls had good flow of ink to all head zones and the neck region. In all the resurfaced heads, there was good flow to all the neck zones. 6 resurfaced specimens had no dye flow to any of the head zones. In the remaining 6, dye-stained vessels were seen variably in the anterior and middle zones but were consistently absent in the posterior zones of the head. Zones representing the antero-inferior parts of femoral head had the maximum flow of ink, followed by zones representing middle-inferior parts.

CONCLUSIONS

Posterior approach for hip resurfacing arthroplasty results in vascular insult to the femoral head, with posterior zones more affected than the anterior zones. The persistence of the dye in the intraosseous blood vessels of the neck and in anteroinferior head may be a source of revascularisation of the femoral head after posterior approach hip resurfacing.

10-year results of ReCap hip resurfacing arthroplasty: a non-designer case series

INTRODUCTION

We present the 10-year results of the ReCap Magnum HRA system in a consecutive single surgeon's series from a non-designer centre.

PATIENTS AND METHODS

Hip resurfacing arthroplasty (HRA) was performed in active males under 65 years and in pre-menopausal females with adequate bone density proven by a DEXA scan. Clinical follow-up; annual Oxford hip scoring, UCLA scoring and whole blood metal ion level measurement. Kaplan-Meier method was used to determine survivorship with revision as the end point. Radiographs were analysed for; acetabular inclination, notching, neck thinning and change in implant position. 72 HRAs were performed in 66 patients with a mean age of 45.7 years. The mean follow-up was 10.63 ± 0.54 years (range 10-11.75 years).

RESULTS

The survivorship of the cohort at minimum 10 years was 97.22% (95% confidence interval 94.14-99.01). There was a significant improvement in the Oxford Hip Score from 15.77 ± 4.33 to 45.67 ± 4.43 (p < 0.001) and the UCLA score from 3.14 ± 0.74 to 7.07 ± 1.16 (p < 0.001). Mean whole blood cobalt and chromium levels were 28.83 ± 8.42 nmol/l and 39.93 ± 9.64 nmol/l respectively. There were 2 revisions, due to avascular necrosis and implant failure. In our series the implant has performed well with <1% failure per year. We did not note any difference between the genders, since all the females in our series had been screened for osteopenia using a DEXA scan. All our patients returned to an active lifestyle which was maintained at final follow-up.

CONCLUSION

Strict selection criteria and a well-designed implant result in good long-term functional and radiological results with hip resurfacing.

Metal on Metal Hip Resurfacing in Patients 45 Years of Age and Younger at Minimum 5-Year Follow-Up

BACKGROUND

Metal on metal hip resurfacing (MoM-HR) is an alternative to total hip arthroplasty in young and active patients. The purpose was to determine the survivorship of MoM-HR procedures performed in patients aged 45 years and younger assessing patient-reported outcome measures (PROMs) at minimum 5-year follow-up.

METHODS

All 217 patients equal to or younger than 45 years of age at the time of surgical intervention presenting to our center with MoM-HR between May 2002 and May 2011 were prospectively followed. Baseline demographic data, preoperative and postoperative radiographic measurements, and validated PROMs were obtained (Hip Disability and Osteoarthritis Outcome Score, Western Ontario and McMaster Universities Osteoarthritis Index, and University of California, Los Angeles Activity Score). Survivorship was calculated using Kaplan-Meier analysis, and risk factors for failure were identified using multivariate regression analysis.

RESULTS

The overall survivorship excluding septic failures was 94.6% and 93.8% at 5 and 10 years, respectively. Aseptic loosening of the acetabular component was the most common mode of failure (11/20 cases). Gender, head size, and acetabular abduction angle had no significant effect on survivorship. Significant improvements in PROMs were seen for Hip Disability and Osteoarthritis Outcome Score, Western Ontario and McMaster Universities Osteoarthritis Index, and University of California, Los Angeles Activity Scale (P < .001).

CONCLUSION

This study indicates that MoM-HR is a suitable option for young individuals, as demonstrated through improved functional scores and low revision rates. The survivorship of HR in the younger than 45 age-group was similar to that of total hip arthroplasty, as well as HR in older patients. Given the proposed benefits of HR, this procedure may be viewed as a viable option in patients aged younger than 45 years.

Long - term survivorship and clinical results of the navigated withdrawn ASR ™

Introduction

Primary goals of the study were to present the mid - to long - term survivorship and clinical, radiological and metal serological results of the first stem - navigated ASR™ resurfacing at our clinic. Secondary goals were to determine the influence of stem - navigation on the outcome and risk factors for revision in our cohort.

Methods

From Mai 2006 to Mai 2009 46 ASR™ resurfacing hip systems have been implanted in 43 patients with a median age of 55 years. At final follow - up (33 patients with a mean follow -up of 89,6 months) guidelines were followed and HHS and HOOS were completed. Inclination, NSA and SSA were measured on radiographs and signs of loosening were graded. Risk factors for revision were compared in the non - revision and revision group.

Results

Mean cumulative survival of the prosthesis after 99,9 Months was 81,8%. At final follow - up 8 revisions were performed. Median HHS was 97, HOOS was 87,2. Four prostheses showed signs of loosening and nine heterotopic ossifications. All shaft components, except one, were placed in minimal valgus position to avoid risk for fracture. Age and diameter of the femoral component were significantly different between the non - revision and revision group.

Discussion

Survivorship is comparable to numbers found in other studies. Patients with complete final follow - up in general had good objective and subjective scores and few signs of loosening in the radiological follow - up. Navigation might have a positive effect on reduction of risk for fracture. Age and diameter of the femoral component seem to influence the outcome.

Indications for MARS-MRI in Patients Treated With Articular Surface Replacement XL Total Hip Arthroplasty

BACKGROUND

The purpose of this study was to identify which patient and clinical factors are predictive of adverse local tissue reaction (ALTR) and to use these factors to create a highly sensitive algorithm for indicating metal artifact reduction sequence magnetic resonance imaging (MARS-MRI) in Articular Surface Replacement (ASR) XL total hip arthroplasty patients. Our secondary aim was to compare our algorithm to existing national guidelines on when to take MARS-MRI in metal-on-metal total hip arthroplasty patients.

METHODS

The study consisted of 137 patients treated with unilateral ASR XL implants from a prospective, multicenter study. Patients underwent MARS-MRI regardless of clinical presentation at a mean of 6.2 (range, 3.3-10.4) years from surgery. Univariate and multivariate analyses were conducted to determine which variables were predictive of ALTR. Predictors were used to create an algorithm to indicate MARS-MRI. Finally, we compared our algorithm's ability to detect ALTR to existing guidelines.

RESULTS

We found a visual analog scale pain score ≥2 (odds ratio [OR] = 2.53; P = .023), high blood cobalt (OR = 1.05; P = .023), and male gender (OR = 2.37; P = .034) to be significant predictors of ALTR presence in our cohort. The resultant algorithm achieved 86.4% sensitivity and 60.2% specificity in detecting ALTR within our cohort. Our algorithm had the highest area under the curve and was the only guideline that was significantly predictive of ALTR (P = .014).

CONCLUSION

Our algorithm including patient-reported pain and sex-specific cutoffs for blood cobalt levels could predict ALTR and indicate MARS-MRI in our cohort of ASR XL metal-on-metal patients with high sensitivity.

LEVEL OF EVIDENCE

Level II, diagnostic study.

Trabecular Metal Versus Non-Trabecular Metal Acetabular Components and the Risk of Re-Revision Following Revision Total Hip Arthroplasty: A Propensity Score-Matched Study from the National Joint Registry for England and Wales

BACKGROUND

Studies have suggested that Trabecular Metal (TM)-coated acetabular components may reduce implant failure following revision total hip arthroplasty. However, these studies have predominantly been limited to small, single-center cohorts, with many lacking a comparator group. Using National Joint Registry data from England and Wales, we compared re-revision rates following revision total hip arthroplasty between TM and non-TM-coated acetabular components from 1 manufacturer.

METHODS

This retrospective observational study included all revision total hip arthroplasties performed with use of 1 of 4 cementless acetabular components produced by the same manufacturer (Zimmer Biomet). The acetabular components either had a TM surface coating (TM Modular and Continuum designs) or a non-TM surface coating (Trilogy and Trilogy IT designs). Revision total hip arthroplasties with TM and non-TM implants were matched for multiple potential patient and surgical confounding factors using propensity scores. Outcomes following revision total hip arthroplasty (re-revision for all acetabular indications, aseptic acetabular loosening, or infection) were compared between matched groups using competing risk regression analysis. Analyses were repeated in a subgroup initially revised for infection.

RESULTS

Of 3,862 matched revision total hip arthroplasties (1,931 in the TM group and 1,931 in the non-TM group), the overall prevalence of acetabular re-revision (2.7%; 95% confidence interval [CI] = 2.1% to 3.2%), re-revision for aseptic acetabular loosening (0.96%; 95% CI = 0.68% to 1.3%), and re-revision for infection (1.4%; 95% CI = 1.0% to 1.8%) were low. Six-year rates of re-revision for all causes (subhazard ratio [SHR] = 0.91; 95% CI = 0.61 to 1.35; p = 0.636), aseptic acetabular loosening (SHR = 1.32; 95% CI = 0.68 to 2.53; p = 0.410), and infection (SHR = 0.68; 95% CI = 0.39 to 1.20; p = 0.165) were similar between revision total hip arthroplasties with TM and non-TM coatings. Of 247 total hip arthroplasties initially revised for infection (116 TM and 131 non-TM), the rates of re-revision for all causes (SHR = 0.48; 95% CI = 0.15 to 1.56; p = 0.225), aseptic acetabular loosening (SHR = 0.54; 95% CI = 0.05 to 5.74; p = 0.608), and infection (SHR = 0.82; 95% CI = 0.28 to 2.36; p = 0.706) were similar between the TM and non-TM groups.

CONCLUSIONS

Following revision total hip arthroplasty, TM-coated acetabular components had a low risk of both aseptic and septic re-revision, with rates that were comparable with those of non-TM components. Extended follow-up of large revision total hip arthroplasty cohorts will establish whether TM components have any clinical benefit over non-TM designs when used in patients with similar acetabular bone stock.

LEVEL OF EVIDENCE

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

Indications for MARS-MRI in Patients Treated With Metal-on-Metal Hip Resurfacing Arthroplasty

BACKGROUND

Currently, there are no universally accepted guidelines on when to obtain metal artifact reduction sequence magnetic resonance imaging (MARS-MRI) in metal-on-metal (MoM) hip resurfacing arthroplasty (HRA) patients. Our primary aims were to identify which patient and clinical factors are predictive of adverse local tissue reaction (ALTR) and create an algorithm for indicating MARS-MRI in patients with Articular Surface Replacement (ASR) HRA. The secondary aim was to compare our algorithm to existing guidelines on when to perform MARS-MRI in MoM HRA patients.

METHODS

The study cohort consisted of 182 patients with unilateral ASR HRA from a prospective, multicenter study. Subjects received MARS-MRI at a mean of 7.8 years from surgery, regardless of symptoms. We determined which variables were predictive of ALTR and generated cutoffs for each variable. Finally, we created an algorithm to predict ALTR and indicate MARS-MRI in ASR HRA patients using these cutoffs and compared it to existing guidelines.

RESULTS

We found high blood cobalt (Co) (odds ratio = 1.070; P = .011) and high blood chromium (Cr) (odds ratio = 1.162; P = .002) to be significant predictors of ALTR presence. Our algorithm using a blood Co cutoff of 1.15 ppb and a Cr cutoff of 1.09 ppb achieved 96.6% sensitivity and 35.3% specificity in predicting ALTR, which outperformed the existing guidelines.

CONCLUSION

Blood Co and Cr levels are predictive of ALTR in ASR HRA patients. Our algorithm considering blood Co and Cr levels predicts ALTR in ASR HRA patients with higher sensitivity than previously established guidelines.

Outcomes After Metal-on-metal Hip Revision Surgery Depend on the Reason for Failure: A Propensity Score-matched Study

BACKGROUND

Metal-on-metal hip replacement (MoMHR) revision surgery for adverse reactions to metal debris (ARMD) has been associated with an increased risk of early complications and reoperation and inferior patient-reported outcome scores compared with non-ARMD revisions. As a result, early revision specifically for ARMD with adoption of a lower surgical threshold has been widely recommended with the goal of improving the subsequent prognosis after ARMD revisions. However, no large cohorts have compared the risk of complications and reoperation after MoMHR revision surgery for ARMD (an unanticipated revision indication) with those after non-ARMD revisions (which represent conventional modes of arthroplasty revision).

QUESTIONS/PURPOSES

(1) Does the risk of intraoperative complications differ between MoMHRs revised for ARMD compared with non-ARMD indications? (2) Do mortality rates differ after MoMHRs revised for ARMD compared with non-ARMD indications? (3) Do rerevision rates differ after MoMHRs revised for ARMD compared with non-ARMD indications? (4) How do implant survival rates differ after MoMHR revision when performed for specific non-ARMD indications compared with ARMD?

METHODS

This retrospective observational study involved all patients undergoing MoMHR from the National Joint Registry (NJR) for England and Wales subsequently revised for any indication between 2008 and 2014. The NJR achieves high levels of patient consent (93%) and linked procedures (ability to link serial procedures performed on the same patient and hip; 95%). Furthermore, recent validation studies have demonstrated that when revision procedures have been captured within the NJR, the data completion and accuracy were excellent. Revisions for ARMD and non-ARMD indications were matched one to one for multiple potential confounding factors using propensity scores. The propensity score summarizes the many patient and surgical factors that were used in the matching process (including sex, age, type of primary arthroplasty, time to revision surgery, and details about the revision procedure performed such as the approach, specific components revised, femoral head size, bearing surface, and use of bone graft) using one single score for each revised hip. The patient and surgical factors within the ARMD and non-ARMD groups subsequently became much more balanced once the groups had been matched based on the propensity scores. The matched cohort included 2576 MoMHR revisions with each study group including 1288 revisions (mean followup of 3 years for both groups; range, 1-7 years). Intraoperative complications, mortality, and rerevision surgery were compared between matched groups using univariable regression analyses. Implant survival rates in the non-ARMD group were calculated for each specific revision indication with each individual non-ARMD indication subsequently compared with the implant survival rate in the ARMD group using Cox regression analyses.

RESULTS

There was no difference between the ARMD and non-ARMD MoMHR revisions in terms of intraoperative complications (odds ratio, 0.97; 95% confidence interval [CI], 0.59-1.59; p = 0.900). Mortality rates were lower after ARMD revision compared with non-ARMD revision (hazard ratio [HR], 0.43; CI, 0.21-0.87; p = 0.019); however, there was no difference when revisions performed for infection were excluded from the non-ARMD indication group (HR, 0.69; CI, 0.35-1.37; p = 0.287). Rerevision rates were lower after ARMD revision compared with non-ARMD revision (HR, 0.52; CI, 0.36-0.75; p < 0.001); this difference persisted even after removing revisions performed for infection (HR, 0.59; CI, 0.40-0.89; p = 0.011). Revisions for infection (5-year survivorship = 81%; CI, 55%-93%; p = 0.003) and dislocation/subluxation (5-year survivorship = 82%; CI, 69%-90%; p < 0.001) had the lowest implant survival rates when compared with revisions for ARMD (5-year survivorship = 94%; CI, 92%-96%).

CONCLUSIONS

Contrary to previous observations, MoMHRs revised for ARMD have approximately half the risk of rerevision compared with non-ARMD revisions. We suspect worldwide regulatory authorities have positively influenced rerevision rates after ARMD revision by recommending that surgeons exercise a lower revision threshold and that such revisions are now being performed at an earlier stage. The high risk of rerevision after MoMHR revision for infection and dislocation is concerning. Infected MoMHR revisions were responsible for the increased mortality risk observed after non-ARMD revision, which parallels findings in non-MoMHR revisions for infection.

LEVEL OF EVIDENCE

Level III, therapeutic study.

The risk of cardiac failure following metal-on-metal hip arthroplasty

AIMS

The aim of this study was to determine whether patients with metal-on-metal (MoM) arthroplasties of the hip have an increased risk of cardiac failure compared with those with alternative types of arthroplasties (non-MoM).

PATIENTS AND METHODS

A linkage study between the National Joint Registry, Hospital Episodes Statistics and records of the Office for National Statistics on deaths was undertaken. Patients who underwent elective total hip arthroplasty between January 2003 and December 2014 with no past history of cardiac failure were included and stratified as having either a MoM (n = 53 529) or a non-MoM (n = 482 247) arthroplasty. The primary outcome measure was the time to an admission to hospital for cardiac failure or death. Analysis was carried out using data from all patients and from those matched by propensity score.

RESULTS

The risk of cardiac failure was lower in the MoM cohort compared with the non-MoM cohort (adjusted hazard ratio (aHR) 0.901; 95% confidence interval (CI) 0.853 to 0.953). The risk of cardiac failure was similar following matching (aHR 0.909; 95% CI 0.838 to 0.987) and the findings were consistent in subgroup analysis.

CONCLUSION

The risk of cardiac failure following total hip arthroplasty was not increased in those in whom MoM implants were used, compared with those in whom other types of prostheses were used, in the first seven years after surgery. Cite this article: Bone Joint J 2018;100-B:20-7.

Intraoperative Complications and Mid-Term Follow-Up of Large-Diameter Head Metal-on-Metal Total Hip Arthroplasty and Hip Resurfacing Arthroplasty

BACKGROUND AND AIMS

Large-diameter head total hip arthroplasty and hip resurfacing arthroplasty were popular in Finland from 2000 to 2012 for the treatment of hip osteoarthritis. The aim of this retrospective study was to investigate the mid-term survival of large-diameter head total hip arthroplasty patients operated on in three university hospitals and to compare these results to the survival of hip resurfacing arthroplasty patients.

MATERIAL AND METHODS

A total of 3860 hip arthroplasties (3029 large-diameter head total hip arthroplasties in 2734 patients and 831 hip resurfacing arthroplasties in 757 patients) were operated on between January 2004 and December 2009. The mean follow-up was 4.3 years (range: 0.3-8.0 years) in the total hip arthroplasty group and 5.1 years (range: 1.7-7.9 years) in the hip resurfacing arthroplasty group. Cox multiple regression model and Kaplan-Meier survival analysis were used to study the survival of the total hip arthroplasties and the hip resurfacing arthroplasties. Intraoperative complications and reasons for revisions were also evaluated.

RESULTS

In Cox regression analysis, the hazard ratio for revision of hip resurfacing arthroplasty was 1.5 compared with large-diameter head total hip arthroplasty (95% confidence interval: 1.0-2.2) ( p = 0.029). The cumulative Kaplan-Meier survival rate was 90.7% at 7.7 years for the large-diameter head total hip arthroplasty (95% confidence interval: 86.8-94.6) and 92.2% at 7.6 years for hip resurfacing arthroplasty (95% confidence interval: 89.9-94.6). There were a total of 166/3029 (5.5%) intraoperative complications in the large-diameter head total hip arthroplasty group and 20/831 (2.4%) in the hip resurfacing arthroplasty group ( p = 0.001). Revision for any reason was performed on 137/3029 (4.5%) of the arthroplasties in the large-diameter head total hip arthroplasty group and 52/831 (6.3%) in the hip resurfacing arthroplasty group ( p = 0.04).

CONCLUSION

The mid-term survival of both of these devices was poor, and revisions due to adverse reactions to metal debris will most likely rise at longer follow-up. There were more intraoperative complications in the large-diameter head total hip arthroplasty group than in the hip resurfacing arthroplasty group.

10-year results of the Birmingham Hip Resurfacing: a non-designer case series

INTRODUCTION

Recent controversies surrounding metal-on-metal (MoM) hip resurfacing has led to a substantial decline in its use. Despite this, there is good evidence to support the use of specific implants in select patients.

PATIENTS AND METHODS

A retrospective analysis of Birmingham Hip Resurfacing (BHR) patients with a minimum of 10 years follow-up was performed. Functional scoring was performed with the Oxford Hip Score (OHS) and failure was defined as revision for any cause. 111 patients underwent 121 BHR procedures. All patients had a minimum follow-up of 10 years. 70 patients (63%) were male. Mean patient age at surgery was 52.5 years (male 53.9 years, female 48.8 years).

RESULTS

Overall survival at 10 years was 91% (97% male, 80% female). There was a statistically significant improvement in OHS postoperatively which remains at 10-year follow-up (p = <0.05). There was no significant difference in scores between the male and female groups. Revisions were most often in patients with smaller component sizes but this was not found to be statistically significant.

CONCLUSIONS

Our results reflect that of the wider literature in that good outcomes can be obtained with this implant in a select group of patients and results are comparable to that of conventional hip arthroplasty in patients of a similar age.

Hard Chrome-Coated and Fullerene-Doped Metal Surfaces in Orthopedic Bearings

Metal-on-metal bearings for total hip replacements have been introduced as an alternative to polyethylene in young and more active patients. These have, however, been shown to be prone to implant malpositioning and have been limited by some specific design features. In that context, coatings present an option to increase wear resistance by keeping the high fracture strength of the metal substrate. A custom-made electroplating setup was designed for the coating of CoCr substrates using (a) an industrial standard chromium electrolyte; (b) a custom-made hexavalent chromium (Cr⁶⁺) electrolyte with a reduced chromium trioxide (CrO₃) content, both without solid additives and (c) with the addition of fullerene (C₆₀) nanoparticles; and (d) a trivalent chromium (Cr³⁺) electrolyte with C₆₀ addition. All coatings showed an increase in microhardness compared with the metal substrate. Trivalent coatings were thinner (10 µm) than the hexavalent coatings (23–40 µm) and resulted in increased roughness and crack density. Wear was found to be reduced for the hexavalent chromium coatings by 70–84% compared with the CoCr–CoCr reference bearing while the trivalent chromium coating even increased wear by more than 300%. The addition of fullerenes to the electrolyte did not show any further tribological effect.

Microstructure and Surface Damage in Retrieved Metal-on-Metal Hip Arthroplasties

BACKGROUND

Besides promising results of metal-on-metal (MOM) hip arthroplasty (HA), frequent failures have been reported even in the short term. Many host, surgical, design, metallurgical, and processing factors have been evoked in the base of these events. We have tried to characterize and to evaluate metallurgical and processing features present in this type of implants.

METHODS

The acetabular and femoral components of 20 MOM HAs collected from a multicenter retrieval program were examined. All the specimens were inspected with naked eye, with confocal microscopy and vertical scanning interferometry, scanning electron microscopy, back-scattered electron imaging, and energy-dispersive X-ray spectroscopy, in 25 zones of each articular component.

RESULTS

Gas pores, shrinkage voids and holes of detached carbides, carbides on surface, embedded particles, scratches and marks of wear, surface discoloration, surface deposits, and tribochemical reaction layers were widely dispersed through a substantial percentage of the total bearing surface in all the implanted components. Surface cup and head voids, and cup scratches showed significant correlation with the clearance of pair. A higher surface damage of the cup and head was observed mainly in the low clearance prostheses. There was no other significant correlation or difference in the incidence and importance of any of these defects between resurfacing hip arthroplasties and total hip arthroplasties, or according to the pair diameter.

CONCLUSION

Some metallurgical features and surface damage were significantly present in the retrieved implants of MoM HAs. It would be desirable to improve the structure and metallurgical characteristics of these implants to avoid those effects and optimize their performance.

Equal Primary Fixation of Resurfacing Stem, but Inferior Cup Fixation With Anterolateral vs Posterior Surgical Approach. A 2-Year Blinded Randomized Radiostereometric and Dual-energy X-Ray Absorptiometry Study of Metal-on-Metal Hip Resurfacing Arthroplasty

BACKGROUND

The anterolateral (AntLat) surgical approach may spare the blood supply to the femoral head and improve the accuracy of cup positioning in metal-on-metal hip resurfacing arthroplasty. Thereby, potentially lessen complications such as avascular head necrosis, femoral neck narrowing and fracture, improve implant fixation, and lessen periprosthetic bone mineral density (BMD) loss.

METHODS

Between November 2008 and January 2012, a randomized clinical trial was performed at Aarhus University Hospital. A total of 49 patients (28 males) were allocated to metal-on-metal hip resurfacing arthroplasty by the AntLat (n = 25) or the posterior (Post; n = 24) surgical approach. Patients were followed with radiostereometric analysis, measurements of periprosthetic BMD, clinical outcome scores of Harris hip score and visual analogue scale, serum metal ions, and conventional radiographs.

RESULTS

At 3 months, cups in the AntLat group had higher total translations of mean 1.00 ± 0.70 mm vs mean 0.64 ± 0.45 mm in the post group (P = .04), and higher total rotations of mean 2.44° ± 1.36° vs mean 1.39° ± 1.17° in the Post group (P = .002). All migrations of cup and stem were similar at 1 and 2 years postoperative (P > .07). At 1 year, periprosthetic BMD since postoperative at the medial side of the stem was reduced to mean 98.45% ± 8.57% in the AntLat group, and increased to mean 105.57% ± 11.07% in the Post group (P = .02), but measurements were comparable at 2 years (P = .05).

CONCLUSION

Cups inserted by the AntLat approach migrated more until 3 months postoperative. This illustrates a less good primary cup fixation with the AntLat approach; however, all cups were well-fixed after 3 months' follow-up indicating a good secondary fixation.

Lower limb arthroplasty: can we produce a tool to predict outcome and failure, and is it cost-effective? An epidemiological study

Background

Although hip and knee arthroplasties are considered to be common elective cost-effective operations, up to one-quarter of patients are not satisfied with the operation. A number of risk factors for implant failure are known, but little is known about the predictors of patient-reported outcomes.

Objectives

(1) Describe current and future needs for lower limb arthroplasties in the UK; (2) describe important risk factors for poor surgery outcomes and combine them to produce predictive tools (for hip and knee separately) for poor outcomes; (3) produce a Markov model to enable a detailed health economic analysis of hip/knee arthroplasty, and for implementing the predictive tool; and (4) test the practicality of the prediction tools in a pragmatic prospective cohort of lower limb arthroplasty.

Design

The programme was arranged into four work packages. The first three work packages used the data from large existing data sets such as Clinical Practice Research Datalink, Hospital Episode Statistics and the National Joint Registry. Work package 4 established a pragmatic cohort of lower limb arthroplasty to test the practicality of the predictive tools developed within the programme.

Results

The estimated number of total knee replacements (TKRs) and total hip replacements (THRs) performed in the UK in 2015 was 85,019 and 72,418, respectively. Between 1991 and 2006, the estimated age-standardised rates (per 100,000 person-years) for a THR increased from 60.3 to 144.6 for women and from 35.8 to 88.6 for men. The rates for TKR increased from 42.5 to 138.7 for women and from 28.7 to 99.4 for men. The strongest predictors for poor outcomes were preoperative pain/function scores, deprivation, age, mental health score and radiographic variable pattern of joint space narrowing. We found a weak association between body mass index (BMI) and outcomes; however, increased BMI did increase the risk of revision surgery (a 5-kg/m2rise in BMI increased THR revision risk by 10.4% and TKR revision risk by 7.7%). We also confirmed that osteoarthritis (OA) severity and migration pattern of the hip predicted patient-reported outcome measures. The hip predictive tool that we developed performed well, with a correctedR2of 23.1% and had good calibration, with only slight overestimation of Oxford Hip Score in the lowest decile of outcome. The knee tool developed performed less well, with a correctedR2of 20.2%; however, it had good calibration. The analysis was restricted by the relatively limited number of variables available in the extant data sets, something that could be addressed in future studies. We found that the use of bisphosphonates reduced the risk of revision knee and hip surgery by 46%. Hormone replacement therapy reduced the risk by 38%, if used for at least 6 months postoperatively. We found that an increased risk of postoperative fracture was prevented by bisphosphonate use. This result, being observational in nature, will require confirmation in a randomised controlled trial. The Markov model distinguished between outcome categories following primary and revision procedures. The resulting outcome prediction tool for THR and TKR reduced the number and proportion of unsatisfactory outcomes after the operation, saving NHS resources in the process. The highest savings per quality-adjusted life-year (QALY) forgone were reported from the oldest patient subgroups (men and women aged ≥ 80 years), with a reported incremental cost-effectiveness ratio of around £1200 saved per QALY forgone for THRs. In the prospective cohort of arthroplasty, the performance of the knee model was modest (R2 = 0.14) and that of the hip model poor (R2 = 0.04). However, the addition of the radiographic OA variable improved the performance of the hip model (R2 = 0.125 vs. 0.110) and high-sensitivity C-reactive protein improved the performance of the knee model (R2 = 0.230 vs. 0.216). These data will ideally need replication in an external cohort of a similar design. The data are not necessarily applicable to other health systems or countries.

Conclusion

The number of total hip and knee replacements will increase in the next decade. High BMI, although clinically insignificant, is associated with an increased risk of revision surgery and postoperative complications. Preoperative pain/function, the pattern of joint space narrowing, deprivation index and level of education were found to be the strongest predictors for THR. Bisphosphonates and hormone therapy proved to be beneficial for patients undergoing lower limb replacement. The addition of new predictors collected from the prospective cohort of arthroplasty slightly improved the performance of the predictive tools, suggesting that the potential improvements in both tools can be achieved using the plethora of extra variables from the validation cohort. Although currently it would not be cost-effective to implement the predictive tools in a health-care setting, we feel that the addition of extensive risk factors will improve the performances of the predictive tools as well as the Markov model, and will prove to be beneficial in terms of cost-effectiveness. Future analyses are under way and awaiting more promising provisional results.

Future work

Further research should focus on defining and predicting the most important outcome to the patient.

Funding

The National Institute for Health Research Programme Grants for Applied Research programme.

Birmingham Hip Resurfacing in Patients 55 Years or Younger: Risk Factors for Poor Midterm Outcomes

BACKGROUND

Birmingham hip resurfacing (BHR) is the only Food and Drug Administration-approved hip resurfacing system available in the United States and is used as an alternative to conventional total hip arthroplasty in younger patients. The purpose of this study is to report on the midterm outcomes of BHR in patients 55 years and younger, and specifically to examine the risk factors for aseptic failure, all-cause revision, and complications in this patient population.

METHODS

Four hundred forty-two consecutive patients with 5-year follow-up were retrospectively reviewed. Multivariate analyses were conducted to control for potential confounding factors identified by univariate analyses.

RESULTS

Mean follow-up was 71.68 ± 10.24 months. Among the potential risk factors, only female gender and smaller head sizes had a significant univariate relationship with aseptic revision, all-cause revision, and all-cause complications. When both risk factors were included in a multivariable logistic regression model, analyses showed both variables were closely related, with female gender a better predictor of adverse outcomes than head size (ie, small head size can be thought of as a proxy for female gender). The 5-year implant survival is 95.1% females compared to 99.0% in males.

CONCLUSION

Hip resurfacing with BHR has excellent survival rates in young patients with degenerative hip disease. Although this study suggests that females with small templated head sizes may not be suitable candidates for BHR, further studies are needed to better understand the underlying differences in gender.

Outcome of revision arthroplasty for failed metal-on-metal total hip replacements; is there a relation with metal ions?

PURPOSE

We aimed to assess the early outcome following revision arthroplasty for failed metal-on-metal (MoM) total hip replacements (THR) due to adverse reaction to metal debris (ARMD).

METHODS

We reviewed 106 consecutive revision arthroplasties. Case notes and radiological investigations were reviewed to assess the complications. Oxford Hip Score (OHS) and Euroqol (EQ-5D-3L) scores were used to assess the functional outcome and improvement of quality of life.

RESULTS

At a mean follow-up of 20 months (12-48 months), the mean OHS was 28.7. Pain improved in 61% patients. A majority of patients were in level 2 for all the EQ-5D-3L dimensions. The overall complication rate was 16%. Survivorship free from further revision for any cause was 94.3% at 48 months. There was no correlation between pre-revision blood metal ions and the final outcome.

CONCLUSIONS

Revision surgery for failed MoM hip replacement due to ARMD is associated with a relatively higher rate of complications and risk of chronic pain. There is poor correlation between serum metal ions and development of ARMD and outcome following revision surgery.

Pseudotumour formation and subsequent resolution in metal-on-metal total hip arthroplasty following revision: Instructional review and an illustrative case report with revision using a dual mobility design

The use of large-diameter metal-on-metal (MoM) components in total hip arthroplasty (THA) is associated with an increased risk of early failure due to adverse local tissue reaction to metal debris (ARMD) in response to the release of metal ions from the bearing couple and/or head-neck taper corrosion. The aim of this paper was to present a review of the incidence and natural history of ARMD and the forms of treatment, with a focus on the need for and extent of resection or debulking of the pseudotumour. An illustrative case report is presented of a patient with an intra-pelvic pseudotumour associated with a large diameter MoM THA, which was treated successfully with revision of the bearing surface to a dual mobility couple and retention of the well-fixed acetabular and femoral components. The pseudotumour was left in situ Resolution of the intra-pelvic mass and normalisation of metal ion levels was observed seven months post-operatively. Cite this article: Bone Joint J 2016;98-B:736-40.

Outcomes of the Recalled Articular Surface Replacement Metal-on-Metal Hip Implant System: A Systematic Review

BACKGROUND

The aim of this review was to synthesize the main findings of clinical studies that have evaluated outcomes of the articular surface replacement (ASR) Hip System.

METHODS

We performed a systematic literature search to identify all articles published between January 2008 and June 2015 that included ASR hip resurfacing arthroplasty (ASR HRA) or ASR total hip arthroplasty (ASR XL THA) outcomes according to the PRISMA statement.

RESULTS

A total of 56 studies were assessed. The prevalence of adverse local tissue reactions (ALTRs) and revision rates were found to be high. ALTR prevalence varied from 12.5% to 69% (mean, 33.5%). Mean revision rate for any reason at 4-year to 7-year follow-up was 13.8% (range, 5.6%-31%) for ASR HRA and 14.5% (range, 0%-37%) for ASR XL THA. Femoral head size <53 mm was found to correlate with higher blood metal ion levels. Femoral head size >44 mm was not associated with higher ALTR prevalence or revision rates in ASR XL THA. High blood metal ion levels (>7 μg/L Co, >7 μg/L Cr) were associated with higher failure rates and bearing-related complications. The role of cup positioning was found to be controversial.

CONCLUSION

ALTR prevalence and failure rates were high. High blood metal ion levels were a risk factor for ALTR and failure. Surprisingly, the role of cup positioning and large femoral head size in ASR XL THA were controversial. These findings should be considered in the clinical follow-up and risk stratification of patients with the ASR Hip System.

Comparison of Complications Following Revision of Metal-on-Metal Versus Metal-on-Polyethylene Total Hip Arthroplasty

The aim of this study was to examine the clinical characteristics of patients who required revision and the rate of early complications after revision for metal-on-metal total hip arthroplasty (MOM THA) and metal-on-polyethylene total hip arthroplasty (MOP THA). Matched cohorts were selected by retrospective review from a single-center database of revision THAs for failed MOM and MOP THAs from 2010 to 2014. A total of 140 hips in 140 patients comprised the study population; 39 revisions were performed for failed MOM THAs (MOM group), and 101 revisions were performed for failed MOP THAs (MOP group). Data included patient demographics, reason for revision, type of revision procedure, any complication within 90 days after surgery, admission type, and discharge disposition. Primary diagnosis, time from primary THA to revision, operative time, blood loss, and length of stay were reviewed. The analysis showed the time from the index primary procedure to first revision was earlier (P=.01) in the MOM group despite no significant intergroup differences in age, gender, primary diagnosis, or body mass index. Surgical morbidity, as indicated by operative time, blood loss, and length of stay, was lower in the MOM group. The stem was retained more often in the MOM group. There was no significant difference between the groups in overall complication rate. These findings indicate that when performed at an earlier time period before extensive soft tissue reaction to metal ions, revision following MOM THA is not associated with an increased complication rate compared with revision following MOP THA. [Orthopedics. 2017; 40(1):e164-e169.].

Has Metal-On-Metal Resurfacing Been a Cost-Effective Intervention for Health Care Providers?-A Registry Based Study

Background

Total hip replacement for end stage arthritis of the hip is currently the most common elective surgical procedure. In 2007 about 7.5% of UK implants were metal-on-metal joint resurfacing (MoM RS) procedures. Due to poor revision performance and concerns about metal debris, the use of RS had declined by 2012 to about a 1% share of UK hip procedures. This study estimated the lifetime cost-effectiveness of metal-on-metal resurfacing (RS) procedures versus commonly employed total hip replacement (THR) methods.

Methodology/Principal Findings

We performed a cost-utility analysis using a well-established multi-state semi-Markov model from an NHS and personal and social services perspective. We used individual patient data (IPD) from the National Joint Registry (NJR) for England and Wales on RS and THR surgery for osteoarthritis recorded from April 2003 to December 2012. We used flexible parametric modelling of NJR RS data to guide identification of patient subgroups and RS devices which delivered revision rates within the NICE 5% revision rate benchmark at 10 years. RS procedures overall have an estimated revision rate of 13% at 10 years, compared to <4% for most THR devices. New NICE guidance now recommends a revision rate benchmark of <5% at 10 years. 60% of RS implants in men and 2% in women were predicted to be within the revision benchmark. RS devices satisfying the 5% benchmark were unlikely to be cost-effective compared to THR at a standard UK willingness to pay of £20,000 per quality-adjusted life-year. However, the probability of cost effectiveness was sensitive to small changes in the costs of devices or in quality of life or revision rate estimates.

Conclusion/Significance

Our results imply that in most cases RS has not been a cost-effective resource and should probably not be adopted by decision makers concerned with the cost effectiveness of hip replacement, or by patients concerned about the likelihood of revision, regardless of patient age or gender.

Are Females at Greater Risk for Revision Surgery After Hip Resurfacing Arthroplasty With the Articular Surface Replacement Prosthesis?

BACKGROUND

Female patients undergoing hip resurfacing arthroplasties may be at greater risk of revision surgery than males, but it is unclear whether this is related to sex or other factors. We focused our analysis on data from a prospective multicenter cohort study monitoring the ASR(TM) hip resurfacing arthroplasty prosthesis on the potential association of sex on patient-reported outcome measures (PROMs), metal ion levels, revision surgery, and presence of adverse local tissue reaction. As thousands of patients with the ASR(TM) prosthesis are still undergoing followup it is critical to optimize the protocol for monitoring these patients.

QUESTIONS/PURPOSES

We wished (1) to assess the associations between sex and implant survival, and adverse local tissue reaction; and (2) to report the differences between sexes in metal ion levels and patient-reported outcome measures.

METHODS

One thousand two hundred fifty-two patients (1390 hips) who underwent hip resurfacing arthroplasty with implantation of the ASR(TM) prosthesis from April 2003 to July 2010 were eligible for enrollment in a multicenter followup study of the ASR(TM) Hip Resurfacing System after the voluntary recall of this device was initiated by DePuy in 2010. Nine hundred seventy patients (1098 hips) were enrolled at a mean of 7 years after surgery, with a mean followup of 2 years (range, 1-3.5 years). Nine hundred fifty-eight patients (1084 hips) met the inclusion criteria: ability to provide informed consent, complete PROMs, and continued routine followup. A subset of patients (150 patients, 171 hips), who all were from one center, with annual metal artifact reduction sequence MRI were analyzed. Ninety-three percent of patients from this center had routine MRI performed. The EuroQoL (EQ-5D), Harris hip score (HHS), University of California Los Angeles (UCLA) activity score, VAS pain, radiographs, patient and surgery details, and blood cobalt and chromium levels were obtained. Cox regression analysis was conducted to identify factors associated with implant survival, using any revision as the end point, and presence of adverse local tissue reaction.

RESULTS

In patients who had unilateral surgery, the only variable found to be associated with revision surgery was HHS (hazard ratio [HR], 0.96; 95% CI, 0.94-0.97; p < 0.001). In patients who had bilateral surgery, only HHS (HR, 0.93; 95% CI, 0.90-0.97; p < 0.001) and cobalt level (HR, 1.02; 95% CI, 1.01-1.03; p < 0.001) were associated with risk for revision. In patients with metal artifact reduction sequence MRI, the only variable found to be associated with presence of adverse local tissue reaction was cobalt level (HR, 1.06; 95% CI, 1.02-1.10; p = 0.001). Cobalt and chromium concentrations were greater in female patients than in male patients (cobalt, median 1.89 versus median 1.12 parts per billion [ppb], p < 0.001; chromium, median 2.03 versus median 1.17 ppb, p < 0.001). Slight differences were observed between males and females in HHS (males median 96 versus females median 94, p < 0.001) and UCLA scores (median 8 versus median 6, p < 0.001); however, there was no difference between sexes for VAS pain (median 0.5 versus median 0.5, p = 0.405). Differences were identified between males and females in the distribution of EQ-5D scores, yet the medians were the same (median 1.0 versus median 1.0, p < 0.001).

CONCLUSIONS

Male and female patients who had hip resurfacing arthroplasty with implantation of the ASR(TM) prosthesis should be followed with equal vigilance as both are at similar risk of revision surgery and adverse local tissue reaction. Metal ion levels and HHS should be obtained at followup to monitor for risk of revision and as a screening tool for MRI. Further research is necessary to evaluate if these relationships persist in patients with other metal-on-metal prostheses.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Functional outcomes of total hip arthroplasty in patients aged 30 years or less: a systematic review and meta-analysis

INTRODUCTION

Young adult hip surgery is a growing subspecialty. Increasingly total hip arthroplasty (THA) is offered to patients aged 30 or less suffering from end-stage hip arthropathy from a variety of congenital, developmental and acquired conditions. There is a paucity of evidence to advise such patients and surgeons alike on the functional outcomes of THA in this age group, as individual studies tend to include small cohorts.

METHODS

A systematic review and meta-analysis was performed to assess whether THA in patients aged 30 years or less provides significant functional improvement. The primary outcome measure was change in Harris Hip Score. Secondary outcome measures were implant survivorship and the effect of fixation type and bearing surface.

RESULTS

The results of 743 primary THA procedures were included. Weighted mean patient age was 22.7 years. Harris Hip Score improved by a weighted mean difference of 42.17 points out of 100 (95% confidence interval, 36.48-47.86 points, p&lt;0.001) after THA at a weighted mean follow-up of 8.4 years. Pooled revision rate was 5.0% for the same time period.

CONCLUSIONS

This is the largest review to date of THA in patients aged 30 or less. The results show significant functional improvement measured by Harris Hip Score. The revision rate of 5% at 8.4 years is comparable to the general THA population. This contrasts high revision rates reported in older reviews of the literature, suggesting adoption of improved techniques and implants in the more recent literature.

Prevalence of and Risk Factors for Hip Resurfacing Revision: A Cohort Study Into the Second Decade After the Operation

BACKGROUND

Most metal-on-metal hip resurfacing (MoMHR) designs have experienced high short-term failure rates because of pseudotumors. The impact of this complication into the second decade after the procedure is unknown. We investigated (1) the prevalence of, and risk factors for, all-cause and pseudotumor-related revision at up to 15 years following MoMHR and (2) whether risk factors were sex-specific.

METHODS

This single-center prospective cohort study included 1,429 MoMHRs (1216 patients; 40% female) implanted between 1999 and 2009. Patients were contacted in 2010 and 2012 as per national recommendations. Patients with symptoms related to the hip and/or suboptimal Oxford Hip Scores (≤41 of 48 points) underwent cross-sectional imaging and blood metal-ion sampling. Revision diagnoses were established using operative and histopathological findings. Multivariate Cox proportional hazard models were used to assess the association of predictor variables with the time to all-cause and pseudotumor-related revisions.

RESULTS

One hundred and eighty MoMHRs (12.6%) were revised for all causes, and 111 (7.8% of the series and 61.7 % of all revisions) were revised because of pseudotumor. Survival analysis showed the 15-year cumulative revision rate for all causes to be 19.5% (95% confidence interval [CI] = 16.2% to 23.2%) and the 15-year rate of revision due to pseudotumor to be 14.0% (95% CI = 11.0% to 17.7%). Small femoral head size (hazard ratio [HR] per 2 mm = 0.92, 95% CI = 0.88 to 0.97; p = 0.003) and certain implant designs (HR = 1.55 to 3.01; p ≤ 0.029) significantly increased the all-cause revision risk. Female sex (HR = 2.03, 95% CI = 1.19 to 3.44; p = 0.009) and young age (HR per year = 0.98, 95% CI = 0.96 to 1.00; p = 0.020) significantly increased the pseudotumor-related revision risk but not the all-cause revision risk. Risk factors for all-cause and pseudotumor-related revision were sex-specific. In females, small femoral head size (p = 0.014) increased the all-cause revision risk, and young age was the only predictor of pseudotumor-related revision (p = 0.019). In males, implant design was the only predictor of all-cause revision (p ≤ 0.015) and pseudotumor-related revision (p = 0.001).

CONCLUSIONS

The prevalence and rates of revision for all causes and pseudotumor were high at up to 15 years following MoMHR. Predictors of revision differed between all-cause and pseudotumor-related revisions and were sex-specific. These factors must be appropriately weighted when risk-stratifying patients with MoMHRs for surveillance.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Systemic effects of cobalt toxicity after revision hip replacement can manifest in intermediate to long term follow-up

INTRODUCTION

Metal toxicity from metal-on-metal hip replacements is now well documented and several large series have reported local reactions. Although less common, there are reports of similar reactions from failed ceramic liners. Systemic effects documented in literature have been grouped into cardiac, neuro-ocular and thyroid signs.

METHODS AND RESULTS

We report a case of a patient who had revision for fractured ceramic liner to metal on polyethylene. Third body effect of the ceramic particles led to wear through of the poly liner and the head directly articulating with metal shell. He developed cardiac and neurological features of cobalt toxicity in addition to extensive soft tissue destruction. Revision of the bearing surfaces and synovectomy led to clinical improvement and fall in metal ion levels.

CONCLUSIONS

We recommend 2-stage revision in such situations and close monitoring of all these patients.

Hip resurfacing: history, current status, and future

Hip resurfacing arthroplasty (HRA) presents several advantages over conventional total hip arthroplasty (THA), including conservation and preservation of bone, reduced risk of dislocation, easy replication of hip biomechanics and easy revision if needed. It is a particularly appealing procedure for young patients. HRA has been performed for over 40 years following the same technological advances as THA. The bearing material used by most designs is metal-on-metal (MoM), which has the best compromise between strength and wear properties. However, MoM HRA has a specific set of possible complications. Aseptic femoral failures were initially the most prevalent cause for revision but progress in patient selection and surgical technique seem to have resolved this problem. Wear-related failures (high metal ion levels and adverse local tissue reactions) are now the main concern, and are essentially associated with poor acetabular component design and orientation, to which MoM is more sensitive than other bearing materials. The concept of functional coverage is key to understanding how MoM bearings are affected by edge wear. Only a 3-D assessment of cup position (e.g., the contact patch to rim distance) provides the necessary information to determine the role of cup positioning in relationship with abnormal bearing wear.The concept of hip resurfacing is more valid today than ever as the age of the patients in need of hip arthroplasty keeps getting lower. The recent publication of several excellent long-term survivorship results suggests that selection of a well-designed resurfacing system and accuracy in the placement of the cup can achieve long-term durability.

Salvage of Monoblock Metal-on-Metal Acetabular Components Using a Dual-Mobility Bearing

BACKGROUND

Large-diameter, monoblock acetabular components have been used for both hip resurfacing arthroplasty and metal-on-metal (MoM) total hip arthroplasty (THA). If revision is required, one solution is to retain the shell and use a dual-mobility bearing.

METHODS

We reviewed the results of 25 revision THAs including 11 hip resurfacing arthroplasty and 14 MoM THAs where a monoblock acetabular component was mated to a dual-mobility bearing.

RESULTS

At a mean of 29 months, there was one failure, an intraprosthetic dislocation of the dual-mobility bearing. There was a significant decrease in serum metal ion levels postoperatively.

CONCLUSION

Retention of a well-fixed, monoblock MoM acetabular shell and mating it to a dual-mobility bearing in the setting of revision surgery seems to be a reasonable, low-morbidity option at short-term follow-up in appropriately positioned cups.

High Re-Operation Rates Using Conserve Metal-On-Metal Total Hip Articulations

Introduction:

Metal-on-metal hip articulations have been intensely debated after reports of adverse reactions and high failure rates. The aim of this study was to retrospectively evaluate the implant of a metal-on.metal total hip articulation (MOM THA) from a single manufacture in a two-center study.

Materials and Methods:

108 CONSERVE^® MOM THA were implanted in 92 patients between November 2005 and December 2010. Patients had at time of retrospective evaluation their journals reviewed for re-operations and adverse reactions.

Results:

20 hips were re-operated (18.4%) at a mean follow up of 53 months. 4 pseudotumors were diagnosed at time of follow up but no substantiated link was made between adverse reactions and re-operations.

Conclusion:

The high re-operation rates found in this study raised concern about the usage of the MOM THA and subsequently lead to the termination of implantation of this MOM THA at the two orthopaedic departments.

Current indications for hip resurfacing arthroplasty in 2016

Hip resurfacing arthroplasty (HRA) is an alternative to conventional, stemmed total hip arthroplasty (THA). The best reported results are young, active patients with good bone stock and a diagnosis of osteoarthritis. Since the 1990s, metal-on-metal (MoM) HRA has achieved excellent outcomes when used in the appropriate patient population. Concerns regarding the metal-on-metal bearing surface including adverse local tissue reaction (ALTR) to metal debris have recently lead to a decline in the use of this construct. The current paper aims to provide an updated review on HRA, including a critical review of the most recent literature on HRA.