Can blood metal ion levels be used to identify patients with bilateral Birmingham Hip Resurfacings who are at risk of adverse reactions to metal debris?

AIMS: We investigated whether blood metal ion levels could effectively identify patients with bilateral Birmingham Hip Resurfacing (BHR) implants who have adverse reactions to metal debris (ARMD). PATIENTS AND METHODS: Metal ion levels in whole blood were measured in 185 patients with bilateral BHRs. Patients were divided into those with ARMD who either had undergone a revision for ARMD or had ARMD on imaging (n = 30), and those without ARMD (n = 155). Receiver operating characteristic analysis was used to determine the optimal thresholds of blood metal ion levels for identifying patients with ARMD. RESULTS: The maximum level of cobalt or chromium ions in the blood was the parameter which produced the highest area under the curve (91.0%). The optimal threshold for distinguishing between patients with and without ARMD was 5.5 µg/l (83.3% sensitivity, 88.4% specificity, 58.1% positive and 96.5% negative predictive values). Similar results were obtained in a subgroup of 111 patients who all underwent cross-sectional imaging. Between 3.2% and 4.3% of patients with ARMD were missed if United Kingdom (7 µg/l) and United States (10 µg/l) authority thresholds were used respectively, compared with 2.7% if our implant specific threshold was used, though these differences did not reach statistical significance (p ≥ 0.248). CONCLUSION: Patients with bilateral BHRs who have blood metal ion levels below our implant specific threshold were at low-risk of having ARMD. Cite this article: Bone Joint J 2016;98-B:1455-62.

The outcome of the Birmingham Hip Resurfacing in patients aged < 50 years up to 14 years post-operatively.

We report the long-term survival and functional outcome of the Birmingham Hip Resurfacing (BHR) in patients aged < 50 years at operation, and explore the factors affecting survival. Between 1997 and 2006, a total of 447 BHRs were implanted in 393 patients (mean age 41.5 years (14.9 to 49.9)) by one designing surgeon. The mean follow-up was 10.1 years (5.2 to 14.7), with no loss to follow-up. In all, 16 hips (3.6%) in 15 patients were revised, giving an overall cumulative survival of 96.3% (95% confidence interval (CI) 93.7 to 98.3) at ten years and 94.1% (95% CI 84.9 to 97.3) at 14 years. Using aseptic revision as the endpoint, the survival for men with primary osteoarthritis (n = 195) was 100% (95% CI 100 to 100) at both ten years and 14 years, and in women with primary osteoarthritis (n = 109) it was 96.1% (95% CI 90.1 to 99.9) at ten years and 91.2% (95% CI 68.6 to 98.7) at 14 years. Female gender (p = 0.047) and decreasing femoral head size (p = 0.044) were significantly associated with an increased risk of revision. The median Oxford hip score (OHS, modified as a percentage with 100% indicating worst outcome) at last follow-up was 4.2% (46 of 48; interquartile range (IQR) 0% to 24%) and the median University of California, Los Angeles (UCLA) score was 6.0 (IQR 5 to 8). Men had significantly better OHS (p = 0.02) and UCLA scores (p = 0.01) than women. The BHR provides excellent survival and functional results in men into the second decade, with good results achieved in appropriately selected women.

Mortality and implant revision rates of hip arthroplasty in patients with osteoarthritis: registry based cohort study.

OBJECTIVES: To examine mortality and revision rates among patients with osteoarthritis undergoing hip arthroplasty and to compare these rates between patients undergoing cemented or uncemented procedures and to compare outcomes between men undergoing stemmed total hip replacements and Birmingham hip resurfacing. DESIGN: Cohort study. SETTING: National Joint Registry. POPULATION: About 275,000 patient records. MAIN OUTCOME MEASURES: Hip arthroplasty procedures were linked to the time to any subsequent mortality or revision (implant failure). Flexible parametric survival analysis methods were used to analyse time to mortality and also time to revision. Comparisons between procedure groups were adjusted for age, sex, American Society of Anesthesiologists (ASA) grade, and complexity. RESULTS: As there were large baseline differences in the characteristics of patients receiving cemented, uncemented, or resurfacing procedures, unadjusted comparisons are inappropriate. Multivariable survival analyses identified a higher mortality rate for patients undergoing cemented compared with uncemented total hip replacement (adjusted hazard ratio 1.11, 95% confidence interval 1.07 to 1.16); conversely, there was a lower revision rate with cemented procedures (0.53, 0.50 to 0.57). These translate to small predicted differences in population averaged absolute survival probability at all time points. For example, compared with the uncemented group, at eight years after surgery the predicted probability of death in the cemented group was 0.013 higher (0.007 to 0.019) and the predicted probability of revision was 0.015 lower (0.012 to 0.017). In multivariable analyses restricted to men, there was a higher mortality rate in the cemented group and the uncemented group compared with the Birmingham hip resurfacing group. In terms of revision, the Birmingham hip resurfacings had a similar revision rate to uncemented total hip replacements. Both uncemented total hip replacements and Birmingham hip resurfacings had a higher revision rate than cemented total hip replacements. CONCLUSIONS: There is a small but significant increased risk of revision with uncemented rather than cemented total hip replacement, and a small but significant increased risk of death with cemented procedures. It is not known whether these are causal relations or caused by residual confounding. Compared with uncemented and cemented total hip replacements, Birmingham hip resurfacing has a significantly lower risk of death in men of all ages. Previously, only adjusted analyses of hip implant revision rates have been used to recommend and justify use of cheaper cemented total hip implants. Our investigations additionally consider mortality rates and suggest a potentially higher mortality rate with cemented total hip replacements, which merits further investigation.

Birmingham hip resurfacing: a minimum follow-up of ten years.

We report the survival, radiological and functional outcomes of a single surgeon series of his first 144 consecutive Birmingham hip resurfacing procedures (130 patients) at a minimum of ten years. There were ten revisions during this time. Although no patients were lost to follow-up some did not complete the scoring assessment or undergo radiological assessment at ten years. The ten-year survival for male patients was 98.0% (95% confidence interval 95.2 to 100). The ten-year survival for the total cohort with aseptic revision as the endpoint was 95.5% (95% confidence interval 91.8 to 99.0) and including revisions for sepsis was 93.5% (95% confidence interval 89.2 to 97.6). The median modified Oxford hip score at ten years was 4.2% (interquartile range 0 to 19) and the median University of California, Los Angeles score was 7.0 (interquartile range 5.0 to 8.0). This study confirms the midterm reports that metal-on-metal hip resurfacing using the Birmingham Hip provides a durable alternative to total hip replacement, particularly in younger male patients wishing to maintain a high level of function, with low risk of revision for at least ten years.

One- or two-stage bilateral metal-on-metal hip resurfacing arthroplasty.

Patients considered suitable for total hip resurfacing arthroplasty often have bilateral disease. The peri-operative complications, transfusion requirements, hospital stay, outcome and costs in patients undergoing one-stage bilateral total hip resurfacing were compared with a group of patients undergoing a two-stage procedure. A total of 92 patients were included in the study, of which 37 (40%) had a one-stage and 55 (60%) had a two-stage resurfacing. There were no significant differences in age, gender, or American Society of Anaesthesiologists grade between the groups (p = 0.31, p = 0.23, p = 0.13, respectively). There were three systemic complications in the one-stage group (8.1%) and one in the two-stage group (1.8% of patients; 0.9% of procedures). There was no significant difference in the complication rate (p = 0.72) or the transfusion requirements (p = 0.32) between the two groups. The one-stage group had a reduced total hospital stay of five days (95% confidence interval 4.0 to 6.9; p < 0.001), reduced length of time to completion of all surgery of five months (95% confidence interval 2.6 to 8.3; p < 0.001), and the reduced cost was 35% less than that of a two-stage procedure. However, the total anaesthetic time was significantly longer for the one-stage group (p < 0.001; 95% confidence interval 31 to 52). This study demonstrates that consideration should be given to one-stage surgery for patients with bilateral symptomatic disease suitable for metal-on-metal hip resurfacing. A one-stage procedure appears to have benefits for both the patient and the hospital without additional complications.

Birmingham hip resurfacing arthroplasty. A minimum follow-up of five years.

We report the survival at five years of 144 consecutive metal-on-metal resurfacings of the hip implanted between August 1997 and May 1998. Failure was defined as revision of either the acetabular or femoral component for any reason during the study period. The survival at the end of five years was 98% overall and 99% for aseptic revisions only. The mean age of the patients at implantation was 52.1 years. Three femoral components failed during the first two years, two were infected and one fractured. A single stage revision was carried out in each case. No other revisions were performed or are impending. No patients were lost to follow-up. Four died from unrelated causes during the study period. This study confirms that hip resurfacing using a metal-on-metal bearing of known provenance can provide a solution in the medium term for the younger more active adult who requires surgical intervention for hip disease.

Serological detection of Gram-positive bacterial infection around prostheses.

Coagulase-negative staphylococci produce an exocellular glycolipid antigen which has potential as a serological marker of infection in bone. The value of this newly detected antigen was investigated by enzyme-linked immunosorbent assay (ELISA) in 15 patients with culture-proven infection of prostheses caused by Gram-positive bacteria. The antigen was purified by gel-permeation chromatography from the culture supernatants of coagulase-negative staphylococci grown in a chemically defined medium. There were significant differences (p < 0.0001) between the serum IgG and IgM levels in patients with infection due to Gram-positive staphylococci and those of a control group of 32 patients with no infection. The ELISA test, which has potential for the diagnosis of infection, may be valuable in distinguishing between staphylococcal infection around prostheses and aseptic loosening.

Failure after customized curved femoral stems in total hip arthroplasty for Paget's disease.

We describe 2 patients with Paget's disease who underwent total hip arthroplasty for osteoarthrosis. In view of the femoral deformity in each case, a custom-made, long, curved femoral stem was used. Both patients have subsequently sustained periprosthetic fractures at the level of the tip of the prosthesis.

Articular interposition of broken trochanteric wires.

A case of recurrent dislocation of total hip arthroplasty with intra-articular migration of broken trochanteric wires and interposition between the articulating surfaces of the prosthetic components is reported. The patient was treated with revision total arthroplasty with good result. This unusual complication should always be considered when performing trochanteric osteotomy in total hip replacement.

Oxidative stress in cyclosporin and azathioprine treated renal transplant patients.

The major cause of death following transplantation is cardiovascular disease. Among the many processes involved in atherogenesis, oxidative stress and modification of low density lipoprotein has been assigned a major role. This in turn may be affected by the immunosuppressive regime used. We studied oxidative stress in 40 renal transplant patients receiving two different immunosuppressive regimens (20 on cyclosporin, 20 on azathioprine/prednisolone), and 19 normal controls. Changes in lipid peroxidation (assessed as thiobarbituric acid reacting substances, TBARS), antioxidant enzyme activities (glutathione reductase GSHPx, glutathione peroxidase GSHPx and superoxide dismutase SOD) vitamin E and antioxidant associated trace metals (selenium, copper, zinc) were studied. Alteration of erythrocyte membrane fluidity was examined using the fluorescent probe 1,6 diphenyl-1,3,5-hexatriene (DPH). Both transplant groups showed no difference in TBARS, lipid standardised vitamin E, copper or selenium compared to controls. Zinc was significantly increased in both the cyclosporin and azathioprine groups compared to controls (P < 0.05). SOD was reduced in both transplant groups compared to controls (P < 0.001). GSHPx was elevated in both groups compared to controls but only reached significance in the azathioprine treated group (P < 0.005). GSHRx was slightly elevated in both transplant groups but did not reach significance. Erythrocyte membrane anisotropy was decreased in the cyclosporin treated group (P < 0.05). There was no difference in the azathioprine group compared to controls. The present results suggest an adaptive response to increased oxidative stress in both transplant groups sufficient to minimise markers of oxidative stress (TBARS and anisotropy). The results also suggest no significant difference between the two immunosuppressive regimes with regard to oxidative stress.

Metal on metal surface replacement of the hip. Experience of the McMinn prothesis.

The historical failure of surface replacement has been due to the production of wear debris with subsequent bone resorption, loosening, and failure. To avoid these problems, a surface replacement using a metal on metal bearing allowing thin components and femoral design and instrumentation to avoid varus alignment has been designed. Two hundred thirty-five joints have been resurfaced with this prosthesis in almost 5 years. There have been no femoral neck fractures and no dislocations. There have been 4 designs differing in the method of fixation. In the press fit group, 6 of 70 hips had to be revised for aseptic loosening. In the cemented group, debonding of the cup occurred in 3 of 43 cases. Six patients had hydroxyapatite coated components and have had excellent clinical outcomes. The current design uses a peripherally expanded hydroxyapatite coated cup and a cemented metal head; 116 of this design have been implanted during a 19-month period with excellent outcome. Despite short followup the authors are hopeful that the combination of a polar metal on metal bearing with appropriate fixation will yield a method of preserving bone stock in the younger patient requiring arthroplasty.