Comparison of synovial fluid, urine, and serum ion levels in metal-on-metal total hip arthroplasty at a minimum follow-up of 18 years.

Diagnosis of adverse reactions to metal debris in metal-on-metal hip arthroplasty is a multifactorial process. Systemic ion levels are just one factor in the evaluation and should not be relied upon solely to determine the need for revision surgery. Furthermore, the correlation between cobalt or chromium serum, urine, or synovial fluid levels and adverse local tissue reactions is still incompletely understood. The hypothesis was that elevated serum and urine metal-ion concentrations are associated with elevated local metal-ion concentrations in primary total hip arthroplasties (THA) and with failure of metal-on-metal articulations in the long-term. In our present study, we evaluated these concentrations in 105 cementless THA with metal-on-metal articulating surfaces with small head diameter at a minimum of 18 years postoperatively. Spearman correlation showed a high correlation between the joint fluid aspirate concentration of cobalt and chromium with the serum cobalt (r = 0.81) and chromium level (r = 0.77) in patients with the THA as the only source of metal-ions. In these patients serum metal-ion analysis is a valuable method for screening. In patients with more than one source of metal or renal insufficiency additional investigations, like joint aspirations are an important tool for evaluation of wear and adverse tissue reactions in metal-on-metal THA.

Contamination of surfaces for osseointegration of cementless total hip implants by small aluminium oxide particles: analysis of established implants by use of a new technique.

BACKGROUND: The failure of total hip replacements because of wear, particle-induced osteolysis, and aseptic loosening has focussed interest on factors potentially affecting the rate of wear. In this context the effect of particle release from the bone-implant interface of cementless implants is poorly understood. The surface structure for bony ongrowth of many cementless implants is created by grit-blasting. Remnants from this process (Al2O3 particles) on these surfaces have been reported; these remnants have the potential to cause third-body wear. METHODS: We report a novel technique for isolation and quantification of alumina particle contamination. Stems from different manufacturers were electrochemically activated and etched to isolate the alumina residues. After filtration the particles were characterised by scanning electron microscopy and energy-dispersive X-ray analysis. RESULTS: Many Al2O3 particles were found on all the implants tested. A mean of 426,814 particles per mm(2) was measured. Particle size distribution ranged from 0.125 to 66.304 µm with a peak in the range 0.25-1 µm. CONCLUSIONS: Our main finding was a large amount of small Al2O3 particles on all blasted surfaces. On the basis of our results these alumina particle remnants cannot be excluded as a factor causing increased third-body wear.

Cementless total hip arthroplasty with the rectangular titanium Zweymüller stem: a concise follow-up, at a minimum of twenty years, of previous reports.

In 2002 and 2006, we reported the long-term results of 208 total hip replacements performed with the Zweymüller stem and a threaded cup in 200 patients. The present study gives an update on this patient cohort. At a minimum of twenty years postoperatively, seventy-three patients (seventy-five hips) were available for follow-up; twelve patients were lost to follow-up. The key findings of our previous reports were the absence of aseptic femoral stem loosening and a poor rate of survival of the threaded cup. Since then, two revisions have been performed because of aseptic stem loosening. We observed osteolytic lesions around the proximal part of the femoral component on twenty-four (47%) of fifty-one radiographs, but no stem was deemed at risk for loosening. The probability of survival of the stem at twenty years was 0.96 (95% confidence interval, 0.91 to 0.99), and the probability of survival of the cup at twenty years was 0.67 (95% confidence interval, 0.57 to 0.75). The Zweymüller femoral stem, a tapered, rectangular implant, continues to give excellent long-term results.

The posteromedial neurovascular bundle of the ankle: an anatomic study using plastinated cross sections.

PURPOSE: The aim of this study was to evaluate the topography of the posteromedial neurovascular bundle of the ankle. The anatomic relation of the posteromedial neurovascular bundle at different levels of the ankle was studied as an aid in planning minimally invasive surgery. A thorough knowledge of the local anatomy is a prerequisite before attempting release of the tibial nerve or when using the posteromedial portal for ankle arthroscopy. METHODS: A slice anatomy study was performed on 12 intact right male cadaveric lower limbs. The distal third of each limb was cut and the foot positioned in the neutral position. The measurements were performed at the level of the tibiotalar joint, at the tip of the medial malleolus, and at the sustentaculum tali. RESULTS: The tibial nerve is predicted to be 11.8 +/- 2.4 mm and the posterior tibial artery 16.7 +/- 3.8 mm anterior from the calcaneal tendon at the level of the tibiotalar joint. At the tip of the malleolus medialis, the tibial nerve is 14.3 +/- 2.5 mm and the posterior tibial artery 22.1 +/- 4.1 mm anterior to the Achilles tendon. The medial plantar nerve is situated at the sustentaculum tali level 8.4 +/- 3.4 mm and the lateral plantar nerve 16.1 +/- 3.1 mm posterior to the sustentaculum. CONCLUSIONS: On the basis of our anatomic data, a posteromedial portal made at the level of the tip of the medial malleolus seems to be safe, effective, and reproducible. Therefore a portal at this level would be advantageous for an endoscopic tarsal tunnel release or when using the posteromedial portal for ankle arthroscopy. Anatomic characteristics should be kept in mind when ankle surgery is performed, thereby reducing the risk of injury to the medial neurovascular bundle and offering easy access inside the posterior compartment of the ankle. CLINICAL RELEVANCE: This cadaveric study suggests that, by placing the posteromedial ankle portal at the tip of the medial malleolus, the risk of neurovascular injuries could be reduced.

Metal-on-metal hip implants: do they impair renal function in the long-term? A 10-year follow-up study.

INTRODUCTION: The aim of our study was to investigate a potential influence of elevated serumcobalt and serumchromiumlevels on renal function at minimum 10 years after implantation of a metal-on-metal hip. MATERIALS AND METHODS: Between November 1992 and June 1994 98 patients (44 m, 54 f) with an average age of 56 (22-79) years received a metal-on-metal bearing Metasul. At the time of the 10-year follow-up, 15 patients had died and 8 were lost to follow-up. The remaining 75 patients had laboratory analysis including serumcreatinine and full blood cell count as well as chromium and cobalt serum levels. RESULTS: Ten years postoperatively the median serumcreatinine level was 0.86 (0.55-1.51) mg/dl, the serumcreatinine clearance Ccr was in the normal range. The hemogram did not differ from that measured at the time of surgery. The median serumcobalt concentration was 0.75 (0.3-50.10) microg/l and the serumchromium concentration was 0.95 (0.3-58.6) mug/l, 10 years postoperatively. CONCLUSION: Our long-term data do not show any influence of serum cobalt or chromium concentrations on renal function following total hip arthroplasty.

Long-term follow-up of metal-on-metal total hip replacement.

Metal-on-metal articulations were reintroduced to reduce polyethylene particle-induced osteolysis. Elevated serum metal levels have been detected at short- and intermediate-term follow-up. There is little knowledge about long-term effects of increased ionic metal generation. Our study was undertaken to provide information about long-term survival, clinical outcome, radiographic appearance, and serum metal concentrations after a minimum 10 years follow-up with a metal-on-metal hip prosthesis: 105 cementless primary total hip prostheses with metal-on-metal articulating surfaces were implanted in 98 patients with a mean age of 56 years. Clinical data, radiographs, and blood samples were obtained at a follow-up visit 10 years after implantation. Serum cobalt and chromium levels were determined with use of atomic absorption spectrometry. General laboratory analyses included a full blood count and kidney function parameters. The Harris score was 92 points and the UCLA score 6 points after 10 years. Small osteolytic lesions and radiolucent lines were found in Gruen's zones 1, 7, 8, and 14. The probability of survival was 98.6%. The median serum cobalt concentration of the 22 patients with their hip replacement as the only source of cobalt was 0.75 microg/L (range, 0.3-50.1 microg/L). No patient was diagnosed with renal insufficiency during the study period. Five patients were diagnosed with a malignancy between surgery and the follow-up. We do not have evidence of an increased rate of primary malignancies nor could we detect renal failure in our study group. Serum metal levels did not differ from short- and intermediate term follow-up values.

Characterization, quantification, and isolation of aluminum oxide particles on grit blasted titanium aluminum alloy hip implants.

BACKGROUND: This study was undertaken to verify whether or not the microstructure of aluminum alloy implants interferes with the characterization and quantification of aluminum inclusions on their surfaces, resulting from grit blasting. METHODS: Four factory-fresh prostheses were investigated by scanning electron microscopy and X-ray microanalysis. Specimens were cut out of the stems and the cross-sections analyzed. The specimens were etched in hot 25% hydrochloric acid. The hydrochloric acid was subsequently filtered with a 0.2-microm-pore filter. The filters were scanned using electron microscopy and X-ray microanalysis. RESULTS: Aluminum oxide particles were found on all investigated stems; the diameter of the particles ranged from 4 to 100 microm. One hundred fifty-four particles were counted per mm(2). No particles were seen on the cross-sections of the implants. Scanning electron microscopy of the Millipore filters revealed aluminum oxide particles. CONCLUSION: Remnants of grit blasting were found only on the surfaces; none were observed on cross-sections. We conclude that the microstructure of titanium aluminum alloy does not interfere with the identification and quantification of particles. Particles were identified on the filters by electron microscopy and X-ray microanalysis. Aluminum oxide on the surface of grit-blasted titanium aluminum alloy implants is, in fact, a residue of grit blasting.

Cementless total hip arthroplasty with the rectangular titanium Zweymuller stem. A concise follow-up, at a minimum of fifteen years, of a previous report.

Between October 1986 and November 1987, 208 total hip arthroplasties were performed with use of the cementless Zweymüller stem and a threaded cup in 200 consecutive patients. Of 102 patients (108 hips) who were available for follow-up at a minimum of 180 months postoperatively, eighty-three (eighty-nine hips) had the primary joint replacement still intact. No stem had been revised because of aseptic loosening, but we found various degrees of osteolysis around sixteen (18%) of the implants. The probability of survival of the stem at fifteen years was 0.98 (95% confidence interval, 0.96 to 1.00). The probability of survival of the cup was 0.85 (95% confidence interval, 0.79 to 0.91).

Cup inclination and serum concentration of cobalt and chromium after metal-on-metal total hip arthroplasty.

We investigated whether cup inclination influences serum levels of cobalt and chromium after metal-on-metal total hip arthroplasty. Out of a consecutive series, 3 groups of 20 patients each were established according to their cup inclination: greatest inclination (55 degrees -63 degrees, mean 58 degrees), intermediate inclination (44 degrees -46 degrees, mean 45 degrees), and smallest inclination (23 degrees -37 degrees, mean 33 degrees). We did not detect any statistically significant difference of serum cobalt (P = .23) or serum chromium (P = .13) levels between the 3 groups applying the Kruskal Wallis test. However, 3 patients with cup inclinations of 58 degrees , 63 degrees , and 61 degrees exhibited 9.8-53.6-fold elevated cobalt and 9.5-30.5-fold elevated chromium levels when compared with the median concentrations of this trial. We therefore recommend accurate cup placement also for metal-on-metal articulations.

Cementless total hip arthroplasty with a tapered, rectangular titanium stem and a threaded cup: a minimum ten-year follow-up.

BACKGROUND: We report the results of cementless total hip arthroplasty with a tapered, rectangular titanium stem that was introduced in 1979 and continues to be used today with only minor changes. The aim of the design is to achieve primary stability to resist rotational and axial forces through precision rasping and press-fit implantation of a tapered, rectangular femoral component. METHODS: Between October 1986 and November 1987, 208 total hip arthroplasties with insertion of a tapered, rectangular titanium stem and a threaded cup without cement were performed in 200 consecutive patients (average age, sixty-one years; range, twenty-two to eighty-four years). RESULTS: At the time of the latest follow-up, fifty-one patients (fifty-two hips) had died and sixteen patients had been lost to follow-up, leaving 133 patients. Twelve hips had been revised, two in patients who subsequently died, leaving 123 living patients without revision. The median follow-up time was 120.7 months. Five cups needed revision surgery because of aseptic loosening; two, because of massive polyethylene wear; one, because of posttraumatic migration; and one, because of breakage. Three femoral stems were revised: one because of malpositioning (the reoperation was done five days after implantation); one, because of infection; and the third, after multiple failed acetabular revisions. The mean Harris hip score for the patients who did not have revision was 85.4 points (range, 46 to 100 points) at the time of the latest follow-up. Four patients (3%) complained of thigh pain that was not associated with another disorder. According to the criteria of Engh et al., all femoral implants were graded as stable bone-ingrown. The probability of survival of both the femoral and the acetabular component at ten years, with any revision as the end point, was 0.92 (95% confidence interval, 0.88 to 0.97). The probability of survival of the cup was 0.93 (95% confidence interval, 0.89 to 0.97), and that of the stem was 0.99 (95% confidence interval, 0.97 to 1.00). CONCLUSIONS: The results of arthroplasty with a tapered, rectangular titanium stem combined with a conical threaded cup inserted without cement were excellent at a minimum of ten years. Our data suggest that femoral stem fixation continues to be secure, while the threaded cup is prone to aseptic loosening.