Wear debris was extracted from 21 worn hip and knee replacements. Its mutagenic effects were tested on human cells in tissue culture using the micronucleus assay and fluorescent in situ hybridisation.

The extracted wear debris increased the level of micronuclei in a linear dose-dependent manner but with a tenfold difference between samples. The concentration of titanium +/− vanadium and aluminium within the wear debris was linearly related both to the level of centromere-positive micronuclei in tissue culture, indicating an aneuploid event, and to the level of aneuploidy in vivo in peripheral blood lymphocytes. The concentration of cobalt and chromium +/− nickel and molybdenum in the wear debris correlated with the total index of micronuclei in tissue culture, both centromere-positive and centromere-negative i.e. both chromosomal breakage and aneuploidy events.

The results show that wear debris can damage chromosomes in a dose-dependent manner which is specific to the type of metal. The results from studies in vitro correlate with those in vivo and suggest that the wear debris from a worn implant is at least partly responsible for the chromosomal damage which is seen in vivo.

Aims: Limb sparing surgery, for selected cases of long bone primary malignancy, may be accomplished with the use of large prostheses. Conventional joint implants are known to release metal ions by corrosion or wear. The aim of this study was to determine if a specialist group of patients had elevated serum metal levels. Methods: Over a 12 month period, 20 patients who had undergone previous surgery were recruited from a bone tumour clinic. A 10ml venous blood sample was obtained and analysed for trace metals using a previously published mass-spectrometry technique. Results: Eight children (mean age 14.5 years) and 12 adults (mean age 46.5 years) were recruited a mean of 54 months and 86 months following surgery, respectively. Trace metal (aluminium, titanium, cobalt) elevation was observed in 5/8 (63%) paediatric cases and 6/12 (50%) adult cases. Three of the adults had signiþcantly raised levels, (≤ 50 times), and had undergone revision surgery for loosening. There was no observed implant loosening in the paediatric group. Conclusions: This small sample has demonstrated that many patients with long-term large tumour implants have trace metal levels below laboratory detection. Signiþcant elevation of metal levels in adults was associated with loosening or wear of implants. A signiþcant proportion of paediatric cases had slight elevations, but the signiþcance of this is unknown at present.

This prospective study evaluates the outcome of a new metal -on-metal total hip replacement in a younger group of patients.

Fifty-five primary all-metal total hip replacements (THR) were evaluated prospectively at a follow-up of 2.8–5.5 years. Patients were selected according to age and activity levels. The mean age was 58 years (41–69). 33 males and 22 females were included in the study. Surgery was carried out for osteoarthritis in 52 patients and for non-union fractured femoral neck, ankylosing spondilitis and post slipped upper femoral epiphysis in the three remaining patients. A single surgeon (the senior author) through the posterior approach carried out the surgery. All patients received the porous coated titanium shell with a Morse taper cobalt chrome liner and double wedge tapered polished cobalt chrome stem and modular head. Blood metal ion analysis was performed on a cohort of 24 patients using High Resolution Inductively Coupled Plasma Mass Spectrometry, sampling taken preoperatively and then repeated post operatively at 6 months, 1 year and then annually.

Clinical results have been excellent. X rays show Harris A cementation in all femurs, with no component migration or radiolucencies being identified on follow-up radiographs. No prosthesis to-date has required revision. One patient has died and one is lost to follow up. The following non-device related complications were reported in the group, 2 (4%) superficial wound infections, 1 (2%) dislocation, 1 (2%) thrombosis, 1 (2%) IT band defect and 2 (4%) impingement. The dislocation was treated with a closed reduction. The impingement has resolved by one year in both patients. The results of the pre and postoperative blood metal ion analysis demonstrate some elevated levels, these levels being similar to those previously reported in the literature.

The hybrid all-metal THR may represent a valuable alternative in the younger, high demand patient.