Between 2002 and 2008, 130 consecutive ankles were replaced with an hydroxyapatite (HA) and titanium-HA-coated Ankle Evolutive System total ankle prosthesis. Plain radiographs were analysed by two independent observers. Osteolytic lesions were classified by their size and location, with cavities > 10 mm in diameter considered to be ‘marked’. CT scanning was undertaken in all patients with marked osteolysis seen on the plain radiographs.

Osteolytic lesions were seen on the plain films in 48 (37%) and marked lesions in 27 (21%) ankles. The risk for osteolysis was found to be 3.1 (95% confidence interval 1.6 to 5.9) times higher with implants with Ti-HA porous coating.

Care should be taken with ankle arthroplasty until more is known about the reasons for these severe osteolyses.

Wear of polyethylene is associated with aseptic loosening of orthopaedic implants and has been observed in hip and knee prostheses and anatomical implants for the shoulder. The reversed shoulder prostheses have not been assessed as yet. We investigated the volumetric polyethylene wear of the reversed and anatomical Aequalis shoulder prostheses using a mathematical musculoskeletal model. Movement and joint stability were achieved by EMG-controlled activation of the muscles. A non-constant wear factor was considered. Simulated activities of daily living were estimated from in vivo recorded data.

After one year of use, the volumetric wear was 8.4 mm³ for the anatomical prosthesis, but 44.6 mm³ for the reversed version. For the anatomical prosthesis the predictions for contact pressure and wear were consistent with biomechanical and clinical data. The abrasive wear of the polyethylene in reversed prostheses should not be underestimated, and further analysis, both experimental and clinical, is required.

There are few reports in the literature of the diagnosis and treatment of the infected shoulder arthroplasty. Most deal with resection arthroplasty and two-stage exchange surgery. We present our results of one-stage exchange operation as treatment for the infected shoulder arthroplasty.

Our group comprised 16 patients (ten men, six women) with 16 infected arthroplasties. By the time of follow-up, two patients had died (mean 5.8 years), two could not be located and three had already undergone revision surgery. Nine patients were thus available for clinical examination and assessment.

The infections were largely caused by staphylococci, Propionibacterium species and streptococci. Two were early infections (within three months of surgery) and 14 were late infections. The mean follow-up was 5.8 years (13 months to 13.25 years) when the mean Constant-Murley score was 33.6 points and the mean University College of Los Angeles score 18.3 points.

Further revision was performed in three patients. One sustained a peri-prosthetic humeral fracture, another developed an acromial pseudarthrosis after transacromial surgery and the third suffered recurrent dislocations. No patient had a recurrence of infection.

A one-stage exchange procedure using antibiotic-loaded bone cement eradicated infection in all our patients and we suggest that such a procedure is at least as successful as either a resection arthroplasty or a two-stage exchange in the management of the infected shoulder arthroplasty.

Iontophoresis is a novel technique which may be used to facilitate the movement of antibiotics into the substance of bone using an electrical potential applied externally. We have examined the rate of early infection in allografts following application of this technique in clinical practice. A total of 31 patients undergoing revision arthroplasty or surgery for limb salvage received 34 iontophoresed sequential allografts, of which 26 survived for a minimum of two years. The mean serum antibiotic levels after operation were low (gentamicin 0.37 mg/l (0.2 to 0.5); flucloxacillin 1 mg/l (0 to 1) and the levels in the drains were high (gentamicin 40 mg/l (2.5 to 131); flucloxacillin 17 mg/l (1 to 43). There were no early deep infections. Two late infections were presumed to be haemotogenous; 28 of the 34 allografts were retained. In 12 patients with pre-existing proven infection further infection has not occurred at a mean follow-up of 51 months (24 to 82).