The biological significance of cobalt-chromium wear particles from metal-on-metal hip replacements may be different to the effects of the constituent metal ions in solution. Bacteria may be able to discriminate between particulate and ionic forms of these metals because of a transmembrane nickel/cobalt-permease. It is not known whether wear particles are bacteriocidal.

We compared the doubling time of coagulase negative staphylococcus, Staphylococcus aureus and methicillin resistant S. aureus when cultured in either wear particles from a metal-on-metal hip simulator, wear particles from a metal-on-polyethylene hip simulator, metal ions in solution or a control.

Doubling time halved in metal-on-metal (p = 0.003) and metal-on-polyethylene (p = 0.131) particulate debris compared with the control.

Bacterial nickel/cobalt-transporters allow metal ions but not wear particles to cross bacterial membranes. This may be useful for testing the biological characteristics of different wear debris. This experiment also shows that metal-on-metal hip wear debris is not bacteriocidal.

The creep and wear behaviour of highly cross-linked polyethylene and standard polyethylene liners were examined in a prospective, double-blind randomised, controlled trial using radiostereometric analysis.

We randomised 54 patients to receive hip replacements with either highly cross-linked polyethylene or standard liners and determined the three-dimensional penetration of the liners over three years.

After three years the mean total penetration was 0.35 mm (SD 0.14) for the highly cross-linked polyethylene group and 0.45 mm (SD 0.19) for the standard group. The difference was statistically significant (p = 0.0184). From the pattern of penetration it was possible to discriminate creep from wear. Most (95%) of the creep occurred within six months of implantation and nearly all within the first year. There was no difference in the mean degree of creep between the two types of polyethylene (highly cross-linked polyethylene 0.26 mm, SD 0.17; standard 0.27 mm, SD 0.2; p = 0.83). There was, however, a significant difference (p = 0.012) in the mean wear rate (highly cross-linked polyethylene 0.03 mm/yr, SD 0.06; standard 0.07 mm/yr, SD 0.05). Creep and wear occurred in significantly different directions (p = 0.01); creep was predominantly proximal whereas wear was anterior, proximal and medial.

We conclude that penetration in the first six months is creep-dominated, but after one year virtually all penetration is due to wear. Highly cross-linked polyethylene has a 60% lower rate of wear than standard polyethylene and therefore will probably perform better in the long term.

Open surgery is rarely justified for the initial treatment of a unicameral bone cyst, but there is some debate concerning the relative effectiveness of closed methods. This study compared the results of steroid injection with those of autologous bone marrow grafting for the treatment of unicameral bone cysts. Between 1990 and 2001, 30 patients were treated by steroid injection and 28 by grafting with autologous bone marrow. The overall success rates were 86.7% and 92.0%, respectively (p > 0.05). The success rate after the initial procedure was 23.3% in the steroid group and 52.0% in those receiving autologous bone marrow (p < 0.05), and the respective cumulative success rates after second injections were 63.3% and 80.0% (p > 0.05). The mean number of procedures required was 2.19 (1 to 5) and 1.57 (1 to 3) (p < 0.05), the mean interval to healing was 12.5 months (4 to 32) and 14.3 months (7 to 36) (p > 0.05), and the rate of recurrence after the initial procedure was 41.7% and 13.3% in the steroid and in the autologous bone marrow groups, respectively (p < 0.05).

Although the overall rates of success of both methods were similar, the steroid group had higher recurrence after a single procedure and required more injections to achieve healing.

We have analysed the management and clinical outcome of a series of consecutive patients who had a total hip replacement and developed post-operative surgical site infection (SSI) with methicillin-resistant Staphylococcus aureus. The incidence of this infection was 1% over a period of five years. We studied SSI in 15 patients (16 infections) with a mean age of 72.7 years (53 to 81). In all, 12 of the infections occurred early and half of the infections involved the prosthesis, resulting in an increase of 11-fold in the cumulative hospital stay.

Methicillin-resistant Staph. aureus was successfully eradicated in all the patients after a mean follow-up of 53.6 months (25 to 88). Superficial incisional infections resolved after antibiotic therapy alone while deep infections required multiple operative debridements. Attempted retention of the implant in early organ space infections was successful in only one of five patients. Only three patients with implant-level infections obtained a pain-free, functional prosthesis while a further three required excision arthroplasty. We have formulated a protocol of treatment which may serve as a guide in the management of these infections.

We retrospectively identified 18 consecutive patients with synovial chrondromatosis of the shoulder who had arthroscopic treatment between 1989 and 2004. Of these, 15 were available for review at a mean follow-up of 5.3 years (2.3 to 16.5). There were seven patients with primary synovial chondromatosis, but for the remainder, the condition was a result of secondary causes. The mean Constant score showed that pain and activities of daily living were the most affected categories, being only 57% and 65% of the values of the normal side. Surgery resulted in a significant improvement in the mean Constant score in these domains from 8.9 (4 to 15) to 11.3 (2 to 15) and from 12.9 (5 to 20) to 18.7 (11 to 20), respectively (unpaired t-test, p = 0.04 and p < 0.0001, respectively). Movement and strength were not significantly affected. Osteoarthritis was present in eight patients at presentation and in 11 at the final review. Recurrence of the disease with new loose bodies occurred in two patients from the primary group at an interval of three and 12 years post-operatively. In nine patients, loose bodies were also present in the bicipital groove; seven of these underwent an open bicipital debridement and tenodesis.

We found that arthroscopic debridement of the glenohumeral joint and open debridement and tenodesis of the long head of biceps, when indicated, are safe and effective in relieving symptoms at medium-term review.

We have analysed from the Finnish Arthroplasty Register the long-term survivorship of the 12 most commonly-used cemented implants between 1980 and 2005 in patients aged 55 years or older with osteoarthritis.

Only two designs of femoral component, the Exeter Universal and the Müller Straight femoral component had a survivorship of over 95% at ten years with revision for aseptic loosening as the endpoint. At 15 years of the femoral and acetabular component combinations, only the Exeter Universal/Exeter All-poly implant had a survival rate of over 90% with revision for aseptic loosening as the endpoint. In the subgroup of patients aged between 55 and 64 years, survivorship overall was less than 90% at ten years.

The variation in the long-term rates of survival of different cemented hip implants was considerable in patients aged 55 years or older. In those aged between 55 and 64 years, none of the cemented prostheses studied yielded excellent long-term survival rates (≥ 90% at 15 years).

We assessed the outcome of patients with Vancouver type B2 and B3 periprosthetic fractures treated with femoral revision using an uncemented extensively porous-coated implant. A retrospective clinical and radiographic assessment of 22 patients with a mean follow-up of 33.7 months was performed. The mean time from the index procedure to fracture was 10.8 years. There were 17 patients with a satisfactory result. Complications in four patients included subsidence in two, deep sepsis in one, and delayed union in one. Concomitant acetabular revision was required in 19 patients. Uncemented extensively porous-coated femoral stems incorporate distally allowing stable fixation. We found good early survival rates and a low incidence of nonunion using this implant.

This study assessed the frequency of acute injury to the spinal cord in Irish Rugby over a period of ten years, between 1995 and 2004. There were 12 such injuries; 11 were cervical and one was thoracic. Ten occurred in adults and two in schoolboys. All were males playing Rugby Union and the mean age at injury was 21.6 years (16 to 36). The most common mechanism of injury was hyperflexion of the cervical spine and the players injured most frequently were playing at full back, hooker or on the wing. Most injuries were sustained during the tackle phase of play. Six players felt their injury was preventable. Eight are permanently disabled as a result of their injury.

Low back injuries account for the greatest loss of playing time for professional fast bowlers in cricket. Previous radiological studies have shown a high prevalence of degeneration of the lumbar discs and stress injuries of the pars interarticularis in elite junior fast bowlers. We have examined MRI appearance of the lumbar spines of 36 asymptomatic professional fast bowlers and 17 active control subjects. The fast bowlers had a relatively high prevalence of multi-level degeneration of the lumbar discs and a unique pattern of stress lesions of the pars interarticularis on the non-dominant side. The systems which have been used to classify the MR appearance of the lumbar discs and pars were found to be reliable. However, the relationship between the radiological findings, pain and dysfunction remains unclear.

We examined the effects of previous resection of the radial head and synovectomy on the outcome of subsequent total elbow arthroplasty in patients with rheumatoid arthritis.

Fifteen elbows with a history of resection and synovectomy were compared with a control group of patients who had elbow arthroplasty with an implant of the same design. The mean age in both groups was 63 years. In the study group, resection of the radial head and synovectomy had been undertaken at a mean of 8.9 years before arthroplasty. The mean radiological follow-up for the 13 available patients in the study group was 5.89 years (0.3 to 11.0) and in the control group was 6.6 years (2.2 to 12.6). There were no revisions in either group. The mean Mayo elbow performance score improved from 29 to 96 in the study group, with similar improvement in the control group (28 to 87). The study group had excellent results in 13 elbows and good results in two. The control group had excellent results in seven and good results in six.

Our experience indicates that previous resection of the radial head and synovectomy are not associated with an increased rate of revision following subsequent arthroplasty of the elbow. However, there was a higher rate of complication in the study group compared with the control group.