Does cyclical loading affect the elution of antibiotics from articulating cement knee spacers?

Two-stage revision surgery for infected total knee replacement offers the highest rate of success for the elimination of infection. The use of articulating antibiotic-laden cement spacers during the first stage to eradicate infection also allows protection of the soft tissues against excessive scarring and stiffness. We have investigated the effect of cyclical loading of cement spacers on the elution of antibiotics. Femoral and tibial spacers containing vancomycin at a constant concentration and tobramycin of varying concentrations were studied in vitro. The specimens were immersed and loaded cyclically to 250 N, with a flexion excursion of 45°, for 35 000 cycles. The buffered solution was sampled at set intervals and the antibiotic concentration was established so that the elution could be calculated. Unloaded samples were used as a control group for statistical comparison. The elution of tobramycin increased proportionately with its concentration in cement and was significantly higher at all sampling times from five minutes to 1680 minutes in loaded components compared with the control group (p = 0.021 and p = 0.003, respectively). A similar trend was observed with elution of vancomycin, but this failed to reach statistical significance at five, 1320 and 1560 minutes (p = 0.0508, p = 0.067 and p = 0.347, respectively). However, cyclically loaded and control components showed an increased elution of vancomycin with increasing tobramycin concentration in the specimens, despite all components having the same vancomycin concentration. The concentration of tobramycin influences both tobramycin and vancomycin elution from bone cement. Cyclical loading of the cement spacers enhanced the elution of vancomycin and tobramycin.

Early treatment with zoledronic acid prevents bone loss at the hip following acute spinal cord injury.

UNLABELLED: Osteoporosis after spinal cord injury is common. Reductions in bone density are rapid and fracture rates are higher after injury. Early treatment with 4 mg zoledronic acid significantly reduced bone loss at the hip compared to untreated individuals in the first year. Treatment appeared safe and well tolerated. INTRODUCTION: Bone mineral density (BMD) is lost rapidly following spinal cord injury (SCI), predominantly in the lower limbs. Bone turnover markers suggest an early increase in resorption. METHODS: A randomised, open-label study of 14 patients with acute SCI randomised to receive 4 mg IV zoledronic acid or standard treatment. BMD was measured by dual-X-ray absorptiometry at the lumbar spine and hip (femoral neck, total and trochanter) at baseline, 3, 6 and 12 months. Bone turnover markers (serum C-terminal telopeptide and Procollagen I N-terminal peptide and urinary N-terminal telopeptide/Cr ratio) were also measured. RESULTS: After 12 months, there was a significant difference in BMD between the groups at the total hip (12.4%, p = 0.005), trochanter (13.4%, p = 0.028) and lumbar spine (2.7%, p = 0.033). However, the difference between groups at the femoral neck was not significant (4.8%, p = 0.741). In the treated group, bone resorption was reduced and remained reduced up to 12 months. Other than flu-like symptoms immediately after the infusion, no adverse events were observed. CONCLUSION: IV zoledronic acid is an effective and well-tolerated treatment to prevent bone mineral density loss at the total hip and trochanter for up to 12 months following SCI.

Total hip arthroplasty does not aid weight loss.

INTRODUCTION: Increased body mass index (BMI) is associated with the development of osteoarthritis of the hip. Many overweight patients with an arthritic hip cite restricted mobility and pain as impeding factors in their attempts to lose weight. There is an assumption that weight loss will occur after their surgery due to increased mobility. PATIENTS AND METHODS: The records of 180 patients who had undergone total hip arthroplasty (THA) were reviewed to identify BMI prior to, and 2 years after, surgery. RESULTS: BMI significantly increased postoperatively, both in patients with a pre-operative BMI in the recommended range (P < 0.001) and in those whose pre-operative BMI was indicative of obesity (P = 0.01). CONCLUSIONS: Irrespective of pre-operative BMI, reduction in body mass index did not occur following hip replacement surgery.

A benign psoas mass following metal-on-metal resurfacing of the hip.

As metal-on-metal arthroplasty becomes more widespread, concerns are being raised about the potential dangers of metal particulate debris. We present the case of a benign psoas mass secondary to the presence of such particles. The mass was excised and the hip resurfacing subsequently revised to a total hip replacement.

Cold injury amputees--a psychosocial problem?

The rehabilitation of 8 cold injury lower limb amputees is described, 7 of whom were alcoholic and had significant personality disorders. Delayed wound healing was the only common physical problem but the psychosocial difficulties were substantial and were the principal determinant of outcome following rehabilitation.