Heterotopic ossification following joint replacement in the lower limb occurs in 3% to 90% of cases. Higher grades of heterotopic ossification can result in significant limitation of function and can negate the benefits of joint replacement. The understanding of the pathophysiology of this condition has improved in recent years. It would appear to be related to a combination of systemic and local factors, including over-expression of bone morphogenetic protein-4. There is currently little evidence to support the routine use of prophylaxis for heterotopic ossification in arthroplasty patients, but prophylaxis is recommended by some for high-risk patients. Radiotherapy given as one dose of 7 Gy to 8 Gy, either pre-operatively (< four hours before) or post-operatively (within 72 hours of surgery), appears to be more effective than indometacin therapy (75 mg daily for six weeks). In cases of prophylaxis against recurrent heterotopic ossification following excision, recent work has suggested that a combination of radiotherapy and indometacin is effective. Advances in our understanding of this condition may permit the development of newer, safer treatment modalities.

All surgical operations have the potential for contamination, and the equipment used can harbour bacteria. We collected samples from 100 elective primary hip and knee arthroplasties. These showed rates of contamination of 11.4% for the sucker tips, 14.5% for light handles, 9.4% for skin blades and 3.2% for the inside blades used during surgery; 28.7% of gloves used for preparation were also contaminated. Of the samples taken from the collection bags used during hip arthroplasty, 20% grew bacteria, which represents a significant microbial reservoir. Also, 17% of theatre gowns were contaminated at the end of the operation. Contamination was found in 10% of the needles used during closure of the fascia. Overall, 76% of the organisms grown were coagulase-negative staphylococcus. A total of 63% of operations showed contamination in the field of operation. Some changes in practice are suggested. Follow-up for a minimum of two years revealed one deep infection but the organism was not identified as a contaminant. These data provide a baseline for studying the bacteriology of the surgery of revision arthroplasty.