The role of prophylactic antibiotics in spinal instrumentation. A rabbit model.

STUDY DESIGN: A rabbit model was used to test the efficacy of cefazolin administered in various therapeutic regimens in preventing iatrogenic Staphylococcus aureus infections during spinal instrumentation. OBJECTIVE: To assess the efficacy of various prophylactic therapeutic regimens of cefazolin in preventing iatrogenic S. aureus infections during spinal instrumentation. SUMMARY OF BACKGROUND DATA: Previous studies have not dealt specifically with the occurrence of iatrogenic S. aureus infections during spinal instrumentation in a prospective fashion. METHODS: Twenty New Zealand White rabbits underwent a posterior approach to the lumbar spine. Fifteen of the animals then had double-braided 26-gauge surgical wire placed around bilateral L3-L4 and L4-L5 facet joints. A standardized volume of a 103 S. aureus/mL of solution was then inoculated onto the fusion-hardware site in all rabbits. The rabbits were divided into four groups receiving various antibiotic dose regimens. Five days after surgery, the animals were killed, and cultures were obtained. RESULTS: All of the rabbits receiving no antibiotic had fusion sites infected with S. aureus. None of the animals who received prophylactic cefazolin produced cultures that grew S. aureus. A specimen from one fusion site cultured Staphylococcus epidermidis, which is not sensitive to cefazolin. Analysis of these data using Fisher's exact test resulted in a P value of 0.008 when results in antibiotic groups were compared with those in a group receiving no antibiotics and a P value of 0.0003 when all groups were compared. CONCLUSIONS: This model was valid and reproducible for the study of spinal instrumentation and infection. In addition, the data support the efficacy and use of prophylactic intravenous antibiotics in preventing infection in spinal instrumentation and fusion surgery.

Arthroscopic synovectomy for recurrent hemarthrosis of the ankle in hemophilia.

Nine patients with a history of recurrent hemarthroses of the ankle due to severe hemophilia were evaluated following arthroscopic ankle synovectomy. Follow-up averaged 33 months (range, 9 to 67 months) and included ankle range of motion, frequency of ankle hemarthroses, radiographic findings, and a functional assessment. The average age at the time of surgery was 12.3 years (range, 6.1 to 21.9 years). The average are of ankle motion was 48.4 degrees (range, 30 degrees to 70 degrees) postoperatively. The functional score as modified from Mazur averaged 36.1 points (range, 17 to 68 points) preoperatively, and 77.9 points (range, 32 to 100 points) postoperatively. Radiographic evidence of ankle arthropathy remained stable for most ankles. Arthroscopic ankle synovectomy for recurrent hemarthrosis due to hemophilia is a viable alternative to open ankle synovectomy for controlling the frequency of ankle bleeds and maintaining ankle function.