Incidence of positive intraoperative allograft cultures used in knee ligament reconstruction.

Soft-tissue allografts are valuable options in knee ligament reconstructive surgery. The purpose of this study was to determine the risk of soft-tissue contamination before implantation and the occurrence of infection after implantation in patients who received soft-tissue allografts for knee reconstructive procedures. A retrospective review of medical records was performed for patients who had undergone knee ligament surgery with allograft tissues at one institution between 1993 and 2004. Cultures were positive in 6 (5.7%) of 105 cases. Coagulase-negative Staphylococcus was the most common organism. None of these patients developed postoperative infections. The culture-positive group had a longer period of joint effusion postoperatively, compared with the culture-negative group (14.2 weeks versus 9.6 weeks). Patients with positive cultures required no additional treatment other than close observation.

Antibacterial properties of synovial fluid in the knee.

This study evaluated antimicrobial properties of synovial fluid against 3 gram-positive organisms: Staphylococcus aureus, Streptococcus pyogenes, and Staphylococcus epidermidis. Synovial fluid was collected from the knees of 52 patients. Three gram-positive bacteria culture lines were incubated in wells containing either synovial fluid and broth, or broth alone. Fluid was plated and incubated, and colonies were counted after 1, 4, and 24 hours to determine bacterial growth. Statistically significant differences in bacterial counts were found between control and experimental groups at 0, 4, and 24 hours for all 3 bacterial species. Bacterial counts in the control specimens demonstrated exponential growth over 24 hours as would be expected in the absence of growth inhibition. In contrast, bacterial counts in all of the synovial fluid specimens decreased steadily over 24 hours. These results demonstrate synovial fluid possesses potent bactericidal activity against the most common gram-positive pathogens responsible for septic arthritis. Delineating these antimicrobial properties further may offer avenues to augment the body's protection against bacterial infections.

Safe zone for the placement of medial malleolar screws.

BACKGROUND: Hardware placement for fracture fixation can put soft-tissue structures at risk for injury or abutment. The prominence of the hardware is a frequent cause of pain after the fixation of ankle fractures. This study was designed to assess the risk of injury or abutment of the posterior tibial tendon with the placement of medial malleolar screws. METHODS: Ten unmatched cadaveric limbs that had been disarticulated at the knee were used, and the medial malleolus was exposed by dissection of the skin. With use of fluoroscopy and direct visualization of the deep fascia, three Kirschner wires were placed through the tip of the medial malleolus and directed parallel to the medial articular surface. The first wire was placed in the center of the anterior colliculus. Two additional wires were placed parallel and posterior to the initial wire at 5-mm intervals. The wires were overdrilled, and 4.0-mm screws were inserted over the Kirschner wires. The specimens were dissected to inspect for trauma and the proximity of the screws to the posterior tibial tendon. The medial malleolus was divided into three zones on the basis of anatomic landmarks. Zone 1 is the anterior colliculus; Zone 2, the intercollicular groove; and Zone 3, the posterior colliculus. RESULTS: Screws placed in Zone 1 (the anterior colliculus) did not contact the posterior tibial tendon in any specimens. Screws placed in Zone 2 (the intercollicular groove) were, on the average, 2 mm from the posterior tibial tendon. Screws placed in Zone 3 (the posterior colliculus) resulted in tendon abutment in all ten specimens and in tendon injury in five of the ten specimens. CONCLUSIONS: Screws inserted posterior to the anterior colliculus place the posterior tibial tendon at significant risk for injury or abutment.