Infection rates after 3175 total hip and total knee replacements performed with and without a horizontal unidirectional filtered air-flow system.

To determine the effect of the ventilation system on infection rates after total hip and total knee arthroplasties performed in operating rooms with and without a horizontal unidirectional filtered air-flow system, using modern antiseptic conditions and antibiotic prophylaxis, all of the single-stage procedures (3175 of a total of 4769) were subjected to statistical analysis and fifty-seven matched pairs for controls were established. A reduced infection rate after total hip replacement (from 1.4 to 0.9 per cent) and an increased infection rate after total knee replacement (from 1.4 to 3.9 per cent) were found when patients operated on in the filtered laminar air-flow operating room were compared with those whose operations were done in two conventional rooms. This pattern was statistically significant and was believed to be due to the positions of the operating team and of the wound with respect to the air flow. Prospectively accumulated factors (such as the experience of the surgeon, the duration of surgery, the diagnosis, and the patient's age) as well as retrospectively accumulated factors (such as predisposing conditions of the patient) did not explain the observed patterns of infection.

Joint looseness: a function of the person and the joint.

In order to evaluate whether joint-looseness is a function of a particular joint and/or a characteristic of the person (a trait), 124 male and female subjects varying in age from 6 to 18 were tested. Evidence was found that joint-looseness is a trait. The validity of the trait measure was enhanced by finding significant negative correlations with age and performance. Although females were significantly looser on some joint-looseness tests, they were not looser on the trait indicator.