The measurement of anterior knee laxity after ACL reconstructive surgery.

An objective clinical instrument known as a knee ligament Arthrometer was developed. The instrumentation system was applied to measurements of knee ligament laxity in the operating room with the patients under anesthesia. Prereconstruction and immediate postreconstruction measurements were made with the patient still on the operating table. The change in laxity of the patient's operated knee as compared to the opposite nonoperated control knee was documented for 19 chronic and 24 acute patients. Four separate reconstruction types were studied in the operating room. The immediate postreconstruction measurements documented that all four of the reconstruction types were equally effective in the immediate restoration of normal laxity in the ACL-deficient knees. The Arthrometer proved to be a useful tool for confirming that each patient's normal knee laxity was reestablished in the O.R. by its reconstruction.