60 women with chronic anterior cruciate ligament (ACL) instability were randomized to determine the effect of an extra-articular procedure in addition to ACL reconstruction on knee stability following surgery. Patients were allocated to undergo reconstruction with or without extra-articular MacIntosh procedure modified by Cocker-Arnold, and were followed-up at a mean 44.6 months for knee stability, laxity, pain, activity and clinical IKDC outcomes. The results indicated that knee stability was significantly improved with the extra-articular procedure when examined by the pivot-shift test, but there were no significant difference between groups in Lachman test outcome.