Study design with internal fixation and spontaneous recovery durations and sample size per group. Angle of extension in rat knee joints for the 24 groups at torque = 12.5 N-cm. *P ≤ 0.05 for difference between the mean ranges of knee extension of contracture versus contralateral knees. All P > .001 identified. #P ≤ 0.05 for gain in knee extension angle after recovery duration half, equal to, double, or quadruple the duration of surgical fixation compared to the previous duration. Error bars = 1 standard error of the mean.