Relationships between tibial rotary torque and knee flexion/extension after tendon transplant surgery

The hamstring muscles play an important role in decelerating and checking tibial rotation before excessive stresses are applied to knee support structures. The purpose of this study was to determine the relationships between standard flexion/extension rehabilitative techniques and tibial rotary torque among subjects who had received pes anserinus transfers at least 1 year prior. Postsurgical and healthy contralateral limbs of 15 males were tested for maximum, isokinetic knee flexion/extension and internal/external tibial rotation. An adjustable chair and stabilizing boot were used to minimize extraneous hip, thigh and subtalar movements. Product-moment correlation coefficients were computed to determine the relationships between muscle forces generated during tibial rotation and knee flexion/extension. Relatively small relationships were found between rotation and flexion. Tibial rotation and flexion were more highly correlated in the nonsurgical than in the surgical limbs. The results also revealed that peak torque was generated within the first 5-10 degrees of motion for tibial rotation and within the first 20-30 degrees of motion for knee flexion and extension. The data indicate that measures of maximal knee flexor torque cannot be used to predict the rotational capabilities of the same muscle group and that separate measurement and rehabilitative techniques are necessary. Further analyses of postsurgical knees revealed force deficits among knee flexors and extensors when compared to nonsurgical counterparts. The findings suggest long-term sensitivity of the quadriceps to immobility.