The hamstring has been implicated to have a mechanical effect on tibial torsion. The hamstring is really three muscles: semimembranosus, semitendinosus (medial hamstring) and biceps femoris (lateral hamstring). They all function to extend the hip and flex the knee. Semimembranosus and semitendinosus attach medially to the tibia, and the biceps femoris attach laterally to the fibula and lateral condyle of the tibia. They have different nerves that innervate them so they can be contracted in isolation. This means there can be differences in strength and tone medially versus laterally. Jonasson et al. (2016), determined that internal tibial torsion favors the medial hamstring while the lateral hamstring favors external tibial torsion. Additionally, they found that athletes that had an ACL reconstruction with a medial hamstring graft had selective weakness of the medial hamstring compared to the lateral hamstring. The lateral hamstring is also the most common lower leg injury and may be prone to scarring and post-injury restriction. Theoretically, if the lateral hamstring is tight, and the medial hamstring is weak, it could place an external torsion force on the tibia.

Some other muscles that may contribute to this position is a tight lateral gastrocnemius (calf) and a weak popliteus (muscle behind the knee). One of the functions of the popliteus is to medially rotate the tibia. If the lateral side of the leg is tensioned, and the medial side is not adequately strong enough, imbalances can occur which may contribute to malalignment.

What can be done about it?

If it is truly mechanical in nature, it may be managed with corrective exercises. Namely, elongating lateral hamstring and lateral gastroc with stretching and soft tissue mobilization, and strengthening medial hamstring and popliteus. Adjacent joints would have to be screened for any abnormalities in strength and range of motion, and addressed if indicated. Modifications may be warranted when it comes to stepping/squatting mechanics. This becomes complicated quickly and your best course of action is to see an orthopedic physical therapist. Surgery may be indicated for some. Those with recurrent dislocations and have external tibial torsion 30 degrees or above may be surgical candidates.

References:

Kim, H. Y., Kim, K. J., Yang, D. S., Jeung, S. W., Choi, H. G., & Choy, W. S. (2015). Screw-Home Movement of the Tibiofemoral Joint during Normal Gait: Three-Dimensional Analysis. Clinics in Orthopedic Surgery, 7(3), 303. doi:10.4055/cios.2015.7.3.303

Passmore, E., Graham, H. K., Pandy, M. G., & Sangeux, M. (2018). Hip- and patellofemoral-joint loading during gait are increased in children with idiopathic torsional deformities. Gait & Posture,63, 228-235. doi:10.1016/j.gaitpost.2018.05.003

Chassaing, V., Zeitoun, J., Camara, M., Blin, J., Marque, S., & Chancelier, M. (2017). Tibial tubercle torsion, a new factor of patellar instability. Orthopaedics & Traumatology: Surgery & Research,103(8), 1173-1178. doi:10.1016/j.otsr.2017.07.019

Cameron, J. C., & Saha, S. (1996). External Tibial Torsion. Clinical Orthopaedics and Related Research, 328, 177-184. doi:10.1097/00003086-199607000-00028

Gigante, A., Bevilacqua, C., Bonetti, M., & Greco, F. (2003). Increased external tibial torsion in Osgood-Schlatter disease. Acta Orthopaedica Scandinavica,74(4), 431-436. doi:10.1080/00016470310017749











