Biomechanics: Joint locks Leglocks

Biomechanics of the Toe Hold

A toe hold is a leg lock that attacks the ankle. The submission involves torque force combining plantarflexion and inversion motion to the ankle which often results in ligament sprain. With sufficient force ligament rupture and ankle dislocation can occur.

This leg lock primarily attacks two joints simultaneously that make up the ankle.
1. Talocrural joint
2. Subtalar joint

The talocrural joint allows the foot to lift up and push down (dorsiflexion and plantarflexion). This is the joint that is primarily targeted by an ankle lock. The subtalar joint allows the foot to fold in and out (inversion and eversion). The toe hold submission targets both joints (talocrural and subtalar) simultaneously by folding the foot down and in (Combining plantarflexion and inversion).

There are two ligaments that primarily prevent this movement:
1. Anterior talofibular ligament (ATFL)
2. Calcaneofibular ligament (CFL)
These are the same ligaments that are damaged from a typical rolled ankle (ankle sprain).

Other structures that prevent this movement.
1. Posterior talofibular ligament: This ligament assists with hind foot stability but damage to this ligament is rare.
2. Extensor and Fibular Retinacula: Connective tissue that reinforces the ankle joint capsule.

Typical presentation of a toe hold injury
The ATFL is generally the first ligament to fail, followed by the CFL. When both structures are ruptured there will be stress force on the retinaculum. When all these structures fail the talus may dislocate from the mortise. Generally medial dislocations will be accompanied by malleolar fracture (either medial or lateral).

Can toe holds also damage the knee?
The typical variation of a toe hold isolates the force to the ankle, however there are some variations that can damage the knee. Instead of inverting the ankle it is possible to internally rotate the tibia (shinbone), which creates similar torque to an outside heel hook.

Reference:
1. Martin, R. L., Davenport, T. E., Paulseth, S., Wukich, D. K., Godges, J. J., Altman, R. D., … & MacDermid, J. (2013). Ankle stability and movement coordination impairments: ankle ligament sprains: clinical practice guidelines linked to the international classification of functioning, disability and health from the orthopaedic section of the American Physical Therapy Association. Journal of Orthopaedic & Sports Physical Therapy, 43(9), A1-A40.
2. Neumann, D. A. Kinesiology of the Musculoskeletal System: Foundations for rehabilitation. 2010. Mosby Elsevier.

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