Intertarsal and Tarsometatarsal Joints
The intertarsal joints include the three cuneonavicular joints, the intercuneiform joints, the cuboideonavicular joint, and the cuneocuboid joint. The tarsometatarsal (TMT) joint complex, known as the Lisfranc joints, is comprised of the five metatarsals, the three cuneiforms and the cuboid.
The base of the second metatarsal is recessed into the midfoot, and forms a key-like configuration with the intermediate cuneiform. The rigid second metatarsal (and also so some degree the third) provides a central rigid structure to the longitudinal arch, allowing a rigid lever for push-off in late stance.
The motion of the first, fourth, and fifth tarsometatarsal joints are much greater than the second metatarsal. The first tarsometatarsal joint has approximately 10° of plantar flexion during late stance. There is negligible motion in other plantes of motion for these joints. The intertarsal joints are closely congruent with minimal gliding motion between each other.
The Lisfranc ligament has an integral role in providing midfoot stability. It attaches from the medial cuneiform to the base of the 2nd metatarsal with its three segments. The TMJ joint complex is intrinsically stable because of the arch-like configuration which is best seen in cross-section.
Pronator and Supinator Forefoot Twist
The most medial and lateral tarsometatarsal joints are flexible and allow the forefoot to invert and evert independently of the hindfoot.
With the action of peroneus longus, and plantarflexion of the first MTPJ to 10°, a "pronator twist" of the forefoot is produced. The medial foot moves plantarward, and the entire surface of the foot faces more laterally. Likewise, when the ground reaction force of an uneven terrain pushes the medial forefoot is a dorsal direction, a "supinator twist" is produced.
The pronator and supinator twists allows accomodation to variable terrain and also provides sufficient push-off from the medial border of the foot.
- Basic Biomechanics of the Musculoskeletal System - Nordin 4th edition 2012
- ↑ Solan, M. C., Moorman, C. T., Miyamoto, R. G., Jasper, L. E. & Belkoff, S. M. Ligamentous restraints of the second tarsometatarsal joint: a biomechanical evaluation. Foot Ankle Int. 22, 637–641 (2001).