Orthopedics - Oleksa A.P. 2006

Congenital and Acquired Deformities of the Lower Extremity
Orthopedic Deformities of the Foot

Anatomically, the FOOT consists of twenty-six bones that form an exquisite architectonic Structure capable of withstanding heavy loads while maintaining flexibility. A range of motion sufficient for proper function occurs in the interphalangeal, metatarsophalangeal, subtalar, and talonavicular joints, as well as at the Base of the first metatarsal bone. In the remaining joints, movement is extremely limited due to the tight interlocking of the bones. The Stability of the foot bones is ensured by the Muscles, a robust interosseous ligamentous apparatus, and the fibrous joint capsules.

The entire static posture of the lower extremities depends on the static endurance of the feet, which serve as the body's base of support during walking. Foot support is distributed across three points: the HEAD of the first metatarsal, the heads of the fourth and fifth metatarsals, and the calcaneal tuberosity. When walking on a slippery surface, the support area of the foot expands through the flexion of the toes, resting on their pads. Movement in the ankle and subtalar joints allows for supination and pronation of the foot, enabling it to adapt to uneven terrain. If motion in these joints is restricted, a person experiences pain when walking on uneven surfaces.

The foot features three arches: the lateral longitudinal arch, the medial longitudinal arch, and the anterior arch located between the heads of the first and the fourth-fifth Metatarsal Bones, sometimes referred to as the transverse arch.

The most pronounced is the medial longitudinal arch, formed by the calcaneus, the neck of the talus, the navicular bone, the first cuneiform, and the first metatarsal bone. All of these joints, with the exception of the cuneonavicular joint, possess a degree of mobility; therefore, the height of the medial arch is variable and depends primarily on Muscle Function and strength, as well as the condition of the ligamentous-capsular apparatus of the joints.

The lateral (outer) arch, formed by the calcaneus, the cuboid, and the fourth and fifth metatarsals, is maintained mainly by the ligamentous-capsular apparatus.

The supination movement in the subtalar joint is combined with movement in the articulatio talonaviculare, namely the adduction of the foot driven by the force of the m. tibialis posterior.

Pronation of the foot occurs simultaneously with the abduction of the Tarsal Bones driven by the peroneal muscle group.

During weight-bearing, if the lower leg twists outward (externally), it induces supination and adduction of the tarsal region. Internal (medial) Rotation of the lower leg causes abduction and valgus deviation of the foot.

Normally, the range of motion in the region of the first metatarsal and tarsus is within 20°; thus, the height of the medial longitudinal arch of the foot depends on the degree of flexion in this joint. The muscle responsible for flexing the foot in this joint is the m. peroneus longus. Consequently, the Maintenance of the arch is determined by the condition of the m. tibialis posterior and the m. peroneus longus.