PURPOSE: This study was performed to investigate the dynamic effect of medial displacement calcaneal osteotomy (MCO) on the calcaneal inversion. MATERIALS AND METHODS: 10 fresh-frozen, intact cadaver foot-ankle specimens were tested, using a custom loading apparatus at an orientation consistent with the early heel rise portion (40%) of the gait cycle. Calcaneal inversion was measured with identical ground reac-tion force and tendon force, before and after MCO. RESULTS: Calcaneal inversion was 2.1+/-2.4degrees in the pre-osteotomy condition and 3.7+/-3.1degrees after MCO. Calcaneal plantar flexion was 7.1+/-0.7degrees in the pre-osteotomy condition and 8.8+/-1.8degrees after MCO. Increases of calcaneal inversion and flexion were significant (intact vs. MCO), (p< 0.05). CONCLUSION: The inversion capability of the Achilles tendon was enhanced by lengthening its moment arm when its insertion was displaced medially following MCO. MCO, therefore, could compensate for the weaker inverting power of the transferred toe flexor, when treating stage II posterior tibial tendon insufficiency.
Achilles Tendon ; Arm ; Cadaver ; Calcaneus ; Gait ; Heel ; Osteotomy* ; Posterior Tibial Tendon Dysfunction ; Tendons ; Toes

PURPOSE: The proximity of the medial soft tissue structures to a posterior calcaneal osteotomy (PCO) was examined to determine which structures are at risk of injury. MATERIALS AND METHODS: A PCO was performed on 12 adult frozen cadaver feet. At the lateral side of each specimen, the inclination of the osteotomy line was 45degrees to the plantar aspect of the foot and its proximal end was began approximately 10 mm anterior to the posterosuperior corner of the calcaneus. Two different PCOs were made in order to include any variations in the osteotomy. Using a guide device to direct the osteotomy, the PCOs were performed 10degrees anteromedially in half of the specimens and 10degrees posteromedially in the other half. The medial side of the hindfoot was carefully dissected after the PCO had been fixated with K-wires. RESULTS: The most inferior portion of the osteotomy was 8.1 mm anterior to the inferior tubercle. The structures found closest to the osteotomy on the medial side were the medial head of the quadratus plantae (QP) and the branches of the lateral plantar nerve (LPN). In both osteotomies, the nerve to the abductor digiti quinti (ADQ) and calcaneal branch of the LPN crossed the osteotomy site. The thickness of the soft tissue coverage at the crossing site medially averaged 2.3 mm at the nerve to the ADQ and 5.9 mm for the calcaneal branch. In all specimens, the soft tissue coverage was thinner at the more inferior aspect of the osteotomy. No major neurovascular structures, such as the medial and lateral plantar arteries and nerves, crossed the osteotomy site. CONCLUSION: In the PCO, the structure most at risk is the medial head of the QP and the nerve to the ADQ, which is followed by the calcaneal branch of the LPN. Care should be taken for these nerve injuries, particularly at the inferior portion of the osteotomy due to the thinner coverage of the intervening soft tissue. The PCO can be safely carried out without involving the major neurovascular bundle of the foot, when the inclination of osteotomy line is 45degrees to the plantar aspect and its proximal end begins within 10 mm anterior to the posterosuperior corner of the lateral side of the calcaneus.
Adult ; Arteries ; Cadaver ; Calcaneus ; Foot ; Head ; Humans ; Osteotomy*