Effect of calcaneal osteotomy and lateral column lengthening on the plantar fascia: a biomechanical investigation.

Medial calcaneal displacement osteotomy or lateral column lengthening fusion has been advocated to augment tendon transfer in planovalgus foot deformity associated with chronic posterior tibial tendon insufficiency. It is hypothesized that plantar fascia tightening occurs with these procedures, helping to restore a more normal longitudinal arch. To investigate this further, nine fresh-frozen cadaver below-knee specimens were used. A flatfoot model was created by sectioning of the posterior tibial tendon, spring ligament, talonavicular capsule, and deltoid ligament. A liquid-metal strain gauge, calibrated to measure fractional changes in length, was sutured proximally to the origin and distally into the thickest portion of the medial band of the plantar fascia. Specimens were axially loaded to 400 N and plantar fascia strain was measured. Fractional length changes in the plantar fascia were then measured after a medial displacement calcaneal osteotomy and after a lateral column lengthening through the calcaneocuboid joint. Tightening of the plantar fascia did not occur with either medial calcaneal displacement or lateral column lengthening. The plantar fascia became significantly less taut with both medial displacement and lateral column lengthening. We found that lateral column lengthening produced significantly looser plantar fascia than did medial displacement of the calcaneal tuberosity.