The mechanics behind the image: foot and ankle pathology associated with gastrocnemius contracture

Contracture of the gastrocnemius musculature is a prevalent finding in the setting of foot and ankle pathology. Tightness of the posterior musculotendinous structures in the leg limits ankle range of motion and affects an equinus posture of the foot. Increased contact pressures are generated in the plantar foot with weightbearing. The resultant overload of the ligaments and the intrinsic muscles of the midfoot and forefoot is manifest in a variety of pathologic processes. The altered mechanics contributes to, among other conditions, ankle impingement, plantar fasciitis, midfoot arthritis, posterior tibial tendon dysfunction, forefoot overload, diabetic ulceration, and Charcot arthropathy. Effective management of these conditions includes addressing the underlying gastrocnemius contracture as well as the related foot and ankle pathology. Here we describe the underlying biomechanical abnormalities and radiographic findings in these pathological conditions of the foot and ankle associated with gastroequinus contracture. An awareness and understanding of the pathomechanics should enable the radiologist to better appreciate the form and function associated with the image.