Physiological and Pathological Development of calcaneal apophysis in Children

Abstract

The apophysis of the calcaneal bone forms an insertional region for the strong plantarflexors with the Achillis tendon and serves as an origin for the plantar aponeurosis and the short intrinsic foot muscles. Both components create a tendinous sling whithin which the apophysis acts as a pivot, which functions when it runs a straight course and its tension is adequate. This mechanism results in combined tractional and compressional forces which work together with the ground reaction forces during gait as molding elements of the calcaneous bone. Every longer lasting change in the magnitude and distribution of these forces can be followed by structural adaptations especially during the growth period. Furthermore the calcaneal apophysis functions as a connecting link between the ankle and thigh bones on one side and the mid- and forefoot region on the other side. When studying the causal relationships which influence the apophyseal growth and shape intrinsic and extrinsic components must be distinguished. Every analysis of calcaneal pathologies should use clinical and instrumented diagnostics. Any classification must separate between bony and soft tissue elements and consider structural and functional influences in three planes. If an exact classification can be established an individual hypothesis must be formulated out of which therapeutic measures can be developed. Treatment must focus on the pathologic changes of shape as well as on functional aspects. A thorough knowledge of the normal development and function of the calcaneal apophysis serves as a basis for further understanding and treating pathologic changes of this hitherto only sparsely investigated functional region.