Examination of the stability in the talocrural joint with special consideration of the function of the peroneal tendon sheath.

The structure and variations of the peroneal tendon sheaths of 69 formaldehyde-fixed cadaver ankle joints were studied both macroscopically and microscopically. The peroneal tendon sheath is a structure which is adapted to the mechanical requirements of the region overlying the lateral malleolus. It serves simultaneously as a guide and restraint for the peroneal tendons and as a lateral stabiliser of the upper ankle joint. This conclusion is based on examinations of thickness as well as light and polarisation microscopy. Mechanical cadaver studies of the stability of 24 ankle joints underlined the importance of the peroneal tendon sheath in stabilising the upper ankle joint. Defined lesions followed by suturing of the ligamentous structures and peroneal tendon sheath were performed with a simultaneous rotation drawer effect. A lateral opening was documented radiologically. It has been demonstrated that, although the thickness of the peroneal tendon sheath differs greatly from individual to individual, suturing is always important to stabilise the ankle joint after plantar flexion-supination-adduction trauma.