Deep fascia on the dorsum of the ankle and foot: extensor retinacula revisited.

This study revisits the anatomy of the deep fascia over the distal leg, ankle, and dorsum of the foot. The arrangement of the deep fascia in these regions was recorded in 14 lower limbs of adult cadavers using photographs and drawings. The fascial layer from all three sites was subsequently removed in toto, and serial thickness measurements were made along its entire length. In addition, fiber disposition was studied under polarized light, and sections were stained to demonstrate collagen. The arrangement of deep fascia is complex. A common and novel finding at all levels is a crisscross, lattice-like arrangement of fibers. There was little evidence of the clearly defined sturdy band of the superior extensor retinaculum (SER) or of the Y-shaped inferior retinaculum (IER) commonly illustrated in topographical anatomy texts. The SER is a complex area with several thickenings commencing about 3 cm proximal to the tip of the lateral malleolus and gradually increasing to reach a maximum of 270 microm about 5 cm above the malleolus, then gradually returning to original thickness, about 9 cm above the malleolus. Fibers crossing diagonally to each other are a feature of the region. The IER characteristically has two forms: either a cross-shaped band (9 specimens) or a thickened "node" with small extensions radiating toward the malleoli (5 specimens), located about 1-2 cm distal to the lateral malleolus and centred over the common tendon of extensor digitorum where it has maximum thickness (430 microm). The deep fascia is thickened and firmly attached over both malleoli and to the tarsals and metatarsals along both borders of the foot. In general, the deep fascial structures were thicker in males than those in females.