Distal soft tissue procedure in hallux valgus surgery: biomechanical background and technique.

The distal soft tissue procedure has evolved into an indispensable additional surgical procedure to increase the corrective effect in hallux valgus surgery. Considering the biomechanical development of hallux valgus deformity, degenerative changes of the soft tissues around the first metatarsophalangeal joint contribute much more to the deformity than changes in the bony structures which can rather be seen as degenerative changes secondary to the deformity. Thus the principles in hallux valgus correction should aim to reverse all pathogenetic steps leading to deformity: release of the contracted lateral soft tissue structures, tightening of the torn-out medial structures and reduction and rebalancing the first metatarsal head onto the sesamoid complex. The scientific discussion over the last decades has clarified the impact of different surgical steps and methods on the efficacy of the lateral release, the risk of creating overcorrection or instability of the joint and the risk of avascular necrosis of the first metatarsal head. According to anatomical and clinical data, a lateral soft tissue release can be combined with a distal metatarsal osteotomy, provided that the osteotomy is performed in a defined safe zone without increasing the risk for avascular necrosis of the first metatarsal head. Transecting the lateral metatarsosesamoid suspensory ligament is the key to a successful lateral release in hallux valgus surgery. Release of the deep transverse metatarsal ligament and the adductor hallucis muscle does not contribute to hallux valgus correction. The lateral short sesamophalangeal ligament and the plantar attachment of the articular capsule should be preserved to avoid possible joint instability. Thus today, the distal soft tissue procedure cannot be seen only as a supplementary surgical procedure in cases where the bony procedure needs additional correction, but rather is an indispensable procedure to restore the physiological situation and function of the first metatarsophalangeal joint.