Determination of optimal screw positioning in flexor hallucis longus tendon transfer for chronic tendoachilles rupture

Abstract: Background: Neglected ruptures of the tendoachilles pose a difficult surgical problem. There are no data to determine the optimal positioning of the FHL tendon to the calcaneus. Methods: Two computer programmes (MSC.visualNastran Desktop 2002™ and Solid Edge® V19) were used to generate a human ankle joint model. Different attachment points of FHL tendon transfer to the calcaneus were investigated. Results: The lowest muscle force to produce plantarflexion (single stance heel rise) was 1355N. Plantarflexion increased for a more anterior attachment point. The maximum range of plantarflexion was 33.4° for anterior attachment and 24.4° for posterior attachment. There was no significant difference in range of movement when the attachment point was moved to either a medial or lateral position. Conclusions: A more posterior attachment point is advantageous in terms of power and the arc of motion (24.4°) is physiological. We recommend that FHL is transferred to the calcaneus in a posterior position. [Copyright &y& Elsevier]