A simple approach for determining tendon limb length in open Achilles lengthening: technical note.

Estimating the appropriate tendon length and associated skin incision needed to achieve a plantigrade foot without compromising function are essential steps in open Achilles tendon lengthening. Here we describe a technique using basic surgical instruments referencing anatomic landmarks without the need for radiographs. The center of ankle rotation in the sagittal plane is found referencing the tip of the medial malleolus. This point is translated to the plantar surface of the foot, and a straight instrument in line with the foot is used to make a mark at the posterior calcaneal fat pad. The straight instrument is then rotated (representing the plantar surface of the foot) as if dorsiflexing the ankle along the axis of the transposed tibiotalar joint from a plantar-flexed position to the desired final position and a second mark is made at the posterior heel. The distance between the marks is measured, representing the amount of Achilles lengthening required. The skin incision and tendon limb lengths area a sum of the operative correction and the amount of desired tendon overlap, typically 2 cm of tendon overlap is optimal to allow for suture fixation, ensure tendon healing, and maintain the integrity of the repair. A Z-type lengthening is then performed using this tendon limb length. This technique allows an accurate and simple approach to lengthening the Achilles tendon. In this way the ideal tendon limb length is selected to optimize function while minimizing incision length, associated wound complications, inadequate lengthening, and overlengthening. Level of evidence: Technical note, Level V.