Tendon transfer combined with calcaneal osteotomy for treatment of posterior tibial tendon insufficiency: a radiological investigation.

We present the radiographic results after flexor digitorum longus tendon transfer combined with a medial displacement calcaneal osteotomy for the treatment of posterior tibial tendon insufficiency. Eighteen patients with posterior tibial tendon insufficiency were reviewed from 12 to 26 months after surgery. The 15 women and 3 men had a mean age of 54 years (range, 38-72 years). The talar-first metatarsal and talonavicular coverage angles were measured before and after surgery on the anteroposterior weightbearing radiographs. The mean preoperative talar-first metatarsal and talonavicular coverage angles were 21 degrees (range, 3-45 degrees) and 34 degrees (range, 0-55 degrees), respectively. The mean postoperative values for these angles were 8.5 degrees (range, 0-35 degrees) and 21 degrees (range, -30-45 degrees), respectively. The mean talar-first metatarsal angle decreased from 21 degrees to 8.5 degrees, a mean improvement of 12.5 degrees, and the mean talonavicular coverage angle decreased from 34 degrees to 21 degrees, a mean improvement of 13 degrees. On the lateral weightbearing radiographs, the talar-first metatarsal angle and the distance from the medial cuneiform to the floor were measured before and after surgery. The mean preoperative values were -22 degrees (range, -10 to -40 degrees) and 9 mm (range, 1-19 mm), respectively. The mean postoperative values were -9 degrees (range, +5 to -25 degrees) and 16 mm (range, 10-28 mm), respectively. The mean talar-first metatarsal angle decreased from -22 to -9 degrees (a mean improvement of 13 degrees), and the distance from the medial cuneiform to the floor increased from 9 to 16 mm (a mean improvement of 7 mm). We conclude that the use of a combined medial displacement osteotomy of the calcaneus with a tendon transfer for treatment of posterior tibial tendon insufficiency may offset the inherent weakness of the flexor digitorum longus transfer by reducing the antagonistic deforming force of heel valgus.