Recovery of the posterior tibial muscle after late reconstruction following tendon rupture.

The purpose of this study was to determine the recovery potential of the posterior tibial muscle after late reconstruction following tendon rupture in stage II of posterior tibial tendon dysfunction. Fourteen patients (18 women, 6 men; mean age 59.8 years) were investigated 47 months (range, 24-76 months) after surgical reconstruction of a completely ruptured posterior tibial tendon (end-to-end anastomosis, side-to-side augmentation with the flexor digitorum longus tendon) in combination with a distal calcaneal osteotomy with a tricortical iliac crest bone graft for lengthening of the lateral column. At follow-up, clinical and radiological investigations were performed, including strength measurement and qualitative and quantitative MRI investigation. The overall clinical results were graded excellent in 12 patients, good in one, fair in one, and poor in none. The average ankle-hindfoot score (American Orthopaedic Foot and Ankle Society) improved from preoperatively 49.1 (range, 32-60) to 93.1 (range, 76-100) at follow-up. The functional result correlated with patient's satisfaction and sports activities (p <.05). All patients showed a significant strength of the posterior tibial muscle on the affected side, but it was smaller than on non-affected side (p <.05). The mean posterior tibial muscle strength was 75.1 N on affected and 104.9 N on nonaffected side, corresponding to a ratio of 0.73 between the two legs. The mean area of the posterior tibial muscle was 1.89 cm(2) on affected side, and 3.48 cm(2) on nonaffected side, corresponding to a ratio of 0.55 between the two legs. While fatty degeneration for the posterior tibial muscle was found in all patients, it was found to decrease with increasing strength of the posterior tibial muscle (p <.05) and muscular size (p <.05). On postoperative MRI, the posterior tibial tendon could be found to be intact in all patients. The recovery potential of the posterior tibial muscle was shown to be significant even after delayed repair of its ruptured tendon. A ruptured and/or diseased posterior tibial tendon should not be transected as it excludes any recovery possibilities of the posterior tibial muscle.