Outcomes of a transtendinous flexor hallucis longus transfer for reconstruction of chronic Achilles tendon ruptures

C. Lever, H. Bosman, A. Robinson

Introduction: Patients with neglected rupture of the Achilles tendon typically present with weakness and reduced function rather than pain. Shortening of the musculotendinous unit and atrophy of the muscle belly in chronic rupture potentially leads to poorer recovery following tendon transfer. Few papers have looked at the outcomes of FHL reconstruction specifically in neglected TA rupture. Of those that have none report functional outcomes following a transtendinous repair.

Methods: Twenty patients with irreparable unilateral tendoachilles ruptures treated with transtendinous FHL reconstruction between 2003 and 2011 were reviewed. Achilles Tendon Rupture Score (ATRS), AOFAS hindfoot score, Tegner score and SF12 were recorded. Standard isokinetic assessment of ankle plantarflexion was performed with a Cybex dynamometer. Great toe flexion strength was tested clinically.

Results: The mean age at surgery was 53 years (22-83 years). Mean time from rupture to surgery was 7 months (1-36 months). Follow up ranged from 29-120 months (mean 73 months). Sixteen patients were completely satisfied and four moderately satisfied. The mean ATRS was 80 (range 25-100) and AOFAS 94 (range 82-100). Postoperative Tegner score showed a reduction by one level from pre-injury (mean 5.1 pre injury to 4.3 post surgery). No cases of re-rupture were encountered. Six patients had wound issues.
The mean maximal strength of ankle plantar flexion on the operated leg 95Nm (41-163) was less than the non-operated leg 123 Nm (50-190Nm). The average difference in strength was 24%. The operated hallux had only 40% of strength in flexion of the contralateral toe. There were no floating toes.

Conclusion: Transtendinous FHL transfer for late presenting Achilles tendon ruptures provides reliable long term function and reasonable ankle plantar flexion strength. Long FHL harvest has little morbidity and lack of a distal tenodesis did not result in any notable functional loss or alignment issues to the great toe.