Review Question - QID 3827

This patient presents with a chronic Achilles tendon rupture. The most appropriate treatment of this injury would be flexor hallucis longus tendon transfer with sliding V-Y advancement of the gastrocnemius-soleus complex aponeurosis.

The flexor hallucis longus (FHL) tendon is the most commonly used tendon transfer for these injuries. It is preferred to other tendon transfers as, (1) its axis of contractile force and function replicates that of the Achilles tendon, (2) it fires in phase with the gastrocnemius-soleus complex, (3) its anatomic location and retrieval avoids the neurovascular bundle, and (4) the tendon is expendable.

Wilcox et al. reviewed the treatment of chronic achilles tendon disorders with flexor hallucis longus tendon transfer/augmentation. They state the potential drawbacks of the FHL transfer/augmentation include (1) morbidity of the FHL harvest and (2) loss of great toe interphalangeal joint flexion strength resulting from the FHL transfer.

Den Hartog et al. performed 26 reconstruction procedures with flexor hallucis longus transfers for chronic Achilles tendonosis. They showed Ankle-Hindfoot Scale ratings improved from 41.7 (range, 23 to 63) preoperatively to 90.1 (range, 49 to 100) postoperatively, with no functional deficit, or deformity, of the hallux after transfer of the FHL tendon.

Figure A shows a positive foot sag, indicating loss of plantar flexion resting tone. Figure B shows a gapped defect in the skin overlying the Achilles tendon. Figure C shows debridement of the pseudotendon, leaving 5cm gap in the tendon. Illustration A shows the JAAOS 2009 article reporting a treatment algorithm for surgical treatment for chronic disease and disorders of the Achilles tendon.

Incorrect Answers:
Answer 1: Direct repair is uncommon form of treatment for most chronic ruptures as this has the potential for shortening and contracture of the gastrocnemius-soleus musculotendinous unit. However, it is generally accepted that approximately 1-2 cm gap will allow end-to-end repair.
Answer 2: Foreign body reaction has been observed with the use of carbon or polyester fiber synthetic grafts.
Answer 3: There has historically been poor outcomes with xenograft tendon with these injuries. Augmentation with soft tissue may be considered using medial and lateral aponeurotic fascial turndown flaps, but not classically with xenograft tissue.
Answer 4: Despite being described as an 'in-phase' tendon transfer for achilles tendon rupture, posterior tibialis tendon transfers are not considered the best choice for these injuries.