Review Question - QID 3090

The clinical photograph and radiograph demonstrate a modified Lisfranc amputation. The loss of the peroneus longus, peroneus brevis, EHL, EDL, and peroneus tertius insertions result in an equinovarus deformity due to the pull of the gastroc-soleus complex, posterior tibialis, and anterior tibialis.

Several surgical techniques have been described to address or prevent equinovarus deformities after Lisfranc amputation. Open or percutaneous achilles tendon lengthening, open gastrocnemius recession, or endoscopic gastrocnemius recession have shown to address the equinus deformity. Split tibialis anterior tendon transfer (STATT), 4th and 5th digit flexor-to-extensor tendons tenodesis, as well as peroneus brevis (PB) to peroneus longus (PL) tendon transfers have shown to address the varus deformity.

Early et al. state the Lisfranc amputation should be considered when there is inadequate soft tissue coverage for transmetatarsal amputation or instability at the LisFranc joint. In addition, they comment that the deforming forces, the gastroc-soleus complex and posterior tibialis, are primarily innervated by the S1 nerve root.

Figures A through C show clinical and radiographic images of a modified Lisfranc amputation. The classic Lisfranc amputation describes transaction of the first, third, fourth, and fifth tarsometatarsal joints. The second TMT is usually left in place, as it provides stability for the middle cuneiform. These radiographs show a midfoot amputation carried out more transversely across the bones of the midfoot.

Incorrect Answers:
Answers 1-4: The equinus deformity occurs after the elimination of extensor digitorum longus and extensor hallucis longus muscles, which cause an imbalance between the posterior compartment and the anterior compartment muscles that across the ankle. The varus deformity occurs when tibialis anterior and posterior compartment muscles overpower the eversion strength of the peroneus brevis muscle.