Tendoscopic Peroneus Longus to Brevis Tendon Transfer Technique for Flexible Cavovarus Deformity With Medial Forefoot Overload and Chronic Diabetic Foot Ulceration

Glycosylation of type 1 collagen fibers in diabetes mellitus results in contractures of the gastroc-soleus, tibialis posterior, peroneus longus muscle groups and plantar fascia, which may lead to progressive cavovarus deformity. The medial forefoot is reported to be the third most common location of chronic plantar diabetic foot ulceration (CPDFU), occurring because of increased plantar pressure secondary to deformity and loss of protective sensation. With high recurrence rates after nonoperative treatment with total contact casting and low patient adherence to orthotic footwear, surgical offloading techniques are increasingly reported to provide more reliable ulcer healing. Achilles tendon lengthening plus open peroneus longus tendon lengthening aid low recurrence rates. However, a 10-fold increase in wound complications after open surgery in the diabetic patient population has prompted exploration of less-invasive techniques. We present a tendoscopic peroneus longus to brevis transfer technique to be used in combination with percutaneous Achilles tendon lengthening as a surgical offloading strategy for first metatarsal head CPDFUs. The aim of this procedure is to decrease the peak plantar pressure of the first metatarsal head by eliminating the plantar flexion effect of the contracted peroneus longus muscle while also counteracting the deforming force of tibialis posterior by increasing the power of peroneus brevis.