Current Concepts In Surgical Offloading Of The Diabetic Foot

Nicholas Todd, DPM, Meagan Jennings, DPM, FACFAS, and Shannon Rush, DPM, FACFAS

Surgical Options For First Ray Ulceration

Wounds of the plantar aspect of the great toe (hallux interphalangeal joint ulcerations) are extremely common in neuropathic patients. The etiology of the ulceration arises from increased plantar pressure due to limitation of the first metatarsophalangeal joint (MPJ). Alterations in plantar pressure can arise from interphalangeal sesamoids or hallux rigidus. Simple removal of the interphalangeal sesamoid is indicated for a prominent sesamoid without hallux rigidus.

   Keller arthroplasty may also be indicated for cases of recalcitrant hallux ulceration. One must exercise caution as there is additional transfer pressure to the second ray as a result of this procedure. Direct attention to an Achilles lengthening or gastroc recession if there is concern for transfer ulceration. Armstrong and colleagues analyzed complications and outcomes of first MPJ arthroplasty (Keller arthroplasty) in comparison to the standard, non-surgical management of hallux interphalangeal joint wounds.1 They found the surgical group healed quicker (24 days versus 67 days respectively) with recurrence being significantly lower.

What You Should Know About First Metatarsal Head Ulcerations

A common area of concern is the first metatarsal head. This area is prone to ulceration, which can occur due to a rigid or a flexible cavus deformity as well as tendon imbalances. It is imperative that the foot and ankle surgeon recognizes the biomechanical etiology. Hansen coined the term “peroneus longus overpull.”2 A careful examination of patients with sub-first metatarsal head ulceration may allow the surgeon to discover an overdrive of the peroneus longus creating a focal first ray cavus. A simple clinical exam of the first ray will determine if the ray is fixed or flexible in the sagittal plane. Active ankle plantarflexion with plantar pressure beneath the first and second metatarsal heads will highlight the sagittal plane overdrive of the first ray.

   We feel the most appropriate treatment for sub-first metatarsal head ulceration secondary to long peroneal overdrive is a tenodesis of the peroneus longus to the peroneus brevis. The surgical approach centers over the cuboid parallel to the fourth ray. One can easily locate the peroneal tendons. Trace the peroneus longus to the plantar cuboid tunnel and transect it. One can anastomose the distal end of the peroneus longus to the lateral band of the plantar fascia in this area. Sew the proximal end of the peroneus longus tendon through a longitudinal incision in the peroneus brevis. Postoperatively, the patient wears a walking pneumatic boot and may ambulate immediately.

   In the case of a fixed deformity, one can also correct this in a number of ways. We prefer a distal oblique dorsal closing wedge osteotomy for relatively small amounts of correction and a tarsometatarsal arthrodesis for any correction greater than 5 mm.

Key Insights On Offloading Lesser Metatarsal Parabola Ulcerations

Neuropathic ulcerations under the lesser metatarsal heads can arise from a variety of biomechanical faults. These include but are not limited to: abnormal metatarsal parabola; transfer lesions secondary to first ray pathology; and plantar fat pad atrophy. Ankle equinus almost always plays a role to some degree in the pathogenesis of forefoot plantar neuropathic ulcers.

   We advocate early percutaneous Achilles release as an important adjunct to wound care and offloading for plantar forefoot ulcerations. One can perform a percutaneous Achilles release with local anesthesia in many instances and manage the ulceration with a short leg cast.

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