Addressing A Unique Skin Ulceration In A Patient With Neuromuscular Disease

Author(s): 
Eric Feit, DPM, FACFAS, and Armin Feradouni, DPM

These authors discuss the diagnostic workup and eventual surgical treatment to resolve a chronic ulcer in a patient with a history of polio and spina bifida.

A 32-year-old male presented to our office with a chief complaint of a non-healing skin ulceration on the dorsum of the left foot (see figures 1,2,3). The patient had a history of polio and spina bifida, and ambulates with below-knee custom ankle foot orthoses and crutches. He had been walking comfortably for years and did not have a prior skin ulceration on this foot. He denied trauma and his brace did not apply pressure in the area. The patient wore extra-depth shoes and they fit well.

   He had multiple surgeries as a child. These surgeries included an Achilles tendon lengthening, multiple tendon transfers and a subtalar joint arthrodesis. The patient says the shape of his left foot has changed slightly over the past six months. The hallux is flaccid with no muscle function and as a result, he sometimes trips when walking.

   The physical exam revealed a dorsal skin ulceration over the first metatarsal. The ulceration was 15 x 18 mm in size and 3 mm in depth. There was no undermining. There was yellow serous drainage without an odor. Initially, the patient had erythema at the periphery of the wound, which resolved after one week with oral amoxicillin/clavulanic acid (Augmentin, GlaxoSmithKline). The first metatarsal was elevated relative to the second metatarsal and was in spasm. There was also spasm and tightness of the anterior tibial tendon, causing mild inversion. The left hallux was dysfunctional and was in a “dropped” position relative to the first metatarsal.

   Manual muscle testing of the left foot and leg revealed severe weakness of the extensor tendons to the foot (1/5) and hallux (0/5), and testing of the plantar flexors of the foot revealed mild but decreased muscle strength (2/5). The posterior tibial and anterior tibial tendon had minimal muscle strength (1/5) and the peroneal tendons were also weak (1/5). The quadriceps and hamstring muscles were more functional but still weak (3/5). The ankle joint dorsiflexion was 0 degrees with the knee flexed and extended. The tendon was very thin due to previous surgery during the patient’s childhood. The neurologic exam revealed absent sharp/dull sensation and light touch to the foot both dorsally and plantarly. The vascular exam was within normal limits with palpable and normal dorsalis pedis and posterior tibialis arteries (+3/4).

   I initially performed conservative treatment with local wound care including debridement and topical medications such as sulfadiazine (Silvadene), mupirocin (Bactroban) and Amerigel (Amerx Health Care). The wound continued to persist and the patient required surgical repair to help resolve the ulceration and prevent recurrent infection.
Pre-op radiographic evaluation revealed first metatarsal elevatus and a plantarflexed hallux at the metatarsophalangeal joint (see figures 4 and 5). The planned procedures included an anterior tibial tendon lengthening, a first metatarsal (Juvara-type) plantarflexory oblique osteotomy and a first MPJ arthrodesis (see figures 6 and 7). The patient healed unremarkably and has been ambulating with tennis shoes and his custom AFO without a recurrence of the skin ulceration for more than six months now. He has residual venous stasis edema, which is improving weekly.

Pertinent Insights On The Impact Of Neuromuscular Disorders

Neuromuscular disorders often result in dysfunction of the lower motor neuron. Hallmarks of these disorders include muscle weakness, decreased muscle tone, hyporeflexia or areflexia, muscle atrophy and fasciculations. The patient had all of these diagnostic hallmarks.

   Although poliomyelitis is generally a non-progressive disorder, some patients will develop progressive weakness, fatigue and joint pain. In addition to the polio, spina bifida can also cause a foot drop and result in muscle dysfunction of the lower extremity. This patient had spina bifida occulta as a child and the condition only affected one vertebra in the lumbar spine. This resulted in a gap in the vertebra, which typically fills in with fibrous tissue eventually. The patient did not have a clinical protrusion of the spinal cord.

   This patient was clinically stable for years and was in a chronic phase of his disease. Bracing and extra depth shoes had been working very well for years. When the patient walks, he leans to his left side and this results in a functional limb length discrepancy. This may have contributed to his first metatarsal elevatus and progressive contracture of the anterior tibialis tendon.

   Due to the continuous tension on the skin as a result of the first metatarsal elevatus, the ulceration was not going to heal. Therefore, I chose the aforementioned the surgical procedures to help alleviate spasm on the foot and realign the first metatarsal. The first MPJ arthrodesis eliminated the “hallux drop” and the patient is walking better without tripping now.

   Dr. Feit is a Fellow of the American College of Foot and Ankle Surgeons, and is board-certified by the American Board of Podiatric Surgery. He is in private practice in Torrance and San Pedro, Calif.

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