Brachymetatarsia

Brachymetatarsia(short metatarsal) is a hereditary anomaly that occurs as a result of premature closure of the growth center of a metatarsal or metatarsals. When multiple metatarsals are involved the name is brachymetapody. Most commonly the fourth metatarsal is affected. The other metatarsals continue to grow and the length becomes exaggerated.

Brachymetatarsia can result from trauma to the metatarsal or from an infectious process. It has also been associated with Down's Syndrome, Sickle-cell anemia, and polio. The defect is not always noted at birth but, becomes more evident between 4-15 years of age. Brachymetatarsia may occur unilateral or bilaterally, though mostly seen on one side.

Clinically, the younger patient notices a shortened or floating toe. Calluses may develop under the adjacent metatarsal heads with pain. The adjacent toes underlap the involved toe.

Radiographs reveal a short, underdeveloped metatarsal with deficient bone content and osteoporosis of the metatarsal head. The affected toe is usually straight, in an extended position, and floats above the weight-bearing plane. Conservatively one may use orthotics.

For surgical correction bone lengthening procedures are performed, bone grafts may be inserted, extensor tenotomy performed, and skin plasty may be performed. Below knee non-weight bearing cast may be applied. Callus distraction (with pins and external fixation) is another procedure performed to attempt to lenghthen the metatarsal. Soft tissues can gradually elongate with the bone. Postoperative non-weight bearing is used for 2-3 months pending xrays evidence of bone healing.

Complications include risk of neurovascular compromise, non-union, collapse of the graft if implemented, painful pseudoarthrosis and painful limitation of motion at the joint.

Bibliography

  • Banks, Alan S., et al McGlamry's Comprehensive Textbook of Foot and Ankle Surgery.Philadelphia:Lippincott Williams and Wilkins, 2001.
  • McGlamry ED, Fenton CF. Brachymetatarsia:a case report. J AM Podiatry Assoc 1983;73:75-78.
  • Robinson J, Ouzounian T. Brachymetatarsia:congenitally short third and fourth metatarsal treatment by distraction lengthening- a case report and literature summary. Foot Ankle Int 1998;19:713-718.
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