Peroneal nerve injury with foot drop complicating ankle sprain--a series of four cases with review of the literature.

Foot drop has many etiologies. One rarely mentioned and often neglected reason for foot drop is an acute inversion sprain of the ankle. Over the past 14 years, a collection of 32 cases of foot drop have been compiled in our orthopaedic and physiatric practices. All cases had appropriate evaluations, including electrodiagnostic studies (electromyography and nerve conduction studies) to determine the location and type of injury. Treatment and follow-up are also discussed. Of the 32 case studies, four were caused by a straightforward acute inversion sprain of the ankle. These cases are described with the electrodiagnostic evaluations, treatments, and outcomes. Proposed mechanisms for this type of foot drop are discussed, including traction and compression of the common peroneal nerve as it winds around the neck of the fibula, and possible compression by hematoma. Surgical versus conservative treatment is described. The functional impairment associated with foot drop is detailed.