Sonography valuable in determining surgery in peroneal nerve injuries in the knee

Peroneal nerve injury in traumatic knee dislocation is common, especially in high-speed collisions or sports injuries. "Because of its superficial course and proximity to the underlying bone, the peroneal nerve is susceptible to direct injury during contact sports and to indirect injury during knee trauma," said the authors.

Clinically, the nerve is usually inspected during reconstructive knee surgery if pain and a sensory deficit on the anterolateral skin of the leg is apparent on initial presentation. "This new examination technique should allow physicians to plan the route of surgery prior to the operation," said Hannes Gruber, MD, lead author of the study.

Traumatic knee dislocation requires immediate surgical repair to restore joint function. A concomitant traction injury of the peroneal nerve is reported to exist in up to 25% of cases and is often initially overlooked. In patients with major nerve lesions, immediate surgical nerve repair might be necessary to avoid irreversible loss of neural function, said the report. "An immediately repaired nerve shows better healing than one after a delayed diagnosis," said Dr. Gruber. The need for precise knowledge regarding the length and exact localization of a damaged nerve segment is essential for surgical intervention.

In all nine patients of the study with peroneal nerve palsy, the peroneal nerve injuries and their degree were clearly identified and visualized by means of sonography, reports the study. The sonographic findings were confirmed directly by surgical reinspection in four patients. The follow-up examinations, utilizing sonographic assessment, of the five remaining conservatively treated patients showed restitution of normal peroneal nerve morphology after six months.

The results of the study concluded that sonography allows major or minor injuries to be detected and the level and extent of the nerve lesion, if present, to be localized. This information is important for planning the most appropriate therapy (be it surgical or conservative) and helps to set the path for an optimum future prognosis for these lesions, which may otherwise result in long-lasting medical and socioeconomic problems in a usually young and active group of patients.

The study appears in the November 2005 issue of the American Journal of Roentgenology (AJR).

A PDF of the study is available upon request to reporters.

AJR Nov 2005;185:1119-1125

---

---