Nerve entrapment by a firmly wrapped Baker cyst.

Baker's cysts as a clinical entity are among the most infrequent cause of peripheral nerve entrapment and usually produce a strong positive pressure within the knee resulting in the rupture of the joint capsule. An unusual case with muscular and sensorial weakness due to compression of the peroneal nerve around the fibular head by a Baker cyst is presented in this article. Clinical and electromyographical findings shown peroneal nerve entrapments in the popliteal fossa. Peroneal nerve decompression by synevectomy resulted in clinical and electromyographical improvement.