Drop foot is typically caused by neurologic disease such as lumbar disc herniation, but we report two rare cases of deep peroneal nerve palsy with isolated lateral compartment syndrome secondary to peroneus longus tears. Both patients developed mild pain in the lower legs while playing sport, and were aware of drop foot. As compartment pressures were elevated, fasciotomy was performed immediately, and the tendon of the peroneus longus was completely detached from its proximal origin. The patients were able to return their original sports after 3 months, and clinical examination revealed no hypesthesia or muscle weakness in the deep peroneal nerve area at the time of last follow-up. The common peroneal nerve pierced the deep fascia and lay over the fibular neck, which formed the floor of a short tunnel (the so-called fibular tunnel), then passed the lateral compartment just behind the peroneus longus. The characteristic anatomical situation between the fibular tunnel and peroneus longus might have caused deep peroneal nerve palsy in these two cases after hematoma adjacent to the fibular tunnel increased lateral compartment pressure.
Keywords: Deep peroneal nerve palsy; Lateral compartment syndrome; Peroneus longus tear.