Severe open ankle sprain (SOAS): a lesion presenting as a penetrating soft tissue injury.

The objective of this retrospective case study was to describe the incidence and clinical features of severe open ankle sprain (SOAS), defined as a tear of the lateral or medial collateral ligaments with an associated transverse tear of the skin over the corresponding malleolus. To this end, we reviewed the medical records of patients with SOAS managed between January 2005 and January 2009, using the databases of 3 different orthopedic trauma centers. Our review revealed 9 patients with SOAS, 7 (77.77%) of which involved the lateral ligaments and 2 (22.22%) of which involved the medial ligaments. The median age was 32 (range 21 to 45) years, and the injury occurred as a result of a motor vehicle accident in 6 (66.67%) patients, and as a result of a fall from a height in 3 (33.33%) patients. Two tendons were damaged in 2 (22.22%) patients, the deep fibular nerve (deep peroneal nerve) in 2 (22.22%) patients, and the anterior tibial artery in 1 (11.11%) patient. The only abnormality on plain radiographs was pneumarthrosis, which was present in 5 (55.56%) patients. The incidence of SOAS is rare, accounting for 0.002% (9/438,000) of all trauma cases and 0.22% (9/4142) of all cases of ankle trauma. The diagnosis was confirmed by intraoperative stress-maneuvers in all 9 patients. In conclusion, SOAS should be suspected in patients who present with a traumatic skin wound over the malleolus.