MEDIAL MALLEOLAR STRESS FRACTURE SECONDARY TO CHRONIC ANKLE IMPINGEMENT

Abstract

Medial malleolar stress fractures are uncommon even in the sporting population. They tend to occur almost exclusively in athletes involved in sports involving running and jumping. We believe that stress fractures of the medial malleolus may be the end stage of chronic anteromedial ankle impingement in elite running and jumping athletes. Anterior impingement spurs are thought to be caused by repetitive microtrauma at the limit of dorsiflexion causing subperiosteal haemorrhage and subsequent ossification. More specifically the lower surface of the anterior tibia and the anterior part of the medial malleolus undergo similar trauma during severe supination injuries. Repetitive trauma to the cartilage from the kicking action in soccer is also thought to play a part, the cartilage responding by the formation of scar tissue and subsequent calcification.

We present five cases of elite athletes (three AFLplayers, one sprinter and one A Grade cricketer) who presented to our establishment with vertical stress fractures of the medial malleolus over a three year period (2004–7). In each case preoperative imaging revealed an anteromedial bony spur on the tibia. All patients had the fractures internally fixed and at the same sitting had arthroscopic debridement of the impingement spur.

Average time to union was 10.2 weeks (6–16). At most recent review (average 18 months (8–37)) all fractures had united and all patients had resumed sporting activity. No patient had suffered a further fracture of the medial malleolus.

We believe this region of impingement causes premature abutment of the talus on the tibia in the supination-adduction motion that in severe trauma leads to the vertical fracture through the medial malleolus according to the Lauge-Hansen classification. We therefore feel it should be addressed at the time of fracture fixation to reduce the re-fracture rate.