Transverse Weber A fracture atrophic non-union. A single centre case series

Abstract

Introduction: Weber A ankle fractures are isolated fibula fractures distal to the level of the ankle joint line. They are regarded as stable injuries that usually heal successfully without intervention. We have identified several patients that have developed symptomatic atrophic non-union of transverse Weber A fractures that are not simple avulsion fractures of the anterior talo-fibular ligament. We explored variations to the blood supply of the distal fibula as a potential cause of this rare complication.

Cases: Five patients presented with ongoing ankle pain following a period of non-operative management. All shared a similar transverse atrophic non-union fracture pattern.Surgical management with open reduction and internal fixation with or without the use of bone graft achieved successful union and resolution of symptoms in all cases.

Conclusions: Atrophic fracture non-unions usually result from a disruption to the blood supply at the site of injury. The arterial supply to the distal fibula consists of a complex of arterial loops which usually enable fracture healing. However, there are anatomical variations to the blood supply that potentially could account for the rare outcome of non-union of Weber A fracture patterns. Weber A fractures are generally benign ankle fractures that heal well with non-operative treatment. No alterations should be made to the management of such injuries, but patients should be counselled about the risk of a symptomatic non-union outcome.

Keywords: Ankle fracture; Fibula blood supply; Non-union.

Fig. 1

Anterior-posterior radiographs of the five cases of transverse Weber A fractures at non-union.

Fig. 2

Anterior-posterior radiographs of example of a united Weber A fracture following open reduction and internal fixation for non-union.

Fig. 3

Blood supply to distal fibula and anatomical variations. A – The most common arterial blood supply to the distal fibula with the ALMA arising below the level of the ankle joint. A branch of the LTA provides some peripheral supply through the ligaments comprising the lateral ankle capsule. B – The most common anatomical variant in blood supply (19% of population). The ALMA originates at the level of the ankle joint. C - The absent ALMA (8% of population). Arterial abbreviations: ALMA - anterior lateral malleolar artery; ATA - anterior tibial artery; LTA - lateral tarsal artery; PA - peroneal artery; PPA - perforating peroneal artery.