Features
Lyndon Mason is a Consultant Trauma and Orthopaedic Surgeon in the Liverpool University Hospitals Foundation Trust. Lyndon is the foot and ankle trauma lead in the Liverpool Orthopaedic Trauma Service and has published widely on foot and ankle trauma management. He is the chairperson elect this year for the outcomes committee in the British Orthopaedic Foot and Ankle Society.
The posterior malleolar fracture – is the rule of a third or use of percentages an orthopaedic myth?
Lyndon Mason, Andrew Molloy and Gavin Heyes
Andrew Molloy is a Foot and Ankle Consultant in Liverpool University Hospital NHS Foundation Trust. His work has been highly regarded internationally. He was one of the founding outcome committee members in the British Orthopaedic Foot and Ankle Society.
Gavin Heyes is a Consultant Trauma and Orthopaedic Surgeon in the Liverpool University Hospitals Foundation Trust. Gavin specialises in trauma and foot and ankle surgery including the management of diabetic foot disease. His research interests include trauma and foot and ankle surgery.
28 | JTO | Volume 09 | Issue 01 | March 2021 | boa.ac.uk
The Hunterian Professorship is one of the proudest traditional honours of the Royal College of Surgeons of England and is bestowed to surgeons of eminence who have richly contributed to the field of surgery by original research or innovation. It is named after the pioneering surgeon, John Hunter, and has been awarded annually by the college since 1810. Professor Lyndon Mason delivered his Hunterian Lecture on his ground-breaking work on ankles fractures at the BOA Virtual Congress in 2020.
T
he posterior malleolar fracture of the ankle has come under major scrutiny over recent years with a marked increase in the published literature on the subject. Significant variations in morphology have been described which reflect differing mechanisms of injury1,2. Despite this there are still some that consider fracture fragment size in their decision making3,4. The purpose of this paper is to outline the evidence that formed the basis for the traditional mantra that, “minimal posterior malleolar fractures involve less than one-third of the articular surface” or as some authors quote 25%5. Is there any clinical or
biomechanical evidence to substantiate this claim? Can size of posterior malleolus fracture be accurately assessed by radiograph? What evidence is there to support the link with size of posterior malleolus fracture and method of management of the fracture.
“The rule of a third or percentage is an approximation of the distal tibial articular surface involved in a posterior malleolar fracture, as gauged from a lateral radiograph. Nevertheless, as early as 1971, Mandell observed that superimposition between tibia and fibula could mask posterior malleolar fractures.”
The rule of a third
The rule of a third (or 25% by some authors) was first described in the historic paper by Nelson and Jenson in 19405. They described involvement of at least a third of the posterior tibial articular surface as a, “classical trimalleolar fracture” requiring early open reduction. They reported lesser involvement
