How well do we reduce ankle fractures intra-operatively: A retrospective 1 year review using Pettrone's criteria
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Introduction: Ankle fractures are a common injury and considered to be part of the ‘bread & butter’ of orthopaedic trauma surgery. The management of these injuries forms part of the AO Principles course, which is mandatory for application for a specialty training number in trauma & orthopaedics. It has also been used for the technical skills assessment for the national selection process for England. The implication is that ankle fracture fixation is an easy procedure and well within the competencies of all trauma & orthopaedic surgeons. Previous studies demonstrate that most cases of osteoarthritis of the ankle (78%) are post-traumatic in nature (1). Further analysis of this group of patients demonstrates that 48% of patients with post-traumatic ankle arthritis had malleolar fractures. This equates to 37.4% of all patients presenting with ankle arthritis having had a ‘simple’ ankle fracture in the past which as previously mentioned is assumed to be well within the competencies of orthopaedic surgeons to fix. (1) Our study was inspired by an abstract from the BOFAS annual meeting proceedings from University Hospital Aintree (UHA) (2). Using Pettrone’s criteria, they found a 32.5% mal-reduction rate in their study group of ankle fractures, which required open reduction internal fixation. (2,3)
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Methods & Materials: We designed a Google form based data collection tool in order to be able to collect data on a mobile device whilst using a hospital PC to assess the radiographs. In order to maintain patient confidentiality a master Microsoft Excel (Version 14.6.7) spread sheet was made and kept on a hospital computer and each patient assigned a number for use in online data collection. The Hospital’s trauma database was used to identify all ankle fractures admitted within a 1-year period. We collected data on: patient demographics, Lauge-Hansen classification(3,4)of the injury, Level of primary surgeon, type of fixation, satisfaction at last clinic appointment, Pettrone’s criteria (detailed below) (5) The only exclusion fracture was paediatric ankle fractures defined as those who had not reached skeletal maturity at the time of injury. Pettrone’s criteria is based upon the anatomical landmarks shown in the figure below. Figure 1: Medial Malleolus: Satisfactory reduction classed as <1mm step in the articular surface on an AP radiograph Figure 2: Lateral Malleolus (AP): Satisfactory reduction classed as <2mm step in the articular surface on an AP radiograph Figure 3: Lateral Malleolus (lateral): Satisfactory reduction classed as <2mm step in the articular surface on a lateral radiograph Figure 4: Deltoid ligament competence is assessed in Pettrone’s criteria using <3mm clearspace on mortise view – those with >3mm medial clearspace are deemed to have an incompetent deltoid ligament with subsequent talar shift. This measurement was corroborated using Bemuer’s criteria to assess if the medial clearspace was greater then the superior clearspace due to unknown magnification on xrays (7,8) Figure 5: The tibio-fibula overlap should be >1mm on mortise view, if there is syndesmotic injury as the tibia and fibula splay apart there becomes less overlap and in severe injuries no overlap at all. Figure 6: