• Hwee Weng Dennis Hey, Li Wen Nathaniel Ng, Yau Hong Ng, Wei Zhong Jonathan Sng, Ruben Manohara, and Joseph Shanthakumar Thambiah.
• Department of Orthopaedic Surgery National University Health System, Singapore. Electronic address: dennis_hey@nuhs.edu.sg.
• Injury. 2016 Jun 1; 47 (6): 1276-81.

BackgroundProximal tibiofibular joint (PTFJ) injuries are not uncommon but relatively understudied. This study evaluates the effectiveness of 2 radiographic methods in assessing the integrity of the PTFJ.Study DesignThis is a cross-sectional study of 2984 consecutive patients with knee X-rays done in a single institution over a 4-month period. A total of 5968 knee X-rays were assessed using 2 methods-[1] The direction in which the fibula points to in relation to the lateral femoral epicondyle on anteroposterior view and Blumensaat line on lateral view. [2] The degree of tibiofibular overlap as percentage of widest portion of the fibula head. Sensitivity and specificity of these methods in diagnosing a disrupted PTFJ are calculated. Variables including quality of X-rays, weight-bearing status of AP views and degree of knee flexion on lateral views are also recorded. Univariate analysis was carried out to investigate the association between variables using chi-square test for nominal data and student t-test for continuous data.ResultsThe fibular points towards the lateral femoral epicondyle on AP view in 94.4% of the patients and points towards the posterior half of the Blumensaat line on lateral view in 98.1% of the patients. Using this method, weight-bearing X-rays are significantly associated with the direction the fibula is pointing (p<0.01) on the AP view and the degree of knee flexion is associated with the direction the fibula is pointing (p<0.01) on the lateral view. The AP tibiofibular overlap ranges from >0% to <75% in 94.1% of the patients and the lateral tibiofibular overlap ranges from >0% to <75% in 84.5% of the patients. This method is associated with whether true orthogonal X-rays of the knees are taken (p=0.048).ConclusionThe direction in which the fibula is pointing and the percentage of tibiofibular overlap are highly specific radiographic methods useful in defining the PTFJ. The first method requires a weight-bearing view on AP assessment and >20 degrees of flexion on lateral assessment. True orthogonal AP and lateral views are required for the second method to be used.Copyright © 2016 Elsevier Ltd. All rights reserved.

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