The Tibiofibular Line: A Reliable Method of Syndesmosis Assessment in Certain Fibula Morphologies

Background The tibiofibular line (TFL) technique was initially proposed to assess syndesmosis reduction. Clinical utility was limited by low observer reliability when applied to all fibulas. This study aimed to refine this technique by describing TFL's applicability to various fibula morphologies. Methods Three observers reviewed 52 ankle CT scans. Observer consistencies for TFL measurement, anterolateral fibula contact length, and fibula morphology were assessed using intraclass correlation (ICC) and Fleiss' Kappa. Results TFL measurement and fibula contact length intra-observer and inter-observer consistencies were excellent (minimum ICC, 0.87). Fibula shape categorization intra-observer consistency was substantial to almost perfect (Fleiss' Kappa, 0.73 to 0.97). Six to 10 mm of fibula contact length corresponded to excellent TFL distance consistency (ICC, 0.80 to 0.98). Conclusion The TFL technique appears best for patients with 6 mm to 10 mm of straight anterolateral fibula. Sixty-one percent (61%) of fibulas featured this morphology, indicating most patients may be amenable to this technique.