SLR - January 2020 - Megan A. Ishibashi
Reference: Kellam PJ, Haller JM, Rothberg DL, Higgins TF, Marchand LS. Posterior Malleolar Fracture Morphology in Tibial Shaft Versus Rotational Ankle Fractures: The Significance of the Computed Tomography Scan J Orthop Trauma. 2019 December, 33(12), 459-465.Scientific Literature Review
Reviewed By: Megan A. Ishibashi, DPM
Residency Program: Kaiser SF Bay Area Foot and Ankle Surgery – Oakland, CA
Podiatric Relevance: The size of the posterior malleolar fragment has been widely studied in regards to the importance for posterior talar stability, rotational ankle stability and tibiotalar load transfer. Studies have demonstrated that ankle fractures with posterior malleolus involvement lead to worse clinical outcomes compared to those without posterior malleolar involvement. The management of posterior malleolus fractures remains controversial with no clear consensus regarding the indications for fixation. Fragment size is typically discussed as one of the main indications for fixation however, there are varying results regarding the correlation between clinical outcomes and fragment size. The current practice dogma has recently shifted towards posterior malleolar fracture morphology rather than fragment size. Morphology of posterior malleolus fractures differ within rotational ankle injuries and have also been found to have an association with tibial shaft fractures. The overall purpose of this study was to compare the morphology of posterior malleolar fractures in ankle fractures versus tibial shaft fractures.
Methods: The authors retrospectively reviewed 54 patients with tibial shaft fractures and 61 patients with ankle fractures between January 2012 and December 2017. Patients were excluded if the posterior malleolus was a part of an axial pilon fracture, if there were insufficient anteroposterior or lateral radiographs or those without computer tomography (CT) imaging. Measurements were obtained on the lateral view radiograph and sagittal and axial CT cuts.
Results: Posterior malleolar fractures were significantly larger when associated with tibial shaft fractures compared to ankle fractures, 32 percent vs 15 percent cross sectional area, respectively. This study identified a unique fracture pattern in Type II Haraguchi fractures associated with tibial shaft fractures - an additional fracture line oriented in the sagittal plane. The authors found that 93 percent of posterior malleolar fractures associated with tibial shaft fractures were surgically fixed compared to 63 percent of posterior malleolar fractures in ankle fractures. Also, fragment displacement was significantly higher in ankle fractures compared to tibial shaft fractures, 96 percent versus 56 percent, respectively.
Conclusions: Posterior malleolar fractures that occur with tibial shaft fractures are more than twice as large as those associated with rotational ankle fractures. The morphology of these fractures also include a special subset specific to posterior malleolus fractures associated with tibial shaft fractures. This study also highlights the importance of CT scans to identify the presence of posterior malleolus fractures since these fractures are often missed on plain radiographs. The fracture fragment may appear nondisplaced on radiographs however, evaluating the intra-articular extension is important as previous studies have found that posteromedial extension (Type II) may have worse clinical outcomes if not addressed.