SLR - August 2019 - Morgan E. Garcia

Morphology of the Posterior Malleolar Fracture Associated with a Spiral Distal Tibia Fracture

Reference: Mitchell PM, Harms KA, Lee AK, Collinge CA. Morphology of the Posterior Malleolar Fracture Associated With a Spiral Distal Tibia Fracture. Journal of Orthopaedic trauma. 2019 Apr 1;33(4):185-8.

Scientific Literature Review

Reviewed By: Morgan E. Garcia, DPM
Residency Program: University of Florida Health – Jacksonville, FL

Podiatric Relevance: Posterior malleolus fractures represent the most common variant extension into the articular surface. Current literature advocates for fixation of the posterior malleolus fracture prior to fixation of distal tibial fractures to reduce the incidence of intraoperative displacement and subsequent malreduction. The objective of this study is to define the pathoanatomy of the posterior malleolus fracture in association with spiral distal tibia fractures in order to guide clamp and implant placement when treating these injuries.  

Methods: This is a retrospective review evaluating 122 spiral infraisthmal tibia fractures which were isolated from a cohort of 922 tibial fractures undergoing intramedullary nailing over a seven year period at a level one trauma center. Preoperative, intraoperative and postoperative imaging were collected and classified to evaluate these fractures for varying degrees of severity and to evaluate for intraarticular extension. For patients whose injuries included a posterior malleolus fracture and had CT imaging performed preoperatively, a fracture map was created using the axial image 2-3 mm above the ankle joint. Angular measurements of the posterior malleolar fracture were taken in reference to the bimalleolar axis for further evaluation of each fracture pattern.

Results: Distal tibial intra-articular involvement occurred commonly in the setting of a spiral infraisthmal tibia fracture (84/122, 69 percent), with posterior malleolus fractures constituting the majority of these cases (59/122, 48 percent). Other fractures included plafond fractures (8/122), medial malleolus fractures (7/122) and anterior fractures (5/122). The most common pattern of posterior malleoli fractures (41/44, 93 percent) were oriented in the posterior lateral-oblique direction, on average 24 degrees from the bimalleolar axis. The remaining three were transverse-medial extension type fractures. Of the fractures identified on a CT scan, 39 percent (17/44) were not visible on preoperative injury radiographs.

Conclusions: The authors found that intraarticular distal tibial fractures occur in most cases of infraisthmal spiral tibia fractures. Posterior malleolus fractures occurred in approximately half of the studied fractures and are consistently posterolateral in nature. The angular measurements calculated in this study can be used to enhance evaluation of the posterior malleolus intraoperatively. External rotation of the ankle approximately 25 degrees allows for an optimal view point for assessing these fractures and could potentially allow surgeons to abandon preoperative CT imaging. 

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