SLR - May 2015 - Zeno Pfau

Anatomy and Classification of the Posterior Tibial Fragment in Ankle Fractures

Reference: :  Bartoníček J, Rammelt S, Kostlivý K, Vaněček V, Klika D, Trešl I. Anatomy and Classification of the Posterior Tibial Fragment in Ankle Fractures. Arch Orthop Trauma Surg. 2015 Apr;135(4):505-16.

Scientific Literature Review

Reviewed By: Zeno Pfau, DPM
Residency Program: North Colorado Podiatric Medicine and Surgery Residency, Greeley, CO

Podiatric Relevance: Ankle fractures are common injuries with an incidence of approximately 187 fractures per 100,000 people each year. Posterior malleolar fractures occur from impact of the talus on the tibia with an external rotation or pronation force. These fractures rarely occur in isolation and as such the presence of them is a poor prognostic factor. So far, no generally accepted, clinically relevant classification of these injuries exist. This is a large cohort study with the primary goal of developing a classification for posterior fragments with pathoanatomy obtained via comprehensive CT examination.
 
Methods: One hundred and forty one consecutive individuals with a Weber B or C type pattern with evidence of posterior tibial fragment in standard radiographs were included in the study.  Patients presented from January 2012 to December 2013. All patients received post-injury radiographs in A/P, mortise and lateral views. All patients underwent CT scanning with reconstruction in transverse, sagittal, and frontal planes. Three-dimensional CTs were used to evaluate the shape and size of the posterior tibial fragment by the two senior authors. The posterior rim of the tibia was divided into the following parts: posterior tibial tubercle, posterior rim, malleolar groove, posterior colliculus. Another aspect of the evaluation was extension of the fracture into the fibular notch.

Results: Of the 141 cases, 137 cases were able to be divided into one of four types with constant pathoanatomic features. The remaining four cases were placed into a Type 5 fragment pattern.
Type 1: Extraincisural fragment, was recorded in 8 percent of patients. Result from avulsion of attachment of posterior tibifibular ligament or of intermalleolar ligament
Type 2: Posterolateral fragment, was recorded in 52 percent of patients. Involved one-quarter to one-third of fibular notch
Type 3: Posteromedial two-part fragment, was recorded in 28 percent of patients. Involved medial malleolus
Type 4: Large posterolateral triangular fragment, was recorded in 9 percent
Type 5: Irregular osteoporotic fracture, was recorded in 3 percent. Comminution of fragments present caused most probably by osteoporosis.

Conclusion: Prior studies have shown the difficulty in assessing the shape and size of the posterior malleolar fragment on the basis of plain radiographs. Accordingly, trying to develop a classification utilizing plain radiographs would also prove to be difficult and unreliable. The study was able to provide a classification for posterior malleolar fragments that allowed 137 cases to be divided into one of four types based on pathoanatomic features gathered from CT scanning. With future research, it may be useful in developing indication for surgeries to these injuries.  

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