Slideshow
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Figure 1. Anteroposterior radiograph of the left ankle showing a subtle nondisplaced fracture of the posterior malleolus.
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Figure 2. Lateral view of the ankle.
A 36-year-old man presents with right ankle pain from a fall earlier in the day. The pain prevents him from bearing weight on the ankle. On physical examination, the patient has mild swelling at the medial and lateral ankle. He has tenderness to palpation at the anterior and posterior ankle joint. Radiography of the ankle shows a subtle nondisplaced fracture of the posterior malleolus (Figures 1 and 2).
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Most posterior malleolar fractures occur in the setting of other fractures such as the trimalleolar fracture pattern (lateral, medial, and posterior malleolus fractures).1 Isolated posterior malleolar fractures (as with this case) are far less common and are easy to miss.2 The importance of an intact posterior malleolus is to maintain a congruent joint line and provide stability to the ankle joint.1
Radiography (anteroposterior, lateral, and mortise view) should be performed initially to determine the fracture pattern and look for evidence of a syndesmotic injury. A computed tomography (CT) scan is recommended for all posterior malleolar fractures to check for joint space congruity and lateralization of the talus.1,2 For isolated, nondisplaced posterior malleolar fractures, nonoperative treatment with a nonweight-bearing boot or cast is recommended.1,2
There is no clear consensus on indications for operative treatment. However, in general, a fracture involving more than 25% to 33% of the articular surface and a greater than 2 mm articular step-off are indications for open reduction and internal fixation.1-3
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
References
1. Irwin TA, Lien J, Kadakia AR. Posterior malleolus fracture. J Am Acad Orthop Surg. 2013;21(1):32-40. doi:10.5435/JAAOS-21-01-32
2. Smeeing DPJ, Houwert RM, Kruyt MC, Hietbrink F. The isolated posterior malleolar fracture and syndesmotic instability: a case report and review of the literature. Int J Surg Case Rep. 2017;41:360-365. doi:10.1016/j.ijscr.2017.10.062
3. Rammelt S, Bartoníček J. Posterior malleolus fracture: a critical analysis review. JBJS Rev. 2020;8(8):e19.00207. doi:10.2106/JBJS.RVW.19.00207
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