SLR - August 2014 - Nazia Shah

Missed Isolated Posterior Malleolar Fractures
Reference: Ozler T, Guven M, Onal A, Ulucay C, Beyzadeoglu T, Altintas F. Missed Isolated Posterior Malleolar Fractures. Acta Orthop Traumatol Turc. 2014; 48(3): 249-52. 
Scientific Literature Review
Reviewed By: Nazia Shah, DPM
Residency Program: Hoboken University Medical Hospital
Podiatric Relevance: Fourteen percent to 44 percent of all ankle fractures contain posterior malleolar fractures, but isolated posterior malleolar fractures comprise a total of only 1 percent of all ankle fractures. Posterior malleolar fracture fragments involving < 25 percent articular surface traditionally need not be fixated. Larger fractures that involve greater than 25% articular surface should be fixed to avoid instability and degenerative changes. Patients with isolated posterior malleolar fractures usually have non-specific complaints of an ordinary ankle sprain and symptoms will not correlate with the Ottawa Ankle Rules (OAR). Furthermore, posterior malleolar fractures may be difficult to diagnose with the standard radiograph views typically taken for an ankle sprain/fracture.  This study was designed to evaluate injury mechanism, clinical and radiological results of patients with missed isolated posterior malleolar fractures.
Methods: Between the years of 2007 and 2011, 846 patients presented to the hospital with an ankle sprain. All patients were examined with OAR guidelines. Four hundred and twenty patients were also examined with the three standard x-rays (AP, lateral and MO). Fifty-two patients had lateral malleolar fractures, 16 patients had bimalleolar fractures, nine patients had trimalleolar fractures, and six patients had isolated syndesmotic diastasis. Three hundred thirty-seven patients did not present with fractures, dislocation or syndesmotic diastasis. Treatment for these patients was cold application, compressive bandages, and NSAIDs with limited weight bearing.  At the third week follow up, 13 patients had persistent symptoms. These patients then underwent MRI studies followed by a 50 degree external rotation lateral ankle view. In seven patients, an isolated posterolateral-oblique posterior malleolor fracture was noted; three patients presented with bone marrow edema at the tibial plafond, and three patients presented with total talofibular ligament tear. All patients were treated with an ankle brace and non-weight bearing for three weeks until fracture healing. All patients were followed up for one year.
Results: Only one patient who was diagnosed with an isolated posterior malleolar fracture had pain after three-month-follow up. This patient did not have evidence of bone healing up to six months. There was no surgical intervention for this patient. At one year, there was no instability or degenerative changes in all seven patients who were diagnosed with a posterior malleolar fracture.
Conclusions: Isolated posterior malleolar fractures may mimic simple ankle sprains. OAR is ineffective in diagnosing isolated posterior malleolar fractures. However, 50 degree external rotation lateral radiograph has demonstrated to be more effective in diagnosing posterior malleolar fractures. These fractures may be missed on standard radiographs due to the small size of the posterior malleolous fracture and the overlap of the distal fibula. It is demonstrated in this case study series that conservative treatment of such fractures is successful clinically and radiologically. Always keep isolated posterior malleolar fractures in mind if patient presents with a forced plantar flexion type injury or axial compression injury with pain at the posterior ankle.

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