Tibialis Posterior Tendon Entrapment Within Posterior Malleolar Fracture Fragment
Management of posterior malleolus fractures continues to be controversial, with respect to both need for fixation and fixation methods. Fixation methods include an open posterior approach to the ankle as well as percutaneous reduction and fixation with or without arthroscopy for visualization of the articular surface. Plain radiographs are unreliable in identifying fracture pattern and intraoperative reduction, making arthroscopy a valuable adjunct to posterior malleolus fracture management.
In this article, we report a case of tibialis posterior tendon entrapment within a posterior malleolus fracture, as identified by arthroscopy and managed with open reduction. Tibialis posterior tendon entrapment within a posterior malleolus has not been previously reported. Ankle arthroscopy for posterior malleolus fractures provides an opportunity to identify soft-tissue or tendinous entrapment, articular surface reduction, and articular cartilage injuries unlikely to be identified with fluoroscopy alone and should be considered in reduction and fixation of posterior malleolus fractures.
Not all ankle fractures require CT. However, for posterior malleolus fractures thought to require fixation, preoperative CT may help in determining if percutaneous fixation with or without arthroscopic guidance is a feasible treatment option. Ideally, percutaneous reduction can obviate the need for a larger posterolateral incision and buttress plate and, with arthroscopic assistance, may be superior to indirect reduction with fluoroscopy.
In our patient’s case, arthroscopic assistance facilitated diagnosis of an entrapped structure that would have been difficult to identify, particularly without preoperative CT. It may be difficult to identify imperfect reduction of the posterior malleolus on plain radiographs alone, and arthroscopy-assisted fixation enhances the surgeon’s ability to consider reduction, view incarcerated structures within the joint, and treat articular injuries. We do not routinely use ankle arthroscopy as an adjunct to ankle fracture fixation, but judicious use in select cases can facilitate treatment of intra-articular injuries and facilitate visualization and reduction of posterior malleolar fracture fragments before percutaneous anterior-to-posterior cannulated screw fixation. If an open incision is required, as in the present case, visualization becomes difficult secondary to fluid extravasation. However, we think avoiding the morbidity associated with an open incision is worthwhile for fixation of posterior malleolus fractures.
Conclusion
Close inspection of both preoperative and intraoperative radiographs is required to ensure adequate reduction of a posterior malleolar fragment without soft-tissue or bony interposition in the reduction of ankle fractures. Although not previously reported, posterior tendon entrapment within the posterior malleolus fracture may occur and may require arthroscopic or open techniques to ensure adequate extrication of the tendon to allow for posterior malleolar fracture reduction and fixation. This case report highlights one indication for arthroscopy in the treatment of ankle fractures despite the fact that the tibialis posterior tendon was openly removed. Arthroscopic assistance in acute ankle injuries allows the surgeon to evaluate articular cartilage injuries and ensure there are no interposed structures while checking reduction of the posterior malleolar fracture fragment when present.
