Joos D

Posterior pilon fractures: a retrospective case series and proposed classification system.

Background: Posterior malleolus fractures occur in 7% to 44% of ankle fractures and are associated with worse clinical outcomes. Fractures that involve the posteromedial plafond extending to the medial malleolus have been described previously in small case series. Failure to identify this fracture pattern has led to poor clinical outcomes and persistent talar subluxation. The purpose of this study was to report our outcomes following fixation of this posterior pilon fracture and to describe a novel classification system to help guide operative planning and fixation. Methods: Eleven patients were identified following fixation of a posterior pilon fracture over a 4-year span; 7 returned at minimum 1-year follow-up to complete a physical examination, radiographs, and RAND-36 (health-related quality of life score developed at RAND [Research and Development Corporation] as part of the Medical Outcomes Study) and American Orthopaedic Foot & Ankle Society (AOFAS) ankle/hindfoot questionnaires. Patient records were reviewed to evaluate for secondary complications or operative procedures. Results: Our mean postoperative AOFAS ankle/hindfoot score was 82. Anatomical reduction of the plafond was noted radiographically in 7 of 11 patients, with the remainder demonstrating less than 2 mm of articular incongruity. Five of 7 patients demonstrated ankle and hindfoot range of motion within 5 degrees of the uninvolved extremity. Four complications required operative intervention; 2 patients reported continued pain secondary to development of CRPS. Conclusion: The posterior pilon fracture is a challenging fracture pattern to treat, and it has unique characteristics that require careful attention to operative technique. Our results following fixation of this fracture pattern are comparable with results in the literature. In addition, a novel classification scheme is described to guide recognition and treatment of this fracture pattern. Level of Evidence: Level IV, retrospective case series.

Foot & ankle international.

Thank you very much for your interest and comments on our article published in the February 2013 issue of Foot & Ankle International. We agree that articular impaction is a component of this injury and clearly will negatively affect the function of patients. However, when one is considering this injury pattern, the presence of articular comminution should not play a role in determining the need for fixation. The surgical approach does require addressing the impacted fragments. Primarily, we have noted that articular impaction will preclude indirect reduction of the posterolateral fracture as has been historically described. As described in the article, the fragments are either reduced from a cranial to caudal direction or excised if reduction cannot be achieved. The use of the fracture lines to determine the need for fixation is based on the consideration that joint stability is the critical factor of this injury. Amorosa et al describe fixation for fracture with a minimum of 20% involvement of the posterior plafond. We believe that the size of the fragment does not play a critical role in determining the need for fixation. The importance of anatomic reduction and fixation of the posterolateral and posteromedial fragment to prevent late subluxation with associated degenerative changes is what we have chosen to emphasize. All cases in our series did not have articular impaction as that was not a factor in determining the need for operative intervention. In the experience described by Weber, restoration of joint congruity with an osteotomy resulted in improved clinical outcomes, despite inability to correct articular impaction. Therefore, we believe that it is appropriate to consider posterior plafond fracture without articular comminution a “posterior pilon” to emphasize the importance of the injury and the need to restore joint congruity to minimize arthrosis. This is similar to a traditional pilon fracture that involves the articular surface without articular comminution; the presence of comminution does not alter the need for operative reduction and stabilization to restore joint congruity and minimize arthrosis. Reduction of the involved articular impaction is difficult, as you have described. In this fracture pattern and in our experience, there has not been the need for bone grafting proximal to the articular fragment. The computed tomography scans that we presented in the article are representative of the size of the involved articular fragments in our series and that described by Weber without the presence of a significant bone void following reduction. The use of K-wires to stabilize the fragments is described in the article by Wang et al, as you have referenced. However, in their description, the fragments were reduced indirectly via the posterolateral approach and assessed by fluoroscopy. The secondary posteromedial approach they described was for visualization of reduction of the large posteromedial fragment and fixation and not for assessment of the reduction of the articular fragments. This critique regarding our described technique for reduction applies to their technique as well. This is expected as one cannot directly visualize the reduction given the anatomical structure of the distal tibia. Stabilization of the fragments with a K-wire is an excellent suggestion, although given the small fragment sizes noted in our series, such stabilization may be difficult to achieve. Your described technique would be excellent for larger fragments that are amenable to fixation. The classification system was based on our experience of low-energy injuries that did not involve a known axial loading mechanism, which was not explicitly stated, as you have pointed out. No patient had a fracture pattern in which the posterior colliculus was persistently attached to the anterior colliculus of the medial malleolus. As we continue to collect data on this injury, we may encounter that pattern. In the article by Wang et al, a type II injury is described in 5 patients in whom the posterior malleolus and the anterior aspect were one piece: 3 of these cases were electric bike accidents that would not be considered in our series because this situation imparts a higher energy mechanism. Given the limited number of patients, we may not have encountered this pattern in our specific cohort. This variation exists, as you have stated, and the classification can be modified for our type I patient to state that a single posteromedial fragment is present. This will include the specific variation you describe and would not alter the surgical approach that we describe for type I. Thank you for comments regarding the syndesmotic disruption. We agree that Amorosa et al have described this additional injury and this was not noted in our review of the literature. Our diagnosis of instability, however, is determined by preoperative imaging as opposed to intraoperative determination of instability via fluoroscopy. We do routinely perform intraoperative stress testing; however, are we concerned that with direct stabilization of the posterior lateral malleolus, instability may not be detected via stress testing. Therefore, preoperative 3-D imaging is important to determine disruption of the anterior tibiofibular ligament and interosseus ligament with clear widening of the tibiofibular joint and should be performed when one encounters these injuries, as we now routinely perform following the review of our experience. 487177 FAIXXX10.1177/1071100713487177Foot & Ankle InternationalResponse research-article2013