Anatomic reductions are rarely achieved for severely displaced pilon fractures and this portends severe osteoarthritis.

PURPOSE: To evaluate the association between initial articular displacement, postoperative residual articular displacement, and the development of severe osteoarthritis in pilon fractures. METHODS: A retrospective review was performed of adults with operative pilon fractures (OTA/AO 43) at a level I trauma center. Three surgeons reviewed injury, postoperative, and follow-up radiographs to grade initial articular displacement as <2 mm, 2-5 mm, or >5 mm, postoperative residual articular displacement as 0 mm, ≤2 mm, or >2 mm, and the osteoarthritis (OA) grade as 0 (none), 1 (doubtful), 2 (minimal), 3 (moderate), and 4 (severe). The associations between initial displacement, residual displacement, and the development of severe OA were evaluated. RESULTS: There were 115 patients with pilon fractures included. Initial articular displacement on injury radiographs was associated with residual articular displacement with 100.0% (28/28) of patients with <2 mm of initial articular displacement having 0 mm of residual articular displacement, compared to 51.7% (15/29) and 17.2% (10/58) of patients with 2-5 mm and >5 mm of initial articular displacement (p<0.0001). The development of grade 4 OA was associated with both initial articular displacement (p<0.0001) and residual articular displacement (p<0.0001). All patients with an initial articular displacement <2 mm achieved anatomic reductions with no cases of grade 4 OA. In contrast, grade 4 OA developed in 66.7% (4/6) and 85.7% (18/21) of patients with an initial articular displacement of 2-5 mm and >5 mm that also had a residual articular displacement of >2 mm. CONCLUSIONS: Severely displaced articular injuries were less likely to receive anatomic reductions and more likely to develop severe OA.