Persistent postoperative step-off of the posterior malleolus leads to higher incidence of post-traumatic osteoarthritis in trimalleolar fractures

Abstract

Background Traditionally, size of the posterior fragment is considered the most important indicator for fixation in trimalleolar fractures. It remains unclear which factors contribute to worse functional and radiological outcome. This study was designed to determine predictors for the development of posttraumatic osteoarthritis and worse functional outcome in trimalleolar fractures. Methods This retrospective cohort study evaluated outcomes of 169 patients with a trimalleolar fracture treated between 1996 and 2013 in a level-1 trauma hospital in the Netherlands after a mean follow-up of 6.3 (range 2.4 to 15.9) years. The average fragment size was 17%. Twenty patients had a posterior fragment smaller than 5% of the intra-articular surface, 119 patients a fragment of 5–25% and 30 patients a posterior fragment larger than 25%. In total, 39 patients (23%) underwent fixation of the posterior fragment. Results Clinical union was achieved in all 169 patients. The median AOFAS score after follow-up was 93 (interquartile range 76–100) and the median AAOS score was 92 (interquartile range 81–98). A persistent postoperative step-off larger than 1 mm was found in 65 patients (39%) and osteoarthritis was present in 49 patients (30%). Higher age and postoperative step-off > 1 mm were independent, significant risk factors for the development of osteoarthritis. Osteoarthritis and BMI were independent, significant risk factors for worse functional outcome. Conclusion It is advisable to correct intra-articular step-off of intraarticular posterior malleolar fragments to reduce the risk of developing osteoarthritis and, consequently, the risk of worse functional outcome after long-term follow-up. Level of evidence Level IIB.

Screw Fixation of the Posterior Malleolus Fragment in Ankle Fracture

“…Failure to restore congruity of the articular surface within 2 mm, including the posterior malleolus, is associated with worse functional outcomes at 1 year compared with patients whose congruity is restored. 1,33 A significant incidence of radiographic arthritis occurs with step-offs of >2 mm at the posterior malleolus, regardless of fragment size. 3 Congruity with stability and degree of reduction may be important prognostic factors, along with joint surface involvement.…”

Comparison of the efficacy of posterior-anterior screws, anterior-posterior screws and a posterior-anterior plate in the fixation of posterior malleolar fractures with a fragment size of ≥ 15 and < 15%

“…Langenhuijsen et al [7] emphasized the importance of the quality of the posterior malleolus reduction, and advocated that the joint congruity, not the fragment size, is the main factor determining the need for fracture fixation. Verhage et al [29] suggested to correct intra-articular step-off of intraarticular posterior malleolar fragments to reduce the risk of developing osteoarthritis. Tosun et al [30] showed that the fixation of PMF is closely related to the successful radiological and functional outcomes of trimalleolar fracture.…”

Traditional Approach vs Posterior Approach for Ankle Fractures Involving the Posterior Malleolus

“…Some authors suggest that clinical outcome is related to fracture displacement, articular surface congruency, and residual tibiotalar subluxation, rather than PMF size. 39 , 45 , 48 Several studies, 11 , 53 , 56 including a review from 2018 by Verhage et al, 52 argue that postoperative step-off is the most important factor predicting posttraumatic osteoarthritis. The current study showed a surprising trend toward more osteoarthritis in group A ( P = .06).…”