High Rates of Subjective Instability Following Tibial Plateau Fractures: Results of a Multicenter Study

Objectives: Tibial plateau fractures (TPF) are increasingly regarded as complex knee joint injuries rather than isolated fractures. However, standardized recommendations for the diagnosis and management of concomitant soft-tissue injuries are still lacking. Post-traumatic instability has a significant impact on both clinical outcomes and the development of post-traumatic osteoarthritis. The present study was therefore designed to analyze the rate of subjective instability and its potential causes following TPF in a large, multicenter patient cohort. Methods: This multicentric, retrospective study included patients who underwent surgical treatment for TPF between 2011 and 2021. Fractures were classified according to the Schatzker and ten-segment classification. Trauma mechanisms and treatment strategies as well as pre- and postoperative imaging were analyzed. Patient-reported outcome measures (PROMs) were collected using standardized questionnaires (KOOS, Lysholm, Tegner, IKDC). Subjective instability was defined as a positive response to an instability-related question in those questionnaires. Statistical analysis was performed using t-tests and chi-squared tests. Results: A total of 348 patients were included in the study. The mean age was 51 years (standard deviation ±14.3 years); 61% were female and 39% male. Preoperative MRI was performed in 22.5% of cases. Surgical treatment of concomitant soft-tissue injuries (meniscal repair or ligament reconstruction) was performed in 18% of cases. Overall, 42% (n = 146) of patients reported subjective instability. No significant difference was found between Schatzker type I–III and Schatzker type IV–VI fractures. Concerning the ten-segment classification, the postero-medio-central and antero-medio-medial segments were most frequently associated with instability (53% and 52%, respectively). Postoperative tibial slope and medial proximal tibial angle (MPTA) did not differ significantly between stable and unstable groups 6 weeks postoperatively. Concomitant collateral ligament injuries were associated with an increased rate of postoperative instability. Significant patient-related risk factors for postoperative instability included younger age (p = 0.007), higher BMI (p = 0.001), and active nicotine abuse (p = 0.008). Conclusion: This study demonstrates a high rate of subjective instability following tibial plateau fractures. These instabilities cannot be sufficiently explained by the initial bony fracture complexity or postoperative bone deformity alone. Therefore, the diagnosis and management of concomitant soft-tissue injuries in TPF should be further investigated.