Risk Factors for Stiffness After Fixation of Tibial Tubercle Fractures: A Multicenter Study From the TITUS Group.

Background: Persistent stiffness after operative treatment of tibial tubercle fractures (TTFs) can inhibit functional recovery and interfere with activities of daily living. Given the rare nature of this fracture, little data exist to help identify risk factors for this complication. The purpose of this multicenter study was to identify risk factors for stiffness after fixation of TTFs. Methods: Operatively managed TTFs at 7 tertiary children's hospitals in patients younger than 18 years were included in this retrospective comparative study. Fractures with <3 months of documented postoperative range of motion and those fixed with nonscrew implants were excluded. Demographic, clinical, and radiographic data were reviewed. Persistent stiffness was defined as lacking ≥20° of flexion compared with the contralateral knee at 3 months after surgery. Univariable analysis was followed by multivariate regression to adjust for confounders. Results: The incidence of prolonged stiffness among the 369 included patients was 3.0%. The median time between initial presentation and surgery was longer in those who developed stiffness (24 versus 14 hours, p = 0.002). Furthermore, those who had surgery >24 hours after presentation developed stiffness more often than those who underwent fixation within 24 hours (12.7% versus 1.6%, p < 0.001). The median duration of postoperative immobilization was longer in patients who developed stiffness (45 versus 28 days, p = 0.006). Children immobilized >4 weeks after surgery developed stiffness more frequently than those who initiated mobilization within 4 weeks (5.7% versus 0.6%, p = 0.009). When adjusting for confounders such as age and fracture classification, fixation >24 hours after presentation was associated with 9.7 times higher odds of stiffness (95% CI 2.0-46.5, p = 0.004) and postoperative immobilization >4 weeks had 10.3 times higher odds of stiffness (95% CI 1.1-95.0, p = 0.04). Conclusions: Persistent stiffness after surgical fixation of TTFs occurs in 3.0% of children. Prolonged postoperative immobilization (>4 weeks) and delayed surgical fixation (>24 hours) are associated with higher odds of a persistent flexion deficit 3 months after surgery. Surgeons should consider this information when determining timing of treatment and postoperative protocols. Level of Evidence: Level III, retrospective comparative study. See Instructions for Authors for a complete description of levels of evidence.