O2139: Risk Factors for Stiffness After Fixation of Tibial Tubercle Fractures: A Multicenter Study

Background: Prolonged stiffness after surgical fixation of tibial tubercle fractures can delay return to activity and may potentially require operative intervention. Given the relatively uncommon nature of this fracture, there is little data on which patients may be at risk for this complication. The purpose of this study is to identify risk factors for prolonged stiffness after surgical fixation of tibial tubercle fractures.

Methods: This retrospective comparative study included patients younger than 18 years that underwent surgical fixation of a tibial tubercle fracture at seven tertiary children’s hospitals. Fractures fixed with implants other than screws were excluded, as were patients with less than 3 months of documented range of motion. Demographic, radiographic, and clinical data were reviewed. Prolonged stiffness was defined as lacking 20 or more degrees of flexion compared to the contralateral knee at 3 months after surgery. Univariable analysis was followed by multivariate regression to adjust for confounders.

Results: Of the 369 patients in the study, 3.0% developed prolonged stiffness after surgery. In univariable analysis, the median time between initial presentation and surgery was longer in those that developed stiffness (24 h versus 14 h, p=0.002). Furthermore, 12.7% of those that underwent surgery later than 24 hours after presentation became stiff compared to 1.6% of patients that had surgery within 24 hours (p < 0.001). The median time of post-operative immobilization was longer in patients that developed stiffness (45 d versus 28 d, p=0.006). Children that were immobilized longer than 4 weeks became stiff more frequently than those that were mobilized within the first 4 weeks (5.7% versus 0.6%, p=0.009). When adjusting for confounders, including age and fracture classification, fracture fixation later than 24 hours after presentation was associated with 9.7 times higher odds of stiffness (95% CI 2.0-46.5, p=0.004). Post-operative immobilization greater than 4 weeks was associated with 10.3 times higher odds of this complication (95% CI 1.1-95.0, p=0.04).

Conclusion: Post-operative stiffness occurs in 3.0% of patients that undergo fixation of a tibial tubercle fracture. Surgical delay and prolonged post-operative immobilization are associated with substantial flexion deficits at 3 months after surgery. Surgeons should consider this information when determining timing of treatment and post-operative protocols.