Abstract
Objectives:
To identify predictive factors for successful return to sport (RTS) following anterior cruciate ligament reconstruction (ACL-R) with quadriceps tendon (QT) autograft.
Methods:
Data was retrospectively collected on consecutive patients who underwent ACL-R with QT autograft at a single institution between 2010-2020. Patient demographics, knee range of motion (ROM), injury characteristics, and intraoperative data were collected from the electronic medical record. Full RTS was defined as the patient returning to their prior level of sport and the presence of a clinical documentation of no further complications. Univariate and multivariate cox regression were utilized to conduct time-to-event analyses to identify predictors of early RTS clearance by surgeon. Additionally, both logistic regression analysis and generalized estimating equations were used to identify significant predictors of successful full RTS. STATA 16SE software was utilized for all analyses with statistical significance set to p < 0.05.
Results:
A total of 307 patients were included, consisting of 176 males (57.3%) and 131 females (42.7%), with an average of 20.7 ± 7.1 years of age and 14.5 ± 8.9 months follow-up. Ten patients (3.3%) were professional/semi-professional athletes, 38 (12.4%) were collegiate athletes, 144 (46.9%) were high school athletes (46.9%), and 115 (37.5%) were recreational athletes. Complete knee extension was achieved by 64.1% of patients at 6 weeks postoperatively, by 77.7% at 3 months, by 84.4% at 6 months, and by 84.7% at 1 year. Full knee extension at 3 (HR: 1.55, 95% CI: 1.13–2.12, p = 0.007) and 6 months (HR: 1.49, 95% CI: 1.05–2.12, p = 0.025) postoperatively were predictors of a higher rate of RTS clearance. Moreover, patients who achieved full knee extension at 3 months follow-up had a greater rate of RTS (1.02/person-years) compared to patients who did not achieve full knee extension at 3 months (0.83 per person-years). When considering RTS, only full knee extension at 4-6 weeks (OR:2.02, 95% CI:1.02–4.03, p = 0.045) and at 3 months (OR:2.36, 95% CI: 1.12–4.99, p = 0.024) postoperatively were predictive of successful RTS. No other significant predictors were identified.
Conclusions:
Restoration of full knee extension was strongly associated with higher rates of both surgeon clearance and successful RTS. The role of full knee extension in the ability to regain strength at 6 months, as measured by limb symmetry indices, after ACL-R has been previously described. While both ROM and strength play crucial roles in the rehabilitation process, achieving full ROM typically precedes restoration of full strength. Lack of full extension 3 months postoperatively may require further investigation and serves as a possible opportunity for a goal metric to maximize RTS rates and minimize complications after ACL-R.