Summary
This study investigated the relationship between postoperative pain and functional as well as psychological outcomes at 6 months following ACL reconstruction using a quadriceps tendon autograft. Patients who experienced pain exhibited lower psychological readiness and subjective knee function, suggesting the need for preoperative psychological assessment and tailored rehabilitation.
Abstract
Background
Persistent pain after anterior cruciate ligament reconstruction (ACLR) is known to negatively influence functional recovery and psychological readiness, which are critical determinants of return to sport. While the quadriceps tendon (QT) autograft is increasingly adopted due to favorable graft characteristics and low donor site morbidity, limited evidence exists regarding the association between postoperative pain and other recovery-related domains following QT-ACLR. Understanding this relationship may support improved rehabilitation strategies and patient outcomes.
Purpose
To evaluate the relationship between postoperative pain, knee joint function, and psychological factors at 6 months after ACL reconstruction using a quadriceps tendon autograft.
Methods
This prospective observational study included 59 patients (mean age: 27.0 ± 12.6 years; 30 males, 29 females) who underwent primary ACLR using a QT autograft at a single institution between 2021 and 2023. All participants completed standardized rehabilitation protocols and underwent preoperative, 3-month, and 6-month postoperative assessments. Functional evaluations included isokinetic quadriceps strength measured at 60°/s, heel height difference (HHD), heel-buttock distance (HBD), and the International Knee Documentation Committee (IKDC) subjective knee score. Psychological readiness was assessed using the ACL–Return to Sport after Injury (ACL-RSI) scale. Pain during quadriceps strength testing was recorded using an 11-point Numerical Rating Scale (NRS). At the 6-month timepoint, patients were divided into two groups based on the presence of pain: the NP group (NRS = 0, no pain) and the P group (NRS = 1, pain present).
Results
Twenty-nine patients were classified in the NP group and 30 in the P group. The P group reported significantly greater pain during quadriceps strength testing at 3 months (mean NRS 3.4 vs 1.9, P < 0.01), despite no differences in preoperative NRS values. Additionally, the P group demonstrated significantly lower ACL-RSI scores preoperatively (mean 52.4 vs 66.5, P < 0.05), at 3 months (P < 0.01), and at 6 months (P < 0.01). IKDC subjective scores were also significantly lower in the P group at 3 months (P < 0.01), while no significant group differences were observed in quadriceps strength, HHD, or HBD at the 6-month evaluation.
Conclusion
Patients who experienced pain during quadriceps testing at 6 months following QT-ACLR demonstrated consistently lower subjective knee function and reduced psychological readiness throughout the recovery period. Notably, these individuals also exhibited lower ACL-RSI scores even prior to surgery, suggesting that preoperative psychological state may contribute to postoperative pain perception and rehabilitation response. These findings highlight the importance of integrating psychological screening and support into ACLR care pathways. Clinicians should consider early identification of individuals with lower ACL-RSI scores to guide individualized, multidimensional rehabilitation strategies aimed at minimizing persistent pain and enhancing recovery and return-to-sport outcomes following QT-ACLR.