Factors affecting anterior knee pain following anatomic double-bundle anterior cruciate ligament reconstruction

Purpose: The purpose of this study was to evaluate the prevalence of anterior knee pain in anatomic double-bundle anterior cruciate ligament (ACL) reconstruction and to identify critical factors affecting postoperative anterior knee pain development. Methods: Subjects comprised 171 patients (171 knees) who underwent anatomic double-bundle ACL reconstruction with a follow-up period of ≥2 years. The procedure used bone-patellar tendon-bone plus gracilis tendon (BTB-G) in 56 knees, semitendinosus tendon (ST) in 71 knees, and ST-G in 44 knees. Clinical results and prevalence and severity of anterior knee pain were assessed at 3 months and 2 years postoperatively. Clinical variables influencing anterior knee pain development at each postoperative period were subjected to univariate analysis, followed by logistic regression analysis to identify risk factors for anterior knee pain. Results: Overall prevalences of anterior knee pain at 3 months and 2 years postoperatively were 42. 0 and 11. 1%, respectively. Use of BTB-G graft represented the highest prevalence of anterior knee pain between the 3 different grafts (P = 0. 001); however, this statistical significance disappeared at 2 years postoperatively. Prevalence of postoperative extension deficit was significantly higher in anterior knee pain-positive cohort than in anterior knee pain-negative cohort at 3 months postoperatively. Level of quadriceps strength was significantly lower, and Lysholm score was significantly worse in anterior knee pain-positive cohort than in anterior knee pain-negative cohort at 2 years postoperatively. According to logistic regression analysis, knee extension deficit was a predisposing factor for the development of anterior knee pain at 3 months postoperatively (odds ratio, 2. 76; P = 0. 004); however, there was no significant predisposing factor for anterior knee pain at 2 years postoperatively. Conclusions: Knee extension deficit was an important predisposing factor for postoperative anterior knee pain in the early postoperative period, and anterior knee pain was associated with impaired quadriceps function and inferior subjective results over 2 years postoperatively. Early recovery of full extension may prevent postoperative development of anterior knee pain and achieve successful outcomes for ACL reconstruction. Level of evidence: Retrospective comparative study, Level III.