Early surgery, meniscal injury and physiologic contralateral knee extension deficit are associated with extension loss prior to anterior cruciate ligament reconstruction

PURPOSE: To identify factors associated with knee extension loss prior to anterior cruciate ligament (ACL) reconstruction (ACLR). METHODS: Patients without concomitant ligament injuries who underwent primary ACLR at the Capio Artro Clinic, Stockholm, Sweden, between 1 January 2002 and 31 December 2023, were eligible for inclusion. The outcome of the study was the presence of preoperative extension loss, defined as a deficit of ≥5 degrees prior to ACLR. Univariable and multivariable logistic regression analyses were conducted to assess associations between the study outcome and the following variables: age at surgery, sex, time from injury to surgery, preinjury Tegner activity level, cartilage injury, medial meniscus or lateral meniscus injury, and physiologic contralateral knee extension deficit (≥5 degrees). RESULTS: A total of 10,692 patients were included. The overall incidence of extension loss prior to ACLR was 6.3% (677/10,692). Multivariable logistic regression analysis showed that early surgery (≤3 months) (odds ratio [OR]: 2.94; 95% confidence interval [CI]: 2.43-3.57; p < 0.001), medial meniscus injury (OR: 1.30; 95% CI: 1.07-1.57; p = 0.01), lateral meniscus injury (OR: 1.23; 95% CI: 1.01-1.48; p = 0.04) and physiologic contralateral knee extension deficit (OR: 34.38; 95% CI: 25.36-46.61; p < 0.001) were associated with increased odds of extension loss prior to ACLR. No associations were found between preoperative extension loss and age at surgery, sex, preinjury Tegner activity level, or the presence of a cartilage injury. CONCLUSIONS: Preoperative extension loss was observed in 6.3% of the patients undergoing ACLR. Early surgery (≤3 months), medial or lateral meniscal injury, and physiologic contralateral knee extension deficit were associated with increased odds of preoperative extension loss. Awareness of these factors may assist clinicians identify patients at risk for extension loss and optimise preoperative management strategies prior to ACLR. LEVEL OF EVIDENCE: Level III.