BACKGROUND:Knee laxity in the setting of anterior cruciate ligament (ACL) injury is often assessed through physical examination using the Lachman, pivot shift, and anterior drawer tests. The degree of laxity noted on these examinations may influence treatment decisions and prognosis. HYPOTHESIS:Increased preoperative knee laxity is associated with increased risk of revision ACL reconstruction, increased risk of contralateral ACL reconstruction, and poorer patient-reported outcomes at 6 years postoperatively. STUDY DESIGN:Cohort study; Level of evidence, 2. METHODS:2333 patients who underwent primary isolated ACL reconstruction without additional ligament injury were identified. Patients reported by the operating surgeons to have an International Knee Documentation Committee (IKDC) grade D Lachman, anterior drawer, or pivot shift examination were classified as having a high-grade laxity. Multiple logistic regression models were used to evaluate whether having high-grade preoperative laxity was predictive of increased odds of undergoing subsequent revision or contralateral ACL reconstruction within 6 years of the index procedure, controlling for patient age, sex, body mass index, Marx activity level, sport, graft type, medial meniscal treatment, and lateral meniscal treatment. Multiple linear regression modeling was used to evaluate whether having high-grade preoperative laxity was predictive of poorer IKDC or Knee injury and Osteoarthritis Outcome Score Knee-Related Quality of Life (KOOS-QOL) scores at 6 years postoperatively, after controlling for baseline score, patient age, ethnicity, sex, body mass index, marital status, smoking status, sport participation, competition level, Marx activity rating score, graft type, and articular cartilage and meniscal status. RESULTS:In total, 743 of 2325 patients (32.0%) were noted to have high-grade laxity on at least 1 physical examination test. High-grade Lachman was noted in 334 patients (14.4%), high-grade pivot shift was noted in 617 patients (26.5%), and high-grade anterior drawer was noted in 233 patients (10.0%). Six-year revision and contralateral ACL reconstruction data were available for 2129 patients (91.6%). High-grade prereconstruction Lachman was associated with significantly increased odds of ACL graft revision (odds ratio [OR], 1.76; 95% CI, 1.10-2.80, P = .02) and contralateral ACL reconstruction (OR, 1.68; 95% CI, 1.09-2.69; P = .019). High-grade prereconstruction pivot shift was associated with significantly increased odds of ACL graft revision (OR, 1.75; 95% CI, 1.19-2.54, P = .002) but not with significantly increased odds of contralateral ACL reconstruction (OR, 1.30; 95% CI, 0.89-1.87; P = .16). High-grade prereconstruction laxity was associated with statistically significantly lower 6-year IKDC (β = -2.26, P = .003), KOOS-QOL (β = -2.67, P = .015), and Marx activity scores (β = -0.54, P = .020), but these differences did not approach clinically relevant differences in patient-reported outcomes. CONCLUSION:High-grade preoperative knee laxity is predictive of increased odds of revision ACL reconstruction and contralateral ACL reconstruction 6 years after ACL reconstruction. Poorer patient-reported outcome scores in the high-grade laxity group were also noted, but the difference did not reach a level of clinical relevance.