PURPOSE: The purpose of this study was to evaluate laxity and functional outcome of displaced tibial spine fractures in skeletally immature patients treated with arthroscopic reduction and internal fixation. TYPE OF STUDY: Retrospective case series. METHODS: Six patients (mean age, 12.0 years old) underwent subjective, objective, and instrumented knee laxity assessment at minimum 2 years (mean, 3.2 years) of follow-up time after arthroscopic reduction and 3.5-mm cannulated screw fixation of (Meyers and McKeever type III) tibial spine fractures. RESULTS: Physical examination showed persistent laxity, with an abnormal Lachman examination in 5 of 6 patients and an abnormal pivot-shift examination in 2 of 6 patients. Instrumented knee laxity (KT-1000) showed greater than 3-mm manual-maximum side-to-side difference in 4 of 6 patients. Functional assessment revealed excellent function, with a mean Lysholm score of 99.5 (range, 98-100), mean Marshall score of 49.0 (range, 47-50), and mean Tegner score of 8.7 (range, 7-9). CONCLUSIONS: Arthroscopic reduction and internal fixation of type III tibial spine fractures in skeletally immature patients results in persistent laxity but excellent functional outcome.