Background:The Patient-Reported Outcomes Measurement Information System (PROMIS) computer adaptive testing (CAT) is a patient-reported outcome metric that has been validated for anterior cruciate ligament (ACL) injuries, ACL reconstructions, and meniscal injuries. Thus far, the system has not been validated for multiligament knee injuries. The Multiligament Quality of Life (MLQOL) questionnaire is a validated, disease-specific patient-reported outcome instrument for this population that can serve as a gold standard for validation of the newer PROMIS.Purpose/Hypothesis:The purpose of this study was to further validate the PROMIS CAT for multiligament knee reconstruction. We hypothesized that the PROMIS CAT modules would correlate with the Lysholm knee score (Lysholm), Tegner activity scale (Tegner), and MLQOL for postoperative multiligamentous knee injury patients and that the PROMIS CAT would use fewer question items than the Lysholm, Tegner, and MLQOL while still avoiding floor and ceiling effects.Study Design:Cohort study; Level of evidence, 2.Methods:A total of 30 patients meeting the inclusion criteria were retrospectively identified and agreed to participate (87% male; mean ± SD age, 36.3 ± 13.5 years). Consenting patients were administered the Lysholm, Tegner, MLQOL, and PROMIS CAT for Physical Function, Mobility, and Pain Interference. Spearman correlations were used to test agreement across survey instruments. Floor and ceiling effects were assessed for all instruments.Results:PROMIS Pain Interference had excellent correlation with MLQOL Activity Limitations (r = 0.71, P < .0001). Excellent-good correlations were detected between PROMIS Physical Function and MLQOL Activity Limitations (r = –0.63, P = .0002) and PROMIS Mobility and MLQOL Activity Limitations (r = –0.62, P < .0002). Good correlations were found between the Lysholm and the PROMIS Physical Function and PROMIS Mobility (for each, r = 0.50, P = .005). Additional correlations were present with other subsections. There were no floor or ceiling effects for the PROMIS CAT instrument in any category.Conclusion:The PROMIS CAT correlates well with existing outcome measures for multiligament knee injury patients without floor or ceiling effects. The PROMIS CAT is a concise adjunct to the validated injury-specific outcome tool for multiligament knee injury. Surgeons should consider implementing the PROMIS CAT because of its broad validity, including ACL injuries, meniscal tears, and now multiligament knee injuries.