BackgroundThe aim of this study was to investigate differences in concomitant injury patterns and their treatment in patients undergoing early (≤ 12 weeks) and delayed (> 12 weeks) primary multiligament posterior cruciate ligament (PCL) reconstruction (PCL-R).MethodsThis study was a retrospective chart review of patients undergoing primary multiligament PCL-R at a single institution between 2008 and 2020. Multiligament PCL-R was defined as PCL-R and concurrent surgical treatment of one or more additional knee ligament(s). Exclusion criteria included isolated PCL-R, PCL repair, and missing data for any variable. Patients were dichotomized into early (≤ 12 weeks) and delayed (> 12 weeks) PCL-R groups based on the time elapsed between injury and surgery. Between-group comparison of variables were conducted with the Chi-square, Fisher’s exact, and independent samples t-tests.ResultsA total of 148 patients were eligible for analysis, with 57 (38.5%) patients in the early and 91 (61.1%) patients in the delayed multiligament PCL-R groups. Concomitant LCL/PLC reconstruction (LCL-R/PLC-R) was performed in 55 (60%) of delayed multiligament PCL-Rs and 23 (40%) of early PCL-Rs (p= 0.02). Despite similar rates of meniscus injury, concomitant meniscus surgery was significantly more prevalent in the early (n= 25, 44%) versus delayed (n= 19, 21%) multiligament PCL-R group (p= 0.003), with a significantly greater proportion of medial meniscus surgeries performed in the early (n= 16, 28%) compared to delayed (n= 13, 14%) PCL-R group (p= 0.04). The prevalence of knee cartilage injury was significantly different between the early (n= 12, 24%) and delayed (n= 41, 46%) multiligament PCL-R groups (p= 0.01), with more frequent involvement of the lateral (n= 17, 19% vs.n= 3, 5%, respectively;p= 0.04) and medial (n= 31, 34% vs.n= 6, 11%, respectively;p= 0.005) femoral condyles in the delayed compared to the early PCL-R group.ConclusionsGiven higher rates of chondral pathology and medial meniscus surgery seen in delayed multiligament PCL-R, early management of PCL-based multiligament knee injury is recommended to restore knee stability and potentially prevent the development of further intraarticular injury.Level of evidenceLevel III.