An isolated rupture of the posterior cruciate ligament results in reduced preoperative knee function in comparison with an anterior cruciate ligament injury

Purpose To investigate differences in preoperative knee function (Knee Injury and Osteoarthritis Outcome Score, KOOS), the time period from injury to surgery, and associated injuries when comparing primary isolated posterior cruciate ligament (PCL) and primary anterior cruciate ligament (ACL) reconstructions. Methods Isolated primary ACL and PCL reconstructions registered in the Norwegian National Knee Ligament Registry from 2004 through 2010 were included (n = 71 primary PCLs and 9,649 primary ACLs). Linear regression analysis was used to evaluate the preoperative KOOS subscale values. Results The preoperative KOOS in the PCL group (n = 71) and ACL group (n = 9,649) was significantly different for the subscales symptoms (mean difference, −8.4; 95 % CI: −12.8 to −4.0), pain (mean difference, −15.9; 95 % CI: −20.3 to −11.4), activities of daily living (mean difference, −12.9; 95 % CI: −17.4 to −8.4), sport and recreation (mean difference, −15.9; 95 % CI: −22.6 to −9.3), and quality of life (mean difference, −7.9; 95 % CI: −12.4 to −3.5). The primary isolated PCL‐reconstructed knees had a median time from injury to surgery of 21 months in comparison with 8 months for ACL injuries. The ACL‐injured knees had more associated injuries (meniscus and full‐thickness cartilage lesions) than the PCL‐injured knees. Conclusion Surgically treated knees with an isolated rupture of the PCL exhibited worse knee function preoperatively compared with knees with an isolated ACL injury; in addition, the delay to surgery was longer. Meniscal lesions were found more frequently in ACL‐injured knees. Level of evidence Prospective cohort study, evidence Level I.