Patients With An Isolated PCL Injury Improve As Much As The ACL Patients From Surgery Measured By KOOS After 2 Years

OBJECTIVES: Background: Isolated posterior cruciate ligament (PCL) injuries are severe knee injuries, often caused by a sports injury or a traffic accident and can be treated either conservatively (with a brace and exercises) or by reconstructive surgery. Results reported after reconstructive surgery contain a mixture of isolated and combined knee ligament injuries. Consequently the results after such surgery are not documented thoroughly. Hypothesis: Patients undergoing PCL reconstruction demonstrate the same improvements as patients treated with ACL reconstruction measured by Knee Osteoarthritis Outcome Score (KOOS) two years postoperatively. STUDY DESIGN: The study is a prospective cohort study based on registry data. Evidence level II. METHODS: The Norwegian Knee Ligament Registry contains data including patient reported KOOS values on 295 PCL injuries (71 isolated PCL injuries) and some 10.000 ACL injuries registered between 2004 and 2010. The changes in KOOS scores from preoperative values to two years follow up after surgery were compared by paired sample t-test in each of the two patient groups. The main outcome measure was patient reported outcome measured by changes in the KOOS quality of life (QoL) subscale. Then the changes for the PCL patients were compared to the corresponding changes for the ACL patients. RESULTS: The delay to surgery was significantly longer for PCL patients compared to the ACL patients (median 21.5months vs 8.0 months). Most surgeries were performed using single bundle hamstring graft for both PCL and ACL reconstruction. PCL reconstructed patients had an improved patient reported knee function postoperatively measured by KOOS at two years with improvement in all KOOS subscales as follows; Pain: 15.1, CI (8.5-21.8), p<0.01. Symptoms: 0.9, CI (-6.6-8.3), p=0.82. ADL: 13.2, CI (6.6-13.9), p<0.01. Sports: 20.7, CI (11.8-29.4), p<0.01. QoL: 26.6, CI (18.9-34.2), p<0.01. The reported results for the ACL patients were; Pain: 10.5, CI (10.2-11.5), p<0.01. Symptoms: 5.1, CI (4.1-5.2), p<0.01. ADL: 8.1, CI (7.7-8.6), p<0.01. Sports: 23.0 CI (22.2-23.8), p<0.01. QoL: 31.7, CI (31.0-32.4), p<0.01. The increments in KOOS for the PCL patients are similar to those of the ACL patients. For the KOOS subscale pain the improvements was larger than for ACL treated patients but no significant difference was found. CONCLUSION: Patients undergoing PCL reconstruction with single bundle hamstring graft can expect the same improvements in KOOS as patients undergoing ACL reconstruction. However the PCL patients start out with an average inferior score in all subscales and consequently end up at a lower score compared to the ACL patients for all KOOS subscales. CLINICAL RELEVANCE: The present study provides relevant information on what results to expect after single bundle PCL reconstruction. PCL reconstructed patients can achieve similar improvements to ACL reconstructed patients measured by KOOS. Improvements in surgical techniques might result in restoration of knee function to the same level as ACL injured knees. Candidates for PCL reconstruction, could be informed about these results during the decision making process. To our knowledge, this study comprises the largest material available on isolated PCL injuries treated with reconstructive surgery.