Loss of normal knee motion after anterior cruciate ligament reconstruction is associated with radiographic arthritic changes after surgery.

Shelbourne KD, Urch SE, Gray T, Freeman H. Am J Sports Med. 2012 Jan;40(1):108-13.

SMR has summarized several articles regarding the risk of knee osteoarthritis (OA) after an anterior cruciate ligament tear (see below). The risk of knee OA is increased among patients with ACL tears when they also have concurrent meniscal or cartilage damage at the time of surgery or a high body mass index. Some data indicates that limited knee range of motion (ROM) may be another risk factor for OA among patients with ACL tears but more research is needed to confirm these findings. Therefore, Shelbourne et al. assessed whether the prevalence of radiographic knee osteoarthritis was higher in patients who had abnormal knee ROM after an ACL reconstruction compared to patients with normal knee ROM; even when controlling for meniscal or cartilage damage. The study included 780 patients (on average 25 years of age at the time of surgery) who between 1987 and 2004 underwent ACL reconstruction with autogenous patellar tendon graft and did not have osteoarthritis at the time of surgery and did not undergo bilateral ACL reconstructions. Patients were assessed at 2, 5, 10, and 20 years after surgery. To be included in these analyses patients had to have at least 5 years of follow-up (the average follow-up was 10.5 years [range 5 to 21.2 years]). Meniscal and cartilage pathology was assessed during the ACL reconstruction. After surgery, all of the patients underwent a rehabilitation program that emphasized gaining full knee ROM as soon as possible after surgery (accelerated rehabilitation program). Standard goniometric procedures were used to measure knee ROM (flexion and extension) at the time of return to activity (typically 6 months after surgery) and five-years after surgery (reliability and measurement error data were not provided). The authors defined normal ROM based on the International Knee Documentation Committee criteria: normal knee extension = within 2 degrees of opposite normal knee, normal knee flexion = within 5 degrees of opposite normal knee (a knee was defined as having abnormal knee ROM if flexion or extension was limited). Knee radiographs (posteroanterior, lateral, merchant/sunrise) were assessed and defined as abnormal if there was any evidence of OA-related changes (i.e., osteophytes [bone spurs], sclerosis, change in bone shape, joint space narrowing).  At 5-years post-reconstruction 89% and 79% of patients had normal knee extension and flexion; respectively. Compared to when the patients return to activity 69% of patients had the same ROM classification as 5-year follow-up: 479 (61%) patients were normal at both time points, 60 (8%) patients were abnormal at both time points, 102 (13%) patients went from normal to abnormal at the later follow-up, and 139 (18%) patients went from abnormal to normal ROM. Risk factors for abnormal radiographs (OA) were abnormal knee flexion at return to activity, abnormal knee extension at 5-years post-reconstruction, abnormal flexion at 5-years post-reconstruction, partial medial meniscectomy, or cartilage damage. When the authors examined subgroups of patients based on meniscal pathology (e.g., both meniscus intact, medial meniscal pathology) they still found that the prevalence of knee osteoarthritis was higher among patients with abnormal ROM at 5-years post-reconstruction. It was estimated that the odds of having knee OA were 2 times higher among patients with abnormal knee ROM at 5-years post reconstruction even when controlling for meniscus or cartilage pathology. 

This study is interesting because it highlights the importance of ROM long after a patient returns to full activity. While the study cannot determine if the decrease in ROM is the cause of OA or a result of early OA it does highlight that ROM is a measure that we need to pay more attention to. It might be important for us to encourage patients to continue performing rehabilitation exercises long after their return to full activity. Perhaps the point of return to activity should not be perceived as the end of the patient’s rehabilitation but the beginning of a new phase of rehabilitation with the goals of minimizing the risk of reinjury and OA. It may be advantageous to evaluate their progress every few months or years and properly assess how the joint is responding to the initial injury. How do you treat your patients after they are released to return to full activity?  Do you coordinate with a strength coach to allow the patient to continue to progress? 

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Shelbourne KD, Urch SE, Gray T, & Freeman H (2012). Loss of normal knee motion after anterior cruciate ligament reconstruction is associated with radiographic arthritic changes after surgery. The American Journal of Sports Medicine, 40 (1), 108-13 PMID: 21989129