Is it possible to predict the outcome of an anterior cruciate ligament injury?

Sammanfattning: This thesis centers on a well-studied cohort of 100 patients, which received a treatment regimen of initial rehabilitation and activity modification to cope with Anterior Cruciate Ligament (ACL) injury. The data, collected prospectively and longitudinally, cover a span of 15 years after initial injury. The overall aim of this thesis is to describe the course of an ACL injury treated with rehabilitation and activity modification and to identify early prognostic factors of both short- and long-term outcome. The methods for evaluating outcome include patient-reported outcome scores — such as Lysholm, Tegner, and KOOS — and plain radiographs to assess radiographic findings of osteoarthritis. Further assessments include clinical laxity tests — such as Lachman and pivot-shift tests — to evaluate clinical instability as a predictor for later ACL reconstruction, as well as lateral radiographs to explore the influence of posterior-inferior tibial slope in ACL injury. The main findings show that approximately 60% of ACL-injured patients can manage without ACL reconstruction by following the treatment algorithm. Most patients in this study were able to resume pre-injury activity level, and their long-term outcome proved comparable to studies of ACL reconstruction. The study also shows that Lachman and pivot-shift tests performed at 3 months post-injury are important prognostic factors regarding the need for reconstruction; however, it is not recommended to use these tests for making decisions about ACL reconstruction in the acute phase. Another prognostic factor is the slope of the medial tibial plateau, which proved steeper in patients injured when participating in contact sports and led to a fourfold increased risk for later reconstruction in flat-sloped knees. Finally, the acute injury mechanism — with a compression-type injury as opposed to a distraction-type injury — appears to influence both the risk for meniscal injuries, not only at index injury but even later, and the need for ACL reconstruction. A compression-type injury further appears to increase the risk for future osteoarthritis, although the presence of multiple confounding factors may blur its true effect. Our results suggest the initial injury mechanism, along with anthropometric variables and clinical laxity tests, can help in predicting the outcome of ACL injury. The high percentage of copers in our study makes the decision of early reconstruction in the clinical setting questionable. Based on the data presented, we recommend at least a 3-month rehabilitation period prior to making a decision about ACL reconstruction.