Summary

OA is more common within 5 years after MLKI than ACL reconstruction, and MLKI patients with the combination of age > 30 y, reoperation for motion loss, partial meniscectomy, and either depression or tobacco use are at the greatest risk.

Abstract

Purpose

The progression of posttraumatic osteoarthritis (OA) is likely multifactorial involving biochemical and biomechanical changes secondary to the injury. Both the inflammatory response and postoperative biomechanical changes that may contribute to OA progression may also be magnified after surgical treatment of multiple ligament knee injuries (MLKIs) when compared to anterior cruciate ligament (ACL) injury; however, the incidence of OA has not been directly compared after ACL and MLKI reconstructions. The purposes of this claims database study were to 1) compare the incidence of OA diagnoses between MLKI and ACL-injured patients, and 2) utilize a machine learning approach to identify risk factors for OA diagnosis following MLKI. We hypothesized that the incidence of OA diagnosis within 5 years of injury would be greater after MLKI than isolated ACL injury and that the risk factors of OA diagnosis would include increased age, obesity, female sex, and meniscal treatment.

Methods

The PearlDiver Mariner database was used in this study which contains insurance claims information on more than 151 million orthopaedic patients. Two cohorts were identified for this study using Current Procedural Terminology (CPT) codes and included those between the ages of 16 and 60 that underwent isolated ACL (n=114,282) vs. MLKI reconstruction (n=3,325) after January 1, 2010 with active insurance coverage spanning from one year prior to and five years after the index surgical procedure. Demographic factors, concomitant meniscus and cartilage procedures, and subsequent reoperation to restoring motion were recorded as was the prevalence of knee OA diagnosis with five years of the index surgical procedure. OA prevalence, demographic and surgical factors were compared 1) between ACL and MLKI groups and 2) between MLKI patients with and without OA diagnosis using independent t-tests or Chi-square tests as appropriate. In addition, we performed an exploratory Classification and Regression Tree (CART) machine learning analysis to identify factors most related to OA development after MLKI but also the interplay between those factors.

Results

A significantly greater proportion of MLKI patients were diagnosed with knee OA within five years of surgery (MLKI=299/3,325(9.0%) vs. ACL=6,955/114,282(5.5%), p<0.0001; Odds Ratio=1.52 [95%CI: 1.34,1.71], p<0.001). Factors associated with increased odds of OA diagnosis after MLKI reconstruction included age>30 y (OR=5.9), reoperation to restore motion (OR=2.54), obesity (OR=1.96), depression (OR=1.85), partial meniscectomy (OR1.85), and tobacco use. Concomitant meniscus repair was protective against OA diagnosis (OR=0.37). Inputting the significant risk factors, the decision tree analysis identified age>30 (Variable Importance (VI)=59), motion-restoring surgery (VI=14), and partial meniscectomy (VI=8) as the most important variables with tobacco use, depression, and obesity each with VI=6.

Conclusions

The prevalence was greater after MLKI than ACL reconstruction. Several modifiable factors that increase risk of OA after MLKI were identified and include the need for motion-restoring surgery, obesity, tobacco use, and depression. While the risk of OA after MLKI reconstruction is undoubtedly multifactorial, the current results highlight the importance of regaining range of motion while holistically promoting a healthy lifestyle through weight loss, smoking cessation, and improve emotional wellbeing.