Summary

Clinicians should be aware of both modifiable and non-modifiable risk factors for not achieving a MIC after ACL-R and thus, should adjust treatment and establish realistic expectations for the patient.

Abstract

Objectives: To investigate factors associated with not achieving a minimal important change (MIC) in the Knee injury and Osteoarthritis Outcome Score (KOOS) Function, Sports, and Recreational Activities (Sport/Rec), and Knee-Related Quality of Life (QoL) subscales 1 year after anterior cruciate ligament reconstruction (ACL-R).

Methods

This study used data from the Swedish National Knee Ligament Registry. Multivariable logistic regression models were used to determine factors associated with not achieving a MIC. The KOOS subscales Sport/Rec and QoL were dichotomized (not achieving/achieving MIC; the MICs for the Sport/Rec and QoL subscales were 12.1 and 18.3 respectively) and combined into one single variable (Sport & QoL).

Results

Of 16,131 included patients 44% did not achieve the MIC for the combined Sport/Rec and QoL subscales 1 year after ACL-R. Older patients (OR 0.91, 0.88-0.94; p<0.0001), males (OR 0.93, 0.87-0.99; p=0.034) and patients receiving hamstring tendon autograft ACL-R (OR 0.70, 0.60-0.81; p<0.0001) had decreased odds of not achieving the MIC 1 year after ACL-R compared to younger patients, females and patients receiving patellar tendon autograft. In addition, patients with cartilage injuries (OR 1.17, 1.09-1.27; p<0.0001) and higher pre-operative KOOS Sport/Rec and QoL scores (OR 1.34, 1.31-1.36; p<0.0001) had increased odds of not achieving the MIC.

Conclusion

Females, younger patients, and patients with higher pre-operative Sport/Rec and QoL KOOS scores, and cartilage injuries, are less likely to benefit from ACL-R and subsequently, have a lower probability for improved Sport/Rec and QoL scores after ACL-R. In addition, graft choice may also be associated with the risk of not achieving the MIC.