Demographic and surgical characteristics in patients who do not achieve minimal important change in the KOOS Sport/Rec and QoL after ACL reconstruction: a comparative study from the Swedish National Knee Ligament Registry

Objectives: This study aimed to compare demographic and surgical characteristics between patients who do and do not achieve minimal important change (MIC) in the Knee injury and Osteoarthritis Outcome Score (KOOS) Sports and Recreation (Sport/Rec) and Quality of Life (QoL) subscales 1 year after anterior cruciate ligament reconstruction.

Design: Comparative cross-sectional.

Setting: The MIC for the KOOS Sport/Rec subscale was ≥12.1 and ≥18.3 for the KOOS QoL subscale from before surgery to 1-year follow-up using data from the Swedish National Knee Ligament Registry.

Participants: In total 16 131 patients were included: 11 172 (69%) with no MIC for the Sport/Rec scale, and 10 641 (66%) for the QoL.

Results: Patients with no MIC for Sport/Rec and QoL had a higher body mass index (BMI) (24.8±3.5 vs 24.6±3.3 and 24.7±3.5 vs 24.6±3.2, respectively, p<0.0001), were younger (years) at time of surgery (28.5±10.3 vs 29.1±10.8 and 27.4±9.8 vs 29.7±11.0, respectively, p=0.0002 and <0.0001), had longer time from injury to surgery (months) (Sports/Rec 22.0±38.5 vs 19.3±36.6, respectively, p=0.0002), and greater rates of concomitant cartilage injuries especially to the lateral femoral condyle (22.7% vs 19.4% and 23.3% vs 19.0%, respectively, p=0.001 and p=0.005) compared with patients who achieved the MIC. A smaller proportion of patients treated with a hamstring tendon autograft had no MIC (91.4%) compared with patients with MIC (94.1%).

Conclusions: Patients with no MIC for KOOS Sport/Rec and QoL subscales had a higher BMI, longer time from injury to surgery and were younger at the time of surgery compared with patients who did achieve MIC. Although differences were small, they may reframe management strategies with patients who have these characteristics.