Table 2

Preoperative and 2-year postoperative KOOS and percentage of patients with KOOS within the normative range

KOOS subscaleCohortPreoperative2 Years
Mean (SD)Percentage within normative range (95% CI)β (95% CI)p ValueMean (SD)Percentage within normative range (95% CI)β (95% CI)p Value
PainNAR87.0 (10.7)63.1 (52.8 to 73.4)11.5 (8.0 to 15.0)<0.00193.5 (10.3)89.3 (82.7 to 95.9)7.6 (4.4 to 10.9)<0.001
NKLR75.9 (16.8)34.9 (33.0 to 36.8)86.0 (15.1)65.3 (63.5 to 67.1)
SymptomsNAR82.6 (12.9)59.5 (49.0 to 70.0)9.5 (5.8 to 13.1)<0.00189.2 (11.9)86.9 (79.7 to 94.1)11.9 (8.0 to 15.8)<0.001
NKLR73.6 (17.3)39.6 (37.6 to 41.6)77.4 (18.0)51.4 (49.5 to 53.3)
ADLNAR94.7 (10.1)81.0 (72.6 to 89.4)10.0 (6.5 to 13.3)<0.00198.0 (5.6)94.0 (88.9 to 99.1)5.5 (2.8 to 8.3)<0.001
NKLR85.1 (16.3)50.5 (48.5 to 52.5)92.5 (12.8)75.8 (74.2 to 77.4)
SportsNAR69.1 (21.4)61.9 (51.5 to 72.3)24.6 (19.0 to 30.2)<0.00185.1 (16.2)86.9 (79.7 to 94.1)17.7 (12.1 to 23.2)<0.001
NKLR45.2 (26.6)23.3 (21.6 to 25.0)67.6 (25.9)57.2 (55.3 to 59.1)
QoLNAR49.6 (20.0)41.7 (31.2 to 52.2)13.8 (9.9 to 17.8)<0.00178.6 (20.4)85.7 (78.2 to 93.2)10.8 (5.9 to 15.7)<0.001
NKLR36.0 (18.1)18.2 (16.6 to 19.8)67.7 (22.7)68.4 (66.6 to 70.2)
  • β Represents the difference in KOOS associated with the NAR cohort versus the NKLR after adjustment for sex, age, time from injury to surgery, meniscus injury at ACLR and cartilage injury at ACLR. Positive values indicate higher scores in the NAR cohort.

  • ACLR, anterior cruciate ligament reconstruction; ADL, activities of daily living; KOOS, Knee Injury and Osteoarthritis Outcome Score; NAR, Norwegian Research Center for Active Rehabilitation; NKLR, Norwegian National Knee Ligament Registry; QoL, quality of life.