Nacox Cohort Finds Similar Knee Function After ACL Surgery or Nonsurgical Care

Key Takeaways

• IKDC-SKF scores improved over time in both treatment groups, and no significant between-group difference was detected.
• Return-to-sport rates were similar by 24 months, but return occurred earlier in the group without ACL reconstruction.
• Older age, female sex, and a new serious knee injury were associated with lower knee-function scores, and among patients aged 26 to 40 years, those undergoing ACLR were less likely to return to sport than same-age patients without ACLR.

In the NACOX multicenter prospective cohort, about three-quarters of patients returned to sport within 24 months after injury or reconstruction, while patient-reported knee function remained similar across nonsurgical and reconstruction pathways during follow-up.

Researchers analyzed 272 patients aged 15 to 40 years who entered within 6 weeks of acute ACL injury. Participants were recruited at seven Swedish public and private sites between 2016 and 2018; mean age was 25.5 years, and 52% were female. Treatment pathway was determined in routine practice through shared decision-making, and participation did not alter usual care at recruiting centers. IKDC-SKF was collected at baseline and at 3, 6, 12, and 24 months after injury or reconstruction, and return to sport was defined as regaining the preinjury Tegner level or higher. By 24 months, 170 patients had undergone ACL reconstruction at a mean of 5.6 months after injury, and younger age with higher preinjury activity in that group shaped the comparisons.

No statistically significant between-group difference in IKDC-SKF was seen at any measured time point, including early and later follow-up visits. Scores improved over time in both groups, with a time effect of P < .001. Among patients who returned to sport, the mean return time across the cohort was 6.3 months from injury or reconstruction. At 24 months, return-to-sport rates were 72% without ACLR and 77% with ACLR, a difference that was not significant (P = .286). Patients without ACLR returned sooner, at 3.5 months versus 8.1 months for the ACLR group (P < .001), and Kaplan-Meier analysis also favored earlier return without reconstruction (log-rank P = .006).

In adjusted analyses, older age, female sex, and a new serious knee injury were associated with lower IKDC-SKF scores, with P values of .003, .004, and less than .001, respectively. Among patients aged 26 to 40 years, ACL reconstruction was associated with a 3.15-fold higher risk of not returning to sport by 24 months versus non-ACLR (P = .015). Researchers tracked reinjuries and subsequent knee surgeries throughout follow-up, and a new serious knee injury was associated with worse reported knee function.

The cohort was observational and nonrandomized, with routine-care treatment selection, baseline group differences, missing follow-up data, higher nonresponse in the ACLR group, and selection bias concerns.