Background
Time between injury and ACL reconstruction (ACLR) may influence baseline knee-related and general-health related patient-reported outcome measures (PROMs). Despite the common use of PROMs as main outcomes in clinical studies, this has never been evaluated.
Hypothesis/Purpose
To determine whether time from injury to ACLR influences: (1) baseline PROMs; (2) pattern and prevalence of concurrent articular cartilage and meniscal injury.
Study design
Cross-sectional (level III).
Methods
1,192 patients from the MOON consortium who underwent primary ACLR were eligible. ‘Acute’ ACLR was defined as <3 months (n=853; 72%), and ‘chronic’ as >6 months (n=339; 28%) from injury. Patient demographic, surgical characteristics (articular cartilage injury, medial [MM] and lateral [LM] meniscal tears), and baseline PROMs (Marx activity scale, IKDC, KOOS, SF-36) were collected. To determine whether time from injury to ACLR influences: (1) baseline PROMs; (2) pattern and prevalence of concurrent articular cartilage and meniscal injury. Analysis of covariance models were used to adjust for confounders on baseline outcome scores (age, sex, body mass index [BMI], smoking status, competition level, education).
Results
The median age was 23 years (IQR 17–35), n=530 (45%) were female, and median BMI was 25.0 kg/m2 (IQR 22.3–27.9); however, the chronic group was older, had higher BMI and fewer collegiate athletes. A significantly greater number of partial LM tears were seen acutely (14% vs. 6%; p<0.001), but more meniscal tears overall (74% vs 63%; p=0.001), complete MM tears (49% vs. 23%; p<0.001), and articular cartilage injury (54% vs. 33%; p<0.001) chronically. After controlling for confounders, chronic ACLR patients reported significantly lower baseline Marx (7.8 vs. 12.1, p<0.001), but higher baseline IKDC, physical function SF-36, and all KOOS subscales except quality of life (QoL). However, only the sports and recreation subscale exceeded the minimum clinically importance difference of 8 points (62.3 vs. 48.3; p<0.001).
Conclusion
After controlling for age, sex, competition level, smoking and BMI, chronic ACLR patients participated in less pivoting and cutting sports, but reported better pain/function. Whether decreased activity is deliberate after ACL injury, or these are simply less active patients who may be treated successfully without surgery warrants further investigation. Non-randomized studies that utilize PROMs should consider time from injury in design and data interpretation.
