Delayed cartilage oligomeric matrix protein response to loading is associated with femoral cartilage composition post-ACLR

PurposeTo determine associations between immediate and delayed response of serum cartilage oligomeric matrix protein (sCOMP) to loading (i.e., 3000 walking steps) and femoral cartilage interlimb T1 rho relaxation times in individual's post-anterior cruciate ligament reconstruction (ACLR).MethodsThis cross-sectional study included 20 individuals 6-12 months following primary ACLR (65% female, 20.5 +/- 4.0 years old, 24.9 +/- 3.0 kg/m(2), 7.3 +/- 1.5 months post-ACLR). Serum samples were collected prior to, immediately following, and 3.5 h following walking 3000 steps on a treadmill at habitual walking speed. sCOMP concentrations were processed using enzyme-linked immunosorbent assays. Immediate and delayed absolute sCOMP responses to loading were evaluated immediately and 3.5 h post-walking, respectively. Participants underwent bilateral magnetic resonance imaging with T1 rho sequences to calculate resting femoral cartilage interlimb T1 rho relaxation time ratios between limbs (i.e., ACLR/Uninjured limb). Linear regression models were fitted to determine associations between sCOMP response to loading and femoral cartilage T1 rho outcomes controlling for pre-loading sCOMP concentrations.ResultsGreater increases in delayed sCOMP response to loading were associated with greater lateral ( increment R-2 = 0.29, p = 0.02) but not medial ( increment R-2 < 0.01, p = 0.99) femoral cartilage interlimb T1 rho ratios. Associations between immediate sCOMP response to loading with femoral cartilage interlimb T1 rho ratios were weak and non-significant ( increment R-2 range = 0.02-0.09, p range = 0.21-0.58).ConclusionGreater delayed sCOMP response to loading, a biomarker of cartilage breakdown, is associated with worse lateral femoral cartilage composition in the ACLR limb compared to the uninjured limb. Delayed sCOMP response to loading may be a more indicative metabolic indicator linked to deleterious changes in composition than immediate sCOMP response.

Automated summary

This study aimed to determine the associations between immediate and delayed response of serum cartilage oligomeric matrix protein (sCOMP) to loading and femoral cartilage interlimb T1 rho relaxation times following ACL reconstruction. The results indicated that greater delayed sCOMP response to loading was associated with worse lateral femoral cartilage composition.