Fewer daily steps are associated with greater cartilage oligomeric matrix protein response to loading post-ACL reconstruction

Aberrant joint loading contributes to the development of posttraumatic knee osteoarthritis (PTOA) following anterior cruciate ligament reconstruction (ACLR); yet little is known about the association between joint loading due to daily walking and cartilage health post-ACLR. Accelerometer-based measures of daily steps and cadence (i.e., rate of steps/min) provide information regarding daily walking in a real-world setting. The purpose of this study was to determine the association between changes in serum cartilage oligomeric matrix protein (COMP; % increment COMP), a mechanosensitive biomarker that is associated with osteoarthritis progression, following a standardized walking protocol and daily walking in individuals with ACLR and uninjured controls. Daily walking was assessed over 7 days using an accelerometer worn on the right hip in 31 individuals with ACLR and 21 controls and quantified as mean steps/day and time spent in >= 100 steps/min. Serum COMP was measured before and following a 3000-step walking protocol at a preferred speed. % increment COMP was calculated as a change in COMP relative to the prewalking value. Linear regressions were used to examine associations between daily walking and % increment COMP after adjusting for preferred speed. Fewer daily steps (Delta R-2 = 0.18, p = 0.02) and fewer minutes spent in >= 100 steps/min (Delta R-2 = 0.16, p = 0.03) were associated with greater % increment COMP following walking in individuals with ACLR; no statistically significant associations existed in controls (daily steps: Delta R-2 = 0.03, p = 0.47; time >= 100 steps/min: Delta R-2 < 0.01, p = 0.81). Clinical significance: Individuals with ACLR who engage in less daily walking undergo greater %Delta COMP, which may represent greater cartilage degradation or turnover in response to walking.

Automated summary

The study found that in individuals undergoing ACLR, fewer daily steps and less time spent walking at speeds exceeding 100 steps/min were significantly associated with a higher increase in COMP after walking. This suggests that ACLR patients engaging in less daily walking may experience greater cartilage degradation or turnover in response to walking.