Increased Cartilage Synthesis Is Associated With Cumulative Bone Stimulus And Season Long Injury Incidence

Impact loading alterations have been associated with cartilage metabolism changes before and after joint injury; however, the relationship and variation in these metrics over an athletic season is unclear. If cumulative impact load metrics and cartilage metabolism biomarkers are found to be strongly correlated, it may be possible to use the less invasive impact load metrics as a surrogate to the biological changes occurring at the joint level and a precursor for injury. PURPOSE: To preliminarily establish whether a metric of cumulative impact load and cartilage biomarkers are related to season long lower extremity injury incidence and evaluate the relationship between these variables. METHODS: Eleven collegiate women’s basketball athletes (height:1.86 meters, mass:82.0 kilograms, age:20.54 years) participated in a prospective case-series evaluating lower extremity impact load, serum cartilage biomarkers, and season injury incidence. Cartilage synthesis (CPII, CS846) and degradation (C2C) biomarkers were evaluated at 6 season timepoints. Impact load metrics (cumulative bone stimulus) were collected during practices using inertial measurement units secured to the distal medial tibiae. Injury was defined as restriction of participation for 1 or more days beyond day of initial injury. Cumulative impact load metrics were calculated over the week prior to the scheduled blood draws for analysis. Point biserial and Pearson product moment correlations were utilized to determine the relationship between impact load metrics and cartilage serum biomarkers. RESULTS: Greater cumulative bone stimulus was associated with increased CPII levels in the post-season for right (r = 0.694, p = 0.026) and left (r = 0.747, p = 0.013) limbs. Greater CS846 levels at off-season-1 (r = 0.729, p = 0.017), and at the beginning of the competitive season (r = 0.645, p = 0.044) were associated with season long injury incidence. CONCLUSIONS: Increased cartilage synthesis at various timepoints was related to increased cumulative bone stimulus metrics and season-long injury incidence. These relationships should be further evaluated to determine predictive capabilities in larger cohorts. This work was funded by the Arthroscopic Association of North America