Higher pyruvate levels after Achilles tendon rupture surgery could be used as a prognostic biomarker of an improved patient outcome

Purpose The primary aim of this study was to assess the relationship between the metabolites lactate and pyruvate in the healing tendon after Achilles tendon rupture (ATR) and patient‐reported outcome at 6 and 12 months. A secondary aim was to evaluate which underlying factors regulate lactate and pyruvate concentrations. Methods Lactate and pyruvate concentrations were measured two weeks post‐operatively in both the healing‐ and healthy Achilles tendon in 109 patients (90 men, 19 women; mean age 40 ± 7.9 years). Patient demographics, degree of physical activity, timing of surgery, operation time, patient‐reported loading and step counts were investigated in relation to metabolite concentrations. At 6 and 12 months, the Achilles tendon Total Rupture Score (ATRS) questionnaire was used to assess patient outcome. Results The mean number of steps taken during the post‐operative days 1–10 was the only factor significantly related to the mean concentration of lactate ( R 2  = 0.34, p  = 0.038), and pyruvate ( R 2  = 0.46, p  = 0.006). Pyruvate was demonstrated as the only factor significantly associated with ATRS at both 6 months ( R 2  = 0.32, p  = 0.003) and at 12 months ( R 2  = 0.37, p  = 0.004) using multiple linear regression. Conclusion The mean concentration of pyruvate during early ATR healing may predict patient outcome at 6 and 12 months post‐operatively and possibly be used as a biomarker of healing. Early mobilization with an increased number of steps taken is an important clinical strategy to improve the metabolite concentrations during healing. Level of evidence III