It is unclear whether the edge of the ruptured rotator cuff tendon is active in healing. We examined procollagen synthesis at this edge, and its association with preoperative clinical parameters and postoperative cuff integrity. Nineteen patients (average age 58 years) with full-thickness rotator cuff rupture were enrolled in the study. The edge of the ruptured tendon was sampled during open rotator cuff surgery. As controls, age-matched rotator cuff tendons with no gross rupture were taken from 5 fresh cadavers. Production of procollagen types I and III was examined by real-time reverse transcription-polymerase chain reaction and Western blot analysis. Using magnetic resonance imaging, postoperative cuff integrity was evaluated by the system of Sugaya's classification and then scored; 5 points for type I to 1 point for type V. mRNA expression of type I and III procollagen at the edges of ruptured rotator cuff tendons was significantly greater than in control tendons (P=0.0097 and 0.0014, respectively). Western blot analysis consistently showed greater production of procollagen types I and III at the edges of ruptured rotator cuff tendons, compared with control tendons. Procollagen-mRNA expression was significantly correlated with postoperative rotator cuff integrity (type I: r = 0.63 with P = 0.04, type III: r = 0.60 with P = 0.03) and period from symptom onset (type I: r = -0.75 with P = 0.0005, type III: r = -0.52 with P = 0.0331), but not with rupture size. In rotator cuff tendon rupture, early surgical intervention may optimize postoperative structural outcome.
