Low-intensity Pulsed Ultrasound Stimulation for Tendon-Bone Healing: A Dose-dependent Study.

Abstract This study aimed to evaluate the dosage effect of low-intensity pulsed ultrasound stimulation (LIPUS) on tendon-bone (T-B) healing. Standard partial patellectomies were performed on 120 mature New Zealand rabbits randomly assigned into three groups: a control group (daily mock sonication, 20 min), a qd group (daily ultra-sonication, 20 min), and a bid group (ultra-sonication twice a day, 20 min each time). The rabbits were sacrificed 8 or 16 weeks postoperatively, and the microarchitectural, histological, and mechanical properties of the patella-patellar tendon (PPT) interface were evaluated. Micro-computed tomography analysis showed that the bid group exhibited more new bone formation and mineralization than the other groups in the T-B healing position at both 8 and 16 weeks postoperatively. Histological assessments confirmed the bid group exhibited a significantly better PPT interface than the other groups, as shown by the increased formation and remodeling of newly formed bone and a fibrocartilage layer. The biomechanical properties of the regenerated PPT interface significantly improved in the bid group. LIPUS treatment twice a day was more effective than the once-a-day treatment on tendon-bone healing.