Preventive Effect of Platelet-Rich Plasma on Fracture Healing in a Rat Tibial Nonunion Model: A Controlled Laboratory Experiment

Introduction Nonunion, defined as the absence of progressive healing for more than six months after fracture, remains a major challenge in orthopedic practice, leading to chronic pain, impaired mobility, and reduced quality of life. Platelet-rich plasma (PRP), an autologous concentrate of platelets and growth factors, has been proposed as a biological adjunct for enhancing tissue regeneration. Although PRP has been demonstrated as beneficial for acute fracture healing, its efficacy in established nonunion is unclear. Methods We established a rat tibial nonunion model by transverse osteotomy with circumferential periosteal removal and intramedullary fixation. Sixteen male Sprague-Dawley rats (10 weeks old) were randomly assigned to four groups (n = 4/group): Sham (osteotomy only), Nu (nonunion), Nu + PRP, and Nu + Vehicle (saline). Allogeneic pooled PRP was prepared by single centrifugation (200 × g, 7 min) for local injection (50 µL) immediately after surgery and at postoperative weeks 2 and 4. Motor function was assessed using the rotarod test, and bone healing was evaluated by micro-computed tomography (µCT) and histology (Emery fracture healing score) at postoperative week 6. Results Compared with whole blood, platelets were enriched approximately 2.5-fold in PRP (<i>p</i> = 0.002), with minimal erythrocyte contamination and moderate leukocyte enrichment. There were no significant intergroup differences in rotarod performance at any time point, although the Nu + PRP group consistently trended toward higher fall latencies. µCT revealed significantly greater cortical bridging in the Nu + PRP group compared with the Nu group (<i>p</i> = 0.005) and Nu + Vehicle group (<i>p</i> = 0.015), with scores comparable to the Sham group. Histological analysis demonstrated mature trabecular bone and a higher Emery fracture healing score in the Nu + PRP group relative to the Nu group (<i>p</i> = 0.005) and the Nu + Vehicle group (<i>p</i> = 0.015), approaching those of the Sham group. Conclusions Radiological and histological analyses in a validated rat tibial nonunion model revealed that repeated PRP administration significantly improved bone repair. Although functional recovery was not significantly improved within six weeks, these findings support PRP as a biologically active and clinically promising adjunct for challenging cases of fracture nonunion.