Does cessation of combustible cigarette and heated tobacco product smoking immediately following a fracture benefit fracture healing? In vivo and in vitro validation.

Combustible cigarette and heated tobacco products (HTPs), the two most frequently used tobacco products, negatively affect bone healing. However, whether smoking cessation following fracture benefits bone healing is unclear. Therefore, this study investigated the effect of smoking cessation immediately after surgery on reduced fracture healing induced by smoking. Smoking combustible cigarettes and heated tobacco products generates cigarette smoking extracts (CSE) (extracts from combustible cigarettes [cCSE] and from HTPs [hCSE], respectively). In vivo, CSEs were injected intraperitoneally into rat models for 3 weeks before femoral midshaft osteotomy and fixation. The rats were then divided into CSE continuation and cessation groups postoperatively. Micro-computed tomography (μCT) and biomechanical analyses were performed 6 weeks postoperatively to assess bone union at the fracture site. In vivo study showed μCT assessment also revealed significantly higher cortical bone mineral density (p = 0.013) and content (p = 0.013), and a higher bone union score (p = 0.046) at the fracture site in the cCSE cessation group than in the cCSE continuation group. Biomechanical assessment revealed that elasticity at the fracture site was significantly higher in the cCSE cessation group than in the cCSE continuation group (p = 0.041). These findings provide that smoking cessation, particularly of combustible cigarette, immediately after a fracture accelerates bone fracture healing and increases mechanical strength at the fracture site.