The influence of smoking and alcohol on bone healing: Systematic review and meta-analysis of non-pathological fractures

BACKGROUND: We aimed to comprehensively evaluate the associations between (i) smoking, (ii) preoperative smoking cessation time, (iii) nicotine replacement therapy (NRT), (iv) vaping, and (v) alcohol consumption and non-pathological fracture healing in adult patients. We also assessed the impacts of preoperative smoking cessation time, NRT, and vaping on wound healing and wound complications after any sort of surgery. METHODS: We searched the MEDLINE, Embase, Cochrane CENTRAL, CINAHL, and AMED electronic databases from their inceptions until August 9th, 2021. Primary outcomes included delayed union rate, nonunion rate, and time to union. A random effects model was used. (Protocol registration: PROSPERO—CRD42019131454). FINDINGS: One hundred and twenty-two studies with 417,767 patients were eligible for the systematic review and 71 of the studies with 39,920 patients were eligible for the meta-analysis. After non-pathological fracture treatment, the nonunion rate was significantly greater in the smoker group than in the non-smoker group (odds ratio [OR], 2·50, 95% confidence interval [1·73–3·61]); additionally, there was no significant difference in the nonunion rate (OR, 0·97 [0·40–2·38]) between the alcohol drinker group and the non-drinker group. The rate of wound infection after surgery was significantly reduced in the smoking cessation group (≥four weeks before surgery) compared to the continuous smoker group (OR, 0·37 [0·16–0·89]). INTERPRETATION: Smoking is associated with higher rates of nonunion and deep surgical site infection after non-pathological fracture treatment. Smoking cessation (≥four weeks before surgery) is associated with a decreased rate of postoperative wound infection. FUNDING: The China Scholarship Council (no. 201809120013).