The Influence of Smoking on Healing of Scaphoid Non-union after a Vascularized Pedicle Bone Flap Operation: A Review and Meta-analysis.

Background: The purpose of this study is to compare the vascularized bone flaps (VBF) that are used in operations for scaphoid non-union in smokers and non-smokers and to scrutinize if the better biological potential of the VBFs can counteract the negative influence of smoking on healing. Materials and Methods: Our study included articles published until 2016, with scaphoid non-union patients who were operated on with a VBF or a VBG. Results: Eighteen articles met eligibility criteria with 335 non-smokers and 136 smokers totally. Healing of the scaphoid non-union was significantly more probable in the non-smoking group (OR=5.54, p<0.001). Patients with avascular necrosis in the proximal pole of the scaphoid (AVNPP) and non-AVNPP showed that non-smoking favors a better healing rate in both of these subgroups (p<0.001 and p<0.001, respectively). Non-smokers have 11 times and the non-AVNPP patient's 7.7 times greater probability of healing of the non-union. Meta-analysis of the data for time for healing showed a longer time in the smokers' group by 2.46 weeks, though non-statistically significant. The analysis could not prove that smoking is a predisposing factor for the development of AVNPP (spearman=0.094, p<0.05). Despite that, preoperative smoking cessation proved to be an inadequate healing moderator (OR=3.5, p=0.268). Finally, VBFs showed a significantly better healing rate compared with nVBGs in smokers (p=0.001). Conclusions: A hand surgeon should always take into consideration that smoking negatively influences the healing potential of a scaphoid non-union despite the theoretically superior biological background that VBFs offer. In patients who refuse to quit smoking, a VBF may be considered a better choice than a conventional graft.