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

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.