effect of smoking on bone healing [combined experimental and clininical study]

The goal of this study was to assess effect of cigarette smoking on bone-healing after fracture both experimentally and clinically. Twenty-four adult male albino rats were randomly divided into control [8 rats] and experimental [16 rats] groups. Unilateral closed fracture was done in the left tibia of the experimental animals under general anaesthesia. The experimental group was divided into two equal subgroups. The first one was left under normal condition for four weeks. The second subgroup was exposed to daily intermittent cigarette smoke inhalation for the same period. At the appropriate date, all rats of control and experimental groups were sacrificed. Antero-posterior radiographs were taken to demonstrate degree of healing in both experimental subgroups. Histological examination was done to assess the degree of healing. On the other hand, during the period between 1[st] January to 31[th] December 2005, 73 patients with closed fracture tibias treated with interlocking nail in Tanta University hospitals, Egypt were included in this study and followed up after classification according to their smoking habits. Radiologically; four weeks post fracture, there was complete tibial healing in the smoke unexposed subgroup whereas the smoke exposed subgroup showed partial bone healing. Histologically; There is definite delayed healing in the group exposed to intermittent smoke inhalation. In the clinical study, it was found that there is significant difference in the mean duration of healing between the two groups. Likewise, there was a 69% delay in radiographic union in the smokers group. This study suggests that intermittent cigarette smoke inhalation delayes, but does not prevent bone healing after fracture so that smoking history should be considered in fracture patient