Abstract
Although adverse effects of smoking on bone health are all well known, data on how smoking interacts with cartilage structure in otherwise healthy individuals remains conflicting. Here, we ascertain the effects of cigarette smoking on sonoelastographic properties of distal femoral cartilage in asymptomatic adults. Demographic characteristics and smoking habits (packets/year) of healthy volunteers were recorded. Medial, intercondylar, and lateral distal femoral cartilage thicknesses and strain ratios on the dominant extremity were measured with ultrasonography (US) and real time US elastography. A total of 88 subjects (71 M, 17 F; aged 18–56 years, N = 43 smokers and N = 45 nonsmokers) were evaluated. Mean amount of cigarette smoking was 10.3 ± 8.9 (1–45) packets/year. Medial, intercondylar and lateral cartilage were thicker in smokers than nonsmokers (p = 0.002, p = 0.017, and p = 0.004, respectively). Medial distal femoral cartilage strain ratio was lower in smokers (p = 0.003). The amount of smoking was positively correlated with cartilage thicknesses and negatively correlated with medial cartilage strain ratios (p < 0.05). Femoral cartilage is thicker in smokers but has less strain ratio representing harder cartilage on the medial side. Future studies are needed to understand how these structural changes in the knee cartilage should be interpreted with regard to the development of knee osteoarthritis in smokers.
Highlights
The relationship between cigarette smoking and chronic musculoskeletal system disorders is a well-known entity in the literature [1,2]
High intraobserver reliability was detected for both distal femoral cartilage thickness and strain ratio measurements (Table 2)
While cartilage thicknesses were higher in the smoking group at three sites, only the medial cartilage strain ratio measurements were found to be lower in the smoking group
Summary
The relationship between cigarette smoking and chronic musculoskeletal system disorders (e.g., degenerative disc disease) is a well-known entity in the literature [1,2]. An inverse correlation has been reported between smoking and knee osteoarthritis, the effects of smoking on knee cartilage remains conflicting [3,4]. While some research suggests protective effects of smoking on osteoarthritis [4,5], others propose that smoking increases cartilage destruction [6]. Proposed mechanisms for the protective effect of nicotine on cartilage in an early osteoarthritis rat model were reduction of the serum level of TNF-α, reduction of the expression of TNF-α in the synovial tissue, and increase in the expression of α7nAChR in the synovial tissue [7]. It has been shown that smoking and nicotine delay revascularization of bone grafts, Int. J. Public Health 2016, 13, 434; doi:10.3390/ijerph13040434 www.mdpi.com/journal/ijerph
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