3.13.1 Bone density, osteoporosis and the risk of fractures
Osteoporosis is a skeletal disease characterised by low bone mass density (BMD) and deterioration of bone, with a consequential increase in bone fragility and risk of fractures. The diagnosis of osteoporosis is based on low BMD. The most common osteoporotic fractures are of the hip, lumbar spine and wrist. Hip fractures are the most severe.1
Osteoporosis is common and is associated with older age and female gender. Women aged 50 have almost a 50% lifetime risk of an osteoporotic fracture.1 In Australia, there were more than 16 000 osteoporotic hip fractures in 2006–2007; about three-quarters were in women whose average age was 83 years.2
Smoking decreases BMD in the middle and later years of life. The 2004 US Surgeon General's report concluded that smoking causes low BMD in postmenopausal women.3 BMD decreases by about an additional 2% per year in smokers compared with non-smokers, leading to a difference of about 6% by age 80.4
Although the Surgeon General concluded only that smoking 'may' cause low BMD in older men,3 a meta-analysis of the effect of smoking on BMD that included data from more than 40 000 subjects found that smoking has a more deleterious effect on bone mass for men than women.5 This meta-analysis also found that the effect of smoking on BMD is dose dependent. The more that people smoked—reflected in higher pack-years, cigarettes per day or number of years smoked—the lower their bone mass.
Both the meta-analysis and the Surgeon General's report found insufficient evidence that smoking lowers BMD in younger women and younger men.3, 5 The meta-analysis suggested that this is because the total exposure to smoking in young adults is insufficient to produce discernible decrements in BMD, and cited several studies that demonstrate a significant negative impact of smoking on BMD in young adults who are heavy smokers.5
Smoking cessation may slow or even partially reverse bone mass loss, but more research is needed to evaluate this issue.5
Because smoking lowers BMD and increases the risk of osteoporosis, it would be expected to increase the risk of bone fractures. Projections from the meta-analysis of the effect of cigarette smoking on BMD suggest that smoking will increase the lifetime risk of a vertebral fracture by 13% in women and 32% in men. For hip fractures, smoking-attributable increases in risk were projected to be 31% in women and 40% in men.5 The Surgeon General3 and two meta-analyses of studies investigating fracture risk in smokers have confirmed this effect.4, 6 The 2004 Surgeon General's report concluded that smoking increases the risk of hip fractures, but found that there was inadequate evidence at that time to reach the same conclusion about smoking and fractures of other bones.3 The first meta-analysis of fracture risk, published in 1997, found that female smokers had a 41% increase in hip fractures at age 70 years.4 The most recent fracture meta-analysis, published in 2005, included data for almost 60 000 people and reported a 25% increase in risk of any fracture, and an 84% increase in the risk of hip fracture, associated with smoking.6
A number of mechanisms may contribute to the loss of BMD in later life consequential to smoking. Nicotine and cadmium in cigarette smoke may have a direct effect on bone cells, and smokers' bone density could also be impaired through lower absorption of calcium and vitamin D, and altered metabolism of some other hormones. Smoking also affects oestrogen levels and the effectiveness of hormonal replacement therapy. Smokers tend to have a lower body weight and be less physically active than non-smokers. Both of these factors adversely affect BMD. Smokers also reach menopause earlier, on average, thereby extending the postmenopausal period of accelerated bone mineral loss.3
Data from the 2005 meta-analysis of smoking and fracture risk suggest that smoking may also increase the risk of fractures independently of its effect on BMD.6 In this meta-analysis, there was still a 12% increase in the risk of any fracture associated with smoking, after adjustment for age, BMD and body mass index, and this increase was just statistically significant. The authors suggested that this effect could be due to the poorer balance and poorer physical function that has been reported in smokers (see Chapter 3, Section 3.13.4).7
3.13.2 Delayed bone union
There is increasing evidence from both observational and experimental studies that smoking delays bone healing (union) after fracture or surgery.8-11 After elective foot surgery, for example, a 42% increase in the time to bone healing has been reported.12 Smoking has been found to increase the chance of non-union after spinal fusion surgery13 and to worsen outcomes.14
3.13.3 Back pain
There have been suggestions in the medical and health economic literature that smoking causes low back pain and increases the incidence of sick leave due to back pain.15, 16 A meta-analysis of all studies published until February 2009 has confirmed an increase in low back pain in current and former smokers.17 The association was stronger in adolescents than adults and was more pronounced for chronic back pain and severe back pain. The authors of the meta-analysis speculated that the effect could be due to reduced perfusion of intervertebral discs.
An analysis of the link between smoking and low back pain in more than 70 000 Canadians was published in 2010.18 Smoking increased the likelihood that survey participants of all ages would have lower back pain, after adjustment for body mass index, level of activity and other factors that could have explained the association. The risk of having lower back pain was about 80% higher in daily smokers aged 20 to 29 years. The excess risk decreased with age but was still statistically significant at all ages.
3.13.4 Other musculoskeletal problems
Smoking might increase joint cartilage loss,19 and has been reported to increase the risk of tears of the rotator cuff (the muscles and tendons that stabilise the shoulder),20 but further research is needed before these adverse effects could be regarded as confirmed.
A study of almost 10 000 women aged 65 years and over in the US found that smokers had poorer physical function than non-smokers, as measured by tests of muscle strength, agility, co-ordination, gait and balance, and self-reported physical status.7 The researchers likened the poorer physical function to a hastening of ageing by about five years, and suggested that the effect may be due to the poorer vascular function consequential to smoking.
A 2011 meta-analysis of 48 studies, including more than 500 000 participants, investigated the association between smoking and osteoarthritis.21 The analysis found that the protective effect of smoking observed in some studies, but not others, is likely to be false and may be caused by selection bias. The effect was seen in hospital-based case-control studies (where the control subjects are more likely to have smoking-related conditions), but not in community-based case-control studies, cohort studies or cross-sectional studies.
Relevant news and research
For recent news items and research on this topic, click here.(Last updated July 2020)
1. Johnell O and Kanis J. Epidemiology of osteoporotic fractures. Osteoporosis International 2005;16 (suppl. 2):S3–S7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15365697
2. Australian Institute of Health and Welfare. The problem of osteoporotic hip fracture in Australia. AIHW bulletin no. 76. Cat. no. AUS 121. Canberra: AIHW, 2010. Available from: http://www.aihw.gov.au/publications/index.cfm/title/10695
3. US Department of Health and Human Services. The health consequences of smoking: a report of the Surgeon General. Atlanta, Georgia: US Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2004. Available from: http://www.cdc.gov/tobacco/data_statistics/sgr/index.htm
4. Law MR and Hackshaw AK. A meta-analysis of cigarette smoking, bone mineral density and risk of hip fracture: recognition of a major effect. British Medical Journal 1997;315(7112):841–6. Available from: http://pubmedcentralcanada.ca/picrender.cgi?artid=607368&blobtype=pdf
5. Ward KD and Klesges RC. A meta-analysis of the effects of cigarette smoking on bone mineral density. Calcified Tissue International 2001;68(5):259–70. Available from: http://www.ncbi.nlm.nih.gov/pubmed/11683532
6. Kanis JA, Johnell O, Oden A, Johansson H, De Laet C, Eisman JA, et al. Smoking and fracture risk: a meta-analysis. Osteoporosis International 2005;16(2):155–62. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15175845
7. Nelson H, Nevitt M, Scott J, Stone K, Cummings S et al. Smoking, alcohol, and neuromuscular and physical function of older women. Study of Osteoporotic Fractures Research Group. Journal of the American Medical Association 1994;272:1825-31. Available from: http://jama.ama-assn.org/content/272/23/1825.short
8. Adams C, Keating J and Court-Brown C. Cigarette smoking and open tibial fractures. Injury: International Journal of the Care of the Injured 2001;32(1):61–5. Available from: http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6T78-426XWS4-F-1&_cdi=5052&_user=559483&_orig=search&_coverDate=01%2F31%2F2001&_sk=999679998&view=c&wchp=dGLzVlz-zSkzS&md5=aca882f55aa98c3089be60973580d6db&ie=/sdarticle.pdf
9. Al-Mukhtar SA. The effect of cigarette smoking on bone healing in elderly individuals with Colle's fracture. Tobacco Use Insights 2010;3:17–22. Available from: http://www.la-press.com/the-effect-of-cigarette-smoking-on-bone-healing-in-elderly-individuals-article-a2225
10. Schmitz MA, Finnegan M, Natarajan R and Champine J. Effect of smoking on tibial shaft fracture healing. Clinical Orthopaedics and Related Research 1999;365(0):184–200. Available from: http://c-orthopaedicpractice.com/pt/re/cop/abstract.00003086-199908000-00024.htm;jsessionid=LRLpGVMGVtQZltYTCh9ytZqFMyFbjyycdnxDWlGFkd2zXQy7Kt42!383905440!181195628!8091!-1
11. Sloan A, Hussain I, Maqsood M, Eremin O and El-Sheemy M. The effects of smoking on fracture healing. Surgeon 2010;8(2):111–6. Available from: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=20303894
12. Krannitz K, Fong H, Fallat L and Kish J. The effect of cigarette smoking on radiographic bone healing after elective foot surgery. Journal of Foot and Ankle Surgery 2009;48(5):525–7. Available from: http://www.jfas.org/article/S1067-2516%2809%2900193-8/abstract
13. Andersen T, Christensen FB, Laursen M, Hoy K, Hansen ES and Bunger C. Smoking as a predictor of negative outcome in lumbar spinal fusion. Spine 2001;26(23):2623–8. Available from: http://www.spinejournal.com/pt/re/spine/abstract.00007632-200112010-00018.htm;jsessionid=LHnXqKMVqBDB159Kz1XGhm88nJsNSJb4WPy68Jh65qShJsLnb3l1!1629792715!181195629!8091!-1
14. Luca A, Mannion A and Grob D. Should smoking habit dictate the fusion technique? European Spine Journal 2010;20(4):629–34. Available from: http://www.springerlink.com/content/42nx4p40390121t8/fulltext.html
15. Alkherayf F and Agbi C. Cigarette smoking and chronic low back pain in the adult population. Clinical and Investigative Medicine 2009;32(5):e360–7. Available from: http://cimonline.ca/index.php/cim/article/view/6924
16. Skillgate E, Vingard E, Josephson M, Holm L and Alfredsson L. Is smoking and alcohol consumption associated with long-term sick leave due to unspecific back or neck pain among employees in the public sector? Results of a three-year follow-up cohort study. Journal of Rehabilitation Medicine 2009;41(7):550–6. Available from: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=19543666
17. Shiri R, Karppinen J, Leino-Arjas P, Solovieva S and Viikari-Juntura E. The association between smoking and low back pain: a meta-analysis. American Journal of Medicine 2010;123(1):87 e7–35 Available from: http://aje.oxfordjournals.org/cgi/content/full/171/2/135
18. Alkherayf F, Wai EK, Tsai EC and Agbi C. Daily smoking and lower back pain in adult Canadians: the Canadian Community Health Survey. Journal of Pain Research 2010;3:155–60. Available from: http://pubmedcentralcanada.ca/picrender.cgi?artid=1768844&blobtype=pdf
19. Davies-Tuck M, Wluka A, Forbes A, Wang Y, English D, Giles G, et al. Smoking is associated with increased cartilage loss and persistence of bone marrow lesions over 2 years in community-based individuals. Rheumatology (Oxford) 2009;48(10):1227–31. Available from: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=19696062
20. Baumgarten KM, Gerlach D, Galatz LM, Teefey SA, Middleton WD, Ditsios K and, Yamaquchi K. Cigarette smoking increases the risk for rotator cuff tears. Clinical Orthopaedics and Related Research 2010;468(6):1534–41. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19283436
21. Hui M, Doherty M and Zhang W. Does smoking protect against osteoarthritis? Meta-analysis of observational studies. Annals of the Rheumatic Diseases 2011;[Epub ahead of print] Available from: http://www.ncbi.nlm.nih.gov/pubmed/21474488