The Effect of Cigarette Smoking on the Development of Osteoporosis and Related Fractures

, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, Pa.

Disclosures

Medscape General Medicine. 1999;1(3) 

In This Article

Clinical Implications: Effect of Cigarette Smoking on Fracture and Fracture Healing

Older men and women who have smoked for many years are more likely to sustain fractures after minimal trauma than are nonsmokers. Fracture occurs most frequently at the hip, wrist, and spine, but any bone with low bone mineral density (BMD) is more susceptible to fracture.

The two major risk factors for osteoporotic fractures are low BMD and a propensity for falling in smokers known to have poorer neuromuscular function compared with nonsmokers.[35] Even after taking into account comorbid conditions, smokers are weaker and have poorer balance, gait, and integrated physical function. Currently, there is no evidence that smoking alone increases the frequency of falling in the elderly or the likelihood of injury after falling.[36]

Older men and women who smoke cigarettes have significantly lower BMD than those who do not. Cadaveric studies show that if BMD decreases by 10% then bone strength shows a three-fold decrease.[37,38] Thus, it is reasonable to expect an increased incidence of fractures among smokers on the basis of BMD level alone.

Hip Fractures

Older smokers have a 20% to 100% increased likelihood of fracturing their hips.[11] This excess risk increases with age: 0% at age 50 years, 17% at age 60 years, 41% at age 70 years, 71% at age 80 years, and 108% at age 90 years.[39] In fact, it is estimated that 1 in 8 hip fractures in women is directly attributable to smoking cigarettes.[39] In one prospective study of hip fractures occurring throughout 4.1 years in a large group of elderly women, the age-adjusted incidence of fractures was more than double among the women who were currently smoking compared with those who had never smoked.[40] Former smokers have an excess risk of fracture that is intermediate between that of current and never-smokers.[40,41,42,43] The risk of hip fracture among women is related to the number of cigarettes smoked each day.[19,42,43] Although there is less information available on the excess risk of hip fracture in elderly men who smoke, all available evidence indicates that it is similar to that in women.[20,41]

The effect of smoking on hip fracture is most evident among thin, elderly women. Forsen and colleagues[20] reported that among female smokers older than 50 years, the excess risk of hip fracture was 50%. Among the thin female smokers (body mass index <20 kg/m2), the risk increased three-fold relative to nonsmokers. Thin male smokers had an 80% increased risk. Williams and colleagues[7] found a similar effect of smoking among thin women, particularly among those who had never used estrogen.

The Nurses Health Study[21] found no relationship between smoking and risk of hip fracture among the almost 97,000 middle-aged nurses studied. However, the incidence of hip fractures among women aged 35 to 59 years is relatively low, which may explain the apparent lack of effect of smoking in this study.

Wrist Fractures

Evidence regarding the relationship between cigarette smoking and wrist fractures is limited. Among thin women who had never taken postmenopausal estrogen, the risk of forearm fracture was found to be more than five-fold greater (relative risk [RR], 5.4; 95% confidence interval, 2.5-11.3) among smokers than among never-smokers.[7] Estrogen use was highly protective in this group of smokers. Among the women who had used estrogen replacement therapy, the risk of fracture was not associated with either cigarette use or body weight. Three other studies[21,30,44] have failed to show a relationship between smoking and wrist fractures. Jensen[30] believes that the primary determinant of fracture risk is low body weight. Since smokers tend to be thinner than nonsmokers and therefore have lower BMD, they may be predisposed to fractures after a minor fall.

Spine Fractures

Long-term cigarette use is a well-established risk factor for a variety of back problems, including back pain, disk abnormalities, and other degenerative spinal conditions.[45,46,47] A study of female twins established that smokers have approximately 10% lower spinal BMD by the time they reach menopause than do nonsmokers.[14] It also appears that by the age of 60 years, the risk for vertebral fracture is almost double among both men and women who smoke.[8,48]

In a case-control study of men aged 44 to 83 years with vertebral fractures secondary to spinal osteoporosis, the RR (estimated from the odds ratio) for fracture among smokers was 2.3 (P = .01). The use of alcohol (average 2.8 oz/d among the cases) also increased the risk for fracture (RR = 2.4, P = .002). Obesity (defined as body weight at least 20% greater than recommended based on standardized tables) was a protective influence (RR = 0.3, P <.001). The results, however, were highly dependent on the age of the patients. Neither smoking nor drinking was associated with an increased risk of fracture in those younger than 60 years. Small increases in risk were seen among those aged 60 to 69 years, whereas the risk among nonobese men 70 years and older with no other major underlying disease who smoked and used alcohol was 20.2 (P <.05). The obese men in this age group who smoked and drank alcohol had approximately a seven-fold increased risk of fracture compared with the nonsmoker, nondrinker group (Figure 2).[8]

Figure 2. Relative risk of spinal osteoporosis with spinal fracture in men (data derived from Seeman et al. [8])

Fracture Healing and Patient Outcomes

Smokers are not only more susceptible to fracture but are also more likely to have recurrent fractures.[18] Healing of fractures is delayed in smokers,[22,23,24,26] the maturation of the regenerating bone is reported to be abnormal,[29] and nonunion or malunion is more frequent.[25,27,28,29] Fusion of the vertebral bodies after surgery, particularly in the lumbar spine, not only occurs more slowly in smokers but is also three to five times more likely to fail.[49,50,51,52] Fusion rates are particularly low in smokers when allograft rather than autograft bone is used as the fusion material. It has been suggested, therefore, that only autograft bone be used in fusion procedures when the patient is a heavy smoker.[4]

Smokers assess their outcomes after surgery much less favorably than do nonsmokers.[53,54] Hilibrand and coworkers[54] found that 89% of nonsmokers who had undergone multilevel anterior cervical decompressions with autogenous grafting rated their outcome as good or excellent versus 76% of the smokers. Among patients undergoing repair of a pseudoarthrosis of the lumbar spine, the scores on the patient outcome questionnaire were inversely related to the number of pack-years of smoking (P = .02).[53]

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