Tobacco use has been associated with many illnesses including heart disease, blood vessel disease, and several forms of cancer. In addition' research has shown that skin wounds heal slower in people who smoke cigarettes. Now, there is also some evidence that bone heals slower in smokers than in nonsmokers.

Recently, Dr. George Cierny III and his colleagues studied the role of tobacco smoking in bone healing. The study, which was conducted at Emory University in Atlanta, revealed that bone formation during bone transports was much slower in patients who smoked than in patients who did not smoke

The researchers studied 29 patients who were being treated for a fractured tibia (shin bone) and who developed infection of the bone (osteomyelitis). Patients answered a questionnaire regarding their smoking history. Also, each patient had blood and urine tests to verify his or her exposure to nicotine and cotinine, which are contained in tobacco. The patients were divided into groups of nonsmokers, former smokers, and current smokers.

The infected bone was removed in all of the 29 patients. The physicians used the ilizarov external fixation device to allow new bone to form during bone transport.

The physicians took x-rays of the patients' legs at different times after the ilizarov apparatus was in place so they could assess the rate of healing. They found that the nonsmoking patients formed new bone much faster than the patients who continued to smoke during the study. The average length of time for a nonsmoker to form 1 cm of new bone was 69.6 days, compared with 89.4 days for the smokers. Based on this rate, if a patient needed to form 5 cm (2 inches) of new bone, it would take 10 months for a nonsmoker and 15 months for a smoker. Former smokers also healed slower. Based on their rate of healing, it would take 1 3.6 months for a former smoker to form 5 cm of new bone.

It is difficult to pinpoint the exact cause of the slower healing rate in smokers and former smokers. The are thousands of different chemical substances known to be harmful in cigarette smoke. Also, the effect of other types of tobacco products, such as snuff or smokeless tobacco, on the healing rate of soft tissue and bone is unknown.

One researcher at the University of California in San Francisco thinks nicotine may cause bone and soft tissue to heal slower in smoking patients. The nicotine in cigarette smoke reduces the amount of oxygen that reaches healing tissues. This lack of vital oxygen severely hampers the healing of all tissues, including broken bones.

During the past 20 years researchers have found more evidence that cigarette smoking causes serious health problems. Now researchers at Emory University and the University of California at San Francisco have linked cigarette smoking with delayed healing of bone.

Joseph A. Martino, M.D.