Study demonstrates negative effects of smoking on outcomes for ankle replacement
A study examining the effects of cigarette smoking on total ankle replacement (TAR) surgery found that active cigarette smokers had a significantly higher risk of wound complications and worse outcome scores compared with nonsmokers and former smokers.

The study, presented at the annual meeting of the American Orthopaedic Foot & Ankle Society (AOFAS) in Toronto by Alexander J. Lampley, MD, of Duke University, also found that tobacco cessation appeared to reverse the effects of smoking, potentially leading to perioperative complication rates and outcomes similar to those for nonsmokers.

The authors of the study retrospectively examined a consecutive series of 642 primary TAR patients with known smoking status as follows:

• 359 nonsmokers
• 34 active smokers
• 249 former smokers

Active smokers smoked about a pack a day on average, with an average history of 25.6 years of cigarette use and a cumulative smoking history of 25.1 years. Former smokers had an average cumulative 20 pack-year smoking history, and had quit smoking an average of 23.4 years prior to surgery.

The surgeries were performed at a single institution by four orthopaedic foot and ankle surgeons with extensive TAR experience. Indication for surgery was debilitating ankle pain with loss of function secondary to ankle arthritis that did not respond to conservative treatment. Several types of third-generation ankle replacement systems were used.

Study outcomes reviewed included perioperative complications—infection, wound breakdown, revision surgery, and nonrevision surgery—and patient-reported outcome scores, using the Short Form 36 Health Survey (SF-36), the AOFAS hindfoot score, and the Short Musculoskeletal Function Assessment (SMFA). Wound breakdown was defined as any wound issue that would require return to the operating room (Fig. 1), Dr. Lampley explained. It did not include delayed wound healing, nor any wound breakdown treated in clinic with local wound care.

Comparing perioperative complications in active smokers and nonsmokers, smokers had a statistically significant increased risk of wound breakdown (11.8 percent versus 3.9 percent with a hazard ratio [HR] of 3.08; P = 0.047). Increased rates of infection (HR 2.61; P = 0.392), revision surgery (HR 1.75; P = 0.47), and nonrevision surgery (HR 1.69; P = 0.172) were noted in the smokers, but the differences did not reach statistical significance. Similar findings have been published for patients undergoing total knee and total hip arthroplasty, Dr. Lampley said.

At 1- and 2-year follow-up, all groups showed improvement in outcome scores, compared with preoperative scores. However, active smokers had less improvement in outcome scores than nonsmokers. This difference was statistically significant for SF-36 and SMFA scores. No significant difference in outcome scores for nonsmokers versus former smokers was found. "The difference in outcome scores was especially noteworthy as the active smoker group, with a mean age of 52.9 years, was significantly younger than the nonsmoker group [mean age 61.8]," the authors observed.

Toxic effects
The association between cigarette smoking and perioperative wound complications is likely attributable to the toxic components smokers absorb systemically. Notably, nicotine has been shown to increase platelet adhesiveness, which leads to microvascular occlusion and decreased microperfusion, the authors noted. Nicotine has a vasoconstrictive effect, which, coupled with microvascular occlusion, can lead to tissue ischemia. Carbon monoxide blocks hemoglobin, thereby decreasing the oxygen available to healing tissues.

The authors also note that cigarette use increases blood levels of pro-inflammatory cytokines, which are "potent signalers of pain in the central nervous system." Tobacco use has been associated with osteoporosis, and smokers "may have worse pain at the bone-prosthesis interface because of their decreased bone mineral density," the authors observed.

Dr. Lampley said he and his coauthors conducted the study because "although the negative effects of tobacco use have been demonstrated in the hip and knee arthroplasty literature, no study has previously examined the effect of cigarette smoking on complications or functional outcome scores after total ankle arthroplasty.

"Overall, we expected cigarette smokers to have higher rates of complications, which was confirmed with our data analysis," he said. "We were less confident with our hypothesis that smokers would have worse functional outcome scores. Although a large body of evidence suggests tobacco use is associated with higher complication rates, there is little published data regarding the effects of tobacco use on functional outcome scores. In reviewing the literature, we came across studies that reported worse functional outcome scores in smokers after anterior cruciate ligament reconstruction and spine surgery."

Dr. Lampley said the findings correspond to those of a recent meta-analysis as well as to two randomized controlled trials that showed that a perioperative smoking cessation program reduced the rate of postoperative complications. The study findings, he concluded, highlight the importance of preoperative smoking cessation for better patient outcomes in TAR and "can be used to further educate patients on the need to quit smoking prior to total ankle arthroplasty." Ideally, the authors wrote, TAR should be delayed until smoking cessation is accomplished.

Finally, he noted, "Although our study demonstrated that former smokers had outcomes similar to nonsmokers, these findings may not be generalized for patients stopping cigarette use near the time of surgery. The wide range of time between quitting smoking and surgery—0.1 to 54.6 years—precluded us from calculating a 'minimum' time needed for former smokers to reverse the increased risk of wound breakdown and poorer functional outcomes. Future research aimed at answering this question would be helpful in planning operative timing after smoking cessation."

Dr. Lampley's coauthors of "Association of Cigarette Use and Complication Rates and Outcomes Following Total Ankle Arthroplasty" are Christopher E. Gross, MD; Cynthia L. Green, PhD; James K. DeOrio, MD; Mark E. Easley, MD; Samuel B. Adams, MD; Suhail Mithani, MD; and James A. Nunley II, MD.

The authors' disclosure information can be accessed at www.aaos.org/disclosure

Terry Stanton is the senior science writer for AAOS Now. He can be reached at tstanton@aaos.org

Bottom Line

• In a study comparing smokers and nonsmokers undergoing TAR procedures, smokers had a significantly higher rate of wound breakdown, and higher rates of revision surgery and infection (not statistically significant).
• Smokers had significantly less improvement in postoperative outcome scores for SF-36 and SMFA instruments, and the smoking group was significantly younger than the nonsmoking group.
• The findings demonstrate the importance of counseling patients about smoking cessation.
• Future research is warranted in regard to the minimum time interval after smoking cessation required to decrease its negative effect on outcomes.