Effect of Cigarette Smoking on the Clinical Outcomes of ACL Reconstruction.

BACKGROUND: We compared the clinical outcomes of nonsmokers, current smokers, and former smokers following reconstruction of the anterior cruciate ligament (ACL) and investigated the association between the amount of smoking and outcomes following ACL reconstruction.

METHODS: We retrospectively reviewed the records of 251 patients who underwent unilateral ACL reconstruction with use of bone-patellar tendon-bone autograft between January 2002 and August 2009. Patients were divided into three groups according to smoking history: Group 1, nonsmokers; Group 2, current smokers; and Group 3, former smokers. Preoperative values and twenty-four-month postoperative findings were compared among the groups. The stability of the ACL was evaluated with use of the Lachman test and the pivot-shift test, and anterior translation was tested with a KT2000 arthrometer. Functional outcomes were assessed on the basis of the Lysholm score and the International Knee Documentation Committee (IKDC) subjective score and objective grade.

RESULTS: The three groups differed significantly in terms of postoperative knee translation, Lysholm score, and IKDC subjective score. The mean side-to-side difference in anterior translation (and standard deviation) was 2.08 ± 1.08 mm in Group 1 (nonsmokers), 2.65 ± 1.31 mm in Group 2 (smokers), and 2.15 ± 1.05 mm in Group 3 (former smokers) (p = 0.003). The mean Lysholm score was 90.5 ± 6.5 in Group 1, 86.0 ± 7.1 in Group 2, and 89.8 ± 6.3 in Group 3 (p < 0.001). The mean IKDC subjective score was 89.3 ± 5.1 in Group 1, 84.9 ± 7.5 in Group 2, and 88.5 ± 4.2 in Group 3 (p < 0.001). However, the difference in the IKDC subjective score among the three groups did not demonstrate a minimal clinically important difference. A dose-dependent association was noted between pack-years of exposure and postoperative anterior translation (estimate, 0.039; p = 0.015) and IKDC objective grade (odds ratio, 1.083; p = 0.002). A comparison of the three subgroups of smokers showed a significant difference in anterior translation (a mean side-to-side difference in anterior translation of 2.31 ± 1.17 mm for the light smokers, 2.60 ± 1.14 mm for the moderate smokers, and 3.29 ± 1.55 mm for the heavy smokers; p = 0.038). The three subgroups also differed significantly in terms of the proportion of cases by IKDC objective grade; among the light smokers, thirteen (42%) were grade A, fifteen (48%) were grade B, two (7%) were grade C, and one (3%) was grade D; among the moderate smokers, seven (35%) were grade A, eight (40%) were grade B, four (20%) were grade C, and one (5%) was grade D; and among the heavy smokers, one (6%) was grade A, eight (44%) were grade B, eight (44%) were grade C, and one (6%) was grade D (p = 0.013).

CONCLUSIONS: Cigarette smoking appeared to have a negative effect on subjective and objective outcomes of ACL reconstruction, and heavy smokers showed greater knee instability. Patients who had stopped smoking at least one month prior to ACL reconstruction had no significant difference in outcomes compared with patients who had never smoked.

LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.