Mini-invasive thoracotomies may reduce chronic pain and pain-related functional impairment. The aims of part 2 of the study were to assess their incidence after posterolateral and axillary thoracotomies and to identify potential factors of chronic pain. Patients undergoing a posterolateral (79 patients) or axillary (79 patients) thoracotomy between July 2014 and November 2015 were analyzed in this prospective monocentric cohort study. At the 4-month assessment, more patients had chronic pain in the posterolateral group (60.8% vs 40.5%; p=0.017).  There was a significant difference between groups favoring the axillary group: less level of catastrophism (p=0.021) and less impact of pain on daily activities (globally, p=0.009; routine activities subscore, p=0.010, chosen activity subscore, p=0.030). According to a multinomial logistic model multivariable, three factors are associated with the presence of chronic pain: the presence of pain before surgery (OR=2.36, CI 95% [1.03-5.39]), a large posterolateral incision (OR=4.14 [1.25-13.72]) and the intensity of pain during mobilization of the ipsilateral shoulder at postoperative day 6 (OR=1.37 [1.10-1.70]). In conclusion, chronic pain is less frequent after an axillary approach than after a posterolateral one. Identified risk factors for chronic pain should lead to more aggressive management of preoperative and early postoperative pain and favor the mini-invasive approach.

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