Objective: To investigate the perioperative management of wounds associated with secondary sternal osteomyelitis and/or mediastinitis after sternotomy, and to evaluate its clinical effects. Methods: This study was a retrospective observational study. From January 2017 to December 2022, 36 patients with wounds associated with secondary sternal osteomyelitis and/or mediastinitis after sternotomy who were conformed to the inclusion criteria were admitted to the Burn Center of PLA of the First Affiliated Hospital of Air Force Medical University, including 23 males and 13 females, aged 25 to 81 years. Preparation for surgery was made. For patients with suspected retrosternal mediastinal abscess cavity, all cancellous bone of the unhealed sternum was bitten off to fully expose the retrosternal mediastinum, remove the source of infection and granulation tissue, and to fill the sternum defect with flipped unilateral pectoralis major muscle. For patients who had no retrosternal mediastinal infection but had fresh granulation tissue in unhealed sternal wounds, the necrotic tissue and a small amount of necrotic sternum were palliatively removed, and bilateral pectoralis major muscles were advanced and abutted to cover the sternal defect. After the skin in the donor area was closed by tension-relieving suture, continuous vacuum sealing drainage was performed, and continuous even infusion and lavage were added 24 hours later. The thorax was fixed with an armor-like chest strap, the patients were guided to breathe abdominally, with both upper limbs fixed to the lateral chest wall using a surgical restraint strap. The bacterial culture results of wound exudation specimens on admission were recorded. The wound condition observed during operation, debridement method, muscle flap covering method, intraoperative bleeding volume, days of postoperative infusion and lavage, lavage solution volume and changes on each day, and postoperative complications and wound healing time were recorded. After discharge, the wound healing quality, thorax shape, and mobility functions of thorax and both upper limbs were evaluated during follow-up. The stability and closure of sternum were observed by computed tomography (CT) reexamination. Results: On admission, among 36 patients, 33 cases were positive and 3 cases were negative in bacterial culture results of wound exudation specimens. Intraoperative observation showed that 26 patients had no retrosternal mediastinal infection but had fresh granulation tissue in unhealed sternal wounds, palliative debridement was performed and bilateral pectoralis major muscles were advanced and abutted to cover the defect. In 10 patients with suspected retrosternal mediastinal abscess cavity, the local sternum was completely removed by bite and the defect was covered using flipped unilateral pectoralis major muscle. During the operation, one patient experienced an innominate vein rupture and bleeding of approximately 3 000 mL during mediastinal exploration, and the remaining patients experienced bleeding of 100-1 000 mL. Postoperative infusion and lavage were performed for 4-7 days, with a lavage solution volume of 3 500-4 500 mL/d. The lavage solution gradually changed from dark red to light red and finally clear. Except for 1 patient who had suture rupture caused by lifting the patient under the armpit during nursing on the 3rd day after surgery, the wounds of the other patients healed smoothly after surgery, and the wound healing time of all patients was 7-21 days. Follow-up for 3 to 9 months after discharge showed that the patient who had suture rupture caused by armpit lifting died due to multiple organ failure. In 1 patient, the armor-like chest strap was removed 2 weeks after surgery, and the shoulder joint movement was not restricted, resulting in local rupture of the suture, which healed after dressing change. The wounds of the remaining patients healed well, and they resumed their daily life. The local skin of patient's pectoralis major muscle defect was slightly sunken and lower than that of the contralateral thorax in the patients undergoing treatment of pectoralis major muscle inversion, while no obvious thoracic deformity was observed in patients undergoing treatment with pectoralis major muscle propulsion and abutment. The chest and upper limb movement in all patients were slightly limited or normal. CT reexamination results of 10 patients showed that the sternum was stable, the local sternum was closed or covered completely with no lacuna or defects. Conclusions: Once the wound associated with secondary sternal osteomyelitis and/or mediastinitis after sternotomy is formed, individualized and precise debridement should be performed as soon as possible, different transfer ways of pectoralis major muscle flap should be chosen to cover the defect, and postoperative continuous infusion and lavage together with strict thorax and shoulder joint restraint and immobilization should be performed. This treatment strategy can ensure good wound healing without affecting the shape and function of the donor area.