Modifications of the paraspinous muscle flap: anatomy and clinical application

Soft-tissue defects of the back, particularly involving the paravertebral tissues, are generally covered with myocutaneous, muscle, or fasciocutaneous flaps. The case of a 64-year-old man with a paravertebral malignant fibrous histiocytoma is reported. To ensure adequately radical margins, the ipsilateral trapezius and latissimus dorsi muscles as well as the costal periosteum and the spinous processes were resected between T9 and T12. The resulting defect was covered with a pedicled latissimus dorsi flap and an island flap of the paravertebral muscles. Prompted by this case, we studied the blood supply of the paravertebral muscles in 10 cadavers. The vasculature was visualized after flushing with colored latex and microsurgical dissection. Another 4 specimens were subjected to angiography and tomography. In the majority of cases (8 of 10), three perforators emerging from the intercostal arteries were identified. These were found to communicate in a longitudinal and vertical direction. Before piercing the fascia, they ramified in three layers matching the layers of the paravertebral muscles. Since the intercostal arteries were shown to communicate through anastomoses of adequate caliber, the paravertebral muscles appear to be useful candidates for proximally or distally pedicled transposition or island flaps.