The posterior midline approach used in spinal surgery has been associated with a significant rate of wound dehiscence. This study investigates anatomical study of the arterial supply of the cervical and thoracic spinal muscles and overlying skin at each vertebral level. It aimed to provide possible anatomical basis for such wound complications.

A dissection and angiographic study was undertaken on 8 cadaveric neck and posterior torso from 6 embalmed and 2 fresh human cadavers. Harvested cadavers were warmed and hydrogen peroxide was injected into the major arteries. Lead oxide contrast mixture was injected in stepwise manner into the subclavian and posterior intercostal arteries of each specimen. Specimens were subsequently cross-sectioned at each vertebral level and bones elevated from the soft tissue. Radiographs were taken at each stage of this process and analysed.

The cervical paraspinal muscles were supplied by the deep cervical arteries, transverse cervical arteries and vertebral arteries. The thoracic paraspinal muscles were supplied by the superior intercostal arteries, transverse cervical arteries and posterior intercostal arteries. In the thoracic region, two small vessels provide the longitudinal connection between the segmental arteries and in the cervical region, deep cervical arteries provide such connection from C3 to C6. The arterial vessels supplying the paraspinal muscles on the left and right side anastomose with each other, posterior to the spinous processes in all vertebral levels. At cervical vertebral levels, source arteries travel near the surgical field and are not routinely cauterised; Haematoma is postulated to be the cause of wound complications. At thoracic levels, source arteries travel in the surgical field and tissue ischemia is a contributing factor to wound complications, especially in operations over extensive levels.

Post-operative wound complications is a multi-factorial clinical problem, the anatomical findings in this study provide possible explanations for wound dehiscence in the posterior midline approach. It is postulated that drain tubes may reduce the incidence of haematoma in the cervical level.

Shoulder girdles of 20 cadavers (68–94yrs) were harvested. The anterior (ACHA) and posterior circumflex humeral arteries (PCHA) were injected with ink and the extra and intraosseous courses of the dyed vasculature dissected through the soft tissues and bone to the osteotendinous junctions of the rotator cuff. The ink injection and bone dissection method was newly developed for the study.

Rates of cross-over at the osteotendinous juntion were 75% in the supraspinatus, 67% in subscapularis, 33% in infraspinatus and 20% in teres minor. The supraspinatus and subscapularis insertions were vascularised by the arcuate artery, a branch of the ACHA. The insertions of the infraspinatus and teres minor were supplied by an unnamed terminal branch of the PCHA.

The insertions of the rotator cuff receive an arterial supply across their OTJ's in 50% of cases. This may explain observed rates of AVN in comminuted proximal humeral fractures. The terminal branch of the PCHA supplying the infraspinatus and teres minor insertions was named the “Posterolateral Artery”. Finally, the new method employed for this study which allowed for direct visualisation of intraosseous vasculature, will enhance our understanding of skeletal vascular anatomy and have clinical applications in orthopaedic and reconstructive surgery.