6.1.1 Principal Indications

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  Retropleural abscess in spondylitis

  
  
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  Biopsy

  
  
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  Tumors

  
  
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  Vertebral body fractures

6.1.2 Choice of Side of Approach

Approach is possible from both sides and depends on the site of the lesion.

6.1.3 Positioning and Incision

The operation may be performed with the patient in the prone or semilateral position. For exposure of the vertebral bodies alone, the semilateral position affords a better view toward the anterior direction. For the approach to the upper region of the thoracic spine, the arm on the affected side is maximally abducted to move the scapula as far away from the midline as possible ( Fig. 6.1 ).

Two types of skin incision are possible:

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  A straight paramedian incision about three fingerbreadths lateral to the spinous processes.

  
  
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  A T-shaped incision, which provides a better overview.

The transverse portion of the incision is at the level of the vertebra to be exposed (intraoperative markings are made by means of image converter or X-ray), while the longitudinal incision is made over the tips of the spinous processes and is approximately 15 cm long. Transection of the skin and subcutaneous tissue is followed by mobilization of the two skin flaps in the cranial and caudal directions. The superficial muscular layer (trapezius) is divided transversely ( Fig. 6.2 ). Using a diathermy scalpel, the intrinsic muscles of the back are now detached near the bone from the spinous processes, in keeping with the skin incision. Cranial and caudal to the transverse incision, the intrinsic muscles of the back are dissected free from the vertebral arches and transverse processes with a raspatory. The longissimus muscle is then transversely dissected and retracted upward and downward ( Fig. 6.3 ). The rib leading to the diseased vertebral body is thus identified.

The periosteum over this rib is split with cutting diathermy and carefully retracted with the raspatory. To begin with, the inferior border of the rib is exposed subperiosteally from lateral to medial. The upper border of the rib is exposed subperiosteally by dissecting from medial to lateral until the rib has been exposed subperiosteally over its entire circumference. Now a rib raspatory is used to continue the subperiosteal exposure laterally (8–10 cm) until the desired width of exposure has been obtained. The subperiosteal exposure in the medial direction extends to the costotransverse joint. Using rib shears, the rib is first transected laterally, the costotransverse joint is then opened with a scalpel, and the transverse process is exposed subperiosteally as far as the lamina. The transverse process may then be separated at its base with a narrow chisel and removed with rongeurs. The rib, already laterally detached, is lifted out of the wound area, and the periosteum underlying the rib is now carefully stripped with a raspatory as far as the costovertebral joint, sparing the neurovascular bundle caudal to the rib. Removal of the rib is accomplished by rotary motions on the rib and simultaneous retraction of the costovertebral joint capsule. Careless manipulation can lead to bleeding from the segmental vessels. Generally, three ribs are resected.

6.1.4 Exposure of the Vertebrae

The endothoracic fascia underlying the costal periosteum and the parietal pleura are carefully retracted from the anterior aspect of the vertebral bodies and intervertebral disks with cotton applicators, preserving the neurovascular bundles. The remains of the intercostal muscles lying between the resected ribs are dissected free from the segmental vessels ( Fig. 6.4 ). If necessary, the intercostal vessels may be ligated and transected anterior to the vertebral body, but the segmental nerves should be preserved if possible as, beginning at T6, they supply the abdominal muscles. After retraction of the parietal pleura from the anterior aspect of the vertebral bodies, flexible spatulas may be introduced so that two to three vertebral bodies are revealed laterally from behind ( Fig. 6.5 ).

6.1.5 Wound Closure

Before wound closure, positive pressure breathing should be employed to make certain that the parietal pleura has not been injured. If it has, a suction drain must be introduced. Wound closure is effected by reapproximation, in layers, of the divided muscles.

6.1.6 Note

Costotransversectomy was formerly considered to be the standard approach, particularly for the surgical treatment of tuberculous spondylitis. This approach has nowadays been largely supplanted by thoracotomy, which provides a better overview. Costotransversectomy is indicated, above all, when thoracotomy is precluded for medical or technical reasons, or when tumors involving both posterior vertebral structures and the vertebral body have to be resected in a single session. This approach has also been described for the internal fixation of vertebral fractures when anterior decompression of the vertebral canal is required at the same time.

6.2.1 Principal Indications

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  Scoliosis

  
  
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  Kyphosis

  
  
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  Fractures

  
  
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  Tumors

6.2.2 Positioning and Incision

The patient is placed prone with bolsters under the chest and under both iliac crests, or is placed on special supports, for example a Relton-Hall frame ( Fig. 6.6 ). Care should be taken not to compress the abdomen, so that venous congestion and hence increased venous hemorrhage during the operation may be prevented. A straight midline incision is made, even in scoliosis. If fusion is to be performed, the incision should be one to two segments longer than the intended length of fusion ( Fig. 6.7 ). Subsequently, the subcutaneous tissue is dissected as far as the fascia, and wound retractors are inserted.

6.2.3 Exposure of the Thoracic Spine

In children and adolescents, the cartilaginous spinous process apophyses are split in the midline in longitudinal direction, together with the interspinal ligaments ( Fig. 6.8 ). The apophyses with the adhering periosteum can easily be retracted with a raspatory to the base of the spinous processes or to the vertebral arches. In adult patients, the fascia has to be detached with a diathermy scalpel near the bone on both sides of the spinous process. Retraction of the muscle in operations for scoliosis is usually begun on the side of the concavity ( Fig. 6.9 ). The dissection is carried out from caudal to cranial.

The exposure should be strictly subperiosteal so that the neurovascular supply of the muscles may be spared and hemorrhage avoided ( Fig. 6.10 ).

There may be severe bleeding from the posterior external vertebral venous plexus ( Fig. 6.11 ), which must be stopped by electrocoagulation or tamponade.

The subperiosteal exposure is continued laterally as far as the ends of the transverse processes. When the concave side has been exposed, it is tamponaded with gauze swabs, and the same procedure is then followed on the contralateral side.

When the spinalis and semispinalis muscles have been stripped, the multifidus and rotator muscles are dissected free.

Particularly in adult patients, sharp dissection of the tendons with a scalpel may be necessary in some cases ( Figs. 6.12 and 6.13 ).

If vertebral fusion is planned, the joint capsules of the segments involved, as well as all remnants of the tendon insertions between the spinous processes, and the interspinal ligaments need to be removed. This is done by dissecting the capsules of the vertebral joints from craniomedial to caudolateral, using a Cobb elevator ( Fig. 6.14 ).

For anatomical orientation, the 12th thoracic and the first lumbar vertebra can be used. The 12th thoracic vertebra has a regressive transverse process that overlies a readily mobile 12th rib. The first lumbar vertebra has a nonmobile costal process. The joint between the 11th and the 12th thoracic vertebrae is positioned frontally, similar to the other thoracic facet joints, whereas the T12–L1 joint is situated sagittally, similar to the lumbar facet joints. These locational characteristics apply in approximately 90 % of the cases. In the presence of anatomical uncertainties (such as lumbar ribs), a lateral radiograph may be obtained intraoperatively to determine the location.