Costotransversectomy Approach to the Thoracic Spine

What it exposes. The costotransversectomy gives direct posterolateral, extrapleural access to the lateral vertebral body, the disc space and the rib head / costovertebral junction, without entering the pleural cavity. It is the classic route for thoracic disc herniation, vertebral body biopsy, debridement of infection or tumour, drainage of paraspinal abscess, and limited anterolateral cord decompression. Primary indications.

• Thoracic disc herniation (soft or calcified) causing myelopathy or radiculopathy.
• Vertebral body biopsy for suspected tumour or infection.
• Debridement of pyogenic spondylodiscitis or tuberculous spondylitis with a paravertebral abscess.
• Limited anterolateral decompression for anterior cord compression (metastasis, burst fracture).
• Drainage of paraspinal or epidural abscess when a posterior approach is insufficient.
• Excision of rib head or costovertebral joint pathology. Why this approach. It provides direct posterolateral extrapleural access to the lateral vertebral body and disc while avoiding the morbidity of a thoracotomy, and gives far better access to the anterior column than a pure posterior approach. It is ideal when the pathology is lateral or anterolateral and the surgeon wishes to spare the lung, the great vessels and the sympathetic chain that are encountered in a transthoracic route. Contraindications.
• Pathology requiring extensive anterior column reconstruction (consider transthoracic or combined).
• Severe pulmonary disease precluding even brief single-lung ventilation if a pleural breach occurs.
• Previous ipsilateral thoracotomy or pleurodesis likely to obliterate the extrapleural plane.
• Midline anterior pathology best addressed by sternotomy or a transthoracic route.
• Inability to tolerate prone or lateral positioning (rare).

Position. Prone on a radiolucent table (Jackson or Wilson frame with chest rolls), or lateral decubitus (affected side up) when conversion to thoracotomy may be needed. Head neutral on a padded headrest or Mayfield pins; arms abducted less than 90 degrees; slight reverse Trendelenburg to reduce venous bleeding; knees flexed to relax the hamstrings. Confirm the level with preoperative imaging and skin marking; have a C-arm or O-arm available and tested for anteroposterior and lateral views; use neuromonitoring (MEP/SSEP) when available for myelopathic patients.

Surface landmarks.

• Spinous processes palpable in the midline; the T7 spinous process lies at the level of the inferior angle of the scapula (superior angle marks T3).
• Paraspinal gutter - the depression lateral to the spinous processes where the erector spinae bulge lies.
• Ribs - count from the twelfth rib upwards (more reliable than from the first rib).
• Incision - a paramedian or gently curved J-shaped incision, 8-12 cm long and 4-5 cm lateral to the midline, centred over the rib that articulates with the superior half of the target disc space (the rib two levels above the target vertebra). Confirm the correct rib with fluoroscopy before the skin incision.

Work down through the paraspinal layers, resect the transverse process and the proximal rib, then develop the extrapleural plane lateral to the pedicle to reach the vertebral body and disc - all while the spinal cord stays safely medial and untouched.

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Anatomy that governs the dissection. Each rib articulates with the vertebral body at the costovertebral and costotransverse joints (except the first, eleventh and twelfth ribs). The transverse process projects posterolaterally and the rib head lies immediately anterior to it, articulating with the body and disc - so resecting the transverse process and proximal rib removes the bony obstacles to the lateral vertebral body. The approach passes through the trapezius (upper thoracic) or latissimus dorsi (lower thoracic), then the erector spinae (longissimus and iliocostalis), developing the plane between the erector spinae and the rib cage. The intercostal neurovascular bundle runs in the subcostal groove on the inferior border of each rib (vein-artery-nerve from superior to inferior) and must be identified before rib resection; segmental radicular arteries feed the anterior spinal artery, and the artery of Adamkiewicz (great radicular artery) usually enters on the left between T9 and T12. The parietal pleura lines the inner rib cage and is loosely attached to the vertebral bodies - its reflection is more posterior at the costovertebral junction, which is what makes extrapleural access possible. Internervous plane. There is no true internervous plane. The dissection is intermuscular between the erector spinae (dorsal rami) medially and the intercostal muscles and external oblique (ventral rami via intercostal nerves) laterally, developed by subperiosteal elevation of the paraspinal muscles off the ribs and transverse processes. No motor nerves are divided in the superficial dissection. Safety comes from staying extrapleural and strictly lateral to the pedicle - the exiting nerve root is the only neural structure that may be sacrificed.

Structures at risk, by layer

Consequence of injury.

• Spinal cord injury - permanent paraplegia, and bowel, bladder and sexual dysfunction.
• Intercostal artery ligation at multiple levels - anterior spinal artery syndrome.
• Pleural injury - pneumothorax, haemothorax, pleural effusion, empyema.
• Nerve root sacrifice - unilateral thoracic radiculopathy (usually tolerable).
• Sympathetic injury - Horner syndrome (ptosis, miosis, anhidrosis) if above T1.

Extensile options.

• Proximal extension along the paraspinal gutter, resecting additional ribs and transverse processes for multilevel pathology; the scapula may need mobilising for upper thoracic levels (T1-T4).
• Distal extension for lower thoracic or thoracolumbar disease - the approach can reach the L1-L2 disc if the twelfth rib is resected, though the lumbar plexus and psoas become relevant below T12.
• Bilateral staged approach - a contralateral costotransversectomy at a second stage achieves circumferential decompression for tumours or severe deformity while avoiding single-stage bilateral morbidity.
• Combined with posterior stabilisation - pedicle screw instrumentation through a separate midline or extended paramedian incision, before or after decompression.
• Conversion to thoracotomy - if the extrapleural plane is obliterated or more anterior access is needed, enter the pleural cavity (requires a chest drain and respiratory support). Closure.
• Inspect the pleura; repair small tears with 3-0 absorbable suture, or insert a 28 Fr chest drain through a separate stab for large tears or a persistent air leak.
• Achieve meticulous haemostasis (intercostal vessels are the commonest source of bleeding); use bipolar cautery on the muscle edges and irrigate copiously.
• Layered closure: approximate the erector spinae to the rib remnants with absorbable suture, close the trapezius or latissimus in a separate layer, then the subcutaneous tissue and skin (staples or interrupted nylon).
• Obtain a post-operative chest radiograph to exclude pneumothorax; confirm the level and extent of decompression on anteroposterior and lateral films (CT if concern about residual compression or hardware). Post-operative care.
• Neurovascular assessment documenting lower-limb motor and sensory function; chest radiograph to exclude pneumothorax or haemothorax.
• Multimodal analgesia (avoid excessive opioids that depress respiration); incentive spirometry and chest physiotherapy to prevent atelectasis.
• Chest drain (if used) remains until output is less than 100 mL per 24 hours with no air leak; early mobilisation as tolerated.
• DVT prophylaxis with LMWH or mechanical devices; no weight-bearing restrictions unless stabilisation was performed; log-roll if posterior instrumentation placed; gradual return to activity over 4-6 weeks.
• Follow-up at 2 weeks (wound check, suture or staple removal), 6 weeks (clinical review, radiographs if instrumented), 3 months (CT or MRI if indicated) and 6-12 months (final review).

• Spine tumour decompression and stabilisation - decompression, biopsy and combined posterior stabilisation for metastatic disease.
• Excision of thoracic disc herniation (soft or calcified) causing myelopathy or radiculopathy.
• Vertebral body biopsy for suspected tumour or infection.
• Debridement of pyogenic spondylodiscitis or tuberculous spondylitis with a paravertebral abscess.
• Drainage of paraspinal or epidural abscess when a posterior approach is insufficient.
• Limited anterolateral decompression for anterior cord compression (metastasis, burst fracture).
• Excision of rib head or costovertebral joint pathology.

Guidelines, registries and global practice. Costotransversectomy is used worldwide for thoracic disc herniation, spinal tumour and infection when posterolateral extrapleural access is needed, and is a standard component of neurosurgical and orthopaedic spine fellowship training. AO Spine and the North American Spine Society emphasise that myelopathic thoracic disc herniations should be approached from the side of the pathology using an extrapleural route when possible, avoiding cord manipulation; NICE (UK) and the Spine Society of Australia recommend costotransversectomy or lateral extracavitary approaches for lateral and anterolateral thoracic disc disease, reserving transthoracic routes for midline calcified discs needing extensive anterior reconstruction. Thoracic disc herniation requiring surgery is rare (approximately 1 per 1,000,000 per year); surgical series consistently report neurological improvement in 80-95 percent of myelopathic patients when the cord is decompressed without manipulation, with pleural injury rates of 5-15 percent across large series, the majority managed with chest drainage. In high-resource centres intraoperative neuromonitoring (MEP/SSEP) is routine for myelopathic patients; in resource-limited settings the same anatomical principles apply and the approach is performed safely with meticulous technique. Chest-drain availability and post-operative chest radiography remain essential everywhere. Consent. Discuss pleural injury requiring a chest drain (5-15 percent), neurological deterioration (1-3 percent), wrong-level surgery (a never event), wound infection (2-5 percent), chronic radicular pain (10-20 percent), and the possibility of staged posterior stabilisation if anterior column reconstruction is required.