Courtesy: Jacob Oh, Chief of Spine Surgery, Tan Tock Seng Hospital, Singapore

 

Introduction

Osteoporotic vertebral compression fractures are becoming increasingly common due to the growing prevalence of osteoporosis. While many fractures can be managed conservatively or with posterior fixation alone, certain fracture patterns require anterior column reconstruction to achieve adequate stability, decompression, and long term outcomes.

This lecture discusses minimally invasive anterior corpectomy techniques for thoracolumbar fractures and demonstrates how these approaches can provide the advantages of anterior reconstruction while minimizing the morbidity traditionally associated with open anterior surgery.

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Why Posterior Surgery Remains the Workhorse

For most thoracolumbar fractures, a posterior approach remains the preferred option because it is:

• Familiar and reproducible
• Technically straightforward
• Relatively fast
• Effective for decompression
• Suitable for emergency situations

Pedicle screw fixation remains the foundation of treatment for many spinal fractures.

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When Anterior Column Support Becomes Necessary

Certain fractures cannot be adequately managed through a posterior approach alone.

Typical indications include:

• Vertebral body height loss greater than 50%
• Kyphotic angulation greater than 30°
• Severe anterior column destruction
• Large retropulsed fragments causing major canal compromise
• Osteoporotic Fracture (OF) Type 4 and Type 5 injuries
• Pathological vertebral body collapse

In these situations, anterior reconstruction provides:

• Superior anterior column support
• Improved fusion rates
• Direct neural decompression
• Ability to shorten posterior constructs

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Anterior Approaches to the Spine

L5 Vertebral Body

Direct anterior approach

Similar to an anterior lumbar interbody fusion approach.

Key considerations:

• Mobilization of the iliac vessels and inferior vena cava
• Lateral access is limited by the iliac crest

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L1 to L5 Vertebral Bodies

Lateral retroperitoneal approach

Commonly associated with XLIF and OLIF techniques.

Approach involves:

• Splitting abdominal wall musculature
• Entering the retroperitoneal space
• Accessing the vertebral body through an oblique corridor anterior to the psoas muscle

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T11 and T12 Vertebral Bodies

Retropleural approach

The diaphragm becomes an important anatomical landmark.

• Structures below the diaphragm are approached retroperitoneally
• Structures above the diaphragm require retropleural or transthoracic access

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Mid Thoracic Spine

Typically approached through:

• Right retropleural approach
• Right transthoracic approach

A right sided approach avoids the descending thoracic aorta.

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Challenges of Traditional Anterior Surgery

Historically, anterior surgery has been associated with substantial morbidity.

Potential disadvantages

• Significant blood loss
• Difficult dural repair
• Major vascular injury risk
• Exposure related complications
• Limited multilevel access
• Need for assistance from vascular or thoracic surgeons

These concerns motivated the development of minimally invasive techniques.

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Case 1: L4 Pathological Fracture from Metastatic Disease

Clinical Presentation

• 65 year old woman
• Breast cancer metastasis
• Severe back pain
• Neurogenic claudication
• Foot drop
• L4 pathological fracture with severe cauda equina compression

Surgical Strategy

1. Retroperitoneal approach
2. L4 corpectomy
3. Direct decompression
4. Cage reconstruction
5. Posterior fixation

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Step 1: Retroperitoneal Approach

Key steps

• Patient positioned laterally
• Approximately 5 cm oblique incision
• External oblique fascia split
• Transversalis fascia opened
• Retroperitoneal fat identified
• Psoas muscle exposed
• Fat swept anteriorly
• Oblique corridor developed

Muscles are split rather than detached, minimizing tissue damage.

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Step 2: Discectomy

The discectomies are performed before the corpectomy.

Advantages:

• Better visualization
• Improved preparation of fusion surfaces
• Reduced bleeding during reconstruction

Both adjacent disc spaces are thoroughly prepared.

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Step 3: Corpectomy

Dr. Oh prefers an osteotome rather than a burr because:

• Less bleeding
• Preservation of bone graft material
• Greater efficiency

Important technical principle:

• Instruments remain perpendicular to the vertebral body
• Avoid excessive anterior or posterior deviation

This reduces the risk of vascular or neural injury.

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Step 4: Direct Decompression

After corpectomy:

• Pedicle identified
• Canal entered
• Retropulsed fragments removed
• Exiting nerve root visualized
• Thecal sac decompressed

A major advantage of the anterior approach is the ability to directly remove retropulsed fragments from the spinal canal.

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Step 5: Reconstruction

Key steps

• Fracture reduction achieved by table adjustment
• Vertebral defect measured
• Expandable cage inserted
• Cage expanded to restore vertebral height and alignment

Final fixation was completed with percutaneous posterior instrumentation.

Results

• Blood loss approximately 250 mL
• Excellent fusion at one year
• Stable alignment
• No implant loosening

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Case 2: L4 Burst Fracture Treated with Robotics

Unique Feature

Single position surgery using robotic guidance.

Advantages Observed

• Accurate screw placement
• Ability to plan screw trajectories preoperatively
• Short segment fixation possible due to strong anterior reconstruction

Construct:

• One level above
• One level below
• Cement augmented fixation

Clinical Outcome

• Sitting on postoperative day 1
• Ambulating on postoperative day 2
• Independent stair climbing by day 4

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Role of Robotics

Main advantages

• Detailed preoperative planning
• Larger and longer screw trajectories
• Ability to place difficult screws
• Facilitation of single position surgery

Limitations

• Cost
• Continued need for fluoroscopy
• Preoperative CT scan required
• Radiation exposure not completely eliminated

According to Dr. Oh, the greatest benefit currently lies in planning rather than radiation reduction.

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Case 3: T12 Burst Fracture

Clinical Features

• 88 year old woman
• Severe T12 collapse
• Cord compression
• Cord signal changes
• Progressive functional limitation

Surgical Goals

• Correct kyphosis
• Decompress neural elements
• Restore anterior support
• Achieve stable fixation

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Retropleural Approach

Key steps

• T10 rib resected
• Pleura identified
• Retropleural plane developed
• Access obtained to T12 vertebral body

Advantages:

• Avoids entering the thoracic cavity
• Reduces pulmonary complications

The remaining steps are similar:

• Discectomy
• Corpectomy
• Decompression
• Cage reconstruction
• Posterior fixation

Outcome

• Standing on postoperative day 1
• Excellent canal decompression
• Successful fusion

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Bone Grafting Strategy

Preferred option

Local autograft obtained during corpectomy.

Tumor cases

Use:

• Demineralized bone matrix (DBM)

Dr. Oh notes that fusion often occurs through:

• The cage
• Contralateral untouched structures
• Natural healing potential of surrounding tissues

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Bone Morphogenetic Protein (BMP)

Current Perspective

BMP remains available and is still used.

Potential concerns include:

• Excessive bone formation
• Radiculitis
• Seroma formation, particularly in the cervical spine

Modern practice emphasizes:

• Lower doses
• Careful patient selection

BMP may be especially useful in minimally invasive surgery where local bone graft volume is limited.

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Neurological Deficits in Osteoporotic Fractures

According to Dr. Oh:

• Neurological deficits occur in fewer than 10% of osteoporotic compression fractures.
• Many fractures demonstrate canal compromise without neurological symptoms.
• Canal remodeling frequently occurs during healing.

Surgical decisions depend on:

• Severity of neurological impairment
• Degree of pain
• Progressive collapse
• Development of kyphosis

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Timing of Surgery

For most osteoporotic compression fractures:

1. Initial conservative treatment.
2. Follow up after approximately two weeks.
3. Repeat standing radiographs.

Surgery is considered if:

• Symptoms persist
• Vertebral collapse progresses
• Kyphosis worsens
• Neurological deficits develop

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Role of Vertebroplasty and Kyphoplasty

Dr. Oh continues to use cement augmentation procedures selectively.

Appropriate candidates

• Severe pain
• Failure to mobilize
• Persistent symptoms despite conservative treatment

Typical practice

• Avoid intervention during the first week
• Observe initial recovery
• Consider augmentation after several weeks if pain remains disabling

Important caution

Burst fractures carry a risk of cement leakage into the spinal canal and require careful patient selection.

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Key Take Home Messages

1. Posterior fixation remains the standard treatment for most thoracolumbar fractures.
2. Anterior column support should be considered in severe vertebral collapse, marked kyphosis, large retropulsed fragments, and unstable osteoporotic fractures.
3. Minimally invasive anterior corpectomy allows direct decompression with substantially less morbidity than traditional open anterior surgery.
4. Expandable cages provide excellent anterior support and may permit shorter posterior constructs.
5. Robotic assistance improves surgical planning and accuracy but does not completely eliminate radiation exposure.
6. Elderly patients can achieve rapid mobilization and excellent functional recovery following minimally invasive anterior reconstruction.