Kyphoplasty

Introduction

Kyphoplasty is a minimally invasive surgical procedure designed to treat vertebral compression fractures. It involves restoring vertebral height and stabilizing the fracture to relieve pain and improve spinal function. This procedure is commonly used in patients with osteoporotic fractures, traumatic injuries, or pathological fractures caused by tumors.

Indications

Kyphoplasty is indicated in patients who have vertebral compression fractures that cause significant pain, functional limitation, or risk of progressive spinal deformity. Proper patient selection is essential to achieve optimal outcomes.

• Osteoporotic vertebral compression fractures: commonly seen in elderly patients with decreased bone density.
• Traumatic vertebral fractures: fractures resulting from accidents or falls that compromise vertebral integrity.
• Pathologic fractures due to tumors or metastatic lesions: vertebral fractures caused by primary or secondary malignancies.
• Failure of conservative management: persistent pain or functional limitation despite rest, analgesics, or bracing.

Anatomy Relevant to Kyphoplasty

Vertebral Structure

Understanding the vertebral anatomy is crucial for safe and effective kyphoplasty. The vertebral body supports the spinal column, and the endplates distribute load to adjacent intervertebral discs.

• Vertebral body anatomy: cylindrical anterior portion of the vertebra that bears most of the spinal load.
• Endplates and intervertebral discs: cartilaginous surfaces that separate vertebrae and allow movement while absorbing shock.
• Posterior elements and spinal canal: include the pedicles, laminae, and spinous processes which protect the spinal cord.

Surrounding Structures

Knowledge of adjacent anatomical structures is essential to prevent complications during kyphoplasty.

• Spinal cord and nerve roots: located posteriorly within the spinal canal and must be protected from injury.
• Major blood vessels: the aorta and vena cava lie anterior to the vertebral bodies and are at risk if the needle trajectory is incorrect.
• Paravertebral muscles and ligaments: muscles and ligaments support vertebral stability and must be navigated carefully during access.

Procedure

Preoperative Preparation

Successful kyphoplasty begins with thorough preoperative planning, including patient evaluation and imaging studies.

• Patient evaluation and imaging: includes X-rays, CT, or MRI to assess fracture morphology and vertebral height loss.
• Anesthesia considerations: typically performed under local anesthesia with sedation or general anesthesia depending on patient condition.
• Positioning and sterile field setup: patient is usually placed in a prone position with proper padding to maintain spinal alignment and ensure sterility.

Operative Technique

The kyphoplasty procedure involves balloon insertion to restore vertebral height, followed by cement injection to stabilize the fracture.

• Balloon insertion and vertebral height restoration: a balloon tamp is inserted into the fractured vertebra and inflated to create a cavity and restore height.
• Cement injection (polymethylmethacrylate): the cavity is filled with bone cement to stabilize the vertebra and maintain the restored height.
• Imaging guidance (fluoroscopy, CT): continuous imaging ensures accurate placement of the balloon and cement, minimizing risks.

Postoperative Care

After kyphoplasty, proper postoperative management is essential to ensure recovery and prevent complications.

• Monitoring for complications: patients are observed for neurological changes, cement leakage, or signs of infection.
• Pain management: analgesics are administered as needed to control postoperative discomfort.
• Mobilization and rehabilitation: patients are encouraged to gradually resume activity, often with guidance from physical therapy to strengthen paraspinal muscles.

Mechanism of Action

Kyphoplasty works by mechanically restoring vertebral height and stabilizing fractures while alleviating pain and preventing further deformity.

• Vertebral height restoration: balloon inflation elevates the collapsed endplates, correcting spinal alignment and kyphotic deformity.
• Stabilization of fracture: injected bone cement hardens, providing internal support to the fractured vertebra.
• Pain relief mechanism: stabilization reduces micromovements at the fracture site, decreasing nociceptive stimulation and pain perception.

Outcomes and Efficacy

Pain Reduction

Kyphoplasty has been shown to provide rapid and significant relief from pain caused by vertebral compression fractures. Patients often report improvement within hours to days after the procedure.

Improvement in Mobility and Function

Restoring vertebral height and stability allows patients to regain mobility and perform daily activities more comfortably. Physical function scores generally improve following successful kyphoplasty.

Radiographic Outcomes and Vertebral Alignment

Imaging studies post-procedure typically demonstrate restored vertebral height and correction of kyphotic deformity. This contributes to better spinal biomechanics and reduced risk of future fractures.

Complications and Risks

Cement Leakage and Embolism

Cement leakage is the most common procedural complication. Although often asymptomatic, extravasation can occasionally lead to nerve compression or pulmonary embolism.

Infection Risk

As with any invasive procedure, there is a risk of infection at the surgical site. Strict sterile technique and prophylactic antibiotics help minimize this risk.

Neurological Injury

Improper needle placement or cement extravasation can result in spinal cord or nerve root injury. Careful imaging guidance is essential to prevent neurological complications.

Adjacent Vertebral Fractures

Restoration of one vertebral level can alter load distribution along the spine, occasionally increasing the risk of fractures in adjacent vertebrae, particularly in osteoporotic patients.

Comparison with Vertebroplasty

Clinical Considerations

• Patient selection criteria: ideal candidates have symptomatic vertebral compression fractures that are refractory to conservative management.
• Contraindications: active infection, uncorrectable coagulopathy, severe spinal canal compromise, or allergy to bone cement.
• Follow-up and long-term monitoring: periodic imaging and clinical evaluation to assess vertebral stability, detect adjacent fractures, and monitor functional recovery.

References

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