Introduction

There is no shortage of health consequences of aging. Osteoporosis, low bone mineral density, and associated vertebral fractures have been a leading cause of diminished quality of life for many people. It was found that the lifetime risk of clinical vertebral fractures at age 50 years is about 15.6% for women and 5% for men. However, only about 33% of people with vertebral fractures develop debilitating symptoms limiting their daily activities. Vertebral augmentation procedures are becoming common for treating osteoporotic vertebral fractures (OVFs) in older patients who have diminished quality of life due to debilitating back pain that limits their physical and daily living activities. ^,

Most patients improve with conservative management. However, historically, some patients with unbearable and debilitating pain had to resort to neurosurgery, such as anterior decompression and fusion or posterior instrumentation of the vertebra, which are usually poorly tolerated due to the patient’s age and are typically unsuccessful due to the poor quality of bone. ^, Consequently, minimally invasive procedures such as vertebroplasty and kyphoplasty, which comprise the vertebral augmentation umbrella, have become a treatment modality of choice. Both percutaneous vertebroplasty and kyphoplasty entail injecting polymethylmethacrylate (PMMA) bone cement into the compressed vertebral body. Kyphoplasty is a modification of vertebroplasty, which involves introducing an inflatable balloon tamp to create a cavity that allows for restoration of the vertebral body height and low-pressure cavity for subsequent cement injection. Kyphoplasty offers a lower risk of cement leakage, reduced incidence of subsequent adjacent fractures, and increases vertebral body height. However, the high cost of this procedure could be a limiting factor. A meta-analysis and systematic review by Wang et al. concluded that both methods are equally effective, yielding similar clinical outcomes. More novel approaches, such as vertebral osteotomy and use of the SpineJack system (Stryker, Kalamazoo, MI), have been developed in recent years that have proved to be promising in decreasing the risk of cement leakage and in improving outcomes. Vertebral osteotomy was found to provide better flexibility in reaching the cracks of the vertebral body where traditional vertebroplasty was unable to do so, reducing the amount of cement used and improving the instability among the adjacent vertebrae. A SpineJack system is a device for mechanical kyphoplasty that resembles a miniature jack with the ability to expand with a large force, in a progressive and controlled manner, in a craniocaudal direction. This allows treatment of fractures that are more chronic—traumatic fractures and primary or secondary bone tumors. Vertebral augmentation has also been increasingly attempted as a palliative treatment of advanced metastatic spine diseases to improve quality of life. ^, To optimize these potential benefits of vertebral augmentation, proper patient selection to undergo the procedure is critical.

Relevant anatomy and pathophysiology

A human spine consists of a total of 33 vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, and 4 fused coccygeal. Each vertebra contains a vertebral body that is typically weakened, deformed, or cracked in patients with osteoporosis. The pain from vertebral fractures is thought to be due to micromotion between the fragments at the fracture site. In some instances, the pain during an acute phase of the fracture can last up to 6 weeks. However, the physiological sequelae, including chronic pain, can remain significantly longer and lead to notable morbidity and mortality. In addition, a patient’s tendency toward limited activity or increased bed rest can lead to a vicious pain cycle and increased risk of additional fractures due to further loss of bone mineral density. Inactivity and rest further lead to loss of height and thoracic hyperkyphosis, affecting pulmonary function, causing early satiety, and contributing to mood changes.

Typical conditions that may be treated with vertebral augmentation include osteoporotic vertebral fractures, vertebral hemangiomas, and metastatic lesions.

Candidate selection

An evaluation of any new patient presenting to a chronic pain clinic begins with focused history, including timing, intensity, and character of the pain. Indication assessment for a patient to undergo a vertebral augmentation procedure should include a history of failure of prior noninterventional options and continuation of intractable pain despite changes in diet; physical therapy; occupational therapy; acupuncture; weight-bearing/impact-loading daily exercises; pharmacological modalities, including antiresorptive agents in conjunction with calcium and vitamin D supplements, and nonopioid and opioid analgesics; and, finally, cessation of smoking. Physical exam findings include tenderness to palpation along the spinous processes without radiation, which typically subsides with sitting or lying supine. Some patients will suffer from psychological manifestations of immobility and the inability to maintain basic activities of daily living, leading to social isolation.

Imaging is essential to candidate selection for vertebral augmentation as it is needed to visualize vertebral damage or degeneration. The fastest, lowest-cost, and most widely available imaging modality to detect spinal fractures remains spinal radiography. However, the best imaging modality to identify and confirm the osteoporotic fractures and differentiate them from those of neoplastic origin is magnetic resonance imaging (MRI), which is also valuable for distinguishing acute/subacute versus chronic vertebral fractures. Alternatively, a computed tomography (CT) scan with a technetium bone scan can be utilized for patients for whom MRI is contraindicated. A baseline dual-energy X-ray absorptiometry (DEXA) scan is also helpful to assess the risk of future fractures.

Indications for vertebral augmentation are as follows

• 1.
  

  Painful osteoporotic fractures that are resistant to nonoperative management and pharmacological therapy for 3 weeks

  
  
• 2.
  

  Pain secondary to bone tumors, such as aggressive hemangioma, giant cell tumor, and bone cysts

  
  
• 3.
  

  Pain secondary to extensive osteolysis from multiple myeloma, lymphoma, or metastasis

  
  
• 4.
  

  Painful fractures associated with osteonecrosis

  
  
• 5.
  

  Traumatic fractures

  
  
• 6.
  

  Vertebral body stabilization before open instrumentation surgery

Contraindications to vertebral augmentation include the following ^,

• 1.
  

  Fractures improving on medical therapy

  
  
• 2.
  

  Highly unstable spine fractures, as in a patient with ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis (DISH)

  
  
• 3.
  

  Osteomyelitis or active systemic infection

  
  
• 4.
  

  Severe uncorrectable bleeding disorder and coagulopathy

  
  
• 5.
  

  Allergy to bone cement or contrast agent

  
  
• 6.
  

  Radicular pain, cauda equina syndrome, or myelopathy

  
  
• 7.
  

  Fracture of the posterior column, increasing the risk of cement leakage

Complications

Vertebral augmentation procedures have been proven to be a promising alternative to open surgical interventions to treat osteoporotic fractures in the right population. However, as with any procedure, risks such as bleeding, infection, and damage to the surrounding tissues are not negligible. Therefore selecting the correct patients to undergo this procedure is essential to minimize complications. Some case reports exist describing complications such as radiculopathy and paraplegia as a result of cement leakage into the epidural space and neural foramina leading to cord compression, cement pulmonary embolism as a result of liquid PMMA escaping into the venous system, and lumbar arterial injury leading to hemorrhage. In addition, the prevalence of recollapse of the augmented vertebra and adjacent vertebral fracture following the vertebral augmentation has led to exploring risk factors that could be predictive of such complications. Previous studies identified that female gender, low T-score, preoperative intervertebral cleft (IVC), fracture level in the thoracolumbar region, preoperative severe kyphotic deformity, solid lump cement distribution pattern, and higher vertebral height restoration (VHR) were significantly associated with recollapse and adjacent vertebral fracture. With all potential complications in mind, it is essential to weigh the benefits and risks of undergoing a vertebral augmentation procedure. Patients should be selected for these procedures only if the benefits of the procedure outweigh the potential complications. Therefore a thorough assessment of a patient’s history, a well-performed physical exam, and proper imaging studies are needed to select patients for vertebral augmentation correctly. This is especially important in older adults for whom the risk of undergoing the procedure may outweigh the benefit.