Vertebral Augmentation

Article Author:
Alexander Dydyk
Article Editor:
Joe M Das
Updated:
4/14/2020 11:48:51 AM
PubMed Link:
Vertebral Augmentation

Introduction

Kyphoplasty and vertebroplasty are the most common forms of vertebral augmentation. They can be defined as the injection of bone cement, often under fluoroscopy, into a fractured vertebra percutaneously.[1][2] The primary purpose of these procedures is the improvement of acute pain and patient function. Furthermore, they can prevent the recurrence of vertebral pain in the long-term as well.

Vertebroplasty has been the focus of the majority of systematic reviews for vertebral augmentation rather than kyphoplasty. The results of meta-analyses regarding the efficacy of vertebral augmentation procedures to reduce pain have been largely inconclusive. The mixed results and inconclusive evidence can often be contributed to study design or the quality of the studies performed. Interestingly, when compared to conservative management, vertebral augmentation has been shown to be favorable with improved pain as well as disability in patients. When compared to a placebo-controlled trial or sham vertebral augmentation, the results do not show a clinically significant benefit for vertebral augmentation in osteoporotic compression fractures of the spine.[3][2][4][5][6]

Complicating the evidence is how multiple studies have shown a mortality benefit for patients undergoing vertebral augmentation for refractory pain secondary to osteoporotic compression fractures of the spine when compared to conservative management.[7][8] Separate, similar studies have not found a significant difference in mortality between patients undergoing vertebroplasty compared to those undergoing conservative management when accounting for selection bias. The studies which showed no benefit to vertebral augmentation did not continue observing patients for longer than one year.[9]

There have been multiple conflicting controlled trials regarding patients with osteoporotic compression fractures of the spine opting for vertebroplasty. Three separate controlled trials showed no significant reduction in pain for vertebral augmentation when compared to controls. There was also shown to be no decreases in the use of oral pain medications or improvement in reported quality of life and the reported disability. In comparison, one sham-controlled trial did show a significant decrease in reported pain for patients undergoing vertebral augmentation. Additionally, this study showed improvement in reported pain scores as well as a decrease in disability scores. Researchers reported these scores at one, three, and six months duration following treatment.[10][11][12][13][14]

There have been concerns for discrepancies in study designs across various studies. Some of these concerns include the duration of back pain before vertebroplasty, and lack of confirmation of bone marrow edema in the location of an osteoporotic compression fracture prior to augmentation. Also, vertebral augmentation not being completed during the acute or subacute phases following a compression fracture. Acute would be considered pain for less than one month in duration, and subacute considered pain for less than three months in duration. Symptoms for less than three-month duration are considered to be the most beneficial time for the patient to undergo augmentation.[10][11][12][13][14]

Potential alternatives for patients who have contraindications for vertebral augmentation are median branch radiofrequency ablation or facet joint injections for attempted pain relief.[15] Bracing would also be a potential option for the acute or subacute phase of pain after an osteoporotic compression fracture, to aid in pain control. However, bracing can lead to atrophy of the core musculature with prolonged use. Bracing has also been shown to have limited efficacy with long term use.[16][17]

Spinal fusion surgery can loosely be described as fusing two or more of a patient's vertebral bodies together. Studies have shown patients undergoing surgery have decreased levels of pain in both short and intermediate follow-up after surgery. However, there are limited disability outcomes for patients undergoing vertebral fusion. There has been a recommendation for patients with low back pain greater than one year in duration, with pain non-radicular in nature, to undergo spinal fusion. Some experts consider spinal fusion to be a reasonable treatment option for refractory osteoporotic compression fracture, despite having inadequate evidence of its effectiveness in the long term.[18][19][20][21][22]

Anatomy and Physiology

Thirty-three vertebrae comprise the human spine. Each vertebra is organized one on top of the other. The lumbar spine, made up of five vertebrae, is the most common site of compression fractures that require vertebral augmentation. 

Between each vertebra is the intervertebral disc, which acts as shock absorbers and keeps bones from contacting each other.

The posterior aspect of the vertebra contains a spinous process that is palpable on physical exam. Lateral to the spinous process are two transverse processes, which connect to the spinous process via laminae.

Pedicles connect the vertebral body to the transverse processes anteriorly. Together the pedicles, laminae, spinous, and transverse processes make up the vertebral arch. The spinal canal runs within the hollow space created by the vertebral body anteriorly, transverse processes laterally, and laminae and spinous process posteriorly. The spinal cord resides within this spinal canal, as well as blood vessels, fat, and ligaments. 

The spine cord runs from the brainstem to the first lumbar vertebra (L1). It is roughly 2.5 cm thick. Inferior to the L1, the spinal cord nerves separate into the cauda equina.

There are 31 spinal nerves that branch off of the spinal canal. The spinal nerve exit the spinal canal under the pedicles at the intervertebral foramen. These spinal nerves are organized and numbered according to the vertebra which exists in the spinal canal, above its respective spinal nerve. There are eight cervical spinal nerves numbered C1 through C8, 12 thoracic spinal nerves, numbered T1 through T12, five lumbar spinal nerves are L1 through L5, and five sacral spinal nerves numbered S1 through S5. There is also one coccygeal nerve. 

Each vertebra has four facet joints; two superior facets and two inferior facets connect each vertebra. For example, the superior facets of L2 connect the inferior facets of L1 superiorly, and the inferior facets of L2 connect the superior facets of L3 inferiorly. 

Paravertebral muscles run longitudinally along the spine. 

There are three main ligaments of the spine; the ligamentum flavum, anterior longitudinal ligament (ALL), and the posterior longitudinal ligament (PLL). The PLL and ALL are continuous band-like structures that run along the spinal column of the vertebral bodies. The ALL and PLL prevent excessive motion of the vertebrae. Separately, the ligamentum flavum attaches between the lamina of each vertebra.

Indications

The basis of proceeding with vertebral augmentation despite having limited evidence when compared to placebo in patients with osteoporotic compression fractures is the lack of generalized conclusions for various trials and expert opinion. Despite multiple studies, there is insufficient information to conclusively determine if there are specific patient subpopulations that would or would not benefit from vertebral augmentation.

If a patient's pain secondary to an osteoporotic compression fracture is unable to be weaned off from opioid analgesics because of persistent nature or if a patient has developed significant side effects to opiate analgesics, some expert opinion suggests vertebral augmentation as a possible treatment option for osteoporotic compression fractures. Significant side effects from opioid analgesia would include constipation, respiratory depression, confusion, nausea, or urinary retention. 

One study compared patient demographics for those with persistent and severe back pain considering undergoing vertebral augmentation. There were two groups in the study. Groups either underwent kyphoplasty or opted for conservative management. Patients included in the study had pain for greater than three weeks duration. Patients who responded to conservative management did not undergo vertebral augmentation. The augmentation group included patients who failed conservative management. Kyphoplasty served as an alternative therapy. The conservative management population had better pain scores at a one-year follow-up when compared to the vertebral augmentation group. The augmentation group was found to be more obese, with more severe osteoporosis, and with a T-score of less than -2.8. The augmentation group was found to be older and with greater compression of the vertebral body when compared to the conservative treatment group. Patients who opted for kyphoplasty had significantly greater risk factor compared to patients who responded to conservative therapy.[23]

Multiple studies have been done focusing on patients suffering from multiple myeloma with metastatic pathological compression fractures. In this select group of patients, kyphoplasty has been found to significantly decrease the need for patients' requirement of walking aids post vertebral augmentation as well as the need for oral pain medication. In one study done in patients with pathological compression fractures, kyphoplasty led to a decrease in the necessity for bedrest secondary to pain, compared to conservative management.

In a separate uncontrolled study, kyphoplasty was shown to significantly decrease patients' reported pain and an improvement in their underlying physical and social functioning, as well as patient-reported vitality. Over 80% of the patients who underwent kyphoplasty reported pain relief in this study.[24][25]

An additional study of 57 patients with a pathological fracture secondary to malignancy, there was either a complete or significant resolution of pain in 84% of patients who underwent kyphoplasty or vertebroplasty. The pain scores remained significantly decreased at one year following the procedure.[26]

Over half of the systematic reviews focused on vertebral augmentation for patients with underlying cancer; there was a significant improvement in pain scores following the procedure. The research showed similar scores for the reported need for pharmacological analgesia and inpatient disability.[27][28][29]

Another indication for vertebral augmentation would include a vertebral angioma with no neurological symptoms and intractable pain.

Contraindications

The selection criteria for patients undergoing vertebral augmentation would not include patients in mild or moderate pain secondary to a vertebral fracture. Conservative and pharmacological management should be the first-line treatment. 

Patients with an osteoporotic compression fracture should initially receive medical management. The evidence has not shown vertebral augmentation to be more beneficial than a placebo in this population. Thus vertebral augmentation is not indicated in mild or moderate pain for osteoporotic compression fractures.[2]

The American Society of Bone and Mineral Research advised against the use of kyphoplasty or vertebroplasty in acute osteoporotic compression fractures.[16]

When a vertebral fracture is severe, or a patient’s facet joint has suffered compromise, it may contraindicate vertebral augmentation.

A relative contraindication to vertebral augmentation is a vertebral body fracture with a posterior cortical breach.[30] The concern for kyphoplasty in patients with posterior cortical branches arises when balloon inflation stops with pressures that are above 250 psi. The balloon then contacts the cortical surface of the vertebral body. Posteriorly, this could lead to extravasation of the cement and neurological damage.[31]

A complete vertebral body collapse would be a true contraindication to vertebral augmentation. An underlying fracture of the posterior wall of the vertebra has potentially serious complications; this would include extravasation of cement, leading to catastrophic neurological damage.[32]

Other absolute contraindications include unstable fractures, active infection of the spine or the injection site, and coagulation disorders. 

Equipment

  • Local anesthetic 
  • Fluoroscope 
  • Trochar (large hollow tube) 
  • For kyphoplasty, a balloon tamp and catheter are needed to inflate the vertebral body
  • Peripheral intravenous cannula with intravenous fluids
  • The vital sign monitoring device 
  • Orthopedic bone cement
  • Bone cement delivery device

Personnel

  • The physician performing the procedure: often specializes in interventional radiology, interventional pain, or neurosurgery
  • Nurse technologist 
  • The operator of the fluoroscope: X-ray technician or medical assistant 

Preparation

These procedures often take place in an outpatient setting; they can be performed with or without sedation or general anesthesia.[1][2]

The clinician usually orders labs before the procedure

The kidney function is frequently evaluated and is necessary when using contrast. Patients with reduced kidney function are at increased risk for contrast-induced nephropathy. 

  • Basic metabolic panel with estimated glomerular filtration rate (BMP with eGFR)

Coagulation factors are also often ordered before the procedure to evaluate for blood clotting. 

  • Prothrombin time/international normalized ratio (PT/INR), complete blood count (CBC) 

The clinician would also have ordered and reviewed X-rays and/or magnetic resonance imaging (MRI) of the spine before the procedure.

Technique

The difference between kyphoplasty and vertebroplasty is as follows; in kyphoplasty, there is an inflatable balloon inserted into the fracture of the vertebral body. This balloon creates a low-pressure space for the injection of bone cement. This process is to help reduce underlying vertebral fractures. In comparison, vertebroplasty is the injection of the bony cement without inflatable balloon placement, directing into the vertebral body.[1][2]

When compared, vertebroplasty and kyphoplasty have different criteria for patients to undergo augmentation. Vertebroplasty is indicated if an MRI shows bone marrow edema in a case of suspected back pain secondary to an osteoporotic compression fracture. Bone marrow edema is typically consistent with an underlying fracture of the vertebra. Furthermore, in vertebroplasty, there only needs to be minimal underlying compression of the vertebral body to undergo the procedure. 

Kyphoplasty is a technique that requires a bilateral percutaneous balloon tamp inserted into the vertebral body. Given kyphoplasty is a more technically challenging procedure, it is also more expensive when compared to vertebroplasty. Kyphoplasty is also performed much more frequently than vertebroplasty. When comparing outcomes of kyphoplasty to vertebroplasty, there are limited results. Evidence for both long and short-term pain and disability scores is largely inconclusive in comparison studies.[33][2][34][35][36][37]

When comparing kyphoplasty to vertebroplasty, multiple observational studies of patients with osteoporotic vertebral compression fractures have shown kyphoplasty improving patients' pain as well as decreasing disability.[1][38][39][40][41] The results have been less conclusive for vertebroplasty. Although encouraging, there have been no sham-control trials done for kyphoplasty. There are only limited randomized control trials on kyphoplasty. The largest randomized control trial compared kyphoplasty to nonsurgical care, including pharmaceutical management. The results of this trial showed a statistically significant improvement for both pain and quality of life scores after one month of therapy. This improvement failed to be significant after 12 and 24 months of observation.[42][43][36] The pain scores were measured at 12 months following treatment but not three or six months following the intervention. A study flaw was the failure to capture pain and quality of life scores during bone healing of an osteoporotic compression fracture in the acute and subacute period following the fracture.

Complications

The predominant side effect or reaction associated with both kyphoplasty and vertebroplasty is extravasation of the injected cement, which potentially leads to increased pain and or damage to the underlying nerve root. 

Reports have demonstrated that cement embolization to pulmonary vasculature can occur following procedures. However, research has yet to document any adverse reactions regardless of radiological evidence of embolization.[44]

Recent studies have shown vertebral cement to be associated with bone necrosis.[45][46][47]

Infection is an infrequent complication from both kyphoplasty and vertebroplasty. If it occurs, it can be serious.

There has also been an association of new fractures in many randomized control trials after patients received vertebroplasty when compared to controls.[48][49][50][51][52][53]

Clinical Significance

There is evidence to show vertebral augmentation can decrease height loss and the severity of the spinal deformity.[54]

The American Society of Radiation Oncology recommends patients with a pathological fracture secondary to vertebral metastasis who elect to undergo vertebroplasty to also proceed with co-current radiation therapy.[55]

There is a limited side effect profile for the majority of patients undergoing vertebral augmentation.

There is promising evidence of pain relief in patients with metastatic multiple myeloma and similar evidence for malignancy with bony metastasis.

Vertebral augmentation should not be considered a first-line treatment option for patients with osteoporotic compression fractures of the lumbar spine. Some experts recommend it for refractory cases with persistent and severe pain. 

There have been limited studies completed on kyphoplasty in comparison to vertebroplasty. More randomized controlled trials need to be completed for kyphoplasty to determine its efficacy fully.

Enhancing Healthcare Team Outcomes

Vertebral Augmentation 

Vertebroplasty is a minor procedure and can be associated with a few complications but is often associated with limited efficacy, except for select populations. Thus it is imperative to identify the correct demography and perform a thorough assessment of the patient before vertebral augmentation. A team approach is an ideal way to limit an unnecessary procedure. Before vertebroplasty, the patient should have the following done:

  • Failed conservative management 
  • The patient has shown radiographic evidence of pain in the area of the compression fracture
  • The patient has considered alternative treatment options 
  • A diagnosis of an osteoporotic compression fracture or a pathological fracture of the lumbar spine secondary to multiple myeloma or similar malignancy has occurred
  • The patient has undergone evaluation by either neurosurgery, pain medicine, or orthopedic surgery
  • Advanced imaging such as MRI has taken
  • placeLabs to assess for renal function and coagulation disorders have been complete

The procedure requires the efforts of an interprofessional healthcare team. While care may initiate with the family physician or GP, a spinal specialist (usually an orthopedist or neurosurgeon) should be brought in and lead the treatment plan. Orthopedic and medical/surgical specialty-trained nursing staff can assist throughout all aspects of the procedure, from prep, intraoperative, and post-op care, monitoring the patient, and informing the surgeon of any concerns as well as assisting with patient and family education. Post-surgical recovery may include physical or occupational therapy, and these professionals must chart and report to the rest of the team on patient progress. The entire interprofessional healthcare team must be involved, communicating, and operating from the same information base in these vertebral augmentation procedures, to drive the best possible patient outcomes. [Level 5]

Nursing, Allied Health, and Interprofessional Team Interventions

  • Before the procedure, patients can take their home medications with water but maybe on nothing by mouth status for up to six hours before the procedure.
  • Patients are often monitored for neurological changes following procedure.
  • Patients are often monitored for up to an hour following the procedure. 
  • The patients will be scheduled for follow-up following the procedure.
  • The patient can meet with the physician provider or mid-level provider for post-operative follow-up.

Nursing, Allied Health, and Interprofessional Team Monitoring

Post-procedure follow-up, including patient monitoring for repeat fracture, infection, local pain, difficulty in breathing, and chest pain (concern for possible pulmonary embolism secondary to extravasated bone cement) is necessary.


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