Neurointerventions: Vertebral Compression Fractures: Evaluation and Management (2024)

Neurointerventions

Guest Editors, Venu Vadlamudi, MD, RPVI, FSIR, FSVM, FASA and Martin Radvany, MD

Abstract

Painful vertebral body compression fractures are prevalent in elderly patients. Two-thirds of patients will have spontaneous resolution of pain in 4 to 6 weeks and initial management is nonoperative with pain management and bracing. A focused history and exam can identify patients likely to benefit from vertebral body augmentation (e.g., vertebroplasty or kyphoplasty). Patients with persistent back pain and bone marrow edema on magnetic resonance imaging may benefit from injection of cement into the fractured vertebral body with either vertebroplasty or kyphoplasty. Patients most likely to benefit are those with severe pain refractory to nonoperative management who are offered intervention within 3 weeks. The procedure is usually performed as an outpatient with rare complications. Most patients report immediate, durable pain relief.

Keywords: osteoporosis, vertebral compression fracture, vertebral body augmentation, kyphoplasty, vertebroplasty, interventional radiology

Vertebral Compression Fractures

Vertebral compression fractures (VCFs) are predominantly due to osteoporosis, which afflicts 25% of women and 5.6% of men older than 65 years.¹Other etiologies of VCF include infections and neoplasms.²VCFs mostly affect the thoracolumbar spine (most common at T12–L2) due to mechanical forces related to the transition from the relatively mobile thoracic spine to the relatively fixed lumbar spine.

The natural history of VCF is resolution of pain in 4 to 6 weeks in two-thirds of patients, and therefore initial management is nonoperative.³Due to prevalence of comorbidities in elderly patients, surgery is typically offered only for those presenting with neurologic compromise.⁴Patients with persistent pain may eventually present to interventional radiology clinic or the inpatient consultation service for consideration of vertebral body augmentation, including vertebroplasty and kyphoplasty using polymethylmethacrylate (PMMA) cement.

Patient Selection

The initial patient history should include the onset of symptoms, quality and severity of pain, and exacerbating factors. In those with chronic back pain, patients frequently point to a specific day that their symptoms worsened which may indicate an acute VCF. Typical pain descriptors are midline pain localized to a specific spinal level with a band-like distribution that is worse with movement or weight bearing. Radicular symptoms are atypical and should warrant evaluation for nerve compression or spinal stenosis.⁵It is important to determine whether there are symptoms of spinal cord compression, such as bowel or bladder dysfunction, to properly triage these patients to neurosurgical evaluation.

On physical exam, the patient will have focal midline or paramidline tenderness with firm palpation. Kyphosis may result in decreased respiratory capacity.⁴Extremity numbness or weakness suggests nerve impingement of different etiologies, which may benefit from alternative therapy such as epidural steroid injection.⁵

It can be helpful to further evaluate patients with a validated survey to determine pain severity (Roland–Morris Back Pain score), quality of life (the Short Form 36 Health Survey), or disability (Oswestry Disability Index).⁴

Patients should have laboratories drawn to check for coagulopathy. The Society of Interventional Radiology (SIR) recommends platelets of at least 50,000 and international normalized ratio (INR) of at most 1.5.⁶Antiplatelets and anticoagulants should be held according to SIR guidelines for high-risk procedures.

Preprocedural Imaging

Preprocedural magnetic resonance imaging (MRI) is preferred to document bone marrow edema on short tau inversion recovery (STIR) sequence.⁴MRI permits localization of the afflicted vertebral body, defines the fracture clefts, and triages patients to nonoperative management or vertebral body augmentation. Additional benefits of MRI include finding additional acute VCF which may be occult on radiographs, and evaluating for additional etiologies of back pain. MRI with gadolinium can be used to evaluate for malignancy. In patients with a contraindication to MRI, a bone scan can be performed with or without single photon emission computed tomography (SPECT) for more precise localization. Infrequently, comparison radiographs or computed tomography (CT) demonstrating an interval fracture correlating with acute symptoms can be sufficient.

Multiple classification systems for vertebral body fractures exist, but one commonly utilized system is the AOSpine classification which dichotomizes fractures into those that violate the endplates (e.g., wedge or split fractures) or posterior cortex (e.g., burst fractures).⁷The AOSpine classification system facilitates consistent image interpretation between providers.

Nonoperative Management

Nonoperative management includes the use of bisphosphonates, calcium supplementation, and vitamin D. Additional modifiable risk factors should be addressed, such as tobacco and alcohol use.²⁴The prescribed pain regimen is highly variable between physicians based on low-quality evidence, but randomized controlled trials suggest better outcomes with diclofenac and tramadol than with oxycodone.⁸Bracing typically involves a thoracolumbosacral (TLSO) brace for 8 to 12 weeks with follow-up radiographs to evaluate fracture healing. A randomized controlled trial found no difference in type of brace used whether custom hard brace, custom elastic brace, or ready-made elastic brace.⁹Risks of bracing in compliant patients include pressure sores, decreased pulmonary capacity, and muscular atrophy. It should be acknowledged that patients may be noncompliant with bracing due to discomfort.

Vertebral Body Augmentation

The most common indication for vertebroplasty and kyphoplasty is symptomatic VCF refractory to nonoperative management. The trial of nonoperative management is traditionally 6 weeks corresponding to the natural history of disease and inclusion criteria for clinical trials. However, delaying intervention may lead to more modest benefits from vertebral body augmentation.

Absolute contraindications include infection, whether systemic or local, as well as uncorrectable coagulopathy, and allergy to PMMA.¹⁰Relative contraindications include nerve or cord compression. Within these practice parameters, the complication rate from vertebral body augmentation is <1% for osteoporotic VCF and <5% for malignant VCF.¹⁰Clinical success rate defined as improvement in pain, disability, or quality of life is 80 to 98% for osteoporotic VCF and 70 to 92% for malignant VCF.¹⁰

Any discussion of vertebral body augmentation must acknowledge the conflicting evidence supporting its use. The original negative randomized controlled trials comparing vertebroplasty to sham procedures were published in 2009. In the first trial by Buchbinder et al, criticisms include a small sample size of 78 patients, a high proportion of subacute and chronic VCF, and a perceived small volume of injected cement.¹¹¹²In the INVEST trial with more robust sample size, criticisms include a high crossover rate, low pain score required for enrollment, lack of MRI for enrolled patients, as well as similar criticisms to the study by Buchbinder et al.¹²¹³The most recent negative trial comparing vertebroplasty to sham procedure is the VERTOS IV trial from 2018 which improved upon the methodology in INVEST, including requiring MRI evidence of acute fracture and symptoms not more than 9 weeks in chronicity with a minimum pain score of 5 out of 10.¹⁴Although not statistically significant, the greatest benefit was seen in patients with fractures less than 3 weeks old.

Positive trials comparing vertebroplasty to nonoperative management include the VERTOS II trial from 2009 and the VAPOR trial from 2016. The VERTOS II trial demonstrated immediate and durable pain relief from vertebroplasty with 12-month follow-up.¹⁵The VAPOR trial compared vertebroplasty against sham procedure mostly for inpatients with acute fractures confirmed by MRI or bone scan and treated with larger volumes of cement than prior negative studies.¹⁶Criticisms include majority of patients from a single institution as well as confounding by not anesthetizing periosteum in the sham group.¹²Likely due to the number of inpatients enrolled in VAPOR, the mean fracture age in VAPOR was 2.8 versus 6.1 weeks in the VERTOS IV trial.¹⁴¹⁶

Table 1provides a synopsis of all randomized controlled trials on vertebroplasty.

On balance, patients most likely to benefit from vertebral body augmentation are those with severe pain refractory to nonoperative management who are offered intervention within 3 weeks.

Two recent trials compared vertebroplasty with kyphoplasty, including KAVIAR in 2014 and Evans et al in 2016.¹⁷¹⁸The KAVIAR trial was terminated early due to poor enrollment with similar 12-month outcomes between the two interventions, although kyphoplasty trended toward decreased cement extravasation and decreased adjacent level VCF.¹⁷Evans et al reported equivalent pain score and disability score between vertebroplasty and kyphoplasty at 12 months of follow-up.¹⁸

Technique

Vertebral augmentation can be performed under conscious moderate sedation or with deep/general anesthesia, depending on patient selection. The patient is positioned prone and the skin is sterilely prepared in standard fashion. If the patient is under conscious sedation, confirmation of focal tenderness at the level of the VCF using fluoroscopy is done by some operators. Antibiotic prophylaxis for skin flora is recommended by SIR.¹⁹The superficial soft tissues and periosteum are anesthetized. Local anesthetic selection is operator dependent as the LABEL trial found that subcutaneous lidocaine and periosteal bupivacaine are ineffective analgesia for painful VCF, potentially due to the short half-life of the local anesthetic and paucity of periosteal nerve fibers.²⁰Transpedicular or parapedicular access is then obtained, typically with an 11-gauge access cannula for the lumbar spine and a 13-gauge access cannula for the thoracic spine. Transpedicular access is more commonly utilized, but this approach can be difficult if the patient has small pedicles, if the vertebral body is severely compressed, or if planned implantable devices need larger delivery cannula. Parapedicular access facilitates delivery of large implantable devices and permits angulation of the access needle toward the center of the vertebral body. Parapedicular access is more difficult in the upper thoracic spine where the ribs limit needle angulation as well as in the lower lumbar spine where larger pedicles facilitate or necessitate transpedicular access.²¹Care is made to advance the cannula in the anteroposterior projection to ensure the medial margin of the pedicle is not crossed before the cannula has entered the posterior cortex on the lateral projection. This ensures that the cannula does not violate the spinal canal or thecal sac. The decision to obtain unipedicular access versus bipedicular access depends on provider preference and patient anatomy. The goal of cement injection is to extend cement from the anterior cortex to the posterior one-third of the vertebral body, as well from superior endplate to inferior endplate, and between the medial margin of each pedicle.¹⁶Fracture pattern and early cement extravasation may prevent optimal cement filling.

For vertebroplasty, cement is injected into the fractured vertebra without attempting to reduce the fracture (Fig. 1a–e). For kyphoplasty, an intraosseous balloon is inflated for vertebral height restoration as well as to reduce the pressure required to inject the cement, which has been demonstrated to reduce extravasation (Fig. 2a–f). Data have suggested increased complication profile with kyphoplasty, possibly owing to larger access systems. Randomized controlled trials and meta-analysis of available data have demonstrated that vertebroplasty and kyphoplasty have equivalent pain improvement.^17182223Compared with traditional kyphoplasty, implantable devices can further facilitate fracture reduction and vertebral height restoration.²⁴

Complications and Management

Major complications after vertebroplasty or kyphoplasty occur in fewer than 1% of patients, although the risk of complications increase if a VCF is due to malignancy rather than osteoporosis.¹⁰¹²Up to 72% of patients have PMMA leakage on postprocedure CT, which is usually asymptomatic.¹⁵Less than 1% of patients have PMMA leak into adjacent veins and result in pulmonary embolus, and these emboli tend to be small and distribute peripherally in the lung and, therefore, usually require no additional intervention. Between 1 and 2% of patients have PMMA leak posteriorly through fracture clefts causing nerve root or cord impingement resulting in neurosurgical consultation. Leakage can be minimized by slowly injecting PMMA, especially at the beginning when the cement is less viscous. If leakage is seen, wait for 30 to 60 seconds for the PMMA to harden before redirecting the cannula. At the conclusion of the case, the stylet should always be inserted into the access cannula before withdrawing the cannula to prevent leakage, tracking, or cement tail.²⁵

Other complications relate to procedural trauma, such as bleeding or pneumothorax. If there is epidural hematoma resulting in cord compression, immediate neurosurgical consultation is recommended. Pneumothoraces can be monitored clinically and with serial imaging or with a chest tube if enlarging or symptomatic.

Infection can result in discitis-osteomyelitis which can be minimized with routine use of antibiotics that cover skin flora. These cases are typically managed with long-term intravenous antibiotics, although neurosurgical intervention could be required if the case is complicated by epidural abscess. The risk is increased in patients who are immunosuppressed or who have had recent infections. As of yet, there is no clear role for prophylactically mixing PMMA with antibiotics.²⁶

An examination of the Food and Drug Administration Manufacturer and User Facility Device Experience (MAUDE) database demonstrated five procedural deaths attributed to PMMA allergy in more than 200,000 procedures.²⁷

Transient hyperalgesia is another rare complication (less than 3%) characterized by early pain recurrence, possibly due to inflammation from the exothermic reaction from PMMA polymerization, and is treated with steroids and nonsteroidal anti-inflammatory drugs.²⁸

Postprocedural Follow-up

Generally, postprocedure pain relief is immediate, although maximal relief may be delayed up to 1 month.¹¹¹⁴¹⁵Patients should be evaluated for neurologic compromise after the procedure. Postprocedure observation for 2 hours is typical prior to discharge, but the patient's disposition depends on recovery from sedation and pain tolerance. Follow-up imaging is not routinely used but may include standing radiographs to evaluate for interval adjacent level compression fractures, whether due to systemic osseous disease or altered biomechanics from the intervention. VERTOS II demonstrated in randomized fashion that there was no difference in adjacent level fractures when comparing vertebroplasty to conservative management.¹⁵Newer meta-analyses of randomized controlled trials also found no increased risk of adjacent level fractures following vertebroplasty.²⁹³⁰Together, these high-quality data support the theory that the natural history of patients with VCF is an increased risk of future fractures regardless of intervention.

Conclusion

In appropriately selected patients with acute symptomatic VCF, vertebroplasty and kyphoplasty are effective and safe procedures to mitigate pain and improve quality of life. The ideal patient has clinical and imaging evidence of a VCF less than 3 weeks old and is refractory to nonoperative management. Contraindications are few but include significant retropulsion, active infection, or nerve or cord compression. Randomized controlled trials and meta-analyses have not shown statistically significant differences in outcomes between vertebroplasty and kyphoplasty. Newer implantable devices and augmentation procedures may improve efficacy, but robust data are currently lacking.

Footnotes

References