When caring for spine patients, accurate diagnosis is essential, as interventional treatments are only effective when the true pain generator is correctly identified. Diagnostic procedures generally fall into provocative tests, which reproduce pain, and analgesic blocks, which relieve pain through anesthetic injections. However, both approaches are limited by false positives, particularly with uncontrolled medial branch or sacroiliac blocks. Controlled comparative blocks improve accuracy, but predictive value remains modest unless combined with history, examination findings, and imaging. This principle underlies the broader theme of interventional spine care: technical skill alone is insufficient; outcomes depend on diagnostic precision and careful patient selection.
Key points
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Accurate diagnosis is critical in interventional spine care; outcomes depend on matching treatment to the correct pain generator.
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Diagnostic procedures include provocative tests (reproducing pain) and analgesic blocks (relieving pain), but both risk false positives without careful integration of history, examination, and imaging.
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Epidural steroid injections are most effective for radicular pain, while sacroiliac joint injections and medial branch blocks with radiofrequency ablation target the sacroiliac joint and facet-mediated pain, respectively.
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Basivertebral nerve ablation, expandable vertebral implants (eg, SpineJack), and endoscopic spine surgery represent advanced, evidence-based techniques expanding treatment options.
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Emerging approaches emphasize minimally invasive, durable interventions that bridge conservative management and traditional surgery.
Abbreviations
| BVN | basivertebral nerve |
| BVNA | basivertebral nerve ablation |
| ESI | epidural steroid injection |
| FBSS | failed back surgery syndrome |
| PPV | positive predictive value |
| RFA | radiofrequency ablation |
| SI | sacroiliac |
| VCF | vertebral compression fracture |
Interventional strategies for pain management
Introduction
Back pain is one of the most common reasons patients seek medical care and remains a leading cause of disability in the United States. Combined with other musculoskeletal disorders, it contributes significantly to societal and economic burden—estimated between $560 and $635 billion annually. Effective management depends on accurate assessment and diagnosis to guide treatment, improve outcomes, optimize resource utilization, and reduce costs.
Pain may arise from various spinal and paraspinal structures, including muscles, tendons, ligaments, bones, nerves, zygapophyseal (facet) joints, sacroiliac (SI) joints, and intervertebral discs. Back pain is commonly categorized as axial or radicular, with chronic axial pain typically originating from the intervertebral discs, Z-joints, or SI joints. Emerging evidence also suggests vertebral endplates may contribute to discogenic pain, although no diagnostic technique currently isolates endplate pathology from other disc-related sources.
This article presents a comprehensive overview of diagnostic strategies and image-guided interventional procedures used to evaluate and manage spinal pain, along with an outlook on emerging therapies in interventional pain medicine.
Guiding Principles in Interventional Spine Care
The cornerstone of spine pain management is identifying the underlying pain generator. This begins with a thorough clinical evaluation, including the following:
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History: Focused on distinguishing axial versus radicular pain, pain quality (eg, aching, burning), exacerbating or relieving factors, and neurologic symptoms (numbness, tingling, weakness).
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Physical Examination: Assessing range of motion, motor strength, sensation, reflexes, and special tests such as Spurling’s, straight leg raise, and facet loading maneuvers.
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Imaging:
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Radiographs are useful for evaluating alignment, spondylolisthesis, compression fractures, disc height loss, and facet arthropathy.
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MRI offers superior visualization of soft tissue structures including disc herniations, stenosis, and endplate signal changes.
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Adjunctive Testing: Electrodiagnostic studies and diagnostic injections may be used when clinical and imaging findings are inconclusive.
Treatment Framework
Management typically begins with conservative care—physical therapy, pharmacologic agents, and modalities such as heat, ice, or stretching. When these measures are insufficient, image-guided interventional procedures may be indicated. These procedures serve both diagnostic and therapeutic purposes, allowing clinicians to confirm pain generators and deliver targeted treatment.
Interventional techniques have been shown to be safe and effective for many spinal pain conditions and are an essential component of a multimodal treatment plan. As technology advances, new tools and techniques continue to expand the frontiers of interventional pain medicine, offering additional options for patients with chronic spinal pain.
Principles of diagnostic procedures
In spine care, diagnostic procedures are generally categorized as provocative or analgesic.
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Provocative procedures aim to reproduce the patient’s typical pain by mechanically or chemically stimulating a suspected pain generator. If the provoked pain matches the patient’s characteristic symptoms, the structure is presumed to be the source.
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Analgesic procedures involve selectively anesthetizing the suspected pain source—either directly or via its innervating nerves—with a local anesthetic. Relief of pain suggests the anesthetized structure may be the pain generator.
Both techniques have limitations. False positive results are a known issue and can reduce diagnostic accuracy. For instance, uncontrolled lumbar medial branch blocks have demonstrated false positive rates ranging from 25% to 41%. ,
To address this, controlled comparative blocks are used. This involves 2 separate injections using anesthetics with different durations of action, typically a short-acting agent (eg, lidocaine) and a long-acting agent (eg, bupivacaine). A positive diagnostic result is defined as pain relief that matches the expected duration of action for each anesthetic. This technique has a reported sensitivity of 100% and specificity of 65%.
However, even with high-quality testing, diagnostic certainty is not guaranteed. Clinicians must consider the positive predictive value (PPV) the probability that the patient truly has the condition when the test is positive. PPV depends on 3 factors: test sensitivity, test specificity, and the prevalence of the condition in the tested population:
For example, if zygapophyseal (Z) joints account for only 30% of chronic low back pain cases, even with a positive comparative medial branch block, the PPV is about 55%. This means that in nearly half of cases, pain may originate from another source despite a positive result.
The issue is even more pronounced with SI joint pain. If the prevalence is only 18% and dual comparative blocks have similar sensitivity and specificity, the PPV drops to around 35%. In these cases, the test may be more misleading than informative if used in isolation ( Fig. 1 ).
Probability curves by prevalence.
The most effective way to improve PPV is to increase the pretest probability—in other words, selectively test patients in whom the suspected condition is more likely to be present. This can be accomplished by integrating clinical features, including.
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A focused history that aligns with known pain patterns
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Physical examination findings that support a specific pain generator
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Imaging or functional studies that correlate with symptoms
By combining these elements before proceeding with interventional diagnostics, clinicians can enhance diagnostic yield, reduce false positives, and improve treatment targeting.
Foundational interventional treatment modalities
A variety of image-guided interventional techniques are available for treating spinal pain, each with specific indications based on the identified source of pain.
Epidural Steroid Injections
Epidural steroid injections (ESIs) are commonly used for radicular pain resulting from nerve root compression or inflammation, such as in cases of disc herniation or spinal stenosis. Corticosteroids aim to reduce perineural inflammation and improve pain. However, efficacy is most evident in patients with confirmed radicular symptoms, and results may be limited or inconsistent in cases of nonspecific back pain. ,,
Sacroiliac Joint Injections
The SI joint is a recognized contributor to lower back pain, particularly in patients with post-traumatic changes, pregnancy-related instability, or following lumbar fusion. Intra-articular injection of anesthetic and corticosteroid can provide both diagnostic confirmation and therapeutic relief. Evidence suggests that accurate diagnosis via diagnostic blocks significantly improves the success of therapeutic injections ,,, [5].
Medial Branch Blocks and Radiofrequency Ablation
Facet-mediated pain is addressed by targeting the medial branch nerves that innervate the zygapophysial joints. A positive response to medial branch blocks is required before proceeding to radiofrequency ablation (RFA), which uses thermal energy to interrupt nociceptive transmission. Studies show that outcomes are most favorable when patients are carefully selected using controlled diagnostic blocks. ,,,,
Matching Treatment to Diagnosis
Interventional treatments for spine pain are not universally effective and must be applied judiciously. A therapy that is highly effective for one pain generator may be ineffective—or even harmful—if misapplied to a different etiology. For instance, performing RFA in a patient with discogenic pain rather than facet-mediated pain is unlikely to yield benefit and may expose the patient to unnecessary risk. This reinforces the principle that interventional success is dependent not only on technical skill, but also on diagnostic accuracy. ,
Moreover, the use of image guidance (typically fluoroscopy or ultrasound) is critical in ensuring accurate needle placement and minimizing complications. This enhances both diagnostic and therapeutic reliability across procedures.
The cutting edge
Advanced interventional procedures are reshaping the landscape of spine care by extending beyond traditional injections and ablative techniques to address complex pain and structural pathology. While the list of procedures that qualify for this list is growing rapidly, this section will focus on a few.
Basivertebral nerve ablation (BVNA) has emerged as a targeted treatment for vertebrogenic low back pain, providing durable relief in carefully selected patients. Vertebral augmentation with expandable implants, such as intravertebral devices, offers enhanced restoration of vertebral height and alignment compared to traditional balloon kyphoplasty. Endoscopic spine surgery (ESS) further blurs the boundaries between interventional pain management and open surgery, allowing for minimally invasive decompression and targeted discectomy with reduced tissue disruption. Together, these procedures reflect a growing spectrum of therapies that complement and bridge the gap between nonoperative interventions and traditional surgery, advancing precision and durability in the treatment of spine-related pain.
Management of vertebral fractures
Vertebral compression fractures (VCFs) are among the most common consequences of osteoporosis, although they may also result from trauma or neoplastic disease. They occur most frequently at the thoracolumbar junction, where mechanical loads are greatest. Patients typically present with acute, movement-related pain, which can lead to immobility, deconditioning, and significant reductions in quality of life.
Conservative treatment strategies—such as bed rest, physical therapy, and bracing—may provide symptomatic relief but are often inadequate. Prolonged immobility in this setting contributes to muscle wasting, progressive kyphosis, and loss of independence. These limitations have driven interest in interventional techniques, particularly vertebroplasty and balloon kyphoplasty, which are designed to stabilize fractures and restore vertebral body integrity.
Evolution of Vertebral Augmentation
Vertebroplasty involves the percutaneous injection of polymethylmethacrylate cement into the fractured vertebra, primarily for pain relief and stabilization. Balloon kyphoplasty modifies this approach by inserting an inflatable tamp to create a cavity and restore partial vertebral height before cement injection.
The evidence for these procedures has been mixed, depending on trial design. Explanatory randomized controlled trials such as those by Buchbinder and Kallmes found little difference between vertebroplasty and sham procedures. In contrast, pragmatic randomized trials, including those by Klazen and Farrokhi, demonstrated clear improvements in pain and function compared with conservative management. Balloon kyphoplasty trials, including Wardlaw and Boonen, similarly showed significant gains in pain reduction and quality of life.
Importance of Fracture Reduction
The correction of vertebral deformity is a central consideration in treatment. Residual kyphosis after fracture increases anterior load transmission and nearly doubles the stress placed on adjacent vertebrae during flexion, thereby predisposing patients to new fractures. Clinical studies have demonstrated that kyphotic deformity is associated with impaired mobility, higher fall risk, and greater functional decline. Katzman and colleagues linked age-related hyperkyphosis to impaired mobility in older women, while Van Meirhaeghe showed that greater correction of kyphotic deformity following kyphoplasty was associated with better outcomes. Even after augmentation, persistent deformity may predispose patients to mechanical complications, as demonstrated by Tzermiadianos and colleagues.
Taken together, these findings highlight that fracture reduction is not simply a radiographic outcome but a determinant of long-term patient function and risk.
Advances in Fracture Reduction: Expandable Implants
More recent innovations in vertebral augmentation aim not only to stabilize fractures but also to optimize reduction and alignment. The SAKOS clinical trial compared the SpineJack system, a mechanical implant designed to restore vertebral height, with balloon kyphoplasty in patients with osteoporotic VCFs.
The study demonstrated that SpineJack achieved superior vertebral height restoration and kyphotic angle correction, which translated into improved clinical outcomes. Patients treated with SpineJack experienced greater reductions in pain and disability scores at both 6 and 12 months. The trial also revealed a lower incidence of adjacent level fractures in the SpineJack cohort compared with balloon kyphoplasty. Procedural times were similar between groups, although SpineJack required a smaller cement volume, which may further reduce complications ( Fig. 2 ).
The SpineJack implant before and after expansion.
(Reproduced from C. Renaud, Treatment of vertebral compression fractures with the cranio-caudal expandable implant SpineJack®: Technical note and outcomes in 77 consecutive patients, Orthopaedics & Traumatology: Surgery & Research, 101 (7), 2015, 857-859, https://doi.org/10.1016/j.otsr.2015.08.009 . Copyright © 2015 Elsevier Masson SAS. All rights reserved.)
Basivertebral nerve ablation
BVNA is an emerging interventional technique used to manage chronic vertebrogenic low back pain by targeting the basivertebral nerve (BVN), which innervates the vertebral endplates. BVNA has garnered increasing attention due to accumulating evidence supporting its efficacy and safety profile in well-selected patient populations.
Indications
The primary indication for BVNA is chronic axial low back pain of vertebrogenic origin, typically persisting for more than 6 months and refractory to conservative management including physical therapy, pharmacologic agents, and activity modification. Crucially, patients must demonstrate Modic type 1 or 2 endplate changes on MRI (particularly in the L3–S1 region), which serve as imaging biomarkers of vertebrogenic pain mediated by the BVN. ,,
Modic changes are categorized as follows:
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Type 1: Hypointense on T1-weighted and hyperintense on T2-weighted MRI, indicative of bone marrow edema and inflammation.
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Type 2: Hyperintense on both T1-and T2-weighted MRI, representing fatty marrow replacement.
These changes reflect endplate disruption and neuroinflammatory processes, which activate nociceptive fibers of the BVN, making them key targets for thermal RFA. , ( Fig. 3 ).
MRI images of Modic type 1 changes and Modic type 2 changes.
(Ole Kudsk Jensen et al., Type 1 Modic changes was a significant risk factor for 1-year outcome in sick-listed low back pain patients: a nested cohort study using magnetic resonance imaging of the lumbar spine, The Spine Journal, 14 (11), 2014, 2568-2581, https://doi.org/10.1016/j.spinee.2014.02.018 .)
Contraindications include spinal instability, radicular symptoms suggestive of nerve root compression, severe spinal stenosis, and absence of Modic changes.
Prognosis
Clinical studies have consistently demonstrated significant improvements in pain and functional outcomes following BVNA in appropriately selected patients. In a randomized controlled trial by Fischgrund and colleagues, patients undergoing BVNA reported a mean 44-point reduction in Oswestry Disability Index scores and a mean 4.4-point reduction in visual analog scale pain scores at 24 months postprocedure, compared to minimal improvements in the sham control group.
Long-term follow-up studies suggest that these improvements are durable for at least 5 years, with sustained benefits in both pain and function without the need for repeat interventions. , Importantly, BVNA is associated with low complication rates, with no reported cases of permanent neurologic injury or vertebral instability.
Patient Phenotype
A distinct phenotype has emerged for patients most likely to benefit from BVNA. These individuals typically present with the following:
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Nonradicular, midline low back pain, worsened by sitting, bending, and activity, and relieved by recumbency.
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Pain duration of ≥6 months, resistant to conservative management.
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Modic type 1 or 2 changes at one or more vertebral levels between L3 and S1.
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Absence of significant facet-mediated or discogenic pain (eg, based on physical examination and/or diagnostic blocks).
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Age between 30 to 70 years, with or without a history of prior lumbar disc degeneration.
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Normal or mildly reduced sagittal alignment and no evidence of dynamic instability.
Patients with depression or high pain catastrophizing scores may have less favorable outcomes, although these are not absolute contraindications.
BVNA is thus best suited for patients who fall within this phenotype, as identification of vertebrogenic pain generators remains key to procedural success ( Fig. 4 ).
