Indications and limitations
Spinal bone biopsy is necessary for numerous clinical tasks. The primary goal is to determine the nature of an unclear solitary bone lesion or to confirm metastatic disease in patients with a previously established oncological diagnosis (or to find the source in an unknown primary tumor). The procedure is also ordered to rule out multiple myeloma in compression fractures.
In infectious diseases, biopsy allows for the precise identification of the causative agent in spondylodiscitis (spondylodiscitis) or osteomyelitis (osteomyelitis). Occasionally, the intervention is performed before vertebroplasty for medico-legal reasons.
Absolute contraindications include:
- Uncorrectable coagulopathy.
- Inability of the patient to communicate and cooperate.
- Hypervascular lesions in the cervical and thoracic segments.
- Anatomically complex or unsafe target location.
- High risk of spreading infection into healthy bone.
Anatomical approaches and visualization
Navigation is critical for safe needle advancement. Fluoroscopy (X-ray) remains the primary method. CT is often used as an adjunct for complex locations. CT fluoroscopy is generally avoided in routine practice due to high radiation exposure, especially during access to C1.
The choice of approach depends on the spinal level:
- Lumbar spine: transpedicular (transpedicular) or posterolateral (posterolateral) route.
- Thoracic spine: intercostovertebral (intercostovertebral) approach.
- Cervical spine: anterolateral (anterolateral) approach with manual displacement of major neck vessels.
- C1 and dens (dens): accessed transorally (oropharyngeal approach).
- Posterior elements and pedicles: punctured via a posterior oblique approach under CT guidance.
Selection of instruments and tissue sampling
To increase diagnostic yield, it is best to target mixed sclerotic-lytic areas or contrast-enhancing lesions. Hypodense or cystic areas should be avoided, as necrotic masses often accumulate there.
Needles are selected according to tissue density:
- Trephine biopsy needles (11–15-G): used to obtain a core of bone marrow. Inserted through a cannula driven into the cortical layer.
- Cutting needles (16–20-G): used for core biopsy of the soft tissue component.
- Fine-needle aspiration (20–22-G): Chiba needles are sufficient for aspirating fluid from discs or for the cytological assessment of metastases.
For dense vertebrae (with marked osteosclerosis), automated battery-powered drills are used. A combined approach is frequently employed: trephine biopsy for histology supplemented by aspiration for microbiology.
Safety technique using the lumbar vertebra as an example
Consider the transpedicular approach to the L3 vertebral body. The patient is placed in the prone position (prone position). A 10-G trocar is directed into the left pedicle (pedicle).
Critical safety checkpoints:
- The needle must not penetrate into the inferior intervertebral foramen (foramen) to avoid injuring the spinal nerve.
- The needle must not breach the medial wall of the pedicle—this prevents the formation of an epidural hematoma and injury to the dural sac (thecal sac).
After the trocar reaches the posterior margin of the vertebral body, a 12-G needle with a drill is inserted, and a 2–3 cm core of cancellous bone (cancellous bone) is harvested. This volume is sufficient for an accurate diagnosis (e.g., plasmacytoma).
Diagnostic features of various pathologies
It is recommended to perform more than three needle passes. Accuracy depends on the tumor type:
- Metastases and infections are the easiest to diagnose; fine-needle aspiration is often sufficient.
- Lymphoma requires multiple core biopsies.
- Primary bone tumors (e.g., osteoblastoma) require a full trephine biopsy.
Important oncological rule: if radical tumor resection is planned, the needle trajectory must not pass through uninvolved anatomical compartments (compartments) to avoid their contamination.
Briefly: answers to topical questions
What microorganisms are the most frequent causative agents of infectious spondylodiscitis?
The most common causative agent of infectious spondylodiscitis is hematogenous Staphylococcus aureus. Tuberculous and, rarely, fungal etiologies such as Candida are also described in vertebral osteomyelitis.
What is the average effective radiation dose (in mSv) for the patient and physician during a CT fluoroscopy-guided vertebral biopsy?
The sources do not provide numerical values for the effective radiation dose in mSv for the patient or physician during vertebral CT fluoroscopy.
Oncological access rule: "Do not contaminate clean compartments." When biopsying a potentially resectable tumor, the needle must pass only through tissues that will subsequently be excised along with the neoplasm.
Class and exam questions
Why does biopsy in spondylodiscitis frequently yield a false-negative result?
The accuracy of a biopsy of an infected disc is only about 50%, and the false-negative culture rate exceeds 60%. To increase bacterial yield, empirical antibiotic therapy must be discontinued 24–48 hours before the procedure.
What is the danger of biopsy in renal cell carcinoma metastases?
These tumors, like hemangiomas, are heavily vascularized. Puncture can provoke severe bleeding and hematoma, leading to compressive neurological complications.
Why are tissues manually shifted during a cervical approach?
During the anterolateral approach to the cervical vertebrae, the physician manually retracts the major vessels (carotid artery and jugular vein) to clear a safe corridor for advancing the needle under X-ray guidance.
What else to study on this topic
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