Computed Tomography (CT) in Traumatology
Computed tomography plays a crucial role in analyzing complex bone anatomy. The method offers several significant advantages for diagnosing injuries and pathologies of the musculoskeletal system:
- Three-dimensional reconstruction: the scanner generates a volumetric image based on multiple slices. This is critically important in burst or comminuted fractures, where the physician needs to spatially assess the location of bone fragments. The method is indispensable for injuries involving complex anatomy: the spine, pelvis, facial bones, hand, foot, and ankle joint.
- Absence of the summation effect: unlike conventional X-rays, where the shadows of structures overlap, CT allows for clear visualization of the scapula, sacrum, and pelvis. This aids in detecting intraosseous cavities (such as cysts or foci of infection) and tumors.
- Quantitative analysis: scanning makes it possible to reliably measure bone tissue density, which helps detect metabolic disorders and areas of osteoporosis.
- Navigation and intra-articular diagnostics: CT is used as a visual guidance method during puncture aspiration biopsy. Additionally, tomography excels at detecting loose bodies in the spinal canal or joint cavity.
Despite its high information yield, CT has disadvantages. These include poor soft tissue differentiation and a significant radiation dose, especially when examining a large area with overlapping slices. Furthermore, the presence of metal implants (screws, pins, endoprostheses, plates) provokes severe artifacts that drastically reduce image quality.
Capabilities of Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging operates on an entirely different principle — it is based on nuclear magnetic resonance (the re-emission of a high-frequency signal by protons or neutrons in a magnetic field). The scanner includes a magnet, gradient and radiofrequency coils (acting as a transmitter and receiver), as well as a computer system with high-capacity storage.
MRI is considered the ideal tool for evaluating the musculoskeletal system due to the high contrast of signals from various tissues. It provides superb differentiation of ligaments, tendons, muscles, nerves, blood vessels, hyaline cartilage, as well as cortical and trabecular bone.
- Occult injuries: MRI is capable of detecting microfractures of the trabecular bone and contusions that remain completely invisible on CT and conventional radiographs.
- Joint pathology: to date, this is the most informative method, which has almost completely replaced X-ray arthrography.
- Spine diagnostics: the number one method for detailed study of spinal nerve roots, intervertebral discs, and the spinal cord itself in injuries or diseases.
Additionally, MR angiography can be used to visualize blood vessels and build their 3D models (for example, to assess tumor vascularization or blood circulation in limb injuries). Intra-articular and intravenous contrast enhancement are also available.
Disadvantages of MRI: the method is contraindicated in patients with vascular clips or pacemakers. The examination is poorly tolerated in cases of claustrophobia. The presence of metal in the body leads to distortion of the magnetic field and signal loss, causing characteristic 'holes' to appear on the image.
Examination of the Neuromotor Apparatus: EMG and ENMG
Electrophysiological methods are used for an in-depth study of the nervous and muscular systems. Potentials are recorded using needle or surface electrodes.
- Electromyography (EMG): a method for analyzing and recording the bioelectrical activity of muscle fibers themselves.
- Electroneuromyography (ENMG): the study of evoked potentials of the nerve and muscle that occur in response to their electrical stimulation.
These studies help clarify the nature of peripheral innervation disorders, determine the true causes of muscle atrophy, monitor the state of the neuromotor apparatus dynamically, and assess the effectiveness of ongoing rehabilitation measures.
Invasive Methods: Puncture and Biopsy
In addition to diagnostic imaging, invasive techniques are widely used in orthopedics, involving the introduction of an instrument or needle through intact tissues.
Puncture can be diagnostic or therapeutic-diagnostic. A physician can puncture joints, bones, cerebral ventricles, soft-tissue cavities (cysts, abscesses, hematomas), and body cavities. The main goal is to obtain contents (punctate) for laboratory analysis and visual inspection.
Joint puncture is of particular importance in hydrarthrosis (excess fluid in the joint cavity). The type of fluid indicates the nature of the pathology: blood signifies hemarthrosis, pus signifies purulent arthritis, and an accumulation of synovial fluid signifies synovitis.
Visual assessment of the punctate is extremely vital:
- If fat droplets are visible in the blood, this is an indirect sign of an intra-articular fracture.
- An admixture of synovial fluid in the blood indicates that the injury occurred some time ago.
- Turbid fluid with flakes indicates infection (normally, synovial fluid is straw-colored and transparent).
Laboratory analysis of the punctate (cytology, culture) reveals specific and non-specific processes (e.g., tuberculosis, gonorrhea), as well as enzymes and mineral salts. The therapeutic effect of a puncture lies in removing excess fluid: this reduces the tension of the joint capsule, which rapidly relieves the pain syndrome and increases the range of motion.
For the definitive objective confirmation of the diagnosis, a morphological study is performed. The required material is obtained via biopsy from a wound, skin surface, mucous membranes, or intraoperatively after tissue dissection.
Briefly: answers to topical questions
Which structures of the musculoskeletal system are appropriate to examine using ultrasound?
Ultrasound examination is appropriate for assessing the condition of soft tissues and joints.
- Soft tissues — examination of muscles, tendons (especially the Achilles tendon), and diagnosis of soft-tissue tumors (e.g., hemangiomas).
- Joints — detection of fluid in the joint cavity and periarticular zone (synovitis), popliteal cyst (Baker's cyst), ligament and meniscus injuries.
- Hip joint in children — assessment of the relationship between the femoral head and the acetabulum (the method of choice in pediatrics).
What are the absolute and relative contraindications for MRI?
Absolute and relative contraindications or limitations for magnetic resonance imaging include the presence of pacemakers, vascular clips, certain implantable electronic devices, ferromagnetic foreign bodies in the patient, and claustrophobia.
- Electronic implantable devices — pacemakers, middle ear implants, insulin pumps.
- Ferromagnetic foreign bodies — fragments inside or near the eyeball, cerebral vessel clips; MRI is also unsuitable for patients with ferromagnetic stents.
- Claustrophobia — the examination is performed in a enclosed chamber.
Modern MR-compatible models of certain devices make it possible to perform the examination.
What types of biopsy are used in traumatology and orthopedics to obtain morphological material?
Biopsy techniques are used to obtain morphological material, including puncture, trephine, and open tissue harvesting methods.
- Fine-needle aspiration biopsy — a rapid, minimally invasive procedure; it can be performed under palpation, ultrasound, or CT guidance and is often used in conjunction with cytological examination.
- Core needle biopsy — a thick-needle biopsy; sources also mention trephine biopsy of the spine and pelvic bones under CT guidance.
- Open biopsy techniques involve surgical tissue sampling; material for morphological examination can be obtained from the skin surface, wounds, mucous membranes, as well as from tissues after their incision, including intraoperatively.
What are the normal physicochemical and cytological characteristics of synovial fluid?
According to the cited sources, normal synovial fluid is described on visual assessment as clear and straw-colored. For osteoarthritis, it is noted that synovial fluid has normal viscosity, a cell count of no more than 5 × 10³ per 1 mm³, and a neutrophil count during synovitis of no more than 50%.
What complications can occur during diagnostic joint puncture?
The primary complication of diagnostic joint puncture is the risk of infectious complications.
- Infectious complications may occur if rules of asepsis and antisepsis are not observed.
- Performing a puncture of the knee or any other joint outside a hospital setting is strictly prohibited due to the high risk of infectious complications.
- During joint puncture, it is essential to strictly observe the rules of asepsis and antisepsis to prevent infectious complications.
Class and exam questions
How to determine an intra-articular fracture from joint aspirate?
An indirect sign of an intra-articular fracture is the presence of fat droplets in the blood (hemarthrosis) obtained during joint cavity puncture.
Why do metal implants interfere with CT and MRI scans?
In CT, metal causes unwanted artifacts that reduce image quality. In MRI, metal objects distort the signal and lead to signal voids ("holes") around the implant.
What else to study on this topic
- Specific features of contrast-enhanced MRI in the musculoskeletal system.
- Principles of interpreting laboratory and cytological studies of joint aspirate.
- Technique for CT-guided fine-needle aspiration biopsy.
- Assessing rehabilitation efficacy using electroneuromyography (ENMG).
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