Shoulder Imaging: Key Concepts & Considerations

• Diagnostic imaging is an important aspect of musculoskeletal radiography.
• Interpret image with radiologist, ortho.

Review

• Understand the different imaging modalities.
• Know the benefits and risks of each modality.
• Results of imaging should correlate to clinical findings.
• Imaging results affect the PT plan of care.
• Ability to order imaging is expanding.
• Daily interpretation of findings is necessary.

Types of Imaging

• Radiographs: cheap, easy, fast, and involve radiation.
• CT Scan: fast, radiation involved, but limited soft tissue visualization.
• MRI: expensive, longer wait time, but good for visualizing soft tissue.
• Bone scan: useful for detecting metastatic disease, involves radiation.
• Ultrasound: dependent on equipment and user skill, good for muscle imaging and guidance.
• Fluoroscopy: portable, dynamic, and involves radiation.
• DEXA scan: used for bone density assessment.

Radiology Terms

• Radio-opaque substances appear white on imaging and have high density and absorption (Metal > Bone > Soft tissue > Fat > Air).
• Radiolucent substances appear black.
• Sclerosis appears as relative increased opacity and can indicate osteoarthritis and subchondral bone issues.
• Osteopenia is relative bone lucency related to non-weight bearing and osteoporosis, requiring DEXA scan for diagnosis.

Radiology Views

• Two views, at a minimum are needed, as one view, is no view.
• More than two views are needed for some conditions (3 or 4).
• Imaging order depends on the physical exam findings.
• Visualize specific structures.
• Rule conditions in or out based on view.
• Shoulder series can assess for chronic instability.
• X-rays are indicated prior to MRI.
• Radiographic OA affects clinical decisions
• Joint health can be assessed with a quick X-ray.

Common Shoulder Views

• AP View: includes internal and external rotation, and visualizes clavicle, scapula, ACJ, GHJ, and proximal humerus.
• Grashey View: an internally rotated oblique view for greater tuberosity visualization and GHJ space assessment.
• Axillary/Scapular Y View: assesses humeral head position and is used pre- and post-dislocation reduction.

Shoulder Arthritic Changes

• Joint space narrowing.
• Osteophytes.
• Subchondral sclerosis reflects increased bone density, appearing radio-opaque.
• Subchondral cysts.
• High riding humerus may result from RC deficiency.
• Acetabularization involves acromion and concave deformity.

Common Views of the Knee

• AP: weight bearing vs. non weight bearing, and joint space and alignment.
• Lateral: patellar alignment (alta/baja) and joint space, and effusion.
• Tunnel: visualizes the intercondylar notch and posterior condyles.
• Sunrise: lateral patellar alignment and PFJ.

Knee Osteoarthritis

• May present with varus deformity and osteophyte formation.

Patella Alta

• Patella Alta displays high riding patella and instability due to patellar tendon rupture.

Tunnel View

• Assesses WB or NWB of intercondylar notch, OA changes, and loose bodies.

Merchant View

• Requires 45 degrees flexion and Sunrise requires max flexion for patellar alignment.
• Sulcus angle indicates depth of the patellar sulcus.
• Congruence angle is defined as the patella within sulcus
• Congruence angle ranges -8 to +8 is normal, takaal hilt is 15

Ankle Views

• AP and True AP assesses syndesmotic region.
• True AP

Syndesmotic Injury

• Look for increased medial clear space on AP view.

Lumbar Spine

• A lateral view allows visualization of posterior, middle, and anterior columns, disc spaces, and vertebral body height, can detect spondylolisthesis – (defect in pars)
• Coned down view used to focus On L4-S1.

Lumbar Spine - AP View:

• Can detect lumbarization of the sacral vertebra or sacralization of the lumbar vertebra.

• Can detect scoliosis.

• Oblique view enables visualization to look at pars elongation or fracturing.

Scottie Dog

• Neck: Pars Interarticularis
• Front leg: Inferior Articular Facet
• Nose: Transverse Process
• Eye: Pedicle
• Body: Lamina

CT Scan (Computed Tomography)

• Axial X-ray imaging is relatively fast and easy to perform, identifies and classifies fractures.
• Less expensive than MRI.
• Radiation exposure is high.
• Limited ability to analyze soft tissue as it is dependent on density differences to contrast.
• Fluid content differences separate soft tissues.
• Better for claustrophobic patients.

MRI (Magnetic Resonance Imaging Advantages)

• Shows best visualization of soft tissue (tendons, ligaments, intervertebral disc and soft tissue mass).
• High-resolution images are useful in injury grading.
• No ionizing radiation.
• Non-invasive nature is a merit, and images can be enhanced with contrast.

MRI (Magnetic Resonance Imaging Disadvantages)

• Poor visualization of cortical bone due to wry une tuid.
• Strong magnets are sensitive to patient motion.
• Requires constant cooling with liquid helium.
• Expensive to own and operate; Long study times, causing long wait times.
• There is a need to consider weight limitations for heavier patients with limited open MRI and lower resolution is closed.
• Artifacts are produced with implants as a danger with metallic foreign bodies Lweldus or military.

Describing Images

• Plain films involve beam to cassette (AP, PA, lateral, oblique), and special views such as Sunrise.
• MRI and CT scans involve planes of body in Sagittal, coronal, and axial views.
• MRI views – T1 vs T2, PD, FS images, where fat sat (anatomy) vs fat suppressed (pathology).

Nuclear Imaging:

• Radionucleotide bone scan sensitive to changes in bone metabolism.
• Limited role in MSK medicine; widely used for metastatic concerns (cancer).
• Injection of radioactive material (small amount): 3-phase scan (while injecting, shortly after, 3-5 hours after).
• Sometimes used for suspected stress injuries, but does not impact treatment in MSK medicine.

Diagnostic Ultrasound

• Results are dependent on examiner skillset.
• Soft tissue injuries to tendon and muscle can be detected.
• Portable and relatively inexpensive.
• No ionizing radiation.
• Comparable to MRI and CT for some conditions with good equipment and a skilled examiner, although the surgeon will still require CT or MRI.
• May be used in Guided injections which warn medication release and utilized in research settings in TA recruitment.

Fluoroscopy

• Is a similar concept to Xray with image transferred to screen Can be static or dynamic and Used for fracture reduction and OR fixation:
• Can be used for stress joints or during Guided injections, but there is increased radiation with Lower quality images.

DEXA Scan

• (Dual Energy Xray Absorptiometry) measures bone density to assess Risk of osteoporosis or fracture by measuring bone density at the L-spine, proximal femur, distal radius, and calcaneus which are used as standard anatomical parts for reference to compare to normative values.
• Measures body composition used in Research applications.

Study slide

• Know the different imaging modalities.
• Know the advantages and disadvantages.
• Correlate image to clinical findings.
• Ability to order imaging is expanding.
• There exists the Purpose of different Xray views. .

Explore essential concepts in shoulder imaging, including radio-opacity, sulcus depth, and the importance of true AP views. Understand optimal views for specific defects and anatomical assessments. Learn about differential diagnoses and MRI considerations for welders.