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o Displacement and Angulation: Malalignment of bone fragments.
o Soft Tissue Swelling: May indicate underlying injury.

2. Identifying Dislocations and Subluxations

Joint dislocations occur when bones move out of their normal alignment, disrupting joint
function. Subluxations involve partial dislocation, where the joint is misaligned but still
partially in contact.

a. Common Dislocations

• Shoulder (Glenohumeral) Dislocation:
o Anterior Dislocation (most common) – The humeral head shifts forward.
o Posterior Dislocation – The humeral head moves backward, often due to seizures or
electrical shock.
• Elbow Dislocation – Typically posterior due to falling on an outstretched arm.
• Hip Dislocation:
o Posterior Dislocation (most common) – The femoral head shifts behind the acetabulum.
o Anterior Dislocation – Less common but occurs due to extreme leg hyperextension.
• Finger Dislocations – Frequently seen in sports injuries, particularly at the PIP and DIP joints.

b. Radiographic Clues of Dislocations

• Loss of normal joint congruency – Articular surfaces are misaligned.
• Empty Socket Sign – The joint socket appears vacant due to bone displacement.
• Overlapping Bones – Indicates significant misalignment or rotation.
• Associated Fractures – Common with dislocations, particularly at the shoulder and hip.
• Common Dislocations:
o Shoulder (glenohumeral dislocation, anterior vs. posterior)
o Hip (posterior dislocation common in trauma)
o Finger dislocations (PIP, DIP joints)
• Radiographic Clues:
o Loss of normal joint congruency.
o Displacement of the joint surfaces.

3. Recognizing Degenerative and Pathological Changes

Chronic musculoskeletal conditions such as osteoarthritis, rheumatoid arthritis, bone tumors,
and infections have distinct radiographic findings that help in diagnosis and disease monitoring.

a. Osteoarthritis (OA)

• Joint Space Narrowing – Due to cartilage degradation.
• Osteophyte Formation – Bone spurs at joint margins.
• Subchondral Sclerosis – Increased bone density beneath the joint surface.
• Subchondral Cysts – Fluid-filled pockets in bone due to cartilage wear.