Orthopaedic Surgery - Musculoskeletal Radiography

Basics

Plain radiography is often the first imaging study obtained when evaluating a musculoskeletal complaint.

Radiographs are useful because they are:

Widely available

Relatively inexpensive

Rapid to obtain

Excellent for evaluating bone alignment, fracture, joint space, and many osseous lesions

The quality of the study and its interpretation depend heavily on the clinical information supplied with the imaging request.

Clinical Information on the Radiograph Request

When ordering musculoskeletal radiographs, the clinician should provide a clear description of:

The location of symptoms

The suspected diagnosis

Mechanism of injury

Relevant examination findings

Previous surgery or known disease

Adequate clinical information helps the radiologist select the correct views and interpret subtle abnormalities more accurately.

Diagnosis

History

For traumatic injuries, the mechanism of injury should be included.

Examples include:

Fall

Direct blow

Twisting injury

Hyperextension

Axial loading

Crush injury

Understanding the mechanism can help identify expected fracture or dislocation patterns.

Physical Examination

Any focal areas of:

Tenderness, swelling, deformity, or limited motion

should be specified.

Precise localization can guide imaging toward the most likely site of pathology.

General Radiographic Principles

Two Orthogonal Views

Most suspected fractures should be assessed with at least two projections obtained approximately 90° to one another.

The classic combination is:

Anteroposterior and lateral views.

A fracture or dislocation that is difficult to appreciate on one projection may be obvious on the perpendicular view.

Trauma Imaging

In substantial extremity trauma, imaging should include the injured segment and consideration of the:

Joint above and joint below the suspected injury.

This is particularly important with long-bone fractures or when associated dislocation may be missed.

The exact extent of imaging should be tailored to the mechanism and examination rather than applied mechanically to every minor injury.

Additional Views

Specialized projections may be required when standard AP and lateral studies do not adequately visualize the region.

Examples include:

Oblique views

Axillary views

Scapular Y views

Patellar or skyline views

Weight-bearing views

Stress views

General Indications by Anatomic Region

Neck Pain

Initial cervical spine radiographs, when clinically indicated, commonly include:

AP and lateral views.

Additional projections or CT may be more appropriate depending on trauma severity and the clinical question.

Routine chest radiography is not required solely because cervical pain is present unless there is another indication.

Neck and Arm Pain

When cervical radiculopathy or another source of referred upper-extremity pain is suspected, imaging may include:

Cervical spine radiographs

and, depending on examination findings,

Shoulder, humerus, forearm, wrist, or hand radiographs.

Imaging should be directed toward the suspected level rather than routinely obtaining every segment.

Shoulder Pain

Nontraumatic Shoulder Pain

Initial radiographs often include:

AP views in appropriate rotation

and

An axillary or scapular Y view.

These help evaluate:

Glenohumeral alignment

Arthritis

Calcification

Acromial morphology

Osseous lesions

Traumatic Shoulder Pain

When the patient cannot move the arm because of pain, useful views include:

AP

and

Scapular Y views.

The Y view is useful because it can often be obtained without substantial shoulder movement and helps assess for dislocation.

Elbow Pain

Standard elbow radiographs generally include:

AP and lateral views.

Oblique views may be added for suspected:

Radial head, coronoid, or other subtle fractures.

Forearm Pain

Forearm imaging should include:

AP and lateral views of the entire radius and ulna, with adequate visualization of both the:

Elbow

and

Wrist.

This is especially important because forearm fractures may be associated with injuries such as:

Monteggia or Galeazzi fracture-dislocations.

Wrist Pain

Standard wrist imaging generally consists of:

PA/AP

Lateral

and often

Oblique views.

Special views may be required for suspected scaphoid or carpal injury.

Hand Pain

Standard hand radiographs commonly include:

PA/AP

Oblique

and

Lateral views.

Wrist imaging should be added when symptoms extend proximally or when the mechanism suggests associated carpal injury.

Low Back Pain

When plain radiographs are clinically indicated, typical views include:

AP and lateral lumbosacral spine radiographs.

An AP pelvis may be useful when:

Hip, sacroiliac, or pelvic pathology is also suspected.

Routine radiography is not necessary for uncomplicated acute low back pain without concerning clinical features.

Thoracic or Middle Back Pain

When indicated, standard thoracic spine radiographs include:

AP and lateral views.

These may identify:

Compression fracture

Deformity

Degenerative change

Destructive lesion

Pelvic Pain

Initial pelvic imaging often begins with:

An AP pelvis radiograph.

Additional hip or lumbosacral views are obtained according to the location of symptoms and suspected diagnosis.

Hip Pain

Typical radiographic evaluation may include:

AP pelvis

and

AP and lateral views of the affected hip.

Lumbosacral imaging may be considered when symptoms could represent referred spinal pain.

Knee Pain

Standard knee imaging commonly includes:

Weight-bearing AP or PA view

Lateral view

Patellofemoral view

Depending on the suspected disorder, additional views may include:

Tunnel, Rosenberg, or long-leg alignment studies.

Weight-bearing views are particularly useful when evaluating osteoarthritis.

Ankle Pain

Typical ankle radiographs include:

AP

Lateral

Mortise views.

Foot radiographs may be added when tenderness or trauma extends into the foot.

Foot Pain

Standard foot imaging usually includes:

AP

Lateral

Oblique views.

Weight-bearing radiographs are especially useful for:

Alignment disorders, midfoot instability, hallux valgus, and flatfoot evaluation.

Ankle views should be added when symptoms extend proximally.

Interpretation Principles

Radiographs should be reviewed systematically.

Alignment

Evaluate:

Overall limb and joint alignment

Joint congruity

Dislocation or subluxation

Bone

Inspect for:

Fracture lines

Cortical disruption

Trabecular abnormalities

Lytic or sclerotic lesions

Periosteal reaction

Joint Space

Assess:

Joint-space width

Symmetry

Articular congruity

Osteophytes

Subchondral sclerosis

Erosions

Soft Tissues

Do not ignore the soft tissues.

Radiographs may reveal:

Swelling

Joint effusion

Calcification

Gas

Foreign bodies

Soft-tissue masses

Comparison Views

Comparison with the opposite extremity may occasionally help in:

Pediatric injuries

Subtle alignment abnormalities

Congenital conditions

Routine bilateral imaging is not necessary for every injury.

Follow-Up

If initial radiographs are normal but significant symptoms persist, management depends on the clinical problem.

Repeating radiographs after a period of time may reveal abnormalities that were initially occult.

Repeat Radiographs

Certain fractures become more visible after:

Callus formation or bone resorption at the fracture margins.

Repeat imaging may therefore be useful after approximately 1–2 weeks for selected occult fractures.

A routine delay of 6–8 weeks is generally not necessary when significant pathology is suspected and more sensitive imaging is available.

Persistent Unexplained Pain

When radiographs remain normal but important symptoms persist, additional imaging should be selected according to the likely diagnosis.

Options include:

MRI

CT

Bone scintigraphy

Bone Scintigraphy

Technetium bone scanning provides a whole-skeleton survey of areas with increased bone turnover.

It may be useful when:

The location of disease is uncertain

Multifocal skeletal disease is suspected

Stress injury, infection, or metastasis is under consideration

Limitations of Bone Scanning

A positive scan is nonspecific and may occur with:

Fracture

Arthritis

Infection

Tumor

Other causes of increased bone remodeling

Some disorders, such as multiple myeloma, may be occult on technetium bone scanning.

Computed Tomography

CT provides excellent visualization of:

Cortical bone

Complex fracture anatomy

Subtle osseous lesions

Joint surfaces

Spinal and pelvic anatomy

It is especially useful when plain radiographs are inconclusive but detailed bony anatomy is required.

Magnetic Resonance Imaging

MRI is often the most sensitive study for detecting occult musculoskeletal pathology.

It is particularly useful for:

Bone marrow disease

Occult fracture

Ligament and tendon injury

Meniscal or labral pathology

Tumor

Infection

Spinal cord and nerve-root disease

Limitations of MRI

MRI has practical limitations including:

Greater cost

Longer acquisition time than radiography or CT

Sensitivity to patient motion

Claustrophobia

Device- or implant-related safety considerations

Modern MRI studies often take substantially less than the historically quoted 40–60 minutes, depending on the region and protocol.

Claustrophobia

Patients with significant claustrophobia may require:

Reassurance

Wide-bore or open MRI

Anxiolytic medication

or, rarely,

Sedation or anesthesia.

MRI Safety

Implanted devices should not automatically be considered absolute contraindications.

MRI safety depends on whether the device is:

MR safe

MR conditional

or

MR unsafe.

Pacemakers and Defibrillators

Many modern cardiac devices are MR conditional and can be scanned under specialized protocols.

The exact device must be identified before MRI.

Orbital Metal

Patients with a history suggesting metallic fragments near the eye require careful screening.

A ferromagnetic intraorbital foreign body can move in the magnetic field and cause serious injury.

Implanted Stimulators

Neurostimulators and other implanted electrical devices require device-specific safety evaluation.

Some can be scanned under defined conditions, whereas others cannot.

Key Principle

Musculoskeletal radiography remains the first-line imaging modality for many orthopaedic conditions, particularly fractures, alignment abnormalities, and arthritis.

The most useful study is obtained when the clinician:

Provides an accurate history and examination findings, requests appropriate orthogonal and special views, and selects advanced imaging only when the clinical question requires it.