Dunn 45 view: Definition, Uses, and Clinical Overview

Dunn 45 view Introduction (What it is)

Dunn 45 view is a specialized X-ray view of the hip.
It uses a specific leg and hip position to better show the femoral head–neck junction.
It is commonly used in orthopedics and sports medicine when evaluating hip pain.
It is often discussed in the context of femoroacetabular impingement (FAI) and related hip conditions.

Why Dunn 45 view used (Purpose / benefits)

Standard hip and pelvis X-rays (such as an AP pelvis view) do not always show the front and side contour of the femoral head and neck clearly. The Dunn 45 view is designed to improve visualization of the anterosuperior (front-upper) portion of the femoral head–neck junction, which is a frequent site of bony shape differences associated with pain and limited motion.

A common clinical reason to order this view is to look for cam morphology, a bony prominence or loss of the normal “waist” at the femoral head–neck junction. Cam morphology can contribute to femoroacetabular impingement (FAI), a condition where abnormal contact between the femur and acetabulum (hip socket) may irritate joint structures during motion—especially hip flexion and rotation. The Dunn 45 view can also support measurement-based assessments (for example, angles used to describe head–neck shape) when clinicians are documenting hip morphology.

In practical terms, the Dunn 45 view helps clinicians:

• Detect or characterize hip shape features that may not be obvious on other X-ray views.
• Correlate imaging findings with symptoms and physical exam findings.
• Establish a baseline for monitoring over time or for preoperative planning in selected cases.
• Standardize evaluation across visits by using a reproducible radiographic position (though exact positioning can vary by facility and clinician preference).

Indications (When orthopedic clinicians use it)

Orthopedic clinicians may request a Dunn 45 view in scenarios such as:

• Hip or groin pain with concern for femoroacetabular impingement (FAI)
• Suspected or known cam morphology at the femoral head–neck junction
• Reduced hip range of motion (often flexion and internal rotation) with pain during provocative testing
• Preoperative or postoperative imaging around hip arthroscopy (varies by clinician and case)
• Evaluation of hip symptoms in athletes or highly active individuals where bony morphology is part of the differential diagnosis
• Follow-up assessment of hip shape after prior hip conditions that can alter proximal femur anatomy (varies by clinician and case)
• Workup of hip pain where multiple views are needed to complement an AP pelvis and lateral projections

Contraindications / when it’s NOT ideal

The Dunn 45 view is an imaging position rather than a treatment, so “contraindications” typically relate to patient safety, comfort, and the ability to achieve the position without worsening symptoms or violating precautions.

Situations where it may be less suitable, deferred, or replaced by another approach include:

• Inability to flex or position the hip due to severe pain, spasm, or stiffness
• Acute trauma where fracture or dislocation is suspected and positioning could be unsafe (imaging approach varies by clinician and case)
• Early postoperative restrictions where the required positioning is not allowed (varies by surgeon protocol)
• Patients who cannot cooperate with positioning due to cognitive, neurologic, or mobility limitations (varies by case)
• Pregnancy or situations requiring strict radiation minimization, where alternative imaging or deferral may be considered (varies by clinician and case)
• When soft-tissue evaluation is the primary goal (for example, suspected labral tear), where MRI or MR arthrography may be more informative than X-ray

How it works (Mechanism / physiology)

The Dunn 45 view works through radiographic projection and positioning, not through a biologic mechanism. It changes how the X-ray beam passes through the hip by placing the hip in a specific amount of flexion (commonly described as 45 degrees) so that certain bone contours are less overlapped and easier to see.

Relevant hip anatomy it highlights

Key structures involved include:

• Femoral head: the “ball” of the hip joint
• Femoral neck: the narrowed region connecting the head to the shaft
• Head–neck junction: the transition zone where cam morphology may be present
• Acetabulum: the hip socket, which can also have shape variants (though the Dunn 45 view is often discussed for the femoral side)
• Articular cartilage and labrum: important pain-generating and stabilizing tissues, but not directly visible on plain X-ray

What the view is designed to show

By altering hip position, the Dunn 45 view better displays the anterosuperior head–neck contour, a frequent location for bony prominence that may contribute to impingement-type symptoms. Clinicians may use the image to describe morphology and, in some practices, to support measurements used in hip preservation assessment (measurement choice and reliability vary by clinician, technique, and imaging quality).

Onset, duration, and reversibility (as applicable)

Because the Dunn 45 view is a diagnostic image:

• Onset: the “effect” is immediate—visibility is determined at the time the X-ray is taken.
• Duration: the image provides a record of bone appearance at that time.
• Reversibility: the view itself does not change anatomy; it only documents it.

Dunn 45 view Procedure overview (How it’s applied)

Dunn 45 view is not a treatment procedure. It is a specific way to obtain a hip X-ray. Workflows vary by clinic and radiology department, but a general sequence looks like this:

1. Evaluation/exam
   A clinician evaluates symptoms, hip motion, and exam findings, then decides whether additional hip views are needed beyond standard pelvis/hip X-rays.

2. Preparation
   You may be asked to change into a gown and remove items that could interfere with the image (such as metal objects near the pelvis). A technologist typically confirms which side is symptomatic and explains the positioning steps.

3. Intervention/testing (image acquisition)
   The technologist positions the patient and the symptomatic leg in the Dunn 45 view configuration. The goal is to reproducibly align the hip so the femoral head–neck junction is well seen. Exact positioning details can differ by department protocol.

4. Immediate checks
   The technologist checks image quality (positioning, exposure, and whether the target anatomy is visible). A repeat image may be needed if the view is not diagnostic.

5. Follow-up
   A radiologist and/or the ordering clinician interprets the images along with symptoms and exam findings. Next steps depend on the broader clinical picture and may include additional imaging, conservative care, or referral (varies by clinician and case).

Types / variations

“Dunn view” is sometimes used as an umbrella term for related lateral hip projections. Common variations include:

• Dunn 45 view
  Typically described as a hip flexion position around 45 degrees, intended to show the anterosuperior head–neck junction.

• Dunn 90 view
  A deeper flexion variation that may emphasize different aspects of the femoral head–neck contour. Use depends on clinician preference and patient tolerance.

• Modified Dunn views
  Many institutions use protocol-specific “modified” versions to improve reproducibility, patient comfort, or visualization. The name used on a radiology report may vary even when the clinical intent is similar.

• Other lateral hip views used for comparison

• Cross-table lateral view (often used in trauma or postoperative settings)
• Frog-leg lateral view (commonly used for pediatric hip evaluation and general hip screening, though it may be limited or avoided in some acute settings)

Different views are often complementary. Clinicians commonly interpret the Dunn 45 view alongside an AP pelvis view and other projections to build a more complete picture of hip morphology.

Pros and cons

Pros:

• Improves visualization of the femoral head–neck junction compared with some standard views
• Commonly used in workups for femoroacetabular impingement (FAI) and cam morphology
• Relatively quick to obtain in most radiology departments
• Widely available and typically does not require contrast material
• Can support baseline documentation and side-to-side comparison when positioning is consistent
• Helps clinicians correlate bony morphology with exam findings in a structured way

Cons:

• Requires hip positioning that may be uncomfortable or not feasible for some patients
• Plain X-ray cannot directly show labral tears, cartilage injury, or many soft-tissue causes of pain
• Image quality and measurement reliability can vary with patient anatomy, technologist technique, and protocol
• Uses ionizing radiation (dose varies by technique and equipment)
• May not answer the full clinical question, leading to additional imaging (for example, MRI or CT)
• Findings such as cam morphology can be present even in some people without symptoms, so clinical correlation is essential

Aftercare & longevity

There is typically minimal “aftercare” after a Dunn 45 view because it is a diagnostic X-ray. Most people can resume normal activities immediately, unless they were already under activity restrictions for their underlying condition.

What affects the usefulness and “longevity” of the result tends to be practical rather than biological:

• Condition stage and symptom pattern: Imaging is one part of the overall assessment, and its relevance depends on how well it matches symptoms and exam findings.
• Positioning consistency: Reproducible positioning improves the value of comparisons across time, but consistency varies by facility and patient comfort.
• Follow-up plan: Some clinicians use the image as a baseline for monitoring, while others use it mainly for initial decision-making (varies by clinician and case).
• Comorbidities and anatomy: Coexisting hip arthritis, prior surgery, or structural differences can influence interpretation.
• Need for additional imaging: If symptoms suggest soft-tissue injury or complex bony anatomy, clinicians may add MRI or CT for more detail (varies by clinician and case).

Alternatives / comparisons

The Dunn 45 view is one tool among several for evaluating hip pain and hip morphology. Alternatives and complementary options include:

• Standard X-ray views (AP pelvis, AP hip)
  Often the starting point. They provide a broad overview (joint space, alignment, arthritis patterns) but may not highlight the anterosuperior head–neck junction as well as Dunn 45 view.

• Other lateral X-ray projections (cross-table lateral, frog-leg lateral)
  These can show the proximal femur from different angles. Choice depends on the clinical question (trauma vs impingement vs general screening) and patient tolerance.

• False-profile view (for acetabular coverage)
  Sometimes used when evaluating the socket side of the hip, including anterior coverage. It answers a different question than the typical femoral emphasis of Dunn 45 view.

• MRI (or MR arthrography)
  Better suited for labrum, cartilage, tendon, and other soft-tissue evaluation. It can complement X-rays when symptoms suggest internal derangement. Whether contrast is used varies by clinician and case.

• CT scan
  Can provide detailed bone anatomy and 3D assessment, which may be helpful for surgical planning in selected cases. It involves more radiation than plain X-ray, so use is individualized.

• Ultrasound
  Useful for some soft-tissue and guided-injection applications, but it does not provide the same bony contour assessment as Dunn 45 view.

• Observation/monitoring and clinical follow-up
  In some situations, clinicians may monitor symptoms and function first, using imaging selectively based on persistence, severity, and exam findings (varies by clinician and case).

Dunn 45 view Common questions (FAQ)

Q: Is a Dunn 45 view the same as a regular hip X-ray?
A Dunn 45 view is a type of hip X-ray, but it uses a specific position to highlight the femoral head–neck junction. It is often ordered in addition to standard pelvis and hip views, not as a complete replacement.

Q: What conditions can a Dunn 45 view help evaluate?
It is commonly used when clinicians are evaluating femoroacetabular impingement (FAI) and possible cam morphology. It can also be part of a broader hip pain workup where multiple X-ray angles are needed. Interpretation depends on symptoms and exam findings.

Q: Does the Dunn 45 view show labral tears or cartilage damage?
Not directly. Plain X-rays primarily show bones, not the labrum or cartilage. If soft-tissue injury is a key concern, MRI-based imaging may be considered (varies by clinician and case).

Q: Is the Dunn 45 view painful?
Many people feel only mild discomfort, but the required hip positioning can be uncomfortable if the hip is inflamed or stiff. If pain limits positioning, the technologist may adjust or the clinician may choose a different view (varies by case).

Q: How long does the test take, and do I need special preparation?
The imaging itself is typically quick, often just a few minutes once positioned. Preparation is usually limited to removing items that interfere with imaging and following the technologist’s positioning instructions.

Q: How much does a Dunn 45 view cost?
Costs vary widely by region, facility type, insurance coverage, and whether it is billed as part of a larger hip X-ray series. If cost is a concern, clinics and imaging centers can often provide a general estimate before the exam.

Q: Is a Dunn 45 view safe? What about radiation?
It uses ionizing radiation, like other X-rays. Facilities aim to use appropriate, minimized doses for diagnostic quality images, but the exact dose varies by equipment and technique. Clinicians weigh the expected diagnostic value against radiation exposure when ordering imaging.

Q: Can I drive or go back to work afterward?
Most people can return to normal activities right away because it is only an X-ray. Any restrictions usually relate to the underlying hip problem, not the imaging itself.

Q: How long do the results “last”? Will I need repeat imaging?
The image documents your hip’s bony appearance at a point in time. Whether repeat imaging is needed depends on symptom changes, treatment decisions, and clinician preference for follow-up comparisons (varies by clinician and case).

Q: What if I can’t get into the Dunn 45 position?
If positioning is not possible due to pain, limited motion, or precautions, clinicians may use alternative X-ray views or different imaging modalities. The best substitute depends on the clinical question and safety considerations.

Q: If the X-ray shows cam morphology, does that mean it’s definitely the cause of my pain?
Not necessarily. Some bony shape differences can be present even in people without symptoms, and hip pain can have multiple causes. Clinicians typically interpret the Dunn 45 view together with your history, physical exam, and sometimes additional imaging.