Cam morphology imaging: Definition, Uses, and Clinical Overview

Posted on February 27, 2026 | by drhip

Cam morphology imaging Introduction (What it is)

Cam morphology imaging is the use of medical imaging to evaluate a specific shape change at the top of the thigh bone (femur) near the hip joint.
It helps clinicians see whether the femoral head–neck junction is less round than expected.
It is most commonly used when evaluating femoroacetabular impingement (FAI) and related hip pain.
It can be performed with X-ray, MRI, and CT, depending on the clinical question.

Why Cam morphology imaging used (Purpose / benefits)

Cam morphology refers to a bony prominence or loss of normal “waist” at the femoral head–neck junction. When the hip bends and rotates, this shape can reduce clearance between the femur and the acetabular rim (the socket edge). In some people, that contact is associated with symptoms such as groin pain, reduced hip motion, or mechanical catching, and it may contribute to labral or cartilage injury.

Cam morphology imaging is used to:

Confirm or exclude a structural contributor to hip symptoms. Hip pain can come from many sources (muscle/tendon, spine, hernia, arthritis, stress injury). Imaging helps determine whether cam morphology is present and potentially relevant.
Characterize the bone shape in a standardized way. Measurements (such as the alpha angle or head–neck offset) can describe the femoral contour more consistently than physical exam alone. Exact thresholds and measurement technique can vary by clinician and case.
Assess related hip joint findings. MRI-based studies may evaluate the labrum, cartilage, and bone marrow changes that can coexist with cam morphology.
Support treatment planning. Imaging helps clinicians decide whether care is likely to focus on activity modification, rehabilitation, injections used diagnostically, or—when appropriate—surgical options. This is informational only; treatment decisions are individualized.
Provide a baseline for follow-up. In certain situations, imaging can serve as a reference for later comparisons (for example, after surgery or if symptoms evolve).

Indications (When orthopedic clinicians use it)

Orthopedic and sports medicine clinicians commonly consider Cam morphology imaging in scenarios such as:

Hip or groin pain that is activity-related, especially with squatting, pivoting, running, or skating-type motions
Reduced hip internal rotation or flexion noted on exam, particularly when symptoms are reproduced
Suspected femoroacetabular impingement (FAI), including evaluation for combined cam and pincer features
Clicking, catching, or mechanical symptoms suggesting labral involvement (often evaluated with MRI/MRA)
Preoperative planning or postoperative assessment after hip-preserving surgery (varies by surgeon and case)
Young or middle-aged active patients with persistent symptoms and unclear diagnosis after initial evaluation
Assessment after pediatric/adolescent hip conditions that can alter the head–neck contour (for example, healed slipped capital femoral epiphysis), when clinically relevant
Differentiating hip-joint sources of pain from extra-articular causes when the history and exam are inconclusive

Contraindications / when it’s NOT ideal

Cam morphology imaging is a broad concept rather than a single test, so “not ideal” situations depend on the modality and the clinical goal. Common limitations include:

Routine screening in people without symptoms. Cam morphology can be present without pain, so imaging alone may not explain symptoms or predict future problems.
When symptoms strongly suggest a different diagnosis. For example, infection, fracture, tumor, or severe inflammatory disease often requires a different imaging pathway and urgency.
Advanced hip osteoarthritis as the primary issue. When joint space loss and arthritis dominate the picture, cam morphology measurements may be less clinically useful than arthritis-focused assessment; approach varies by clinician and case.
MRI limitations. MRI may not be suitable for some patients with certain implanted devices or retained metal fragments; compatibility depends on the device and manufacturer.
CT radiation considerations. CT uses ionizing radiation, so clinicians typically weigh risks and benefits, especially in pregnancy or when multiple prior CT studies exist.
Arthrogram/contrast considerations (for MRA or CT arthrogram). Contrast injection may not be ideal with contrast allergy concerns, active infection risk at the injection site, or other clinician-identified factors.
Positioning intolerance. Severe pain, limited motion, or inability to lie flat can reduce image quality or feasibility; alternative positioning or modalities may be chosen.

How it works (Mechanism / physiology)

Cam morphology imaging works by visualizing the shape of the femoral head–neck junction and its relationship to the acetabulum (hip socket). The underlying principle is straightforward: imaging captures anatomy that may be difficult to appreciate on exam alone, and it allows clinicians to describe that anatomy using reproducible landmarks and measurements.

Key anatomic structures involved include:

Femoral head and femoral neck: Normally, the head is spherical and transitions into the neck with a slight narrowing (“offset”). Cam morphology describes a reduced offset or extra bone at this junction.
Acetabulum (socket) and acetabular rim: Contact between the cam region and rim during hip motion is one proposed mechanism for impingement-type symptoms.
Labrum: A fibrocartilage ring that deepens the socket. Labral injury can coexist with cam morphology and is often evaluated with MRI/MRA.
Articular cartilage: The smooth joint lining on both femoral head and acetabulum. Cartilage wear patterns may be assessed on MRI, though sensitivity varies by technique and severity.
Capsule and surrounding tissues: Not the primary target for “cam” measurement, but sometimes evaluated for associated findings.

Common imaging-derived descriptors include:

Alpha angle: A measurement intended to quantify loss of femoral head sphericity. Measurement technique and the clinical threshold considered “abnormal” can vary by clinician, view, and patient factors.
Head–neck offset and offset ratio: Metrics that describe how distinct the head is from the neck.
Location and extent of the prominence: Cam morphology can be more anterior, anterosuperior, or distributed; certain views highlight certain regions.

Because Cam morphology imaging is diagnostic, “onset” and “duration” do not apply in the same way as a treatment. Imaging provides a snapshot of anatomy at a point in time. The morphology itself may change slowly during growth and is altered directly only by surgical reshaping, when performed.

Cam morphology imaging Procedure overview (How it’s applied)

Cam morphology imaging is typically used as part of a stepwise diagnostic workflow. The exact sequence varies by clinician, symptoms, and local protocols.

Evaluation / exam – History (pain location, triggers, sports demands, prior injuries) – Physical exam (range of motion, impingement-type maneuvers, gait, strength) – Consideration of non-hip sources (lumbar spine, abdominal wall, tendon disorders)
Preparation – Selection of the imaging modality (often starting with X-rays) – Screening for MRI/contrast issues if advanced imaging is planned – Positioning instructions (hip position matters because it affects how the head–neck contour is displayed)
Intervention / testing (image acquisition) – X-ray: Common first-line views may include an AP pelvis and a lateral view designed to show the head–neck junction (specific view selection varies). – MRI or MRA: MRI evaluates soft tissues and bone marrow; MRA includes intra-articular contrast to better outline the labrum and cartilage surfaces in some settings. – CT (often 3D): CT can provide detailed bone morphology and may be used for complex morphology, preoperative planning, or when MRI is limited.
Immediate checks – Technologists confirm adequate positioning and image quality – If an arthrogram is performed, clinicians may monitor briefly for immediate reactions
Follow-up – A radiology report describes findings and may include measurements – The treating clinician correlates imaging with symptoms and exam findings, since cam morphology can exist without symptoms

Types / variations

Cam morphology imaging is not one single study. It is a category of imaging approaches used to evaluate femoral head–neck shape and related hip findings.

Common types include:

Plain radiographs (X-rays)
Often the starting point for assessing hip structure
Specific lateral views can better show the anterosuperior head–neck junction, where cam features are commonly assessed
May be used to estimate alpha angle and assess other bony features (pelvic tilt, acetabular coverage, arthritis markers)
MRI (non-contrast)
Evaluates cam morphology and adjacent bone marrow signals
Assesses soft tissues: labrum, cartilage surfaces (to a degree), tendons, and surrounding structures
Useful when symptoms suggest intra-articular pathology beyond bone shape
MR arthrography (MRA)
MRI performed after injecting contrast into the hip joint
Often used to improve visualization of labral tears or subtle intra-articular abnormalities (use varies by clinician and center)
CT and 3D CT
High-resolution bone detail and the ability to reconstruct 3D models
Sometimes used for surgical planning, complex bony anatomy, or when precise localization/extent matters
Involves ionizing radiation
CT arthrography
Combines joint contrast with CT imaging in select situations (varies by case)
Dynamic assessment and modeling (specialized)
Some centers use software-based simulations to estimate impingement positions from CT/MRI-based 3D models
Availability and clinical use vary by clinician and case
Ultrasound (limited for cam morphology)
Not typically used to measure cam morphology because bone contour assessment is limited compared with X-ray/CT
May be used for evaluation of tendons or for guided injections rather than morphology measurement

Pros and cons

Pros:

Clarifies whether a bony shape variant consistent with cam morphology is present
Helps localize the region of prominence and estimate severity with measurements (methods vary)
X-rays are widely available and relatively quick to obtain
MRI/MRA can evaluate associated labral and cartilage-related findings without radiation
CT can provide detailed bone definition and 3D visualization when needed
Supports shared decision-making by linking anatomy with symptoms and exam findings (when correlated carefully)

Cons:

Cam morphology can be present in people without pain, so imaging alone may not explain symptoms
Measurements (like alpha angle) can vary by imaging view, positioning, and reader technique
MRI can be limited by motion, claustrophobia, or device compatibility concerns (varies by device and manufacturer)
CT provides radiation exposure, which clinicians try to minimize when possible
Arthrogram-based studies add invasiveness (needle placement) and may cause temporary soreness
Imaging quality and interpretation can vary across facilities and protocols

Aftercare & longevity

Because Cam morphology imaging is diagnostic, “aftercare” is mostly about what happens after the images are obtained and how results are used over time.

Factors that influence how useful and “long-lasting” the results are include:

Correlation with symptoms and exam. The clinical value is highest when imaging findings match the person’s pain pattern, motion limits, and exam findings.
Stage of joint changes. Early or subtle cartilage/labral changes can be harder to detect than advanced injury. The ability of imaging to characterize cartilage varies by modality and technique.
Modality choice and technical quality. Positioning and selected views strongly affect cam visualization on X-ray; MRI field strength, sequences, and motion also affect detail.
Changes over time. Bony morphology generally does not change quickly in adults unless surgically altered. Symptoms, inflammation, and soft-tissue findings may change and sometimes prompt repeat imaging.
Follow-up plan. Some clinicians rely on initial imaging plus clinical follow-up, while others may repeat imaging only if symptoms change or if pre/postoperative comparison is needed; this varies by clinician and case.
Comorbidities and competing diagnoses. Spine disorders, tendon pathology, and arthritis can influence the interpretation of “what matters” on hip imaging.

Alternatives / comparisons

Cam morphology imaging is part of a broader diagnostic approach to hip pain and suspected FAI. Alternatives and comparisons are often about which imaging modality to use and whether imaging is needed right away.

Clinical evaluation and observation/monitoring
A careful history and physical exam can sometimes identify likely causes without immediate advanced imaging
Monitoring may be considered when symptoms are mild or improving, but decisions vary by clinician and case
X-ray vs MRI vs CT
X-ray: Common first step to assess bone shape and arthritis markers; limited for labrum and cartilage.
MRI: Adds soft-tissue evaluation and can identify other causes of pain (stress injury, tendon problems) without radiation.
CT/3D CT: Strong for detailed bone morphology and 3D planning; uses radiation and is typically reserved for specific questions.
MRI vs MRA
MRI: Noninvasive (no joint injection) and widely used.
MRA: May improve visualization of the labrum and subtle intra-articular changes in some settings, but adds an injection step; practice patterns vary.
Imaging vs diagnostic injection (not an imaging replacement, but a comparator tool)
A clinician may use an image-guided intra-articular anesthetic injection to help determine whether pain is coming from inside the hip joint; this does not measure cam morphology but can complement imaging.
Imaging vs surgical findings
Arthroscopy can directly visualize labrum and cartilage, but it is an operative procedure rather than a diagnostic imaging test. Imaging is typically used first to inform whether surgery is even being considered.

Cam morphology imaging Common questions (FAQ)

Q: Is Cam morphology imaging the same as diagnosing femoroacetabular impingement (FAI)?
Cam morphology imaging identifies a bone shape pattern at the femoral head–neck junction. FAI is a clinical diagnosis that combines symptoms, exam findings, and imaging. A person can have cam morphology on imaging without having symptomatic FAI.

Q: Will the imaging test hurt?
Standard X-rays and MRI scans are usually not painful, though positioning can be uncomfortable if the hip is sore. Arthrogram-based studies (MRA or CT arthrogram) involve a needle injection into the joint and may cause temporary discomfort. Experiences vary by person and technique.

Q: How long do the results “last”?
The images reflect the hip anatomy at the time of the scan. In adults, the bony shape generally remains similar over time unless changed surgically, but symptoms and soft-tissue findings can evolve. Repeat imaging is typically considered only when the clinical situation changes or for specific planning needs.

Q: Is Cam morphology imaging safe?
Safety depends on the modality. X-rays and CT use ionizing radiation, while MRI does not. Contrast-based arthrograms add an injection step and have additional considerations; clinicians weigh benefits and risks for each individual.

Q: Does an abnormal alpha angle mean I need treatment?
Not necessarily. Measurements like the alpha angle help describe morphology, but they do not determine treatment by themselves. Clinicians interpret these measurements in context because thresholds and clinical significance vary by clinician and case.

Q: How much does Cam morphology imaging cost?
Costs vary widely by region, facility type, insurance coverage, and whether advanced imaging or an arthrogram is used. In general, X-rays tend to cost less than MRI or CT, and arthrogram studies may add costs due to the injection component. For exact pricing, patients typically need facility-specific estimates.

Q: Can I drive or work afterward?
After routine X-rays or MRI, many people can return to usual activities right away, depending on discomfort and facility instructions. After an arthrogram injection, some clinicians recommend limited activity for the rest of the day, and driving may depend on soreness or any medications used. Instructions vary by clinician and case.

Q: Do I need to avoid weight-bearing after the scan?
Imaging itself usually does not change weight-bearing status. If an arthrogram is performed, there may be short-term soreness, but formal restrictions are not universal. Any limits are determined by the underlying condition and the clinician’s protocol.

Q: What if I’m pregnant or might be pregnant?
Clinicians typically try to avoid or minimize ionizing radiation (X-ray/CT) during pregnancy unless medically necessary. MRI may be considered in some circumstances because it does not use radiation, but contrast use and timing considerations vary. Patients should inform the imaging team and ordering clinician about pregnancy status.

Q: What’s the difference between cam and pincer findings on imaging?
Cam refers to the femoral head–neck shape, while pincer features relate more to the acetabulum (socket coverage or rim anatomy). Some people have a combination of both patterns. Imaging helps describe each component so clinicians can interpret the overall hip mechanics alongside symptoms and exam findings.