Free Hip CT Viewer for Fractures, FAI, and Pelvic Ring Injuries

Getting From Disc To Report

Why A Hip CT Gets Ordered Instead Of An MRI

A fall or high-energy crash is the usual reason a pelvis CT gets ordered at all: the pelvic ring is curved and three-dimensional, and a plain film flattens exactly the detail a surgeon needs. CT maps an acetabular fracture onto the Judet-Letournel columns, telling an anterior column pattern apart from a posterior wall fragment or a transverse fracture running through both columns, because thin axial slices trace fracture lines through curved bone in a way no flat radiograph can. The same reasoning carries over to femoral neck fractures, where displacement and comminution decide between fixing the head and replacing it, and to suspected pelvic ring injuries, where CT settles whether the sacroiliac joint or pubic symphysis has widened enough to call the ring unstable.

CT is also the default check for femoroacetabular impingement and dysplasia. It measures the alpha angle to flag a cam lesion, checks the acetabular rim for a pincer overhang, and reports acetabular version and coverage in a way a plain radiograph cannot capture consistently. When a hip has advanced osteoarthritis, CT shows joint space narrowing alongside subchondral cysts and sclerosis, and when avascular necrosis is suspected, CT can reveal subtle subchondral collapse of the femoral head before it is visible on X-ray. Before a hip replacement or revision surgery, CT-based planning captures bone stock, version, and prior hardware position in a way a standard radiograph cannot, which is why many pre-operative protocols now call for a dedicated pelvis CT.

What A Hip CT Dataset Actually Contains

A pelvis CT comes off the scanner as one helical run of sub-millimeter axial slices covering both hips, and the raw data gets reconstructed twice: a sharp bone kernel that keeps the acetabular columns and femoral neck crisp, and a softer kernel that tones down the edge noise the bone kernel would otherwise leave in the surrounding muscle and fat. Isotropic voxels mean the coronal and sagittal planes built from that one pass hold full resolution, and for a comminuted acetabular fracture or pre-operative templating, the same data spins up as a 3D pelvis render that shows fragment displacement from angles a flat slice simply cannot offer.

What The Viewer Puts In Your Hands

Making Sense Of The Report Wording

Hip CT reports lean on a handful of recurring phrases. “Alpha angle” is reported in degrees and describes how far the femoral head departs from a perfect sphere where it meets the neck; a wider angle points toward a cam lesion. “Rim overhang” or “acetabular coverage” describes how much the socket extends over the femoral head, which factors into whether the shape is read as pincer-type impingement or dysplastic under-coverage. “Subchondral cysts” and “sclerosis” are the bone changes that accompany advancing osteoarthritis, usually paired with a joint space measurement in millimeters. “Subchondral collapse” on a femoral head points toward avascular necrosis that has progressed past the earliest, reversible stage. A post-replacement report covers “component position”, checking the cup or stem against where it was implanted and flagging any lucent line that might mean it has started to loosen.

Where CT Stops And MRI Takes Over

Where CT wins outright is cortical bone: fracture lines through the acetabular columns, how well the pelvic ring lines up, hardware position, and healing all read clearly off a slice. What it cannot do is show the labrum, articular cartilage, or the earliest stage of avascular necrosis with any confidence — those stay an unremarkable gray until you switch to MRI's contrast-weighted sequences. A labral tear or an early osteonecrosis lesion routinely looks like nothing at all on a CT slice even though it is already symptomatic. That gap is why an acetabular fracture gets worked up with CT for the bone first, and an MRI gets added when a labral tear or early avascular necrosis still needs ruling in or out.

Supported Hip CT Formats

Frequently Asked Questions

3D Rendering For Acetabular And Revision Planning

A pelvis series is almost always acquired as a genuine volumetric scan, which is what lets it reformat into MPR and 3D without losing detail along the way. Showing a surgeon how the acetabular columns have separated, how femoral version compares side to side, or where an implant sits is simply faster on a rotating pelvis render than on a stack of flat slices — though how sharp that render looks is still set by the slice thickness, spacing, and kernel the original scan used.

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