Merchant view

What is the value of the Merchant view of the knee?

The Merchant view x-ray is also commonly referred to as the skyline view or the sunrise view. It is a highly valuable view, but the need for the special cassette means that it is often omitted in routine knee X-rays.

Its 45 degree angle gives information about -

• how congruent the back of the patella is with the underlying groove, and whether there is trochlear dysplasia
• whether there is any patellar tilt
• whether or not the patella is abnormally displaced to one side, ie the TT-TG distance

Back to top

How does a Merchant view compare to a weight-bearing X-ray?

In the Merchant view the patient lies at rest and any distortion of the anatomy that might be contributed from bearing weight is not appreciated.

So evaluation of any closure of the joint space from osteoarthritis or meniscal degeneration would need a weight-bearing view, such as the Rosenberg view.

Back to top

Can the TT-TG distance be measured on a Merchant view?

Usually a CT or MRI scan is ordered to measure the TT-TG distance, or how out of alignment the patellar tendon is, but in a large number of cases a Merchant view will allow an easier and more affordable way of making this measurement.

Back to top

Other relevant links on KNEEguru

A-Z Keywords -

• Sulcus angle, Patellar alignment, Trochlear dysplasia, Lateral trochlear inclination angle, Excessive lateral pressure syndrome, Patellar tilt test, TT-TG distance, Rosenberg view, Joint space narrowing, TT-TG distance, Tibial tuberosity, Trochlea, Patellar alignment, Patellar tilt

Courses by experts -

• Dr Ronald Grelsamer - Imaging and X-rays for patellofemoral pain

Papers by experts -

• Dr Ronald Grelsamer - X-ray Imaging for patellar malalignment

Back to top