How do surgeons decide if I need an osteotomy? The long-leg X-ray explained

Why a normal knee X-ray is not enough

A standard knee X-ray shows the joint space and signs of arthritis, but only a small part of the leg. To plan an osteotomy, the surgeon needs to see the whole limb from hip to ankle while you stand, because alignment is a property of the entire leg under load. Lying-down images can hide how much the knee collapses into a bow when you put weight on it.

What the long-leg X-ray measures

On a single image, a line is drawn from the centre of the hip to the centre of the ankle. This is the weight-bearing line, or mechanical axis. In a bow-legged knee it passes through the inner compartment.

• The angle of the upper tibia and lower femur, showing where the deformity comes from
• How far the weight-bearing line sits from the centre of the knee
• The size of the correction needed to move the line to the planned point
• Whether the deformity is in the shin bone, the thigh bone or both

These measurements, increasingly done with planning software, determine the size of the wedge.

Other tests that help

Examination checks your range of movement, ligament stability, where the pain is and how you walk. An MRI scan shows the state of the cartilage in each compartment, the meniscus, including root tears, and the ligaments, all of which affect whether an osteotomy is likely to help. Sometimes a CT scan or stress X-rays are added. Blood tests, including vitamin D, are often checked before surgery.

Having your assessment in Doha

If you have already had scans elsewhere in Qatar, bring the images and reports. At Aman Hospital, Dr. Gelber will tell you if any further imaging is needed, explain your alignment on the X-ray and discuss whether an osteotomy, a different procedure or continued non-surgical care is the most sensible option.