What Is a Distal Femoral Osteotomy, and When Is It Chosen?

What exactly is a distal femoral osteotomy?

A distal femoral osteotomy is a controlled surgical cut made near the lower end of the femur, just above the knee joint. The surgeon removes or adds a small wedge of bone, then fixes the new position with a plate. This changes the angle of the thigh bone so that the weight-bearing line of the leg passes through the centre of the knee rather than overloading the lateral (outer) compartment.

The word "distal" simply means "the end closest to the knee," and "osteotomy" means "bone cut." The procedure preserves your own joint surfaces rather than replacing them. This is why it is often described as joint-preserving knee surgery.

The goal is simple: redistribute load across the knee so that healthy cartilage carries more of the work and damaged cartilage is protected. For many younger adults, this buys valuable years of pain-free activity before a replacement becomes necessary.

How do you know your knee alignment might need correction?

Valgus alignment, commonly called knock knees, is not always obvious. Some people have lived with a mild angle for years before pain develops. The signs below may suggest that the outer compartment of your knee is under excess strain.

These signs do not confirm you need a distal femoral osteotomy. They simply suggest that a proper alignment assessment, ideally standing up, could help identify the structural cause.

What causes valgus knee alignment?

Valgus alignment develops when the weight-bearing line of the leg drifts to the outside of the knee centre. This can happen for several reasons.

Understanding the cause matters because it affects whether the problem sits in the femur, the tibia, or both. When the deformity originates in the femur, a distal femoral osteotomy addresses it at the source. If the tibia is the main contributor, a different procedure, such as knock knee surgery at the tibial level, may be more appropriate. Accurate imaging is the key to making that distinction.

What surgical techniques are used in a distal femoral osteotomy?

Surgeons typically choose between two approaches, depending on the pattern and size of the correction needed.

In both cases, the correction angle is calculated before surgery using precise standing images of the full leg. The surgeon traces the weight-bearing line, measures the current angle, and plans exactly how much correction is needed. This is why high-quality, weight-bearing imaging is so important.

Why does pre-operative planning need standing imaging?

When you lie down for a conventional x-ray or CT scan, gravity stops pulling on your joints. Your muscles relax and the leg may straighten slightly, masking the true valgus angle. A full-leg standing x-ray captures your alignment the way you actually use your legs, under real body weight.

EOS imaging takes this a step further. The scanner captures both legs from hip to ankle in a single upright exposure, with about 90% less radiation than a standard x-ray, around ten times less. Because the image is calibrated, surgeons can take accurate measurements directly from the scan without magnification errors.

At ScanAlign, standing EOS imaging in London, a specialist radiographer positions you naturally in the scanner and produces a detailed report covering your alignment from hip to foot. Your surgeon then uses this to plan the correction angle for a distal femoral osteotomy, or to decide whether a different approach is more suitable.

Who is a good candidate for a distal femoral osteotomy?

A DFO is typically recommended for adults who have valgus malalignment with damage mainly in the lateral compartment, but who still have healthy cartilage on the inner side. It suits people who want to stay active and delay a partial or total knee replacement.

Only your orthopaedic surgeon can decide if a DFO is right for you. What imaging provides is the objective alignment data your surgeon needs to make that decision with confidence. If you would like to book pre-operative alignment imaging, a short free video consultation is the first step.

What does recovery from a distal femoral osteotomy look like?

Recovery varies from person to person and depends on the technique used, the size of the correction, and your general health. In broad terms, most people follow a gradual path back to activity.

• Early weeks. Crutches and limited weight-bearing to protect the healing bone. Physiotherapy begins soon after surgery.
• Middle phase. Gradual return to weight-bearing as x-rays confirm bone healing. Swimming and cycling are often reintroduced before impact sports.
• Longer term. Full activity, including running and sport, may be possible once the bone has fully healed and the muscles have recovered strength.

Your surgical team will give you a personalised timeline. ScanAlign does not perform surgery or manage rehabilitation. Its role is to provide the standing alignment imaging that supports both pre-operative planning and, if your surgeon requests it, follow-up comparison scans.

Frequently asked questions about distal femoral osteotomy