Authors

Prof Leo Pinczewski MBBS, FRACS

Dr Keran Sundaraj MBBS, MSc (Trauma), FRACS, FAOA

What is an Osteotomy?

An osteotomy is a surgical procedure where a bone is cut and repositioned to correct alignment. In the lower limb, this is commonly performed on the proximal tibia (upper shin bone, just below the knee) or distal femur (lower thigh bone, just above the knee). The goal is to correct bow-legged (varus) or knock-kneed (valgus) alignment, shifting the body’s weight away from worn or arthritic parts of the knee joint. This joint-preserving procedure helps relieve pain, improve function, and may delay or prevent a total knee replacement in younger or active patients.

Why Is a Knee Osteotomy Performed?

Knee osteotomy is most often recommended for patients with unicompartmental osteoarthritis (arthritis in just one part of the knee), especially when the leg is misaligned. For example, bow-legged patients often wear out the medial (inner) side of the knee. An osteotomy straightens the leg to offload this damaged area, redistributing pressure to the healthier lateral (outer) compartment.

This procedure is particularly effective for younger patients under 55, those who are active, and those with good remaining cartilage in the unaffected compartment. In these cases, osteotomy can delay the need for knee replacement by 10–20 years.

Studies from our clinic show a 91% success rate at 5 years, 80% at 10 years, and 60% at 20 years in well-selected patients. Importantly, having had an osteotomy does not prevent future knee replacement if needed.

Understanding Knee Alignment

In a normally aligned leg, a straight line from the hip to the ankle passes through the center of the knee. In a varus (bow-legged) leg, this line shifts inward, increasing stress on the medial compartment. In valgus (knock-kneed) legs, the line shifts outward, overloading the lateral compartment.

Osteotomy adjusts this alignment:

• For varus (bow-legged): the goal is to realign the leg into mild valgus, relieving medial pressure.

• For valgus (knock-kneed): the goal is to shift the leg toward neutral, offloading the lateral compartment.

A/Prof Sundaraj carefully plans each correction with computer modelling and 3D printed cutting guides to ensure optimal alignment and knee function.

Osteotomy Techniques

There are three main types:

• Closing Wedge: A wedge of bone is removed, and the bone edges are closed together.

• Opening Wedge: The bone is cut and wedged open, with a gap filled using bone graft.

• Dome Osteotomy: A curved cut allows rotation around a central axis without removing bone.

The technique used depends on your anatomy, deformity, and specific surgical goals. Below are more details:

Closing Wedge Osteotomy

A small triangular wedge of bone is removed. For varus correction, this is done on the lateral tibia; for valgus correction, on the medial femur. The remaining bone edges are closed and fixed with a plate and screws.

• Leg becomes slightly shorter (a few millimetres).

• Often requires a fibular osteotomy.

• Reliable healing due to large bone contact area.

• May be more technically challenging for future knee replacement—but manageable with robotic assistance.
  Opening Wedge Osteotomy

Instead of removing bone, a cut is made and gently opened to the desired angle. The wedge-shaped gap is stabilized with a plate and often filled with bone graft or substitute.

• Leg may become slightly longer (a few millimetres).

• No need to cut the fibula.

• Allows precise adjustment during surgery.

• Slightly higher risk of delayed bone healing or non-union.Dome Osteotomy

A curved cut (dome) allows the bone to rotate around its center without removing or adding length.

• Leg length is more closely preserved.

• Useful for complex deformities but technically more challenging.

• Avoids changing joint slope or patella height.

• Less commonly used but valuable in selected cases.