High tibial osteotomy (HTO) — saving the young arthritic knee

The mechanical logic

In a varus (bow-legged) knee, the body's weight line passes through the inner compartment, wearing it down while the outer compartment stays healthy. A high tibial osteotomy makes a controlled, precisely planned cut in the upper shin bone and adjusts the leg's alignment by calculated degrees, shifting the weight line to the preserved side. The knee you were born with keeps working — now on its good compartment.

Who it is for

The classic candidate: a patient in their 30s–50s, active or working a physically demanding life, with pain localised to the inner knee, arthritis confined to that compartment on X-ray, reasonable range of motion and stable ligaments. For this patient, replacement is the wrong first operation — an implant in a 45-year-old must survive decades of heavy use and likely faces revision; a preserved natural knee carries no such clock.

Two techniques: open wedge vs closed wedge

There are two established ways to realign the bone, and the right one depends on your anatomy:

• Opening wedge (medial): the bone is cut from the inner side and gently opened to the planned angle, then held with a plate. It is precise, adjustable and does not shorten the leg, but relies on the opened gap healing — sometimes with bone graft.
• Closing wedge (lateral): a small wedge of bone is removed from the outer side and the gap closed, giving a very stable bone-on-bone contact that heals reliably, at the cost of slightly more complex technique and a small change in bone length.

Neither is universally superior — the choice is made on your deformity, bone quality and surgeon assessment, and is discussed with you before surgery.

How it is fixed and recovered

Planning is geometric: standing long-leg X-rays establish the exact correction angle before surgery. The osteotomy is fixed with a robust locking plate that holds the correction rigidly, allowing early movement while the bone heals into its new alignment. Weight-bearing is progressed over the first 4–6 weeks, with return to full activity — including sport in many patients — over roughly 3–6 months.

HTO, partial replacement or total replacement?

Three tools for three situations: HTO for the young, active, correctable knee; partial (unicompartmental) replacement for the older or less active patient with single-compartment disease; total replacement for advanced arthritis across the joint. A practice that performs all three can advise without a hammer's bias for nails — this one does.