The short answer: yes, for the right patient

For a carefully selected patient, the answer is yes — and the survival figures back this up clearly.

After high tibial osteotomy (HTO), the most studied of these procedures, 95% of patients had not required a total knee replacement at five years, and 79% remained replacement-free at ten years (Primeau et al., 2021). Pooled data across larger populations show a cumulative conversion rate of roughly 6.7% at five years, rising to between 21% and 36% at ten years — a clear majority of well-selected patients keep their native knee through a decade without replacement.

Evidence for distal femoral osteotomy (DFO) is thinner but points in the same direction: 70–90% survivorship at ten to fifteen years, with Ismailidis et al. (2023) finding that only 7% of a prospective DFO cohort ultimately required arthroplasty at around five years, with 71% of patients satisfied at follow-up.

The twenty-year HTO picture is more sobering: survivorship falls to approximately 44%. For many patients, osteotomy represents a long delay rather than a permanent alternative to replacement. Both procedures are classified as joint-preservation surgery — the goal is to maintain the native knee for as long as the biology allows, not to act as a stop-gap once all else has failed.

What osteotomy actually does to a damaged knee

The underlying problem in one-sided knee osteoarthritis is often mechanical before it is degenerative. When the leg's weight-bearing axis — the straight line running from hip to ankle — passes too far inward or outward, load concentrates in a single compartment rather than being shared across the whole joint. In a varus, or bow-legged, knee, that line tracks through the medial (inner) compartment; in a valgus, or knock-kneed, knee, it overloads the lateral (outer) side. That sustained, abnormal pressure accelerates cartilage thinning precisely where the surface is already compromised.

HTO addresses this by cutting and repositioning the upper tibia so the mechanical axis shifts away from the damaged medial compartment, spreading load more evenly toward the intact lateral side. DFO achieves the equivalent correction for valgus knees by reshaping the lower femur to redirect force away from the lateral compartment.

Once load is redistributed, the abnormal stress concentration on the damaged cartilage reduces — and with it, the rate at which that cartilage breaks down. Some clinical evidence suggests remaining cartilage may stabilise rather than continue to deteriorate.

No implant is placed inside the knee during either procedure. The Royal Berkshire NHS Foundation Trust describes both operations as native-bone-preserving, which has a practical consequence that matters greatly to younger patients: the joint's own architecture remains intact. If a total knee replacement does eventually become necessary, it remains technically feasible, and published conversion outcomes remain excellent.

Who this surgery is — and is not — for

Osteotomy is not a universal solution for knee osteoarthritis. Patient selection is arguably the most important determinant of outcome — which is why surgeons apply a fairly precise set of criteria before recommending either procedure.

The qualifying condition is unicompartmental OA with malalignment: osteoarthritis confined to one side of the joint, combined with a measurable deviation in the leg's mechanical axis. The typical candidate is younger than 55–60, active, with a BMI below 30 and stable knee ligaments. These are not arbitrary thresholds. Twenty-year HTO data show that age under 55, BMI under 30, and a better baseline pain score (WOMAC above 45) are independently associated with longer survivorship before conversion to replacement becomes necessary.

Who is unlikely to benefit

Advanced or diffuse OA — where deterioration has spread across more than one compartment — substantially diminishes the case for osteotomy. If the cartilage in the compartment that would receive the redirected load is already damaged, shifting load there creates a second problem rather than solving the first. This is why pre-operative arthroscopy to assess contralateral compartment health is standard practice before committing to either procedure: it is a safeguard, not a formality, and when the opposite compartment cannot support increased load, osteotomy is unlikely to help.

For valgus knees, the Coventry rule — established in 1973 — provides the surgical decision boundary: a valgus deformity greater than 12°, or a joint-line deviation greater than 140° from horizontal, indicates that correction should come at the femur (DFO) rather than the tibia.

Pre-surgical planning also benefits from understanding how the malalignment behaves dynamically under load during movement, not only on static imaging. At MSK Doctors, MAI Motion® markerless gait analysis forms part of the clinical workup for patients being assessed along this pathway.

HTO vs DFO: how the evidence compares

Placing the two procedures side by side reveals a genuine asymmetry — not in the principle behind them, which is the same, but in the volume and rigour of the supporting evidence.

HTO: the better-characterised procedure

HTO has accumulated one of the larger evidence bases of any joint-preservation operation. Multiple Level I and Level II studies, large national registry datasets, and follow-up stretching to twenty years give a clear picture of who does well and when conversion to replacement typically occurs. Pooled data point to a TKR conversion rate of roughly 6.7% at five years, rising to 21–36% at ten years — meaning that a clear majority of appropriately selected patients remain replacement-free at a decade. The twenty-year survivorship figure of approximately 44% reflects the natural ceiling for a procedure performed on a joint that already has established disease, rather than a failure of the technique.

DFO: same rationale, thinner evidence

DFO rests on the same biomechanical logic but has a considerably smaller published evidence base. Most data come from Level IV case series rather than randomised or controlled trials; long-term RCT evidence for DFO does not currently exist. In a prospective cohort reported by Ismailidis et al. (2023), 28 DFOs in 22 patients produced a conversion-to-arthroplasty rate of approximately 7% at a median follow-up of 59 months — superficially similar to the HTO five-year figure, but drawn from a dataset too small to draw firm conclusions. Patient satisfaction was 71% in that cohort.

The complication profile warrants direct attention: in the same series, minor complications occurred in roughly 25% of cases, major complications in 14%, delayed union in 18%, and hardware removal was required in 71% of patients. These are not reasons to dismiss DFO for the right candidate — preserving a 35-year-old's native joint has real long-term value — but they are clinical realities that should be part of any shared decision-making conversation.

The safety net: conversion remains open

Neither procedure forfeits the option of future knee replacement. When osteotomy eventually runs its course, conversion to TKR is technically feasible and well-documented; revision-free outcomes of 86–95% have been reported post-HTO. Prior hardware can add some technical complexity, but it does not close the door. Framing osteotomy this way matters: it is not a high-stakes gamble on a single outcome but a considered first move in what may be a longer care plan — one that preserves the native joint for as long as it serves the patient well.

Combining osteotomy withcartilage repair

Correcting alignment and repairing damaged cartilage are not mutually exclusive steps — and for patients who have both problems, treating only one of them is likely to shorten the life of the treatment. A graft or scaffold placed into a compartment that remains mechanically overloaded faces the same destructive forces that caused the original damage; without the alignment correction, any cartilage repair is working against the joint's own loading pattern.

For this reason, HTO and DFO now function routinely as enabling procedures in specialist cartilage units. Combining osteotomy with autologous chondrocyte implantation (ACI), matrix-induced ACI (MACI), autologous matrix-induced chondrogenesis (AMIC), osteochondral autograft transfer (OATS), or fresh osteochondral allograft (OCA) is well-established practice when malalignment and a focal cartilage lesion coexist. The osteotomy creates the mechanical environment in which the cartilage repair can succeed.

The sequencing of these two interventions depends on the clinical picture. In some cases, both procedures are completed in a single operative session. In others — particularly where the cartilage defect requires a staged biological approach, such as ACI — the osteotomy is performed first and the cartilage work follows once the corrected alignment has been confirmed and the joint has settled. The choice of sequence is made at the planning stage.

Pre-operative arthroscopy remains the recommended checkpoint before committing to the combined approach. Assessing the contralateral compartment directly allows the surgical team to confirm it can bear the redirected load and to plan any cartilage work with a clear picture of what they will find.

What to expect: assessment, recovery, and next steps

Assessment typically begins with standing, weight-bearing X-rays alongside MRI, which together establish the degree of malalignment and confirm which compartment is involved. At MSK Doctors, this is augmented by MAI Motion® — the group's AI-powered markerless motion capture system — which adds objective biomechanical data by measuring how load moves through the joint during normal walking, giving the clinical team a dynamic picture alongside the static imaging.

Surgery is performed under general or regional anaesthetic. A relatively small incision allows the surgeon to make the correction and secure it with plate-and-screw fixation; the technique is broadly similar for both HTO and DFO. Protected weight-bearing typically continues for six to twelve weeks while bone heals; sustained return to sport or demanding physical activity generally takes nine to twelve months. For DFO patients, hardware removal once union is confirmed is a planned follow-on step — routine, and usually day-case — rather than an unplanned complication, though it is worth factoring into the overall timeline from the outset.

The thread running through all the evidence reviewed here is worth stating plainly: osteotomy is not a passive delay strategy. For a well-selected patient — younger, active, with unicompartmental disease and measurable malalignment — it is an active investment in a decade or more of preserved native-joint function, with the option of knee replacement remaining fully intact throughout. That combination of time, function, and open choices is what distinguishes it from accepting either early replacement or the status quo.

To find out whether osteotomy is the right first step for your knee, you can book a consultation at MSK Doctors without a referral at mskdoctors.com.

1. [1] High tibial osteotomy – Wikipedia. https://en.wikipedia.org/?curid=42896695 https://en.wikipedia.org/?curid=42896695