Medial compartment osteoarthritis — the most common form of knee arthritis — develops on the inner side of the knee. One reason it concentrates there is leg alignment: a knee that is naturally varus (bowed outward) directs the majority of body weight through the medial compartment, accelerating the wear of cartilage on that side. High tibial osteotomy (HTO) addresses this problem at its source.

Rather than replacing the worn joint, HTO realigns the tibia so that the load-bearing axis shifts from the medial compartment toward the lateral. The worn cartilage is effectively unloaded. Pain decreases, function improves, and in well-selected patients, joint replacement can be deferred by a decade or more — sometimes indefinitely.

Who Is a Candidate for HTO?

Ideal HTO candidate

  • Age under 60–65 (though age alone is not disqualifying)
  • BMI under 30
  • Isolated medial compartment arthritis — lateral compartment and patellofemoral joint relatively preserved
  • Varus (bowed) leg alignment
  • Good range of motion (flexion to at least 120°, minimal fixed flexion contracture)
  • Stable ligaments (or ligament reconstruction can be done concurrently)
  • Physically active with high functional demands that a knee replacement cannot fully accommodate

HTO is particularly well suited to patients who want to remain physically active — skiers, hikers, cyclists, martial artists, and manual workers — for whom the activity restrictions associated with knee replacement are unacceptable.

The Surgical Technique

The modern standard for HTO is the medial opening wedge technique, performed with a locking plate and, in some cases, bone graft or a substitute to fill the correction gap.

The procedure involves making a cut (osteotomy) in the upper tibia on the medial side, then carefully opening the cut to the degree required to shift the mechanical axis from varus to a slight valgus — typically targeting a mechanical axis passing through 62–66% of the tibial plateau width. The correction is held with a locking plate and screws while the osteotomy heals. The plate is usually removed 12–18 months after surgery once healing is confirmed.

The principle: By slightly over-correcting the alignment to create a mild valgus position, we shift the load-bearing axis away from the damaged medial compartment. The amount of correction is planned precisely on pre-operative weight-bearing radiographs using digital templating.

HTO Combined With Cartilage Restoration

In some patients, HTO is performed at the same time as a cartilage restoration procedure — such as microfracture, OATS, or ACI — to treat a focal defect on the medial femoral condyle or tibial plateau. The realignment created by HTO unloads the repaired cartilage during healing, dramatically improving the biological environment for successful repair. This combination is an increasingly important strategy for young, active patients with early arthritis and focal defects.

What the Evidence Shows

Based on articles retrieved from PubMed, a landmark prospective study by Constantin et al. (2024) followed 100 consecutive patients for 20 years after lateral closing-wedge HTO. Overall survivorship at 20 years was 44% — meaning almost half the patients had never needed a knee replacement two decades later. In the subgroup of favorable candidates (age under 55, BMI under 30, moderate disability at baseline), survivorship was 100% at 5 years and 62% at 20 years. Of those whose HTO had survived, 97% reported satisfaction with surgery. DOI: 10.1177/03635465231217742

62%
HTO survivorship at 20 years in ideal candidates
97%
Patient satisfaction at final follow-up
91
Mean KOOS Pain score in surviving patients

These are results from a technique that is now over 30 years old. Modern opening wedge HTO with contemporary locking plate fixation and careful patient selection produces at least equivalent — and likely superior — outcomes.

HTO vs Knee Replacement: How to Choose

This is the most common question patients bring to consultation. The decision depends on age, activity level, BMI, degree of arthritis, and patient preference.

When HTO is preferred over knee replacement

  • Age under 55–60 with isolated medial arthritis
  • High activity demands — especially sports involving impact, pivoting, or deep flexion
  • Isolated compartment disease (lateral compartment and patellofemoral joint preserved)
  • Patient preference to preserve biological tissue and avoid implant

When knee replacement is preferred

  • Age over 65, or lower activity demands
  • Tricompartmental arthritis (all three compartments involved)
  • BMI over 35
  • Poor bone quality or range of motion
  • Patient preference for predictable pain relief with shorter rehabilitation

HTO and knee replacement are not competing procedures — they are complementary options for different stages of the disease and different patient profiles. Importantly, a well-executed HTO does not compromise a future knee replacement if that becomes necessary.

Recovery Timeline

Typical HTO recovery

  • Week 1–2: Toe-touch weight-bearing, crutches, wound care
  • Week 3–6: Progressive weight-bearing as tolerated
  • Week 6–10: Full weight-bearing, physiotherapy intensifies
  • Month 3–4: Cycling, swimming, light activity
  • Month 6: Return to most recreational activities
  • Month 9–12: Return to impact sports (sport-dependent)
  • Month 12–18: Hardware removal (if planned)

Frequently Asked Questions

Will I definitely still need a knee replacement eventually?

Not necessarily. In the best-case scenario — younger, lighter, less severely arthritic patients — a significant proportion never progress to knee replacement. In others, HTO provides 10–15 years of additional pain-free function before replacement becomes appropriate. Either outcome represents a meaningful improvement over having replacement surgery earlier.

Can HTO be done at the same time as ACL reconstruction?

Yes. In patients with varus malalignment and ACL deficiency, combined HTO and ACL reconstruction can be performed. The realignment reduces the varus stress that contributes to recurrent ACL graft failure in varus knees.

Is HTO covered by Japanese national health insurance?

Yes. HTO is a covered procedure under NHI. Foreign residents enrolled in the Japanese health insurance system pay the standard 30% co-pay.

I live outside Japan. Can I travel for HTO?

Yes. I have experience coordinating care for international patients traveling to Tokyo for surgery. Preoperative imaging and planning can be partially completed remotely, with in-person assessment and surgery performed over a scheduled visit. Follow-up imaging and communication can be managed in collaboration with your local physician.

Medial knee arthritis — not ready for a replacement?

First consultation is free — 30 minutes, in person or by video. Let's look at your imaging together and discuss whether HTO is right for you.

Book a Free Consultation

References

Constantin H, et al. 20-Year Outcomes of High Tibial Osteotomy: Determinants of Survival and Functional Outcome. Am J Sports Med. 2024;52(2):344–351. DOI: 10.1177/03635465231217742

Selley R, et al. Osteochondral Allograft and High Tibial Osteotomy With Patient-Specific Instrumentation. Video J Sports Med. 2023;3(4). DOI: 10.1177/26350254231186435