The goal of this clinical trial is to verify whether the "dynamic dual-mode alignment optimization + intelligent precision knee-preserving system" (integrating static/kinematic target alignment, CT-based preoperative three-dimensional [3D] planning, 3D-printed guide plates, and intraoperative augmented reality [AR] real-time feedback) achieves a greater relative reduction in peak knee adduction moment (KAM) at 12 months postoperatively, while maintaining or improving knee clinical function and without increasing perioperative or long-term complication rates, compared with traditional knee-preserving strategies. The target population is patients aged 40-70 years with knee osteoarthritis (KOA; Kellgren-Lawrence grade II-III) who require high tibial osteotomy (HTO) for unilateral medial-compartment disease with mild-to-moderate varus deformity and who meet the inclusion and exclusion criteria.

The main questions are:

• Can the dynamic dual-mode alignment + intelligent precision system achieve a greater relative reduction in peak KAM at 12 months postoperatively than traditional knee-preserving strategies?
• Can this system improve static alignment accuracy, dynamic load parameters (e.g., KAM impulse and varus thrust), and patient-reported outcome (PRO) scores without increasing complication rates?
• Can 3D-printed patient-specific instrumentation (PSI) guide plates and real-time AR feedback reduce intraoperative radiation exposure and shorten operative time compared with traditional methods?

Researchers will compare:

Kinematic alignment (KA), traditional mechanical alignment (MA), and dynamic dual-mode alignment (DA) to evaluate the relative performance of alignment strategies;

3D-printed PSI-guided HTO versus traditional fluoroscopy-guided HTO to assess the efficacy of PSI; and

AR-assisted intraoperative adjustment versus traditional fluoroscopy-based adjustment to evaluate the precision of AR navigation.

Participants will:

• Complete preoperative assessments, including laboratory tests (complete blood count, biochemistry, coagulation), imaging (full-length, weight-bearing lower-limb radiographs; knee CT and/or MRI as indicated), 3D gait analysis (to measure KAM, KAM impulse, and varus thrust), and PRO assessments (KOOS, WOMAC, and Lysholm scores)
• Receive assigned surgical interventions: the DA group will undergo HTO guided by dual-mode alignment plus 3D-printed PSI and intraoperative AR feedback; the MA and KA groups will undergo HTO based on traditional or kinematic alignment, respectively; the traditional HTO group will undergo surgery relying on intraoperative fluoroscopy and surgeon experience.
• Attend follow-up visits at 6 weeks, 3 months, 6 months, and 12 months postoperatively, including imaging to assess alignment accuracy and bone healing, gait analysis, PRO assessments, and complication monitoring.
• Record medication use and rehabilitation compliance throughout the study period.

Inclusion Criteria:

1. Age between 40 and 70 years;
2. Unilateral medial compartment knee osteoarthritis (mild to moderate pain);
3. Mild to moderate varus deformity (5°-15°);
4. Coronal MRI showing medial meniscus extrusion (MME) >3 mm and flexion contracture <10°;
5. Intact lateral meniscus and articular cartilage;

Exclusion Criteria:

1. Patients with concomitant inflammatory arthritis (e.g., rheumatoid arthritis) or systemic inflammatory diseases;
2. Patients with severe varus deformity (>10°) or flexion contracture >10°;
3. Patients with lateral meniscus pathology (tear, discoid meniscus) or knee joint instability;
4. Patients with a history of major knee trauma, infection, or prior knee surgery;
5. Patients with severe patellofemoral osteoarthritis;
6. Patients with advanced medial compartment osteoarthritis (bone-on-bone contact or knee subluxation);
7. Patients who refuse second-look arthroscopy or participation in the study;
8. Patients unable to complete at least 12 months of follow-up;
9. Patients with severe osteoporosis;
10. Patients with cognitive impairment.

No IPD sharing is planned due to the high re-identification risk from radiographs/CT/MRI and 3D gait waveforms under our institution's privacy policy.