High Tibial Osteotomy

Rationale: Too young for TKA (lifetime revision guaranteed with modern life expectancy). HTO provides 15-20 year delay to TKA, preserves bone stock for future surgery.

Approach:

• HTO first-line treatment if meets criteria (isolated medial OA, stable ligaments, good ROM)
• Consider adjunct biologics (PRP, microfracture) to enhance cartilage healing
• Meniscal allograft transplantation if post-meniscectomy
• Counsel about realistic expectations (joint preservation, not cure)

Expected outcome: 90% good-excellent at 10 years, median HTO survival 15+ years, converts to TKA around age 55-60.

This approach maximizes "joint-years" before eventual arthroplasty.

Rationale: Ideal HTO age window. Active lifestyle preservation important. HTO provides 12-15 year delay to TKA with excellent outcomes.

Approach:

• HTO first-line recommendation if ideal candidate (see selection criteria)
• Detailed informed consent about outcomes, durability, rehab requirements
• TKA offered as alternative for low-demand patients who prefer "definitive" solution
• Shared decision-making based on activity goals, occupation, patient preference

Expected outcome: 85-90% good-excellent at 10 years, 40% convert to TKA by 15 years, HTO does not compromise subsequent TKA results.

This is the "sweet spot" for HTO with maximum benefit-risk ratio.

Rationale: Transition zone - HTO may provide 8-12 year bridge to TKA, or TKA may last patient's lifetime. Decision based on activity level, demand, bone quality, comorbidities.

Approach:

• Present both options with realistic expectations for each
• HTO advantages: Joint preservation, maintain bone stock, higher activity level allowed
• TKA advantages: Definitive solution, faster recovery, may last lifetime (15-20 year modern TKA survival)
• Patient-driven decision based on values, goals, risk tolerance

Expected outcome HTO: 70-80% good-excellent at 10 years. Expected outcome TKA: 90-95% survivorship at 15 years.

Counsel that either choice is reasonable - no "wrong" answer with informed consent.

Rationale: Limited HTO durability (5-7 years median survival over age 65). TKA provides definitive treatment with excellent results and likely to last lifetime.

Approach:

• TKA first-line recommendation
• HTO considered only for: very high-demand patients, significant comorbidities making TKA high-risk, patient strong preference for joint preservation despite poor prognosis
• If HTO performed, detailed consent about limited durability and high conversion rate

Expected outcome HTO: 50-60% survival at 10 years, 60% convert to TKA by 10 years. Expected outcome TKA: 90-95% survivorship at 15 years.

TKA is the evidence-based recommendation for this age group.

Supine on radiolucent table (Jackson table or standard table with bump). Leg positioning: thigh tourniquet (300mmHg) inflated after exsanguination. Knee flexed 20-30° over bump or sandbag (relaxes soft tissues, opens medial side). Foot secured with leg holder or sandbag (prevents rotation during correction).

Position C-arm for perfect AP (tibial spines centered between femoral condyles) and perfect lateral (femoral condyles superimposed). Check full knee and proximal tibia visible on both views. Test ability to obtain full-length mechanical axis view (from hip to ankle) if using cable technique.

Prep from mid-thigh to ankle, including medial malleolus (for cable technique). Waterproof drape over bump. Free draping of leg allows manipulation during correction. Mark medial joint line, tibial tubercle, pes anserinus with marking pen.

Oblique incision 5-6cm long, starting 1cm posteromedial to tibial tubercle, 4cm distal to joint line, extending distally and anteriorly at 45° angle toward the tibial crest. Stay posterior to superficial MCL to preserve ligament integrity. Incise skin and subcutaneous tissue sharply.

Identify pes anserinus (sartorius, gracilis, semitendinosus tendons) inserting on anteromedial tibia. Retract posteriorly (protect sartorial branch of saphenous nerve). Alternatively, release pes insertion and tag for later repair (some surgeons prefer this for better exposure).

Superficial MCL runs obliquely from medial epicondyle to tibia 5-7cm distal to joint. Stay anterior to MCL (subperiosteal dissection on tibia). Place anterior retractor (Hohmann) on anterolateral tibia (under patellar tendon). Place posterior retractor carefully to protect MCL and neurovascular structures.

Subperiosteal dissection with elevator along medial and anterior tibia. Expose from 3cm distal to joint to 10cm distally. Posterior periosteum must be elevated carefully (popliteal vessels at risk). Place curved elevator posteriorly and maintain throughout case to protect vessels during sawing.

Under fluoroscopy (perfect AP and lateral), insert 2.0mm K-wire from anteromedial tibia, aiming toward superior fibular head. Entry point is 3.5-4cm distal to medial joint line (ensures adequate proximal fragment for fixation). Angle: 5-10° ascending (cephalad), staying 1-1.5cm below medial joint line to avoid intra-articular violation. Check on lateral view: wire should be in anterior half of tibia (posterior cortex hinge preserved). Parallel second K-wire 5mm distal for saw guide.

Using oscillating saw (not sagittal saw - less vibration), make ascending cut along proximal K-wire from anteromedial cortex toward lateral cortex. Stop 1cm from lateral cortex (confirmed with fluoroscopy - leave lateral cortex intact). Cut should stay parallel to joint line (avoid intra-articular extension). Depth control: use graduated saw blade markings, stop at ~35-40mm for average tibia.

Make descending cut from anterolateral tibial cortex (just lateral to tibial tubercle) directed posteriorly and slightly medially. This cut is perpendicular to ascending cut (forms an "L" or "hockey stick" shape). Stop 1cm from posterior cortex. This preserves posterior cortical hinge (critical for stability). Total osteotomy: incomplete circumferentially except medially where bone will hinge open.

Insert thin osteotome into osteotomy site from anteromedial side. Gently twist to propagate fracture toward lateral cortex. You should feel/hear a controlled fracture as lateral cortex gives way. Do not force - excessive force causes comminution. Check lateral cortex fracture on fluoroscopy. Posterior cortex should remain intact (hinge point).

Insert calibrated lamina spreaders (or dedicated HTO spreaders like Puddu osteotomy spreader) into osteotomy site. Open gradually in 1-2mm increments. Check fluoroscopy after each opening - ensure hinge fracture propagating correctly (lateral cortex fractures, posterior cortex bends). Avoid rapid opening (causes uncontrolled hinge fracture, posterior cortex disruption).

Cable method: Place electrocautery cable from center of femoral head (use hip fluoroscopy to identify) to center of ankle (between malleoli). Under fluoroscopy, cable should pass through knee. Measure distance from cable to medial edge of tibial plateau. Target: 62-65% of plateau width from medial edge. Open or close spreader to achieve target. Record gap size with calibrated spreaders.

If using computer navigation: System displays mechanical axis in real-time. Open spreader until navigation shows axis at target (usually 3-5° valgus overcorrection, or 62-65% tibial width). Navigation accounts for soft tissue laxity and joint opening (more accurate than cable). Lock spreaders when target achieved.

With spreaders locked at target correction, assess gap size at anteromedial cortex. Measure with ruler or graduated spreader. Gap under 10mm: Bone graft optional (modern locking plates sufficient). Gap 10-15mm: Consider bone graft (allograft chips or autograft). Gap over 15mm: Bone graft strongly recommended (high nonunion risk). Check posterior tibial slope change on lateral fluoroscopy (should increase ~2° per 5mm opening - acceptable if total increase under 5°).

Select TomoFix plate size (medium for small/average tibia, large for large tibia). Position plate on anteromedial tibia with proximal end just below joint line. Plate should sit flush against bone. First screw: Insert superior-most non-locking screw through oblong hole while maintaining compression across plate-bone interface. This acts as reduction screw (seats plate).

Remove spreaders. Insert 3 proximal locking screws (bicortical, 3.5mm locking screws). These screws lock into plate and provide angular stability to maintain correction. Drill with locking drill guide to ensure proper thread engagement. Measure depth carefully - avoid penetrating far posteriorly (popliteal vessels). Check fluoroscopy: Screws should not violate joint (stay 5mm below joint line).

If gap over 10mm, insert bone graft into wedge before final screw insertion. Options: Allograft chips (most common - DBM or cancellous chips), autograft (from proximal tibia or iliac crest), bone graft substitute (calcium phosphate, calcium sulfate). Pack graft into defect posteriorly first, then anteriorly. Goal: fill 60-70% of gap (overfilling prevents correction loss).

Insert remaining distal locking screws (typically 3 screws). Distal screws can be unicortical (reduces operative time, no posterior cortex risk). Use locking drill guide. Tighten all screws sequentially. Final fluoroscopy check: AP and lateral views confirm plate position, screw length, maintenance of correction, no intra-articular hardware, posterior cortex intact.

With all screws inserted, test stability: Gently stress knee into varus - should have minimal give (under 2mm movement). If unstable, consider additional screw or revision of fixation. Range of motion: Flex knee to 90° (ensure no impingement, screws not too long). Alignment recheck: Verify mechanical axis with cable or navigation one final time before closure.

Drain: Most surgeons do NOT use drain for HTO (increases bleeding, no benefit shown). If large gap with extensive dissection, consider small suction drain (10Fr JP) exiting inferiorly, remove at 24 hours. Release tourniquet before closure, achieve hemostasis with electrocautery.

Repair pes tendons if released (Krackow stitch with #2 Ethibond to drill holes in tibia). Close periosteum and fascia with running #1 Vicryl (reapproximate tissues over plate to reduce hardware prominence). Irrigate copiously (3L saline - reduce infection risk).

Subcutaneous layer: 2-0 Vicryl interrupted. Skin: 3-0 nylon interrupted vertical mattress (excellent eversion, easy removal) OR subcuticular 3-0 Monocryl (cosmetic, no removal needed). Dressing: Absorbent dressing (anticipate oozing), compressive wrap (ACE wrap from toes to thigh). Hinged knee brace locked in extension (allows early controlled ROM, protects correction).

Supine with bump under ipsilateral hip (internally rotates leg, exposes lateral knee). Tourniquet on thigh. C-arm positioned for AP/lateral fluoroscopy of knee and proximal tibia/fibula.

Incision: 4cm longitudinal incision over proximal fibula, 8-10cm distal to fibular head. Identify common peroneal nerve (palpable posterior to fibular head - do not dissect - increases palsy risk). Subperiosteal elevation of peroneus longus off fibula. Osteotomy: Transverse fibular cut 8cm distal to head with oscillating saw. Remove 1cm segment to allow tibia to close. Closure: Interrupted sutures, nerve padded with local tissue.

Incision: Longitudinal incision 8-10cm over lateral tibia, centered 3-4cm distal to joint line. Raise anterolateral skin flap. Incise iliotibial band longitudinally. Subperiosteal dissection medially (protect anterior tibial vessels posteriorly). Expose tibia from joint line to 10cm distally.

Under fluoroscopy, mark proximal cut (1.5cm below joint line, parallel to joint). Mark distal cut (converging toward medial cortex). Wedge base laterally = desired correction (1mm base ≈ 1° correction). Make cuts with oscillating saw. Leave 1cm medial cortex hinge intact. Remove wedge with rongeur/osteotome. Close wedge manually (compress with bone clamps). Hinge fractures medially in controlled fashion.

Staple fixation (historical - less stable), OR lateral locking plate (modern - more stable). Insert 3-4 screws proximally, 3-4 distally (all bicortical). Compression across osteotomy achieved with eccentric screw or compression screw. Check alignment with cable/fluoroscopy. AP/lateral films confirm closure, alignment, hardware position.

Return to fibular incision. Decompress common peroneal nerve: Release fascial bands around fibular neck without direct nerve dissection. This reduces postoperative palsy risk (still 5-10% despite decompression). Close in layers, place drain if needed.

Weight-bearing: Toe-touch only (10-20lbs) with crutches and hinged brace locked in extension. ROM: Remove brace for gentle ROM exercises 0-90° from day 1 (prevent stiffness). Pain control: Multimodal analgesia (acetaminophen, NSAIDs from day 3, opioids sparingly). Wound care: Keep dry until suture removal day 14. DVT prophylaxis: Aspirin 325mg daily for 4 weeks (or enoxaparin in high-risk patients). Elevation: Leg elevated when resting to reduce swelling. Ice: 20min q2-3h. Radiographs: AP/lateral knee at 2 weeks to confirm alignment maintained.

Weight-bearing: Progress to 25% body weight weeks 2-4, then 50% body weight weeks 4-6. Advance based on pain tolerance and radiographic healing. ROM: Advance to 0-120° flexion by week 6. Strengthening: Isometric quadriceps sets, straight leg raises, ankle pumps. Brace: Continue hinged brace, unlock for ROM exercises. Radiographs: AP/lateral at 6 weeks - assess for callus formation, maintained alignment, no hardware failure.

Weight-bearing: Advance to full weight-bearing by week 8-10 if radiographic healing progressing (bridging callus on 3/4 cortices). Wean crutches gradually. ROM: Achieve full ROM by week 12. Strengthening: Closed-chain exercises (leg press, mini squats), resistance band strengthening. Proprioception: Balance board, single-leg stance. Brace: Discontinue brace at 8-10 weeks if stable. Radiographs: AP/lateral at 12 weeks - confirm union, maintained correction.

Activities: Low-impact activities (cycling, swimming, elliptical) from 3 months. Impact activities (jogging, court sports) from 4-6 months if full strength and ROM. Radiographs: AP/lateral at 6 months - confirm consolidation, assess alignment. Function: Expect 80-90% functional recovery by 6 months.

Follow-up: Annual clinical and radiographic follow-up for 3-5 years (assess for progression of OA, loss of correction). Hardware removal: Consider at 18-24 months if symptomatic prominence (not routine). Activity modification: Avoid high-impact activities long-term (running marathons, jumping sports) - protect durability. Patient education: HTO is joint preservation, not cure - may need TKA in 10-15 years.

Weight-bearing: Weight-bearing as tolerated from day 1 with crutches (compression fixation is stable). ROM: 0-90° from day 1, unlocked brace. Pain control and prophylaxis: Same as opening wedge. Radiographs: 2 weeks AP/lateral.

Weight-bearing: Progress to full weight-bearing by week 4 (most patients off crutches by 3-4 weeks). ROM: Full ROM by week 6. Strengthening: Advance quicker than opening wedge. Radiographs: 6 weeks confirm healing (expect union by 8-10 weeks).

Activities: Return to impact activities from 3 months (faster than opening wedge). Radiographs: 3 months confirm union. Expected outcome: 90% functional recovery by 4 months.