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High Tibial Osteotomy with Concurrent ACL Reconstruction - Medial Opening Wedge

Surgical technique guide for High Tibial Osteotomy with Concurrent ACL Reconstruction - Medial Opening Wedge - FRCS exam preparation

Core Procedure
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By OrthoVellum Medical Education Team

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High-yield overview

Arthroscopic for ACL assessment and reconstruction. Mini-open anteromedial approach for HTO. Hamstring harvest incision for ACL graft. Separate incisions to avoid wound complications. | advanced

Critical Danger Structures

Common Peroneal Nerve

Location: Wraps around fibular neck laterally, 2-3cm distal to fibular head. Protection: Avoid lateral dissection beyond preserved hinge (5-10mm from lateral cortex), gentle opening without excessive valgus force, monitor for traction injury during correction

Popliteal Neurovascular Bundle

Location: Posterior to proximal tibia, 1-2cm posterior to posterior tibial cortex at osteotomy level. Protection: Place Hohmann retractor posteriorly around tibia before osteotomy, protect with retractor during saw cuts, avoid deep posterior saw penetration

Saphenous Nerve & Vein

Location: Medial subcutaneous, beneath sartorius fascia near hamstring harvest site. Protection: Use separate incisions for HTO and hamstring harvest (3-4cm separation), gentle dissection medially, identify and protect during pes anserinus exposure

Medial Collateral Ligament Superficial Fibers

Location: Superficial MCL fibers anterior to pes anserinus insertion on proximal medial tibia. Protection: Elevate pes anserinus distally preserving MCL anterior fibers, avoid excessive periosteal stripping, maintain MCL integrity for knee stability

ACL Tunnel Zone & HTO Plate Interface

Location: Tibial ACL tunnel must avoid HTO plate - plate spans osteotomy site 3-4cm distal to joint line. Protection: Plan HTO osteotomy 3-4cm distal to joint (avoid ACL tunnel interference), tibial tunnel starts 2-3cm proximal to plate, fluoroscopy confirms no hardware conflict

Mnemonic

VARUSVARUS - Combined HTO-ACL Indications

Hook:Use VARUS to systematically identify patients who need COMBINED procedure rather than isolated ACL reconstruction - each letter represents biomechanical rationale

Mnemonic

FUJISAWAFUJISAWA - Target Correction & Planning

Hook:FUJISAWA point is THE target for combined HTO-ACL - memorize 62-65% across plateau = 3-5° valgus for exam vivas. Examiners expect precise mechanical axis understanding

Positioning and Preparation

Patient Position: Supine on radiolucent table. Bump under ipsilateral hip for neutral rotation. Tourniquet thigh (optional, deflate before fixation). Fluoroscopy essential (mini C-arm). Leg holder or foot triangle for ACL portion. Ensure access to entire lower limb for cable alignment measurement.

Surgical Approach: Arthroscopic for ACL assessment and reconstruction. Mini-open anteromedial approach for HTO. Hamstring harvest incision for ACL graft. Separate incisions to avoid wound complications.

Incision: Anteromedial HTO incision (5-7cm oblique) - 3-4cm distal to joint line, starting medial to tibial tubercle extending posteromedially. Separate hamstring harvest incision (3-4cm oblique) over pes anserinus to reduce wound complications. Standard arthroscopy portals (anterolateral, anteromedial).

Absolute Indications

  • ACL deficiency with varus malalignment >3-5° mechanical axis - isolated ACL reconstruction has 20-40% failure rate in varus knees vs 5-10% in neutral, HTO correction protects graft from varus thrust
  • ACL tear with medial compartment early OA (Outerbridge 2-3, Kellgren-Lawrence 1-2) in young active patient (<55-60 years) - combined procedure offloads medial compartment while providing stability
  • ACL tear with medial meniscal deficiency (root tear, subtotal meniscectomy, irreparable meniscal tear) - HTO offloads medial compartment protecting remaining meniscus and ACL graft
  • Revision ACL reconstruction in varus knee - if primary ACL failed due to varus malalignment, revision requires HTO to correct biomechanics

Relative Indications

  • ACL tear with varus 2-3° AND medial symptoms - borderline varus with medial pain, younger age, high activity demands
  • Prophylactic HTO with ACL in varus 3-5° - prevent future medial OA progression and graft failure in young athletic patient

Contraindications

Absolute:

  • Advanced medial compartment OA (Outerbridge grade 4, Kellgren-Lawrence 3-4, bone-on-bone) - consider UKA or TKA instead
  • Inflammatory arthropathy (rheumatoid arthritis, psoriatic arthritis) - not mechanical problem, disease will progress
  • Infection (active or recent septic arthritis) - stage infection treatment before elective osteotomy
  • Severe peripheral vascular disease - healing impairment, ischemic complications
  • Patient unwilling/unable to comply with protected weight-bearing protocol - HTO requires 6-12 weeks TTWB for union

Relative:

  • Age >60-65 years - arthroplasty may be more appropriate, though biological age matters more than chronological
  • Obesity (BMI >35) - increased nonunion risk, mechanical failure, worse outcomes
  • Smoking - 3-4x increased nonunion risk, must quit 6-8 weeks preoperatively
  • Osteoporosis/poor bone quality - fixation failure risk, consider bone health optimization
  • Flexion contracture >15° - difficulty achieving full extension, affects ACL tunnel placement
  • Patellofemoral arthritis - may worsen with valgus correction or slope change
  • Ligamentous laxity (hypermobile patient) - HTO correction less predictable, consider other stabilization

Operative Technique

Step 1: Understanding Combined HTO-ACL Rationale

Understanding Combined HTO-ACL Rationale: BIOMECHANICAL CONCEPT: VARUS alignment increases MEDIAL compartment load (60-80% medial vs 20-40% lateral) and creates VARUS THRUST during gait. ACL deficiency in varus knee has: 1) Increased ANTERIOR tibial translation (ACL role), 2) Increased MEDIAL translation (varus thrust), 3) Accelerated MEDIAL OA from overload. ISOLATED ACL reconstruction in VARUS knee often FAILS from ongoing varus thrust and medial overload. COMBINED SURGERY RATIONALE: HTO corrects alignment to VALGUS (shifts load laterally), reducing medial compartment load and varus thrust. This PROTECTS ACL graft from ongoing stress AND protects medial compartment from OA progression. INDICATIONS for combined procedure: 1) ACL + varus >3-5°, 2) ACL + medial OA early stages, 3) ACL + medial meniscal deficiency, 4) Revision ACL in varus knee. SEQUENCING: Single-stage (HTO + ACL same surgery) vs two-stage (HTO first, ACL later). Single-stage preferred - one recovery, addresses both problems, ACL protected from day one.

Clinical Pearl

Technical Tip: EXAM KEY: 'Isolated ACL reconstruction in varus knee often fails because varus thrust continues to stress graft and medial compartment. I perform combined HTO-ACL to: 1) Correct alignment to valgus (offload medial, reduce varus thrust), 2) Protect ACL graft from ongoing stress, 3) Protect medial compartment and meniscus. Single-stage is preferred - one recovery, immediate benefit.'

Dangers at this step

  • Isolated ACL in varus >5° = high failure risk (20-40% vs 5-10% in neutral)
  • Isolated HTO without ACL in unstable knee = ongoing instability
  • Two-stage surgery = two recoveries, delayed return, higher cost
  • Patient expectation mismatch (complex surgery, long recovery)

Step 2: Preoperative Planning & Alignment Analysis

Preoperative Planning & Alignment Analysis: IMAGING ASSESSMENT: 1) ALIGNMENT RADIOGRAPHS: Full-length standing AP (hip-knee-ankle), measure mechanical axis deviation (MAD - mm from knee center), mechanical axis angle (hip center to ankle center), medial proximal tibial angle (MPTA, normal 85-90°). 2) STANDARD RADIOGRAPHS: Weight-bearing AP/lateral/skyline, flexion PA (Rosenberg), assess cartilage (joint space, osteophytes, sclerosis - Kellgren-Lawrence grade). 3) MRI: ACL status, menisci, cartilage grading (Outerbridge), bone marrow edema, posterior tibial slope (sagittal). ALIGNMENT CALCULATION: Current mechanical axis → Target mechanical axis (FUJISAWA POINT: 62-65% across tibial plateau from medial = 3-5° valgus). Use MINIACI METHOD or digital templating. Calculate WEDGE SIZE needed (mm of opening at osteotomy site). Typical 7-12mm opening for 3-5° correction. POSTERIOR SLOPE: the goal is to PRESERVE native slope (7-10°). A medial opening wedge tends to inadvertently INCREASE slope, which shifts the tibia anteriorly and increases ACL graft strain (Giffin AJSM 2004) - so plan anterior gap control (Noyes 3-triangle: anterior gap approximately half the posteromedial gap).

Clinical Pearl

Technical Tip: EXAM KEY: 'Preop planning is CRITICAL. I measure mechanical axis on full-leg standing films - calculate current MAD and angle. Target is FUJISAWA POINT: 62-65% across plateau or 3-5° valgus - offloads medial compartment and protects ACL. I use Miniaci method or digital templating to determine wedge opening needed, typically 7-12mm. CRITICAL for the ACL: I check posterior slope on lateral and aim to PRESERVE native slope - a medial opening wedge tends to inadvertently increase slope, and increased slope strains the ACL graft, so I control the anterior gap (Noyes 3-triangle).'

Dangers at this step

  • Under-correction (inadequate offloading, varus thrust persists, ACL graft failure)
  • Over-correction (excessive valgus causes lateral compartment overload, patellofemoral problems)
  • Inadvertent posterior slope increase from the opening wedge (shifts tibia anteriorly, increases ACL graft strain and re-rupture risk)
  • Operating without formal alignment films = guessing correction

Step 3: Diagnostic Arthroscopy & ACL Assessment

Diagnostic Arthroscopy & ACL Assessment: Standard AL and AM portals. Systematic arthroscopy: 1) ACL - confirm complete tear vs partial, stump quality, femoral/tibial insertion remnants. 2) MENISCI - medial meniscus extrusion? Root tear? Lateral meniscus OK? Repair vs debride vs transplant. 3) CARTILAGE - Outerbridge grading of medial/lateral compartments, patellofemoral joint. Confirm medial OA not advanced (grade 4 = consider UKA instead). 4) LOOSE BODIES, synovitis. DOCUMENT with photos. Address concurrent pathology: meniscal repair/debridement, chondroplasty, loose body removal. DO NOT create ACL tunnels yet (wait until after HTO - tunnels may shift with correction).

Clinical Pearl

Technical Tip: EXAM KEY: 'I perform diagnostic arthroscopy first to confirm ACL tear and assess compartments. I carefully grade medial cartilage - if grade 4 (bone-on-bone), patient may be better with UKA than HTO. I repair medial meniscus if possible (HTO protects repair). CRITICAL: I do NOT drill ACL tunnels yet - HTO will shift tibial tunnel position, so ACL tunnels AFTER HTO.'

Dangers at this step

  • Drilling ACL tunnels before HTO (tunnel position shifts with correction)
  • Proceeding with HTO in advanced medial OA (grade 4 = consider UKA)
  • Missing meniscal pathology requiring repair
  • Inadequate cartilage assessment

Step 4: Hamstring Graft Harvest for ACL

Hamstring Graft Harvest for ACL: HAMSTRING HARVEST: Oblique incision (3-4cm) over pes anserinus, 3cm distal and 2cm medial to tibial tubercle. This incision is SEPARATE from HTO incision to reduce wound complication risk. Incise sartorial fascia. Identify gracilis (superior) and semitendinosus (inferior) tendons. Strip with closed stripper to at least 24-26cm length (need longer than standard ACL due to HTO opening). Prepare 4-strand graft on back table: whipstitch both ends, measure diameter (target 8-10mm), pretension on graft board. Keep moist. Alternative: BPTB or quadriceps autograft (some prefer bone-bone healing with HTO bone work). Allograft option if patient prefers but autograft preferred for biology.

Clinical Pearl

Technical Tip: EXAM KEY: 'I harvest hamstrings through SEPARATE incision from HTO incision to reduce wound complications. I need LONGER graft than standard ACL (24-26cm minimum) because HTO opening increases tibia length slightly. I prepare 4-strand graft, 8-10mm diameter, and pretension. Some surgeons prefer BPTB for bone-to-bone healing with concurrent HTO bone work.'

Dangers at this step

  • Shared incision with HTO = wound complication risk
  • Graft too short (HTO increases tibial length)
  • Saphenous nerve/vein injury medially
  • Graft amputation from accessory bands

Step 5: HTO Osteotomy - Anteromedial Approach

HTO Osteotomy - Anteromedial Approach: INCISION: 5-7cm oblique incision, 3-4cm distal to joint line, starting 1cm medial to tibial tubercle extending posteromedially over pes anserinus insertion. DISSECTION: Incise fascia, elevate pes anserinus distally (can preserve or release), protect MCL superficial fibers anteriorly. EXPOSE PROXIMAL TIBIA medial surface. Retract pes muscles posteriorly. Insert Hohmann retractor POSTERIORLY around tibia (protects popliteal vessels) and LATERALLY (protects lateral soft tissues and peroneal nerve). Fluoroscopy to confirm location. MARK OSTEOTOMY: 3-4cm distal to medial joint line (avoid proximal tibial fixation zones for ACL), parallel to joint line. Osteotomy from medial cortex aimed toward FIBULAR HEAD on lateral side, STOPPING 5-10mm from lateral cortex (PRESERVE HINGE).

Clinical Pearl

Technical Tip: EXAM KEY: 'HTO incision is separate from ACL harvest. I expose medial proximal tibia, retract pes posteriorly, place Hohmann retractors posterior (protect popliteal vessels) and lateral (protect soft tissues). I mark osteotomy 3-4cm distal to joint, aimed at fibular head. Critical to START LOW ENOUGH to avoid ACL tunnel interference and PRESERVE LATERAL HINGE for stability.'

Dangers at this step

  • Osteotomy too proximal = interferes with ACL tunnels, intra-articular fracture risk
  • Popliteal vessels injury posteriorly (Hohmann retractor protects)
  • Common peroneal nerve injury laterally (careful lateral dissection)
  • MCL superficial fibers injury (impacts knee stability)
  • Violation of lateral hinge = unstable osteotomy, lateral translation

Step 6: Osteotomy Execution & Hinge Preservation

Osteotomy Execution & Hinge Preservation: TECHNIQUE: Multiple techniques - saw, osteotomes, or both. 1) OSCILLATING SAW: Create ANTERIOR and POSTERIOR cuts from medial cortex, parallel to joint, aiming at fibular head on lateral side. Cuts stop 5-10mm from lateral cortex. 2) OSTEOTOMES: Place osteotomes between saw cuts, gently spread to create opening. Protect hinge. Alternative: MULTIPLE DRILLING: 4.5mm drill holes along osteotomy line, then complete with osteotome (less heat, preserves biology). HINGE PRESERVATION is CRITICAL: Lateral cortex must stay intact for stability. Hinge width 5-10mm. Check fluoroscopy - ensure cuts stop short of lateral cortex. If hinge breaks: can still proceed but need fixation on lateral side (plate or screws) for stability.

Clinical Pearl

Technical Tip: EXAM KEY: 'I use oscillating saw for anterior and posterior cuts, parallel to joint, aiming at fibular head laterally. Critical to STOP 5-10mm from lateral cortex to preserve hinge. Hinge provides stability during opening and healing. I check with fluoroscopy. If hinge breaks (10-15% incidence), I add lateral plate or screws for stability but outcomes still good.'

Dangers at this step

  • Hinge fracture/violation = unstable osteotomy (can salvage with lateral fixation)
  • Intra-articular fracture (osteotomy too proximal)
  • Posterior cortex blowout (saw too deep posteriorly)
  • Thermal necrosis from saw (irrigate, use sharp blade)
  • Peroneal nerve injury if lateral dissection

Step 7: Gradual Opening & Alignment Correction

Gradual Opening & Alignment Correction: OPENING: Use graduated osteotome spreaders or specialized HTO opening instruments. Open GRADUALLY in 1-2mm increments. Monitor with FLUOROSCOPY: AP view shows opening gap, lateral view shows posterior slope. Use CABLE METHOD: Electrocautery cable from femoral head center to ankle center - check passes through FUJISAWA POINT (62-65% across plateau). Alternative: Use alignment rod under fluoroscopy. WEDGE SIZE: Typical 7-12mm opening at anterior cortex for 3-5° valgus correction. If using WEDGE SPACER/ALLOGRAFT: insert trial spacers to confirm size, then insert definitive spacer (metal, PEEK, allograft, or tricalcium phosphate). If NOT using spacer: leave gap for bone ingrowth. POSTERIOR SLOPE: Check lateral fluoroscopy and PRESERVE native slope. Keep the anterior (tubercle) gap approximately HALF the posteromedial gap (Noyes 3-triangle) - an equal or larger anterior gap will inadvertently raise slope, which is detrimental to the ACL graft. Every 1mm of anterior gap error changes slope by roughly 2°.

Clinical Pearl

Technical Tip: EXAM KEY: 'I open osteotomy gradually using spreaders, checking alignment with cable method under fluoroscopy - cable from femoral head to ankle should pass through Fujisawa point (62-65% across plateau). Typical opening 7-12mm at anterior cortex for 3-5° valgus. I check posterior slope on lateral view and aim to PRESERVE native slope by keeping the anterior gap about half the posteromedial gap - increased slope strains the ACL graft. I use a spacer (allograft or synthetic) to prevent collapse.'

Dangers at this step

  • Under-opening = inadequate correction, persistent varus, ACL failure
  • Over-opening = excessive valgus, lateral compartment overload, patellofemoral issues
  • Asymmetric opening (anterior vs posterior) = slope change (can be intentional)
  • No spacer = gap collapse (though some techniques allow this)
  • Hinge fracture during opening

Step 8: HTO Plate Fixation

HTO Plate Fixation: MEDIAL LOCKING PLATE: Use HTO-specific plate (Tomofix, Puddu, etc.) with locking screws. Plate spans osteotomy medially. POSITIONING: Plate centered on medial tibia, proximal screws in metaphysis, distal screws in diaphysis. TECHNIQUE: Hold plate with K-wires temporarily. Drill and insert LOCKING SCREWS: Typically 3-4 proximal, 3-4 distal, bicortical. Proximal screws in locking holes support opened gap. Check screw length - no intra-articular penetration (fluoroscopy), no lateral cortex excessive penetration. SPACER: If used, insert bone graft or synthetic wedge into gap before plate fixation to maintain correction and enhance healing. Check FINAL ALIGNMENT with cable/fluoroscopy: Mechanical axis through Fujisawa point (62-65%). STABILITY: Osteotomy should be stable - no toggle. If unstable, add lateral plate (rare if hinge intact).

Clinical Pearl

Technical Tip: EXAM KEY: 'I fix with medial locking plate - HTO-specific design. I hold reduction with K-wires, then insert locking screws - 3-4 proximal supporting the opened gap, 3-4 distal for stability. I insert spacer (bone graft or synthetic) to prevent collapse and enhance healing. Final fluoroscopy check: mechanical axis through Fujisawa point, no intra-articular screws, stable construct.'

Dangers at this step

  • Intra-articular screw penetration (check fluoroscopy)
  • Screw too long laterally = peroneal nerve, soft tissue irritation
  • Plate malposition = loss of correction
  • Inadequate screw purchase = fixation failure
  • No spacer = gap collapse, loss of correction (some techniques accept this)

Step 9: ACL Femoral Tunnel - Post-HTO

ACL Femoral Tunnel - Post-HTO: NOW perform ACL reconstruction (HTO completed and fixed). ARTHROSCOPY: Return to arthroscopic portals (AL, AM). Re-examine knee - confirm HTO didn't violate joint (rare). FEMORAL TUNNEL: Use ANATOMIC technique. Drill through ANTEROMEDIAL portal at 110-120° knee flexion. AIM: Center of femoral ACL footprint - use resident's ridge (lateral intercondylar ridge) and bifurcate ridge as landmarks. Position: 1-2mm anterior to over-the-top, on lateral wall of notch. Drill guide wire, confirm position arthroscopically and fluoroscopically (lateral view), over-drill with cannulated reamer matching graft diameter (typically 8-10mm). Depth: 25-30mm for suspensory fixation, deeper if interference screw. ENSURE tunnel does NOT conflict with HTO plate (usually no issue - femoral tunnel is femur, HTO is tibia).

Clinical Pearl

Technical Tip: EXAM KEY: 'After HTO fixed, I proceed to ACL. I drill femoral tunnel through AM portal at 110-120° flexion using anatomic technique - center of footprint using resident's ridge as landmark. Tunnel 8-10mm matching graft diameter. HTO doesn't affect femoral tunnel since it's on femur, but tibial tunnel position DOES change from HTO correction.'

Dangers at this step

  • Posterior wall blowout (tunnel too posterior)
  • Short tunnel (tunnel too anterior)
  • Non-anatomic position = graft failure
  • Confluence with HTO hardware (rare)

Step 10: ACL Tibial Tunnel - Adjusted for HTO

ACL Tibial Tunnel - Adjusted for HTO: TIBIAL TUNNEL is CRITICAL and ADJUSTED for HTO. HTO correction SHIFTS tibial tunnel position: Valgus correction shifts tunnel slightly LATERALLY and ANTERIORLY. Must account for this. TECHNIQUE: Use TIBIAL GUIDE at 55° angle (or adjust based on slope). AIM: Center of ACL footprint on tibia (just anterior to tibial spine, lateral to medial spine). START POINT: Typically anteromedial, PROXIMAL to HTO plate (2-3cm above plate) to avoid hardware. May need to start slightly LATERAL compared to standard ACL to avoid HTO plate. Drill guide wire, confirm position ARTHROSCOPICALLY (footprint center) and FLUOROSCOPICALLY (avoid HTO plate, proper angle). Over-drill with cannulated reamer. ENSURE: 1) Tunnel avoids HTO plate, 2) Tunnel exits at proper footprint position, 3) Tunnel parallel to Blumensaat's line in extension.

Clinical Pearl

Technical Tip: EXAM KEY: 'Tibial tunnel is ADJUSTED for HTO - valgus correction shifts anatomy. I use tibial guide aimed at footprint center but start point is PROXIMAL to HTO plate (2-3cm above) to avoid hardware. I may need to start slightly lateral. I check fluoroscopy - tunnel must avoid plate, exit at footprint, parallel to Blumensaat's. This is technically challenging part of combined surgery.'

Dangers at this step

  • Tunnel collision with HTO plate (plan trajectory carefully)
  • Tunnel too anterior = graft impingement
  • Tunnel too posterior = vertical graft
  • Non-anatomic footprint = graft failure
  • Fracture through HTO or tunnel site (rare)

Step 11: ACL Graft Passage & Femoral Fixation

ACL Graft Passage & Femoral Fixation: GRAFT PASSAGE: Pass sutures retrograde through tibial tunnel, through knee, out femoral tunnel. Pull graft into tibial tunnel, through knee, into femoral tunnel. ENSURE: Graft not twisted, graft at aperture of both tunnels, adequate graft length (remember HTO increased tibia length slightly - need longer graft). FEMORAL FIXATION: Use SUSPENSORY device (EndoButton, TightRope) - flip on far cortex of femur, pull graft tight, confirm button flipped (resistance, fluoroscopy). Alternative: Interference screw or cross-pin. Hybrid fixation (suspensory + interference) popular for combined procedure to ensure robust fixation in setting of HTO bone work.

Clinical Pearl

Technical Tip: EXAM KEY: 'I pass graft through tunnels ensuring no twist. Graft must be LONGER than standard ACL because HTO increased tibial length. For femoral fixation, I use suspensory device - flip button on far cortex, pull tight. Some surgeons add interference screw (hybrid) for extra security in combined procedure with HTO bone work nearby.'

Dangers at this step

  • Graft too short (HTO increased length)
  • Graft twisted
  • Button not flipped
  • Graft laceration during passage

Step 12: ACL Graft Tensioning & Tibial Fixation

ACL Graft Tensioning & Tibial Fixation: GRAFT CYCLING: Cycle graft 20-30 times through full ROM to pre-tension and eliminate creep. TENSIONING: Tension graft with knee at 20-30° flexion with manual posterior drawer force. TIBIAL FIXATION: Most common = INTERFERENCE SCREW inserted through tibial tunnel alongside graft. Screw divergent from graft (parallel causes laceration). ENSURE: 1) Screw avoids HTO plate (usually 2-3cm separation), 2) Screw parallel to tunnel, 3) Full extension possible without impingement. Alternative: Suture post or button fixation on anterior tibia. FINAL ASSESSMENT: Full ROM especially extension, no impingement, Lachman negative, pivot shift negative, HTO alignment maintained.

Clinical Pearl

Technical Tip: EXAM KEY: 'I cycle graft 20-30 times, then tension at 20-30° flexion. Tibial fixation with interference screw - must ensure screw is DIVERGENT from graft and AVOIDS HTO plate (2-3cm separation). I confirm full extension without impingement and negative Lachman/pivot. This combined procedure protects ACL from varus thrust and protects medial compartment.'

Dangers at this step

  • Screw collision with HTO plate
  • Screw lacerating graft (must diverge)
  • Inadequate screw purchase
  • Loss of extension (catastrophic - re-do surgery)
  • Residual instability

Step 13: Final Assessment & Closure

Final Assessment & Closure: COMPREHENSIVE CHECK: 1) ALIGNMENT: Cable/fluoroscopy confirms mechanical axis through Fujisawa point (62-65%), 2) HTO: Stable fixation, plate positioned correctly, no intra-articular screws, 3) ACL: Full ROM especially extension, stable Lachman and pivot, no impingement, graft well-tensioned, 4) MENISCUS: Repairs stable if performed, 5) KNEE: Full ROM 0-130°+, no varus/valgus laxity, stable patellofemoral tracking. DEFLATE tourniquet (if used), ensure hemostasis. DRAIN: Consider drain for HTO site (controversial). CLOSURE: Close HTO incision in layers - periosteum if possible, subcutaneous, skin. Close ACL harvest site. Close arthroscopy portals. Compressive dressing. Knee brace in extension.

Clinical Pearl

Technical Tip: EXAM KEY: 'Final check is critical: Alignment through Fujisawa point (fluoroscopy), HTO stable, ACL stable with full extension and negative Lachman. I deflate tourniquet for hemostasis. I may use drain at HTO site. I close in layers and apply brace in extension. Post-op protocol is PROTECTIVE - both HTO (bone healing) and ACL (graft healing) need protection.'

Dangers at this step

  • Misalignment unrecognized (under/over-correction)
  • Loss of extension
  • ACL instability
  • Hemarthrosis from HTO bone work
  • Wound complication (two incisions near each other)

Step 14: Postoperative Rehabilitation - Dual Protocol

Postoperative Rehabilitation - Dual Protocol: COMPLEX REHAB balancing HTO bone healing and ACL graft healing. PHASE 1 (0-6 weeks): TOE-TOUCH weight-bearing ONLY (10-20kg max) - HTO bone needs protected healing. Brace locked in extension for ambulation. ROM exercises 0-90° (avoid deep flexion - stresses HTO and ACL). Quadriceps sets, SLR, ankle pumps. DVT prophylaxis (chemoprophylaxis + mechanical). PHASE 2 (6-12 weeks): Progressive weight-bearing - 25% at 6 weeks, 50% at 8 weeks, 75% at 10 weeks, WBAT by 12 weeks (AFTER HTO healing confirmed on radiographs). ROM to full. Stationary bike (light), pool therapy. PHASE 3 (3-6 months): Strengthening, proprioception, functional training. No impact yet. Swimming, elliptical. PHASE 4 (6-9 months): Sport-specific training. Light jogging at 6-9 months if asymptomatic. PHASE 5 (9-12 months): Gradual return to full sport at 9-12 months if: HTO healed (radiographs), ACL stable (examination, functional testing), full strength and ROM.

Clinical Pearl

Technical Tip: EXAM KEY: 'Rehab is PROTECTIVE and PROLONGED - balancing HTO bone healing (12 weeks) and ACL graft maturation (9-12 months). CRITICAL: Toe-touch weight-bearing for 6 weeks (protect HTO), progressive to WBAT by 12 weeks only after HTO healing confirmed on X-ray. Return to sport 9-12 months minimum - both procedures need full maturation. Patient must understand this is NOT standard ACL - much longer recovery.'

Dangers at this step

  • Early weight-bearing = HTO nonunion or malunion
  • Aggressive ROM = loss of correction, ACL graft stress
  • Early return to sport = ACL graft failure or HTO failure
  • Patient non-compliance (must understand dual healing requirements)

Step 15: Long-term Monitoring & Outcomes

Long-term Monitoring & Outcomes: SURVEILLANCE: Clinical follow-up 2 weeks (wound check), 6 weeks (start weight-bearing progression), 12 weeks (confirm HTO union, progress rehab), 6 months, 12 months, 24 months, then annually. IMAGING: Radiographs (AP, lateral) at each visit: assess HTO alignment maintenance, bone union (typically 12-16 weeks), ACL tunnel widening, hardware position, compartment joint space, OA progression. MRI at 12-24 months if concerned about ACL graft or meniscal repairs. OUTCOMES: Combined HTO-ACL has 80-90% good-excellent outcomes at 5 years if patient selection appropriate. HTO corrects alignment and offloads medial compartment. ACL provides stability. TOGETHER they address varus thrust and medial overload. Better outcomes than either procedure alone in varus + ACL knee. HARDWARE REMOVAL: Can remove HTO plate at 18-24 months after bone fully healed if hardware symptomatic (patient preference). FAILURE MODES: 1) HTO nonunion (2-5%), malunion, loss of correction (under-correction or over-correction), 2) ACL graft failure (5-15% - lower than isolated ACL in varus), 3) OA progression despite correction (disease already established), 4) Wound infection, hardware failure.

Clinical Pearl

Technical Tip: EXAM KEY: 'Long-term surveillance shows combined HTO-ACL has 80-90% good outcomes at 5 years - better than isolated ACL in varus knee. HTO typically unites 12-16 weeks. ACL graft matures 9-12 months. I monitor alignment on serial radiographs - loss of correction or nonunion requires revision. Hardware removal optional at 18-24 months. This combined procedure PROTECTS both ACL graft (from varus thrust) and medial compartment (from overload) - it's the gold standard for ACL in varus knee.'

Dangers at this step

  • HTO nonunion (2-5% - risk factors: smoking, obesity, infection)
  • Loss of correction (under or over) requiring revision
  • ACL graft failure (lower than isolated ACL in varus but still 5-15%)
  • OA progression despite correction
  • Hardware complications (loosening, breakage, prominent requiring removal)
  • Peroneal nerve palsy (1-2% - from valgus correction or hematoma)
  • Compartment syndrome (rare but devastating)
  • DVT/PE (major surgery, limited mobility)

Complications

Major Complications - Recognition, Prevention & Management

Post-operative Care

PHASE 1 (0-6 weeks): TOE-TOUCH weight-bearing ONLY (10-20kg max) with crutches - protect HTO bone healing. Brace locked in extension for ambulation. ROM 0-90° gentle passive. Quadriceps sets (no active extension against resistance), SLR, ankle pumps. Ice, elevation. DVT chemoprophylaxis (LMWH or DOAC) + mechanical (TED stockings, calf pumps). PHASE 2 (6-12 weeks): Progressive weight-bearing - 25% at 6 weeks (if radiographs show healing), 50% at 8 weeks, 75% at 10 weeks, WBAT by 12 weeks ONLY after radiographic HTO union confirmed. ROM to full. Stationary bike light resistance, pool walking, closed-chain exercises. PHASE 3 (3-6 months): Continue strengthening, proprioception, balance, functional exercises. No impact or pivoting. Swimming, elliptical OK. PHASE 4 (6-9 months): Sport-specific training if asymptomatic and HTO fully healed. Light jogging progression. PHASE 5 (9-12 months): Gradual return to full sport if: HTO healed (radiographs), ACL stable (examination, functional testing), full ROM, 90%+ strength compared to contralateral. SURVEILLANCE: Follow-up 2 weeks, 6 weeks, 12 weeks (confirm HTO union), 6 months, 12 months, 24 months, annually. Radiographs each visit (alignment, union, hardware). MRI at 12-24 months if concerns. Hardware removal elective at 18-24 months if symptomatic.

Clinical Decision Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

CLINICAL PROMPT

"A 32-year-old amateur footballer presents with ACL-deficient knee and varus alignment. His full-length standing films show 6° varus mechanical axis. Describe your management approach and justify combined HTO-ACL reconstruction."

PRACTICAL APPROACH
This patient has ACL deficiency with significant varus malalignment (6°), which is a classic indication for combined HTO-ACL reconstruction rather than isolated ACL. My approach would be: ASSESSMENT - confirm ACL tear on MRI, assess medial compartment for early OA (Outerbridge grading), evaluate menisci for concurrent pathology, measure mechanical axis precisely on full-length standing films (MAD and mechanical axis angle). RATIONALE for combined procedure - isolated ACL in varus >5° has 20-40% failure rate vs 5-10% in neutral because varus thrust persists, causing ongoing stress on ACL graft and medial compartment overload. Combined HTO-ACL addresses BOTH biomechanical problems: HTO corrects alignment to valgus (target Fujisawa point 62-65% across plateau = 3-5° valgus), eliminating varus thrust and offloading medial compartment. ACL provides knee stability. TOGETHER they optimize biomechanics and protect both graft and cartilage. PREOPERATIVE PLANNING - full-length standing films to calculate mechanical axis, Miniaci method to determine wedge opening (typically 7-12mm for 3-5° correction), MRI for cartilage grading and ACL/meniscus status, counsel patient on complex surgery with 9-12 month return to sport. SURGICAL SEQUENCE - single-stage procedure: diagnostic arthroscopy (confirm ACL, grade cartilage, address meniscus), hamstring harvest (separate incision), HTO (medial opening wedge, plate fixation, confirm alignment with cable method), THEN ACL reconstruction (tunnels POST-HTO to account for alignment shift). This combined approach gives 80-90% good outcomes at 5 years, superior to isolated ACL in varus knee.
CLINICAL SCENARIOStandard

CLINICAL PROMPT

"During combined HTO-ACL procedure, you open the medial osteotomy and hear a crack - the lateral hinge has fractured. How do you manage this intraoperatively and does it change your plan?"

PRACTICAL APPROACH
Lateral hinge fracture occurs in 10-15% of opening wedge HTOs and can be managed successfully. My immediate response: ASSESSMENT - confirm hinge fracture with fluoroscopy (AP and lateral views), determine extent - complete vs incomplete, assess stability when holding correction. MANAGEMENT depends on stability: If STABLE (fracture but still hinged) - I can PROCEED with original plan. Open to planned correction (7-12mm), use spacer or bone graft to fill gap, apply medial locking plate (3-4 screws proximal, 3-4 distal), confirm alignment with cable method. The hinge fracture heals with the osteotomy - outcomes still good even with hinge fracture if stable fixation achieved. If UNSTABLE (completely broken hinge, gap laterally) - I ADD lateral stabilization. Options: lateral plate (second plate on lateral side for direct fixation), lateral screws (percutaneous screws from medial plate across gap into lateral cortex), or lateral external fixator pins (rare). This provides stability until healing. CONTINUE with ACL portion - hinge fracture doesn't affect ACL reconstruction, tunnels are independent. POSTOPERATIVE MANAGEMENT - potentially more PROTECTIVE weight-bearing (may extend toe-touch period to 8 weeks instead of 6 weeks if concern about hinge healing), closer radiographic monitoring for loss of correction. OUTCOMES - literature shows hinge fracture increases nonunion risk slightly but with stable fixation, outcomes are similar to intact hinge. I would counsel patient about hinge fracture, reassure that we can manage it, proceed with surgery. KEY POINT - hinge fracture is NOT a disaster, it's a recognized complication with established management strategies.
CLINICAL SCENARIOStandard

CLINICAL PROMPT

"You are planning the ACL tibial tunnel after completing HTO fixation. Describe how the HTO correction affects your tunnel placement and how you avoid collision with the HTO plate."

PRACTICAL APPROACH
This is the technically challenging part of combined HTO-ACL - tibial tunnel placement must account for alignment change and avoid hardware. My approach: UNDERSTAND ANATOMICAL SHIFT - valgus correction from HTO shifts tibial anatomy: tibial tunnel footprint appears more LATERAL and ANTERIOR relative to hardware compared to pre-correction position. The tunnel trajectory must be adjusted. PREOPERATIVE PLANNING - on preop imaging and templating, I plan HTO osteotomy at least 3-4cm distal to joint line. This provides adequate bone bridge between joint line (where ACL tunnel emerges) and osteotomy site (where plate sits). Standard ACL tunnel starts anteromedially on tibia - with HTO plate on medial side, I may need to adjust START POINT slightly lateral. INTRAOPERATIVE TECHNIQUE - use tibial guide at 55° angle (or adjust based on posterior slope), AIM for center of ACL footprint (arthroscopic view - just anterior to tibial spine, lateral to medial spine). START POINT is KEY - typically 2-3cm PROXIMAL to HTO plate to provide clearance. I may need to start slightly LATERAL compared to standard ACL to angle around plate. I place guide wire and CHECK position: ARTHROSCOPICALLY - confirm wire exits at proper footprint center. FLUOROSCOPICALLY - confirm wire avoids HTO plate (both AP and lateral views), proper tunnel angle, parallel to Blumensaat's line in extension. If wire trajectory risks plate collision - ADJUST before drilling. Move start point more lateral or more proximal, re-angle guide, re-check fluoroscopy. Once wire position confirmed safe - over-drill with cannulated reamer matching graft diameter (8-10mm). ENSURE adequate bone bridge between tunnel and plate (at least 10-15mm separation). FINAL CHECK - pass graft through tunnel, ensure no hardware impingement. Fixation with interference screw - screw must be DIVERGENT from graft (parallel causes laceration) and must avoid HTO plate. I check fluoroscopy before inserting screw. This careful planning and intraop verification prevents hardware collision - it requires more time and fluoroscopy than standard ACL but is essential for combined procedure.

High Tibial Osteotomy with Concurrent ACL Reconstruction - Exam Summary

Clinical summary

Evidence Base

Indications and outcomes of simultaneous high tibial osteotomy and ACL reconstruction (systematic review)

2a
Stride D, Wang J, Horner NS, Alolabi B, Khanna V, Khan M • Knee Surg Sports Traumatol Arthrosc
Clinical Implication: Combined HTO and ACL reconstruction is a valid option for the varus, ACL-deficient knee with reproducible alignment correction and functional gains, but counsel patients that graft failure and ongoing OA progression remain real risks - it is not a guaranteed disease-modifying procedure.
Verify on PubMed (PMID 30737516)

Tibial slope correction combined with second revision ACL produces good knee stability and prevents graft rupture

4
Dejour D, Saffarini M, Demey G, Baverel L • Knee Surg Sports Traumatol Arthrosc
Clinical Implication: In ACL surgery, REDUCING an excessive posterior tibial slope protects the graft from fatigue failure. This is the inverse of the common misconception that slope should be increased - in the ACL-deficient or revision knee, slope reduction (not augmentation) is protective.
Verify on PubMed (PMID 26298711)

Effects of increasing tibial slope on the biomechanics of the knee (cadaveric robotic study)

5
Giffin JR, Vogrin TM, Zantop T, Woo SL, Harner CD • Am J Sports Med
Clinical Implication: Provides the biomechanical basis for slope management in combined HTO-ACL: increased posterior slope drives anterior tibial translation and loads the ACL, so in the ACL-deficient knee native slope must be preserved (or reduced if pathologically high), never deliberately increased.
Verify on PubMed (PMID 14977661)

Opening wedge tibial osteotomy: the 3-triangle method to correct axial alignment and tibial slope

5
Noyes FR, Goebel SX, West J • Am J Sports Med
Clinical Implication: A medial opening wedge inadvertently increases slope unless the anterior gap is deliberately controlled. The 3-triangle principle gives a practical intraoperative rule for keeping slope neutral - critical when an ACL graft is also being protected.
Verify on PubMed (PMID 15716253)

Proximal tibial osteotomy for osteoarthritis with varus deformity: ten to thirteen-year follow-up

4
Hernigou P, Medevielle D, Debeyre J, Goutallier D • J Bone Joint Surg Am
Clinical Implication: Precise overcorrection into mild valgus is essential for durable HTO outcomes and underpins the Fujisawa target. Both under- and over-correction are penalised, justifying meticulous full-length alignment planning in the combined procedure.
Verify on PubMed (PMID 3818700)

References

  1. Bonnin M, Chambat P. Current concepts in opening wedge high tibial osteotomy. Orthop Traumatol Surg Res. 2010;96(8):937-945. DOI: 10.1016/j.otsr.2010.08.004

  2. Noyes FR, Goebel SX, West J. Opening wedge tibial osteotomy: the 3-triangle method to correct axial alignment and tibial slope. Am J Sports Med. 2005;33(3):378-387. PMID: 15716253. DOI: 10.1177/0363546504269034

  3. Dejour H, Bonnin M. Tibial translation after anterior cruciate ligament rupture. Two radiological tests compared. J Bone Joint Surg Br. 1994;76(5):745-749. PMID: 8083263

  4. Hernigou P, Medevielle D, Debeyre J, Goutallier D. Proximal tibial osteotomy for osteoarthritis with varus deformity. A ten to thirteen-year follow-up study. J Bone Joint Surg Am. 1987;69(3):332-354. PMID: 3818700

  5. Lattermann C, Jakob RP. High tibial osteotomy alone or combined with ligament reconstruction in anterior cruciate ligament-deficient knees. Knee Surg Sports Traumatol Arthrosc. 1996;4(1):32-38. DOI: 10.1007/BF01565995

  6. Dejour D, Saffarini M, Demey G, Baverel L. Tibial slope correction combined with second revision ACL produces good knee stability and prevents graft rupture. Knee Surg Sports Traumatol Arthrosc. 2015;23(10):2846-2852. PMID: 26298711. DOI: 10.1007/s00167-015-3758-6

  7. Stride D, Wang J, Horner NS, Alolabi B, Khanna V, Khan M. Indications and outcomes of simultaneous high tibial osteotomy and ACL reconstruction: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2019;27(4):1320-1331. PMID: 30737516. DOI: 10.1007/s00167-019-05379-5

  8. Naudie DD, Amendola A, Fowler PJ. Opening wedge high tibial osteotomy for symptomatic hyperextension-varus thrust. Am J Sports Med. 2004;32(1):60-70. DOI: 10.1177/0363546503258907

  9. Giffin JR, Vogrin TM, Zantop T, Woo SL, Harner CD. Effects of increasing tibial slope on the biomechanics of the knee. Am J Sports Med. 2004;32(2):376-382. PMID: 14977661. DOI: 10.1177/0363546503258880

  10. Song EK, Seon JK, Park SJ, Jeong MS. The complications of high tibial osteotomy: closing- versus opening-wedge methods. J Bone Joint Surg Br. 2010;92(9):1245-1252. DOI: 10.1302/0301-620X.92B9.23660

  11. Staubli AE, De Simoni C, Babst R, Lobenhoffer P. TomoFix: a new LCP-concept for open wedge osteotomy of the medial proximal tibia--early results in 92 cases. Injury. 2003;34 Suppl 2:B55-62. PMID: 14580986. DOI: 10.1016/j.injury.2003.09.025