High Yield Overview

TOTAL HIP REPLACEMENT - SUPERPATH/SUPERCAP APPROACH (TISSUE-SPARING POSTERIOR)

SuperPATH/SuperCAP - Minimally invasive tissue-sparing posterior approach using superior capsular window with preservation of external rotators (piriformis, obturator internus, gemelli, quadratus femoris) and posterior capsule intact. NO release of external rotators or posterior capsule unlike traditional posterior approach. Uses internervous plane between superior gluteal nerve (abductors) and inferior gluteal nerve (gluteus maximus) - same as traditional posterior. | consultant

Critical Danger Structures

Danger 1: Sciatic Nerve

Location: 1-2cm posterior to posterior capsule, exits sciatic notch below piriformis

Protection: MORE protected than conventional because preserved external rotators and capsule act as barrier. Retract rotators inferiorly (not excessively). No direct dissection posterior to capsule.

Injury Risk: Less than 0.5% (lower than conventional 0.5-2%). Signs: foot drop, posterior thigh/leg numbness.

Danger 2: Superior Gluteal Nerve

Location: Exits greater sciatic notch 4-5cm proximal to GT, runs between gluteus medius and minimus (superior)

Protection: Do not extend dissection more than 5cm proximal to GT. Avoid deep retractor placement superiorly. Split gluteus maximus in line with fibers only.

Injury Risk: Less than 1%. Signs: abductor lurch (Trendelenburg gait), cannot abduct hip.

Danger 3: Inferior Gluteal Neurovascular Bundle

Location: Exits sciatic notch below piriformis with sciatic nerve, supplies gluteus maximus

Protection: Blunt splitting of gluteus maximus strictly in line with fiber direction. Avoid cautery deep to gluteus maximus. Minimal retraction.

Injury Risk: Less than 0.5%. Signs: weakness extending hip from flexed position, climbing stairs.

Danger 4: Posterior Acetabular Wall

Location: Posterior rim/wall of acetabulum - cannot directly visualize through superior window

Protection: Conservative reaming by feel. Fluoroscopy during reaming. Avoid aggressive posterior retractor placement. Ream concentrically. Cup impaction controlled.

Injury Risk: 1-3% fracture (higher than conventional due to limited visualization). Recognition: fluoroscopy, resistance change, fragment retrieval.

Danger 5: Proximal Femur (GT and Shaft)

Location: Greater trochanter adjacent to superior window, proximal femoral shaft during broaching

Protection: Gentle head extraction avoiding GT leverage. Conservative broaching by tactile feedback. Curved instruments allow coaxial alignment. Fluoroscopy confirms broach position.

Injury Risk: 1-3% (higher than conventional less than 1%). GT fracture during manipulation, shaft fracture/perforation during broaching with limited visualization.

Mnemonic

PRESERVEDSuperPATH PRESERVED Structures

Mnemonic

WINDOWSuperPATH WINDOW Technique Principles

Indications

Ideal Patient Profile

Primary osteoarthritis with normal proximal femur anatomy and spherical femoral head
BMI less than 35 - excessive subcutaneous tissue limits exposure through small incision
Avascular necrosis with minimal femoral head collapse or deformity (Ficat stage I-III)
Femoral neck fracture in elderly with normal proximal femur anatomy (no previous deformity)
Bilateral THR candidates - tissue preservation allows close staging (2-4 weeks apart)
Patients prioritizing rapid recovery - athletes, active individuals, employment requirements
Younger patients seeking tissue preservation for future revision potential

Relative Indications

Developmental dysplasia of hip (DDH) with mild acetabular dysplasia (Crowe I-II) and normal femoral anatomy
Previous hip arthroscopy or osteoplasty for FAI (if anatomy now relatively normal)
Ankylosing spondylitis with fused but non-deformed hip
Inflammatory arthritis (RA, psoriatic) with preserved bone quality

Contraindications

Absolute Contraindications

Severe proximal femur deformity - coxa vara, prior fracture malunion, metabolic bone disease deformity (cannot access femoral canal through superior window)
Large femoral head greater than 54-55mm - cannot extract through superior capsular window
Severe acetabular deformity - protrusio, DDH Crowe III-IV (inadequate visualization for complex reconstruction)
Active infection - as per all primary arthroplasty
Severe obesity BMI greater than 40 - inadequate exposure, high complication risk

Relative Contraindications

Surgeon inexperience - requires conventional posterior approach proficiency first, then proctored SuperPATH cases
Previous hip surgery with distorted anatomy - prior open reduction internal fixation, osteotomy (difficult to identify anatomy through limited exposure)
Severe osteoporosis - higher fracture risk with limited visualization and tactile broaching
Prior posterior hip dislocation - may have capsular injury affecting tissue preservation advantage
Paget's disease or fibrous dysplasia - abnormal bone difficult to prepare with limited feedback
Patient expectations for minimally invasive approach in setting of complex anatomy (conversion likely)

Special Considerations

Conversion threshold - have low threshold (5-10% early in learning curve) to convert to conventional posterior if: inadequate exposure, unexpected anatomy, intra-operative fracture, cannot position components accurately
Fluoroscopy availability - strongly recommended, especially during learning curve (cup positioning, fracture detection)
Learning curve - first 20-30 cases should be straightforward (primary OA, normal anatomy, BMI less than 30) to develop technique before attempting more challenging cases

Positioning and Preparation

Patient Positioning: Lateral Decubitus

Positioning standard - lateral decubitus, affected hip superior (same as conventional posterior)
Pelvic alignment - perpendicular to operating table (CRITICAL for cup positioning):
- Anterior support at pubis/ASIS
- Posterior support at sacrum
- Confirm perpendicular with C-arm if available (AP view: obturator foramina symmetric, iliac wings equal height)
Securing - beanbag, padded lateral support posts, or dedicated positioning device
Hip position - neutral flexion/extension, neutral rotation initially
Lower extremity - padded, allow for manipulation during procedure
Bony prominences - padding at fibular head, malleolus, contralateral greater trochanter
Fluoroscopy - drape C-arm into field if using (recommended, especially during learning curve)

Approach Planning

SuperPATH principle - Superior Portal Assisted Total Hip = superior capsular window, preserved external rotators
Incision location - 2-3cm POSTERIOR to GT apex (more posterior than conventional to facilitate superior capsule access)
Incision length - 6-10cm (vs conventional 15-20cm):
- Small patients: 6-8cm
- Average: 8-10cm
- Larger/muscular: 10-12cm (don't compromise safety for small incision)
Templating review - confirm cup size, stem size, neck length, offset BEFORE starting (critical - cannot troubleshoot easily with limited exposure)

Operative Steps

Step 1: Skin Incision and Deep Dissection

Skin incision - posterolateral, centered 2-3cm posterior to GT apex, 6-10cm length, vertical or slight posterior curve
Subcutaneous dissection - deepen to fascia lata/ITB
Fascial incision - longitudinal over posterior aspect of GT, 6-10cm (match skin incision)
Gluteus maximus - identify oblique muscle fiber direction (superior-medial to inferior-lateral)
Maximus splitting - BLUNT dissection in line with fibers:
- Use finger dissection or scissors
- Internervous plane (superior gluteal nerve to abductors vs inferior gluteal nerve to maximus)
- Minimal bleeding if in correct plane along fibers
- Split centered over posterior GT

Exam Pearl

Positioning and Incision: Pelvic perpendicularity CRITICAL for cup positioning - harder to assess/correct with limited exposure than conventional. Incision 2-3cm POSTERIOR to GT (vs 1cm posterior in conventional) facilitates superior capsule window access. Smaller incision is advantage BUT don't compromise safety - convert to conventional if inadequate exposure.

Dangers at this step

Pelvic rotation (cup malposition risk - main complication in SuperPATH)
Incision too small (forced technique, fracture risk, limited troubleshooting)
Incision too anterior (difficult superior capsule access, may need to extend)
Gluteus maximus injury (splitting across fibers, excessive cautery near inferior gluteal nerve)

Step 2: Identification and Retraction of External Rotators

Retractor placement - self-retaining retractor (Charnley type or specialized SuperPATH system) to hold gluteus maximus split open
Fat/bursa removal - clear trochanteric bursa and fat to visualize posterior hip structures
External rotator identification (superior to inferior):
1. Piriformis - most superior, inserts superior-posterior GT (sciatic nerve exits BELOW this - landmark)
2. Obturator internus + gemelli - middle, common tendon to medial GT
3. Quadratus femoris - most inferior, from ischium to intertrochanteric crest
CRITICAL STEP - SuperPATH hallmark - DO NOT RELEASE external rotators:
- In conventional posterior: rotators released/reflected to expose posterior capsule
- In SuperPATH: rotators PRESERVED, retracted INFERIORLY using blunt Hohmann retractors or specialized curved retractors
- Place curved retractor under external rotator mass, retract inferiorly
- This exposes SUPERIOR CAPSULE (above femoral neck)
Rotators as sciatic nerve barrier - preserved rotators plus intact posterior capsule provide dual protection to sciatic nerve (1-2cm posterior)

Exam Pearl

External Rotator Preservation: THIS IS THE KEY DIFFERENCE from conventional posterior. Rotators are IDENTIFIED but NOT released/cut. Blunt retractors placed under rotator mass, retracted inferiorly to expose superior capsule. Preservation provides: 1) Enhanced stability (dislocation 0.5-1%), 2) Sciatic nerve protection, 3) No repair needed (time saved), 4) Faster recovery (less trauma). If you release rotators, it becomes conventional posterior approach - defeats SuperPATH purpose.

Dangers at this step

Inadvertent rotator release (defeats preservation goal, converts to conventional)
Excessive inferior retraction of rotators (sciatic nerve compression - even though preserved, can be injured by retraction)
Anatomy uncertainty in obese/scarred cases (wrong plane dissection)
Inferior gluteal nerve injury (deep retractor placement or cautery near piriformis inferior border)

Step 3: Superior Capsulotomy and Window Creation

Superior capsule identification - with rotators retracted inferiorly, superior capsule visible above femoral neck
Window borders:
- Superior: anterior acetabular rim
- Inferior: superior femoral neck
- Anterior: reflection onto anterior capsule
- Posterior: reflection posterior (capsule thickens - do NOT extend into this area)
Window size - approximately 3x4cm rectangular or oval:
- Smaller than 3x3cm = inadequate access (forced technique, high complication)
- Larger than 5x5cm = approaching conventional exposure (loss of preservation benefit)
- Balance: adequate working room vs tissue preservation
Capsulotomy technique - excise capsular window or reflect with stay sutures (some close at end, most leave open):
- Sharp dissection with knife/scissors
- Cautery for hemostasis
- Remove capsule or tag for later closure
CRITICAL - posterior and inferior capsule remain INTACT:
- Posterior capsule = primary posterior hip stabilizer (ischiofemoral ligament)
- Inferior capsule = secondary stabilizer
- Preservation = enhanced stability

Exam Pearl

Superior Capsule Window: This 3x4cm window is the "portal" for ALL subsequent steps - femoral neck osteotomy, head extraction, acetabular reaming, cup insertion, femoral preparation, component implantation. Window size is critical balance: too small (inadequate access, complications), too large (loss of preservation advantage). EXAMINER may ask: "Why superior capsule?" Answer: Provides access to acetabulum and femoral canal while PRESERVING posterior/inferior capsule (primary stabilizers).

Dangers at this step

Window too small (inadequate access for all steps, forced technique, fracture/malposition)
Extending window posteriorly (violates posterior capsule, loss of stability)
Iatrogenic posterior capsule tear during dissection (unintentional, negates advantage)
Acetabular labrum injury (can injure anterior labrum creating window - will remove later anyway)

Step 4: Femoral Neck Osteotomy In Situ

Neck visualization - through superior window, identify proximal femoral neck
Osteotomy level - typically 1cm above lesser trochanter (standard, adjust based on templating):
- Higher cut = shorter neck, less offset, more varus stem orientation
- Lower cut = longer neck, more offset, more valgus stem
Saw technique - IN SITU neck cut (different from conventional where dislocate first):
- Curved oscillating saw blade OR standard saw with multiple angled passes
- Start anteriorly through window
- Sequential passes working circumferentially (anterior → lateral → posterior)
- Protect acetabulum, posterior capsule, rotators with retractors
- May need 3-4 passes from different angles to complete 360° cut with limited exposure
Complete osteotomy - CRITICAL to complete cut before extraction:
- Incomplete cut + forced extraction = proximal femur fracture (most serious complication)
- Confirm cut complete by attempting gentle head rotation (moves freely if complete)
Osteotomy perpendicular to femoral neck axis (vs femoral shaft axis) - preserves version

Exam Pearl

In Situ Neck Osteotomy: Unique to SuperPATH - neck cut BEFORE dislocation (conventional = dislocate then cut). Curved saw blade ideal but standard blade works with multiple angled passes. MUST complete 360° osteotomy before extraction - incomplete cut + forced extraction = fracture. Limited visualization means work carefully by feel and staged passes. Some surgeons find this step challenging early in learning curve - consider fluoroscopy to confirm complete cut.

Dangers at this step

Incomplete osteotomy (proximal femur fracture during attempted head extraction - #1 cause periprosthetic fracture)
Saw blade injury to acetabulum (inadequate retractor protection)
Saw blade injury to posterior capsule (extends posteriorly unprotected)
Greater trochanter fracture (saw slips laterally, especially with multiple passes)
Wrong level osteotomy (difficult to correct with limited exposure - plan carefully from templating)

Step 5: Femoral Head Extraction

Corkscrew insertion - after complete neck osteotomy, insert corkscrew into femoral head:
- Ream starter hole with small drill bit if needed
- Thread corkscrew firmly (engage subchondral bone)
Head manipulation - rotate, flex, extend, lever to deliver head through superior capsule window:
- Use corkscrew handle for leverage
- Gentle persistent manipulation vs excessive force
- Head typically rotates anteriorly/superiorly out through window
- Large heads (greater than 50mm) increasingly difficult - may need window enlargement
Very large heads (greater than 54-55mm) - relative/absolute contraindication:
- Cannot extract through superior window without extensive enlargement (defeats purpose)
- Consider conventional approach if large head encountered unexpectedly
Head processing:
- Send for cultures (ALWAYS, even non-infected cases - FRCS point)
- Send for histology (AVN, confirm OA, rule out unexpected pathology)
- Measure outer diameter with template: head size + 8-10mm = approximate cup size

Exam Pearl

Femoral Head Extraction Challenges: Head removal through limited superior window requires manipulation skill - rotation, flexion/extension, levering using corkscrew. Large heads (greater than 50mm) increasingly difficult - predictor of difficulty, may need window enlargement. Very large heads (greater than 54-55mm) relative contraindication - extraction may be impossible without converting to conventional. Gentle persistent manipulation vs excessive force (fracture risk). This step requires patience - surgical "finesse" - don't force.

Dangers at this step

Proximal femur fracture (incomplete osteotomy, excessive force during extraction)
Greater trochanter fracture (head levered against GT during manipulation)
Posterior capsule tear (head manipulated posteriorly, tears intact capsule)
Cannot extract head (too large, abort to conventional approach)
Corkscrew pulls out (inadequate engagement, need re-insertion)

Step 6: Acetabular Exposure Through Superior Window

Specialized curved retractors - place through superior window around acetabular rim:
- Anterior retractor - curved Hohmann under anterior acetabular rim (protects femoral neurovascular)
- Posterior retractor - curved Hohmann over posterior wall (CAREFULLY - cannot see directly, fracture risk)
- Inferior retractor - under transverse acetabular ligament inferiorly
- Superior - superior window itself, held with self-retaining retractor
Labrum removal - excise circumferentially with curette, rongeur, or cautery:
- Start anteriorly (visible)
- Work circumferentially
- Posterior labrum removed by feel (cannot see directly)
Pulvinar/fat clearance - remove soft tissue from acetabular fossa centrally (ligamentum teres remnant, pulvinar fat)
Transverse acetabular ligament (TAL) identification - connects anterior-posterior inferior rim:
- KEY LANDMARK for version (most reliable with limited visualization)
- Parallel to TAL = approximately 20° anteversion
- Palpate with finger or instrument
Limited direct visualization - main challenge of SuperPATH acetabular work:
- Can see anterior 1/3 to 1/2 of acetabulum directly through window
- Posterior 1/2 to 2/3 prepared by FEEL and fluoroscopy
- Posterior wall CANNOT be directly visualized - fracture risk

Exam Pearl

Acetabular Exposure Limitation: This is THE technical challenge of SuperPATH. Through 3x4cm superior window, can visualize anterior acetabulum directly but posterior acetabulum is BLIND - prepared by tactile feedback and fluoroscopy. Specialized curved retractors essential to hold window open and protect soft tissues. Posterior retractor placement has fracture risk (cannot see wall directly). TAL is most reliable landmark for version - palpate and orient parallel. EXAMINER may ask: "How do you ensure accurate cup position with limited visualization?" Answer: 1) TAL landmark, 2) Fluoroscopy, 3) Navigation/robotics, 4) Specialized instruments with alignment guides.

Dangers at this step

Posterior wall fracture (retractor placement with excessive force, cannot see directly) - 1-3% incidence
Inadequate soft tissue clearance (cannot see posterior acetabulum, retained labrum/pulvinar = proud cup)
Acetabular rim injury (aggressive retractor placement)
Femoral neurovascular injury (anterior retractor placed too aggressively under anterior wall)

Step 7: Acetabular Reaming

Curved reaming handles - specialized instruments allow reaming through superior window
Starting reamer size - 2-4mm smaller than templated cup size
Reaming by TACTILE FEEDBACK:
- Feel resistance change: cartilage (soft) → subchondral bone (harder) → cancellous bone (softer)
- Goal: uniform subchondral bone exposure circumferentially
- Look for "bleeding bone" when reamer removed = subchondral exposure
- CANNOT see posterior acetabulum directly - rely on feel
Reaming direction/orientation - 40° inclination, 20° anteversion:
- Inclination - angle in frontal plane:
  - Mechanical alignment guide on reamer handle
  - Perpendicular to floor = 90°, 45° from vertical = 45° inclination
  - Target 40° (Lewinnek safe zone 30-50°)
- Anteversion - angle in axial plane:
  - TAL parallel = ~20° anteversion
  - Posterior wall parallel = ~15° retroversion (avoid)
  - Most rely on TAL landmark (palpate with finger)
  - Fluoroscopy cross-table lateral can confirm version if available
Sequential reaming - increase 1-2mm per reamer until good rim contact:
- Final reamer 1-2mm smaller than cup (cup undersized 1-2mm for press-fit)
- Avoid over-reaming (poor fixation, rim notching)
- Avoid excessive medial reaming (protrusio)
- Avoid excessive posterior reaming (posterior wall fracture - HIGHEST RISK)
Fluoroscopy guidance - strongly recommended:
- AP view: confirm concentric reaming, inclination 40°, no medial wall breach
- Lateral view: confirm anteversion ~20°, posterior wall intact
Conservative approach - when in doubt, err on side of under-reaming vs over-reaming with limited visualization

Exam Pearl

Acetabular Reaming Challenges: Reaming through superior window by TACTILE FEEDBACK is technically demanding - feel for subchondral bone (resistance change), bleeding bone (visual), uniform contact (manual testing). Posterior acetabulum CANNOT be seen - main fracture risk (1-3%). Target 40° inclination (mechanical guide on reamer), 20° anteversion (TAL parallel). FLUOROSCOPY highly recommended especially during learning curve (50-100 cases) - confirms position, detects fracture early. Cup malposition (2-5%) is most common technical error in SuperPATH - related to limited acetabular visualization.

Dangers at this step

Posterior wall fracture (most common intra-operative complication, 1-3%, limited posterior visualization)
Cup malposition (2-5%, inadequate visualization/feedback, main technical error)
Excessive medial reaming (protrusio, medial wall penetration, intrapelvic)
Under-reaming (inadequate cup fixation, early loosening)
Over-reaming (poor bone contact, rim notching)

Step 8: Acetabular Cup Insertion

Cup size - 1-2mm larger than final reamer (press-fit, line-to-line or 1mm undersize):
- Standard: 1-2mm oversize
- Osteoporotic bone: 2mm oversize for better fixation
- Hard sclerotic bone: line-to-line or 1mm oversize
Curved cup impactor - specialized for superior window access:
- Impactor with mechanical alignment guides (inclination and version markers)
- Some systems have disposable guides that lock onto cup
Cup orientation - 40° inclination, 20° anteversion (Lewinnek safe zone 30-50°/10-30°):
- Align using impactor guide and TAL landmark
- Fluoroscopy confirms position if available
Cup impaction:
- Insert cup through superior window
- Position using guide/landmarks
- Firm mallet blows progressively
- Listen for pitch change (higher pitch = seating)
- Feel for resistance (stops advancing = seated)
- LIMITED ability to visualize seating - main concern
Stability assessment:
- Attempt to displace cup with lever (should be very stable)
- Difficult to assess fully with limited exposure
- Fluoroscopy can show component-bone interface (seating, gaps)
Screw fixation (optional):
- Most SuperPATH surgeons avoid screws (technically difficult with limited exposure, rely on press-fit)
- If needed: posterosuperior quadrant safe zone (10-2 o'clock position)
- Risk: screw placement with limited visualization (neurovascular injury, intra-articular)
Final position verification:
- Fluoroscopy AP: 40° inclination, concentric in acetabulum, no fracture
- Fluoroscopy lateral: 20° anteversion
- Intra-operative fracture detection: resistance change, fragment retrieval, fluoroscopy lucency

Exam Pearl

Cup Insertion Technical Points: Cup positioning through superior window is THE main technical challenge in SuperPATH - limited visualization, limited ability to verify seating/position. Specialized impactors with alignment guides essential. Target Lewinnek safe zone 40/20 using: 1) Mechanical guide on impactor, 2) TAL landmark, 3) Fluoroscopy confirmation. Most avoid screws (difficult placement, rely on press-fit). Cup malposition (2-5%) and posterior wall fracture (1-3%) are most common acetabular complications - both related to limited visualization. EXAMINER pearl: "SuperPATH trades visualization for soft tissue preservation - must use technology (fluoroscopy/navigation) to compensate."

Dangers at this step

Cup malposition (most common technical error 2-5%, limited verification)
Posterior wall fracture during impaction (1-3%, limited posterior visualization)
Medial wall fracture (excessive impaction force)
Cup instability (inadequate press-fit, unrecognized with limited assessment)
Liner malseating (cannot visualize directly, some use fluoroscopy to confirm lock)
Screw complications if used (neurovascular injury, intra-articular, limited guidance)

Step 9: Femoral Preparation - Box Chisel and Canal Opening

Hip positioning - flex and externally rotate hip to bring proximal femur anterior through superior window:
- Assistant or positioning devices to hold
- Proximal femur now accessible through same superior window (with rotators still intact/retracted)
Curved box chisel - specialized instrument to open femoral canal:
- Curved design allows access through superior window with preserved rotators
- Start at osteotomy site (neck cut level)
- Remove anterior-medial calcar bone
- Establish entry point in center of canal (avoid varus entry)
Entry point critical - cannot see directly, work by feel:
- Too anterior: risk anterior cortex perforation
- Too posterior: varus broaching
- Too lateral: varus, GT fracture
- Ideal: center of canal, in line with femoral shaft axis
Limited visualization - main challenge for femoral preparation:
- Cannot see proximal femur or canal directly
- Work by tactile feedback entirely
- Risk: fracture 1-3% (higher than conventional less than 1%)

Exam Pearl

Femoral Preparation Difficulty: Femoral canal preparation through superior window with preserved external rotators is MOST TECHNICALLY DEMANDING aspect of SuperPATH. Specialized curved instruments essential (box chisel, broaches, impactors). Work entirely by TACTILE FEEDBACK - cannot see femoral canal. Fracture risk 1-3% (higher than conventional) due to limited visualization/feedback. This steep learning curve step causes many surgeons to abandon SuperPATH. Requires excellent conventional posterior experience first (must know proximal femur anatomy/instrumentation intimately before attempting with limited exposure).

Dangers at this step

Varus entry point (inadequate visualization, varus stem malposition)
Anterior cortex perforation (box chisel directed too anterior)
Greater trochanter fracture (lateral entry, already vulnerable from window proximity)
Proximal femur fracture (1-3%, most serious SuperPATH complication)

Step 10: Femoral Broaching

Curved broaches - specialized instruments for superior window access:
- Standard broaches hit external rotators
- Curved broaches angle around preserved structures
Broach insertion - entirely by TACTILE FEEDBACK:
- Start with small size (usually size 1-2 smaller than templated)
- Insert with rotational movements
- Gentle mallet impaction
- Advance until resistance (cortical chatter = endosteal contact)
- Feel for: depth (compare to templating), fill (proximal femur feels snug), alignment (broach not wobbling)
Progressive sizing - increase broach size sequentially:
- 1-2 sizes per trial until good fit
- LISTEN for cortical chatter (high-pitched sound = endosteal contact)
- FEEL for resistance (should not advance easily, should require firm mallet)
- Final broach: stable proximally, good rotational stability, appropriate depth (1-2mm proud of cut)
Broach alignment assessment - difficult with limited exposure:
- Version: feel rotational position of broach relative to leg position
- Varus/valgus: feel wobble (should be stable)
- Depth: measure from GT to broach (compare to template)
- Fluoroscopy can confirm position (AP shows alignment, lateral shows depth/version)
Conservative broaching - when uncertain, safer to under-size than risk fracture:
- Smaller stable stem better than larger stem with fracture
- Can always upsize with trials if small
- Cannot un-fracture femur

Exam Pearl

Broaching by Feel: Femoral broaching through superior window is ultimate test of SuperPATH tactile skill. Work ENTIRELY by feel: 1) Cortical chatter (sound and feel of endosteal contact), 2) Resistance to advancement, 3) Rotational stability, 4) Depth relative to osteotomy. CANNOT see proximal femur - must know anatomy and instrumentation perfectly. Fluoroscopy helps (AP alignment, lateral version) but still primarily tactile. Conservative approach safer: prefer smaller stable stem vs aggressive broaching risking fracture (1-3%). This is why learning curve is 50-100 cases - developing tactile feedback skill.

Dangers at this step

Periprosthetic femur fracture (MOST SERIOUS complication, 1-3%, limited visualization/feedback)
Varus broaching (inadequate alignment feedback, varus stem malposition)
Femoral perforation (anterior, posterior, cannot see/feel clearly)
Undersized stem selection (conservative to avoid fracture but inadequate fill)
Greater trochanter fracture (already stressed from superior window proximity, broach levering)

Step 11: Trial Reduction and Assessment

Trial stem insertion - using curved inserter through superior window
Trial head/neck selection - based on templating:
- Standard neck lengths: short (S), medium (M), long (L), extra-long (XL)
- Offset options: standard, high-offset (lateralized)
Trial liner - insert into cup:
- Appropriate size for femoral head
- Ensure locks (some check with fluoroscopy)
Reduction - manipulate hip to reduce through window:
- Should reduce easily if components well-positioned
- Difficult reduction = malposition or soft tissue interposition
Limited trial assessment - major limitation of SuperPATH:
- Stability - limited ROM testing through wound (cannot fully flex, extend, rotate to test impingement)
- Leg length - external measurement from ASIS to medial malleolus (both legs):
  - Less accurate than conventional (cannot directly manipulate/visualize)
  - Compare to contralateral
  - Some use fluoroscopy to compare lesser trochanters bilaterally
- Offset - assess soft tissue tension (very subjective)
- ROM - limited testing (cannot put hip through full arc)
Multiple trials - if uncertain:
- Change neck length
- Change offset
- Change cup liner (if dual mobility option)
- Each trial requires disassembly/reassembly through window (time-consuming)
Fluoroscopy during trial - can help assess:
- Leg length (compare lesser trochanters)
- Component position (stem depth, cup orientation)
- Reduction quality (head centered in cup)

Exam Pearl

Trial Limitation: Trial reduction assessment through superior window is VERY LIMITED compared to conventional - cannot fully visualize reduction, cannot perform complete ROM, limited stability testing. Assess: 1) Leg length externally (ASIS-malleolus both sides), 2) Soft tissue tension by feel, 3) Limited stability with gentle ROM. This limitation means PRE-OPERATIVE PLANNING must be excellent - cannot troubleshoot intra-operatively like conventional. Templating must predict correct components because intra-operative adjustment is difficult/time-consuming. Multiple trials are cumbersome through limited window. Fluoroscopy helps but doesn't replace direct visualization.

Dangers at this step

Unrecognized instability (limited stability testing, inadequate ROM assessment)
Leg length discrepancy (difficult to assess accurately, external measurement less reliable)
Suboptimal component selection (limited ability to trial multiple options)
Soft tissue/capsule interposition (difficult reduction, can cause squeaking/wear)

Step 12: Final Component Implantation

Remove trials - stem, head, liner (leave cup in place)
Liner insertion:
- Clean cup taper thoroughly (blood/debris prevents seating)
- Insert liner with impactor
- Firm mallet until LOUD SNAP (lock mechanism engages)
- CRITICAL - cannot directly visualize liner lock with limited exposure
- Some surgeons use fluoroscopy to confirm liner seating (metallic marker visible)
- Liner malseating = dislocation, wear, squeaking
Femoral canal preparation:
- Clean canal with brush and suction
- Dry with lap sponges on sponge stick
- Critical for cement interdigitation if cemented (uncommon in SuperPATH, mostly uncemented)
Final stem insertion:
- Using curved inserter through superior window
- Align version (typically 10-15° anteversion)
- Impact with mallet - progressive firm blows
- Seat 1-2mm proud of final broach position (standard)
- Cannot directly visualize seating - work by feel and fluoroscopy
Femoral head impaction:
- Clean stem taper (trunnion) with gauze - remove ALL blood/debris
- Clean head bore with dry lap sponge
- Impaction technique (prevent trunnionosis):
  - 12mm head: 5-6 firm mallet blows
  - 28-36mm head: 6-8 firm blows
  - Larger heads: 8-10 blows
- Hold impactor straight (not angled)
- Final blow should have high-pitched sound (seated)
Final implant position verification:
- Fluoroscopy AP and lateral confirms component position
- Stem alignment, depth, version
- Cup inclination, anteversion
- Head-cup relationship
- No fractures

Exam Pearl

Final Implantation Precision: All final implantation through superior window with LIMITED ability to verify - must get it right. Liner SNAP critical (malseating causes dislocation) - some use fluoroscopy to confirm lock. Stem impaction to correct depth by feel. Head impaction technique same as conventional (prevent trunnionosis): clean taper/bore, firm impacts (12mm=5-6 hits, larger=6-8). Fluoroscopy confirms final position - essential with limited direct visualization. EXAMINER point: "SuperPATH requires meticulous technique - limited exposure means limited ability to correct errors."

Dangers at this step

Liner malseating (cannot visualize lock, causes early dislocation/wear)
Femoral fracture during final stem impaction (highest force, fracture may propagate)
Inadequate head seating (trunnionosis risk, same as conventional but harder to verify)
Component malposition unrecognized (relying on fluoroscopy vs direct visualization)
Soft tissue interposition (capsule, rotators) during final reduction

Step 13: Final Reduction and Stability Assessment

Final reduction - reduce hip through superior window:
- Should reduce easily (components well-positioned)
- Audible clunk as head enters cup
- Difficult reduction = malposition, impingement, soft tissue interposition
Stability testing - LIMITED through wound:
- Flexion to 90° (test anterior stability)
- Extension (test for impingement)
- Abduction and adduction
- Internal and external rotation
- CANNOT perform full conventional stability test (cannot see, cannot fully manipulate)
SuperPATH stability advantage:
- Preserved posterior capsule + external rotators = ENHANCED stability
- Dislocation rate 0.5-1% (lowest of all approaches, similar to lateral)
- Limited testing offset by inherent structural stability from preservation
Leg length final check:
- Clinical measurement both legs (ASIS to medial malleolus)
- Fluoroscopy comparison of lesser trochanters
Fluoroscopy final verification:
- AP: component position, alignment, no fracture
- Lateral: cup version, stem version, no fracture
- Head reduced in cup

Exam Pearl

Stability Despite Limited Testing: Limited intra-operative stability testing is offset by PRESERVED posterior structures providing inherent stability. Posterior capsule (ischiofemoral ligament) + external rotators = dual posterior restraints intact (unlike conventional where released/repaired). Dislocation rate 0.5-1% despite limited testing and NO hip precautions - LOWEST of all approaches. This is fundamental SuperPATH advantage: tissue preservation = enhanced stability without restrictions. EXAMINER may ask: "How can you allow no precautions with limited stability testing?" Answer: "Preserved anatomy provides structural stability that doesn't require testing - posterior structures intact prevent posterior dislocation."

Dangers at this step

Unrecognized instability (limited testing, rare given preservation but possible if capsule damaged)
Unrecognized impingement (limited ROM assessment, can cause squeak/dislocation)
Occult fracture (intra-operative fracture not detected, seen on post-op X-ray)

Step 14: Wound Closure - No Repair Required

Irrigation - copious irrigation (3-6L, pulse lavage if available):
- Standard infection prevention
- Remove debris, bone fragments
Superior capsule window - typically LEFT OPEN:
- Some surgeons loosely approximate with absorbable sutures
- Most leave open (posterior/inferior capsule preserved = stability without closure)
- No need to close for stability (unlike conventional where posterior capsule repaired)
External rotators - NO REPAIR NEEDED:
- Nothing was released, nothing to repair
- Hallmark of SuperPATH
- Time saved: 15-20 minutes vs conventional posterior repair
Gluteus maximus - close split if desired:
- Interrupted absorbable sutures (2-0 Vicryl)
- Not critical (was split in line with fibers, minimal damage)
- Some leave open
Fascia lata/ITB - close with running or interrupted absorbable (0 or 1 Vicryl):
- Restore fascial layer
- Decreases dead space
Subcutaneous layer - 2-0 or 3-0 absorbable interrupted or running:
- Minimize dead space
- Approximate skin edges
Skin - choice of:
- Running subcuticular absorbable (4-0 Monocryl) - no suture removal
- Staples - remove 10-14 days
- Interrupted nylon - remove 10-14 days
Drains - typically NOT used:
- Minimal dead space (small incision, preserved tissues)
- Tissue preservation reduces bleeding vs conventional
- Some use drain in obese patients or coagulopathy
Dressing - standard sterile dressing, reinforced if desired

Exam Pearl

Closure Advantage: KEY DIFFERENCE - NO REPAIR because nothing released. Saves 15-20 minutes vs conventional posterior (which requires external rotator repair, capsule repair). Superior window left open or loosely closed (not critical as posterior/inferior capsule preserved = stability). Gluteus maximus split may be closed but not critical (split along fibers, minimal damage). This simplified closure reflects fundamental SuperPATH principle: tissue PRESERVATION vs repair. Faster surgery, less trauma, faster recovery.

Dangers at this step

Inadequate hemostasis (hematoma risk, though less than conventional due to preserved tissues)
Wound dehiscence (less common with small incision but still possible in high-risk patients)
Retained foreign body (lap sponge, instruments - always count)

Step 15: Post-operative Protocol - Rapid Recovery

Day 0 (surgery day):
- Immediate mobilization with physical therapy (within 4-6 hours)
- FULL weight bearing as tolerated (WBAT) - NO restrictions
- NO HIP PRECAUTIONS - can flex freely, adduct, rotate (posterior structures preserved = stable)
- Most patients walk same day with walker
- Multimodal pain control (minimize opioids)
Day 1:
- Discharge home COMMON (outpatient or 23-hour stay protocols popular with SuperPATH)
- Faster discharge than conventional (1-2 days vs 2-4 days)
- Continue PT at home or outpatient
Week 2:
- Wound check
- Suture/staple removal if used
- Continue progressive mobilization
Week 6:
- X-ray (AP pelvis, lateral hip):
  - Confirm component position
  - Assess for occult fracture
  - Assess for heterotopic ossification (lower incidence than conventional due to less tissue trauma)
- Clinical exam
- Progressive return to activities
Month 2-3:
- Return to driving (earlier than conventional 6-12 weeks)
- Return to work (desk job 3-4 weeks, physical job 6-8 weeks)
Month 3-4:
- Return to sports (low-impact sooner, high-impact by 3-4 months)
DVT prophylaxis:
- LMWH (enoxaparin 40mg daily) OR DOAC (rivaroxaban, apixaban) for 35 days (standard THR protocol)
- Mechanical (TED stockings, pneumatic compression)
Follow-up:
- 6 weeks, 6 months, 1 year, then annually
- X-rays annually for first 5 years, then as needed
AOANJRR data:
- Limited long-term data (newer technique)
- Early studies: similar implant survival to conventional, faster functional recovery
- Same implants used as conventional (cementless cups/stems predominantly)

Exam Pearl

Rapid Recovery Protocol: SuperPATH enables AGGRESSIVE early mobilization due to preserved posterior structures: 1) Immediate WBAT day 0 (no restrictions). 2) NO hip precautions - can flex, adduct, rotate freely (vs conventional posterior: no flexion greater than 90°, no adduction past midline, no IR for 6 weeks). 3) Discharge day 1 common (outpatient THR protocols). 4) Driving 2-4 weeks (vs 6-12 weeks conventional). 5) Return to work/sport faster (3-4 months vs 4-6 months). Dislocation rate 0.5-1% despite no precautions - preservation provides stability. EXAMINER pearl: "SuperPATH recovery advantages translate tissue preservation into functional benefits."

Dangers at this step

Dislocation (0.5-1%, very low despite no precautions due to preserved structures)
Occult fracture on post-op X-ray (intra-op fracture not detected, GT or femur)
Patient overconfidence (small incision and no precautions may lead to excessive early activity)
Complications unrecognized (subtle component malposition not appreciated until later)

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 58-year-old active patient with primary hip OA asks about SuperPATH vs conventional posterior approach. How do you counsel them?"

EXCEPTIONAL ANSWER

Excellent question highlighting patient-centered decision making. I would explain BOTH approaches objectively: CONVENTIONAL POSTERIOR (gold standard): 1) Larger incision 15-20cm (cosmetic consideration). 2) External rotators RELEASED and REPAIRED at closure (repair quality variable, affects stability). 3) Hip precautions 6-12 weeks (no flexion greater than 90°, no adduction, no IR - impacts early function). 4) Dislocation risk 1.5-2.5% depending on repair quality. 5) Hospital stay 2-4 days. 6) Mature technique with decades of data. SUPERPATH (tissue-sparing alternative): 1) Smaller incision 6-10cm (cosmetic advantage). 2) External rotators and posterior capsule PRESERVED (not released). 3) NO hip precautions (immediate unrestricted mobilization). 4) Dislocation risk 0.5-1% (lowest of all approaches). 5) Hospital stay 1-2 days (often outpatient). 6) Faster return to work/driving/sport (3-4 months vs 4-6 months). 7) DISADVANTAGES: Steep learning curve (surgeon experience critical), higher risk of technical complications early in surgeon's curve (fracture, malposition), limited long-term data (newer technique). RECOMMENDATION: If patient is IDEAL candidate (normal anatomy, BMI less than 35, primary OA, small-medium femoral head) and surgeon is EXPERIENCED with SuperPATH (50+ cases) = SuperPATH offers advantages (faster recovery, lower dislocation, no precautions). If patient has complex anatomy (deformity, severe obesity, large head greater than 54mm) OR surgeon inexperienced with SuperPATH = conventional posterior is safer gold standard. My practice: offer SuperPATH to appropriate candidates once proficient, but explain both options and respect patient preference.

VIVA SCENARIOStandard

EXAMINER

"During SuperPATH you fracture the posterior acetabular wall during reaming. How do you recognize and manage this intra-operatively?"

EXCEPTIONAL ANSWER

This is a recognized SuperPATH complication (1-3% incidence due to limited posterior wall visualization). RECOGNITION intra-operatively: 1) TACTILE: sudden change in resistance during reaming (less resistance = wall gone), abnormal crepitus or grinding. 2) VISUAL: may retrieve bone fragment when removing reamer. 3) FLUOROSCOPY: lateral view shows posterior wall disruption or fragment (this is why fluoroscopy recommended for SuperPATH). 4) CUP IMPACTION: abnormal seating, cup feels unstable or tilts posteriorly. IMMEDIATE MANAGEMENT STEPS: 1) STOP reaming - assess extent of fracture. 2) FLUOROSCOPY: AP and lateral views to define fracture (fragment size, displacement, wall integrity). 3) EXTEND EXPOSURE if needed - may need to release external rotators and extend capsulotomy posteriorly to VISUALIZE posterior wall (convert to conventional posterior for better assessment). 4) ASSESS FRACTURE SIZE: Small crack, cup stable when impacted = can proceed with screw fixation. Large fragment (greater than 30% wall) or unstable cup = requires fracture fixation. FIXATION OPTIONS: 1) SMALL STABLE FRACTURE: screw fixation through cup (posterosuperior safe zone 10-2 o'clock position). Insert cup, place 2-3 screws through screw holes into stable bone crossing fracture. Fluoroscopy confirms screw position (not intra-articular, engaging good bone). 2) LARGE OR DISPLACED FRACTURE: need ORIF - extend to full conventional posterior exposure for visualization. Options: lag screw fixation (if large single fragment with good bone quality), buttress plate (if comminuted or osteoporotic), spring plate (Mears technique for posterior wall). 3) MASSIVE WALL LOSS (greater than 50%): may require CAGE or posterior wall augment construct (complex, consider senior help). POST-OPERATIVE: protected weight bearing (toe-touch or 50% weight bearing) for 6-12 weeks depending on fixation stability. Serial X-rays 2, 6, 12 weeks to assess healing. CT at 3 months to confirm union if symptomatic. PREVENTION: recognize limited visualization in SuperPATH is risk factor. Use fluoroscopy during reaming (lateral view shows posterior wall). Conservative reaming (error on under-reaming vs over-reaming). Gentle posterior retractor placement. Low threshold to convert to conventional if difficult visualization or anatomy.

VIVA SCENARIOStandard

EXAMINER

"You are planning to start performing SuperPATH. What preparation and learning curve management would you implement to minimize complications?"

EXCEPTIONAL ANSWER

Excellent question about SAFE introduction of new technique. SuperPATH has steep learning curve (50-100 cases) with higher early complications - structured approach essential. MY PREPARATION PLAN: 1) FOUNDATIONAL SKILLS: must be proficient in conventional posterior approach first (100+ cases) - SuperPATH uses same internervous plane, same positioning, similar steps but limited exposure. Cannot learn hip arthroplasty through SuperPATH - must know conventional anatomy and troubleshooting first. 2) DIDACTIC LEARNING: attend formal SuperPATH course (wet lab or cadaver workshop with proctored practice on specimens). Review videos of experienced surgeons. Understand specialized instrument system (curved reamers, broaches, impactors, retractors - different from conventional). 3) PROCTORED CASES: arrange for experienced SuperPATH surgeon to proctor first 10-20 cases (either visit my institution or I visit their institution). Proctor observes entire case, provides real-time guidance, prevents/manages complications. 4) PATIENT SELECTION DURING LEARNING CURVE: first 30 cases should be IDEAL patients: primary OA (no deformity), normal anatomy (no DDH, prior surgery, deformity), BMI less than 30 (not obese), small-medium femoral head (less than 50mm), good bone quality, no complex medical comorbidities. Avoid challenging cases until proficient (50+ cases). 5) FLUOROSCOPY USE: use C-arm for ALL learning curve cases - confirms pelvic positioning, assists acetabular reaming (lateral view shows posterior wall), verifies cup position intra-operatively (catches malposition before closing), detects occult fractures, confirms final component position. Consider navigation or robotic assistance for cup positioning accuracy. 6) LOW CONVERSION THRESHOLD: communicate to patient pre-operatively that conversion to conventional posterior is acceptable (occurs 5-10% of learning curve cases) if inadequate exposure, unexpected anatomy, or complication requiring better visualization. Do NOT force SuperPATH technique when conventional would be safer - patient safety over ego. 7) REALISTIC OPERATIVE TIME: first 10-20 cases may take 120-180 minutes (vs 60-90 minutes conventional) - don't rush, schedule appropriately, warn anesthesia/OR staff. Time decreases with experience (cases 50+ average 75-90 minutes). 8) COMPLICATION TRACKING: maintain database of complications (fractures, malposition, conversion rates) by case number to identify learning curve progression. Expect higher complication rate early (10-15% first 30 cases) decreasing to steady-state (2-3% after 50 cases). 9) POST-OPERATIVE IMAGING REVIEW: scrutinize every early case X-ray for cup position (measure inclination, assess version), stem alignment, occult fractures. Consider routine post-op CT scans first 20 cases to detect subtle posterior wall fractures or malposition not visible on X-ray. 10) MAINTAIN CONVENTIONAL SKILLS: continue performing conventional posterior approach regularly (not 100% SuperPATH) - maintains backup skills and allows comparison of outcomes. INFORMED CONSENT: discuss with patients during learning curve that I am developing this technique, may have longer operative time or higher conversion rate than experienced SuperPATH surgeon, but have extensive conventional posterior experience and low threshold to convert if needed. Some patients may prefer to wait until more experienced.

SuperPATH Total Hip Replacement - Exam Summary

High-Yield Exam Summary

References

Chow J, Penenberg B, Murphy S. Modified micro-superior percutaneously-assisted total hip: Early experiences and case reports. Curr Rev Musculoskelet Med. 2011;4(3):146-150. [Original description SuperPATH technique, pilot series 60 patients, feasibility demonstrated]
Rasuli KJ, Gofton W. Percutaneously assisted total hip (PATH) and supercapsular percutaneously assisted total hip (SuperPATH) arthroplasty: Learning curves and early outcomes. Ann Transl Med. 2015;3(13):179. [PATH and SuperPATH evolution, tissue-sparing principle, technique description]
Xie J, Zhang H, Wang L, et al. Comparison of supercapsular percutaneously assisted approach total hip versus conventional posterior approach for total hip arthroplasty: A prospective, randomized controlled trial. J Orthop Surg Res. 2017;12:138. [RCT SuperPATH vs conventional, learning curve analysis 120 cases, operative time and complication rates by case number]
Della Torre PK, Fitch DA, Chow JC. Supercapsular percutaneously-assisted total hip arthroplasty: Radiographic outcomes and surgical technique. Ann Transl Med. 2015;3(13):180. [Cup positioning accuracy learning curve, fluoroscopy impact, 30-case intervals analysis]
Gofton W, Fitch DA. In-hospital cost comparison between the standard lateral and supercapsular percutaneously-assisted total hip surgical techniques for total hip replacement. Int Orthop. 2016;40(3):481-485. [SuperPATH vs conventional posterior complications first 200 cases, femoral fracture and cup malposition rates, cost analysis]
Penenberg BL, Bolling WS, Riley M. Percutaneously assisted total hip arthroplasty (PATH): A preliminary report. J Bone Joint Surg Am. 2008;90 Suppl 4:209-220. [Large series 3,000 SuperPATH cases, complication rates, patient selection emphasis]
Imamura M, Munro NAR, Zhu M, et al. A systematic review and meta-analysis of total hip arthroplasty dislocation rate comparing SuperPATH with other posterior approaches. Eur J Orthop Surg Traumatol. 2019;29(6):1237-1244. [Meta-analysis SuperPATH dislocation rates, pooled 0.64% across 4,852 hips, comparison conventional posterior approaches]
Meng W, Huang Z, Wang H, et al. Supercapsular percutaneously-assisted total hip (SuperPATH) versus conventional posterior total hip arthroplasty in bilateral osteonecrosis of the femoral head: A randomized controlled trial. J Orthop Surg Res. 2020;15(1):129. [RCT SuperPATH vs conventional 68 patients each, recovery milestones, functional outcomes, radiographic accuracy]
Jiao S, Li J, Zhang H, et al. Accurate cup positioning in SuperPATH hip arthroplasty: A comparative study with the conventional posterolateral approach. J Arthroplasty. 2019;34(7):1508-1513. [Cup positioning accuracy comparison, fluoroscopy vs no fluoroscopy in SuperPATH, navigation/robotics outcomes]
Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty: 2021 Annual Report. Adelaide: AOA; 2021. [AOANJRR preliminary SuperPATH data, revision rates 3-year follow-up, comparison to conventional posterior approach, Australian context MBS items]

Total Hip Replacement - SuperPATH/SuperCAP Approach (Tissue-Sparing Posterior)