Total Hip Arthroplasty

On this page

THA Basics - Hip Hits Reset

Total Hip Arthroplasty (THA) replaces a damaged hip joint with a prosthesis, aiming for pain relief & function restoration.

Key Indications:

  • Osteoarthritis (OA) - most common
  • Avascular Necrosis (AVN) - femoral head
  • Displaced Neck of Femur Fracture (#NOF) - elderly, active
  • Rheumatoid Arthritis (RA) - severe joint damage
  • Developmental Dysplasia of Hip (DDH) - secondary OA

Contraindications:

  • Absolute:
    • Active sepsis
    • Severe medical comorbidities (prohibitive surgical risk)
  • Relative:
    • Neuromuscular compromise affecting stability
    • Skeletal immaturity
    • Charcot joint (neuroarthropathy)

Pre- and post-op X-rays of bilateral total hip arthroplasty

⭐ Primary osteoarthritis is the most common indication for THA.

THA Blueprint - Plan & Pathways

Pre-operative Evaluation:

  • Hx: Pain, functional limitation. P/E: Harris Hip Score (HHS: <70 Poor, 70-79 Fair, 80-89 Good, 90-100 Excellent), abductor strength (Trendelenburg).
  • Investigations: X-rays (AP Pelvis, Lat Hip), ESR/CRP (infection screen).
  • Medical Fitness: Optimize co-morbidities (cardiac, diabetes).

Templating Goals (Digital/Analog):

  • Restore biomechanical hip center of rotation.
  • Achieve leg length equality.
  • Optimize femoral offset & version for stability.

Surgical Approaches Overview:

  • Posterior (Moore): Most common. Risk: Sciatic n., ↑early dislocation.
  • Lateral (Hardinge): Transgluteal. Risk: Sup. gluteal n., abductor weakness.
  • Anterolateral (Watson-Jones): Interval: TFL & Gluteus Medius.
  • Anterior (DAA): Internervous. Risk: LFCN. Potential faster early recovery.

⭐ The posterior approach is the most commonly used worldwide but carries a higher risk of early dislocation.

Sciatic nerve during posterior approach to hip

THA Hardware - Parts & Performance

  • Components:

    • Acetabular Cup: Ti/Co-Cr alloy; porous coating (uncemented).
    • Liner: UHMWPE, Ceramic; locking mechanism.
    • Femoral Stem: Ti/Co-Cr alloy; designs: tapered wedge, CPT (Collarless Polished Taper).
    • Femoral Head: Ceramic (e.g., Biolox delta), Co-Cr; sizes: 28mm, 32mm, 36mm. Total Hip Arthroplasty Components Exploded View
  • Fixation Methods:

    • Cemented: Polymethylmethacrylate (PMMA). Indications: older patients, poor bone stock, irradiated bone.
    • Uncemented (Press-fit): Relies on bony ingrowth. Indications: younger patients, good bone stock.
  • Bearing Surfaces: Choice impacts wear & longevity.

    SurfaceWear RateProsCons
    Metal-on-Poly (MoP)ModerateCost-effective, historical standardPolyethylene wear, osteolysis
    Ceramic-on-Poly (CoP)Low↓Wear vs MoP, good biocompatibilityHigher cost than MoP
    Ceramic-on-Ceramic (CoC)Lowest↓↓Wear, inert, scratch-resistantRisk of fracture, squeaking, expensive
    Metal-on-Metal (MoM)Variable (Concerns)Allowed large heads; (Largely abandoned)Adverse Reactions to Metal Debris (ARMD), pseudotumors

⭐ Charnley's concept of low-friction arthroplasty revolutionized THA, using a small femoral head (22.225mm) and UHMWPE acetabular component, significantly reducing wear compared to previous designs.

THA Pitfalls & Fixes - Dodging Disasters

  • Intra-op: Femoral/acetabular fracture, Leg Length Discrepancy (LLD), Nerve palsy (sciatic, femoral, sup. gluteal), Vascular injury, Implant malposition.
  • Early Post-op (<6 wks):
    • DVT/PE: Prophylaxis essential.
    • PJI: Dx (MSIS criteria). Class (TSAI/Coventry). Mgmt: DAIR (acute), 1/2-stage revision (chronic).
*   Dislocation: Posterior commonest. Risk factors: surgical approach, component malposition, patient factors. Closed/open reduction.
  • Late Post-op (>6 wks):
    • Aseptic Loosening: Most common late revision cause. Mechanisms: particle-induced osteolysis. Radiographic signs: radiolucent lines, component migration.
    • Osteolysis; Implant wear/failure.
    • Heterotopic Ossification (HO): Risk factors. Prophylaxis (NSAIDs, XRT). Brooker Stages I-IV.
    • Periprosthetic Fracture: Vancouver Classification Types A, B1-B3, C.

⭐ Aseptic loosening is the most common cause for late revision of total hip arthroplasty.

High‑Yield Points - ⚡ Biggest Takeaways

  • Primary osteoarthritis is the most common indication for THA.
  • Posterior approach: most common, ↑ dislocation risk; Anterolateral: ↓ dislocation, potential abductor lurch.
  • Components: acetabular cup, femoral stem & head, liner. Polyethylene wear is a key long-term issue.
  • Cemented THA for older patients/poor bone stock; uncemented for younger/active individuals.
  • Complications: dislocation (early), infection, periprosthetic fracture, aseptic loosening (late).
  • Charnley: pioneer of low-friction arthroplasty (metal-on-polyethylene).
  • Metal-on-metal bearings: risk of pseudotumors and metallosis due to ion release.

Practice Questions: Total Hip Arthroplasty

Test your understanding with these related questions

Severe disability in primary osteoarthritis of hip is best managed by -

1 of 5

Flashcards: Total Hip Arthroplasty

1/6

Girdlestone arthroplasty preserves the hip joint _____.

TAP TO REVEAL ANSWER

Girdlestone arthroplasty preserves the hip joint _____.

mobility

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial