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- RA - pan arthritis, Acetabular protrusion
- OA - mainly at weight bearing zone with osteopenia
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- This is a Complex primary
- Considerations are - medications, osteopenia, acetabular protrusio, higher risk of dislocation
- Pre Op
- Anaethesia review - Cervical instability, kiv “awake fibreoptic intubation“ kiv regional
- Medication titrations -
- Methotextrate - continue as no impact on wound healing
- Non biological DMARDSe.g. Azathioprine - continue
- Biologics e.g. TNF alpha inhibitor - stop 2-4 weeks before as they affect wound healing
- Steroids - may need stress dose
- Intraop for RA - osteopenia (intra op fractures) ➔ stand by contraint implants/ supplemental fixation, cemented implants
- Post op for RA - wound care paramount - higher risk of infection
- Stand by implants - cemented hybrid, consider dual mobility if there are also underlying neuromuscular disease
- Templating, LLD correction
- Intra Op
- Exposure - extensile, Psoas and glute max release, insitu neck cut
- Address protrusio
- Femur prep - gentle rasping
- Post op - standard post op
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- Determine by drawing the Kohler's line (ischioischial line)
- Defined by femoral head crossing or touching the ilioischial line.
- Medial wall > 3mm medial to ilioischial line in male or > 6mm in female
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- Coxa profunda is the floor going medial to the ilioischial line but NOT the femoral head
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- Idiopathic (aka Otto pelvis, Arthrokatadysis)
- Secondary -
- Infection - TB
- Inflammatory - RA, AS, Psoriatic Arthropathy
- Metabolic - Paget, OI, Osteomalacia, Renal osteodystrophy
- Connective tissue disorder - Sickle cell, Marfan, Ehler-Danlos
- Tumor
- Trauma - acetabular #
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- Hirst Classifx, JBJS 1987 Wrightington
- Grade 1 5-10mm
- Grade 2 10-15mm
- Grade 3 >15mm
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- Complex Primary, help of senior surgeon
- Goal - restore hip center (associated with early loosening if not achieved)
- Pre op
- Templating
- Stand by equipment -
- antiprotrusio cages [meant to be used without pelvic discontinuity]
- Triflange cages in the event of pelvic discontinuity
- Stand by allograft (in case autograft not enough)
- Intraop
- Approach - posterior KIV Extensile exposure (glute max/ psoas release)
- if for standard cup - May require adductor tenotomy, glute max release, may need insitu neck cut
- If for cage - May require trans-trochanteric approach to gain exposure to the ilium to insert the iliac flange
- Address protrusio defect by various means
- Standard hemispherical cup with bone grafting medially
- Augments
- Cage
- Plan for hybrid fixation - familiarity and good outcomes
- Post op
- Perhaps PWB for a while
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- Depends on the medial wall bone stock
- 1. Standard Hemispherical cup
- Use reamer to widen but not deepen the cup
- Insert morsellised graft (can be from femoral head) into prepared acetabulum, impact graft [impaction bone grafting]
- Insert cementless cup
- Can use revision hemispherical cup with multiple holes so to insert screws into ischium, pubic and ilium
- 2. Antiprotrusio cages
- Apply plate and fix with screws
- Cement liner into the cage
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- Restoration of hip center within 10mm of the anatomical center
- Bayley et al. Journal of Arthroplasty follow up of 93 THR found that
- 50% loosening is hip center not within 10mm of anatomical center.
- 8% loosening if hip center restored to within 10mm of anatomical center