metal on metal hip replacements: the lessons learnt - clinical, surgical n personal!!!

Lessons learnt from MOM disaster

Dr Vaibhav BagariaMBBS, MS, FCPS

Joint Replacement Surgeon, CARE hospital & ORIGYN Clinic

Nagpur, INDIA

Lessons Learnt!

Technology

Metallurgy

Technique

Personal, Philosophical & other Funda’s

what did we learn?

Harmful effects of metal ions in body.

There are still unknown unknowns.

Tips tricks traps of revision arthroplasty

Gained experience on what to do when things go horribly wrong for surgeons.

remember this image!

what was MOM?First attempted in 1920’s, 30 designs so far, multiple failure.

Bearing surface always ignited interests because of less wear and hence increased longevity

Renewed interests with good results with BHR in 1990’s. Good biomechanics, bone preservation, hard bearing, marketed to young active population.

Most famous mom: AsR

• Depuy product

• First Released in 2003.

• Withdrawn from Australia in Dec 2009

• World-wide recall Aug 2010

Asr: good

• Bone Preserving.

• ?? Increased ROM

• Better Wear Characteristic in vitro.

• Good Instrumentation.

• Compatible/easily convertible to THR

what happened?

evaluation

History.

Examination

MRI

Blood Ion levels

Aspiration

Personal experience

• 10% catastrophic failure

• 10- 20 % Failing.

• 70% doing well.

Catastrophic failure

• Fracture

• Cup Migration/ Spin Out

• Infection

• Metal Ion related Inflammatory response: a.Osteolysis b. Solid or Cystic Pseudotumor c. Necrosis d. Muscle Disruption

preoperative planning

History: Function & Pain.

Examination: Trochanteric tenderness, ROM - irritability, Grating?clunking, Psoas & Abductor Power.

Make Sure it is not infected.

MRI: To know the abnormal tissue locations.

Preoperatve Asses

• Blood: CBC, LFT, ESR, CRP, Check Renal functions, Exclude Infections.

• Blood Cobalt & Chromium Levels: Controversial, Little Science - much opinion, Changing Goal Post.

Blood Metal levels

• Normal Levels: Agreement poor between labs. 2-7 vs 0-20nMol/L

• BOA/AOA statements: <40nMol/L OK; 3- 4x - cause of concern. toxicity >125nMol/L

Preoperative asses

• Xray: Positioning- Inclination Angle, Lucent Lines, Osteolysis, H.O

• MRI: Fluid Collection ( Joint Effusion, “bursal”, “Cystic Pseudotumor”, Synovial Thickening, Solid Pseudotumor ( FB Granuloma), Status Muscles/Tendons, Osteolysis)

intra-operative tech

Lots of unappreciated osteolysis - always have bone available.

Dislocation: downsizing bearing dia, pt used to hip that does not dislocate, deficient abductors.

Infection?: Masses of abnormal soft tissues, careful resection required.

Keep Constraints/ Explant available

Make Sure it is not Infected Infected

Resect all Abnormal Tissues

Cup Extraction

Use Explant

Have bone graft available

Use constraint if necessray

Implants usually Normal

Post operative

• Use drains as necessary.

• Hip Precautions: 3/12 to form pseudocapsule.

• Expect 90% reduction in Cobalt & Chrome levels in 3/12

Metal ions in body

Metal Hypersenstivity

Monk forced to sell ferrari

Text

One of My fellowship Trainers who had to leave his practice in Australia and take”sanyas””Every Tragedy has learning points - some deeply Personal.

Learn to Pick bad eggs

< -Be Wary of ‘miles ahead’ Technology and

Lawyers ->

New surgeons

Lessons Learnt!

• Be Careful!

Thank You!

Text

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