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Dual Mobility Liners: It Gives Stability and its Perfect for the - - PowerPoint PPT Presentation
Dual Mobility Liners: It Gives Stability and its Perfect for the - - PowerPoint PPT Presentation
Dual Mobility Liners: It Gives Stability and its Perfect for the Patient Douglas E Padgett, MD Chief, Adult Reconstruction and Joint Replacement Hospital For Special Surgery New York, NY Disclosures Consultant DJO Global PixarBio
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Fact: Dislocation after THR
Remains a problem for both surgeon and patient
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Fact: Instability after THR: Magnitude of the Problems
“Epidemiology of Revision THR”
– 22.5% of revision THR performed for instability
Bozic et al, J Bone Joint Surg, 2009
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Fact: Strategies to decrease Incidence of Instability
– Soft tissue repair – Improvement of Head-neck ratio – Larger head diameter
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Fact: Impact of Change: Reduction: down but not 0 !!
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Meanwhile, over in Europe: Use of Dual Mobility Sockets
Excellent track record in France
– Designers – Non-designers
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Confession: Personal Reluctance to Use
Concerns:
– Wear – Impingement – Modular version
Issues at the metal shell – liner interface
– 2 patients had MRI findings suspicious for ALTR J Arthroplasty 2016
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Improvement in Implant Delivery: The Safe Zone
“We seek the grail !”
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Two Problems with the “safe zone”
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Problem #1 with the safe zone: Can You Hit it ?
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MGH Data: 2000 THR’s 50% on target
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What About Enabling Technology ?
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Acetabular Cup Position: Lewinnek Zone Plot (n=119)
5 10 15 20 25 30 35 40 45 20 40 60 Cup Version (Degrees) Cup Inclination (Degrees)
* 10-30 version / 30-50 abduction
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Haptic THR: Initial Consectutive Experience
Used in selected patients with a tendency to use in
– dysplasia – Hypermobile – Prior spine surgery – Despite this, dislocation still occurs!
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Problem #2 Where is the safe zone ? (Is there really a safe zone ?)
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HSS Registry Data a tale of 7000 THR’s
2.1 % dislocation rate Dislocation rate the same in the “safe zone” and out of the “safe zone”
Esposito et al J Arthroplasty, Jan ‘15
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Why is this so ?
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Spino-pelvic Alignment (thanks to Larry Dorr, MD)
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So a 1-2% dislocation rate isn’t bad ! Why push it ?
A 1% risk of a complication is 100% if you’re the one with the problem ! Impact of bundled care !
– “You break it, you
- wn it!”
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Dual Mobility: Revisited
Stability
– Does it work ?
Wear
– Will it fail prematurely ?
Corrosion
– Interface
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Dual Mobility and ROM; Computational Analysis
Extremely favorable head-neck ratio Greatest benefit
- bserved in stablilty
was internal rotation at 90 of internal rotation
– (risk position for posterior dislocation)
Klingenstein et al JOA, 2013
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Dual Mobility Cup
Designers initial report 16 year followup:
– 437 hip – Non-selected (all comers) – 5 dislocations (1.1%) – No described lysis !
– Vielpeau et al International Ortho 2011
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Results of Dual Mobility Cups (high risk groups)
Caton et al:
– .9% dislocation rate at 10 yrs with Charnley
Benson et al:
– Used DMC for fx cohort: 2% dislocation
Epinette et al:
– Patients < 70 yrs – 0% dislocation at 4 yrs f/u
Increasing use in revision THR !
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2017 Otto Aufranc Award DM vs Large Diameter Heads
302 revision THRs
– 126 DM (47mm OD) – 176 40 mm head
Dislocation rates:
– DM 3% – LDH 10%
Re-revision / Reoper
– DM 1% 6% – LDH 6% 15%
Abdel et al, AAOS ‘17
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Wear in Dual Mobility
Simulator Clinical Studies
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Hip Simulator Impingement Setup
Impingement occurs at 50° Rotate cup additional 27° Interference of neck and chamfer from 0.02- 0.05 inches Despite impingement, minimal damage / wear reported
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DM Clinical Performance ex vivo
33 retrieved DM liners
– 29 ADM, 4 MDM – LOI mean 15 mos
Range 0-96 months
– Slight loss of machining marks outer bearing, more on inner – Deviation mapping:
Greater deviation inner than outer beargin
– Suggests most motion is at inner bearing D’Apuzzo et al, J Arthroplasty ‘16
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Corrosion at Modular DM Interface
Limited data Ion level in well functioning THR’s
– No difference btw
CoC, MoP, DM
HSS Retrieval lab:
– Light micro and selected SEM – No evidence of corrosion
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Conclusion: DM
Effective Low risk of wear Even the modular version:
– Safe !
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Summary
Etiology of instability remains enigmatic ! Despite the improvements in:
– Mechanics – Position – Delivery
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The Scariest Patient in America!
What do we do for this patient ?
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The Second Scariest Patient The 58 yo Hedge Fund Billionaire
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The Solution:
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