Evolving Technique Update Cup positioning to avoid Metalosis Bone - - PowerPoint PPT Presentation

OS ET 2017 Bellagio Las Vegas

Evolving Technique Update Cup positioning to avoid Metalosis Bone preparation to avoid Failure of Ingrowth

Thomas Gross 8:52 AM 33

#1 Preventing Metalosis in Hip Resurfacing

using RAIL guidelines and NS IOR

Cause of Metalosis in HRA

 Poor cup posit ion

S teep inclination and excessive anteversion

 Poor implant design

DePuy AS R

 S

maller S izes women

 Edge loading, loss of fluid film

Relative Acetabular Inclination Limit

2013

 S

afe zone t o prevent met alosis

 S

maller bearing sizes need more horizont al posit ion

 Based on 777 cases wit h ions and st anding pelvis XR  99%

confidence “A Safe Zone for Acetabular Component Position in Metal-On- Metal Hip Resurfacing Arthroplasty”

Fei Liu PhD, Thomas P. Gross MD JOA 2013

RAIL chart for Biomet Magnum*

*also for Corin, BHR, ICON

Principle we have learned:

S hallower components must be placed more horizontal to avoid edge loading and AWF  S

hallow cup 40mm/ cup1540 Too vert ical

 Deep cup

60mm/ 1650

horizontal

Caveats:

RAIL is based on standing AIA

 MUS

T be measured on st anding pelvis XR

 Ant eversion must be set + 100 wrt TAL  IF TAL is not present , AV must be j udged qualit at ively on

NS IOR

Dynamic pelvic tilt (5-10% )

S upine

AIA =31

S tanding

AIA=40 More anteverted!

 Preoperat ive st anding pelvis XR  Digit al port able XR machine  Implant acet abular component  Use TAL as guide for AV  Est imat e AIA t o meet RAIL

How do you meet RAIL guidelines? NS IOR

S himadzu Ra Dt wireless digital

plate

Right hip rotated forward toward XR tube

 rotate OR table away from XR tube

Preop standing Initial intraop

Posterior tilt too low

tilt XR tube cephalad

preop 2nd intraop

Obturators match preop standing in width and height

achieved NS IOR measure “ standing” AIA

Preop standing Intraop “ standing”

Third intraop film

RAIL achieved

46 mm bearing < 400

Intraop “ standing” AIA= 33 Postop standing AIA= 33

Now Validation of RAIL in a separate patient series

0%

 1803 consecut ive cases 2010-2015  RAIL achieved in 100%

cases

 Ions opt imal in 98.8%

#2 Bone preparation to avoid

Failure of Ingrowth

The Wedge Fit Acetabular Technique

(developed in June 2012)

Failure of Ingrowth in HRA

 limited options for supplemental fixation  S

egmental defects solved with Trispike

 Others

0.7 % before 2 years Our hypothesis: Inadvertent apex contact

Magnum / recap Trispike

(available 2007)

Use with 30% wall deficiency

Cup fixation varies with standard preparation



Wedge Fit Apex “Loose” Apex Contact Edge “Loose”

Cup wobbles with weight bearing Cup seats in with weight bearing

Less contact pressure

Failure of Acetabular ingrowth

(without defect) DG 56 yo man nl bone initial postop XR

Failure of Acetabular ingrowth

(without defect) Fit military man running regularly. Presents with 2 months pain 22 months postop S udden worsening 2 months later

Question ?

If we could prepare the acetabulum so that every patient had a guarant eed wedge – fit, could we eliminate failure

• f ingrowth?

We would want to take into account bone density S egmental defects are already treated by trispike

Comparison of bone preparation

(only failures before 2 years are considered)

 Group I:

11/ 2004 through 5/ 2012

All Magnum cups

(n=2414)

All cases under reamed by 1 mm

 Group II: 6/ 2012 through 9/ 2015

All magnum cups

(n=868)

Wedge fit technique

Aft er init ial reaming, smaller reamer used at apex

Wedge fit Technique

Line to line ream in good bone (T score > -1.0) I mm under ream in poor bone (T score < -1.0) Ream 1-2mm apex bone with small reamer

Endpoints (before 2 years)

 Failure of ingrowt h  Init ial (asympt omat ic) cup shift s

(before 6 weeks)

 Unexplained pain  Excluded:

AWRF blood ions great er t han 10 ug/ L dysplasia before 2008

Results

Group I Group II p

n=2414 n=868 Failure of Ingrowth 0.7 % 0.02 Cup shift 0.7 % 0.1 % 0.04 Unexplained 3.8% 0.8% 0.004 pain

Interpretation

• 1. S

upplemental Fixation is required when there is a 30% segmental wall defect after preparation

Gaillard & Gross BMC 2016

no failure ingrowth in 242 dysplasia cases

Interpretation

• 2. Wedge Fit preparation eliminates the

remaining failures of bone ingrowth 100% reduction

(since 6/ 2012)

Component wedges in with weight bearing achieving a progressively tighter fit and loading the peripheral porous coating promoting bone ingrowth Inadvertent cases of primary apex contact and subsequent toggling micromotion are avoided

Interpretation

• 3. Early asymptomatic cup shifts are also

reduced by more secure initial wedge fit

0.8%  0.1% (90% reduction)

previously unrecognized phenomenon x-ray techniques not standardized subj ect of another publication

Interpretation

• 4. Reduction of unexplained pain (HHS

< 70)

3.8%

• ----- 0.8%

(80% reduction)

(NOT 20-30% as in THA and TKA)

suggests many cases of unexplained pain in HRA may be due to fibrous ingrowth caused by inadequate initial fixation

Other causes of unexplained pain

 LBP  Metalosis  Infection  Degenerative abductor tears  Psoas cup edge impingement  Nonspecific tendonitis  Neck on cup impingement  S

econdary gain (work comp, liability)

 Excessive patient expectations

(Minimal arthritis)

 Pain syndromes

(multiple allergies, high anxiety

• r depression score)

Wedge Fit Acetabular preparation

 Eliminat es revisions for ingrowt h failure

100%

 Reduces init ial asympt omat ic cup shift s

90%

 Reduces unexplained pain

80% all st at ist ically significant

Aft er init ial reaming, smaller reamer used at apex

Wedge Fit Technique

Line to line ream in good bone (T score > -1.0) I mm under ream in poor bone (T score < -1.0) Ream 1-2mm apex bone with small reamer