Assessing bone loss in instability lf 2016

Lennard Funk

Assessing Bone Loss in GHJ Instability

[email protected]

Is Bone Loss Important?

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1. Yes

2.No

www.wrightington.com

How much glenoid loss for Bony Reconstruction?

1. 5%

2. 10%

3. 20%

4. 25%


What is a significant Hill-Sachs Lesion?

1. 12.5% humeral head surface

2. 20% humeral head surface

3. 40% humeral head surface

4. Engaging at Arthroscopy


How do you assess Bone Loss?

1. X-Rays

2. MRI

3. CT

4. Arthroscopy

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Do you MEASURE the bone loss?

1. Yes

2.No

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“The extent to which beliefsare based on evidence is very much less than believers suppose”

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Bertrand Russell The Skeptical Essays, 1928


The problem with ‘Evidence’

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• 9 cadavers all soft tissues removed • Defects - 12.5%, 25%, 37.5%, 50% • Applied compressive + anterior load • Stability ratio = ant. load / compr. load

• All dislocated at 60deg. ER • 25% & 37.5% lower stability ratio



• 9 cadavers - skin & deltoid removed • Applied compressive + anterior load • Three positions: 0/0, 30/30, 60/60

• Translation, ant. capsule force, bony force • above 30/30 all sig. incr.



“The extent to which beliefsare based on evidence is very much less than believers suppose”

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Bertrand Russell The Skeptical Essays, 1928

GLENOID BONE LOSS

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How much?


Where does 20-25% come from?

Itoi Cadaveric Studies - JBJS, 2000: Stability of repaired cadaveric shoulders

With no glenoid removed With 21% anterior glenoid removed ER and ABER

Yamamoto & Itoi - AJSM, 2009 Stability ratio mechanical test 8 cadavers At 20% stability ratio greatly decreased

Yamamoto - JBJS, 2010 Same study (with 5 more shoulders)!!

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Pear

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Inverted Pear

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• Glenoid loss 20-30% • FU 34 months • 15% Recurrence rate

“requiring surgery”

• ‘Inverted Pear’ • FU 27 months • 67% Recurrence rate

(89% contact athletes)


Critical level of bone loss leading to increased recurrent instability and worse WOSI scores = 13.5%

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How much?


CT Scan reliable?Griffith Method: AJR 2008

‘En face’ CT compared to opp. normal glenoid in 218 anterior instability cases

High inter- and intra-observer reliability

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BUT: Only one study validating side-side reliability in Normals… 10 patients! Same authors and Journal: AJR, 2003


CT Scan reliable?Griffiths et al. 2007

CT vs. Arthroscopy (gold standard) Strong Correlation (r=0.79, 95%CI=0.659–0.877, p<0.0001)

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BUT: Measurements based on Bare Spot Not reliable marker

Miyatake 2014; Kralinger 2006; Sugaya 2014, Huysmans 2006


Huysmans, JSES 2006

Cadaveric study on 40 cadavers: Inferior glenoid is a circle Bare spot variable

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CT Reliable?‘Pico’ Method: Skeletal Radiol, 2009

40 shoulders compared opp. side ICC values 0.9-0.98

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BUT: Two observers, only one intra-observer Reformatting done prior to observers.


Problems with en-face methods

Glenoid face not flat Reformatting not standardised for axial reference image Don’t usually CT opposite shoulder

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What about MRI?MRI vs CT:

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Lee et al. 2013 vs. 2D CT r=0.83 YES

Moroder 2013 vs. 3D CT 35% sensitive

100% specific NO

Gyftopoulous 2012 vs. 2DCT & 3DCT

percent error :3DCT 2.17-3.5 %, 2DCT 2.22-17.1 %, MRI 2.06- 5.94 %

YES

All different methodology & statistical analysis


Glenoid Summary

No clear evidence on critical degree of bone loss

Discrepancy in outcomes

Arthroscopy not reliable gold standard

En-face measurements ? reproducible

If you do measure - ? need to CT opposite

‘normal’ side

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HUMERAL HEAD BONE LOSS

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What is a significant Hill-sachs lesion?

Bigliani & Flatow (1996) [quoted in Cetik (2007)]:

Mild - <20% Moderate - 20-45% Severe - >45%

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> 30% = Needs Treatment


Biomechanical Studies

5/8 radius in ABER; 7/8 radius neural ER (Kaar, 2010)

Defects as low as 12.5% dislocate in 60deg ER(Sekiya, 2009)

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Plain radiographs

Balg & Bouileau (2008) in ISIS: Visible on AP X-Ray in External Rotation

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Width(x) & depth(y) AP in 60deg. IR

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Plain radiographs: Hill-Sachs Quotient

Recurrence rate higher with a larger quotient (Grade I 23.3 %; grade II 16.2 %; grade III 66.7 %) Reliability and accuracy not been tested

Length(z) Bernageau view

HSQ = x.y.z

Grade: I <1.5cm2; II 1.5-2.5cm2; III > 2.5cm2

Kralinger, 2002


Plain radiographs: Radius Technique

Recurrence rate higher with a larger ratio (Sommaire):

d/R >20% = 40% recurrence d/R < 20% = 10% recurrence

Arth Stab failure rate (Hardy): d/R >15% = 60% failure d/R <15% = 15% failure

Hill-Sachs depth(d)/Humeral head radius(R)- AP in IR

Charrouset, 2010


CT

Hardy, 2012: Larger Width, depth & length = lower Duplay score, but not tested for reliability

Saito, 2009 & Cho, 2011: Good intra- & inter-reliability for depth & width on 2DCT

Kodali, 2011: Moderate reliability on 2DCT With percentage error of 13.6+/-8.4%

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MRI & Arthroscopy

No reliability studies for MRI!

Kirkley, 2003: MRI = Arthroscopy in detecting Hill-Sachs lesions (16 patients; no blinding)

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Funky Pizza Method

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‘Large’ Hill-Sachs LesionOne Pizza Slice = > 12.5% of the humeral head diameter Defects as low as 12.5% dislocate in 60deg ER(Sekiya, 2009)

Combined Glenoid + Humeral Head

Methods

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Balance Stability Angle - Matsen

Effective Glenoid Arc = the area of the glenoid’s articular surface available for humeral head compression Balance Stability Angle = the angle between the centre of the glenoid and the end of the effective glenoid arc in any direction (18 degrees anterior)

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‘Glenoid Track’ - Itoi & Yamamoto

Yamamoto - Cadaver

Metzger - MRI/MRA Omori - In-vivo

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Yamamoto N, Itoi E, Abe H, et al. JSES 2007 Metzger et al. AAOSM, 2010 Omori et al. AJSM. March 2014.

Defined as the contact area between the glenoid and the humeral head while keeping the arm in maximum external rotation, maximum horizontal extension, and 0° to 90° of abduction relative to the trunk.

If a Hill-Sachs lesion extends medially over the glenoid track, there is a risk of engagement.


Largest Track (contact) found in full ABER = 84% of glenoid width

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‘Glenoid Track’


‘Glenoid Track’

If the medial margin of a Hill-Sach’s lesion lies inside the glenoid track, this will cause an engaging Hill-Sach’s.

Bony defect of the glenoid will narrow the glenoid track


1. Measure the diameter (D) of the inferior glenoid, either by arthroscopy or from 3D CT scan.

2. Determine the width of the anterior glenoid bone loss (d). 3. Calculate the width of the glenoid track (GT) by the following

formula: GT=0.83D-d 4. Calculate the width of the HSI, which is the width of the Hill-

Sachs lesion (HS) plus the width of the bone bridge (BB) between the rotator cuff attachments and the lateral aspect of the Hill-Sachs lesion: HSI = HS + BB.

5. If HSI > GT, the HS is off track, or engaging. If HSI < GT, the HS is on track, or non-engaging.

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Normal Glenoid Track

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83%G


Anterior Glenoid Deficiency

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D

83%


The Formula:

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1. Measure the diameter (D) of the inferior glenoid, either by arthroscopy or from 3D CT scan (of Opposite shoulder).

2. Determine the width of the anterior glenoid bone loss (d).

3. Calculate the width of the glenoid track (GT) by the following formula: GT=0.83D-d

4. Calculate the width of the HSI, which is the width of the Hill-Sachs lesion (HS) plus the width of the bone bridge (BB) between the rotator cuff attachments and the lateral aspect of the Hill-Sachs lesion: HSI = HS + BB.

5. If HSI > GT, the HS is off track, or engaging. If HSI < GT, the HS is on track, or non-engaging.

D

83%


The Formula:

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1. Measure the diameter (D) of the inferior glenoid, either by arthroscopy or from 3D CT scan.

2. Determine the width of the anterior glenoid bone loss (d).

3. Calculate the width of the glenoid track (GT) by the following formula: GT=0.83D-d

4. Calculate the width of the HSI, which is the width of the Hill-Sachs lesion (HS) plus the width of the bone bridge (BB) between the rotator cuff attachments and the lateral aspect of the Hill-Sachs lesion: HSI = HS + BB.

1. If HSI > GT, the HS is ‘off track’, or engaging.

2.If HSI < GT, the HS is ‘on track’, or non-engaging.


Glenoid: Best fit circle (Huysmans)

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Humerus: Hill-Sachs on coronal

GT = 0.84xD-d HS

D

d

1.If HS > GT, the HS is ‘off track’, or engaging. 2.If HS < GT, the HS is ‘on track’, or non-engaging.

Simplified: Not validated


Two year period of 57 Bankart repairs On-track (49) - recurrence 4% Off-track (8) - recurrence 75%

PPV for Glenoid Track = 75% PPV for Glenoid loss >20% = 43%

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Summary:Radiography:

Insufficient accuracy Not sufficient for pre-op planning Useful for screening

CT: Most reliable, but need opposite shoulder Radiation exposure

MRI & Arthroscopy: No sufficient validation

ALSO: No consensus measuring technique No clarity on what a clinically significant lesion is!

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Thank You

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Assessing bone loss in instability lf 2016