Comparison of Glenohumeral Contact Pressures and Contact Areas

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Comparison of Glenohumeral Contact Pressures and Contact Areas After Posterior Glenoid
Reconstruction With Iliac Crest or Distal Tibia Osteochondral Allograft
Rachel M. Frank, MD1, Jason J. Shin, MD2, Maristella F. Saccomanno3, Sanjeev Bhatia, MD4, Elizabeth Shewman, MS5,
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Vincent Wang, PhD , Brian J. Cole, MD, MBA , Matthew Provencher, MD , Nikhil N. Verma, MD , Anthony A. Romeo,
MD10
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Rush Univ, Chicago, IL, USA, 2Chicago, USA, 3Departments of Orthopedics, Catholic University, Rome, USA, 4Rush University
Department of Orthopaedics, Chicago, IL, USA, 5Rush Medical Center, Chicago, IL, USA, 6Rush University Medical Center,
Chicago, IL, USA, 7Midwest Orthopaedics at Rush, Chicago, IL, USA, 8Massachusetts General Hospital, Boston, MA, USA,
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Rush Presbyterian St. Luke's Medical Center, Chicago, IL, USA, 10Midwest Orthopaedics, Chicago, IL, USA.
Objectives: Posterior glenoid bone deficiency in the setting of posterior glenohumeral instability is typically
addressed with bone block augmentation with iliac crest bone graft (ICBG). While this technique aims at decreasing
posterior shoulder instability, the concern for the development of early, symptomatic, glenohumeral arthritis
remains. Reconstruction with distal tibia allograft (DTA) is an alternative option, with the theoretical advantages of
restoring the glenoid articular surface and improving joint congruity. The purpose of this study was to evaluate
glenohumeral contact areas, contact pressures, and peak forces in (1) the intact glenoid and after (2) 20% posterior
glenoid surface area defect from 6 o’clock to 10 o’clock (right shoulder), (3) 20% glenoid defect with flush posterior
bone block graft with ICBG; and (4) 20% glenoid defect with DTA. The hypothesis was that reconstruction with DTA
would more effectively restore normal glenoid contact pressures (CP), contact areas (CA), and peak forces (PF)
when compared to the deficient glenoid.
Methods: Eight fresh-frozen human cadaveric shoulders were randomly tested in four conditions as follows: (1)
intact glenoid, (2) 20% posterior-inferior glenoid surface area defect, (3) 20% defect reconstructed with flush ICBG;
and (4) 20% defect reconstructed with fresh DTA. For each condition, a 0.1mm-thick dynamic pressure-sensitive
pad (sensor model 5051, Tekscan, Boston, MA) was pre-calibrated and placed between the humerus and glenoid.
Each specimen was mounted onto a MTS testing machine (Insight 5, MTS systems, Eden Prairie, MN), which was
used to apply a compressive load of 440-N for each condition in the following clinically relevant arm positions: (1) 30
degrees humeral abduction, (2) 60 degrees humeral abduction, and (3) 30 degrees humeral abduction-90 degrees
flexion-45 degrees internal rotation (FIR). Glenohumeral CP (kg/cm2), CA (cm2), and joint PF (N) were recorded
(Figure 1). All data was analyzed with a repeated measures one-way analysis of variance (ANOVA) with Tukey’s
post- hoc test, when indicated.
Results: Glenoid reconstruction with DTA resulted in significantly higher CA compared to the 20% defect model at
60 degrees (P<0.01) and at FIR (P<0.01). The intact state exhibited significantly higher CA than the defect in all
positions (P<0.01), and significantly higher CA than ICBG at 60 degrees (P<0.05) and at FIR (P<0.05) (Table 1).
Reconstruction with DTA resulted in lower PF and higher CA compared to ICBG in all positions, however these
results were not statistically significant (P>0.05).
Conclusion: Reconstruction of posterior glenoid bone defects with DTA demonstrated at least equivalent
biomechanical properties compared to reconstruction with ICBG. Given the concern over the association of the
extra-articular, non-anatomic ICBG reconstruction technique with the development of early, symptomatic,
glenohumeral arthritis, this study suggests that posterior glenoid reconstruction with DTA is a viable alternative
solution, with the potential advantage of improving joint congruity via an anatomic reconstruction resulting in a
cartilaginous, congruent articulation with the humeral head. While these mechanical properties may translate into
clinical differences, further studies are needed to understand their effects over time.
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(http://creativecommons.org/licenses/by-nc-nd/3.0/), which permits the noncommercial use, distribution, and reproduction of the article in any medium, provided the
original author and source are credited. You may not alter, transform, or build upon this article without the permission of the Author(s). For reprints and permission
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The Orthopaedic Journal of Sports Medicine, 2(7)(suppl 2)
DOI: 10.1177/2325967114S00101
©The Author(s) 2014
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Table 1: Average Values of Glenohumeral Contact Area, Contact Pressure, and Peak Forces
Position
30
30
30
60
60
60
degrees degrees degrees degrees degrees degrees FIR
abduction abduction abduction abduction abduction abduction
FIR
FIR
Contact
Area
(cm2)
Contact
Contact
Peak
Pressure
Area
Force (N)
(kg/cm2)
(cm2)
Contact
Contact Contact Peak
Peak
Pressure
Area
Pressure Force
Force (N)
(kg/cm2)
(cm2) (kg/cm2) (N)
Intact
5.18
4.15
3.66
5.08
4.13
3.51
4.02
4.53
3.89
Defect
3.78
4.35
3.88
3.72
4.38
3.82
2.72
4.74
4.19
ICBG
4.31
4.19
3.79
4.44
4.29
3.97
3.35
4.46
3.90
DTA
4.33
4.22
3.75
4.67
4.14
3.62
3.65
4.58
3.83
Abbreviations: ICBG
(iliac crest bone graft);
DTA (distal tibia
allograft); FIR (flexion
internal rotation); N
(Newton); kg/cm2
(kilograms/centimeterssquared)
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