Shoulder Dynamics Laboratory

Mechanobiology Lab | Tissue Mechanics Lab | Knee Kinematics & Robotics Lab | Computational Modeling


(From left to right) Jeff Murphy, John Jolly, Patrick McMahon, Carrie Voycheck, Richard Debski, Andrew Brown, Jon Sekiya, Nick Drury

• Richard E. Debski, PhD - Associate Director
• Patrick J. McMahon, MD
• Jon K. Sekiya, MD
• John Jolly, MS
• Carrie Voycheck
• Andrew Brown

1. Objective: Improve diagnostic exam for shoulder instability. A combined experimental and computational approach is utilized to develop subject-specific finite element models of the glenohumeral joint and examine effects of age/gender.
   
2. Grant: Funding Agency-National Institutes of Health (R01); Period of Support: April, 2004-March, 2008
   
3. Outcome: Optimize diagnostic tools and rehabilitation protocols

1. Objectives: Quantify contributions of muscles to stability or destabilizing forces and Identify characteristics of asymptomatic and symptomatic patients with rotator cuff tears
   
2. Grant: Student Grants and internal funding.
   
3. Outcomes: Predict which individuals most likely to cope with injury; Develop personalized treatment programs; and

1. Objective: Characterize the contributions of the osteoarticular surfaces to stability of the glenohumeral joint. Changes in joint stability will be determined in clinically relevant joint positions as lesions are created and then repaired.
2. Grant: Funding Agency-OREF-Research Grant; Period of Support: 7/1/07 - 6/31/09. Previous support from American Shoulder and Elbow Surgeons & Arthroscopy Association of North America
3. Outcome: Improved repair procedures for bony lesions.

1. Objective: Develop and validate a biomechanical model of the knee that can be used to determine the internal stresses in the knee from externally applied forces and moments similar to those found during the postures analyzed in kneeling and squatting work environments. This model will be developed through computer simulation and cadaver testing.
2. Grant: Funding Agency-National Institute of Occupational Safety and Health; Period of Support: 9/1/05-4/31/09
3. Outcome: Improve the health of miners’ knees.

• Debski RE, Moore SM, Mercer JL, Sacks MS, McMahon PJ: "The Collagen Fibers of the Anteroinferior Capsulolabrum Have Multi-axial Orientation to Resist Shoulder Dislocation”, Journal of Shoulder and Elbow Surgery, 12:247-252, 2003.
• Moore SM, McMahon PJ, Debski RE: "Bidirectional Mechanical Properties of the Axillary Pouch of the Glenohumeral Capsule: Implications for Modeling and Surgical Repair”, Journal of Biomechanical Engineering, 126:284-288, 2004.
• McMahon PJ, Burkart A, Musahl V, Debski RE: "Glenohumeral Translations are Increased After a Type II SLAP Lesion: A Cadaveric Study of Severity of Passive Stabilizer Injury”, Journal of Shoulder and Elbow Surgery, 13: 39-44, 2004.
• Jari R, Costic RC, Rodosky MW, Debski RE: "Biomechanical Evaluation of Three Common Reconstruction Procedures for Complete Dislocations of the Acromioclavicular Joint”, Arthroscopy, 20:237-245, 2004.
• Moore SM, Musahl V, McMahon PJ, Debski RE: "Multi-directional Kinematics of the Glenohumeral Joint during Simulated Simple Translation Tests: Impact on Clinical Diagnoses”, Journal of Orthopaedic Research, 22:889-894, 2004.
• Costic RS, Labriola JE, Rodosky MW, Debski RE: "Biomechanical Rationale for Development of Anatomic Reconstructions of Coracoclavicular Ligaments Following Complete Acromioclavicular Joint Dislocations”, American Journal of Sports Medicine, 32:1929-1936, 2004.
• Labriola JE, Jolly JT, McMahon PJ, Debski RE: "Active Stability of the Glenohumeral Joint Decreases in the Apprehension Position”, Clinical Biomechanics, 19:801-809, 2004.
• Debski RE, Weiss JA, Newman WJ, Moore SM, McMahon PJ: "Stress and Strain in the Anterior Band of the Inferior Glenohumeral Ligament during a Simulated Clinical Examination”, Journal of Shoulder and Elbow Surgery, 14S:24-31, 2005.
• Moore SM, McMahon PJ, Azemi E Debski RE: "Bidirectional Mechanical Properties of the Posterior Region of the Glenohumeral Capsule”, Journal of Biomechanics, 38:1365-1369, 2005.
• Konrad GG, Jolly JT, Labriola JE, McMahon PJ, Debski RE: "Thoracohumeral Muscle Activity Alters Glenohumeral Joint Biomechanics During Active Elevation”, Journal of Orthopaedic Research, 24:748-756, 2006.
• Moore SM, Stehle JH, Rainis EJ, McMahon PJ, Debski RE. The current anatomical description of the inferior glenohumeral ligament does not correlate with its functional role in positions of external rotation. J Orthop Res. 2008 Jun 3. [Epub ahead of print]
• Konrad GG, Sudkamp NP, Kruez PC, Jolly JT, McMahon PJ, Debski RE. Pectoralis major tendon transfers above or underneath the conjoint tendon in subscapularis-deficient shoulders. An in vitro biomechanical analysis. J Bone Joint Surg Am. 2007 Nov;89(11):2477-84
• Acromial morphology: effects of suboptimal radiographs. J Shoulder Elbow Surg. 2007 mar-Apr;16(2):135-42
• Kandemir U, Allaire RB, Jolly JT, Debski RE, McMahon PJ. The relationships between the orientation of the glenoid and tears of the rotator cuff. J Bone Joint Surg Br. 2006
• Musahl V, Moore SM, McMahon PJ, Debski RE: "Orientation Feedback during Simulated Simple Translation Tests has Little Clinical Significance on the Magnitude and Precision of Glenohumeral Joint Translations”, Knee Surgery, Sports Traumatology, Arthroscopy. 2006 Nov; 14(11):1194-9
• Konrad GG, Markmiller M, Jolly JT, Ruter AE, Sudkamp NP, McMahon PJ, Debski RE. Decresing glenoid inclination improves function in shoulders with simulated massive rotator cuff tears. Clin Biomech (Bristol, Avon) 2006 Nov;21(9):942-9.
• Ellis BJ, Debski RE, Moore SM, McMahon PJ, Weiss JA: "Methodology and Sensitivity Studies for Finite Element Modeling of the Inferior Glenohumeral Ligament Complex” Journal of Biomech. 2007;40(3):603-12.
• Konrad GG, Jolly JT, Labriola JE, McMahon PJ, Debski RE. Thoracohumeral muscle activity alters glenohumeral joint biomechanics during active abduction. J Orthop Res. 2006 Apr 24(4):748-56
• Moore SM, Thomas M, Woo SL, Gabriel MT, Kilger R, Debski RE. A novel methodology reproduce previously recorded six degrees of freedom kinematics on the same diarthrodial joint. J Biomech. 2006 39(10:1914-23

Figure 1. A) Robotic/UFS testing system and B) Shoulder Testing Apparatus Revison 4 (STAR4) to determine joint kinematics and in situ forces in ligaments.


Figure 2. A) Anterior view of a subject-specific finite element model of the glenohumeral capsule and B) Anterior view of a three-dimensional model of the shoulder muscles.


Figure 3. Superior view of inferior glenohumeral ligament.


Figure 4. A) Shear testing configuration and B) tensile testing configuration of the glenohumeral capsule.


Figure 5. Inferior view of glenohumeral joint showing strain markers used to experimentally determine strain distribution in capsule during various loading conditions.


Figure 6. Medial view of humeral head with A) lines indicating borders used for creation Hill-Sachs lesions that were 12.5%, 25%, and 37.5% of the humeral head diameter; B) humeral head with Hill-Sachs lesion comprising 37.5% of humeral head diameter.


Figure 7. Human knee within robotic/universal force-moment sensor testing system which is used to collect experimental inputs and validation for subject-specific finite element models.