2021 ISAKOS Biennial Congress Paper
Superior Capsule Reconstruction Does Partially Restore Glenohumeral Stability In Massive Posterosuperior Rotator Cuff Deficiency - A Dynamic Robotic Shoulder Model
Lucca Lacheta, MD, München GERMANY
Alex Brady, MSc, Vail, CO UNITED STATES
Samuel I Rosenberg, MD, Chicago, Illinois UNITED STATES
Travis Dekker, MD, Niceville, Florida UNITED STATES
Ritesh Kashyap, MD, Vail UNITED STATES
Grant J Dornan, MS, Vail, CO UNITED STATES
Matthew T. Provencher, MD, Vail, CO UNITED STATES
Peter J. Millett, MD, MSc, Vail, CO UNITED STATES
Steadman Philippon Research Institute, Vail, Colorado, UNITED STATES
FDA Status Not Applicable
Summary
SCR for Posterosuperior Rotator Cuff Tears in a Robotic Shoulder Model
Abstract
Objective
To establish and report a dynamic robotic shoulder model, and assess the influence of rotator cuff tear patterns and SCR following a posterosuperior cuff tear on glenohumeral biomechanics. It was hypothesized that a posterosuperior rotator cuff tear would diminish glenohumeral stability when compared to the intact and supraspinatus tendon- deficient state, and that SCR would reverse this instability in the supra- and infraspinatus- deficient shoulder.
Methods
Twelve fresh-frozen cadaveric shoulders were tested using a 6-degrees-of-freedom robotic arm (KR 60-3; KUKA Robotics). Kinematic testing was performed in 4 conditions: (1) intact, (2) simulated irreparable supraspinatus tendon tear, (3) simulated irreparable supra- and infraspinatus tendon tear, and (4) SCR using a 3 mm thick dermal allograft (DA). Kinematic testing consisted of dynamic flexion and static 40-N superior force tests at neutral abduction, 30°, 60° and 90° of abduction. In each test, superior glenoid translation was measured, and for static testing, linear mixed-effects models were used to compare across repeated measures shoulder conditions at each abduction angle.
Results
In dynamic flexion testing, there was an average increase in superior translation of 2.1±1.7 mm for the supraspinatus cut state, 2.8±1.8 mm for the supra- and infraspinatus cut state, and 1.3±1.7 mm for SCR, when compared to the native state. In static testing, in all degrees of abduction the supraspinatus cut and the supra- and infraspinatus cut states showed a significant increase in superior translation compared to the native state (all p< 0.001). Supra- and infraspinatus cut increased superior translation significantly when compared to supraspinatus cut only in neutral and 60° of abduction (p=0.030 and p=0.022). SCR was able to significantly decrease superior translation in all degrees of abduction when compared to the supra- and infraspinatus cut (all p< 0.02), and in neutral position and 60° of abduction when compared to supraspinatus cut only (all p< 0.05). When compared to the native state, SCR was not able to restore superior stability with a significant increase of translation for neutral position, 30°, and 60° of abduction (p< 0.001).
Conclusion
Superior capsule reconstruction using a dermal allograft partially restored superior stability of the glenohumeral joint in the presence of a simulated massive posterosuperior rotator cuff tear in a dynamic and static robotic shoulder model.