STUDY TO LOCALIZE ISOMETRIC POINTS OF ANTERIOR BAND OF INFERIOR GLENOHUMERAL LIGAMENT AND TO USE LONG HEAD OF BICEPS AS A GRAFT: A FINITE ELEMENT ANALYSIS AND ARTHROSCOPIC CADAVERIC DEMONSTRATION.

Abstract

Background: The inferior glenohumeral ligament (IGHL) comprising the anterior and posterior bands with interposing axillary pouch is an important static stabilizer of anterior translation and external rotation (ER) in the 90-degree abduction position. No literature is available to determine any ideal graft or isometric point for fixation of any graft to replace the functionality of IGHL such that the tensile stress acting on the graft is under the limits of the tensile properties of the graft used for reconstruction.

Methods: Using Finite element method analysis (FEM) of the long head of the Biceps tendon (LHBT) with Modelling and Simulation Process, the ultimate tensile strength of the LHBT at the different clock positions of the humeral head attachment and angular positions of the humerus were determined through a combination of Design of Experiments and Simulation using ANSYS (Analysis system) software.

Results: Through FEM simulations using the ANSYS software, it was concluded that the clock position of 7:30 would be appropriate to fix the biceps Tendon on the humerus. The tensile stress induced in the IGHL at 7:30 on the humerus, at 90° abduction with 90° rotation of the humerus, as well as at 120° abduction with 90° rotation of the humerus was evaluated and validated.

Conclusions: Reconstruction of anterior band of IGHL using LHBT in its isometric points found in this study can provide a solution to manage anterior instability anatomically rather than non-anatomical procedures like Dynamic anterior stabilisation. This will be an anatomical procedure which will bridge the gap between anatomical bankarts procedure and non-anatomical latarjet procedure. The LHBT can be suitable graft material for the anterior band of the IGHL reconstruction. Our study demonstrated that the most optimal fixation points for the graft, which resulted in the least tensile stress on the LHBT, were found to be at the 3 o'clock position on the glenoid and the 7:30 o'clock position on the humerus.

Level of evidence: LEVEL 5 - methodological verification and validation.