The Addition of Remplissage to Free Bone Block Restores Translation and Stiffness Compared to Bone Block Alone or Latarjet in a Bipolar Bone Loss Model

Abstract

Purpose: The purpose of this study was to compare glenohumeral stability following a Latarjet, a free bone block (FBB), and a FBB with remplissage for bipolar bone loss.

Methods: Nine matched pairs of fresh frozen cadavers were tested in a custom biomechanical apparatus with rotation and progressive translational loading. The free bone block group consisted of a distal tibial allograft with an all-suture tape construct. The Latarjet group was performed with the native coracoid and two partially threaded cannulated screws. A bipolar bone loss model was created with 20% glenoid bone loss and an off-track Hill-Sachs lesion. Testing conditions included the 1) native state, 2) bipolar bone loss model, 3) Latarjet, 4) FBB with distal tibial allograft secured with cerclage sutures, and 5) FBB with remplissage. Each condition was tested for translation, humeral head apex shift, stiffness, and dislocation force.

Results: There were no differences in translation, stiffness, or dislocation forced between the FBB alone and Latarjet groups. The FBB with remplissage group demonstrated the lowest anterior-inferior translation at 90° of ER, which was statistically significant compared to Latarjet 20N (P = .013) and compared to the FBB alone at 40N (P = .024) and 50N (P = .011). The FBB with remplissage group was significantly stiffer compared to FBB alone at 90° ER with approximately 60% change in stiffness (P = .028). The force required to dislocate the humeral head after treatment was highest in the FBB with remplissage group, which was statistically significant compared to the FBB alone (P = .003) and Latarjet groups (P = .018).

Conclusion: The addition of remplissage to a FBB restores translation and stiffness closer to the intact state compared to a FBB alone or Latarjet in a bipolar bone loss model with an off-track Hill-Sachs lesion. In this model, dislocation force significantly increased with the addition of remplissage to the FBB.

Clinical relevance: This biomechanical study provides evidence that Latarjet and FBB are both acceptable forms of treatment for bipolar bone loss, but stability can be enhanced with the addition of remplissage following glenoid reconstruction.