WHAT IS THE STABILIZING MECHANISM OF THE LATARJET PROCEDURE?
Authors: J Sperling; N Yamamoto; T Muraki; R Cofield; E Itoi; G Walch
References: Presented at SECEC 2009
The Latarjet procedure is one of the common procedures for treating patients with anterior shoulder instability. Recently, it has also been used as a bone-grafting procedure in patients with a large glenoid defect. " Sling effect " and " bone block effect " have been considered as the main stabilizing mechanisms. However, the precise stabilizing mechanism is still unknown. The purpose of this study is to determine the stabilizing mechanism of this procedure.
Material and Methods
Eight fresh-frozen cadaveric shoulders (mean age, 76 years) were investigated. A custom testing machine with a load-cell was utilized. With a 50-N axial force, the humeral head was translated in the anterior direction and the peak translational force was measured. At the end-range position: 1) with the capsule intact, 2) with a simulated Bankart lesion, 3) Latarjet procedure, 4) removing the conjoint tendon, and 5) removing the subscapularis tendon. The mid-range position was then examined. 6) With a 6-mm anterior glenoid defect, 7) Latarjet procedure with and without applied load to the subscapularis (10N, 20N, 30N) and conjoint tendons (2.5N, 7.5N, 12.5N), 8) removing the conjoint tendon, and 9) removing the subscapularis tendon.
At the end-range, the peak translational force significantly decreased after creating a Bankart lesion and significantly increased after the Latarjet procedure. After sectioning the conjoint and subscapularis tendons, it significantly decreased. At the mid-range, it significantly decreased after creating a glenoid defect. However, it significantly increased after the Latarjet procedure.
At the end-range, 75%-79% of the stability was contributed by the repair of the anterior capsular complex (capsular re-tensioning effect), and the contribution of the sling effect was 21%-25%. In the mid-range, 52%-70% of the stability was contributed by reconstruction of the glenoid concavity (glenoid plasty effect) and 30%-48% by the sling effect.