Traditional versus congruent-arc Latarje anatomic and biomechanical perspective

The congruent-arc Latarjet (CAL) allows reconstruction of a greater percentage of glenoid bone deficit because the inferior surface of the coracoid is wider than the lateral edge of the coracoid used with the traditional Latarjet (TL). Biomechanical studies have shown higher initial fixation strength between the graft and the glenoid with the TL. In the TL, the undersurface of the coracoid, which is wider than the medial edge used with the CAL, remains in contact with the anterior edge of the glenoid, increasing the contact surface between both bones and thus facilitating bone consolidation. The shorter bone distance around the screw with the CAL is potentially less tolerant of screw-positioning error compared to the TL. Moreover, the wall of the screw tunnel is potentially more likely to fracture with the CAL due to the minimal space between the screw and the graft wall. CAL may be very difficult to perform in patients with very small coracoids such as small women or skeletally immature patients. Radius of curvature of the inferior face of the coracoid graft (used with the CAL) is similar to that of the native glenoid. This may potentially decrease contact pressure across the glenohumeral joint, avoiding degenerative changes in the long term.