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Background: The split anconeus fascia transfer (SAFT) is an option for reconstruction of the lateral ulnar collateral ligament (LUCL) in chronic posterolateral rotatory instability (PLRI) of the elbow with potential advantages of using only local tissue within the surgical exposure and not requiring ulnar fixation. This study aimed to assess SAFT strength compared to a traditional free graft reconstruction in a PLRI biomechanical model., Methods: To measure biomechanical strength, eight cadaveric upper extremity pairs were utilized. Within each pair, one specimen was randomly assigned to LUCL reconstruction with autograft palmaris longus and the other to SAFT reconstruction. Torque load to failure was assessed on a load frame with the elbow in 30 degrees of flexion, 5 degrees of valgus, and 25 N axial load as the elbow was brought into external rotation. Torque load to failure was compared between the two reconstruction techniques., Results: No difference was found in the torque load to failure between SAFT specimens compared to palmaris longus autograft specimens (mean 14.6 ± 4.4 Nm vs. mean 11.3 ± 3.9 Nm; P  = .16)., Discussion: In this biomechanical study, the SAFT LUCL reconstruction provided torque load to failure similar to that of the traditional technique. These findings suggest that the SAFT technique warrants continued study as a biomechanically sound option for LUCL reconstruction in the setting of elbow PLRI., (© 2023 The Author(s).)

Background: Small changes in deltoid tension and moment arm due to glenosphere lateralization may be associated with an increase in acromion or scapular spine strain in reverse shoulder arthroplasty (RSA), which can lead to stress fracture. The coracoacromial ligament (CAL) may be protective and lower the strain seen on the acromion or scapular spine. This biomechanical study investigated the impact of glenosphere lateralization and CAL integrity on acromion and scapular spine strain after RSA., Methods: Ten cadaveric specimens were tested on a custom dynamic shoulder frame. Acromial and scapular spine strain were measured at 0°, 30°, and 60° of abduction using strain rosettes fixed to the acromion (Levy Type 2) and the scapular spine (Levy Type 3). Specimens were first tested with a standard commercially available RSA implant with zero lateralization and then subsequently with the +3 and +6 lateralizing glenospheres for that implant. The CAL was then cut in each specimen and testing was repeated with the 0, +3, and +6 glenospheres. Maximal strain was recorded at both the acromion and scapular spine and analysis of variance compared strain across various abduction angles and glenospheres with and without CAL transection., Results: In the intact CAL group, maximal strain decreased significantly at the acromion with abduction from 0° to 30° and 0° to 60°, however, at the scapular spine abduction did not significantly impact strain. Maximal strain decreased significantly with increasing abduction from 0 to 30 and 0 to 60 at both the acromion and scapular spine in the cut CAL group. Average strain at the acromion was significantly higher in the cut group (844.7 με) versus the intact group (580.3 με), a difference of 31.3% ( P  = .0493). Average strain at the scapular spine, did not differ in the cut group (725 με) compared with the intact group (787 με) ( P  = .3666). There were no statistically significant differences in acromial or scapular spine strain between various levels of glenosphere lateralization in either the cut or intact state., Conclusion: In this biomechanical study, arm abduction decreased acromial and scapular spine strain following RSA. Cutting the CAL significantly increased strain at the acromion, and did not significantly alter strain at the scapular spine for all angles of abduction, differing from prior literature. Glenosphere lateralization did not have a significant effect on strain at the levels studied regardless of CAL status. Continued study of the complexion relationship between surgical and implant factors on strain following RSA is needed., (© 2022 The Author(s).)