Suture anchor fixation strength in the Latarjet procedure: a biomechanical study in cadavers

Sutures, Screws, Buttons, and Anchors: A Review of Current Bone Graft Fixation Devices for Glenoid Bone Loss in the Unstable Shoulder

PURPOSE OF REVIEW

Anterior shoulder instability is associated with concomitant injury to several stabilizing structures of the shoulder, including glenoid bone loss. While instability is most common in young athletes and patients with predisposing conditions of hyperlaxity, recurrent shoulder instability can occur throughout various age ranges and may lead to longer term effects including pain and shoulder arthritis. Glenoid bone loss exceeding certain thresholds is generally treated by glenoid reconstruction via bone block augmentation to adequately stabilize the glenohumeral joint. These procedures increase the width of the articular surface on which the humeral head can translate before dislocation and, based on the procedure performed, provide a sling effect via the conjoined tendon, and increase tension to support the anterior capsule. The purpose of this review is to summarize the available literature regarding bone block fixation techniques.

RECENT DEVELOPMENTS

Various fixation techniques have been utilized to secure bone block transfers. Though screw fixation has traditionally been used for bone block fixation, suture buttons, suture anchors, and all-suture techniques have been utilized in attempts to avoid complications associated with the use of screws. Biomechanical studies report variable force-resistance, displacement, and mode of failure when comparing screw to suture button-based fixation of glenoid bone blocks. Clinical and radiographic studies have shown these novel suture-based techniques to be comparable, and in some cases advantageous, to traditional screw fixation techniques. While screw fixation has long been the standard of care in glenoid bone block procedures, it is associated with high complication rates, leading surgeons to endeavor toward new fixation techniques. In available biomechanical studies, screw fixation has consistently demonstrated high maximal load-to-failure and displacement with cyclic loading. Studies have reported similar clinical and radiographic outcomes in both screw and suture-based fixation methods, with evidence of reduced bone resorption with suture fixation. While suture button fixation is associated with a higher rate of recurrent instability, overall complication rates are low. Future research should address biomechanical shortcomings of suture-based fixation techniques and continue to assess long-term follow-up of patients treated with each fixation method.

Arthroscopic Technique for Distal Tibial Allograft Bone Augmentation With Suture Anchor Fixation for Anterior Shoulder Instability

Recurrent instability associated with glenoid bone loss is a commonly encountered problem after anterior shoulder dislocation. Surgical management with bony augmentation can be achieved with several allograft or autograft options. Fixation strategies also vary, including screw, suture button, or suture anchor fixation. Concerns exist regarding screw fixation because of the technical difficulty of a medial portal establishment, as well as the potential for graft osteolysis. Suture button fixation for osteochondral graft fixation has been previously described. However, no description of graft fixation using suture anchors exists. We describe an arthroscopic technique for glenoid augmentation using distal tibial allograft with suture anchor fixation.

Factors affecting biomechanical strength of Latarjet constructs: A systematic review and meta-regression

BACKGROUND

The Latarjet procedure reduces recurrent glenohumeral instability but has potential hardware and graft complications. The procedure has been modified to use various screw types as well as suture buttons. Biomechanical studies have evaluated the effect of these implants on construct strength. With varying results it is unclear whether there is an optimal implant to use.

METHODS

We conducted a systematic review of human cadaveric biomechanical studies evaluating Latarjet ultimate failure load. Two independent reviewers screened articles and included them after full text review. Additional factors including implants used, graft orientation, cortices engaged, drill diameter, and screw characteristics were recorded. Meta-regression was performed on the 145 specimens from eight studies that met inclusion criteria.

RESULTS

Screw fixation resulted in a 396.8 N (95% CI, 149.8-643.7) N higher ultimate failure load against shear stresses than suture buttons (p = 0.002). There were no differences between implants for ultimate failure load against tensile forces. Tensile strength was significantly affected by drill diameter with each millimeter of increase reducing the mean ultimate failure load by 127.4 N (95% CI, 41.2-213.6) N (p = 0.004).

CONCLUSIONS

These results suggest that using screw fixation and minimizing drill diameter can obtain the maximum ultimate failure load against both shear and tensile forces in a Latarjet construct.