Polypropylene mesh reinforcement does not improve acute biomechanical properties in superior capsular reconstruction: an ovine model study.

Abstract

<h4>Background</h4>Superior capsular reconstruction (SCR) is a treatment option for irreparable rotator cuff tears (IRCTs), yet graft failure remains a significant limitation. While fascia (FA) grafts are commonly used, postoperative outcomes can be suboptimal, potentially contributing to higher mechanical failure rates. Polypropylene mesh (PM) augmentation has shown promise in improving soft-tissue repair strength, but its acute biomechanical efficacy in SCR remains insufficiently investigated. This study aimed to evaluate whether PM augmentation enhances the biomechanical stability of FA grafts in SCR using an ovine model.<h4>Methods</h4>Ten fresh-frozen ovine cadaveric shoulders were used to model IRCT. Only one shoulder per animal was included to ensure specimen independence. Specimens were randomly assigned to two treatment groups: FA-only SCR (FA-SCR) and PM-reinforced FA-SCR (PMFA-SCR). In the PMFA-SCR group, the mesh was placed within the FA graft prior to folding and suturing. Grafts were fixed to the glenoid and humerus using suture anchors, with two anchors placed on the glenoid anterosuperior/posterosuperior and two on the humerus footprint anterior/posterior in all specimens. Biomechanical testing was conducted with a custom device, with specimens mounted at 30° abduction. Dynamic testing involved cyclic loading from 10 to 50 N at 1 Hz for 1000 cycles, with displacement and stiffness recorded. Immediately afterward, static load-to-failure testing was performed at a crosshead speed of 20 mm/min to determine the ultimate load, yield load, and failure mode. Data were analyzed using the Student's t-test.<h4>Results</h4>FA-SCR and PMFA-SCR demonstrated similar biomechanical performance, with comparable displacements both at the initial stage (p = 0.74) and after 1000 cycles (p = 0.83). No significant differences were observed in cumulative displacement (p = 0.63) or cyclic stiffness after the first or final cycle (p = 0.68 and p = 0.82). Static testing showed no significant differences in ultimate load-to-failure (p = 0.75), displacement (p = 0.57), yield load (p = 0.92), or final stiffness (p = 0.69).<h4>Conclusions</h4>In an acute ex vivo ovine model, PM augmentation did not improve the time-zero biomechanical performance of FA grafts in SCR, indicating that any potential benefit of mesh augmentation may be time-dependent and biologically mediated.<h4>Level of evidence</h4>V.