The Arthroscopic Subscapular Sling Procedure Results in Low Recurrent Anterior Shoulder Instability at 24 Months of Follow-Up.

PURPOSE: To analyze the results of the subscapular sling procedure developed for anterior shoulder instability in patients with less than 10% anterior glenoid bone loss. METHODS: Patients were treated surgically with the arthroscopic subscapular sling procedure. A semitendinosus graft was used to reconstruct the anterior labrum and to establish a sling suspension around the upper part of the subscapularis tendon. The patients were followed up with radiographs (at 12 and 24 months). Magnetic resonance imaging (MRI) of the shoulder region and clinical examinations were performed at 3, 12, and 24 months. Recurrent dislocation was the primary endpoint. The Western Ontario Shoulder Instability Index (WOSI) and MRI results were secondary outcome measures. An independent physiotherapist assessed residual instability and range of motion. RESULTS: Fifteen patients were included with a dislocation rate of 0% after 24 months follow-up. There was a significant clinical improvement of the WOSI score from 57% (904) at baseline to 88% (241) at 24 months (P < .001). The proportion of patients with an improvement in the WOSI Total score larger than the estimated minimal clinically important difference was 100% both at 12 and 24 months. MRI showed an intact sling in all patients. External rotation was not significantly reduced (52° at baseline vs 47° at 24 months, P = .211). Flexion and abduction were significantly improved from 152° to 174° (P = .001) and 141° to 170° (P < .001) after 24 months. The surgical procedures were completed without any intraoperative complications. CONCLUSIONS: The subscapular sling procedure resulted in low recurrent shoulder instability and improved patient-reported outcome measures at 24 months of follow-up. LEVEL OF EVIDENCE: Level IV, case series.

Region- and layer-specific investigations of the human menisci using SHG imaging and biaxial testing.

In this paper, we examine the region- and layer-specific collagen fiber morphology via second harmonic generation (SHG) in combination with planar biaxial tension testing to suggest a structure-based constitutive model for the human meniscal tissue. Five lateral and four medial menisci were utilized, with samples excised across the thickness from the anterior, mid-body, and posterior regions of each meniscus. An optical clearing protocol enhanced the scan depth. SHG imaging revealed that the top samples consisted of randomly oriented fibers with a mean fiber orientation of 43.3 o . The bottom samples were dominated by circumferentially organized fibers, with a mean orientation of 9.5 o . Biaxial testing revealed a clear anisotropic response, with the circumferential direction being stiffer than the radial direction. The bottom samples from the anterior region of the medial menisci exhibited higher circumferential elastic modulus with a mean value of 21 MPa. The data from the two testing protocols were combined to characterize the tissue with an anisotropic hyperelastic material model based on the generalized structure tensor approach. The model showed good agreement in representing the material anisotropy with a mean r 2 = 0.92.

Dynamic and Static Stabilization of Anterior Shoulder Instability With the Subscapular Sling Procedure.

There are numerous arthroscopic techniques available to address anterior shoulder instability. Complications are various, and in pursuit of new treatment options, an alternative arthroscopic technique with less potential for complications has been developed. The novel subscapular sling with a semitendinosus graft provides both dynamic and static stability. This procedure uses a semitendinosus graft as a sling around the upper two-thirds of the subscapular tendon, attached to the anterior glenoid rim. The sling phenomenon present in the Latarjet procedure was the basis of the development. The efficacy of the subscapular sling procedure has been verified in biomechanical studies and further investigated in a clinical pilot study. The procedure can be performed without altering the anatomy of nearby structures such as the coracoid process, the conjoined tendon, and the axillary and musculocutaneous nerves. The authors propose the arthroscopic subscapular sling procedure as an alternative to existing surgical treatment options for recurrent anterior shoulder instability.

The novel arthroscopic subscapular quadriceps tendon-bone sling procedure provides increased stability in shoulder cadavers with severe glenoid bone loss.

PURPOSE: Treatment of anterior glenoid bone loss in patients with recurrent anterior shoulder instability is a challenge. The subscapular sling method with quadriceps tendon bone (QTB) graft is a modification of the subscapular sling with a semitendinosus (ST) graft. The aim of the study was to test the biomechanical stability of the QTB sling procedure in human shoulder cadavers with severe anterior glenoid bone loss. METHODS: Fourteen cadaveric shoulders were tested with a force-moment-guided robot in three conditions: physiologically intact, anterior glenoid bone resection, and the subscapular sling procedure with a QTB graft. Joint stability was measured in anterior, anterior inferior and inferior directions in four glenohumeral joint positions: 0° and 60° of glenohumeral abduction, with each at 0° and 60° of external rotation. Maximum external rotation was measured at 0° and 60° glenohumeral abduction. Computer tomography scans were obtained preoperatively to plan the glenoid bone resection, as well as postoperatively to calculate the proportion of the glenoid bone actually resected. RESULTS: Significantly decreased translations were observed in the shoulders with the QTB sling compared to the intact joint and the glenoid bone loss model. No significant differences in maximum external rotation were observed between the three different conditions. CONCLUSION: This biomechanical study revealed a significant stabilizing effect of the arthroscopic subscapular QTB graft sling procedure in human shoulder cadavers without compromising external rotation. Clinical trials may reveal the usefulness of this experimental method.

The novel arthroscopic subscapular sling procedure grants better stability than an arthroscopic Bankart repair in a cadaveric study.

PURPOSE: This novel arthroscopic subscapular sling procedure stabilizes the shoulder using a semitendinosus graft to create a sling around the subscapular tendon, which provides both static and dynamic stability. The aim of the study was to evaluate the biomechanical stability of the subscapular sling procedure in human cadaveric shoulders. The hypothesis was that the sling offers an equal stabilizing effect and range of motion compared to an arthroscopic Bankart repair. METHODS: Sixteen shoulders were investigated using an industrial robot-based testing platform and four different conditions: the physiologically intact shoulder, after creating a Bankart lesion, after arthroscopic Bankart repair, and finally after applying the subscapular sling procedure using a semitendinosus tendon graft. Joint translation and external rotation were evaluated for each condition. RESULTS: The results show improved stability in the shoulders with the subscapular sling. The robot testing revealed a significant reduction in translation in anterior and anterior-inferior directions compared to the arthroscopic Bankart repair. None of the shoulders were dislocated by forced manual abduction and external rotation. No difficulties were encountered in performing the arthroscopic subscapular sling procedure. Thorough postoperative anatomical dissection showed no alterations to structures at risk. CONCLUSION: The biomechanical results show increased stability with the use of the subscapular sling method.