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

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.

Biomechanical comparison shows increased stability of an arthroscopic subscapular sling procedure compared to an open Latarjet reconstruction for anterior shoulder instability in specimens with major glenoid bone defect

Purpose

Recurrent anterior glenohumeral instability (RASI) is commonly treated with arthroscopic techniques, though their effectiveness in providing stability may diminish in cases of critical glenoid bone loss. This study aimed to compare the stability outcomes and range of motion (ROM) associated with an arthroscopic subscapular sling procedure (SSP), first introduced in 2015.

Methods

Sixteen fresh-frozen human cadaveric shoulder specimens were biomechanically evaluated in four conditions: native, injured, post-SSP and post-LP. Glenohumeral translations were measured under anterior, anteroinferior and inferior loading, while external rotation ROM was assessed in neutral and abducted positions. Testing was conducted using a robotic system for precise force and torque application. Specimens were prepared with a 20% glenoid bone defect and subjected to stability testing sequentially.

Results

The SSP significantly reduced glenohumeral translations compared to LP, particularly under anterior loading in neutral (p < 0.001), external rotation (p = 0.007) and abduction (p < 0.001) positions. Although the SSP demonstrated superior stability in these key positions, it did not consistently outperform the LP across all scenarios, as stability was similar between the two in the abducted and rotated position under anterior loading (p = 0.379). Under anteroinferior loading, the SSP showed comparatively better stability at neutral (p = 0.003) and abduction (p < 0.001), whereas the LP led to greater anteroinferior translations in these same positions (p = 0.002 and p = 0.014, respectively). The SSP outperformed the LP under inferior loading in neutral (p = 0.005) and abduction (p = 0.02) positions, though it did not fully restore stability to native shoulder levels. The SSP maintained ROM similar to native shoulders. LP allowed greater ROM, potentially compromising stability.

Conclusion

The SSP provided greater stability than the open Latarjet in most positions and did not limit ROM, suggesting it could be a viable, less invasive option for managing shoulder instability.

Level of Evidence

Not applicable.

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.