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

Abstract

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.