Summary

DAS combined with BR offered significant biomechanical improvements, substantial patient-reported outcome improvements, better forward elevation, high return-to-sport rates, and a low complication profile for ASI with subcritical GBL

Abstract

Introduction

Dynamic anterior shoulder stabilization (DAS) combined with Bankart repair (BR) has emerged as a promising technique for managing anterior shoulder instability (ASI) in cases of subcritical anterior glenoid bone loss (GBL). By transferring either the long head of the biceps tendon (LHBT) or the conjoint tendon (CJT) to the anterior glenoid, DAS potentially offers greater stability than isolated BR while avoiding the complications associated with coracoid transfer procedures. However, the evidence supporting DAS remains limited. This study aims to evaluate the biomechanical outcomes, clinical outcomes, and complication rates of DAS combined with BR for ASI.

Methods

PubMed, Embase, and Scopus were searched through August 2024 to identify biomechanical and clinical studies assessing DAS in ASI. Exclusion criteria included reviews, surgical techniques, case reports, and abstracts.
Biomechanical outcomes of interest included glenohumeral anterior translation, joint stability under various loading conditions, and load-to-dislocation. Clinical outcomes evaluated included patient-reported shoulder scores, range of motion (ROM), and complication rates. A meta-analysis was performed using a random-effects model, with using weighted mean differences (WMD) for continuous variables to compare pre-to-post treatment effects.

Results

Five biomechanical studies encompassing 60 cadaveric specimens were included with a GBL ranging between 10%-20%. DAS was performed by transferring the LHBT to the anterior glenoid only in four studies, while one study utilized either the LHBT or the CJT. Comparisons were various across studies, however tested treatments where isolated DAS, DAS + BR, isolated BR, remplissage, and the Latarjet procedure. DAS demonstrated significant improvements in anterior glenohumeral stability and load-to-dislocation compared to isolated BR, particularly in models with < 20% GBL and on-track Hill-Sachs lesion (HSL). In one study that compared two DAS techniques, LHBT transfer provided superior stability under higher loads compared to CJT. Despite these biomechanical advantages, DAS was less effective than the Latarjet and remplissage procedures in scenarios involving GBL of 20% or off-track HSL, respectively.

Three clinical studies involving 100 shoulders with a mean GBL ranging between 8.2% to 10.5% evaluated the outcomes of DAS. The mean age ranged from 23.4 years to 31.0 years. Two clinical studies employed DAS with LHBT, and one clinical study evaluated both DAS with a LHBT and CJT. Only one study reported HSL which was off-track. In term of clinical outcomes, a pre-to-post meta-analytic comparison was possible for the Rowe score, forward elevation ROM, external rotation ROM, and internal rotation ROM. At a mean follow-up ranging from 24 to 45.3 months, all studies reported significant pre-to-post intervention improvements in Rowe scores, with a mean difference of 58.7 points (WMD = 58.7; 95% CI, 50.3-67.2; p < 0.001) (Figure 1). Additionally, forward elevation significantly increased (WMD = 4.80; 95% CI, 0.8-8.8; p = 0.02) (Figure 2) without any statistically significant different in external or internal rotation. Return-to-sport rates were high, with a mean rate of 90% for return to sports at any level at two years, and a mean rate of 71% for returning at a similar level. Recurrent instability was reported in 8% (N=8 out 100) of patients in the form of postoperative apprehension in 3, subluxation in 1 and re-dislocation in 4, of which 3 were found to have an off-track HSL. Reoperations included revision to Latarjet in 2% (N=2) due to recurrent instability, and 1 capsular release due to post-operative stiffness. In terms of DAS technique, there was no statistically significant difference between DAS with LHBT or CJT.

Conclusion

Based on limited evidence from biomechanical studies and clinical studies, DAS combined with BR offered significant biomechanical improvements, substantial patient-reported outcome improvements, better forward elevation, high return-to-sport rates, and a low complication profile for ASI with subcritical GBL. However, caution is advised when considering DAS in cases with off-track HSL and GBL of approximately 20%, as it was found that DAS offers less stability biomechanically when compared to Remplissage and Latarjet and increased reoperations in such scenarios.