Summary

Superior Capsular Reconstruction and Lower Trapezius Tendon Transfer with Massive Rotator Cuff Tears improve function, with greatest improvements with combined SCR + LTT

Abstract

The treatment of irreparable massive rotator cuff tears (MRCTs) is a topic of debate, particularly for younger, active patients. When preserving the joint, procedures like superior capsular reconstruction (SCR) and lower trapezius tendon transfer (LTT) are the preferred options. This research utilizes a cadaveric model to compare the biomechanical efficacy of SCR and LTT with active control of the rotator cuff muscles.

Methods

Eight fresh-frozen human shoulder specimens from donors aged 55 to 75 were used. The cadaveric hemithorax was mounted on polycarbonate glass for biomechanical loading. A novel testing apparatus to allow for forces conformity to the shoulder joint motion and stability, allowing unrestricted humeral abduction from 0 to 90 degrees, preloading all rotator cuff muscles for smooth abduction. Data were collected across various experiment conditions.

Results

Transitioning from intact to MRCT reduced deltoid force by 28% (p = 0.023). LTT increased deltoid force by 27.25% (p = 0.166). Combining LTT with SCR increased deltoid force by 32.57% compared to SCR alone (p = 0.023) and decreased it by 13.6% compared to LTT alone (p = 0.017). Combined LTT and SCR reduced deltoid force by 20.9% from the intact condition (p = 0.001).
Significant differences in humeral head translation (HHT) were observed. HHT increased from 1.2 mm in the intact condition to 3.6 mm after MRCT (p < 0.001). LTT reduced HHT to 2.8 mm, SCR to 2.2 mm, and combining SCR and LTT further reduced HHT to 1.9 mm (p < 0.05).
Subacromial peak pressure increased from 2.1 MPa (intact) to 4.5 MPa (MRCT). LTT reduced peak pressure to 3.3 MPa, SCR to 2.7 MPa, and combining SCR and LTT brought it down to 2.4 MPa (p < 0.05).

Conclusions

Neither the SCR nor LTT biomechanical test fully replicated native shoulder kinematics, but their combination showed significant biomechanical advantages. Combining SCR and LTT optimally corrects humeral head translation and subacromial peak pressure. More to come on replicating and observing these results clinically.