Onlay versus Inlay Lower Trapezius Tendon transfer for posterosuperior functional irreparable rotator cuff tears: a 2-year clinical and imaging study.

BACKGROUND

This study compared the clinical and radiological outcomes of Onlay and Inlay Lower Trapezius Tendon (LTT) transfer techniques in managing posterosuperior Functional Irreparable Rotator Cuff Tears (FIRCTs).

METHODS

This retrospective comparative study included patients who underwent Onlay and Inlay LTT transfer. The inclusion criteria were FIRCTs defined by tendon retraction to the glenoid, fatty infiltration > 2 grade according to Goutallier, and with a positive External Rotation (ER) lag sign. Patients with irreparable subscapularis, dysfunctional deltoid, advanced glenohumeral osteoarthritis, cuff tear arthropathy, and revision surgeries were excluded. Outcomes measures included the active Range Of Motion (ROM), Acromiohumeral Distance (AHD), American Shoulder and Elbow Surgeons (ASES) score, Single Assessment Numeric Evaluation (SANE) score and Constant score.

RESULTS

The study included 39 patients (21 Onlay and 18 Inlay LTT) with at least 2-year follow-up. Both groups achieved significant improvement in active forward elevation from 118.6 ± 57.6° to 145.7 ± 18° in the Onlay group (p = 0.046) and 112.2 ± 49.2° to 140.6 ± 30.6° in the Inlay group (p = 0.046). The ER improved from 31 ± 21.2°to 44.3 ± 16° in the Onlay (p = 0.027) and 29.4 ± 27.1° to 45 ± 16.9° in the Inlay group (p = 0.046). The postoperative AHD was better in the Onlay group (7.3 ± 2.5 vs. 4.8 ± 3.2 mm, p = 0.001). The ASES, SANE, and Constant scores all improved significantly at final follow-up (all p < 0.001) in both groups and reached the Minimal Clinically Important Difference.

CONCLUSION

Both the onlay and Inlay techniques of LTT transfer effectively improved shoulder function in patients with irreparable posterosuperior rotator cuff tears. The Onlay technique resulted in better AHD at final follow-up.