Broken Transverse Force Coupling as a Predictor of Poor Prognosis after Lower Trapezius Tendon Transfer

Area of Science:

• Orthopedic Surgery
• Sports Medicine
• Biomechanical Engineering

Background:

• Lower trapezius transfer (LTT) is a surgical option for irreparable posterosuperior massive rotator cuff tears (PSMRCTs).
• The transverse force couple is crucial for shoulder stability and function.
• Predictors of suboptimal recovery after LTT are not well understood.

Purpose of the Study:

• Evaluate clinical and radiologic outcomes of LTT for irreparable PSMRCTs.
• Identify prognostic factors for achieving clinically meaningful improvement after LTT.

Main Methods:

• Retrospective study of 44 patients undergoing LTT.
• Functional outcomes assessed at 12 months (VAS, ASES, SSV, UCLA, ROM).
• Postoperative MRI at 6 months to assess repair integrity; Patient Acceptable Symptom State (PASS) as primary outcome.

Main Results:

• 72.7% of patients achieved PASS.
• Graft tear (13.6%) and subscapularis retear (18.2%) were significantly associated with PASS failure.
• Independent risk factors for not achieving PASS included graft tear, subscapularis fatty infiltration, and smoking status.

Conclusions:

• Disruption of the transverse force couple (graft tear or subscapularis retear) negatively impacts LTT outcomes.
• Careful consideration is needed for patients at high risk of subscapularis retear.
• Optimizing transverse force couple integrity is key for successful LTT.