The Human Disharmony Loop: The Anatomic Source Behind Subacromial Impingement and Pain

Area of Science:

• Orthopedics
• Neurology
• Anatomy

Background:

• Subacromial impingement or pain syndrome (SAPS) is a leading cause of chronic shoulder pain.
• Existing surgical treatments for SAPS often fail to provide long-term pain relief, indicating a potential gap in understanding the underlying etiology.
• The Human Disharmony Loop (HDL) theory proposes that aberrant innervation of the pectoralis minor (PM) muscle leads to scapular dyskinesis and subacromial impingement.

Purpose of the Study:

• To investigate the efficacy of pectoralis minor tenotomy with infraclavicular brachial plexus neurolysis (PM + ICN) as a primary treatment for SAPS patients meeting HDL criteria.
• To determine if addressing the HDL can significantly alleviate pain and improve shoulder function in this patient population.

Main Methods:

• A cohort of 140 SAPS patients meeting HDL diagnostic criteria underwent PM + ICN surgery.
• Secondary distal neurolysis was performed if necessary.
• Outcomes, including pain levels and shoulder abduction range of motion (ROM), were assessed at a minimum six-month follow-up.

Main Results:

• Median pain scores decreased from 8 to 2, and median shoulder abduction ROM increased from 90 to 180 degrees (p < 0.01).
• Prevalence of positive impingement signs on examination dropped from 100% to 11%.
• A significant portion of patients had undergone prior shoulder or cervical spine surgeries without full resolution of symptoms.

Conclusions:

• Evaluation and treatment targeting the Human Disharmony Loop (HDL) demonstrated significant improvements in pain and motion for SAPS patients.
• These findings suggest that SAPS may represent a specific manifestation of the HDL, with the pectoralis minor muscle's role in scapular mechanics being a key anatomical basis.
• PM + ICN surgery presents a potentially effective surgical target for SAPS rooted in the HDL.