Preventing brachial plexus injury during shoulder surgery: a real-time cadaveric study

Area of Science:

• Orthopedic Surgery
• Neuroscience
• Biomedical Engineering

Background:

• Brachial plexopathy is a known complication following shoulder surgery, often attributed to stretch neuropathy.
• The precise mechanisms and risk factors for developing brachial plexopathy during shoulder arthroplasty remain incompletely understood.
• This study investigated specific surgical conditions that may lead to brachial plexus injury during shoulder arthroplasty.

Purpose of the Study:

• To identify specific arm positions and surgical maneuvers that pose a risk for brachial plexopathy during shoulder arthroplasty.
• To quantify the tension on brachial plexus cords under various surgical conditions in a cadaveric model.

Main Methods:

• Tension measurements were taken from brachial plexus cords in six human cadaveric upper limbs using load cells.
• Limbs were positioned in various configurations simulating shoulder arthroplasty (hemiarthroplasty and revision reverse arthroplasty).
• Procedures were performed with unsupported arms and arms supported from under the elbow; biomechanical testing identified the 10% strain threshold for nerve injury.

Main Results:

• Tensions exceeding 15 N, 11 N, and 9 N on lateral, medial, and posterior cords, respectively, caused 10% strain.
• Shoulder abduction greater than 70° and combined external rotation (>60°) with extension (>50°) elevated medial cord tension beyond the 10% strain threshold.
• Unsupported arm positions during hemiarthroplasty and revision reverse arthroplasty significantly increased medial cord tensions compared to baseline and supported positions.

Conclusions:

• Arm positions involving significant shoulder abduction and external rotation with extension, along with downward forces on the humeral shaft, increase the risk of brachial plexopathy.
• Surgical steps such as retractor placement, sounder insertion, prosthesis impaction, and arthroplasty reduction contribute to elevated medial cord tension.
• Supporting the arm from under the elbow demonstrated a protective effect on the brachial plexus in this cadaveric study.