What causes shoulder pain during foot surgery?

Shoulder Pain During Foot Surgery: Positioning-Related Brachial Plexus Injury

Shoulder pain during foot surgery is most commonly caused by positioning-related brachial plexus neuropathy from improper arm positioning, excessive arm abduction, or compression from shoulder braces used to prevent patient sliding during steep positioning.

Primary Mechanisms

The shoulder pain you're observing during foot surgery stems from perioperative peripheral nerve injury, specifically affecting the brachial plexus 1. This occurs through:

Direct Mechanical Compression

• Shoulder braces placed over the acromioclavicular joint to prevent cephalad sliding in steep Trendelenburg positioning directly compress the brachial plexus and increase neuropathy risk 1, 2
• Hard surface contact without adequate padding creates pressure points on neural structures
• Equipment (blood pressure cuffs, arm boards, retractors) can compress nerves when improperly positioned 2

Excessive Arm Abduction

• Arm abduction beyond 90 degrees in supine patients significantly increases brachial plexus stretch and injury risk 1
• This is particularly problematic during prolonged procedures where arms are positioned on arm boards

Inadequate Padding

• Unpadded or improperly padded arm boards fail to distribute pressure, concentrating force on vulnerable nerve pathways 1, 2
• Paradoxically, padding that is too tight can itself increase neuropathy risk 2

Prevention Algorithm

Immediate positioning checks during foot surgery:

1. Limit arm abduction to <90 degrees in supine patients 1
2. Avoid shoulder braces entirely when possible; if steep positioning is required, use alternative securing methods 1, 2
3. Use padded arm boards with appropriate thickness—not too tight, not too loose 1, 2
4. Periodically reassess upper extremity position during the procedure, even though the surgical site is the foot 1
5. Place chest rolls under the lateral thorax if lateral positioning is used 1, 2

Clinical Context

The ASA Practice Advisory emphasizes that positioning-related neuropathies can occur at sites distant from the surgical field 1. During foot surgery, anesthesia teams may focus exclusively on lower extremity positioning while neglecting upper extremity positioning, creating vulnerability for brachial plexus injury.

Common Pitfall

The most frequent error is using shoulder braces for patient stabilization during steep positioning—66% of both consultants and ASA members recognize this increases brachial plexus neuropathy risk 2. Eliminate shoulder braces from your positioning protocol.

Documentation Requirements

Document specific positioning actions on the anesthetic record, including arm position, padding type and placement, and absence of shoulder braces 1. This serves both quality improvement and medicolegal purposes.

Intraoperative Recognition

Examine upper extremity position every 30-60 minutes during prolonged foot procedures 1. Check for:

• Arm abduction angle (must be <90°)
• Padding integrity and placement
• Absence of visible compression from equipment
• Patient position stability without shoulder braces

The 2018 ASA guidelines represent the highest-quality evidence available, based on 114 acceptable studies and consensus from specialized task forces 1. While the evidence consists primarily of observational studies and case reports rather than randomized trials, the consistency across multiple sources and expert consensus provides strong guidance for clinical practice.