Appropriate hand, fingers, wrist, and forearm positioning is often required to facilitate proper exposure to the surgical site and anesthesia administration with easy accessibility to the intravenous (IV) site, and American Society of Anesthesiology (ASA) monitors for the anesthesiologist. The most common surgical positioning is supine, Trendelenburg, and lithotomy position. These positions often require arms in abduction less than 90-degree rested on the armrest or tugged in the neutral position. Whereas in the lateral position, the bottom limb is padded at bony prominence and placed in front of the patient, and the top limb is placed on top with padding in between the arms or flexed at shoulder and elbow. Prone position arms are abducted, but abduction should not exceed more than 90 degrees. An axillary roll is often utilized during prone positioning to prevent compression of the brachial plexus and axillary vascular structures.[1][2]

Even after new advances in medicine, perioperative peripheral nerve injuries continue to cause patient disability leading to multiple malpractice claims each year. According to the American Society of Anesthesiologist closed claim study, there were 11,000 claims between the years 2005 to 2014. Where 21% of all claims were related to nerve injury.[3][4] Ulnar neuropathy constituted one-third of the injuries, with the incidence of 0.2% to 0.5%. Brachial plexus nerve injury was reported as 23%, and radial nerve injury was infrequently encountered. Carpal tunnel syndrome from medial nerve injury was one the most common complaint in the disability claims, though median nerve injury reported incidence was only 0.1%.[3][5][6]

Ulnar nerve injury is one of the most common peripheral nerve injuries, likely due to the superficial nature of the nerve near medical condyle. Extreme elbow flexion in a prone position or direct nerve compression may be common modes of injury. Common complaints include numbness to the little finger and wrist. Claw hand deformity is also seen with ulnar nerve injury (flexion at the distal phalangeal and interphalangeal joints, and hyperextension at the metacarpophalangeal joints).[4] Brachial plexus injury is most commonly seen in lateral decubitus position with nerve getting compressed/tractioned near the humeral head.[7] Clinically, nerve injury can involve upper trunk C5-C6 causing Walter tip deformity (arm being medially rotated, adducted, and pronated). The involvement of lower trunk C8-T1 will result in claw hand deformity and numbness and weakness in the ulnar nerve distribution. Median nerve injury can result in carpal tunnel syndrome along with weakness/paresthesia around the wrist and radial three and a half fingers.[8] Radial nerve injury can result in numbness or wrist drop from improper positioning of the posterior part of the humerus.[8]

Proper communication between nursing staff, anesthesiologists, and surgeons is vital in the prevention of injury during hand positioning. Understanding the nature of the injury and constant surveillance of the patient can minimize the perioperative incidence of nerve injury. 

The ulnar nerve is commonly injured in prolonged surgery. Effort should be made to minimize the pressure on the ulnar nerve by tucking the patient's arms by side in a thumbs-up position. If abduction or flexion is needed, it should be less than 90 degrees. In laparoscopic surgeries where steep positioning is needed, patients on the bean bag with shoulder braces have shown significantly less displacement compared to the memory foam pad.[9][Level 2] Therefore, a bean bag and braces should be used in a Trendelenburg position to avoid cephalad shift and downward force on the shoulder. This can contribute to lowering the risk of injury to the upper brachial plexus.[2][1][3]

If the head rotation is required, such as in carotid endarterectomy, contralateral arm abduction should be avoided due to the risk of injury to the brachial plexus. Arms could be tucked at the side of the patient to avoid any excess traction. Overall, proper communication and frequent positioning checks could help reduce the incidence of injuries perioperatively.[6][10]