Question:
A patient, 3 hours post-forearm surgery, is unable to extend the fingers and wrist. What is the most likely cause?
A patient, 3 hours post-forearm surgery, is unable to extend the fingers and wrist. What is the most likely cause?
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Safe tourniquet time in the upper limb is generally limited to 90 to 120 minutes.
If surgery requires more time, the tourniquet must be deflated for 10-15 minutes (a "breather") to allow reperfusion and prevent ischemic nerve damage.
If surgery requires more time, the tourniquet must be deflated for 10-15 minutes (a "breather") to allow reperfusion and prevent ischemic nerve damage.
Updated On: Sep 3, 2026
- Radial nerve neuropraxia due to improper padding at the edge of the OT table
- Radial nerve neuropraxia due to prolonged tourniquet
- Median nerve injury due to excessive retraction
- Ulnar nerve injury due to positioning
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The Correct Option is B
Solution and Explanation
Concept:
The clinical scenario features a patient who develops an acute isolated motor deficit ("wrist drop") immediately following elective forearm surgery.
The clinician must identify the anatomical nerve responsible for this deficit and correlate it with the most common iatrogenic mechanism occurring during upper limb surgery.
Explanation:
• The inability to extend the wrist and fingers is the hallmark clinical presentation of a radial nerve motor palsy.
• The radial nerve innervates the entire extensor compartment of the forearm; thus, its injury directly causes "wrist drop."
• During most orthopedic or plastic forearm surgeries, a pneumatic tourniquet is routinely applied to the upper arm to provide a bloodless surgical field.
• The radial nerve lies directly against the periosteum of the humerus in the spiral groove, making it uniquely vulnerable to mechanical compression from an overlying inflated tourniquet.
• If the tourniquet is applied with excessive pressure or left inflated for a prolonged duration (usually $>1.5$ to 2 hours), it can cause significant mechanical deformation and focal ischemia to the nerve, a condition known as "tourniquet palsy."
• This typically results in a neuropraxia, a transient conduction block without axonal disruption, which usually recovers spontaneously over weeks to months.
• While improper table padding can cause nerve injuries, prolonged tourniquet use is the direct, most frequent, and classic cause of radial nerve neuropraxia in the context of ipsilateral forearm surgery.
• Median and ulnar nerve injuries would present with flexor deficits or intrinsic hand weakness, not an extensor deficit.
Final Answer:
Postoperative wrist drop after forearm surgery is most likely caused by radial nerve neuropraxia secondary to prolonged tourniquet compression.
The clinical scenario features a patient who develops an acute isolated motor deficit ("wrist drop") immediately following elective forearm surgery.
The clinician must identify the anatomical nerve responsible for this deficit and correlate it with the most common iatrogenic mechanism occurring during upper limb surgery.
Explanation:
• The inability to extend the wrist and fingers is the hallmark clinical presentation of a radial nerve motor palsy.
• The radial nerve innervates the entire extensor compartment of the forearm; thus, its injury directly causes "wrist drop."
• During most orthopedic or plastic forearm surgeries, a pneumatic tourniquet is routinely applied to the upper arm to provide a bloodless surgical field.
• The radial nerve lies directly against the periosteum of the humerus in the spiral groove, making it uniquely vulnerable to mechanical compression from an overlying inflated tourniquet.
• If the tourniquet is applied with excessive pressure or left inflated for a prolonged duration (usually $>1.5$ to 2 hours), it can cause significant mechanical deformation and focal ischemia to the nerve, a condition known as "tourniquet palsy."
• This typically results in a neuropraxia, a transient conduction block without axonal disruption, which usually recovers spontaneously over weeks to months.
• While improper table padding can cause nerve injuries, prolonged tourniquet use is the direct, most frequent, and classic cause of radial nerve neuropraxia in the context of ipsilateral forearm surgery.
• Median and ulnar nerve injuries would present with flexor deficits or intrinsic hand weakness, not an extensor deficit.
Final Answer:
Postoperative wrist drop after forearm surgery is most likely caused by radial nerve neuropraxia secondary to prolonged tourniquet compression.
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