How to perform a carpal tunnel release
Source
Surgeon:
Matti Mustaniemi (hand surgeon)
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Summary
Focus: Relief of median nerve compression by completely cutting the transverse carpal ligament.
Key elements: Incision landmark selection, direct visualization of the transverse carpal ligament, complete distal and proximal release, hemostasis, wound closure, and early postoperative mobilization.
Indications and Clinical Context
Step-by-Step Technique
Patient Positioning, Anesthesia, and Preparation
The patient is in supine position with the affected limb abducted laterally and the hand flat (in supination) on the operation table.
Local anesthesia: inject local anesthetic (i.e. lidocain) slowly with a 10 ml syringe, first at the carpal crease and then subcutaneously, along the operation area (5-10 ml required).
A tourniquet with a pressure setting of 100 mmHg over the last systolic reading can be used for hemorrhage control. Alternatively, use a local anesthetic supplemented with adrenaline.
Skin Incision
The proximal part of the transverse ligament attaches to the scaphoid tuberosity radially and the pisiform bone ulnarly, which can be palpated.
Inspect the landmarks:
distally Kaplan’s Cardinal Line
in the ulnar-radial direction thenar and hypothenar masses and/or the middle of the 4th finger flexion
proximally the wrist crease
Another commonly used way of defining the incision site is to draw the thenar crease and start the incision approximately 5 mm ulnar to that, ending on the level of the distal wrist crease.
Incising too radially may damage a palmar cutaneous branch of the median nerve or the flexor carpi radialis tendon sheath, while the ulnar neurovascular bundle could be damaged when operating too ulnarly. Be aware of these structures and make sure not to damage them. Too distal incision can lead to damage of the superficial palmar arch during the procedure.
Make a longitudinal skin incision parallel with the thenar crease approximately 2-4 cm in length according to your chosen landmarks.
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Piftalls and Complications
Pitfalls
Incorrect Site of Incision
The surrounding nerves, vessels, and tendons are in danger if the incision site is not chosen in an anatomically thoughtful way. Identifying key landmarks, such as the skin creases, will help you to prevent such damage.
Insufficient Knowledge of Anatomical Variations
The motor branch of the median nerve may display variations and, consequently, be prone to iatrogenic injury. In addition, the cutaneous branch of the ulnar nerve has a common variant that should be protected if faced while advancing through the subcutaneous fat. The surgeon should be aware of the potential variation of these nerves to reduce the risk of nerve damage. You can study the variations in the complications section.
Disorientation During Surgery
Insufficient recognition of critical tissues and layers, for example, misidentifying the palmar aponeurosis as the transverse carpal ligament, may lead to disorientation during the surgery.
Additionally, wrong positioning of patient/limb (hand pronation) can lead to a view that is too ulnar when performing the operation. Make sure that the hand stays correctly positioned while you operate.
Careless Tissue Handling
Excessive cutting through the distal part of the transverse ligament with scissors may damage the superficial palmar arch or digital nerves. The median nerve lies directly inferior to the transverse ligament and is in danger if the ligament is pierced carelessly.
When releasing the proximal part of the ligament keep in mind the cutaneous branch of the median nerve. If using curved scissors, hold them so the tips are facing ulnarly. Make sure to visualize the transverse ligament fully before cutting it.
Complications
Incompletely Cut Transverse Ligament
An incompletely cut ligament is the most common complication. Visualizing the edges of the ligament when cutting it, as well as verifying the accomplishment of goal afterwards, are crucial steps in avoiding this complication.
Tip: if necessary, extend the skin incision in order to visualize the edges of the ligament.
Median Nerve Palmar Cutaneous Branch Injury
Making the incision too radially elevates the risk of causing an injury to the palmar cutaneous branch of the median nerve.
Flexor Carpi Radialis Tendon Sheath Injury
Making the skin incision too radially elevates the risk of this injury.
Ulnar Nerve or Ulnar Artery Injury
Making the skin incision too ulnarly or not noticing pronation of the hand during the surgery may result in ending up in the Guyon canal and increase the risk of this injury at the pisiform level.
Motor Branch Injury
A too radial incision may result in damage to the motor branch of the median nerve. Also, careless operating through the subcutaneous fat tissue may result in damage to the motor branch if nerve variants are encountered.
Ulnar Nerve Cutaneous Branch Injury
Careless operation through the subcutaneous fat tissue may result in injury to a variant of the cutaneous branch of the ulnar nerve. A variant crossing the operating area at the distal third of the wound is found in about 20% of patients. When encountered this variant should be protected.
Median Nerve Injury
Piercing the transverse carpal ligament too deep or without sufficient visualization may result in damage to the main trunk of the median nerve running through the carpal tunnel.
Flexor Tendons Injury
Piercing the transverse carpal ligament too deep or without sufficient visualization may result in damage to the superficial flexor tendons running through the carpal tunnel.
Superficial Palmar Arch Injury
Visualizing the distal edge of the carpal ligament before cutting it and the appearance of fat tissue surrounding the superficial palmar arch from beneath the incised ligament should help in avoiding this complication.
Digital Nerve Injury
Careless tissue handling when cutting the distal part of the transverse ligament can lead to digital nerve injury. Visualizing the distal edge of the carpal ligament clearly before cutting and cutting it with care will prevent this rare injury.
Aftercare
General Guidelines
For most patients, early postoperative mobilization and return to daily activities are recommendable, while return to heavy manual labor may take up to several weeks.
FAQ
What is the goal of carpal tunnel release?
The goal is to relieve compression of the median nerve by cutting the transverse carpal ligament completely.
What diagnosis is associated with this procedure?
The diagnosis is carpal tunnel syndrome (ICD-10: G56.0).
What are the typical symptoms described in the source?
The typical symptoms are paresthesia of fingers I-III and the thenar area.
What is the most common complication?
An incompletely cut transverse ligament is the most common complication.
What structure is at risk if the incision is made too radially?
Making the incision too radially elevates the risk of injury to the palmar cutaneous branch of the median nerve and the flexor carpi radialis tendon sheath.
What aftercare is recommended for most patients?
For most patients, early postoperative mobilization and return to daily activities are recommendable, while return to heavy manual labor may take up to several weeks.
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