Carpal Tunnel Release (Cadaver)
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Carpal tunnel syndrome (CTS) is the most common peripheral compression neuropathy and results in symptoms of numbness and paraesthesia in the thumb, index finger, middle finger, and half of the ring finger. When CTS symptoms progress and can no longer be managed with nonoperative measures, carpal tunnel release (CTR) surgery is indicated. In this case, CTR surgery is performed on a cadaveric arm. The typical presentation of CTS is a pins and needles sensation in the hand that is most pronounced at night, affects sleep, and is not able to be controlled conservatively. The approach presented here is referred to as the “Mini-Open” CTR technique. A 2-cm longitudinal incision was placed directly over the carpal tunnel, the transverse carpal ligament was exposed and then released, and the wound was closed. Patients are typically sent home with instructions to use their hand immediately postoperatively, while avoiding strenuous use until the incision has healed. Splinting and therapy are not required postoperatively.
Carpal tunnel syndrome (CTS) is the most common peripheral compression neuropathy, affecting 5–7% of the population at large. CTS results in symptoms of numbness and paraesthesia in the thumb, index finger, middle finger, and half of the ring finger. Symptoms are typically the worst at nighttime or with prolonged use of the hand. Although many assume CTS is caused by repetitive use of the hand, in reality the etiology of CTS is multifactorial with causes including patients’ age, gender, weight, and comorbidities.1 Medical risk factors include diabetes, hypothyroidism, and any condition that increases fluid volumes in the body (e.g., pregnancy2). When CTS symptoms progress and can no longer be managed with nonoperative measures, carpal tunnel release surgery is indicated.
Carpal tunnel release (CTR) surgery is the most common surgery of the hand. It has evolved significantly over time, beginning with an extensile open release of the median nerve across the hand and distal forearm, to minimally invasive techniques including endoscopic and mini-open techniques. The technique being presented here is referred to as the “Mini-Open” CTR technique.
A 45-year-old female presents with many weeks of a pins and needles sensation in her right hand that is most pronounced at night, affecting her ability to sleep. She was given a wrist brace and treated conservatively with steroid injections with only temporary resolution of her symptoms. Physical examination of the hand identified baseline atrophy of the thenar muscles, paraesthesias in the median nerve distribution of the hand, and a positive response to provocative testing, including the Phalen’s test and Durkan’s compression test.
CTR surgery is indicated for patients who have persistent and/or advanced median nerve paraesthesias and thenar weakness. History and physical examination are typically sufficient to indicate a patient for surgery, but electrodiagnostic testing may also be of value to provide additional information about median nerve function.
The patient is positioned supine with the affected arm abducted across a hand table with the hand and forearm supinated palm up. The surgical site is infiltrated with 10–20 cc of a local anesthetic. The procedure can be performed with a local anesthetic alone but can be augmented with intravenous or regional anesthesia if so desired. Tourniquet hemostasis can also be applied if desired.
A 2-cm longitudinal incision is placed directly over the carpal tunnel. The exact position of the incision can be determined by placing the line in line with the third web space, or in line with the flexed ring finger, or in line with the palmaris longus tendon.
After completing the incision, the subcutaneous fat is retracted to reveal the superficial palmar fascia. This fascia is then sharply incised in line with the skin incision, revealing the transverse carpal ligament. There is often a muscle layer just deep to the fascia on top of the ligament, and this can be either cut through or elevated and swept aside to further expose the ligament.
Once the transverse carpal ligament is completely exposed, the ligament is sharply released longitudinally. The release is first performed distally. With the distal aspect exposed with retractors, the release is performed by gently pushing the scalpel blade into the ligament until it gives. This will immediately expose the median nerve itself and the flexor tendons of the hand. The distal release is confirmed once the ligament is no longer visible and the perivascular fat of the palmar arch is visible. For the proximal release, reposition the retractor to the proximal portion of the incision and expose the proximal part of the transverse carpal ligament. Often the proximal portion is tighter than the distal, and the release should extend across the crease of the wrist. The proximal release can be carefully performed with a scalpel, a fasciatome, or scissors. The median nerve should be visualized throughout the release to confirm it is both protected and released.
Once the nerve is released satisfactorily, the wound can be washed with normal saline, and closed with sutures, typically using about three interrupted stitches. The sutures will be removed in approximately ten days postoperatively. A soft dressing is applied.
Patients are allowed and encouraged to use their hand immediately postoperatively, while avoiding strenuous use until the incision has healed. Splinting is neither recommended nor required, but if the patient desires to utilize a splint, they may do so. Therapy is not required postoperatively.
Outcomes after CTR surgery are typically positive, with success rates hovering around 90%.3
Nothing to disclose.
Citations
- Lozano-Calderón S, Anthony S, Ring D. The quality and strength of evidence for etiology: example of carpal tunnel syndrome. J Hand Surg Am. 2008;33(4):525-538. doi:10.1016/j.jhsa.2008.01.004.
- Osterman M, Ilyas AM, Matzon JL. Carpal tunnel syndrome in pregnancy. Orthop Clin North Am. 2012;43(4):515-520. doi:10.1016/j.ocl.2012.07.020.
- Louie D, Earp B, Blazar P. Long-term outcomes of carpal tunnel release: a critical review of the literature. Hand (N Y). 2012;7(3):242-246. doi:10.1007/s11552-012-9429-x.
Cite this article
Acharya S, Ilyas AM. Carpal tunnel release (cadaver). J Med Insight. 2021;2021(206.1). doi:10.24296/jomi/206.1.
Procedure Outline
Table of Contents
Transcription
CHAPTER 1
My name is Asif Ilyas. I'm a Professor of Orthopedic Surgery and the Program Director of Hand Surgery at the Rothman Institute at Thomas Jefferson University in Philadelphia. We're going to be doing a carpal tunnel release procedure today. Carpal tunnel release is the most common hand surgery performed and amongst the most common orthopedic and plastic surgery performed. The indication for a carpal tunnel release is carpal tunnel syndrome, or a median nerve compression at the wrist where you develop paresthesias into the hand- very common phenomenon. And when it fails nonoperative treatment or it becomes recalcitrant to nonoperative treatment, and nonoperative treatment being splinting and injections primarily, and/or the disease is fairly advanced by exam or electrodiagnostic testing, then a carpal tunnel release surgery is indicated.
Now broadly speaking, a carpal tunnel release surgery can be performed in two ways: one in an open way, and one in an endoscopic way. Each of those general techniques have several subcategories as to how it can be performed. Today, we'll be performing it using an open technique - specifically, the mini-open technique, but as we go through the procedure, I'll show you some of the variations in terms of the approach, and techniques, and nuances. Also during the surgery, I'll show you some tips and perils and pitfalls in terms of how to manage carpal tunnel release intraoperatively.
CHAPTER 2
We are going to start with a carpal tunnel release. So a carpal tunnel release involves placing an incision directly over the - the carpal tunnel as well when you're doing an open technique. So, there's a couple ways to tell where to place the incision - you've got three broad ways you can tell. First is by placing the incision directly in line with the third web space, so the incision goes about like so. Another way is to use the ring finger and see if it lines up. Now I find this technique to be a little bit less sensitive because some people rotate a lot, but it's a common technique people say is to bring the ring finger down, and where it hits the palm is where the distal extent of the transverse carpal ligament is. I'm not so sure about that, but it's a - it's a common technique. Another is to use the palmaris longus if it's evident - in line with that. And the third thing is if they have a good inner thenar valley, you can use that. I think - I find the most reliable one is just using the third web space, like so, from about there to there.
So the mini-open technique is about a 1-in or 2-cm incision at the base of palm, like so. Now if you're doing an extensile release, your incision will go a little bit further proximal and distal, you'll go across the wrist crease, at an oblique angle, and go forward as well. But again, we're going to be doing what's called the mini-open technique. Now, if you're doing an endoscopic technique, there's typically an incision placed at the wrist crease, and, depending on your technique, a second one distal to the transverse carpal ligament, but again, we'll - proceed with the mini-open technique.
CHAPTER 3
So this is just a small incision, and we take this through the subcutaneous tissue. And the first layer you're going to come across is the trans - is the superficial palmar fascia.
CHAPTER 4
So I'm going to - I'll place the self-retainer here to show us some of that. So I'm still just going through the superficial tissue. Now you may have noticed, on this patient, that she's hollowed-out right here. That's called thenar atrophy. So that tells me right away that she has fairly advanced disease.
CHAPTER 5
All right, so, we're going to proceed, and the next layer we're going to find is the superficial palmar fascia. It's right below the fat. It's this softer layer, below. It's relatively wispy. A longitudinal cut through that layer will - will free that layer up quite readily. It has very little resistance to that, unlike the transverse carpal ligament that has a good amount of resistance to it. So I'm going to change this. I'm going to drop the self-retainer - a little bit deeper. I'll make sure we have adequate release of - the superficial layer. The better that's released, the more evident the ligament will be. So if we put in a retractor now, we'll have a direct view of the ligament right there.
All right, so once you get through the superficial palmar fascial layer, you'll come down to the transverse carpal ligament. Very often there's muscle over top of the ligament, covering it. You can buzz through it, or cut through it, or sweep it to the side. Here I'm going to do a - a sweep technique where I just sweep it to the side, and I will further expose - the ligament. So once you're - once you are exposed, it's just a release, again, release in line with the - with the third web space. And there's a couple ways to do the release. I like to just push through gently Until you get a give. And I'll show you in this in just a moment, and you'll see the tendons and/or the nerve itself - the flexgens or the - the median nerve itself, and you just go longitudinally.
CHAPTER 6
I'll pull back in a second so you can see a little better. It's a small field obviously. So I'm going to come in. The distal part has been released. And what you'll find is the median nerve and the flexor tendons - is that the carpal tunnel contains the median nerve most superficially, as well as the FPL, which is a flexor tendon to the thumb, the 4 FDS tendons, and the 4 FDP tendons. So this is the release of the distal aspect, and the question often comes up, how far distal to take the release, and the rule of thumb is you go to when the ligament loosens - the tautness of the ligament is gone. Or, until you see this yellowy fat distal to it. People will refer to it as the essential pad of fat, and what that represents is the perivascular fat of the arch - the vascular arch of the hand. Okay, so we're at that level now, but I find that it's quite evident when you're at the end of it. And moreover, most of the tension of the - of the carpal tunnel is really more proximal anyways. So I'm - I'm going to change this retractor, and I'm going to switch hands.
And now I'm going to actually do the proximal release. All right, so this is the proximal part right here. This is - I find this area to be quite tight, typically. And surprisingly thick. So now, we have a couple options. I'm going to retract here just so you can appreciate it a little bit better. At this level here - you want to do a release to about this level. So you can do that in 1 of 2 ways - you can do that with your knife the whole way, you can do it with the fasciatome, you can do it with the scissor - all those techniques are perfectly fine. The one thing I would tell you is just be a little bit careful with indiscriminate sliding of any sharp instruments proximally. I like to use a regular scissor, a Metz or a tenotomy, and I create a path first above and below the - ligaments.
I'm above right now, I have a nice path. And then I check below as well, make sure I have no resistance. And I'm hugging the tendon - I'm sorry, I'm hugging the ligament above, and the tendons are below me. Once I'm satisfied that I'm there, I'll do it in one motion. Like so. And if you have resistance - so that's one technique - and if you have resistance, you can also just go with your scissors as well. Again, I'm just showing you the different ways to do this. And release that as well. And I guess I'm going to have to cover you up for just 1 second, just so I can get in here for this part, and - it's hard to do without seeing it. And now it's released. And now if you look here, when I spread there, you'll see no resistance whatsoever, and you have a clear view of the contents of the carpal tunnel. And you'll see that the retracted leaflet of the transverse carpal ligament - the contents of the carpal tunnel - I can show you by moving the fingers, you'll see - the tendons move, as I move the fingers - back and forth like so. So, in terms of closure for this - it's a very routine closure.
CHAPTER 7
So, once you're satisfied with the release, you wash the wound. Then you close the incision. I use a simple nylon suture. I use interrupted mattresses - typically, 3 will do the trick. I typically will leave these sutures in for 10 days, plus or minus a couple days. The dressings - I place just a soft dressing on, no splints or anything. They're allowed to use your - their hands right away. I tell them writing, typing, eating, driving - all allowed and encouraged. And I ask them to leave my dressing on for 2 days, and after 2 days, they can take the dressing off. And then they can shower and wash normally. The way that I ask them to take care of the incision is, besides bathing normally, after 2 days, they clean the incision twice a day with some rubbing alcohol at least, and - and just apply either a soft dressing of their choice or a Band-Aid. Have them return to the office then in 10 days, approximately, to have the sutures removed. I do not typically recommend any formal physical therapy. Occasionally, if a patient feels very weak, or sore, or stiff, then therapy can be initiated. I also do not routinely recommend any kind of splinting afterwards, and they're welcome to if they would like, but not required.