Ulnar Nerve Transposition (Cadaver)

CHAPTER 1

My name is Asif Ilyas.I'm a professor of orthopedic surgeryand the program director of hand surgeryat the Rothman Institute in Philadelphiaat the Thomas Jefferson University.Today, we'll be talking about ulnar nerve transposition.Now ulnar nerve transposition is used to managesymptomatic cubital tunnel syndrome -also known as ulnar neuropathy of the elbow.That's when the ulnar nerve is under compressionas it traverses the cubital tunnelbehind the medial epicondyleat the level of the elbow.There's two broad ways to managecubital tunnel syndrome.One is with a cubi-an in situ cubital tunnel release,and the other iswith an ulnar nerve transposition.In this surgical video, we'll be looking atulnar nerve transposition.A transposition can be performed in a few ways,including subcutaneous, intramuscular, and submuscular.I'll be demonstrating both the subcutaneousas well as the submuscular technique.As we go through the procedure,I'll show you some tips and tricks andhazards to avoid. We'll also discusspostoperative management and rehab.

CHAPTER 2

Okay, so now we're going be addressingulnar neuropathy of the elbow,also known ascubital tunnel syndrome.You'll notice the armis flexed slightly,externally rotated.I'm looking at the posteromedial -posteromedial aspect of the elbow.The ulnar nerve is going to beright behind the medial epicondyle, and it is palpablein the specimen here.Now to manage, surgically, ulnar neuropathyof the elbow, you have two waysyou can approach this;you can do what is calledan in situ cubital tunnel releaseor an ulnar nerve transposition with neurolysis.Either way, the incision is placedin this aspect of the elbow,behind the medial epicondyle.So I'm going to mark outboth incisions to kind ofshare - to discuss how we go about this.So if you're doing anulnar nerve transposition,you bring the elbow straight.You'll feel the epicondyle here.The tendency is to bring the incisionanterior to the epicondyle,but recognize that you'll be awayfrom your - your nerve and alsoincrease the odds of injury inadvertentlyto the branches of the medial antebrachial cutaneous nerve.So with the elbow extended,I find it helpful to make arelatively straight incision.Behindthe elbow, which is the pathof the ulnar nerve.If I'm doing an ulnar transposition,centered on the medial epicondyle,my incision will go anywherefrom 6 to 8 cm distally -and similarly, about 6 to 10 cm, proximally.If I'm doing a cubital tunnel release,I can use the same incision.However, Ican also make a smaller incision -what I refer to as the mini open technique.And I'll use the same location on my incision,but I'll flex up the arma little bit moreto get a sense of where it is.And I place the incision directlybehind the medial epicondylelike so.If I'm taking the transposition,I'll go the full length.

CHAPTER 3

We do a long, longitudinal incision as marked out.Again, notice how the incision is fairly posterior,intentionally,to allow for easier exposure of the nerveas well asto decrease the odds ofinjuring or having to exposebranches of the medial antebrachial cutaneous nerve.

CHAPTER 4

And we'll start proximal.Tissue iseasier to manage and more viab- and,safer.Cauterize vessels as you go in.I do this procedure under - with the patient asleep -and with a sterile tourniquet.The nerve is readily foundproximal to the medial epicondyle, like so.

CHAPTER 5

It's mobilizedand released.What you're releasing is the arcadethat envelops it proximally.There's vessels that travel with the nerve,and you try to maintainas many of them as - as you can.I'm never grabbing the nerve;I just push the nerve.That's what I'm doing right now.Then I'll switch to usingeither a Penrose drain or an equivalent drainto help kind of control the nerve.So here's my nerve.I'm going to expose distally next.Okay, I'll try to use some retractors if possible.Let's see how they do.So much biggerexposurethan a cubital tunnel release.Again, this is a cadaver,so I'm cutting through some of these structures.But, you want to absolutely make surethey're not a nerve or a vessel.If they're a nerve,and you - you cut it by accident,you want to cauterize it, so as tonot cause any painful neuromas.And if it's a vessel,you similarly want to cauterize it.So the nerve is fairly wellmobilized, proximally.So I'm going to take that nerve release,distally, and you'll see it start to get tetheredwithin the medial epicondyle.We want to mobilize that.The first branch we'll come acrossis the articular branch to the joint.And that you can readily cauterize.And the first, most important branchyou'll get to are themotor branchesto FCU.So we're traversingthe cubital tunnel right here.There's adventitial tissue that holds it together.And here you'll seethe fasciabetween the two heads of FCU covering the nerve.So I will release that fasciain line with the nerve,like so.But I want you to appreciatethat there is also adeep investing fascia as wellthat can alsoput some compressionon the nerve,and you just spread through it.So,once mobilized,kind of gently pull away.As we do this,those first branches will become evident.Right here is probablythe first motor branchof FCU -right there.Now the question often comes up,what do you do with them?Well if you can maintain them, that's theoptimal thing to do. If you can't,then it's reasonable totake the first or second branch and cauterize it.The ulnar nerve innervates the FCUthe entire length of the arm,so if you take a branch or two,it will not result in any meaningful,denervation of the muscle -but avoid them if you can.Now you can see how loose the nerve isaltogether.

CHAPTER 6

So we want to transpose this anteriorly.So let's look at this now.So now that the nerve is released,we can transpose this in one of two ways;we can transpose thisin a subcutaneousor a submuscular fashion,and I will demonstrate both.

Either way,irrespective of which transposition you elect to do,the main structure you need to confirmis decompressed - or removed rather -is the intermuscular septum.The intermuscular septumis often considered a constricting elementto theulnar nerve,but frankly it's more of aconstricting structure to the ulnar nerve post-decompression.And I'll show you what I mean by that.So,here we go.So here is the intermuscular septum right here,and I'll expose it a little better for youso you can see it.It's this structure, right here,it comes off of the epicondyle,and it's quite palpable.And post-transposition, it can readilycause compression on the nerve, like so.So, it should be removed.So you can do this sharply,or you can do it with cautery.There are some bleeders back there,so cautery is a reasonable way todo this, but we'll use a knife here.You take it right off ofthe medial epicondyle.Again, there's a lot ofbleeding structures back here.So, I tend tocauterize very generouslyin this region.Again, with a cadaver limb,we don't have that senseof the bleeding that can occur.Once I'm exposed enough,I just excisea centimeter segmentofthat intermuscular septum.So now,what you'll notice,epicondyle's here,and there's a bare, supracondylar ridge,like so.So then when the nerveis transposed,it sits over that ridgewithout any kind of external structures bothering it.

So let's transpose this and see how it looks.So if we transpose this anteriorlyin a subcutaneous fashion,we see we're being tethered by this first branchof the ulnar nerve.So we have to make a decisionif we want to keep that or not.Like I mentioned, there are manybranches of theulnar nerve to the FCU.So I'll often cauterize that first base.So here I'll just cut it.I'll cauterize it,and that really helps to mobilizethis nerve even further.Once you transpose this anteriorly,the nerve's actually in moretensionand extension than in flexion,which is the opposite of normal.So you can see how it drapes over top.It can be under some tension.This patient's very thin,so you notice there'svery little tension on the nerve.But you'll also notice when I flexhow the nerve crimps upand has absolutely not tension on it.And most of usspend most of our timewith some amount of elbow flexion.So you'll notice how there's no tensionon the nerve once it's in this position.Now how do we stabilize this?Well there's a few waysto stabilize this nerve,and I'll show you thesubcutaneous technique first,and then the submuscular technique with a z-plasty.

CHAPTER 7

So when doing a subcutaneous transposition,the nerve moved anteriorly,the intermuscular septum taken down,I recommend two thingsto stabilize the nerve anteriorly.The first thing is to actuallyclose the cubital tunnelso that you prevent any inadvertentre-subluxation of the nerveback behind the epicondyle,because if it does, it will be trapped there.So what you do is you take your posterior tissues,mostly some triceps extension right here,and you just -you come acrossyour epicondyle,and you just close that interval.So typically, two sutures aremore than sufficient.I use two figure-of-eightsto close the interval down.And again, this is so that the nervedoes not inadvertently re-subluxinto the cubital tunnel.So that's the first thing.So once that's done,the second thing you want to doto stabilize the nerve,anteriorly, is you want to placesome kind of fascial slingto hold it in place.So once the cubital tunnelhas been closedwith some of the fascia of the triceps,you need a fascial sling to hold the nerveanteriorly.So I just take a little bitof the posterior aspect of the fasciaof FCUand come across like so.Leave it attachedto itsorigin on the epicondyleand then tease it back.And then this then is subsequently repaired.Repairedto here.Looking for a second pickup - here we go.So using a 2-0 Vicryl or equivalent,repair like so.And what that does with this repaired,it prevents the nerve fromtranslating posterior - it acts as a -a postor a bolster to prevent it from slipping back,as such.

CHAPTER 8

Alternatively,asubmuscular transposition can be done.And I will actually translate the nerveposteriorly, temporarily.And to do thiswith a z-plasty,the orientation you want to haveis basicallylike so.Okay?So we also already didsome of it,like so.And then we come across.It's a little short, but that's okay.And we come across like thisto complete the rest of it.Now how deep you take this is whatdefines whether this isan intramuscular or a submuscular.Obviously, this requires significantdissection and splitting of the FCU muscle belly.This is not my preferred wayto do transposition,but it is a very effective way to do it.And I'll use this technique in revision casesor cases where I need to bury the nerve a bit -maybe a complaint of neuritis orwhat have you, a thin patient -and that way it allows me tomake the nerve less palpable.And then these two ends -I'll show you the orientation again.They start like this,and then once we're done, it's like this.So let's move that nerve into this space here.Actually, I'm going to releasesome of this fascia here first.I have to stay close the epicondyleas the medial - median nerve is not far from here.So I don't want to wander too far away.I'm just staying on the supracondylar ridge.The nerve then just moves overto here,anteriorly.We have this branch here.This leaflet here and this leaflet hereis then repaired end-to-end, like so.One or twofigure-of-eight sutures will do the trick.You have to be mindful not to cause a newsite of constriction of the nerve.I'll just do onefor the sake of demonstration,but obviously, you can do moreas needed.Like so.Once done,you'll now have asubmuscular - or intramuscular - transpositionof the ulnar nerve.And let's take a look at that.So here's our bridge.It's been lengthened with a z-plasty.The nerve is below.You want to make sureyou absolutely haveplenty of room for the nerve.You want to checkyour nerve deep.Make sure it's satisfied and not tight.Here you'll find a little bit of residual tensionof that deep investing fascia that I had mentioned.I'll release that a little bit further.So here's that deep investing fascia.The nerve is deep to me.There's that fascial layer.I'll just release that a little bit further.Once released,you'll notice the nerve is very loose.I can easily pull itin either directionwith no tension on it.Like so.

CHAPTER 9

I then again take the nervethrough an active range of motionto confirm that there is no tension on it.Again, no tension.

CHAPTER 10

At this point, I typically drop the tourniquetas there's typicallyquite a lot of bleedingbecause of all of the cutting of theFCU - I'm sorry, the flexorpronator mass musculature.So I'll cauterize that until satisfied.I do no more additional deep closure.I just close the skin with 3-0 Vicryl or an equivalent,and a running 4-0 Monocryl,and then a glue for the skin,or a nylon for the skin.