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Cubital tunnel decompression- Revision with submuscular transposition and application of Axoguard

    Overview

    Learn the Cubital tunnel decompression: Revision with submuscular transposition and application of Axoguard surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Cubital tunnel decompression: Revision with submuscular transposition and application of Axoguard surgical procedure.
    Cubital tunnel syndrome is compression of the ulnar nerve around the elbow. Unlike carpal tunnel syndrome, the pathology in cubital tunnel syndrome can be variable. The common causes are due to extrinsic soft tissue constriction. Often due to a tight band called Osborne’s ligament (which extend between medial epicondyle and olecranon), tight medial upper arm fascia, a tight fascia over the Flexor carpi ulnaris (FCU) muscle or even a combination of these.
    A proportion of patients also have high tensile forces exerted across the nerve during elbow flexion, most pronounced in those with a cubitus valgus deformity.
    Patients with cubital tunnel syndrome are managed based on the severity of their symptoms. The commonly used grading system by McGowen is of use in evaluating the symptoms and is a validated grading system.
    Grade 1: Sensory symptoms
    Grade 2: Constant sensory symptoms with muscle weakness
    Grade 3: Muscle atrophy
    (McGowan AJ. The results of transposition of the ulnar nerve for traumatic ulnar neuritis. J Bone Joint Surg Br. Aug 1950;32-B(3):293-301).
    Those with intermittent symptoms can be managed with activity modification and nerve gliding exercises.
    If the symptoms are persistent, or if motor symptoms develop, surgery should be considered. Surgery is aimed at decompressing the nerve by releasing all restrictive structures. If the nerve appears to be subluxing over the medial epicondyle on elbow flexion or there appears to a significant tension on the nerve, then a transposition or medial epicondylectomy may be considered along with the decompression. Transposition can be carried out in the subcutaneous, submuscular or intramuscular planes. The choice of the procedure is often determined by the surgeons preference.
    If the symptoms do not resolve following a primary cubital decompression, revision surgery may be considered. Revision surgery is usually a neurolysis and either a transposition or a medial epicondylectomy.
    The case described here is of a patient who underwent a primary cubital tunnel release with temporary improvement in his symptoms. The procedure described is a revision cubital tunnel release with nerve wrapping using Axoguard(manufactured by Axogen)which is a neuroprotective membrane that reduces post operative adhesion formation, and a submuscular transposition.
    The AxoGuard nerve protector is made from layered porcine extracellular matrix and provides protection from scar formation and adherence to surrounding tissues. Rapid revascularisation allows soft tissue incorporation and restores nerve gliding.

    Readers will find the following OrthOracle surgical techniques also of interest:
    Cubital tunnel decompression: In-situ distal to proximal release of the ulnar nerve
    Cubital tunnel decompression with medial epicondylectomy
    Cubital tunnel decompression


    Indications

    INDICATIONS.
    The indications for performing a revision cubital tunnel release and submuscular transposition are recurrent symptoms or unresolved symptoms following a primary decompression.
    Submuscular transposition is done as a primary procedure when there is a subluxation of the nerve resulting following decompression or if it is felt that there is tension on the nerve during elbow flexion. Transposing the nerve anterior to the axis of elbow joint helps to relax it during elbow flexion.
    SYMPTOMS & EXAMINATION.
    Patients complain of pins and needles along the ulnar nerve distribution. The symptoms often come on during activities involving elbow flexion or while asleep. In more advanced cases patients may notice weakness of the hand and clawing of the ring and little fingers. The grip is weakened due to involvement of the intrinsic muscles and weakness of FDP to little finger.
    On examination there may be numbness along the ring and little fingers both on the palmar and dorsal aspects. Sensations may be tested in the clinic using a simple test called ‘Tens test’. The normal hand is scored as 10 out of 10 for sensation and compared to the effected side. The patient is asked to give a score for the sensations in the effected hand. Palmar and dorsal interossei are tested by asking the patient to abduct and adduct the fingers against resistance. There may be weakness of the interossei in advanced cubital tunnel syndrome. The adductor pollicis muscle is tested by asking the patient to hold a piece of paper or card between the thumb and index finger. If there is weakness of the adductor pollicis they instead tend to flex the thumb at interphalangeal joint, demonstrating what is known as ‘Froment’s sign’.
    If the patient is asked to keep the elbow flexed, they may start experiencing pins and needles along the ring and little fingers, which is a known as a positive provocative test. A positive ‘Tinel’s sign’ may be elicited by tapping along the course of the nerve above and below the elbow.
    IMAGING.
    Imaging is not indicated unless a pathology in the nerve is suspected, for example when the nerve is palpably swollen.
    An ultrasound scan is useful to assess the nerve in these cases.If there is ambiguity about the diagnosis of a cubital tunnel syndrome, ultrasound scan can be used as an adjunct to the diagnosis in which case perineural scarring or thickening of the nerve may be seen.
    Nerve conduction studies are helpful to confirm the diagnosis. However they are often negative even when there is established cubital tunnel syndrome.
    ALTERNATIVE OPERATIVE TREATMENT.
    The alternatives to submuscular transposition are subcutaneous transposition or medial epicondylectomy. There are proponents of each of these procedures.
    Subcutaneous transposition places the nerve in the subcutaneous plane anterior to the medial epicondyle. Proponents of this technique argue that it is a simple technique and places the nerve in a plane where there is no risk of compression. However subcutaneous transposition may create a kink in the nerve and may compromise the function of the nerve.
    Proponents of medial epicondylectomy believe that transposing the nerve can detach it from its blood supply and can compromise its function. They believe that a medial epicondylectomy can sufficiently de-tension the nerve. The downside of this procedure is the risk of causing iatrogenic injury to the medial collateral ligament of the elbow or the risk of elbow pain in the post-operative period.
    NON-OPERATIVE MANAGEMENT.
    If the symptoms can be managed with activity modifications, non-operative management can be tried.
    CONTRAINDICATIONS .
    There are no specific contraindications apart from a patient who is unfit due to anaesthetic contraindications.

    Setup

    The procedure may be performed under a Regional anaesthetic or General anaesthetic. Regional anaesthesia is usually a brachial plexus block. It is sometimes difficult to block the medial aspect of the upper arm with a brachial plexus block as it is supplied by the intercostobrachial nerve which is a branch of the second intercostal nerve with a contribution from the medial cutanous nerve of the arm. In that case a local anaesthetic infiltration in the upper arm will be required.
    In this case a Brachial plexus block has been used with an infiltration of 5mL of 0.5% Bupivacaine in the upper medial arm.
    An upper arm tourniquet is needed for the procedure. It is important to use a narrow tourniquet and to place it high in the arm to give enough space for the upper limit of the incision.
    The procedure is performed with the patient supine with the arm on the arm table.

    Operation – 1

    A 15cm skin incision is marked then incised mid-point between the medial epicondyle and the olecranon.
    The incision has been marked. As it can be seen it is a long incision unlike the one for a primary cubital tunnel release.
    The incision is marked distally towards the pisiform and proximally towards the upper arm.
    In this case there is a previous surgical scar which has been incorporated in the incision.

    The incision is made using a No.15 blade. As the incision is deepened, the cutaneous veins are seen and should be cauterised. The branches from the medial cutaneous nerve of the forearm should be identified and preserved. These branches have a variable course and may run oblique or sometimes transversely across the incision.

    In a revision case the initial dissection through the fat layer to identify the nerve needs to be very carefully done as the nerves position will be variable and obscured by scar tissue.A glimpse of the nerve can be seen in the distal end of the incision over the Flexor Carpi Ulnaris (FCU) muscle. As there is scar tissue around the nerve it is important to carefully dissect the tissue down to nerve. The course of ulnar nerve in the arm is behind the deep fascia between biceps and triceps muscles. As it travels down, it lies behind the medial epicondyle and travels into the forearm between the two heads of FCU muscle.

    A cutaneous nerve is identified in the scar tissue. This is a branch of the medial cutaneous nerve of the forearm. It is dissected free from the scar tissue and mobilised.
    A: Branch of medial cutaneous nerve of forearm

    The ulnar nerve is identified in the FCU muscle or in the medial aspect of the upper arm first.Trying to identify it in the groove behind the medial epicondyle is often hard. As this is a revision surgery there is scarring extending from the skin to the FCU fascia.
    The scar tissue is incised and the nerve is identified underneath the FCU fascia. If the scarring makes identification of the nerve difficult, the key is to extend the incision distally and identify the nerve in a normal plane and do a retrograde dissection.

    The nerve is dissected free from scar tissue. It is important to handle the nerve with care as traumatic dissection around the nerve can cause injury to the nerve.The adhesions around the nerve are carefully released using a tenotomy scissors or scalpel. When there are dense adhesions a sharp scalpel is a better dissecting tool than a scissors.

    The skin over the volar aspect of the forearm is raised exposing the flexor pronator muscles.This can be done using a No.15 scalpel. The dissection is in the plane between the superficial and deep fascia. Small perforators may be seen entering the skin and have to cauterised. Skin flap has to be raised up to the antecubital fossa.

    Dissection of the muscleThe exposed flexor pronator muscle mass can be seen with the ulnar nerve lying over the medial epicondyle.
    A: Flexor pronator muscles
    B: FCU muscle

    A “step-cut” incision is marked in the fascia between FCU and pronator teres.It is a step incision with FCU divided proximally and pronator flexor divided distally. The cleavage plane between the two muscle groups can be seen. This is where the vertical septum between these muscle groups lie.
    A: Flexor pronator muscles
    B: FCU muscle
    C: Medial epicondyle

    Following marking, incise the fascia in the middle between FCU and flexor pronator muscles.The fascia is then divided as shown over the flexor pronator muscle. The septum between FCU and flexor pronator muscle is identified.
    A: Surface marking of the septum

    The divided fascia over flexor pronator muscle exposes the underlying muscles.

    The muscle fibres of the flexor pronator muscles are divided using tenotomy scissors and reflected as a proximally based muscle flap.

    Fascia over FCU is incised exposing the muscle.

    FCU muscle is divided and raised as a flap and the vertical septum between the FCU and pronator is excised.The muscle is raised in a plane over the periosteum leaving a thin layer of muscle behind.
    The Ulnar nerve is retracted using a Ragnall retractor. Alternatively a vascular sloop can be used to retract the nerve.
    A: FCU muscle

    The two muscle flaps now raised and the bed for the nerve transposition is ready.Though it is termed a submuscular transposition, the plane created is an intramuscular one. As you can see the bed created is not directly over periosteum, there is a thin layer of muscle over the periosteum.
    There is a distally based FCU muscle flap and a proximally based flexor pronator muscle flap.
    A: Flexor pronator muscle flap
    B: FCU muscle flap

    The nerve is placed in between the muscle flaps and the position of the nerve is checked.
    The nerve should lie in line with the flexor muscles without kink or tension. This is checked by transposing the nerve.

    The position of the nerve after transposition can be seen here.

    Axoguard is prepared by soaking in salineAs it is a revision surgery consideration should be given to the perineural scarring which develops around the nerve. Therefore a decision to use a nerve wrap has been made. The wrap used here is Axoguard(Axogen corporation) which is a neuroprotective membrane taken from procine dermis. They come in various sizes and the one used here is 40mm x 10mm in size. Two of those are required in this case to wrap the nerve over 8cm in length. The sterile packet is opened and the membrane soaked in saline for 5 minutes to soften it.

    The membrane is taken out of the saline solution and wrapped around the nerve as shown. It is important that it is loose as there will be swelling of the nerve in the post-operative period.The memebrane should fully cover the circumference of the nerve and along the scarred segment.

    The membrane is sutured to itself to create a sleeve using 8-0 Ethilon.8-0 Ethilon sutures are placed between the edges of the membrane to create a sleeve. These are interrupted sutures and about four or five sutures should be enough. There is no need to suture the membrane to the epineurium of the nerve unless you feel that it is very loose and may slide off.

    Suturing of the membrane should be done with enough redundancy to allow for any swelling or bleeding around the nerve.

    The nerve with completed wrap can be seen here.

    The nerve is now transposed between the muscles.The new bed for the nerve between the muscles may form scar tissue.

    The two ends of the muscle flaps are sutured together using 4-0 PDS. A continuous suture is used through the full thickness of the muscle fibres.

    As the sutures are placed the muscle flaps come together placing the nerve in the submuscular pocket.
    A: Ulnar nerve with wrap in place

    Operation – 2

    The muscle repair is complete and the nerve can be seen lying anterior to the elbow joint, inside the muscles.
    A: Flexor pronator muscle
    B: FCU muscle

    Wound closureThe wound can now be closed in layers.

    Subcutaneous sutures are used to approximate the tissues. These are done using 3-0 Monocryl sutures.

    Skin approximation is done using continuous intradermal sutures with 3-0 Monocryl.

    Closed wound can be seen.

    Dressings are appliedThe wound is dressed with jelonet, gauze, velband and an above elbow POP backslab. It is important to immobilise the elbow as the muscle origins have been divided.

    Complete dressings and add backslabThe completed dressings and backslab.

    Post Operative

    Patient is discharged home the same day. The arm is to be kept elevated in a sling for 48 hours. Patient is advised to mobilise the fingers.
    Wound is checked in one week and an above elbow POP is applied for another 4 weeks.
    After 4 weeks the POP is removed.
    Physiotherapy is started to mobilise the elbow, wrist and fingers.
    Driving, domestic activities and light work can be started after 5 weeks from surgery.
    Strengthening exercises can be started after 6 weeks and in most cases patients can commence heavy work after 8 weeks.

    Recommended Reading

    Frantz LM, Adams JM, Granberry GS, Johnson SM, Hearon BF. J Shoulder Elbow Surg. 2019 Jun;28(6):1120-1129. Outcomes of ulnar nerve anterior transmuscular transposition and significance of ulnar nerve instability in cubital tunnel syndrome.
    The overall patient satisfaction rate was 92%, with statistically significant improvements in ulnar sensation and intrinsic strength at short- and long-term follow-up. Outcomes were better for lower McGowan grades than for higher grades and better in primary cases than in revision cases. Ulnar nerve instability was observed in 69 of 162 cases (43%) in this series. A major complication occurred in 7 cases (4.3%), but all were mitigated by contributory patient-related factors. Reoperation for recurrent ulnar paresthesia was required in 4 cases (2.5%). No operations or outcomes were compromised by the lateral decubitus position

    Wever N, de Ruiter GCW, Coert JH. Submuscular transposition with musculofascial lengthening for persistent or recurrent cubital tunnel syndrome in 34 patients. J Hand Surg Eur Vol. 2018 Mar.
    Of the 34 patients, 21 improved clinically after submuscular transposition with musculofascial lengthening, of which 16 were still satisfied at a mean follow-up of four years. In addition, all articles published between 1974 and January 2015 on subcutaneous and/or submuscular transposition of the ulnar nerve for recalcitrant cubital tunnel syndrome were reviewed. Previously published studies on this subject are too heterogeneous to compare. No recommendation can thus be made regarding the surgical technique for persistent or recurrent cubital tunnel syndrome. Our series shows that the musculofascial lengthening technique for submuscular transposition is a good option.

    Liu CH1, Wu SQ, Ke XB, Wang HL, Chen CX, Lai ZL, Zhuang ZY, Wu ZQ, Lin Q.Subcutaneous Versus Submuscular Anterior Transposition of the Ulnar Nerve for Cubital Tunnel Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials and Observational Studies. Medicine (Baltimore). 2015 Jul;94(29):e1207.
    PubMed, Cochrane Library, and EMBASE databases were searched for randomized and observational studies that compared subcutaneous transposition with submuscular transposition of ulnar nerve for cubital tunnel syndrome. The primary outcome was clinically relevant improvement in function compared to the baseline. Randomized and observational studies were separately analyzed with relative risks (RRs) and 95% confidence intervals. The available evidence is not adequately powered to identify the best anterior ulnar nerve transposition technique for cubital tunnel syndrome on the basis of clinical outcomes, that is, suggests that subcutaneous and submuscular anterior transposition might be equally effective in terms of postoperative clinical improvement. However, differences in clinical outcomes metrics should be noted, and these findings largely rely on the outcomes data from observational studies that are potentially subject to a high risk of selection bias. Therefore, more high-quality and adequately powered RCTs with standardized clinical outcomes metrics are necessary for proper comparison of these techniques.

    Reference

    • orthoracle.com

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