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Exploration of radial nerve and lateral cutaneous nerve of forearm and DCP implant removal

    Overview

    Learn the Exploration of radial nerve and lateral cutaneous nerve of forearm and DCP implant removal surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Exploration of radial nerve and lateral cutaneous nerve of forearm and DCP implant removal surgical procedure.
    Any surgical procedure puts peripheral nerves at risk of injury. This may occur during the surgical approach, or by retractors and other instrumentation used during the procedure. Nerves may become entrapped or tethered around implants or in the surgical scar.
    Patients typically present with signs and symptoms of nerve injury. Involvement of a sensory nerve, as in the following case, may be associated with pain, parasthaesia and reduced sensation. Left untreated, signs of chronicity may develop with central sensitisation and upregulation of pain pathways including psychological sequelae.
    Early diagnosis and appropriate intervention in these patients can be rewarding.
    The following technique describes my approach to the diagnosis and surgical management of a patient who was referred following injuries to the radial nerve and lateral cutaneous nerve of forearm during open reduction and internal fixation of the radius and ulna.
    The decision about whether to proceed to surgical exploration should be made by a surgeon with experience in treating peripheral nerve disorders. It is largely based upon the history and clinical findings but may be aided by neurophysiology, radiology and physiotherapy. The use of targeted peripheral nerve blocks can be invaluable.
    When exploring peripheral nerves in such a scenario, the peripheral nerve surgeon should be prepared for all eventualities, including the potential need to excise and graft a neuroma and in the use of adjuncts including nerve allograft and nerve wraps.
    Readers will also find of interest the following published techniques on OrthOracle, which explain some of the additional techniques referred to in this section.
    These include:
    1. The use of a nerve wrap
    2. The use of processed nerve allograft
    3. Reconstruction with autologous nerve graft

    Indications

    INDICATIONS
    The presence of parasthaesia and numbness within the distribution of a sensory nerve suggest injury to that nerve which may or may not recover spontaneously. The presence of a Tinels sign, neuropathic pain and autonomic disturbance are suggestive of axonal degeneration and may indicate rupture of the nerve.
    A static Tinels sign suggests neuroma in continuity or a frank rupture of the nerve but may also represent localised compression or tether in scar.
    A failure of progression to recovery within an expected timeframe, (often marked by an advancing Tinels sign) or deterioration under observation are indications to explore the nerve.
    Previous surgery to the area, as opposed to a closed injury, increases the suspicion of a sharp injury that may have divided the nerve.
    The presence of nerve tether pain (neurostenalgic pain) suggests adherence of the injured nerve to scar or implants and exploration and neurolysis can be rewarding.

    SYMPTOMS & EXAMINATION
    Sensation within the distribution of the injured nerves is carefully mapped out. A VAS scale can be used to quantify sensation. The quality of the sensation is important to note.
    The presence of a Tinels sign helps to locate the site of injury. A further strong Tinels sign distal to this suggests axonal regeneration and, depending upon timing of course, may herald some recovery.
    In this case the presence of severe exacerbation of nerve pain during wrist flexion and extension suggested nerve tether around the metal implants.
    The presence of allodynia in this case suggested some central sensitisation, but other features of this phenomenon were absent. Key features to look for include:
    Central sensitisation – an increased responsiveness of nociceptive neurons in the central nervous system to subthreshold stimuli.
    Allodynia – pain due to a stimulus that does not normally provoke pain.
    Hyperpathia – painful syndrome characterised by an abnormally painful reaction to a stimulus, often a repetitive stimulus.
    Hyperalgesia – an increased sensitivity to stimulation
    Dysasthaesia – an abnormal, unpleasant sensation which may be spontaneous or evoked.
    A validated pain questionnaire is useful baseline measure and can be referred to and repeated when assessing post operative recovery. We use our own modification of the McGill pain score. This allows the treating clinician to evaluate subtle changes in pain that may be difficult to detect. It also allows our research team to evaluate treatment efficacy.
    IMAGING
    Plain x-rays demonstrated the presence of a volar, LC-DCP plate in the distal radial shaft.
    The nerves were not imaged in this case as the decision to explore was made early. However an ultrasound scan can sometimes be useful to demonstrate continuity of nerve branches or to localise areas of nerve tether within scar or around implants.
    In a sensory nerve injury, neurophysiology can be invaluable in confirming injury to a specific nerve trunk and its location along the course of the nerve.
    ALTERNATIVE OPERATIVE TREATMENT
    Upon exploring the nerve a number of alternative surgical strategies exist. These depend upon the pre-operative clinical findings and the intra-operative picture.
    Following neurolysis the nerves may be wrapped in a nerve wrap such as the Axoguard porcine submucosal extracellular matrix wrap (described elsewhere on Orthoracle).
    A neuroma in continuity my require formal excision and autograft reconstruction. For short gaps in a sensory nerve an Axogen AVANCE, processed nerve allograft should be considered. In a patient with central sensitisation the use of autograft risks creating a second site of nerve pain and the AVANCE allograft may have a useful role in such patients.
    NON-OPERATIVE MANAGEMENT
    Hand therapy includes a number of desensitisation strategies for reducing neuropathic pain and improving nerve gliding through the scarred area. The use of pharmocological treatment of neuropathic pain and input from a pain specialist can be helpful.
    Repeating the examination at intervals is important as it will shed further light on any potential ongoing recovery that may be too slow to have been picked up by the patient.
    CONTRAINDICATIONS
    The presence of active infection is a contraindication to exploration.
    A fracture non-union under the plate may necessitate leaving the plate in situ, delaying the procedure until union (if feasible) or seeking an alternative means of stabilisation. This must be discussed with the referring orthopaedic surgeon beforehand.

    Setup

    The patient is positioned supine with the arm on an arm table.
    We perform this procedure under an regional anaesthetic technique using a brachial plexus block.
    A single dose of antibiotics is given.
    The WHO checklist is completed.
    An upper arm tourniquet is inflated.
    Bipolar and monopolar diathermy are made available.
    The tray should have a pair of Mixter forceps, nerve sloops, a pair of Debakeys forceps and a pair of Jamiesons scissors.
    We routinely use nerve stimulation if operating upon motor nerves but clearly this is not required for this particular case.
    A microscope and micro-instruments should be available if needed.
    Local thromboprophylaxis protocols are followed.

    Operation – 1

    The surgical incision is made along the radial and volar border of the forearm.
    In this case the previous surgical scar is used.
    It seems likely that a Henry’s approach was used by the previous surgeon.
    Both effected nerves are accessible via this approach and the Tinels points (marked with crosses) corresponding to the sites of injury or entrapment also lie within the approach.
    NB Henry’s approach utilises an internervous plane between muscles innervated by the the median and radial nerves.
    Proximally it utilises the interval between brachioradialis and pronator teres and distally between brachioradialis and flexor carpi radialis.

    The skin and superficial tissues are entered according to the Henry approachThe incision is made through the skin

    As the incision continues to the fascia, any traversing vessels are coagulated with bipolar diathermy.The lateral cutaneous nerve of the forearm will be lying over the fascia at this level and should be looked for. It may consist of more than one branch here. If one of these is found it can be traced proximally to locate the main nerve trunk.
    The superficial branch of the radial nerve will be deep to the brachioradialis muscle.

    The lateral cutaneous nerve of the forearm is looked for in the layer over the fascia and mobilised from the surrounding fibrous scar tissue.The nerve will likely be seen in the scar tissue over flexor carpi radialis.
    The scar is freed from the flexor carpi radialis with a blade where the nerve can be seen and protected.

    The lateral cutaneous nerve of the forearm is mobilised from the surrounding fibrous scar tissue.
    Its location here is right under one of the Tinels points marked on the skin.

    A sloop is placed around the lateral cutaneous nerve of forearm.The LCNF can now be handled atraumatically using the sloop.
    Gentle traction upon the nerve in each direction demonstrates points at which it is either thickened or tethered to areas of scar.
    Particular attention is focussed upon the areas of the nerve corresponding to the Tinels points marked on the skin.
    A – LCNF

    Neurolysis is performed, carefully freeing the nerve from the surrounding scar lying deep to itGentle traction upon the nerve demonstrates areas of scar tether (marked A). Where the course of the nerve is clearly visible, these may be be divided sharply with a blade.
    Often the nerve is encased in scar of a rather thicker nature. Dissecting out the nerve in such a scenario takes significantly longer.
    Techniques that are helpful include:
    1. Exposing the nerve both proximal and distal to the area of scarring, thereby confirming the exact course of the nerve and working into the difficult area from either.
    2. Using the sharp end of a 19G hypodermic needle to separate the poorly aligned scar fibres from the underlying epineurium.

    The terminal branch of the musculocutaneous nerve, passing behind the cephalic vein and piercing the deep fascia just lateral to the biceps tendon is neurolysed.
    This has divided at the elbow into volar and dorsal branches.
    Both branches run through this area of the distal forearm, this is likely to be the volar branch. Both branches communicate with the superficial radial nerve.
    Neurolysis is preferably performed in a proximal to distal direction to avoid entering the axilla of a nerve branch as it arises from the main nerve. This can result in avulsion of a nerve branch. It is less likely to occur in a proximal to distal direction.

    The brachioradialis is exposed in order to locate the superficial branch of the radial nerveThe LCNF is retracted medially to locate the superficial radial nerve.
    The first step is to find the brachioradialis which at this level lies along the radial border of the radius where it terminated as a broad insertion into the radial styloid.

    The cephalic vein overlies it here and is protected within the skin flap.

    The brachioradialis musculo-tendinous junction is seen here.
    The skin flap is elevated over it.
    Branches of the superficial radial nerve may come into view distally, emerging from the dorso-radial margin of the brachioradialis.
    It is important to be aware however, that in these cases the nerve may not be found as easily due to surrounding scar tissue or due to an altered course if tethered around the implants.

    The brachiradialis tendon is lifted away from the radial margin of the radius and the superficial branch of the radial nerve is looked for.This involves methodical dissection through the plane in which it usually lies.
    At this level I would expect it to be lying under brachioradialis.
    At a point 7-9cm proximal to the radiocarpal joint line the nerve leaves its submuscular location emerging along the dorsal margin of the brachioradialis tendon.

    The distal superficial radial nerve is exposed
    Distal to the plate the superficial radial nerve returns to its anatomical position under the brachioradialis tendon.
    Here there a gliding layer around the epineurium and no tether to surrounding scar. Exposing it here is a good strategy allowing the more tethered areas to be approached from both proximal and distal directions.

    Dissecting scissors are used to free the brachioradialis tendon along its dorsal margin.Ordinarily the nerve leaves its submuscular location emerging along the dorsal margin of the brachioradialis tendon at 7-9cm proximal to the wrist joint.

    In this slide a more distal nerve branch is encountered. This is part of the LCNF, which gives off a dorsal branch that overlies the brachioradialis tendon.
    This is mobilised and retracted to protect it.

    The superficial radial nerve is identified on the deep surface of the brachioradialis as this muscle is lifted away from the radius and is slooped and neurolysed.
    This nerve originates from the main radial nerve at the level of the radiocapitellar joint.It then runs distally under the cover of the brachioradialis muscle belly, lateral to the radial artery. It then pierces the deep fascia of the forearm approximately 7 cm proximal to the radiocarpal joint.
    It then crosses the anatomical snuffbox into the dorso-radial surface of hand dividing into a number of terminal branches, most commonly a lateral and a medial branch
    The abnormal course of the nerve is clear in this image. The nerve should at this level run under the brachioradialis tendon emerging from its dorso-lateral margin.
    Here the nerve situated rather more medially due to a tether point that is demonstrated in this image.

    Neurolysis continues proximal to distal along the length of the superficial radial nerveThe superficial radial nerve is neurolysed from proximal to distal.

    The most tethered area of the superficial radial nerve is closely adherent to the radial plate.
    The plate is just palpable and is located at point A.
    Before attempting to free the nerve in this difficult area, an attempt is made to expose the more distal aspect of the nerve where the anatomy is more easily delineated.

    Sharp dissection is feasible where the position of the superficial radial nerve is clear.
    The more superficial branches of the LCNF are protected.

    The portion of the superficial branch of the radial nerve just distal to the most dense area of scarring next to the plate is now visible at point A.

    The distal part of the nerve is slooped
    The red sloop is around the superficial radial nerve.

    This image demonstrates the freed proximal and distal ends of the superficial radial nerve as well as the densely adherent portion in between.
    A Proximal superficial radial nerve
    B Tethered portion of superficial radial nerve
    C Distal superficial radial nerve
    D LCNF

    The most tethered part can be freed from scar working from either end with sharp and blunt dissection
    The densely scarred and tethered area of the superficial radial nerve is now carefully freed from the scar tissue between nerve and plate.

    A 360 degree neurolysis of the superficial radial nerve is performed. Here the entire length of the superficial radial nerve has been freed.

    With the nerve free the plate is exposed within the same segment of scar tissue
    The plate is exposed by sharp dissection.

    Operation – 2

    With the nerve free the plate is exposed within the same segment of scar tissue
    The plate is exposed by sharp dissection.

    The pronator teres tendon lies over the plate.
    Its fibres are carefully dissected free.

    The superficial radial nerve, once fully exposed, is inspected for signs of injuryThe entire length of the superficial radial nerve is now free.
    It is inspected for signs of injury. A neuroma in continuity may be seen at the Tinels points marked out on the skin.
    There is epineurial thickening corresponding to the area of scar tether but no obvious neuroma.
    For there to be positive Tinels sign there must be a degree of axonal degeneration. With the nerve neurolysed here, and the tether point resolved, one can expect some further regeneration to occur. This ought to result in improved sensation over time. Results are difficult to predict however.
    The presence of a neuroma with some intact sensation presents a difficult dilemma. A number of options are available in such a situation:
    1. Excise and graft the neuroma in the hope of improving sensation and reducing neuropathic pain over time.
    2. Perform a neurectomy, leaving the sensory territory of the nerve devoid of sensation with the aim of reducing pain. Adjuncts such as burial of the stump or the use of nerve caps are described elsewhere.
    3. Treat the neuromatous part of the nerve with excision and grafting whilst preserving intact fascicles. In my experience it is rare that the microanatomy is seldom delinieated clearly enough to reliably attempt this technique .

    The plate is completely exposed in preparation for removalThe plate can now be removed after exposure with a periosteal elevator.

    Sharp dissection is performed around the screw headsIt is important to expose the screw heads completely to correctly seat the screwdriver.

    The screws are removed

    The plate is grasped with Kochers forceps.
    It proves difficult to lift away from the bone at the first attempt .
    There is a possibility of some remaining screws and this a further check is made before mobilising the plate further.

    The plate is teased away from the radius with an elevatorA periosteal elevator helps lift the plate away from the bone.
    Often some bone ingrowth from the drill holes exists and can be freed up using the elevator.
    The nerves are both protected at this stage but care is taken to avoid applying sudden force to the plate which can injure the exposed nerves lying over it.

    The plate now lifts off easily.

    The plate leaves a raw area of bone to which further nerve tether can occur.
    Furthermore the screw holes often leave sharp edges that can cause nerve or tendon injury.

    Sharp bone spikes around the screw holes are removed to leave a smooth surfaceUsing my finger, I am able to feel any sharp spikes of bone that put nerves and tendons at risk.
    This are nibbled away using a fine nibbler.

    The position of the lateral cutaneous nerve of forearm and suprficial radial nerve are checked in a full range of wrist and elbow motionThe nerves are allowed to sit in their normal position.
    An assessment is made about whether there is a risk of recurrent tether around the bone.
    There are a variety of techniques used to prevent nerves adhering to the bone or surrounding area. These are discussed elsewhere on Orthoracle.
    Moving the elbow and wrist demonstrates that the nerves are gliding well without residual scar tether and without coming into contact with the exposed surface of the radius.
    We have therefore decided against using any adjuncts here.
    The patient will undergo early mobilisation including a nerve gliding regime within the first post operative week.
    The sloops are removed and the wounds are irrigated with normal saline.

    The sloops are removed
    The tourniquet is also released and good haemostasis ensured.

    The wounds are irrigated with normal saline.

    A layered closure is performed with absorbable skin suturesThe subcutaneous layer is closed using a 3/0 monocryl.
    This is followed by a 4/0 monocryl running subcuticular suture.

    Soft dressings are applied
    The wounds are dressing with steristrips, an C-view non adherent dressing followed by a well padded wool and crepe dressing.
    The arm is placed in a Bradford sling.

    Post Operative

    Post operatively the patient is allowed to go home if pain is well controlled.
    The arm is kept in a Bradford sling for the next 48-72 hours.
    Oral analgesia is prescribed.
    The patient returns to a dressing clinic in 5-7 days for a wound check and some hand therapy to commence some early nerve gliding exercises.
    Desensitisation techniques aimed at the dysaesthetic area should be continued.
    At 2-3 weeks scar massage and desensitisation is commenced
    The patient is reviewed thereafter in the outpatient nerve clinic at 6 weeks post surgery.
    A further pain score is taken at this stage.

    Recommended Reading

    J Hand Surg Eur Vol. 2008 Apr;33(2):152-4. doi: 10.1177/1753193407087892.
    Neurolysis of the distal superficial radial nerve for dysaesthesia due to nerve tethering.
    Calfee RP1, Shin SS, Weiss AP.
    This study demonstrated moderate symptomatic improvement in patients with dysaesthesia following injury to the superficial radial nerve. The authors highlight difficulties correlating outcomes to intraoperative findings. The results are difficult to predict and not always satisfactory.
    Iatrogenic Injuries of the Palmar Branch of the Median Nerve Following Volar Plate Fixation of the Distal Radius.
    J Hand Surg Asian Pac Vol. 2017 Sep;22(3):343-349.
    Samson D, Power DM.
    This is one of a number of studies that highlight the vulnerability of cutaneous nerves during standard orthopaedic approaches to fixation.
    Iatrogenic nerve injuries in orthopaedics
    Journal of Musculoskeletal Surgery and Research; 2019 3(1):9-14
    Soh J, Hill J, Power DM
    An excellent review of iatrogenic nerve injuries in orthopaedics with a particular emphasis on examination and predicting outcome.
    Indications for implant removal after fracture healing: a review of the literature.
    Eur J Trauma Emerg Surg. 2013 Aug;39(4):327-37. doi: 10.1007/s00068-013-0283-5. Epub 2013 Apr 12.Vos DI1, Verhofstad MH2.
    This review demonstrates a wide disparity in practice for implant removal after orthopaedic surgery.

    Reference

    • orthoracle.com

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