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Hybrid tendon transfer and nerve transfer reconstruction of high radial nerve palsy

    Overview

    Learn the Hybrid tendon transfer and nerve transfer reconstruction of high radial nerve palsy surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Hybrid tendon transfer and nerve transfer reconstruction of high radial nerve palsy surgical procedure.
    Delayed presentation or failed reconstruction of a radial nerve injury results in a persistent wrist drop with paralysed digital extensors. Salvage options include a standard set of high radial tendon transfers, median to radial nerve transfers of or a combination of the two reconstructive modalities. The benefit of tendon transfer reconstruction for wrist extension is early recovery and improved digital function due to the tenodesis effect. The challenge with tendon transfers for digital extension is the loss of some end range wrist flexion due to the restriction conferred by the tendon crossing the wrist and the loss of finger independence at the MCPJ due to the composite action of the extensor tendon transfer reconstruction to all fingers. Some independence is achievable at the PIPJ and DIPJ with the activation of the hand intrinsic muscles through median and ulnar nerve innervation preservation.
    There is emerging interest in the use of nerve transfers to achieve better function, however the technique is technically challenging, has a 6-12 month delay until useful function is restored and the nerve transfer should be performed by 6-9 months from injury otherwise irreversible collapse of the intra-muscular neural plexus ensues. A hybrid reconstruction can be offered using a combination of pronator teres (PT) tendon transfer to the wrist and median to posterior interosseus nerve transfers using fascicles from FCR and PL in the proximal forearm. The approach to the proximal median nerve requires release of the PT superficial (humeral) head and so the hybrid technique involves formal elevation of the PT insertion to the radius in the identical way a traditional tendon transfer would be performed. This facilitates exposure of the median nerve and its motor branches in the forearm.

    Indications

    INDICATIONS
    High complete radial nerve palsy that has had no recovery and is too late for primary nerve reconstruction to result in useful function. Typically this would be greater than 6 months from injury with exploration identifying the injury at the spiral groove. At theis level reconstruction may provide BR and ECRL recovery but ECRB is uncertain and PIN function unlikely to recover.
    SYMPTOMS & EXAMINATION
    There is a wrist drop and no active extension of the fingers at the MCPJs and no retropulsion and extension of the thumb. Sensation is absent in the superficial radial nerve territory. There may be a Tinel’s sign at the site of injury and nothing distally. This indicates a high grade axonopathy with no evidence of neural regeneration and the likely surgical findings will be a rupture or a neuroma in continuity.
    IMAGING
    Imaging is seldom useful. The grade of nerve injury cannot be confirmed by ultrasound. Newer probes and MRI neurography sequences may help in identifying fascicle continuity in the future (distinguish a grade 1/2/3 Sunderlland from a 4/5 Sunderland) but the resolution is currently insufficient to make a diagnosis without surgical exploration. Low grade injuries can be watched but non-progressive low grades or high grades should be explored to define the injury segment.
    ALTERNATIVE OPERATIVE TREATMENT
    Reconstruction can be affected with a standard set of high radial tendon transfers. Typically PT to ECRB, FCR to EDC and PL to EPL would function well for most patients. The recovery time is short and the splint time limited to 6 weeks. Independence of finger extension at the MCPJ is not possible due to the mass effect of the tendon transfer. There is usually a loss of dome wrist flexion due to the FCR to EDC routed dorsally. The reconstruction can be performed with just nerve transfers. FDS branches can be transferred to the motor branch to ECRB. The nerve transfer option takes 6-9 months for reinnervation and 12-18 months for useful function. There is no need for splintage but this is a big time investment for patients. A hybrid technique as proposed here has splintage of the tendon transfer for 6 weeks and then useful tenodesis action allowing passive digit extension with active wrist flexion due to tightening of the extensor tendons. This will function well and assist in relearning the nerve transfer when it starts to work from 6 months.
    NON-OPERATIVE MANAGEMENT
    Patients can be provided with wrist splints plus gloves and possibly an glove with a passive extension assist mechanism. This should only be recommended if the diagnosis of radial palsy is early, clinically it looks like a low grade (neurapraxia or Sunderland 2-3 axonopathy) and recovery is anticipated.
    CONTRAINDICATIONS
    Patients should consent to the procedure and be aware of alternative treatment options. The hybrid tendon – nerve transfer is not well-reported in the literature and the results of tendon transfers alone are very good. There must be a perceived functional benefit from finger MCPJ extension independence to justify this approach and the additional time required for functional restoration.

    Setup

    The patient has a general anaesthetic without paralysis or a regional anaesthetic block at the axillary level without distal top up which could prevent the necessary stimulation needed to confirm anatomy and proceed with the nerve transfer. This case was combined with a radial nerve exposure under general anaesthesia without a tourniquet and the nerve gap was reconstructed with AVANCE processed nerve allograft plus an autologous sensory nerve graft to the branch to brachioradialis. The grafts are presented elsewhere on OrthOracle for brevity. This case study will concentrate on the hybrid PT to ECRL tendon transfer and the FCR/PL nerve branch transfer to the PIN.
    The WHO checklist is completed.
    A pneumatic tourniquet is useful for the exposure f the proximal median nerve and its branches because the area is vascular and any bleeding may compromise the view of the fine nerve ranches and risk inadvertent injury.
    A lead hand is useful to control the forearm rotation during mobilisation of the P~T (pronation) and dissection of the nerve branches (supination).
    Basic hand instruments, tendon instruments including weavers, microsurgery instruments, fibrin glue and an operating microscope are all required for this procedure.
    The patient is positioned supine with an arm board under the arm to be operated.

    Operation – 1

    The limb is prepped and draped exposing the whole arm below the axilla. A sterile tourniquet can be used for the initial exposure. Longer than 30 minutes of ischaemia renders the intra-operative nerve stimulation unreliable and if the dissection takes longer than this, I would recommend tagging the key nerve branches using colour coded sloops and then releasing the tourniquet for 10 minutes and then repeating the nerve stimulation. the skin incision is marked with a lazy “s” extending from the medial elbow over the neurovascular bundle at the antecubital fossa, distally to the dorsosradal aspect of the forearm.

    An Esmark bandage is used for exsanguination after prepping and draping to minimise the tourniquet time before nerve stimulation. Using a non-sterile pneumatic exsanguinator would result in an additional 5 minutes of ischaemia by the time the limb is prepped and draped in readiness for the skin incision.

    A lead hand can be used to support the arm to control rotation.
    The marked skin incision is incised and the wound deepened through the subcutaneous fat looking in the radial wound for the lateral cutaneous nerve of the forearm (LCNF) branches in close proximity to the cephalic artery.

    Bipolar cautery is used to coagulate small veins crossing the nerve (LCNF) and its branches.

    The dissection proceeds with Jamieson scissors to expose the nerve and release fascial bands overlying it.

    The LCNF is identified and a 90 degree tipped Mixter forceps is passed deep to it in preparation for passing a surgical rubber loop.

    A blue sloop has been passed under the LCNF.

    The LCNF is gently retracted using the blue sloop. This allows sufficient tension allowing brnach points to be seen in the fat so that the distal neurolysis can be safely accomplished.

    The muscle tendon junction of the brachioradialis (BR) is identified at this level with the extensor carpi radialis longus (ECRL) tendon seen dorsal to this. The fascia along the BR is incised.

    The pronator teres (PT) is identified passing to the radius deep to the BR.
    The radial artery (RA) and venae commitantes are running parallel to the BR on the volar border.
    The flexor carpi radialis FCR) is seen in the ulnar part of the incision.

    The dorsal part of the BR tendon is released form the overlying fascia. Note that the superficial radial nerve (SRN) passes from through this plane in the distal third of the forearm and care should be taken to avoid injury to the nerve.
    Even with a dense radial nerve palsy there may be some sensory recovery following proximal reconstruction and avoiding a second injury is essential.

    The BR tendon is now lifted with a Ragnall retractor and the SRN is seen deep to the tendon passing dorsally.
    The LCNF is retracted volarly. Care should be taken to avoid injury to the LCNF which is still functioning and provides sensationto the volar distal forearm and sometimes overlaps with the SRN territory which in this case is numb due to a complete high radial nerve rupture that has been debrided and grafted at the humeral level.

    The ECRB tendon is identified and mobilised and tagged in preparation for the tendon transfer from PT later in the procedure.

    Tension on the tendon distinguishes it from the ECRL which inserts to the second metacarpal base and has a radially deviating action on the wrist.

    The ECRB inserts into the base of the third metacarpal and had a central extensor action on the wrist.

    The recipient ECRB tendon is tagged with a white sloop.

    The ECRB is tagged.

    The ECRL tendon is in the yellow sloop.

    The BR, ECRL and ECRB are retracted dorsally to expose the pronator teres (PT) tendon insertion on the radius.
    The LCNF is in the blue sloop.

    The PT has a broad insertion to the radius in the mid forearm.
    The LCNF is retracted volarly and lies near the radial artery and venae comitantes.

    The PT is harvested from the radius with sharp dissection taking a sleeve of distal periosteum to provide a robust piece of tissue for suturing to the ECRB for the tendon transfer.

    Sharpey’s fibres are released with the scalpel. Rotating the forearm into mid pronation assists the tendon elevation.

    The volar distal component of the PT insertion is now elevated with the forearm in supination.

    The distal PT is elevated and tension provided with a clip or tendon weaver as the dissection proceeds in a proximal direction.

    The dissection continues proximally to mobilise the muscle belly in continuity with the tendon of the PT.

    Operation – 2

    The proximal PT must be mobilised at the level of the muscle belly to maximise excursion after transfer.
    The Langenbeck retractor is pulling the PT ulnarwards to facilitate exposure of the deep fascial coverings of the median nerve in the proximal forearm.
    The LCNF is retracted radially in the blue sloop.

    The fascia has been released and a Mixter has been passed deep to the median nerve to pass a sloop around it. Care should be taken to avoid injury to the proximal motor branches to PT and to FCR/PL that lie alongside the main trunk at this level in the loose fatty tissue.

    The median nerve lies in the red sloop. The fascial layers around the median nerve are being decompressed using Jamieson scissors.

    The sectioned PIN is reflected distally and in an ulnar direction and positioned on a microsurgical background material to aid visualisation during the microscope assisted co-aptation.
    The white sloop is around the FCR/PL fascicle group and motor branches from the median nerve that will be used to transfer to the PIN.

    The external neurolysis continues along the course of the median nerve in a proximal to distal direction to minimise the risk of inadvertent injury to motor branches.

    Lifting the median nerve in the red sloop provides gentle tension and the proximal motor branches can be demonstrated readily.

    Nerve stimulation is used to confirm contraction at normal thresholds and to assist in defining the anatomy of the branches.
    This stimulation is on the anterior interosseus branch from the median nerve which exits the nerve on the radial side.
    FDS – The flexor digitorum superficialis arch

    An FDS motor branch is being stimulated and the contraction of the muscle can be seen in the wound and the flexion of the digits can be seen in the hand.
    A normal nerve will stimulate at a threshold of 0.1-0.2mA. Poor stimulation may be seen after concomitant nerve injury, excessive intra-operative handling, retraction or long tourniquet times after approximately 30 minutes. If there is any doubt the tourniquet should be released and the stimulation assessment repeated after 15 minutes reperfusion of the limb.

    The yellow sloops are around the median nerve and the AIN. These nerves are critical and will not be used for nerve transfer.
    The red sloop is around the whole of the median nerve proximally before branching.

    On the ulnar side of the median nerve there is another motor branch identified. A Mixter is passed deep to it and a white sloop is being passed under the branch.

    Nerve stimulation will be used to confirm the anatomy of this branch. This is a branch to PL and FCR. It will be used for the transfer.

    A proximal interfascicular neurolysis of this branch using serrated microsurgery scissors allows sufficient length and mobilisation to be gained for subsequent nerve transfer with a tension free co-aptation.

    Radial to the median nerve the proximal PIN must be exposed and decompressed.
    There is a large vessel leash that crosses the interval from the common interosseus vessels to the mobile wad muscles and this leash must be moobilised and meticulous haemostasis achieved using medium ligaclips.

    The closed jaws of the scissors are used to lift the vessel away from the deeper structures to allow access with the clip applicator to apply the ligaclip.
    The LCNF is in the blue sloop. The Superficial radial nerve must be identified in this interval deep to the vessels and traced proximally to allow identification of the distal radial nerve trunk and the subsequently the PIN. The branch to ECRB will have a variable origin and lies in this interval and should be protected.

    The SRN is identified in the interval and a Mixter passed in preparation to pass a sloop.
    The white sloop remains around the potential donor nerve fascicle from the median nerve.

    Proximal external neurolysis of the SRN allows exposure. The branch to ECRB will be close by and great care should be taken to avoid inadvertent injury to this branch. In this case it is non-functional and the PT will be transferred to the ECRB, but it is possible to also undertake a nerve transfer to ECRB using FDS branches from the median nerve and perform the PT to ECRB tendon transfer insitu, allowing subsequent further improvements in wrist extension through successful reinnervation of the ECRB.

    The ECRB branch is identified and a Mixter passed in readiness for a sloop.

    A red sloop is placed around the motor branch to ECRB. The blue sloop remains on the LCNF and the yellow sloop is retracting the superficial radial nerve.

    The ECRB motor branch is retracted in an ulnar direction and the vessels at the proximal supinator muscle are identified and cauterised with bipolar diathermy.

    The PIN is identified as it passes distally between the two heads of the supinator muscle.

    A white sloop is passed under the PIN.
    Branches to supinator can be seen arising from the nerve in the red sloop.

    The superficial (humeral) head of the supinator is released and the PIN can be seen entering the supinator tunnel.

    The PIN is sectioned proximally after stimulation confirms no function. In this case there was a high energy injury to the proximal radial nerve with a large gap that was reconstructed with AVANCE processed nerve allograft as a pain management strategy, The injury was referred late and it was deemed unlikely to result in meaningful motor recovery and so the distal reconstruction was undertaken to try and restore motor function to the digital extensors and ECU using a nerve transfer technique.
    Nerve transfer is performed close to the denervated muscles resulting in rapid reinnervation that can provide a successful functional recovery even in late presenting cases such as this where proximal reconstruction would not guarantee distal functional recovery.
    When sectioning nerve for transfer the neurolysis should be completed prior to sectioning to avoid unnecessary handling of the nerves. The site of transfer should be estimated and the sites of neurotomy of donor and recipient should be selected to allow a tension-free co-aptation as close to the recipient muscle as possible.
    Sectioning should be using the mantra “donor distal and recipient proximal”. The co-aptation should be using the mantra “donor distal, recipient distal to facilitate earlier reinnervation.

    The donor fascicles are sectioned as distally as possible.

    The donor and recipient nerves are placed on the background and trimmed to provide a clean cut at the co-aptation site.

    Operation – 3

    After trimming of redundant connective tissue there is a good size match of the donor and recipient nerve fascicle groups.

    The nerve transfer is ready for microscope assisted co-aptation.

    An operating microscope is used for the nerve suture to ensure good suture placement without distorting the fascicles.

    The nerve transfer is approximated with 9’0 nylon interrupted sutures. Between 2 and 4 sutures are typically used in this transfer.

    Passing the 9’0 nylon suture needle.

    Tying the knot in the 9’0 nylon suture at the co-aptation site.

    A second suture is placed at the co-aptation site.

    The completed neurorraphy with 2 well placed equatorial sutures.

    Tisseel fibrin glue is used to seal the co-aptation site and provide additional strength for the first 2 weeks.

    Tisseel has 2 components, one a protein and the second the activator. A fibrin clot forms at the site of activation. The Tisseel is pre-prepared in a syringe and is frozen. It is defrosted in a warm water bath prior to use.

    The Tisseel is placed circumferentially around the co-aptation site and the microsurgical background material can be rolled around the transfer to provide full cover during activation. This ensures a robust support around the co-aptation site.

    The completed Tisseel support prior to removal of the microsurgical background material.

    Additional Tisseel can be used to support the nerve transfer to the adjacent tissues to help dissipate traction forces across the co-aptation site. The forearm and elbow should be cycled through a full flexion-extension and pronation-supination cycle to ensure that there is do undue tension on the nerve transfer.

    The wound is closed proximally to protect the nerve transfer while the tendon transfer PT to ECRB is performed in the distal wound.

    The PT is mobilised and a clip used to provide tension.
    The wrist is extended to optimise the tension at the transfer site.
    The elbow is flexed 30 degrees.

    Whilst maintaining the elbow and wrist position the tendons are sutured. In this case a running cross suture side-to-side tenorraphy is performed using a 3’0 PDS suture.

    The tendons are laid on each other and the PDS suture is placed proximally between the two tendons.

    Tension on the PT distal end is maintained by the assistant who also keeps the position of the elbow and wrist that the operator has defined.

    The first suture is tied and then it will be used to provide the running suture along the edges of the two tendons.

    Sufficiently large bites should be taken to ensure that the repair is robust.

    The tendon suture continues with the predetermined wrist and elbow position maintained.

    Both the ulnar and radial sides of the tendons need suturing. Once the suture is completed in one direction the suture is locked and continued back in a cross-stitch configuration. This ensures a robust repair that can allow more rapid supervised mobilisation. The wrist extension position will be maintained by cast initially and later through thermoplastic splints.

    The wound is closed in layers. The fat is approximated with 4’0 vicryl avoiding injury or tether of the LCNF which has intact sensation.

    Completing the sub-cutaneous closure.

    Staples are applied to the skin edges.

    Operation – 4

    Local anaesthetic infiltration to the skin edges.

    This operation followed on from a proximal radial nerve exposure and allograft reconstruction that is featured elsewhere on OrthOracle. The proximal wound is dressed with Mepitel. pressure is maintained on the distal wound as the tourniquet around the upper arm is released to facilitate dressings and cast application. The radial nerve reconstruction was performed without a tourniquet. A sterile tourniquet was applied for the nerve exposure in the forearm.

    Dressing the upper arm wound.

    Dressing the forearm wound.

    Gauze padding and then a wool bandage is loosely applied in preparation for the plaster of Paris Volar slab.

    The cast is applied to the level of the metacarpal necks in the hand and is moulded to the palm. It should not prevent active digital flexion. The reconstruction to digit extension is through nerve transfer. There is no need for extension immobilisation of the digits which would be required if tendon transfer was used for this function instead.

    The cast is moulded to the arm and hand maintaining wrist extension.

    An above elbow extension is used to fully immobilise the PT and the ECRB. This will provide good pain relief through splintage of the limb for the first two weeks post-operatively. After the wound is reviewed and clips removed a below elbow immobilisation with wrist extension can be used for four additional weeks.

    Post Operative

    The limb is elevated and analgesics are prescribed.
    The arm should be monitored for bleeding and swelling and the patient can be discharged when comfortable. Using regional blocks and performing surgery on a single limb rather than autologous nerve grafting from the sural nerve under general aaesthesia may allow earlier patient discharge.
    The wound should be reviewed at 2 weeks and the clips removed.
    A below elbow thermoplastic splint is then applied for 4 weeks more.
    At the 4 week post-operative point a hand therapist can assess the patient and commence isometric contraction of the transferred tendon with the wrist supported in extension.
    Exercises progress with introduction of active extension with gravity eliminated through mid rotation positioning of the forearm.
    Anti gravity motion is commenced as the patient progresses from 6-12 weeks post-operatively.
    The nerve transfer will take 3-6 months to reinnervate and the patient should be taught composite wrist flexion finger extension tenodesis type activity with guided motor imagery to assist in rehabilitation of the nerve transfer.
    The Birmingham nerve transfer rehabilitation protocol has 6 stages.
    The earliest sign of reinnervation is deep muscle tenderness on squeezing the recipient muscle. This is followed 6 weeks later by visible contractions. At this stage strengthening is necessary before exercises to imporve cortical plasticity and finally functional training.

    Recommended Reading

    There are many factors that affect the outcome from a peripheral nerve reconstruction including severity of the injury, delay to reconstruction, adequacy of debridement, method of reconstruction, tension in the reconstruction, distance of the denervated targets from the injury site and patient factors including age and co-morbidities.
    The gold standard for reconstruction of a critical nerve gap is reversed autologous sensory nerve graft. The sural nerve is typically harvested for a main nerve trunk with a gap of 5cm or more due to the need for 3-5 cables (a total of 25cm of nerve). The sural nerve has little donor site morbidity but necessitates general anaesthesia. There are sall risks of painful neuroma at the proximal donor harvest site plus risks or DVT, PE and donor site infection. The balance of risk and benefit should be weighed for each patient.
    There is an abundance of data on AVANCE allograft utilisation and safety from medical publications and from the RANGER registry study in the USA. The efficacy data is strong for digital nerves and the numbers of sensory nerves and mixed motor-sensory nerves are smaller currently. Comparative data from autologous versus allograft reconstruction is limited. As such my practice is to use allograft in cases of pure sensory nerve reconstruction in otherwise sensitised individuals (neuroma reconstruction) where there is a significant risk of donor site sensitisation; in cases where there is another viable motor reconstruction (distal motor nerve transfer) and reconstruction is for pain, sensory recovery and no-critical motor recovery; in cases where there is insufficient autologous nerve available; in cases where recovery is unlikely but the prime objective is pain management; contraindications to general anaesthesia or lower limb surgery; failed primary autologous graft reconstruction and in cases where patients choose this technique.
    NICE, the national institute for health and care excellence in the UK have issued guidance on the use of processed nerve allograft in nerve repair: NICE Interventional Procedure Guidance: 597 (www.nice.org.uk/guidance/ipg597).Enhanced governance arrangements and audit of outcomes is recommended for use outside sensory digital nerve in the hand. A summary of the guidance and the published literature is provided below.
    AVANCE processed nerve allograft is provided frozen in a number of sizes and the appropriate graft can be selected after debridement and defining the nerve gap.
    This patient had the radial nerve gap reconstructed with AVANCE processed nerve allograft and autologous graft from the posterior cutaneous nerve of the forearm.
    The late presentation, large gap and older patient make successful distal recovery unlikely and so a hybrid tendon and nerve transfer distal reconstruction was adopted. The nerve transfer to the digits allows independent MCPJ extension and the PT to ECRL provides useful early functional wrist extension which can assist a tendodesis digit extension action with wrist flexion.
    Nerve transfers may be used for wrist extension with FDS branch transfer to the nerve to ECRB. The procedure is rarely performed because of the early robust results of tendon transfer and the technical challenge of undertaking a nerve transfer which does not fall in the repertoire of many hand surgeons.
    References for median to radial nerve transfers:
    Mackinnon SE, Roque B, Tung TH. Median to radial nerve transfer for treatment of radial nerve palsy. Case report. 2007 Sep;107(3):666-71
    Ray WZ, Mackinnon SE. Clinical Outcomes following median to radial nerve transfers. J Hand Surg Am. 2011;36(2):201-208

    Reference

    • orthoracle.com

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