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Sural nerve graft reconstruction of the sciatic nerve after resection of a malignant peripheral nerve sheath tumour

    Overview

    Learn the Sural nerve graft reconstruction of the sciatic nerve after resection of a malignant peripheral nerve sheath tumour surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Sural nerve graft reconstruction of the sciatic nerve after resection of a malignant peripheral nerve sheath tumour surgical procedure.
    Autologous reversed sural nerve cable grafting is the gold standard method for reconstruction of large nerve gaps in mixed (motor and sensory) major nerve trunks. Functional recovery is determined by the gap length, the site of the reconstruction, the duration of denervation, the surgical graft bed, the quality of the target muscles and the age of the patient. Malignant peripheral nerve sheath tumours (MPNST) are rare and usually present with a rapidly enlarging and painful mass with associated sensory and motor deficits. There may be a history of a neurofibromatosis which is associated with malignant transformation in peripheral nerve sheath tumours. Magnetic resonance imaging and biopsy are used to determine the diagnosis. The pathophysiological grade and the stage of disease determine the prognosis. Staging computed tomography will identify whether there are any metastases at presentation.
    The surgical management involves excision of the tumour with a cuff of normal tissue to achieve an adequate surgical margin. Whilst the exact width of an adequate margin remains a sourc of constant debate, it should take into consideration the histological subtype, the quality of the margin tissue, the proximity of nearby vital structures and the use of adjuvant or neo adjuvant radiotherapy. In the case of large tumours and high grade histologies, compartment excision or ablative surgery may need to be considered to achieve an adequate margin. When post-operative radiation is required, non-vascularised autologous graft reconstruction is unlikely to support useful neural regeneration. In lower grade tumours, gap reconstruction with autologous graft provides a scaffold for nerve regeneration and results in less neuropathic pain, some proximal motor recovery and the chance of protective sensation to the plantar surface of the foot. Biopsy may lead to sampling error and the final grading of the tumour and adequacy of excision can only be determined on final specimen histopathological examination.
    The case presented is a Malignant peripheral nerve sheath tumours that was biopsied and reported as low grade and surgical excise and bilateral autologous rural nerve cable grafting performed for gap reconstruction. The technique presented here will focus on the grafting technique and alternative options.
    The tumour resection and discussion of the decision-making process for tumour management is covered in brief here but is covered in more detail with a technical description on OrthOracle at:
    Excision of soft tissue Sarcoma ( thigh)



    Indications

    INDICATIONS
    Malignant peripheral nerve sheath tumours (MPNST) are rare and typically present as painful enlarging masses in peripheral nerves. They may be sporadic or associated with neurofibromatosis. There is frequently a neurological deficit depending on the nerve of origin and the site of tumour involvement. Surgical resection is the primary treatment and the resultant nerve gap may be reconstructed with autologous nerve graft for the management of nerve pain and potentially to restore some motor or sensory function to the affected limb.
    A biopsy is performed to identify the tumour type and grade. Staging considers the tumour size, grade and whether metastases are present on imaging.
    Grading
    Low-grade means the cancer cells are slow-growing, look quite similar to normal cells, are less aggressive, and are less likely to spread
    Intermediate-grade means the cancer cells are growing slightly faster and look more abnormal
    High-grade means the cancer cells are fast growing, look very abnormal, are more aggressive and are more likely to spread
    Staging
    Staging is defined as local or systemic and defines the degree of tumour involvement on the whole patient. Local staging is dependant on cross sectional imaging of the tumour and histological assessment of biopsy material. Systemic staging is defined as identification of metastatic disease. Staging takes into consideration the size, depth and histological activity of the tumour, and the presence of metastatic disease. Tumours are classified histologically as low grade, intermediate grade or high grade depending on the degree of differentiation, mitotic activity and nuclear size. Soft tissue sarcomas are classified as superficial or deep depending on their relationship to the deep fascia. Common sites of metastatic disease include the lungs though certain histological variants can metastasise to other areas including other soft tissues, bone and liver.
    Surgery to resect the tumour results in neurologic deficit which is usually permanent. In all cases, the aim of surgery is to achieve local control of the tumour by its complete removal with an adequate margin. This has been shown to reduce the risk of local recurrence though the effect of local recurrence on overall survival is less clear. Where complete removal of the tumour can be achieved with limb salvage surgery, the effect on function of the limb should also be taken into consideration when planning surgical excision.
    SYMPTOMS & EXAMINATION
    There is usually a large mass in the line of a peripheral nerve with distal motor sensory and /or motor dysfunction. There is usually neuropathic pain and there may be a Tinel’s sign elicited when tapping over the tumour. The pain or paraesthesia that is indicative of a positive Tinel’s sign is felt in the cutaneous territory supplied by the affected nerve.
    IMAGING
    Magnetic resonance imaging is the preferred method of cross sectional imaging. This allows accurate initial characterisation of the tumour and allows local staging. MR allows planning for final surgical resection highlighting the tumour proximity to vital structures as well as accurately detailing the structures involved and affected by the tumour.
    Computed tomography (CT) of the chest, abdomen and pelvis is used for tumour staging to identify any metastases at presentation. In certain histological variants (eg myxoid liposarcoma) which can metastasise to atypical locations, whole body imaging in the form of whole body MRI or PET-CT may be used.
    ALTERNATIVE OPERATIVE TREATMENT
    The standard method of treatment involves a biopsy to define the grade of the tumour and combined with the imaging findings may be used to decide on whether pre-operative radiotherapy is required. Surgical options depend on the site, size, grade, functional deficit and potential morbidity of surgery. Surgery can involve simple tumour resection, compartment excision or amputation. The decision to reconstruct the nerve gap is a complex one and a peripheral nerve specialist should be involved in the discussion with the patient and the multidisciplinary oncology team. Gap reconstruction with non-vascularised autologous graft is the gold standard in gaps up to 70mm. Longer gaps are controversial as there is little evidence that useful motor or sensory recovery returns. The option for autologous graft should be carefully considered when post-operative radiotherapy is planned. Staged reconstruction could be considered, however there is the added challenge of surgery in a scarred bed with poor vascularity. The sural nerve has a significant connective tissue component and only approximately 30% of the cross-sectional area is comprised of endoneural tubes. Due to the length available and the relatively minor morbidity with sensory loss around the lateral border of the heel and foot, it is the preferred site for autologous grafting when large lengths are required. There are other sites that may be preferred for small gaps and in the upper limb operating on a single limb under regional anaesthesia may be preferable and so a cutaneous medial or lateral arm or forearm nerve may be selected. The risk of donor site neuroma at the proximal stump is low and the published evidence supports 2-5% as being a typical rate. An alternative is to consider using processed nerve allograft which avoids the donor site cost to the patient. It is a useful strategy when the gap reconstruction is aimed at reducing neuropathic pain and functional recovery is considered unlikely. For essential motor nerves, the option of a distal motor nerve transfer for a critical function or a sensory transfer for protective sensation should bee considered, however they are often not available. In this case of sciatic nerve resection there are no remaining motor nerve transfer options for function below knee.
    Autologous nerve transfer was planned due to pre-existing neuropathic pain and biopsy demonstrating low grade MPNST and so no adjunctive radiotherapy was planned, assuming surgical resection margins are adequate.
    NON-OPERATIVE MANAGEMENT
    Multi modal treatment for soft tissue sarcomas remains the mainstay of treatment combining surgical resection with adjuvant or neo adjuvant radiation therapy. Contraindications to surgery are largely limited to patients in whom surgical excision would carry a significant risk of peri operative mortality, or those in whom resection of the primary tumour will not result in cure eg patients with advanced metastatic disease. For patients in whom the risks of surgery or the functional detriment outweigh the potential of gaining local control (eg patients with small volume metastatic disease where tumour excision will result in significant functional detriment), isolated limb perfusion may be considered. ILP relies on isolation of the limb vascular circulate and infiltration of chemotherapy agents at high doses int the affected limb. This has been shown to produce high rates of local tumour control without the functional detriment of surgical excision or ablative limb surgery.
    CONTRAINDICATIONS
    A relative contraindication to nerve gap reconstruction with autologous nerve graft after MPNST resection is planned post-operative radiotherapy or extensive compartment excision where no useful functional recovery is likely. Long gaps are also unlikely to provide useful functional recovery. In such cases surgical reconstruction with grafts is primarily offered to reduce post-operative neuropathic pain.

    Setup

    The patient is counselled regarding the diagnosis, the risks of surgery and the morbidity of nerve resection balanced against the increased survival. The MRI is used to plan the tumour resection margins and estimate the resultant nerve gap for reconstruction. In this case the gap was estimated at 150mm and therefore both sural nerves would be needed to provide sufficient cables for bridging the nerve gap.Under a general anaesthetic the patient is placed prone on the operating table under general anaesthesia. A tourniquet is placed on the contralateral thigh to reduce blood loss during sural nerve harvest from the normal leg. ~No tourniquet was used on the side of the tumour due to the site of tumour in the mid to lower thigh.
    The surgical resection was performed by a team of specialist orthopaedic oncology and peripheral nerve reconstruction surgeons. The oncological procedure and decision making will be covered separately in the oncology atlas of OrthoOracle.
    Two sets of surgical instruments are required with a change or instruments gowns and gloves after tumour resection and application of orientation sutures. This is to prevent tumour contamination to other surgical sites. The nerve reconstruction requires loupe magnification, a mister and surgical rubber loops for donor nerve graft mobilisation and dissection, micro instruments, fine 8’0 and 9’0 sutures and Tisseel tissue glue. The autologous nerve grafts are inserted with microscope magnification.

    Operation – 1

    T1 weighted sagital MRI demonstrating the mass arising within the sciatic nerve. The nerve above and below the lesion can be seen. The lesion demonstrates a heterogenous high signal matrix typical of a malignant lesion.

    T1 weighted axial image again demonstrating the lesion within the sciatic nerve.

    The patient is placed prone under general anaesthesia on a Montreal mattress with the left thigh tumour site marked.The tourniquet is placed around the right thigh but not inflated. The patient is padded and the arm raised with shoulder abduction and external rotation. There is mild calf wasting from sciatic nerve dysfunction and disuse atrophy secondary to nerve pain.

    The patient has an underlying genetic diagnosis of neurofibromatosis type 1 with multiple cutaneous lesions and cafe au lait skin pigmentation patches.
    The surgical incision is marked with a planned excision of the biopsy tract in continuity with the tumour as part of the surgical exposure.

    Both lower limbs are prepped and draped.The tourniquet on the right thigh will only be inflated for the contralateral sural nerve graft harvest.

    The tumour is large and can be readily seen in the lower posterior left thigh. The tumour is firm and mobile only in the transverse plane, in keeping with its location in the longitudinally aligned sciatic nerve trunk.

    The skin is incised and the posterior cutaneous nerve of the thighs’ terminal branches may be seen and should be protectedThe skin is incised and monopolar diathermy is used to dissect to the deep fascia. There is no tourniquet on the left leg and so meticulous haemostasis is needed to minimise blood loss and maintain a bloodless field. The posterior cutaneous nerve of the thighs’ terminal branches may be seen and should be protected as it may be possible to preserve this nerve as it exits above the planned upper sciatic nerve resection level.

    The skin has retracted and the deep fascia is seen with the bulging of the posterior compartment muscles due to the tumour deep to them. The biopsy tract has been circumscribed and remains in continuity with the underlying tumour.

    The deep fascia is opened and the interval between the medial and lateral hamstring muscles is identifiedThe fascia is opened and the interval between the medial and lateral hamstring muscles is identified and developed. The broad Langenbeck retractor is placed in the upper interval.

    A Norfolk and Norwich retractor is placed in the interval between the medial and lateral hamstring muscles.This allows visualisation of the plane, identification of the nerve beneath and enables distal dissection and development of this plane. Caution around the mid incision point ensures that the skin excision of the biopsy tract will remain in continuity with the tumour in the final histological excision specimen.

    The sciatic nerve is identified in the upper wound above the tumour.SN – sciatic nerve
    ST/SM – semitendinosus / semimembranosus
    BF – biceps femoris
    MPNST – malignant peripheral nerve sheath tumour
    BT – biopsy tract
    The sciatic nerve is identified in the upper wound above the tumour.
    On the medial side of the tumour at its midpoint the popliteal artery emerges from Hunter’s canal. There was a clear layer between the tumour and the vessel on the MRI scan and so vessel preservation was planned and possible to achieve.

    At the distal end of the tumour the dissection in the popliteal fossa identifies the tibial nerve, the common peroneal nerve and the popliteal vessels.

    The MPNST is mobilised away from the vessels and the sciatic nerve origin is now clearly defined.

    The upper sciatic nerve is sectioned at least 5cm above the macroscopic tumour extent.A scalpel blade provides clean sectioning without crushing the fascicles. There is usually a large longitudinal vasa nervorum that will need haemostasis.

    The nerve section is completed in the sciatic nerve above the MPNST.

    A gap forms immediately on sectioning the nerve due to tensegrity (tension integrity or the intact nerve). This means that the effective gap for reconstruction will be longer than the planned length of sciatic nerve resection for tumour clearance.

    Careful coagulation with bipolar diathermy to the cut sciatic nerve faceThe proximal cut sciatic nerve face is bleeding with a large vessel that needs coagulation with bipolar diathermy. Great care should be used and magnification to ensure that there is no damage to the adjacent nerve fascicles.

    The healthy proximal fascicle structure is clearly seen on the cut face of the proximal sciatic nerve stump.

    The distal tibial nerve and common peroneal nerves are also sectioned with a scalpel blade.

    The resected tumour is tagged with orientation sutures to enable the histopathologist to define adequacy of resection margins.There was a clear plane between the popliteal vessels and the distal half of the tumour at the level of the upper popliteal fossa and the tumour was dissected from the vessel leaving an intact fascial layer over the tumour. This was the site of a planned minimal resection margin.

    Next the surgical team change gown and gloves and open new instrumentation for the next phase of the surgery which involves opening sural nerve donor sites in both lower legsThe wound is irrigated and swabbed with meticulous haemostasis. . This strategy aims to reduce the risk of tumour seeding to new surgical sites.

    The right leg is flexed at the knee and the calf squeezed for exsanguination. The right thigh tourniquet is inflated.

    An Esmarch bandage can be used for exsanguination, however squeezing the calf is sufficient prior to elevating the thigh tourniquet.

    The sural nerve is identified midway between the posterior aspect of the lateral malleolus and the achilles tendon at the level of the ankle. It lies alongside the short saphenous vein which is usually visible when there has been limited exsanguination. A Mister forceps can be passed deep to the nerve to receive a surgical sloop that facilitates dissection without excessive handling of the nerve.

    The blue sloop is placed around the sural nerve.

    Operation – 2

    Dissection continues to separate the nerve from the short saphenous vein. There are short crossing vessel tributaries that can be coagulated with bipolar diathermy and then divided with scissors.

    Once the sural nerve is identified the skin can be incised along the expected course of the nerve.The normal course of the sural nerve is a line from the deep fascia overlying the interval between the two heads of the gastrocnemius to the lateral ankle mid way between the posterior aspect of the lateral malleolus and the achilles tendon. The peroneal communicating nerve arises from the common peroneal nerve as it approaches the peroneal tunnel and has a variable course, joining the main sural nerve arising from the tibial nerve at between 5 and 20 cm below the popliteal fossa. A long personal contribution can be protected and dissected in addition to the main sural nerve trunk and used as an additional cable in the nerve graft reconstruction.

    The assistant continues with the right leg sural nerve harvest under tourniquet. The main surgeon exposes the sural nerve on the left leg which has had tumour resection.This exposure is undertaken without a tourniquet. Careful haemostasis should be performed throughout the dissection. The same anatomical landmarks are used for sural nerve exposure and dissection.

    The left sural nerve is tagged with a sloop and a self-retaining West retractor used to assist with nerve exposure.

    The sural nerve is mobilised away form the short saphenous vein using the sloop to minimise handling of the nerve during harvest. Excessive traction or instrument handling can damage the endoneural tube structure and prevent neural regeneration.

    An additional contribution from the common peroneal nerve is identified and dissected. It is measured with a ruler to establish whether it is of sufficient length to provide an additional cable graft for the sciatic nerve defect reconstruction without need for an additional neurorraphy.

    The sural nerve harvest continues to gain sufficient length for multiple cables to reconstruct the sciatic nerve gap.

    As the dissection continues of the left leg the low formation of the sural nerve is identified and both of these nerves will be harvested as cable grafts.
    The nerves are thrn sectioned and marked at the proximal end to allow confirmation of orientation for reversal placement during nerve grafting.
    The nerve is placed in a saline soaked swab and kept in a dish on the scrub trolley with the contralateral nerve when harvest is completed.

    The left leg has adequate haemostasis confirmed and then the wound is closed with interrupted absorbable sutures.

    Partial closure of the sural graft harvest wound on the left leg.

    The deep closure is completed prior to subcuticular closure.

    The sural graft donor length is maximised on the right leg prior to sectioning and removal of the graft.

    The left leg sural harvest site subcuticular closure is completed with a 3/0 monacryl suture and steristrips.

    Nerve instrumentation is opened in preparation for the cable nerve graft implantation. The instrumentation includes jeweller’s forceps, curved needle holders and curved serrated nerve micro scissors and straight micro suture scissors.

    A rubber background is placed under the proximal sciatic nerve stump to reduce blood pooling at the site of microsurgical neurorraphy and to prevent nerve graft adherence to the surgical bed through fibrin clot formation.

    The sural nerve graft is reversed to prevent axonal escape of regenerating axons down side branches which have been sectioned during the harvest.

    The sural nerve is inserted as a series of cables across the nerve gap connecting fascicle groups.It is not possible to accurately match fascicles due to the normal inter-fascicular branching along major nerve trunks that renders the fascicular pattern different at different levels. However, the nerve has a sector organisation and the dorso-lateral component feeds into the common peroneal nerve and the remainder the tibial nerve. This gross anatomy can be used to direct bundles of cabled sural nerve graft to the appropriate distal target. Each cable is sutured with 8’0 nylon using micro instruments. The length of nerve used is sufficient that there is no tension. Using cables in this way allows rapid revascularisation from the surgical bed due to the higher surface area to volume ratio.

    The cables are positioned to cover the proximal nerve stump and built up progressively.2-3 sutures at each end is usually sufficient if inserted without tension and supplemented by Tisseel glue.
    The operating microscope is used to enable accurate placement of the sutures in the epineurium of the sural nerve graft and to secure each cable to the perineurium of the target fascicle.

    6 cables are possible across the 150mm gap using both sural nerves and both peroneal communicating branches which were each of sufficient length with a low-forming connection with the main sural nerve to have two additional cables without inter graft neurorraphy.

    Tisseel tissue glue is applied and produces a fibrin clot around the coaptation sites and between the fascicles, providing support and resistance to disruption of the nerve-graft interface.Tisseel is provided ready-prepared and frozen. Simply defrosting in warm water for a few minutes is sufficient preparation. There are two syringes, one with the substrate and one the activator. The solutions mix in the nozzle tip and form the fibrin clot. The nozzle requires frequent changing due to becoming blocked with clot.

    Here the grafts are being “spot welded” using the Tisseel to allow ease of handling and resistance to disruption during performance of the distal neurorraphies.

    The distal neurorraphies are sutured and then Tisseel glue is used to provide additional support, as for the proximal neurorraphy.

    The completed neurorraphies with multiple cables of autologous sural nerve from the sciatic nerve to the tibial and common peroneal components of the nerve as they branch distally with sector orientation.
    The background material will be removed and more Tisseel placed around the distal cables.

    The completed nerve graft prior to closure.

    The muscle layer is opposed over the graft and secured with interrupted absorbable vicryl sutures.The muscle layer is opposed over the graft and secured with interrupted absorbable vicryl sutures.

    Operation – 3

    Drains have been carefully positioned remote from the graft and brought out proximal to the surgical wound. They must not be placed adjacent to the graft as they could cause disruption due to the vacuum or by adhering with fibrin and early scar and causing traction and disruption during drain removal.
    The subcutaneous tissues are closed with an absorbable suture.

    The wound closure is completed with skin closure with staples. The distal sural nerve graft harvest site from the same leg has been closed earlier with a subcuticular closure and steristrips.

    The completed surgery. Note the dressings on the right contralateral donor sural nerve harvest site. Dressings will be placed on the left operated leg with bulky support wool and crepe bandages.

    Bulky support wool and crepe bandages are applied to both legs.

    A knee extension splint on the left nerve grafted side prevents excessive knee movements. `the grafts are inserted in the position of extension with sufficient redundancy that there is no tension with knee extension and hip flexion.

    Post Operative

    The operated limb is protected in an extension knee brace too prevent excessive movement at the graft site. The foot of the bed is elevated to reduce swelling and observations to ensure no bleeding.
    The drains are left in for 72 hours or longer if continuing to drain more than 50mls per day. The dressings can be reduced at 10-14 days and clip and steristrips removed at 2 weeks.
    The patient can mobilise full weight bearing with crutches for support and using the extension knee brace for three weeks.
    Th patient should be monitored for neuropathic pain and consideration given to prescribing neuromodulatory therapy (Pregabalin, Gabapentin or Amitriptyline) which needs to be continued until neural recovery is established.
    The histopathology specimen will be examined and reported to ensure that resection margins are adequate and to confirm that the biopsy low grade atypia is correct. Sampling error can lead to an under estimate of grade and the final prognosis and subsequent need for adjuvant therapies rests on the histological analysis of the resected specimen.
    The approach to the tumour will be covered separately in the orthopaedic oncology atlas for OrthOracle. Here a brief summary of the oncology approach is added for completeness, although the focus is on the nerve graft reconstruction.
    Recovery in a nerve gap of this size is unpredictable. The immediate reconstruction in a relatively healthy bed with a controlled surgical trauma to the nerve may allow successful neural regeneration and outgrowth from the proximal nerve stump. However the distance for the axons to cross is challenging and sustained growth requires Schwann cells to survive within the graft or migration of Schwann cells to support the growing axons plus adequate revascularisation.
    Surgery is done in this case primarily to prevent an symptomatic end neuroma at the proximal stump, to reduce the risk of severe neuropathic pain and to hopefully gain some motor activity in the proximally innervated muscles in the lower leg. Distal motor reinnervation is unlikely duet the time-distance phenomenon. Nerve regeneration is approximately 1-1.5mm per day in acute reconstructions (although closer to 1 in the lower limb and when there are large gaps distant to the nerve cell body). Motor reinnervation has to be within 12 months if it is to be successful and typically this will allow growth of around 300mm with the early lag for up regulation and axonal transport delays from the cell body to the proximal neurorraphy site. The soleus, gastrocnemius and tibias posterior may partially reinnervate through the graft to the tibial nerve. The peroneus longus, brevis and tibias anterior could reinnervate from the common peroneal target grafts. Muscles beyond this are unlikely to regain any useful innervation. Trophic muscle stimulation physiotherapy can be used in such cases although the evidence is lacking. There is limited evidence that electrical stimulation creates stronger neurotrophism, faster and more sustained axonal regeneration. It cannot maintain motor activity in complete denervation lesson and is therefore less useful than in cases of spinal nerve root compression where there is some retained axonal activity in the affected root or perhaps other segmental innervation from adjacent roots that is unaffected. Whether is renders the muscle more responsive to incoming axons for longer remains to be proven.
    Sensory recovery can be sustained with axonal growth for longer, perhaps even 2-3 years. If successful there is the potential for some protective sensation to the sole of the foot.

    Recommended Reading

    Outcome assessment should be using the Medical research Council (MRC) motor grading system (M0-M5). However it should be noted that grade 4 encompasses a huge percentage of potential outcome range with virtually non-functional to virtually normal and is therefore of limited value. Absolute strength with myometry may be better and can be compared to the normal contralateral limb, however it doesn’t measure endurance and fatigue which requires more extensive assessments that may be time prohibitive.
    Sensory evaluation can be through the Sensory MRC scale using (S0, S1, S2 S3 S3+, S4)
    Pain VAS scale 0-100 is a useful and simple tool for measuring pain, however formal recording of a McGill Pain score can be useful as well as monitoring analgesic and neuromodulator use.
    Functional scores for the lower limb can be monitored but a patient specific goal-attainment score is useful for monitoring recovery and success following lower limb peripheral nerve reconstruction.
    Psychological evaluation and some measure of wellbeing are useful in evaluating patients with complex diagnoses and long follow-up periods. The SF-36 is a reasonable score which measures a number of domains and yet is relatively simple and quick to complete.
    References
    Hoben GM, Ee X, Schellhardt L, Yan Y, Hunter DA, Moore AM, Snyder-Warwick AK, Stewart S, Mackinnon SE, Wood MD. Increasing Nerve Autograft Length Increases Senescence and Reduces Regeneration. Plast Reconstr Surg. 2018 Oct;142(4):952-961
    This study in rats demonstrates that there is lower regeneration in longer grafts. This is mirrored in clinical studies where long grafts have poor clinical outcomes in mixed motor and sensory nerve trunks.
    George SC, Boyce DE. An evidence-based structured review to assess the resultsof common peroneal nerve repair. Plast Reconstr Surg. 2014 Aug;134(2):302e-311e
    This review of 1577 repairs of the common peroneal nerve demonstrated that later reconstruction of nerve gaps using autologous graft conferred lower rates of successful reinnervation and that larger gaps of 120mm or more had successful reinnervation of just 11% compared to 64% successful (>M4) in grafts less than 60mm.
    Miloro M, Stoner JA. Subjective outcomes following sural nerve harvest. J Oral Maxillofac Surg. 2005 Aug;63(8):1150-4
    This study demonstrated satisfaction rates from sural nerve graft donor sites that correlated with recipient site successful reinnervation in maxillofacial surgery.
    Hwang IK, Hahn SM, Kim HS, Kim SK, Kim HS, Shin KH, Suh CO, Lyu CJ, Han JW. Outcomes of Treatment for Malignant Peripheral Nerve Sheath Tumors: Different Clinical Features Associated with Neurofibromatosis Type 1. Cancer Res Treat. 2017 Jul;49(3):717-726
    95 patients treated for MPNDST. 52% 10 year survival. Survival for neurofibromatosis (NF) type 1 associated tumours was 45% and for sporadic tumours was 60%. The NF type 1 associated tumours were larger at presentation (82mm versus 50mm) and occurred in younger patients (mean 32 versus 45 years).
    Stucky CC, Johnson KN, Gray RJ, Pockaj BA, Ocal IT, Rose PS, Wasif N. Malignant peripheral nerve sheath tumors (MPNST): the Mayo Clinic experience. Ann Surg Oncol. 2012 Mar;19(3):878-85. doi: 10.1245/s10434-011-1978-7
    This is a review of 175 cases of MPNST over a 15 year period to 2010 treated at the Mayo clinic. 45% were extremity tumours. Local recurrence rate was 22% with 5 and 10 year disease specific survival at 60 and 45%. Tumours greater than 50mm in diameter, local recurrence and high grade were poor prognostic factors.

    Reference

    • orthoracle.com

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