Injury, Int. J. Care Injured 44 (2013) 327–330
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Technical considerations in microsurgical treatment of paediatric hand injuries Richard D. Lawson *, Michael A. Tonkin Department of Hand and Peripheral Nerve Surgery, Royal North Shore Hospital, The Children’s Hospital at Westmead, Sydney Medical School, University of Sydney, St Leonards NSW 2065, Australia
A R T I C L E I N F O
A B S T R A C T
Keywords: Paediatric Microvascular surgery Replantation Free tissue transfer
Microsurgical techniques are vital for the treatment of many aspects of trauma in the child, both in initial management and later reconstructive surgery. The basic principles of microsurgery pertain to all patients, but there are nuances of technique and of the psycho-social and peri-operative aspects of treatment which are particularly important in the child. It is these distinctions that are examined in this paper. ß 2013 Elsevier Ltd. All rights reserved.
Introduction Microsurgical techniques provide excellent tools for the management of many problems encountered in the management of severe hand injuries in children. Modern microsurgical techniques permit the anastomosis of vessels as small as 0.3 mm in diameter, allowing successful free tissue transfers and replantation in very young children. Successful replantation of a big toe in a three month old patient has been reported.1 Some aspects of tissue transfer are unique to paediatric patients. Free transfer of vascularised physes, for example in toe or vascularised epiphyseal fibula transfers, permits growth to occur in the reconstructed part. The long term effects on growth and function following removal of substantial muscles (e.g. latissimus dorsi) are unknown.2 Whilst the basic principles of microsurgical treatment of paediatric hand injuries are similar to those in adult patients, this article will focus on those aspects of technique particularly relevant to children.
Indications for surgery/Choice of flap In the paediatric patient, every severed part in the upper limb should be replanted if it is safe to do so. Even the most unpromising part can often heal with very useful function and acceptable aesthetic results. Growth in the replanted part may be normal or
* Corresponding author. E-mail addresses:
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[email protected] (R.D. Lawson). 0020–1383/$ – see front matter ß 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.injury.2013.01.011
near normal, particularly in the physes at some distance away from the zone of injury.3 When contemplating microsurgical reconstruction of an injured part, selection of the appropriate tissue to be transferred requires considerable thought. Perforator flaps are gaining in popularity for a number of reasons. Sections of muscle can be incorporated into the flap whilst preserving the majority of the muscle and its function, as in the thoracodorsal artery perforator flap (TAP). Perforating vessels, whilst small, are relatively larger than those of adults when compared with body size, and can be safely anastomosed.4 Innervated flaps, such as the lateral arm flap incorporating the lateral cutaneous nerve of the arm, are more likely to lead to successful return of sensibility in children than in adults. Functioning free muscle transfers usually utilise the gracilis, which is eminently expendable and has a well hidden scar, as well as an attractive muscle fibre length permitting considerable excursion. The rectus femoris and latissimus dorsi are used less commonly; both create larger scars and are more important functionally. Long bone defects are best treated with free fibula transfers. The epiphysis can be transferred when growth is required, for example in traumatic loss of the distal part of the radius. Loss of the thumb is often addressed with transfer of a toe. We consider preoperative angiography, particularly in cases of complex congenital anomaly or extensive trauma, but do not perform it routinely. Adequate peripheral vasculature can usually be established by palpation or Doppler assessment of pulses. In free fibula transplantation an angiogram is not required if both dorsalis pedis and posterior tibial pulses can be palpated.5 We prefer to employ a two team approach, which minimises operative time and operator fatigue. Others prefer that full
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responsibility for preparation of donor and recipient sites rests with one surgeon.6 Preoperative evaluation and psychological aspects The psychological aspects of care for the child on whom free tissue transfer is to be performed are particularly important. The parents must be given the time and attention necessary for them to understand the proposed surgery and to embrace it as the most appropriate option for their child. It can be very helpful to have clinical photographs to show to the parents and child, and it is useful for them to meet families who have already had success with the same procedure. Ideally, trust and understanding will be built up over several consultations. Familiarity with the surgical team and the hospital will engender much greater confidence and will allow the surgery to proceed more successfully for all involved. As the child becomes aware and able to participate to some extent in decisions regarding care the surgeon should gently engage the child and offer the chance to comment on the proposed treatment. With replantation or revascularisation there is little time to build rapport with the patient and parents, but it is comforting for the family to receive a reassurance that every effort will be made to replant any severed part. It is also kind, if one can remember to do so, to have a member of the theatre team provide the parents with progress reports during the usually lengthy surgery.
pressure. We aim to have a urine output of 0.5–1 mL/kg per hour, with blood pressure maintained using intravenous fluids rather than vasopressors, as the latter may result in constriction of peripheral vessels. Regional anaesthesia, augmented by proximally infiltrated long acting local anaesthetic, is employed to minimise postoperative pain. Ideally, an indwelling axillary catheter with a continuous bupivacaine infusion will be placed, which provides excellent analgesia and aids in vasodilation.7 Equipment Access to a high quality operating microscope is fundamental. In addition to the usual microsurgical instruments, a paediatric vessel dilator is a useful item. It is optimal for the instruments used in paediatric cases to be kept separately and used only for those cases1; the tips of vessel dilators in particular are easily damaged with careless use or during sterilisation. Vascular clamps need to be of smaller size and closing pressure than those used in adults. Given the rapid deterioration in the calibration of closing pressure of multi-use metallic clamps, one should consider the use of disposable plastic clamps. 11-0 sutures will be necessary to allow anastomosis particularly of the very small veins sometimes encountered, whilst 10-0 suture is usually appropriate for arterial anastomosis and nerve repair.
Pre-surgical care
Technique
Routine preoperative blood tests should be performed on the patient at the time of surgery and intravenous access should be deferred until the treating anaesthetist is able to place lines. Some paediatric patients pose a considerable challenge to establishing adequate access and it is disheartening for the anaesthetist to have the most promising veins destroyed by unsuccessful attempts at cannulation. In elective cases, the patient should be admitted the day prior to surgery, to minimise anxiety associated with a hasty admission on the day of surgery. He or she should be encouraged to drink fully on the night prior to surgery, the room should be kept warm and all encounters between the medical staff and family should be kept as calm and non-threatening as possible. Sedation should be considered prior to surgery. The aim is to deliver the patient to theatre as warm, calm and well hydrated as possible to minimise the risk of vasospasm.
The small vessel size sometimes encountered in some paediatric microvascular surgery can be daunting; however successful anastomoses can be performed with exacting attention to preparation of the vessels for suture. In fact, there is some evidence accumulating that the vascular pedicle in paediatric patients is relatively larger than in adults.4 Vasospasm is a particular concern in paediatric patients, but one factor in favour of success in this age group is the lack of atherosclerosis.2 Tremor can be minimised with use of supportive bolsters such as sterile gown packs to position the ulnar borders of the hands at the level of the anastomosis. Time should be taken to position the microscope in the optimal position for surgical access and comfort, for both the surgeon and the assistant. The surgeon should be aware of his or her tolerance to caffeine and use this drug appropriately. Use of heavy bone instruments and saws can cause considerable hand fatigue and tremor and should, if possible, be delegated to a member of the surgical team who will not be performing the microsurgical procedure. Whilst we employ interrupted suture techniques in all our anastomoses, in adults and in children, those who usually use some form of continuous suture are advised to avoid this practice in children for the theoretical reason that this may not allow enlargement of the vessel with growth, eventually creating a stenosis. Vasospasm is addressed by ensuring that all aspects of the anaesthetic are optimal, including temperature and blood pressure, and by irrigation of the vessels and anastomoses with verapamil and application of warm moist packs to the area. We do not use lignocaine, as in the concentrations commonly available (1–2%) the drug is a vasoconstrictor. In replantation surgery, fixation is usually successful using fine K wires. Non-union is very uncommon. Every effort should be made to retain length and preserve joints. However, should arthrodesis be necessary, one typically observes a compensatory increase in motion of the adjacent joint in a manner analogous to symphalangism. Physes should also be protected, with passage of K wires minimised and physes avoided if possible.
Anaesthetic considerations Experience in managing anaesthetics for microsurgical cases is vital. The usual difficulties faced in a long case are magnified in paediatric patients because of their high surface area to volume ratio (and consequent difficulties in maintaining body temperature) and lower blood volumes. Temperature management requires maintaining a difference of less than 1 8C between core and peripheral temperature, using warmed intravenous fluids, heating mats and a warm theatre. Suboptimal temperature is a potent cause of vasospasm and also increases blood viscosity. One must however also be aware of the possibility of hyperthermia as the characteristics which compromise maintenance of body temperature in the child may work to increase body temperature to dangerous levels. The importance of balance cannot be overemphasised. An arterial line, central venous access and an indwelling urinary catheter are usual. Blood loss must be closely monitored, with a careful weighing of sponges and close attention to urine output and blood
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In distal and/or very small replantations, on some occasions an adequate vein repair will not be possible. Successful venous outflow can be achieved using several measures. The nail plate can be removed and/or the distal part of the pulp (immediately distal to the nail) can be incised to encourage bleeding, with ongoing bleeding maintained by application of pledgets soaked in heparin. Greater venous outflow can usually be obtained by applying leeches to the part. The child’s haematocrit and haemoglobin must be closely monitored when leeches are used as substantial blood loss may occur and transfusion may become necessary. Indeed, because of the smaller relative size of a flap to the leech in the child, flaps with inadequate venous outflow can also be salvaged with leech therapy, whilst this is inadvisable and rarely successful in the adult. If leeches are used, the treating surgeon must prescribe an antibiotic to cover Aeromonas hydrophilia; we use a third generation cephalosporin such as ceftriaxone for this purpose. Tendon repairs are performed as for adults, although the smaller tendons require finer sutures, usually 4–0 or 5–0 in gauge. We prefer a synthetic braided suture, using horizontal mattress sutures for extensor tendons and a modified Savage (Adelaide)8 repair for flexor tendons when possible; if access is difficult a modified Kessler repair is simpler to perform although not as strong. In these small tendons a simple running epitendinous repair with 6–0 polypropylene is usual. Absorbable skin sutures are humane and time saving; we prefer 5–0 polyglactin (Vicryl RapideTM) in most cases. Dressings/Cast The part replanted or the tissue transferred must be protected but kept visible to inspection. For the forearm or hand this is usually best accomplished using an above elbow cast with a plaster strap incorporated to allow elevation of the part from a drip stand. The fingers are left free within the cylindrical distal part of the cast. The younger patient will be particularly ill equipped to describe any problems relating to excessive tightness of the dressings, and all dressings must be generously padded. Adhesive felt on bony prominences should be considered. Above elbow casts must be applied in at least 90 degrees of flexion to prevent the patient’s arm from slipping out; it is most important when doing this to maintain the elbow at the desired ultimate angle of flexion, as if the elbow is allowed to extend whilst the dressings are applied and is then flexed past 90 degrees unacceptable pressure on the cubital fossa may result. Postoperative monitoring and care We rely on visual monitoring of the replanted or transferred tissue, with observations at 30–60 min intervals for the first postoperative day. Optimally, the patient will be in a microsurgical intensive care or high dependency unit with a single nurse caring for the patient. The patient should be kept fasting for at least the first postoperative day to allow for a safe, speedy return to theatre should this be necessary to salvage a failing part. Sedation using a morphine infusion (10–30 mg/kg/hr)7 followed by nurse initiated intravenous morphine is important to minimise postoperative agitation and pain. Older children may be able to cope with a patient controlled analgesia machine.6 Chlorpromazine at a dose of 50 mg/day is advised by some.1 It is preferable that the same anaesthetist will be involved both pre and post operatively, assisting with pain management and providing a sense of continuity and familiarity. Dressing changes, if necessary, should be done in the operating theatres to minimise patient agitation and movement. Blood soaked dressings must be removed very carefully to avoid damage to the anastomoses by contiguous clot.
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Caffeine in all its forms should be avoided for the first three months after microvascular procedures. Nicotine use is not usually a problem, but parents should be warned about the risks of smoking around their child. Anticoagulation Scientific evidence to guide in the usage of anticoagulation is sparse.9,10 Yildirim uses aspirin for five days and low molecular weight dextran for three days (dose unspecified).1 Parry attributed two early complications in his series of free flaps to excessive bleeding following postoperative use of lowmolecular weight dextran and changed his protocol to using dextran only in cases where there were problems with anastomoses.2 Dextran can be associated with life threatening allergic reactions, and sometimes causes severe headaches. We do not use it. Nikolis’ group presented their experience with intravenous heparin.10 This medication was used in around a third of their patients and was associated with a four fold increase in the rate of complications. A prospective cohort was assessed where intravenous heparin was used only in cases of atherosclerosis, severe crush and/or avulsion, and when intra-operative thrombosis was encountered. With restriction of heparin to this group the rate of complications was significantly reduced whilst maintaining the success rate. Nikolis has therefore continued to use intravenous heparin only in the above patients.10 We echo Kay’s practice in avoiding systemic anticoagulation in uncomplicated replantation or free flap surgery.6 If there is crush/ avulsion injury to the vessels (recognising that a key to anastomotic patency is utilising vessels lying outside the zone of injury) or there is initial anastomotic failure necessitating revision of the repair, we will use intravenous heparin at a bolus dose of 70 mg/kg, with consideration given to continuing the heparin as an infusion postoperatively. We irrigate the vessel lumen with heparin diluted in saline (5000U heparin diluted in 500 mL normal saline) whilst performing the anastomosis. Complications Failure of arterial inflow is signalled by pallor, coolness, loss of turgor and loss of bright red bleeding on pin prick of the affected part. Immediate return to theatre for inspection of the anastomosis is mandatory. Flow may be impaired by swelling, vessel kinking or thrombosis. Revision of the anastomosis is performed as required. Excessive turgor, cyanosis or purple discolouration of the part or flap, or the production of dark venous blood on pin prick of the part are all signs of inadequate venous outflow. The part should be elevated and any tight dressings loosened and tight stitches removed. Failure of speedy resolution (within 15–30 min) is an indication for operative exploration. Ongoing haemorrhage may require control in the operating theatre, particularly if there is any sign that a haematoma is developing as this can quickly compromise the anastomoses. Secondary procedures are common after any microvascular reconstruction or replantation,3 with Lutz et al. reporting a 45% rate in their series of adults and children.11 Differential growth of bones due to damage to physes is particularly important in two bone systems such as the forearm and may require subsequent surgery such as epiphysiodesis or lengthening. Scars may also become tighter with growth and require revision. Capsulotomy, first web space release and tenolysis may be necessary to mobilise joints or tendons. It is wise to broach the possibility of later surgery with the patient and parents once the initial period of recovery is complete, and the part or transfer will definitely survive, as this makes the discussion of secondary surgery much easier should it
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become necessary later in the child’s development. Procedures designed to improve mobility such as tenolysis or staged tendon reconstruction should be deferred until the patient is old enough to comply with physiotherapy, typically between the ages of 6 and 8.
transfer. Whilst the principles of management are the same as those for adults, knowledge of some of the nuances of paediatric microsurgery will improve results and satisfaction for both surgeon and patient.
Results
References
The results of free tissue transfer in children are at least equal to those in adults.2,9 Parry et al. found that surgery was faster, hospital stay was shorter, functional recovery was significantly faster, and there was no vasospasm in their series of 22 patients aged up to 19 with a flap survival rate of 96%.2 Perforator flaps have a similar high success rate.4 Replantation survival rates are lower in paediatric series, averaging around 70%.1,3 This reflects the philosophy of attempted replantation of almost any severed part. Factors affecting survival included the age of the child (older patients faring better), and the level and mechanism of injury, with more proximal digital injuries having better results than distal injuries.3 O’Brien reported an average of 4 mm two point discrimination in the surviving digits.3
1. Yildirim S, Calikapan GT, Akoz T. Reconstructive microsurgery in pediatric population-a series of 25 patients. Microsurgery 2008;28:99–107. 2. Parry SW, Toth BA, Elliott LF. Microvascular free-tissue transfer in children. Plast Reconstr Surg 1988;81:838–40. 3. O’Brien BM, Franklin JD, Morrison WA, MacLeod AM. Replantation and revascularisation surgery in children. Hand 1980;12:12–24. 4. Van Landuyt K, Hamdi M, Blondeel P, Tonnard P, Verpaele A, Monstrey S. Free perforator flaps in children. Plast Reconstr Surg 2005;116:159–69. 5. Lutz BS, Wei FC, Ng SH, Chen IH, Chen SH. Routine donor leg angiography before vascularized free fibula transplantation is not necessary: a prospective study in 120 clinical cases. Plast Reconstr Surg 1999;103:121–7. 6. Devaraj VS, Kay SP, Batchelor AG, Yates A. Microvascular surgery in children. Br J Plast Surg 1991;44:276–80. 7. Wilson RC, Yates APB. Paediatric microvascular surgery: anaesthetic experience of 27 toe to hand transfers. Paediatr Anaesth 1993;3:209–15. 8. Sandow MJ, Kay S. Flexor tendon injuries. In: Prosser R, Conolly WB, editors. Rehabilitation of the hand and upper limb. Edinburgh: Butterworth-Heinemann, Elsevier Health Sciences; 2003; 46–52. 9. Konttila E, Koljonen V, Kauhanen S, Kallio P, Tukiainen E. Microvascular reconstruction in children-a report of 46 cases. J Trauma 2010;68:548–52. 10. Nikolis A, Tahiri Y, St-Supery V, Harris PG, Landes G, Lessard L, et al. Intravenous heparin use in digital replantation and revascularization: the Quebec Provincial Replantation program experience. Microsurgery 2011;31:421–7. 11. Lutz BS, Klauke T, Dietrich FE. Late results after microvascular reconstruction of severe crush and avulsion injuries of the upper extremity. J Reconstr Microsurg 1997;13:423–9.
Conclusion Early concerns about the small diameter of vessels giving rise to technical difficulties in paediatric microsurgery have given way to the understanding that excellent survival rates and functional outcomes can be obtained following replantation and free tissue