Postgraduate Medical Journal (March 1974) 50, 145-149.

Spinal excision osteotomy in myelomeningocele:with special reference to internal fixation

GEOFFREY WALKER PHILIP CHEONG-LEENF.R.C.S. F.R.C.S.

Queen Mary's Hospital for Children, Carshalton, Surrey

THE aetiology and pathology of progressive lumbarkyphosis in children born with myelomeningocelehave been well described by Sharrard and Drennan(1972). In this paper we describe our present tech-nique for correcting this severe deformity, and wediscuss the results obtained in eighteen Spina Bifidachildren between 2 and 11 years of age.

Material and indicationsWe have performed twenty operations in eighteen

children during the last 6 years. The indications wererecurrent skin ulceration in fourteen, and a bizarreand gross deformity in four (Fig. 1). None of the

FIG. 1. Recurrent skin ulceration is a major problemover these angular kyphoses.

children had any useful muscle power in either lowerlimb. Two repeat operations have been performed asthe deformity recurred (vide infra). There werethirteen boys and five girls, and the majority wereaged between 2 and 7 years at the time of surgery.The results of psychological testing were availablein fourteen, and ten were in the 'normal' rangealthough dull (albeit in the lower grades).

OperationUnder general anaesthesia (the assistance of a

skilled and experienced anaesthetist is essential), andwith the child prone an incision is made to allowexposure of the dura and vertebrae. In our experienceit has been safer to re-open the previous verticalincision rather than to convert this to a cruciatewound by routinely using the transverse incisionadvocated by Sharrard and Drennan (1972); as theskin in this area has a poor blood supply and the fourapices of a cruciate scar are prone to necrosis.Decision as to the placement of the incision must,however, always depend on the extent of previoussurgery, and we are fortunate at Queen Mary'sHospital for Children, as primary closure is usuallycompleted with a simple vertical scar, uncomplicatedby flap or transverse incisions. The dura is mobilizedand retained, and this allows exposure of theposterior aspect of the spinal column (Fig. 2).Through small incisions made just along side thelateral masses, a suitable instrument, and then afinger is insinuated anterior to the vertebral body atthe apex of the deformity (Fig. 3). This exposure isextended proximally and distally by blunt dissectionuntil adequate exposure is obtained. With the duraretracted osteotomies are then performed and it isusual to remove one and two half vertebral bodies(Fig. 4). The angles of the osteotomies can best begauged at operation, and are designed to allowmaximum correction with good apposition of thecancellous bone surfaces of the vertebral half bodieswhich remain. Fixation is important, and we nowuse two double wires (SWG 29) passed through theconveniently situated intervertebral foraminae oneither side of the osteotomy (Fig. 5a, and b). In

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146 G. Walker and P. Cheong-Leen

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FIG. 2. The dura is mobilized and retained.

FIG. 3. Through two small lateral incisions, an instrument and then afinger is passed anterior to the vertebral column.

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FIG. 4. Osteotomies are performed to allow removal of one and two half vertebral bodieswith apposition ofthe remaining contiguous surfaces, and as much correction as possible.

addition one or two AO lag screws are used tofurther compress the osteotomy (Fig. 6a, b and c).These may be inserted either proximally or distally,and although their use means that total correctioncannot have been achieved, the firm fixation theyproduce is well worthwhile. The dura will be foundto cover the heads of the screws and the osteotomy,and should be lightly sutured in place, it providesgood subcutaneous tissue between the skin and thespinal column (Fig. 7). The skin is carefully closedwith interrupted sutures over a suction drain. Withthis type of rigid fixation, it has been possible todispense with plaster splintage, and the children arenursed free in bed being turned at regular intervals

for 3 weeks. The amount of blood lost duringoperation has been very variable, but adequatereplacement is essential, and considerable volumesmay have to be transfused.

ResultsOf the eighteen children, two were operated upon

over 6 years ago using a strut of 'Kiel' bone wedgedacross the defect after excision osteotomy. In spite ofimmobilization in plaster for 6 months, both of thesefailed to fuse and each developed a pseudarthrosis.With metallic internal fixation the remainingeighteen, which have all been performed in the last3 years, have rapidly united. However, it is only since

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Surgical correction of myelomeningocele 147

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FIG. 5. (a & b) Double wires are passed through the intervertebral foraminae and tightened.

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FIG. 6. (a & b) AO lag screws are used to further compress the osteotomy site.

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148 G. Walker and P. Cheong-Leen

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FIG. 6 (c) Lateral radiograph showing the position of thewires and screws.

adopting our present technique with two doublewires and one or two AO lag screws producing rigidfixation that we have felt sufficiently confident todiscard plaster splintage. There have been threeoperative deaths (vide infra). Twelve of the remain-ing fifteen children have satisfactory skin cover. Onehas required a pedicle graft; two are awaiting splitskin grafts, in one case for ulceration associated withremoval of a wire which appeared through the skin.The parents' opinion is of interest. Ten of the fifteenwere very grateful and found that removal of theangular kyphosis made management easier (Fig. 8aand b). Five, although grateful, were less pleased aseither there was early recurrence of the deformity orpersistent minor skin ulceration. Two repeat opera-tions have so far been required. One in a child whodeveloped a pseudarthrosis with recurrence ofdeformity 6 years after an abortive Kiel bone graft.In the other, an older boy of 11 years, only moderatecorrection was obtained at the primary operation.This was repeated 16 months later using a transverseincision, and skin necrosis has necessitated a pedicle

flap (Fig. 9). Five of the fifteen children regularlyuse calipers with extensive trunk support, and in onecase the parents specifically mentioned that manage-ment of the urinary appliance was simplified.

Three children collapsed during surgery and in twoattempts at resuscitation were unsuccessful. Thethird survived for 48 hr. The parents of the twochildren who died during operation were 'verygrateful for everything which had been done'. In thethird fatal case, both the original arrival of the child,and her death were accepted fatalistically.

DiscussionThere can be no doubt that kyphosis will inevitably

recur even after sound union of a corrective excisionspinal osteotomy as there are no muscles posteriorto the spinal column. Even so we believe that thismajor procedure is justified, and it is certainlyappreciated by the parents of these severely handi-capped children as management is made a littleeasier. Operation is usually suggested when theproblems, particularly recurrent skin ulceration, anddifficulty with sitting in a wheelchair, defy conserva-tive management. It is essential to discuss thehazards of operation with the parents on severaloccasions, although many will already appreciate therisks involved from discussion with other parents inthe Association for Spina Bifida and Hydrocephalus.On occasions the parents-accepting and appreciat-ing the possible fatal outcome-have suggested thiscorrective surgery.Our first attempts at metallic internal fixation

were with intervertebral wiring, but this necessitatedprolonged plaster fixation. The addition ofShermannbone screws, later superseded by AO lag screws,allows us to discard plaster, and the freedom whichresults is appreciated by the children, nursing staffand physiotherapists. Recurrent skin ulceration hasbeen reduced in extent or eradicated in nearly all thechildren. However, as deformity inexorably re-

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FIG. 7. The dura is replaced and covers the wires and screws.

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Surgical correction of myelomeningocele 149

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FIG. 8. (a & b) Pre- and post-operative photographs toshow the amount of correction which can be obtained

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FIG. 9. A pedicle flap was required in this boy after twoosteotomies, the second with a 'cruciate' scar.

appears, importation of full thickness skin and repeatbone operations will become inevitable in somechildren.

Figure 8b.

While there is no doubt that excision spinalosteotomy can help these severely handicappedchildren and their parents, it is to be hoped that if theteaching of Dr John Lorber (1971) becomes widelyaccepted, it will be these paralysed, incontinent, anddeformed children needing this extensive surgery,who will be 'selected out' during the first weeks ormonths of life.

AcknowledgmentsOur thanks are due to Miss Mary Pugh, Miss P. J. Philpott

and Mr N. Le Page for the illustrations. Mrs Brenda Beal,M.S.C.P., kindly prepared the diagrams, and Miss SusanWadd typed the manuscript.Four of the children were operated on by G.W. in associa-

tion with Mr John Wilkinson and Mr Richard Howard, andwe are grateful for their co-operation.

ReferencesLORBER, J. (1971) Results of treatment of myelomeningocele.An analysis of 524 unselected cases, with special referenceto possible selection for treatment. Developmental MedicalChild Neurology, 13, 279.

SHARRARD, W.J.W. & DRENNAN, J.C. (1972) Osteotomy-excision of the spine for lumbar kyphosis in older childrenwith myelomeningocele. Journal ofBone and Joint Surgery,54B, 50.

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