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VET3DPO Box 6476CV6 9LZ
01676 534927 [email protected] www.vet3d.co.uk
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SOP–osteotomyandreductionguidesystem
Deformitycorrection
Pleasereadthesenotescarefullyandcontactusimmediatelyifyourequireanyadditionalinformationorhaveanyconcernsabouttheprintedmodelsorguidessupplied.
Pre-operative
• Unlessspecifiedotherwise,twobonemodelsandtwoguideswillbesupplied.o Pre-operativebone–translucentyellowplastic–forpre-op/intra-oppracticeofosteotomyguidefit–this
canbeautoclaved.o Post-operativebone–whiteplastic–usuallywithfootprintofreductionguidein-situ–forpre-contouringof
plate–autoclavingnotrecommended.o Osteotomyandreductionguides–biocompatibleandautoclavabletranslucentorangeplastic.Recommend
autoclaveprotocolsarebelow,howeverallstandardprotocolsareacceptable.§ 138°Cfor3minutes§ 134°Cfor6minutes§ 121°Cfor15minutes
• FourEllispinswillberequired, and ideally four drill bits of similar or slightly smaller diameter.o ThediametervariesaccordingtopatientsizeandwillbeconfirmedfollowingguidedesignandinthisSOP
whensuppliedwiththemodels.• The3Dbonemodels,andespeciallytheosteotomyandreductionguides,areUVlightsensitiveandshould
bestoredawayfromdirectsunlight(e.g.inadraworbox).ExtendedexposuretoUVlightmayreducethe strengthoftheguides.
Intra-operative
• Astandardsurgicalexposureoftheaffectedboneismade.o Wheneverpossibletheguidesystemwillbedesignedtobeappliedtothemosteasilyaccessibleaspectof the
bonetobecorrected,e.g.lateralhumerus,medialtibiaetc.Positioningoftheguidesystemwillbe discussed withthesurgeonduringtheplanningstage.
• Elevatesofttissuestotheextentrequiredfortheosteotomyguidefootprint.o Supra-periostealexposureisappropriatei.e.asforplateapplication.o Note that adherent soft tissues of any significant thickness will adversely affect guide fit and
should be removed – in juxta-articular locations these might include retinacular and capsularattachments, and in remodelledregionsadherentfibrousmaterial.
• Identifythepositionofosteotomyguidefit.o Thisisusuallyobviousastheguidebecomesstableonceit’sfootprintmatchesthecorticalcontoursbeneath.o Comparisontotheprintedbonehelpsidentifythecorrectposition.
• ApplytheEllispinsthroughtheirchannels(Figure1).o Pre-drillingofthecis-cortexonlywithadrillbitofthesameorslightlysmallerdiameterthantheEllispin
is recommended. Carefully align the drill bit with any one of the channels such that off-axis pressureon the guide channel (which couldmove the guide) is avoided. The transparent, cylindrical natureof thechannels facilitatesalignment.
o Ideallyaftereachcis-cortexisdrilledthedrillbitisleftin-situandanewbitusedforthenexthole.Inthisway thepositionoftheguidecannotchange,howeverwithcarefultechniquethiscanbeachievedwithfewerdrill bits.
o EachdrillbitisremovedsequentiallyandreplacedwithabicorticalEllispin.o If the drill chuck, or later the saw attachment, will contact the end of the previously placed Ellis pin,
that pin can be cut leaving about 1cm emergingfromtheguidechannel.
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• Cuttheconnectingbarsbetweentheosteotomyguideplanes(Figure2).o Cuttheconnectingbarsflushwiththeosteotomyguideplanesurfacesusinganoscillatingsawbladeheld
parallelto,andincontactwith,eachplane.o Althoughtheguidematerialisbiocompatible,amoistswabcanbeplacedbetweenthebarsandtheboneto
catchdebris,andtheareathenlavaged.• Maketheosteotomy/osteotomies(Figure3).
o Ensuretheoscillatingsawbladeremainsparallelto,andincontactwith,eachplane.o OccasionallytheguidemayrideuptheEllispinsduetocontactwiththeblade–aboneclampormanual
pressurewillpreventthis.o It isoftenhelpfultochangetheangleofattackofthebladeoncetheosteotomyhasbeenstarted.This is
sometimesnecessarytoavoidcontactbetweenthesawandthetopoftheguideplane.• Removebothendsoftheosteotomyguide(Figure4).
o TheseshouldslideofftheEllispins.• Placethereductionguide(Figure5).
o ThiswillalignallfourEllispinsinparallel,and,whencontactingthecortexproximallyanddistally,resultsinoptimalre-orientationoftheproximalanddistalbonesegmentsaspre-planned.
o Notethatforclosingwedgeosteotomiestheguidemaybindduetofrictionbetweentheosteotomysurfacesif thesearepoorlyaligned. It isveryhelpful tomanuallyreducethebonesegmentswithall fourEllispinsparallelandtheosteotomysurfacesappropriatelyreducedbeforeslidingthereductionguidedowntheEllispins.
o FulllengthEllispinsarenotnecessary–itiseasiertoslidetheguideifthesehavebeenshortened.Sterilelubricatingjellyappliedtothepinscanalsomakeiteasiertoplacetheguide.
o Contactbetweentheguidebaseandthecortexproximallyanddistallyisnecessaryforplannedalignment–ifrequirednon-pointedreductionforcepscanbeusedtopushtheguideontothebone.
o Pleasenotethereductionguideisdesignedtobeasstrongaspossiblewithinthesizelimitationsimposedbypatientsize,but isnot indestructible.Avoidtheuseofexcessiveforceorapplicationofpoint loading(e.g.pointedreductionforceps)–largeforcesshouldnotbenecessaryiftheaboveguidelinesarefollowed.
• Applytheprecontouredplate(Figure6).o Thiswillbeappliedadjacenttothereductionguide.o CheckthattheEllispinsdonotimpedeplannedscrewpilotholes.Shouldthisoccurpilotholesforcortical
screwscanusuallybeslightlyangled;forlockingscrewsremovaloftheEllispinoncesufficientotherscrewshavebeenplacedisnecessary.
o DonotattempttocompresstheosteotomywiththereductionguideattachedwithallfourEllispinsasthiswillproducestressatthepin/boneinterface.Ifyouwishtocompresstheosteotomytheplateshouldbeappliedsecurelywithatleasttwoscrewseitherproximallyordistally.Ascrewisplacedattheotherendoftheplateinaloadedpositioned,incontactwiththeplatebutnottightened.OnepairofEllispinsisremoved(from either end), and the screw tightened. Obviously undesired relative movement of the osteotomysegmentsispossiblebutunusualunlessplatecontouringisinaccurate.Lightlyappliedbone-holdingforcepsbetween the reduction guide and bone can help maintain alignment but still permit slight compressivemovementofthebones.
• RemovethereductionguideandEllispins.o Asecondplatecanbeappliedinthevacatedspaceifnecessary.
Post-operative
• Weactivelyencouragefeedback–pleaseletusknowyourthoughts.
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Figure1–Theosteotomyguidehasbeenappliedtothe
deformedboneandstabilisedwithfourEllispins
Figure2-Oscillatingsawplaneorientation(paralleltoandincontact
withtheosteotomyguideplane)duringconnectingbarcuttingandthe
osteotomy
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Figure3a–theosteotomieshavebeencompletedparallel
totheguideplanes
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Figure3b–theosteotomieshavebeencompletedparallel
totheguideplanes
Figure4–thetwoendsoftheosteotomyguidehave
beenremoved
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Figure5–thereductionguidehasbeenslidalongtheEllispinsaligningthe
proximalanddistalbonesegmentsasplanned.Reductionismaintainedfor
plateplacement
Figure6–theprecontouredplateisappliedadjacenttothereductiongeode.Theguideandpinsarethen
removed.
