SURGICAL TECHNIQUE FOR THE TIBIAL PLATEAU

HYBRID

DFS® HYBRID FIXATOR

Douglas R. Dirschl, MD.Assistant Professor of OrthopedicsUNC School of Medicine

ContentsContents1

Equipment Required...................... Page 3

Components................................... Page 3

Indications.............. ...........................Page 14

Sterilization Recomendations........Page 14

Surgical Technique For Tibial Plateau.............................. Page 4

EBI® DynaFix®Hybrid Fixator

1. Reduction Of The Articular Surface......Page 42. Wire Introduction..................................Page 43. Ring Selection........................................Page 54. Wires To Ring Attachment....................Page 65. Tensioning Wires....................... ............Page 76. Supplemental Fixation............. ..............Page 87. Attachment Of Ring To Fixator .. ..........Page 98. Insertion Of Distal Bone Screws ............Page 109. Fracture Reduction.................... ............Page 12

10. Post Operative Care................... ...........Page 1211. Fixator Triangulation.................. ..........Page 13

The EBI® DynaFix® Hybrid Fixator was designed for the stabilization of

intra and peri-articular fractures where

the fracture pattern and available

bone stock preclude the introduction

of larger diameter bone screws.

The system capitalizes on the

ability to connect ring and small

wire fixation to the flexibility of the

standard DynaFix® for fixation of

metaphyseal humeral, femoral and

tibial applications.

Straight Wire Olive Wire

Variable Bone Screw Carriage(Holding Drop Screw)

Variable WireCarriage

Individual Bone Screw Clamp

Variable Bone Screw Carriage(Holding Triangulating Rod)

Triangulating Rod

ASSEMBLED COMPONENTS

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3

2/3 RingDescription Part#130mm 2/3 ring 13010150mm 2/3 ring 13025180mm 2/3 ring 13040220mm 2/3 ring 13055

1/3 RingDescription Part#130mm 1/3 ring 13005150mm 1/3 ring 13020180mm 1/3 ring 13035220mm 1/3 ring 13050

Straight WireDescription Part#1.6x350 Straight Wire 131501.6x400 Straight Wire 131552.0x350 Straight Wire 131602.0x400 Straight Wire 13165

Olive WireDescription Part#1.6x350 Olive Wire 131201.6x400 Olive Wire 131252.0x350 Olive Wire 131302.0x400 Olive Wire 13135

Ring to Fixator ConnectorPart#13065

Variable Wire CarriagePart#13070

Variable Bone Screw CarriagePart#13080

Triangulating Rod 300mmPart#01520

Individual Bone Screw ClampPart#01525

Wire CuttersPart#13180

Wire PliersPart#13170

Wire TensionerPart#13190

Ring Fixator AssemblyPart#

Left Ring Fixator Assembly 13200Right Ring Fixator Assembly 13210

Assembled Full RingFull Rings may be assembled usingRing Locking Bolts. Ring LockingBolts come prepackaged with all 1/3rings or may be ordered seperately.(P/N 13060)

COMPONENTS

The following are required for the assembly and application of the Dynafix® Hybrid Fixator:

Fixator• 1 DFS® Standard or Small EBI Fixator Complete,

or Left/Right Ring Fixator Assembly• 1 Ring to Fixator Connector (P/N - 13065)• 1 2/3 Ring (Diameters: 130mm, 150mm, 180mm,

220mm, see COMPONENTS)• 1 1/3 Ring assembled to same diameter 2/3 ring if

a Full ring is required• 2 Variable Wire Carriages per wire, minimum 3 wires/6

carriages required (8 on-hand recommended P/N–13070)

• 1 Variable Bone Screw Carriage per drop screw and triangulating rod (3 on-hand recommended P/N–13080)

• 1 or 2 Triangulating Rods (P/N–01520)• 1 or 2 Individual Bone Screw Clamps (P/N–01525)• 3 or more Straight or Olive wires, part numbers listed

under COMPONENTS• Bone Screws (NOTE: Bone Screw diameter should not

exceed 1/3 the diameter of the bone)Tapered Diameters:

6mm/5mm cortical6mm/5mm cancellous 4.5mm/3.5mm cortical 3.5mm/3.2mm cortical

Thread Length of the bone screw should exceed bone diameter by .5 to 1cm to allow 2-3 threads to show beyond the near and far cortices.Overall Screw Length should consider soft tissue, swelling, and access for pin site care after application of the fixator.

Instrumentation• Soft Tissue Guides• Drill Guides and Bits

4.8mm – for 6/5mm Cortical Screws3.2mm – for 6/5mm Cancellous and 4.5/3.5mm

Cortical Screws2.9mm – for 3.5/3.2mm Cortical Screws

• Trocar• 5mm Allen Wrench• T-Wrench for Bone Screws• Mallet/Hammer• Wire Cutters, and wire pliers• Wire Tensioner• Air Drill• Image Intensifier

EQUIPMENT REQUIRED

See the DynafixCatalogue for choice of Bone Screws

4SURGICAL TECHNIQUE FOR TIBIAL PLATEAU

SURGICAL TECHNIQUEFOR TIBIAL PLATEAU

REDUCTION OF ARTICULAR SURFACE

For fractures with intra-articular involvementand displacement, articular fragments shouldbe aligned and bone grafted (if necessary) torestore anatomic alignment of the articular surface. When possible, percutaneous lagscrew fixation is recommended to provideinterfragmentary compression of the articularfragments. As with all fractures, a provisionalreduction of the major fracture componentsshould be carried out prior to wire introduction. The use of a fluoroscope is recommended.

WIRE INTRODUCTION

Wires should be positioned distal to the capsular attachments of the knee joint orroughly 15mm inferior to the joint line. Olivewires should be used in cases where additionalinterfragmentary compression is desired.Appropriate length and diameter wires are chosen based on anatomic considerations andavailable bone stock.

To obtain maximum fixation, a minimum ofthree wires or a combination of two wires anda bone screw should be utilized. The first wireis introduced into the fibular head and guidedto allow for an anteromedial exit through thefar cortex. If introduction through the fibularhead is not desireable, the reference wire canbe introduced just anterior to the fibular head.

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The first wire is introduced through the fibular head and guided to allow for ananteromedial exit through the far cortex.

If the introduction through the fibularhead is not desireable, the first wirecan be introduced just anterior to thefibular head.

Introduction of the first wire using anolive wire.

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Care should be taken to ensure a parallel relationship to the joint line.

Once the wire has passed through the farcortex it should be removed from the drill andtapped with a mallet until an equal amount ofwire is present on the exit side. If olive wiresare used, insertion should continue until theolive engages the near cortex. 9mm and 12mmwashers are available to facilitate small fragment positioning in osteopenic bone.

Once the first wire has been inserted, a variable wire carriage may then be attached to the wire shanks. When loosening the variable wire carriage locking bolt, maintainorientation of the key to allow for free passageof the wire into the carriage. Once in place,the locking bolt should be provisionally tightened to allow for attachment to the ring.

RING SELECTION

The appropriate size ring should allow for at least two finger breadths from the inside ofthe ring to the anteromedial and lateral soft tissue borders. If there are less than two fingerbreadths, the surgeon should opt to utilize thenext largest diameter. The 130mm and 150mmrings may be appropriate for distal tibial,elbow and smaller patients. The 180mm and220mm rings are more appropriately used intibial and femoral fractures in larger patients .Clipping the variable wire carriage into the ring.

Loosening of the variable wire carriagelocking stem. It is recommended that thestem be loosened 3-4 full revolutions toallow for insertion into the ring.

Loosening of the variable wire carriagelocking bolt will allow for free passageof the wire into the carriage. Note that the wire carriage is keyed;proper orientation is essential.

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WIRE TO RING ATTACHMENT

Once the small wire carriage has been provisionally tightened to the wire, it may nowbe attached to the appropriate ring. In caseswhere a full ring is not used, a 2/3 ring should be positioned so that the open portion is oriented posteriorly to allow for range of motion of the knee.

By completely loosening the variable wire carriage ring locking stem, the carriage may be clipped or slid onto the ring. Once the carriage has been attached and the spatial relationship between the wire and the ring hasbeen established, the carriage locking stem isdefinitively tightened using the bone screw T-wrench.

A second wire is then inserted from posteromedial to anterolateral allowing for amaximum convergence between the referencewire. Care should be taken to avoid contact with the reference wire and can be prevented byadjusting the height of the additional wire to beintroduced. The identical technique should beused for wire insertion and if a second olive wireis chosen, the olive should be oriented to engagethe opposite cortex from the first olive wire.

After the second wire has been inserted, a variable wire carriage may then be attached tothe wire. Loosening of the variable wire carriage locking bolt will allow for free passageof the wire into the carriage. Once in place, thelocking bolt should be provisionally tightened toallow for attachment to the ring. The variablewire carriage should then be attached to the ringin the manner previously described.

6SURGICAL TECHNIQUE FOR TIBIAL PLATEAU

The wire carriage can be adjusted tocompensate for various wire angles andheight of the ring.

Tightening of the carriage lockingstem.The variable wire carriage willallow for approximately 3cm of heightas well as accomodate oblique wireplacement.

Posteromedial to anterolateral positioning of the second wire.

The two wires are secured to ring withvariable wire carriages.

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TENSIONING WIRES

Prior to wire tensioning, the wire to variable wire carriage should be examined tomake sure that wires are not prestressed orbent in any fashion. If bowing of the wiresexists, the stem and locking bolt of the variable wire carriages should be loosened and re-positioned to ensure straight wire positioning.

Using the 5mm allen wrench, loosen thewire locking bolt of the variable wire carriage, making sure the opposite variable wire carriagehas been definitively tightened. If using olivewires, the wire locking bolt on the olive side ofthe wire should be definitively tightened.Proper tensioning should commence from theside opposite to the olive.

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An additional wire or bone screw will enhancethe stability of fragment fixation. If a bonescrew is chosen, please refer to the section pertaining to supplemental fixation (page 8). If a third wire is desireable, introduction andattachment to the variable wire carriage andring should follow identical technique for theprevious two wires. The third wire may beinserted distal to the ring. Care should be takento avoid contact between the respective wiresand can be prevented by adjusting the height ofthe additional wires to be introduced.

Definitive locking of variable wire carriage using 5mm allen wrench and T-wrench for bone screws. This shouldbe done on the side opposite of the tensioner prior to tensioning wire.

Loosening of variable wire carriagelocking bolt prior to tensioning.

Addition of a drop wire, enhancing stability.

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SUPPLEMENTAL FIXATION

Bone screws may be attached to the ring construct. By loosening the bone screwcarriage locking stem, it may be clipped intothe circumference of the ring as desired.

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Attach tensioner to the wire. The wire carriage locking bolt on the side to be tensioned should be loosened prior to definitivetensioning. The tensioner should then belocked onto the wire by securing the tensionerbolt with a 5mm wrench.

Wire tension should range from 70kg to 100kg for a 2/3 ring, and 100kg to 130kg for afull ring depending on the quality of the bone.Once adequate tension has been achieved,definitively lock the wire carriage locking boltwith a 5mm allen wrench prior to removing thetensioning device. Wires should be clipped andbent after tensioning.

NOTE: The tensioner bolt position must bereset after tensioning as shown in pictureabove left. Tension the remaining wires as previously described.

SURGICAL TECHNIQUE FOR TIBIAL PLATEAU

Tightening of tensioner bolt prior totensioning the wire.

Addition of variable bone screw carriage for placement of supplementalscrew.

Wire clipping.

Once adequate tension hasbeen achieved,definitively lock the wire carriage lockingbolt with a 5mm wrench prior to removing the tensioning device.

Tensioner boltWire Carriage Locking Bolt

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ATTACHMENT OF RING TO FIXATOR

A ring to fixator connector is then attached to a standard DynaFix® fixator. Removal of atelescoping component is necessary to completethe frame. For left proximal tibias, the left telescoping arm is removed and replaced by aring to fixator connector. For right proximaltibias, the right telescoping arm is replaced by a ring to fixator connector. Once this has beenachieved, the two locking bolts of the ring tofixator connector are inserted through the ringand tightened into the fixator construct andplaced in an anteromedial fashion.

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To facilitate attachment to the variablebone screw carriage, sufficient bone screwshank is necessary. A minimum bone screwlength of 150mm is recommended.

Insert bone screw through variablebone screw carriage.

The shank of the additional bone screwis then attached to the variable bonescrew carriage and locked.

Securing fixator to a ring-to-fixator connector.

Predrilling for supplemental bone screwthrough drill guide.

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INSERTION OF DISTAL BONE SCREWS

With the locking connector bolts loose, the fixator is positioned to allow for anteromedialinsertion of the distal bone screws. Forenhanced stability, the bone screws should beintroduced in positions one and five of thebone screw clamp. Prior to bone screw inser-tion, the telescopic arm of the fixator should beopened approximately 1cm to allow for subse-quent compression.

Using the 5mm allen wrench, the clampcover screws should be loosened to allow ade-quate room for the necessary soft tissue anddrill guides. A 1cm incision is made and bluntdissection is continued to the bone. The trocarand appropriate length soft tissue guide arethen inserted into the bone screw clamp andutilized to identify the center of the bone andto establish the orientation of the screw tract tobe pre-drilled. It is desireable to place the bonescrews perpendicular to the mechanical axis ofthe bone.

Once the screw site is selected, use gentlepressure to maintain contact between the softtissue guide and the cortex of the bone.Extract the trocar. The soft tissue guide istapped with a mallet to engage the soft tissueguide with the bone. Insert the appropriatedrill guide into the soft tissue guide. (See DrillGuide / Drill Bit Sizes.) Bone screw diametershould not exceed 1/3 the diameter of bone.

Insert the matching drill bit with drill stopinto the drill guide.

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SURGICAL TECHNIQUE FOR TIBIAL PLATEAU

Drill Bit/Drill Guide Sizes Tapered Bone Screw Diameters

4.8 mm 6/5 mm Cortical

3.2 mm 6/5 mm Cancellous

3.2 mm 4.5/3.5 mm Cortical

2.9 mm 3.5/3.2 mm Cortical

(Bone screw diameter should not exceed 1/3 diameter of bone.)

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After bi-cortical penetration of the drill, thedrill bit and drill guide are withdrawn.

(A drill stop may be used to prevent overpenetration of the drill bit into underlying softtissue structures.)

Maintain gentle pressure on the soft tissueguide so as not to lose the position of the pre-drilled hole.

The appropriate length bone screw is insert-ed through the soft tissue guide. The bonescrew T-wrench is used to advance the screwinto bone. To obtain optimal purchase, allbone screws must be bi-cortical with no lessthan 2mm protruding from the far cortex andabout 5mm remaining outside the near cortex.Image intensification is utilized to confirmdepth of penetration.

Care must be taken to avoid over penetration. Due to the tapered design, bone screws must not be backed out or theywill lose purchase.

A second bone screw is introduced in identi-cal fashion to the previously described tech-nique making sure the clamp cover lockingbolts are tightened over the soft tissue guides.This will prevent prestressing of the bonescrews.

Once all bone screws have been inserted,remove the soft tissue guides and tighten theclamp cover locking bolts providing at least3cm of clearance between fixator body andskin surface.

Inserting appropriate soft tissue guide,drill guide and bit for drilling of bicortical bone screws.

Distal bone screws inserted.

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FRACTURE REDUCTION

Final reduction below the ring may beaddressed systematically. Length is accomplished by the distraction (manually or incrementally) of the telescoping fixatorarms. Compression or distraction can beaccomplished by loosening the telescoping set screw closest to the central portion of thefixator.

When the desired position has been achieved,all fixator fittings must be tightened with a5mm allen wrench.

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SURGICAL TECHNIQUE FOR TIBIAL PLATEAU

Rotation about the axis of the fixator can be achieved by releasing the rotational set screw in the silver component of the central body. Forangular or translational adjustments, acorresponding adjustment in length isrequired. This is achieved by looseningthe telescoping set screw closest to thecentral portion of the fixator.

Anterior/posterior translation may beachieved by simultaneously loosening thelocking connector bolts that are in thesame plane as the bone screws.Medial/lateral translation may be achievedby simultaneously loosening both proximal and distal locking connectorbolts in the same plane as the clamp coverscrews.

Varus/Valgus angulation can be correctedby loosening the most proximal or distallocking connector bolts that are in thesame plane as the clamp cover screws.Recurvatum/Procurvatum may be corrected by loosening the most proximalor distal locking connector bolts that arein the same plane as the bone screws.

The following two diagrams illustrate the fixator’s reduction capabilities. For example, if placed in the medial plane,the following corrections are possible:

Telescoping Set Screw Rotational Set Screw

POSTOPERATIVE CARE

At the conclusion of fixator application and fracture reduction, wounds are dressed inroutine sterile fashion. Care should be taken toinsure all fixator fittings are securely tightened.Dry sterile gauze is wrapped around the wiresand shanks of the bone screws to prevent pistoning of the soft tissues on the bone screws.Once wounds have healed and sutures areremoved, routine postoperative screw site careis recommended. (Refer to EBI “Pin Site Care Instructions” brochure, P/N 192143)Screw sites should be monitored during subsequent clinic visits. All fixator fittingsshould be evaluated for tightness during subsequent clinic visits.

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FIXATOR TRIANGULATION

Triangulation of the ring construct is recommended to provide increased stabilitybetween proximal and distal points of fixation.

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A variable bone screw carriage isattached to the posteromedial or posterolateral aspect of the ring.

A triangulating rod is then slid throughthe variable bone screw carriage andtriangulated to the distal bone screwclamp.

Lock with a 5mm allen wrench.

Attach an individual bone screw clampto the distal end of the triangulatingrod and to the bone screw shank.

INDICATIONS

The EBI® DynaFix® Hybrid System is indicated for the stabilization of intra and peri-articular fractures where the fracture pattern and available bone stock preclude theintroduction of larger diameter bone screws.The EBI X FIX® DynaFix® System is a unilateral external fixation device intended foruse in the treatment of bone conditions including leg lengthening, osteotomies, arthrodesis, fracture fixation, and other boneconditions amenable to treatment by use of the external fixation modality. This device isintended for fracture fixation and should not beused for limb lengthening.

Caution: Federal Law (U.S.A.) restricts thisdevice to sale by or on the order of a physician.

Warning: This device is not approved forscrew attachment or fixation to the posterior elements (pedicles) of the cervical, thoracic orlumbar spine.

EBI, as the manufacturer of this device, doesnot practice medicine and does not recommendthis or any other surgical technique for use on aspecific patient. The surgeon who performs anyimplant procedure is responsible for determiningand utilizing the appropriate techniques forimplanting the device in each individual patient.EBI is not responsible for selection of the appro-priate technique to be utilized for an individualpatient.

STERILIZATION RECOMMENDATIONS:The fixator should be completely dismantled for cleaning, but it may besterilized in the assembled state, providing all screws and couplers are leftloosened.

The DFS® components and instrumentation are provided non-ster-ile, and must be sterilized prior to use. All packaging materials must beremoved prior to sterilization. All fixator components should be sterilizedin a loosened state such that the connected components move freely.

The following steam sterilization parameters are recommended:Cycle: VacuumTemperature: 2700

Time: 4 minutesNote: Allow for cooling

Individuals or hospitals not using the recommended method, temperatureand time are advised to validate any alternative methods or cycles using anapproved method or standard.

14SURGICAL TECHNIQUE FOR TIBIAL PLATEAU

PN: 192223 7/98

HYBRID

EBI Medical Systems, Inc. • 6 Upper Pond Road, Parsippany, NJ 07054 • http://www.ebimedical.com • 1-800-526-2579