Hersheychapter 16

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Chapter 16: Internal &External,

FixationObjectives of Fixation DevicesRequirements of Implant MaterialsPrinciples Affecting Internal FixationInternal Fixation DevicesAO ObjectivesAO PrinciplesAO Technique

Jumping ScrewsOther TechniquesComplications of Fixation DevicesExternal FixationLarge Bone External Fixation (Ilizarov Technique)Small Bone External Fixation of the Foot


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INTERNAL & EXTERNAL FIXATIONObjectives of Fixation Devices1. Eliminate motion at a fracture or osteotomy site.2. Restore the normal anatomical alignment of the fractured site or thedesired position of an osteotomized segment.3. Assist in the physiological mechanism of bone healing.

4. Permit early mobilization of the area affected by the fracture orosteotomy.

Requirements of Implant Materials1. Materials must be resistant to corrosive environment of the body, yetinert to any foreign body reaction.2. Material must have strength and durability to endure the stress loadsplaced upon it during implantation, bone healing, and subsequent functionof the involved part.3. Material must be available in various sizes and shapes and practical,

enabling fabrication into fixation devices suitable for implantation, withoutthe need for complicated hardware or technique.4. Metals must be compatible with the surrounding environment, thusreducing the pitting and crevice corrosion phenomena which would lead tofatigue fracture of the implant device.5. Use of similar metals within the fixation device to prevent the anode-cathode "battery affect", or the production of hydrogen ions from salinefluid within the body. Acidic environment leads to rapid corrosion andfatigue fracture of implant devices.6. Should be relatively inexpensive.

Principles Affecting Internal Fixation1. Alignment and stability across the fracture site must be developed andmaintained during fracture healing to effect bone healing. 2. TensionBand Principle: Load-bearing through a bone creates one convex andconcave surface subjected to compressive and tension forces.Accordingly, implant devices are applied to the convex surface of boneor to the side of tension, to prevent gapping from tensile forces. Thegapping forces are counteracted with proper positioning and selection ofthe device. This causes counterreactive force of compression across thefracture site, enhancing proper fracture healing.3. Neutralization Principle: Specific anatomic sites are exposed tomultiple stresses, which include torsional and axial loads. These forcesmay change with dynamics of muscle and joint activity. The various loadforces are neutralized at the fracture site with plating in combination withbone screws to minimize movement, especially with multifragmentedfractures.

Internal Fixation Devices


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1. Suture Material:a. Absorbable and non-absorbable sutures are used to re-approximate anosteotomy site. This is done when the osteotomy can be closed withoutany tension. If a non-absorbable material is being used, this fixationdevice is then considered a permanent type.b. The only advantage of this material is that it is very easy to use.

c. The disadvantages are that is provides poor compression and lowtensile strength.

2. Stainless steel wire: 316 LVM surgical steela. Monofilament is better than braided to achieve compression as it istwisted down on itself.b. Its advantages are:i. Its simplicityii. Adequate compression when used properlyiii. Minimal amount of foreign material left in the boneiv. Acceptable in various anatomic locations independent of surface

irregularities and bone cuts.v. Easily retrieved, if necessary, postoperatively, and visable on x-rayc. Its disadvantages are:i. Difficulty in achieving equal compression along the fracture/osteotomysiteii. Possible trauma to bone as the wire is pulled throughiii. Requires good -bone stockiv. Becomes a permanent fixation device.v. Fatigue fracture of wire with motion at the fracture sited. Size used is generally 28 gauge.

e. Tension band wiring using monofilament and K-wires. This techniqueprovides greater stability than that provided by either component usedseparately. The tension band principle applies to bones that areeccentrically loaded. The application of a tension band device on thetension side of a bone allows dynamic compression to be generated onthe opposite cortex.f. MRI may be a problem if wire is present in the foot.

3. Kirschner Wire: 316 LVM surgical steela. Designs:i. Come in different lengths and can also be cut to size

ii. Come as single or double endediii. Come as threaded or smoothiv. Tips are either trochar (slip the least along the cortical bony surfaceand have the greatest holding power), diamond, or cut tip (poorestholding power)b. Sizes include: .028", .035", .045", .062".

c. The advantages are:i. Application to many sites requiring minimal dissection for fracture


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immobilizationii. Can be inserted percutaneously without the need for surgical exposure,specifically for implantationiii. Can be easily removed following surgery once fracture healing isaccomplishediv. Ability to fixate multiple small fragments

v. Can prevent motion on all three body planes, including axial rotation byusing multiple pinsvi. Can immobilize joints by passing wire through a joint surface, thuspreventing undesirable motionvii. Can be incorporated within the cast to protect fixation and maintainpositionviii. Is considered a temporary deviced. Its disadvantages are:i. Creates a track from the external surface of the wound into the boneii. Can be a potential source for introducing bacteriaiii. Requires good patient compliance during the postoperative phase

iv. Threaded wires are difficult to removev. Threaded wires across a fracture site will maintain separation offracture fragments after expected necrosis occurs at fracture.vi. Can break with the bone if exposed to excessive pressurevii. Can migrate or slip out of the bone

4. Stelnmann Pins: 316 LVM surgical steela. Very similar to Kirschner wires except for their size.b. Size ranges from 5/32 to 1 /8 inches in diameter (1.9 mm to 4.7 mm).c. Their rigidity is proportional to the fourth power of their diameter (as

with K-wires).d. Advantages are the same as with K-wires.e. Disadvantages are the same as with K-wires.f. The primary stabilization of subtalar arthrodesis has frequently beenperformed using these pins.g. Are well suited to providing provisional fixation of subtalar and anklearthrodesis as well as calcaneal fractures.

5. Absorbable Pins (Polydioxanone/Polyglycolide): At the presenttime there are two types of pins available. They were originally designedfor fixation of osteochondral fragments, which were previously treated via

excision and abrasion or fixation with K-wires, screws, or adhesives, whichwould leave extensive osteochondral defects.a. Orthosorb (polydioxanone) (Johnson & Johnson):i. This pin is available in only one length (1.3 mm x 40 mm long) and isvery flexible.ii. A tapered variety allows for better compression of osteotomies as theyare inserted into the pilot holeiii. Has been used with success in digital fusions because of its flexibilityiv. Can be cut with a bone cutting forceps


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v. Lose their strength in 4-8 weeks and are totally absorbed in 9-12monthsb. Biofix (self reinforced polyglycolide)(Acuflex):i. Various diameters from 1.5 mm to 4.5 mmii. Various lengths from 10 mm to 70 mm and is very rigidiii. Lose their strength in 4-8 weeks and are totally absorbed in 6

monthsiv. Must be cut with a bone saw or it will shred

6. Staples: Various 2 prong and 4 prong staples are available and aresupplied with templates to assure proper implantation. Available insurgicalsteel and titanium.a. Their application is limited and are best suited for bones with highcancellous/cortical ratios.b. When used primarily in diaphyseal bone there is a propensity for thecortical bone around the staple legs to become communited as the staple

is inserted, resulting in compromised fixation.c. Advantages are:i. Easily removableii. Can be a permanent implantiii. Provides fixation on one plane developing static compression acrossthe fracture fragment site.d. Disadvantages are:i. Should not be used in incomplete fractures independently, unlesssecondary devices or complete non-weight bearing are utilized.ii. Staples can dislodge

iii. Staples can fatigue fracturee. Have been used for calcaneal osteotomies, triple arthrodesis, tib-fibsyndesmosis diathesis, medial and lateral malleolar fractures (withmalleolarscrew), and epiphyseal plate injuries.

7. Osteoclasps: 3/16 LVM stainless steela. Available in five sizes, 8 mm, 10 mm, 12 mm, 14 mm, 16 mm.b. The device requires secondary instrumentation for template positioningof drill holes, and additionally, a tension stat to implant the osteoclaspunder proper tension.

c. Advantages:i. Can be used in various anatomic locations without the need foradditional surgical exposureii. Completely internal and can be considered a permanent implantiii. Creates fixation with dynamic compression across the fracture sited. Disadvantages:i. Limited to incomplete osteotomy where cortical hinge is intact on theopposite side of placement of the osteoclasp deviceii. Technical difficulty with implantation


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iii. Implant may have to be remodeled which weakens its compressionforce and may result in spontaneous loosening

8. Bone Screws: Are used to reappose fracture fragments, their primaryadvantage over any other type of fixation device is that they can providecompression and thus more rigid fixation. Cortical bone screws require

pretapping of drill holes and the thread is finer, whereas cancellous bonescrews can be used for self-tapping locations to create a lag effect across afracture site. Cancellous screw threads are much larger and grasp greatersurface area of bone to achieve fixation.a. Four basic structural dimensions are employed to precisely characterizescrews:i. Root or Core diameter is the minimal diameter of the screw not includingthe threads (Fig. 2).

ii. Thread diameter is the maximal diameter including the screw threads(Fig. 1).iii. Screw pitch is the distance between two successive threads (fig. 3).iv. The lead is the distance a screw advances when turned one completerevolution.b. Other screw parts are:i. Screw head: either cruciform or hexagonii. Screw land: the undersurface of the screw headiii. Screw tip: either round, pointed, or fluted

NOTE* The tensile strength of screws is proportional to the square of theroot/core diameter, and the shear strength of screws is proportional to

the cube of the root/core diameter.


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Al 4.0 mm Partially threaded cancellous screw 1.75 mm pitch

B2 4.0 mm Fully threaded cancellous screw 1.75 mm pitch (Formally 3.5 mmcortical screw

C3 3.5 mm Fully threaded cortical screw 1.25 mm pitch

D4 3.5 mm Fully threaded cancellous screw 1.75 mm pitch

Reprinted from Ruch JA, Vito GR Corey SV (eds); Podiatry Institute Internal Fixation Workbook. 8th ed.,Podiatry Institute Publishing, Tucker, Georgia, 1992, with permission


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iv. Screw shank: the distance between the land and the start of the screwrunout (Fig. 4)v. Screw runnout: the distance from the end of the shank to the first thread( Fig. 5).vi. Screw thread: either assymmetric (buttress) or symmetric (Fig. 6)

c. Cortical Screws: (see figure 7)i. Function as either a positional screw (provide plate fixation) or a lag screw(exerts compression)ii. Compression is only achieved when the threads of the screw do notengage the cortex of the near osteotomy or fracture fragment, accomplishedby overdrilling.

iii. Cortical screws measuring 3.5 mm in diameter are used in lag fashion toprovide interfragmentary compression in the distal fibula, rearfoot, andoccasionally the metatarsals.iv. Screws measuring 2.7 mm, 2.0 mm, and 1.5 mm are also employed tostabilize metatarsal fractures or osteotomies. Screws measuring 1.5 mm areused in the proximal phalanx of the hallux for fracture fixation.

NOTE*

Bone possesses a significantly lower modulus of elasticity than metalalloys. The buttress AO thread is designed to maximize the volume of bonebetween threads and increase the holding potential of the screw in theweaker bone matrix.


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v. When screws are used alone for fragment fixation, two smaller screwsprovide increased resistance to shear and torsional stresses.vi. When screws are used for interfragmentary compression, they should beinserted so that their direction bisects the perpendiculars to the fracture lineand the long axis of the bone involved.

vii. Sufficient screw fixation can usually be obtained with oblique and spiral

fracture patterns only when the fracture line is at least twice as long as thebone's diameter.viii. Short oblique or transverse fractures, therefore need an interfragmentarylag screw and neutralization plate.d. Cancellous Screws: (see figure 7)i. Come either fully or partially threadedii. Cancellous screw thread height is greater than that of cortical. This allowsfor greater purchase in the softer metaphyseal and epiphyseal bone for whichthey were designed.iii. Screw head fixation can be augmented in osteoporotic bone with awasher.

iv. If the threads of a cancellous screw are left in a position crossing theinterface between two fragments, no compression will be achieved, as thelag affect that is desired from this screw will be negated. It then acts as acortical screw.v. Cancellous screws 6.5 mm in diameter are used in ankle and subtalararthrodeses.vi. Lisfranc's injuries are amenable to 4.0 mm cancellous screws.vii. Fractures of the talus and calcaneus are frequently stabilized withcancellous screws (in these locations are generally augmented with washers

Note* If one screw is used for a base wedge osteotomy with an intact corticalhinge, the angle of insertion of the screw should bisect the perpendiculars ofthe long axis of the osteotomy and the long axis of the bone. If the screw isplaced at an angle greater than this, the cortical hinge will disrupt.


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or small plates).e. Washers:i. Generally used in osteoporotic bone.ii. Used with cancellous screw for increasing the purchase power on the nearfracture cortex.iii. Can be used with screws to provide increased surface area as well asbarbs for the reattachment of ligaments or transferred tendon insertions.f. Malleolar Screws:i. Are self-tapping and possess a sharp pointed tip that was designed to allowinsertion without predrilling.ii. Due to their large size, 4.0 cancellous screws have replaced them.g. Cannulated screws:The complications involving placement of screws incomplicated fractures can be greatly minimized with this type of screw.i. This type of screw can be inserted over a guidewire through its entirelength, after the guidewire is properly placed in the bone. This minimizesbony trauma.ii. When a cannulated screw is to be used, the K -wire (guidewire) serves adual purpose of maintaining reduction and providing a guide for screwplacement.h. Herbert Screw:i. Originally designed for osteochondral fractures (also used for scaphoidfractures of the hand), due to the absence of a screw head.ii. Characterized by the presence of threads with different pitches and leadson both its proximal and distal ends. The distal threads feature a tighter pitchand smaller lead and are separated from the proximal ones by an interveningsmooth shank. This allows for interfragmentary compression.i. Reese Arthrodesis Screw: Right/lefthanded threaded screws which areused for digital fusions.

9. Intermedullary Fixation (Nails):These are long pieces of metal ofvarious available diameters which are placed in the medullary canal of afractured/osteotomized long bone to stabilize the site.a. They are:i. Rush pinsii. K-wiresii. Inyo nails (tapered V-shaped stainless device used for fractures of thedistal fibula)

Note* A screw can be used alone for internal fixation whenever the fractureor osteotomy is at least twice as long as the diameter of the bone at thelevel of the fracture or osteotomy.A screw inserted at right angles to the fracture or osteotomy plane gives thebest interfragmental compression, but provides no stability under axialloading. A screw inserted at right angles to the long axis of the bone givesthe best resistance to axial loading, but decreases the interfragmentalcompression. Based on the previous 3 principles, a cortical lag screw isinserted so that it bisects the angle formed by the perpendicular to thefracture plane and the perpendicular to the long axis of the bone


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b. Are wedged into the medullary canal after the canal is reamed to adiameter slightly smaller than the nail to be used, and then removed afterhealing is completed.c. Of all the internal fixation devices used, this one delays bone healing themost by damaging the medullary blood vessels when it is inserted.d. The other major drawback it is limited control of the rotational forces of thefracture fragment.

10. Plate Fixation: Are temporary fixation devices which serve a particularfunction and then are removed. Plates can function in several fashions,depending upon how they are applied and the resulting bone-plate constructgeometry. These functions include rigid fixation through interfragmentarycompression, buttressing, and neutralization.Depending upon the mechanical circumstances, a plate may provide morethan one of these functions.a. The following plates are utilized:i. Static Compression Plates:Tension is applied to the implant and

compression is achieved at the fracture interface.ii. Dynamic Compression Plates: Beyond the compression of thefracture achieved through static compression, the implant is subjected toa physiologic load which generates additional compression at the fractureplaneiii. Neutralization Plates: Initially a shaft fracture may be fixated byinterfragmental compression with a lag screw. A plate is then applied toneutralize or absorb-any disruptive forces; torsional, shear, or bending towhich the bone and osteosynthesis may be subjectediv. Anti-Glide Plates: Are used as neutralization plates but placed on theposterior aspect of the fibula.

v. Buttress Plates: Are used to maintain separation of bone during bonegrafting procedures to gain or maintain length. Are generally used toresist the tendency of metaphyseal fracture fragments to displace whensubjected to compressive forces. Specifically designed plates by the AOgroup are spoon and cloverleaf plates for the distal tibia, and themalleable H or double-H plates for the calcaneus.b. Pre-stressing the plate results in static interfragmentary compression,and is performed by contouring the plate so that its center sits away fromthe bone to which it is applied. The screws securing the plate ends areinserted and tightened first (pre-stressing the plate in tension) so that assequential screws are applied (progressively closer to the center) axialcompression is developed along the underlying bone. In addition,eccentrically plated screws may be inserted (as a compression device) forinterfragmentary compression.c. Plates also function to protect lag screw fixation. Oblique or spiralfracture of the metatarsals or the distal fibula can be stabilized withinterfragmentary lag screws. The addition of a plate then serves toneutralize the bending, torsional, and shear forces that would otherwisejeopardize the fixation obtained by lag screws alone.


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d. The AO group has developed 1 /3 and 1 /4 tubular plates which areeasily contoured.e. The advantages of plates are:i. Allows for complete reduction of fracture fragments and properanatomical alignment.ii. Can be implanted permanently or removed at a later date.

iii. Creates rigid fixation with stabilization and/or dynamic compressionacross the fracture site.f. The disadvantages are:i. Significant amount of surgical dissection for implantation of plate andscrews.ii. High degree of difficulty with irregular or multifragmented bonefractures.iii. Technical difficulty for implantation, potential fatigue fracture of boneplate with motion.iv. Should be applied to the tension side of the fracture to avoidbreaking the bone plate.

iv. Results in a degree of bone necrosis beneath the plate.

11. External Fixator Devices:These devices are available in a variety ofsizes depending upon the location to be used. Their prime indication issevere trauma, especially associated with open fractures. Also can beused in the treatment of infected fractures, non-unions involving theankle, arthrodesis of the subtalar joint or ankle joint, acute and chronicOM, and chronic septic arthritis.

a. Charnley compression clamp: Has been utilized in combination withSteinmann pin fixation. It is applied on each side of the extremity andattached to an exiting pin. Turn-buckle style adjustments are made oneach side of the extremity forcing compression across the fracture site.b. Hoffman fixator devices: Were designed for the small bones of thehands and feet, and have greatly enhanced the use of external fixatortechniques in fracture repair and bone grafting techniques.c. Advantages:i. Ability to be adjusted during the healing phaseii. It is only a temporary device

NOTE* Specific guidelines for their use have been outlined by Kenzora and

Edwards and associates in The Foot and Ankle. They recommended theuse of various configurations of Hoffman's external fixators in order to:a. Stabilize open fracture-dislocationsb. Maintain length where bone is lost or extensively comminutedc. Prevent soft tissue contracturesd. Control joint position for delayed ankle arthrodesise. Provide easy access for bone and soft tissue reconstruction


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iii. Its ability to provide rigid fixation while allowing ready access tosurrounding soft tissues for debridements and dressing changes as necessaryiv. Neighboring joint motion can be preservedd. Disadvantages:i. Difficult to use and requires special instrumentationii. Pin-tract loosening and infectioniii. Requires good patient complianceiv. Creates a bulky external apparatus which will hinder the activity of thepatient

AO Objectives1. Atraumatic operative technique2. Accurate anatomical reduction3. Rigid internal compression fixation 4. Avoidance of soft tissue damage5. The AO tenet: "Life is movement, movement is life".

AO Principles1. Intrinsic Factors Affecting Stable Fracture Reduction:a. Stable fractures:i. Are transverse fracturesb. Unstable fractures:i. Long oblique fracturesii. Comminuted fracturesiii. Spiral fracturesc. Potentially stable fractures:i. Short oblique

2. Extrinsic Factors Affecting Stable Fracture Reduction:

a. The disruptive mechanical forces are bending, shear, and torsion.

3. Mechanical Basis for Stable Fixation:a. Types of interfragmental compressioni. Static compression: a constant and uniform force across afracture/osteotomy site, accomplished by lag screw technique, a preloadedplate, or external fixator.ii. Dynamic compression: is the combination of a statically loaded fixationdevice to a functionally loaded fracture configuration (the tension bandconcept).b. Splintage: A technique applied when interfragmental compression is not

possible and is used in combination with interfragmental compression when italone is not adaquate to provide stable fixation. c. Combinations:combination of techniques of interfragmental compression and splintage (i.e.a single lag screw plus reinforced by a plate).

4. Techniques of Stable Fixation:a. Single lag screw: A cortical screw with a glide hole or a cancellous screwwith all the threads on the distal side of the fracture fragment. A single lagscrew can provide adequate interfragmentary compression, however, is not


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able to withstand shearing and bending loads, so the fracture/osteotomymust be protected.i. Angle of screw insertion: Should be placed so that the angle of the screwbisects the perpendicular of the fracture/osteotomy and the perpendicular ofthe longitudinal axis of the bone. If the angle of the screw deviates from theplane of the fracture, there is a shift of the near fragment in the direction ofthe course of the screw as the screw is tightened and compression iscreated.b. Multiple lag screws (two or more): Are used in a long/oblique or spiralfracture, where the length of the fracture is at least twice the diameter ofthe diaphyseal bone involved.i. Angle of screw insertion: when fixating a fracture/osteotomy withseveral screws, the first screw should be perpendicular to both corticesand be centrally placed. The second and third screws (placed on eitherside of the first screw) are placed perpendicular to the plane of thefracture. This prevents a frontal plane shift, called the shear effect, of thelongitudinal relationship of the fracture fragments. These secondary

screws can also be placed so that they bisect the angle between theperpendicular of the fracture and the perpendicular of the cortical surface.This reinforces interfragmentary compression.

AO Technique1. Instrumentation:i. Thread hole drill bit: (1.1, 1.5, 2.0, 2.5, 3.2 mm)ii. Glide hole drill bit: (1.5, 2.0, 2.5, 2.7, 3.5, 4.5 mm)iii. Countersink: (Mini Fragment Set 1.1 and 2.0 mm tip) (Small FragmentSet 2.0 mm tip) (Large Fragment Set 3.2 and 4.5 mm tip)

iv. Depth gauge: (Mini/Small/Large)v. Tap: (1.5, 2.0, 2.7, 3.5 mm @ 1.25 pitch) (3.5 mm @ 1.75 pitch) (4.5and 6.5 mm)vi. Screw Driver: (Cruciform/Hexagon head)v. Drill and Tap Sleeve: (protection for the soft tissue/ reduces the needfor excessive retraction when the drill bit Is aimed obliquely at thebone/the serrated end anchors well to cortical bone and prevents slippageof the drill bit)


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2. Sequence For Screw Insertion:a. 1.5 mm Cortical Screwi. Pre-drill (0.035 K-wire= 0.9 mm)ii. Thread Hole (1.1 mm)iii. Countersink (Mini)iv. Overdrill near cortex (1.5 mm)v. Depth gauge (Mini)vi. Tap (1.5 mm)vii. Screw Placementb. 2.0 Cortical Screwi. Pre-drill (0.045 K-wire= 1.1 mm)ii. Thread Hole (1.5 mm)iii. Countersink (Mini)iv. Overdrill near cortex (2.0 mm)v. Depth gauge (Mini)vi. Tap (2.0 mm)vii. Screw Placementc. 2.7 Cortical Screwi. Pre-drill (0.062 K-wire= 1.6 mm)ii. Thread Hole (2.0 mm)iii. Countersink (Small)iv. Overdrill (2.7 mm)v. Depth Gauge (Small)vi. Tap (2.7 mm)vii. Screw Placementd. 3.5 Cortical Screwi. Pre-drill (0.062 K-wire= 1.6 mm)ii. Thread Hole (2.5 mm)iii. Countersink (Small)iv. Overdrill (3.5 mm)v. Depth Gauge (Small)vi. Tap (3.5 mm)vii. Screw Placemente. 3.5 mm Cancellous Screwi. As with 3.5 Cortical Screw but eliminate the 2.5 mm Thread Holef. 4.0 Cancellous (partially threaded)i. Pre-drill (0.062 K-wire= 1.6 mm)ii. Thread Hole (2.0 mm)iii. Countersink (Small)

iv. Overdrill (3.5 mm)v. Depth Gaugevi. Tap (3.5 mm)vii. Screw Placementg. 4.0 Fully Threaded Cancellous Screwi. Pre-drill (0.062 K-wire= 1.6 mm)ii. Thread Hole (2.0)iii. Countersink (Small)iv. Depth Gauge


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v. Tap (3.5 mm)vi. Screw Placementh. 4.5 Cortical Screwi. Pre-drill (0.63 K-wire= 1.6 mm)ii. Thread Hole (3.2 mm)iii. Countersink (Large)

iv. Overdrill (4.5 mm)v. Depth Gaugevi. Tap (4.5 mm)vii. Screw Placementi. 6.5 mm Cancellous Screw (partially threaded)i. Pre-drill (5/64 K-wire)ii. Thread Hole (3.2 mm)iii. Countersink (Large)iv. Depth Gaugev. Tap (6.5)vi. Screw Placement

j. 3.5 mm Cortical Screw (using a T-Sleeve)i. 3.5 mm drill (proximal cortex only)ii. 3.5 mm x 2.0 mm drill sleeveiii. 2.0 mm thread hole of the far cortexiv. Countersinkv. Depth Gaugevi. Tap (3.5 mm)vii. Screw Placementk. Exercise: Modified Austin With 2 x 2.7 mm Cortical Screw Placementi. Osteotomy performed with lateral shift of the capitol fragment

ii. Temporary fixation (0.045 K-wire)iii. Temporary fixation: pilot hole for the proximal screw (0.062 K-wire)iv. Pilot hole for the distal screw (0.062 K-wire)v. 2.0 mm thread hole (distal screw)vi. Countersink (distal screw)vii. 2.7 mm over drill (distal screw)viii. Depth gauge (distal screw)ix. 2.7 mm tap (distal screw)x. Insert 2.7 mm distal screwxi. Remove proximal temporary fixationxii. Proximal screw insertion (as just described)

xiii. Remove distal temporary fixationxiv. Tighten screws

3. Plating Procedures:a. Prestressed Plate: Because of the linear design of these plates, thistechnique is best used in long bone fractures. The axial load created by aprestressed plate is a form of static compression, and can beaccomplished three ways:

1. Load Screw Technique:


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and longitudinally placed, and they have two different slopes (the firstacute slope is the compression slope/the second slope is the glidingslope). Both of these features allow for linear motion.

All the screws can be used as load screws (because there is space for thefirst two screws to glide after the other screws are tightened down).

There are individual plates corresponding to the 2.7 mm/3.5 mm/4.5 mmcortical screws.iii. Tension Device:This can be done only with large bones. It is done byanchoring a tension device to one of the fragments and to a free end of aplate, then anchoring the plate to the other side of the fragment and thentightening the tension device. This causes interfragmental compression.

Jumping ScrewsIn case of screw failure you must have a backup or alternative. This explainshow to change screws properly1. To go from a 1.5 to a 2.0 mm screw: Use a 1.5 mm thread hole,followed by a 2.0 overdrill

2. To go from a 2.0 to a 2.7 mm screw: Use a 2.0 thread hole followed bya 2.7 overdrill (may need to re-countersink)

3. To go from a 2.7 to a 3.5 mm cancellous screw: Use a 3.5 overdrill

4. To go from a 2.7 to a 3.5 mm cortical screw: Use a 2.5 thread holefollowed by a 3.5 overdrill

5. To go from a 2.7 to a 4.0 mm cancellous screw (may be the bestchoice): Needs no instrumentation

6. To go from a 3.5 cancellous to a 3.5 mm cortical screw.: Use a 2.5mm thread hole

7. To go from a 3.5 cortical to a 3.5 mm cancellous: Needs noinstrumentation

8. To go from a 4.0 cancellous to a 3.5 mm cortical screw: Use a 2.5thread hole followed by a 3.5 overdrill

Other Techniques1. Splintage: A technique used to splint or protect a reduced fracture. Theprimary uses of splintage are: when interfragmental compression cannot beused, epiphyseal fractures, and to protect a tenuous interfragmentalcompression.

2. Circlage Wiring:The classic application in podiatry is the dorsal loop

NOTE* Never retap after the first screw fails


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technique for an abductory closing wedge osteotomy, even though is hasproven to be the weakest form of internal fixation. It does provide appositionof the osteotomy surfaces, but provides little stability. The most securefixation is two loops in a 90 degree orientation to each other

3. K-wires: A single K-wire rarely provides any rigidity, however, crossed K-wires are best. This is not without its shortcomings as distraction of fracturefragments can occur. K-wire fixation alone does not afford interfragmentalcompression. K-wires do offer stability when used in combination withintraosseous loop techniques. Threaded K-wires are rarely used as they aremechanically unsound.

4. Tension Banding: Monofilament wire threaded in a figure 8 fashion, usedin combination with two K-wires to give interfragmental compression (Figure11). Good with Jones fracture, and some ankle fractures. The plane ofinsertion of the 2 K-wires must be parallel to the plane of the drill hole forpassage of the monofilament wire


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Figure 11: Tension Band Wiring TechniquesReprinted from Ruch JA, Vito GR, corey SV (eds); Podiatry Institute Internal Fixation Workbook. 8th ed.,Podiatry Institute Publishing, Tucker, Georgia, 1992, with permission


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Complications of Fixation Devices1. Infection: Despite long-standing efforts directed at eliminating thiscomplication, there appears to be an irreducible minimal infection ratedestined to plague both patient and physician. The potential exists for thegrowth of resistant bacterial strains or superinfections as a result of

increased use of antibiotics. Studies involving the use of prophylacticantibiotics have shown a decrease in the incidence of postoperativeinfections when fixation devices are used (first-generation cephalosporinsgiven preoperatively provide good coverage against Staph aureus and manygram(-) rods, and are most widely used). Implants frequently need to beremoved in the presence of a deep infection, however, should be left in placein the absence of bony union even with the presence of an infection(infections are difficult to manage without stability, and so do better withstabilization).

2. Slippage of the Fixation Device: Screws, K-wires, as well as the rest of

the fixators can lose purchase and slip out of place. When this happens, thedevice must be removed and replaced with an alternate.

3. Mechanical Failure: Has not been a frequent problem.

4. Inappropriate Use of Fixation Devices:This is a significant problem.Next to infection this is the most common cause of implant failure.

5. Stripping of a Screw Head/ Breakage of a Screw: When strippingoccurs a vise grip is used. When a cancellous screw is removed after manymonths it can break. A cancellous screw is unable to cut bone when it is

backed out, and if excessive torque is applied when bone has grown inaround the smooth shank, the screw can break.

External FixationAn external fixator can be used in many different ways in the fixation of theosseous skeleton. However, the use of an external fixator is presently limitedin foot an ankle surgery. With the understanding of the techniques andtraining now available, should become a more popular method in thesurgeon's armamentarium. The techniques discussed will be divided into

Note* The tension band principle is applied when an eccentric load is placedon a bone, and reduction is attempted. The eccentric load creates aconcavity on one side (which is under tension), and a convexity on theother side which is under compression. The tension band absorbs thetensile force, and the bone (load beam) absorbs the compressive forces.The 2 areas that are easily accessible to this principle in podiatry are the

5th metatarsal and the two malleoli Principles:a. Neutralize the distracting force and convert to a compressive forceb. Apply the tension band to the tension side only (convex side)c. K-wires eliminate the rotational instability


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large bone and small bone fixation

Large Bone Fixation1. Ilizarov technique:This method of external fixation was developed inKurgon, Russia and has been used successfully to treat surgical andtraumatic fractures, osteomyelitis (without sequestrectomy or even

antibiotics), non-unions, osteotomies, fusions, pseudoarthrosis, angulardeformities, limb shortenings, and joint contractures using a surgicaltechnique that respects osteogenic tissues and their vascular supply whilepreserving the weightbearing function of the limb. This is all due to themassive neovascularization coupled with mechanical control of the limbpermitting not only histogenesis of bone, muscles, nerves, and skin, butalso transformation of pathological states such as osteomyelitis, fibrousdysplasia and pseudoarthrosis into normal bone. This technique requiresstrict adherence to certain surgical, anatomic, and mechanical principles.Surgically, it is necessary to maintain the periosteum, endosteum, andbone marrow with its blood supply, via transection of only the bony

cortices.It is important to understand that this technique is very difficult to master,has a long learning curve, and is technically demanding. Because of thecomplexity of the different methods of assembly, no surgical techniquebrochure could possibly explain all of the variations of usage.a. Components:The Ilizarov external fixator is a modular apparatusconsisting of parts that can be assembled in an unlimited number ofconfigurations. With one or more rings affixed to each bone fragment, theframe can be used to compress, distract, angulate, or rotate bone segmentswith respect to each other. In this manner, deformities can be overcomewhile at the same time the limb is made stable enough to permit weight-bearing and functional use.i. Transfixation wires: The mainstay of the Ilizarov system, consisting of 1.5and 1.8mm the latter utilized for lower extremity adult pathology/deformity.

ii. Olive wires: A Kirschner wire with a small bead on it used to abutagainst cortical bone to stabilize or pull bone segments. Can serve several

functions: can act as a stabilizing element, can act as a fulcrum or rotationpoint around which a deformity correction occurs, or can act as a tractionelement to pull bone in a desired directioniii. Rings: Can be either half-rings, full rings, 5/8 circle rings and Omega rings(for the shoulder). The half-rings can be bolted together (sizes from 80-240mm in diameter) and then the wires are secured to them. One ring can bebolted to another ring via threaded rods tightened by a nut on the end.iv. Arches: Arches are large, heavy, curved plates used most commonly forfixation of the upper femur, and come is three diameters, 90, 110, and

NOTE* After a transfixation wire is inserted, one end of the wire is secured tothe frame, the other end of the wire is tensioned before final fixation


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140mmv. Nuts and bolts: Among other things, these secure the half-rings together.The bolts come in 10, 16, and 30mm lengths and the head of the bolt fits a10mm metric wrenchvi. Fixation bolts: Are used to secure wires to the rings and are eithercannulated, grooved, or cannulated with a tapped head. A cannulated bolt isused when a wire passes across the center if a hole at the point of fixation, agrooved bolt is used whenever a wire is tangential to a fixation hole, and acannulated bolt with a tapped head is used when wire fixation is needed in acrowded situation where a connecting rod, socket, plate, or other hardwaremust be attached to the same ring position as a wire.vii. Washers: There are plain washers, grooved washers, and paired sphericwashers. A grooved washer can serve for wire fixation anywhere, and if awire is far off a ring's plane for fixation, enough washers can be stacked on along bolt to secure the wire. A pair of grooved washers surrounded by a pairof nuts on a threaded rod can also secure a wire. A pair of spheric washersare useful in compensating for angulation between a ring and a threaded rodand allow about 7.5 of anglation in a holeviii. Threaded rods: Are the basic connectors between the support rings andcome in lengths from 30 to 400 mmix. Telescopic Tubes: Are used to prevent frame deformity when there is along distance between the support ringsx. Ratchet telescopic rods: Incorporates a ratchet mechanism to simplifydistraction, which the patient can rotate to extend the rod 0.25 mm, and iscalibrated so that the surgeon can assess the elongation or shorteningxi. Posts: Come with one, two, three, or four holes, can have many functions.Two being to act as a fixation point for wires off the plane of a ring, to act asa swivel for ring rotation as well as points for pushing or pulling a ringxii. Buckles: Were Ilizarov's original fixation devicexiii. Plates: Can function as wire attachment points, as a stable supportingelement in push configurations designed simultaneously to angulate and totranslate ring clusters with respect to each other, or to simply enlarge thediameter of, a small ring

Straight plates Paddles Twisted Platesxiv. Sockets: They function not only as interconnectors between threadedrods, but also as spacers to raise a point of attachment off the plane of a ringor plate

xv. Bushings: Due to its configuration, will slide along any rod in a fixationframe. The free movement of such an assembly is used to build amechanism for counterrottation of rings or traction on threaded rods or as aslide assembly to move componants along threaded rodsxvi. Wire tensioners: Are either spring-loaded or threaded. Are used to, applytension to the transfixation wires

b. Ring selection: Allow 2-3 cm of clearance between the inner edges of ringsand the skin


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c. Wire and pin placement: The pins and wires must be placed in certainlocations at specific anatomical levels. The following diagrams show properpin placement at different levels


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d. Wire tensioning: To achieve enough stiffness in the wires to maintainstability and overcome intrinsic tissue resistance, the wires must bestretched like a tightrope. The multiplanar fixation with tensioned wiresprovides an optimal environment for bone formation. The fixation resistsbending and torsion, thus minimizing shear forces at the bone-healinginterface. The use of a Richards dynamometric wire tensioner is preferred toaccurately tension each wire. A calibration scale is noted on this instrumentfrom 50 to 130 kg of force. A tension of 70-110 kg is utilized with a 1.5 mmdiameter wire and 70-130 for a 1.8 mm wiree. Hinge placement: Complex deformities consist of more than one of thefollowing deformities: length, rotation, angulation, and translation. The actualsequence of correction of complex deformities can vary, however, in general,length must be achieved prior to offset and translation, and rotation shouldbe accomplished last. Once the plane of deformity and the maximumangulation and translation have been determined, determination of hingeplacement is necessary. This is worked out by geometry (see Figs 1-5)


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f. Ilizarov corticotomy: The method of limb lengthening or bonelengthening consists of external distraction of a surgically createdosteotomy or corticotomy via a percutaneous, subperiostealincision, perserving periosteum and endosteum. After a latencyperiod after a corticotomy anywhere from 7-14 days, distraction ofthe bone can begin, anywhere from .5 to 1.0 mm per day. This iscalled distraction osteogenesisg. Techniques in fracture reduction: Several factors are taken intoconsideration when a frame is constructed: size and number offracture fragments, plane of the fracture lines, condition of the softtissues, and proximity of the fracture fragment of the joint and

intra-articular involvement. As a general rule one should achieve 2levels of fixation in each major fracture fragment (2 rings applied toany bone segment). The diatance from a fracture line to a ring isusually 3-4 cm, giving enough room for compression or distraction,or angulation and translation. The angle formed by 2 wires crossinga fracture fragment should approach 900 for maximum stability.Intra-articular fractures should be reduced prior to diaphysealfracturesh. Illustration of techniques for the foot and ankle:


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Malleolar fractures

Standard assembly for a transsyndesmotic fibular fracture of theposterolateral rim with medial lesion or in presence of Volkmann fragment:a) Ilizarov technique (Malzev-Kirienko);b) Hybrid Advanced technique with internal osteosynthesis (1 = openreduction, 2 = centralization, 3 = fixation) (Catagni).

Catagni, M.A., Malzev, V., Kirienko, A., Advances In Ilizarov Apparatus Assembly, A. Bianchi Maiocchi (ED),Medicalplastic srl, Milan, 1994


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The universal joint allows movement of the ankle during the postoperativeperiod.

Standard assembly for a malleolar fracture (Malzev-Kirienko).

Lateral view of the assembly for reduction and compression of the medialmalleolus.

Catagni, M.A., Malzev, V., Kirienko, A., Advances In IlIzarov Apparatus Assembly, A. Bianchi MaIocchi(ED), Medicalplastic srl, Milan, 1994


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Distal articular (tibial plafond fractures)

Standard configuration for a typical comminuted fracture of the tibial plafond(Malzev-Kirienko).

Catagni, M.A., Malzev, V., Kirlenko, A., Advances In IlIzarov Apparatus Assembly, A. Bianchi MaIocchi(ED), Medicalplastic srl, Milan, 1994


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CatagnI, M.A., Malzev, V., Kirlenko, A., Advances in Ilizarov Apparatus Assembly, A. Bianchi Maiocchi

(ED), Medicalplastic srl, Milan, 1994


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Equinus foot

Apparatus assembly after correction of the equinus foot;

a) Standard apparatus assembly for correction of an equinus foot deformity.b) Diagram of wire insertion at trascalcaneal and transmetatarsal sites. Afourth wire in the tarsus may be placed according to severity of the case(Malzev-Kirienko).

Catagni, M.A., Malzev, V., KIrienko, A., Advances In IlIzarov Apparatus Assembly, A. Bianchi Maiocchi

(ED), Medicalplastic srl, Milan, 1994


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Small Bone External Fixation of the Foot1. Orthofix modulsystem (Pennig minifixator): Allows for securefragment fixation, with minimum of invasive surgerya. Can be applied under fluorscopy, using minimally invasive threaded rodsb. Allows for 2 pairs of wires to be placed as little as 6 mm apartc. Fracture reduction is possible on all planes

d. Allows for lengthening, treatment of non-unions, soft tissue correction, andany technique for compression or distraction

Indications for use:

Fractures

Aseptic and infected non-unions

Corrective osteotomies

Lengthening

Replantation

PROXIMAL FRACTURES OF THE FIRST METACARPALASEPTIC AND INFECTED NON-UNIONSCORRECTIVE OSTEOTOMIESLENGTHENING

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