Practical Guide to Linear External

In Practice ● FE B R U A R Y 2005476

EQUIPMENT

BASIC COMPONENTSThe original external skeletal fixation system is theKirschner-Ehmer system (Veterinary Instrumentation).Subsequent improvements, primarily in clamp design,have been incorporated into the second generationSecuros (Orthomed) and IMEX-SK (Animalcare) sys-tems. Many components are interchangeable between thesystems, and the principles of application of a ‘generic’fixator are the same, irrespective of which system is used.The exception is the acrylic pin external fixation (APEF)

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EXTERNAL skeletal fixation is a very adaptable technique that can be used to stabilise a wide variety of fractures. A basic frame can be applied using relatively inexpensive equipment, and confidence in the procedure can be quickly gained by starting with ‘simple’ fractures and applying straightforwardprinciples. As familiarity with the technique increases, frames can be used to manage more complexfractures and angular limb deformities, or for temporary transarticular fixation to protect ligamentrepairs or manage severe soft tissue shearing injuries. This article discusses a step-by-step approach to external skeletal fixation and unravels some of the associated terminology.

Practical guide to linear external

skeletal fixation in small animals

SANDRA CORR

External skeletal fixation canbe used to manage a widerange of simple and complexfractures

system (Veterinary Instrumentation), where the pins areset into an acrylic column rather than clamped to a metalor carbon bar (see box on pages xxx and xxx).

FRAME SIZEAs a broad guideline for the original Kirschner-Ehmersystem, it is recommended that the ‘small’ system beused for animals weighing ≤5 kg, the ‘medium’ systemfor animals weighing between 5 and 30 kg, and the‘large’ system for animals weighing >30 kg. While theseare useful guidelines, the basic rule to follow is that pinsize should be chosen first, and this should not exceed 25to 30 per cent of the bone diameter. This will subsequent-ly determine the choice of clamps and connecting bars,taking into account factors such as the fracture configura-tion, expected healing time, and the level of activity thatan animal undertakes. A list of component sizes for thedifferent systems is given in the table on the facing page.

FRAME SHAPEA frame consists of multiple pin-clamp units, and the fun-damental principle is that every pin must pass through twocortices to function. A ‘half pin’ passes through one skinsurface only to attach to a bar on one side, while a full pinpasses through both skin surfaces, connecting to a bar onboth sides. The terminology used to describe the resulting‘constructs’ is based on whether there is a connecting baron one or both sides of a limb, and whether the bars are insingle or multiple planes. In general, type Ia frames areweaker than type Ib frames, which are weaker than type IIframes, which are weaker than type III frames (see illustra-tions on pages xxx and xxx). Truly bilateral frames cannotbe used above the elbow or stifle due to the presence of the

Sandra Corrgraduated fromGlasgow in 1985, and spent six years in small animal andequine practice. Shesubsequently workedat the University ofZimbabwe as alecturer in smallanimal surgery fortwo years, beforereturning to the UKto undertake a PhD in xxx? at the RoslinInstitute and aresidency inorthopaedics atGlasgow. She iscurrently a lecturer in small animalsurgery at the RoyalVeterinary College. The basic frame

A basic external skeletal fixation frame is createdfrom pins driven percutaneously into the bone, andattached to one or more connecting bars placedoutside the body. This type of fixation has the following distinct advantages:■ As the implants bridge the fracture site external-ly, rather than internally, closed fracture reduction is often possible, thereby better preserving the biological environment of the fragments and sur-rounding tissues;■ The external frame can be adjusted to improvefragment reduction and alignment based on post-operative radiographs;■ The stiffness of the frame can be reduced ashealing progresses, to increase loading on the fracture.In Practice (2005)

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In Practice ● FE B R U A R Y 2005 477

Increasing the strength of an external skeletal fixator-bone construct

■ Increase load sharing with the bone by minimising the fracture gap ■ Increase the component size. This essentially relates to pin size, which shouldnot exceed 25 to 30 per cent of the bone diameter. Pin stiffness is proportionalto pin diameter4

■ Increase the number of pins (three to four pins in the most proximal and dis-tal fragments)■ Use full pins instead of half pins■ Minimise the bone to clamp distance. Pin stiffness is inversely proportional topin length3. A shorter pin-clamp distance also aligns the frame closer to the bio-mechanically stronger central axis of the bone. However, it should be possible toinsert a finger between the skin and the clamp to prevent postoperative swellingfrom causing pressure necrosis of the skin■ Add extra connecting bars

External skeletal fixation pins are made of hardenedstainless steel, and are stiffer and more resistant to bending than Steinmann pins. (A) Negatively threadedEllis pin. The threads are cut into the shank, making the pin relatively weak. The weakest point is the thread-shaft junction (arrow), which must be protectedwithin the medullary cavity. (B) Smooth pin (trochar point). (C) Positive-profile pin. The thread diameter isgreater than the shank diameter, making this type of pinstronger than Ellis pins. (D) Centrally threaded positive-profile pin. (E) End-threaded positive-profile pin

(A) (A)(B)

(B)

(C)

(C)

(D) (E)

(left) External skeletal fixation clamps. (A) Standard Kirschner-Ehmer clamp, (B) Securos clamp, (C) IMEX-SK clamp.Loosening the nuts enables Securos and IMEX-SK clamps to be attached to a connecting bar at any stage of frameconstruction; this is not possible with the standard Kirschner-Ehmer clamp. (above) IMEX-SK clamp attached to aradiolucent carbon fibre connecting bar

Clamp size Pin shank diameter Connecting bar diameter

Kirschner-Ehmer Small 2·0-2·4 mm 3·2 mmMedium 3·0-3·2 mm 4·8 mmLarge 4·0 mm 8·0 mm

Securos Small 1·6-2·4 mm 3·2 mm Medium 2·4-3·2 mm 4·8 mmLarge 3·2 mm 9·5 mm (CF)

IMEX-SK Miniature? 0·9-2·4 mm 3·2 mm Small 2·4-4·0 mm 6·3 mm (CF+T)Large 2·8-4·8 mm 9·5 mm (CF+A)

Connecting bars come in a range of lengths and are made of stainless steel, except where indicated. CF Carbon fibre, T Titanium, A Aluminium

EXTERNAL SKELETAL FIXATION SYSTEM SIZES

body wall, although a type I frame is too weak to resist theforces produced by the combination of limb loading andthe large muscle masses in these regions. The basic type Iframe can be strengthened for such applications by ‘tying-in’ an intramedullary pin. Another modification of the typeI frame is the transarticular fixator (see page xxx).

FRAME STRENGTHAs with any implant, the type of frame that is chosenmust be strong enough to resist the forces acting on thefracture, as determined by the fracture configuration andthe bodyweight of the animal (see box on the right).

APPLICATION OF A BASIC ‘GENERIC’ FRAME

Routine preoperative investigation and stabilisation of a traumatised animal should be performed prior to gener-al anaesthesia and fracture repair. Analgesia should beprovided and the limb externally coapted, where appro-priate, to improve comfort and minimise swelling. It isdifficult to adequately support fractures of the femur orhumerus with external coaptation, and these are betterleft unsupported.

STAGE 1. FRACTURE PLANNINGFracture configuration should be assessed using wellpositioned and correctly exposed orthogonal radiographicviews of the limb. Care must be taken to identify any fis-sures that could split on pin insertion. A ‘fracture plan’should be made by tracing the fragments and then ‘recon-structing’ the bone, enabling a scaled plan of the repair tobe drawn (see page xxx). This avoids much of the guess-work in deciding where to place the pins, especially fol-lowing a closed reduction. It is also advisable to have a‘plan B’ (ie, an alternative frame or fixation method)!

STAGE 2. PREPARATIONThe patient should be prepared for surgery as normal.Positioning the animal using the ‘hanging limb’ tech-nique is recommended (see page xxx), as this helps torealign the fracture, and stretch and fatigue the muscles.

Towel forceps should be clipped onto a toenail orthrough a sterile bandage wrapped around the foot,instead of onto the interdigital skin which can tear easily.The limb is suspended just above the table until surgerybegins, at which point the table can be raised slightly tosupport the animal’s weight.

STAGE 3. APPLYING THE FIXATORPins must be placed through ‘safe corridors’, asdescribed by Marti and Miller (1994a,b), to avoid majorneurovascular tracts, muscle masses and tendons.Careful palpation of the bone helps to identify theseareas. Care should be taken to avoid placing pins intogrowth plates in immature animals. Inadvertent jointpenetration can be avoided by placing hypodermic nee-dles into the joint spaces to act as markers.


(above and below) Type Ia external skeletal fixator. This unilateral, uniplanar frame is the weakest configuration,and is only suitable for simple fractures in small dogs and cats

(above and below) Type Ib external skeletal fixator. Thisunilateral, biplanar frame configuration is composed of two unilateral type Ia frames, usually positioned at 90°to each other. It is a relatively weak construct and is usedfor simple fractures in small dogs and cats; however, it canbe made stronger by linking the frames proximally anddistally

A sharp skin incision should be made with a number11 scalpel blade, and the soft tissues separated down tothe bone by blunt dissection using mosquito forceps.Failure to create a large enough portal results in the softtissues binding up around the drill bit or pin. Ideally, softtissues should be protected using drill guides or smallGelpi retractors.

Applying the pins■ Place the most proximal and distal pins first, prefer-ably parallel to the adjacent joint surfaces.

■ Attach the connecting bar(s). If standard Kirschner-Ehmer clamps are being used, the bar(s) must be preloaded with the appropriate number of clamps, asdetermined in the fracture plan. With the Securos orIMEX-SK kits, or if Kirschner-Ehmer split clamps arebeing employed, clamps can be added to the bar(s) atany stage.■ Insert the remaining pins through the clamps. Ideally,a minimum of six cortices should be engaged in the mainproximal and distal fragments.■ Threaded pins should be inserted parallel to each


(above and below) Type III external skeletal fixator. Thisbilateral, biplanar frame is the strongest configuration. It is composed of a type Ia frame linked to a bilateral frame(usually placed at 90° to each other). This type of fixator ismost useful for severely comminuted fractures of the tibia.Pins can be linked to connecting bars using single or doubleclamps

(above and below) Type II external skeletal fixator. Thisbilateral, uniplanar frame is stronger than those pictured on the previous page and is used for more complexfractures. The presence of the body wall limits its use tobelow the elbow and stifle. The frame has at least one fullpin per proximal and distal segment, with two connectingcolumns that span the fracture and connect the fixationpins. The number of full pins can be varied to create framesof differing strengths, making this the most commonlyapplied configuration

other, and perpendicular to the bone. This is easiest,most biomechanically sound, and makes the best use ofthe bone stock.■ Non-threaded pins should be placed at 70° to thebone to increase pull-out resistance. ■ Pins should be no closer than three times their diame-ter to a fracture line or joint surface.■ If bone stock is limited, it may be necessary to bridgea joint (eg, the distal tibia and the tarsus-proximal meta-tarsus) or to use an adjacent bone (eg, the proximal ulnaif the proximal radius is fractured).

The pin-bone interfaceAssuming that the clamps remain tight, the security of theframe depends primarily on the pin-bone interface. Thiscan fail either due to thermal necrosis created during pininsertion, or as a result of excessive local stresses on thepin, or a combination of both. These problems can be min-imised by following the rules listed in the box on page xxx.

STAGE 4. POSTOPERATIVE RADIOGRAPHYOrthogonal views should be taken to assess:■ FRACTURE ALIGNMENT AND REDUCTION. If this is sub-


optimal, some adjustment is possible by loosening theclamps and manipulating the pins; ■ PIN POSITION. Pins that are not correctly seated in thetrans-cortex can be adjusted aseptically in the radiogra-phy room by loosening the clamp and advancing orretracting the pins using the drill. Pins that are too closeto fracture or fissure lines, or joint surfaces, should beremoved and replaced in theatre.

STAGE 5. IMMEDIATE POSTOPERATIVE CAREBandaging should be applied in two layers:■ An inner layer should be placed between the frameand the skin to reduce skin movement and swelling, andabsorb discharge. Sponges from disposable surgicalbrushes are ideal; these can be dried and resterilised.This layer is maintained until the pin tracts have stoppeddischarging (four to five days).

Modifications of the basic frame. (A) ‘Tied-in’ frame. The intramedullary pin is placed first to align the fragments, and thenbent over and linked to a type I frame (either directly or using a separate connecting bar), considerably increasing the framestrength. This type of configuration is most commonly used for fractures of the humerus and femur, but is also applicable to the tibia. (B) Transarticular frame, which has been applied to temporarily immobilise the elbow following reduction of a luxation of the radial head. (C) Transarticular ‘A’ frame. An extra bar attaches the proximal and distal ends of a transarticular frame to resist large bending forces. When using transarticular and ‘A’ frames, the joint must be set at a functional angle to allow limb use, and the frame should ideally be removed within three weeks

Fracture planning. (A) Radiograph showing acomminuted fracture of thedistal tibia and fibula in a cat.(B) Tracing of the fracturedbone, outlining the majorfragments, which have been measured. The distalfragment was too small tohold three external skeletalfixation pins, so the decisionwas made to ‘reconstruct’ thebone using lag and positionalscrews, and protect the repairwith a transarticular frame. (C) Plan showingreconstruction of the boneand the position of thescrews. (D) Postoperativeradiograph of the fracturereconstruction; this can beuseful to check the positionof the screws and the externalskeletal fixation pins beforethe connecting bars areattached

(A)

(A) (B) (C) (D)

(B) (C)


■ A second (outer) layer covers the frame at all times todecrease the likelihood of the frame catching and beingpulled off, and to protect the owner’s legs and furniture!The distal limb should also be bandaged for the first 24to 48 hours to reduce postoperative swelling. Thereafter,the distal limb should be left undressed to encourage theanimal to use the leg, and any swelling should berelieved by gentle massage.

Owners should be advised to monitor the pin sites;some redness and swelling is to be expected in the firstweek, along with mild serosanguineous discharge.Excessive or prolonged discharge, especially if dis-coloured, indicates pin tract infection or pin loosening,both of which are associated with increased lameness.Owners should be asked to restrict dogs to short, leadwalks while the fixator is in place.

STAGE 6. FOLLOW-UP ASSESSMENTRadiographs should be taken three to four weeks postop-eratively in immature animals, and six weeks in adults –or sooner if there is concern about progress. Clinicalunion often occurs before radiographic union is evident,so clamps can be loosened and the fracture site manipu-lated to determine if the fracture is stable.

Bone healingA major advantage of using external skeletal fixation isthat surgical invasion of the fracture site is not requiredto obtain anatomic reduction and alignment. The soft tis-sues and vascular supply to the fragments are therebypreserved. As a fracture gap usually remains, interfrag-mentary compression is rarely achieved and, therefore,secondary (indirect) bone healing results. The strongerand more stable the frame, the less callus formation isseen radiographically. While a certain amount of axialmicromotion creates beneficial strains across the fracturegap, excessive axial motion or bending, twisting andshearing forces are detrimental to fracture healing. Thus: ■ An overly weak frame will result in excessive callusformation and potential premature pin loosening andfailure;■ An overly strong frame can result in excessive ‘stressprotection’, where the beneficial microstrains are absent,

leading to delayed or non-union with a generalised lossof bone mineral density. This can be addressed by stageddisassembly of the frame, with or without bone grafting.

Staged disassemblyStaged disassembly (or ‘destabilisation’) is controlledreduction in the stiffness of the frame to increase loadingof the bone. This can be carried out by: ■ Removing individual pins; or■ Converting a type II frame to a type I frame byremoving the connecting bar (and trimming the pins) onone side.

The most proximal or distal pin should not beremoved, as leaving empty pin tracts in positions notspanned by the frame can produce ‘stress risers’ (focalconcentrations of stress), thus predisposing the bone tofracture through the empty holes.

Studies on the effects of destabilisation have pro-duced variable results. It would appear, however, only tohave a positive effect on fracture healing when per-formed between six and 12 weeks after fracture repair(Egger and Histand 1993).

Hanging limb technique. Theleg remains suspended afterbeing prepared and draped

Insertion of proximal and distal pins,with hypodermic needles markingthe tibial border of the stifle joint

Preserving the bone-pin interface

The heat generated during drilling can be min-imised by using a low speed, high torque drill toinsert smooth and Ellis pins directly. The drill speedshould be as slow as possible to avoid excessive heatproduction, but still enable smooth pin advance-ment without excessive wobble (50 to 150 rpm). Apilot hole should be drilled using a slightly smallerdrill bit, prior to insertion of positive-threaded pins.Hand-drilling is not recommended as unavoidablewobble tends to produce too large a hole.

Local stresses on individual pins can be reduced by:■ Increasing the number of pins per fragment andspreading them as evenly as possible along thelength of each fragment;■ Using threaded pins, which have a larger area ofbone-pin contact that spreads the stresses;■ Using thicker (ie, stiffer) pins. Thinner pins bendmore and may overload the cis-cortex.

Inner layer of dressing. Polyurethane foam (Allevyn; Smith & Nephew) has been placedaround the pins to absorb any discharge and scrub sponges have been used to minimise soft tissue movement and swelling


Acrylic pin external fixation system

‘Kit size’ Pin shank diameter Connecting tubing Acrylic pack

APEF Small 1·6-2·4 mm 10 mm 50 mlMedium 2·4-3·2 mm 15 mm 100 mlLarge 3·2-4·0 mm 21 mm 150 ml

APEF SYSTEM SIZES

In the acrylic pin external fixation (APEF) system, thepins are set into acrylic columns rather than clampedto metal or carbon bars. The basic kit consists of adivided pouch containing liquid and powder compo-nents, which begin to set on mixing and can be pouredinto tubular moulds. Care must be taken to preventacrylic leaking out around the pins and setting on theanimal, which can cause burns. Appropriately sizedacrylic columns are of equal or greater stiffness andstrength to a comparable Kirschner-Ehmer system, aslong as sharp bends in the tube are avoided. Recently,epoxy putty has become available (Epoxy ESF Putty;Veterinary Instrumentation) which comes in a semi-solid form in a tube; the putty is kneaded for three tofour minutes to activate the components, prior tomoulding it around the end of pins to form a bar.

AdvantagesThe acrylic? tube or putty can be moulded to anyshape, allowing great flexibility in the direction ofpin placement. This is particularly useful in stabilisingjaw fractures, as the frame can be conformed to thecurved jaw, and pins angled to avoid tooth roots.

APEF system. The green clip is removed, and the liquid andpowder mixed. The tubing should be capped at one end(plugs are supplied) and the acrylic poured (or injected)into the tubing while it is still relatively liquid in order to ensure it is distributed along the full length. Airbubbles should be avoided, as pockets of air within the tubing will weaken the column

Epoxy putty used to link multiple pins into a ‘mini-fixator’,which has been applied to stabilise multiple metatarsalfractures in a cat

DisadvantagesThe frame cannot be adjusted after the acrylic orputty has set. Temporary clamps and a connectingbar (applied laterally to the empty acrylic tube) canbe used to maintain reduction and alignment untilpostoperative radiographs are taken, after which theacrylic can be applied. However, it is not possible tocheck clinical union without cutting the acrylic bar,which cannot then be easily reconstructed.

NB. Do not be tempted to cut costs by using a ‘blob’of acrylic to attach pins to a steel bar – this will frac-ture or loosen rapidly.

COMPLICATIONS

Most complications seen with external skeletal fixationare caused by poor technique. However, these are usual-ly minor, easily dealt with, and rarely produce a negativeoutcome. ■ PREMATURE PIN LOOSENING is by far the most commoncomplication, and results from a failure of the pin-boneinterface. Clinically, a loose pin causes pain, inflamma-tion and discharge from the pin tract, and leads toincreased lameness. Radiographically, a radiolucent lineis seen around the pin, as bone is resorbed and replacedby fibrous connective tissue. If the pin feels loose afterthe clamp is undone, it must be removed as it no longercontributes to the frame. If the most proximal or distal

pin loosens and is replaced, the new pin should be placedso that the fixator bridges the empty screw hole. ■ CONTINUED INSTABILITY causes further resorption andcan lead to infection or, in extreme cases, sufficient boneweakening to cause fracture. Loosening of a single pin isto be expected, but loosening of several pins suggeststhat the frame is too weak, or that the surgical techniquehas been poor. ■ PIN BREAKAGE is rare.■ CATASTROPHIC FRAME FAILURE occurs only if the requiredstrength of the frame has been seriously underestimated.■ PIN TRACT INFECTION. If the pin is stable, and only aslight discharge is present, this can be managed by apply-ing basic hygiene measures (ie, cleaning the area, as nec-essary, using sterile saline and a cotton bud). Infection is


(above) APEF fixator used to stabilise mandibular fracturesin a boxer. Note that the front ‘bumper bar’ dips ventrallybelow the jaw rather than protruding rostrally, whichwould make it more difficult for the animal to feed anddrink from a bowl. (below) Radiograph of a healed rostralmandibular fracture in a similar case to that picturedabove, showing placement of the pins at different anglesto avoid the tooth roots

most commonly due to coagulase-positive Staphylococcusspecies, and is predisposed to by leaving a loose pin inplace for an extended period of time. Major pin tract infec-tion is rare, and usually resolves when the pin is removed.Consequently, osteomyelitis is also uncommon. In severecases, infection can extend into the soft tissues and erodethrough a vessel, resulting in life-threatening haemorrhage.This has been reported with pins exiting the radius medial-ly, with damage to the median artery; in such instances,the pin must be removed and a pressure bandage applied. ■ RING SEQUESTRA are occasionally seen as a result ofthermal necrosis, typically from high-speed drilling ofdense cortical bone. Treatment involves removing the pinwhich is loose and curetting the tract using an oversizeddrill bit. Subsequent drainage leads to uneventful healing.

COMPARISON OF DIFFERENT SYSTEMS

KIRSCHNER-EHMER SYSTEMThe Kirshner-Ehmer system is cheaper than the Securosor IMEX-SK systems. However, its major limitation isthat the components are weaker than those of similarlysized Securos or IMEX-SK kits, and so more complexframe configurations (types II and III) are required forall but the most simple fractures.

In addition, there are some specific limitations associ-ated with the clamp design:■ Standard clamps cannot be added or removed from aframe without dismantling it;

Radiograph showing lysis and a periosteal reaction around a loose pin (arrows)

Pin tract complications. (left) Soft tissues have become swollen, causing impingement of theskin on the clamps and discharge from the more distal pin. (right) Minor pin tract infection.In this case, the pins remained secure, so the wound was cleaned daily using saline and acotton bud, and the tract closed uneventfully


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■ Positive-profile pins do not fit through standardclamps, thus restricting their use to the most proximal ordistal position in the frame;■ The two aforementioned limitations can be overcomeby using split clamps, although these are inherentlyweaker;■ Clamps are designed to fit a specific size of pin, and cannot be repeatedly tightened without deformingthem, thus reducing their lifespan (average four to fiveuses).

SECUROS SYSTEMThe Securos system has the following advantages:■ Clamps are designed to be clipped onto the connect-ing bar, thus permitting easy addition or removal ofclamps at any stage;■ The connecting frames are stronger;■ Guides are available for pre-drilling pilot holes andplacing full pins;■ ‘Axial dynamisation’ is possible using special clampsthat grip the pin but slide on the connecting bar. Thisallows axial loading, but protection against torsion,translation and bending.

IMEX-SK SYSTEMThe IMEX-SK system has the following advantages:■ Clamps allow any size or type of pin to be added orremoved at any stage;■ Single clamps can be modified to form an adjustablearticulation for transarticular frames;■ Carbon fibre connecting bars are available. These areradiolucent, lighter and considerably stiffer than steelbars;■ Axial dynamisation is not possible with the IMEX-SK system, but staged disassembly can be performed byeither:– Progressively reducing the stiffness of the connectingbars (titanium, carbon fibre, steel, aluminium in order ofdecreasing stiffness);– Replacing large clamps and rods with smaller ones(eg, at six weeks).

ReferencesEGGER, E. L. & HISTAND, M. B. (1993) Canine osteotomy healingwhen stabilised with decreasingly rigid fixation compared toconstantly rigid fixation. Veterinary and Comparative Orthopaedicsand Traumatology 6, 182MARTI, J. M. & MILLER, A. (1994a) Delimitation of safe corridors for the insertion of external skeletal fixator pins in the dog. 1. Hindlimb. Journal of Small Animal Practice 35, 16-23MARTI, J. M. & MILLER, A. (1994b) Delimitation of safe corridors for the insertion of external skeletal fixator pins in the dog. 2. Forelimb. Journal of Small Animal Practice 35, 78-85

Further readingPIERMATTEI, D. L. & FLO, G. L. (1993) Handbook of Small AnimalOrthopaedics and Fracture Repair. Philadelphia, W. B. SaundersKRAUS, K. H., TOOMBS, J. P. & NESS, M. G. (2003) External Fixationin Small Animal Practice. Oxford, Blackwell Science

Equipment suppliers■ KIRSCHNER-EHMER, APEF, AND EPOXY PUTTY

Veterinary Instrumentationwww.vetinst.com■ SECUROS

Orthomedwww.ortho-med.co.uk■ IMEX-SK Animalcarewww.animalcare.co.uk

Small† Medium Large

Kirschner-EhmerSingle clamp £10.00 £10.00 £10.00Single split clamp £14.30 £14.30 £14.30Connecting bar £3.52-4.20 £4.66-5.04 £8.10-15.67(stainless steel)Ellis pin £3.00 £3.00 £3.00Trochar pin £2.50 £2.50 £2.50

SecurosSingle clamp £9.50 £11.00 £11.00Connecting bar £1.50-2.00 £2.50-3.00 £2.50-3.00(stainless steel)Connecting bar – – Not yet available(carbon fibre)

IMEX-SKSingle clamp £10.50 £13.65 £16.80Connecting bar £3.90-4.30 – –(stainless steel)Connecting bar – £4.30-12.10 –(titanium alloy)Connecting bar – – £5.15-8.40(aluminium)Connecting bar – £4.40-12.40 £4.95-14.15(carbon fibre)

APEFPins £3.00 £3.00 £3.00Tubing £4.83 £6.03 £6.03Acrylic £16.00 £22.51 £30.91Epoxy putty? £7.50 (55 g) £15.00 (110 g) –

*Approximate cost (July 2004) in £sterling for basic equipment (not including VAT). The range ofprices is for connecting bars of different lengths. A large variety of pins are available, and costs arecomparable between the systems, and so have not been included.†Referred to as mini/miniature in the IMEX-SK system

COST COMPARISON* FOR EXTERNAL SKELETAL FIXATION SYSTEMS

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Practical Guide to Linear External