supracondylar femoral fractures in adult animals

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Vol. 22, No. 11 November 2000

Refereed Peer Review

FOCAL POINT

KEY FACTS

#Choosing appropriate orthopedicimplants and surgical techniques

is critical to the successful

management of supracondylar

femoral (SCF) fractures in adultanimals.

Supracondylar FemoralFractures in Adult

AnimalsUniversity of Tennessee

David A. Lidbetter, BVSc, MVS, CertSAS, MACVSc, MRCVS

University College Dublin

Mark R. Glyde, BVSc, MVS, MACVSc, MRCVS

ABSTRACT: Supracondylar femoral (SCF) fractures in adult animals present significantly

greater challenges to veterinary orthopedists than do fractures in immature animals in which

the bone breaks are usually type I or II Salter-Harris physeal fractures. In adult animals, SCF

fractures are often unstable because of their distal position and propensity to be comminuted.

Because of the composition of the distal femur, minimal bone stock is usually available for im-

plant placement. As a result, traditional implants such as intramedullary pins and dynamiccompression plates may not be adequate to stabilize fracture forces. A range of available im-

plants offers additional approaches to the management of this relatively uncommon fracture.

Femoral fractures are commonly repaired in small animals. Midshaft dia-physeal fractures are the most common femoral fractures, followed by frac-tures of the distal epiphyseum. Supracondylar femoral (SCF) fractures oc-

cur infrequently in adult animals.1 The major texts and veterinary scientificliterature cover the management of growth plate injuries in immature animalsand midshaft femoral fractures in adults in some detail; however, far less infor-mation is available on the management of the often more challenging distal frac-

tures.28

In humans, SCF fractures are a common fracture in which two distinctpatient populations exist: Younger people sustain these fractures as a result ofhigh-velocity trauma, and elderly people with osteoporosis often sustain themafter minimal trauma.920 Various orthopedic implants and techniques, includingintramedullary (IM) pinning, blade plating, buttress condylar plating, dynamiccompression plating, interlocking nailing, Zickel supracondylar nailing, anddouble plating, are employed in humans to repair the fractures.920

Management of distal femoral fractures in young animals is typically straight-forward because of the simple nature of the fracture and the innate potential ofyoung animals to heal rapidly. The fractures normally occur through the weakzone of hypertrophy in the physis; the surface of the fracture often interdigitatesin a W shape, giving the repair some inherent stability.21

CE

V

I SCF fractures may be more

challenging surgically in adult

dogs than in immature animals

in which the fracture tends to

be through the growth plate.

I After the fracture is thoroughly

assessed, implants and surgical

techniques should be tailored to

individual fracture configurations.

I Traditional repair methods such

as intramedullary pinning and

standard bone plating may not

provide ideal stability for SCF

fractures.

I Alternative devices should beconsidered to stabilize SCF

fractures in adult animals.


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In adult dogs, SCF fracturescan present substantial challengesbecause of the unique composi-tion of the distal femur and thefact that the fractures are often

more comminuted and unstable(Figure 1). These fractures aredifficult to manage because ofthe presence of large momentsand forces acting on them withshort segments of bone distally.SCF fractures are located near anarea of high motion due to thepresence of the knee joint andhave a small distal target for im-plant placement that is eccentri-cally placed to the bone column.

In adult animals in which bio-buttress formation is slow, maxi-mum stability (which is difficultto achieve because of the smalleccentric distal target) must beobtained from the implant usedto repair the fracture. Recently,veterinary orthopedists have seenan influx of new repair devices that can be used tomanage these more difficult fractures (Table I).

ANATOMY

The shaft of the distal femur is composed of hardcortical bone, typical of the diaphysis of long bones.The femur begins to flare in its central midshaft regionand is widest in the supracondylar/epicondylar area.The condylar bone is spongy, being primarily cancel-lous with a thinner cortical rim. Cranially, the condylarregion of the femur is bordered by the medial and later-al condylar ridges and trochlear sulcus, which are cov-ered by hyaline cartilage.22 Distally, the condyles curvecaudally with the intercondylar notch, separating themedial and lateral condyles. The intercondylar notch isthe origin of the cranial and caudal cruciate ligaments.

The stifle joint is a hinge joint with limited ability torotate and is primarily stabilized by the cruciate liga-ments. Primary mediolateral stability is from the collat-eral ligaments. The lateral collateral ligament attachesthe caudal distal femoral condylar region to the head ofthe fibula, and the medial collateral ligament attachesthe medial epicondyle to the proximal medial tibia.22

More cranially on the lateral side of the stifle, the longdigital extensor tendon attaches onto the distal femoralcondyle.

The relevance of the local anatomy is that SCF frac-tures result in minimal bone stock in which to place

implants to stabilize the fracture.The bone tends to have poorerholding potential because of itsmaterial properties; however, itdoes have a greater surface area

for fracture healing to occur. Im-plant placement must also avoidkey structures (e.g., articular car-tilage, collateral and cruciate lig-aments).

CLINICAL FINDINGSAND DIAGNOSIS

Animals with SCF fracturescommonly present in an unsta-ble condition and may have suf-fered concurrent injuries. They

are usually nonweight-bearingin the affected leg and will haveconsiderable femoral swelling.Thorough physical, orthopedic,and neurologic examinations arenecessary. Assessment of the cru-ciate and collateral ligaments isespecially important. Instability

from the fracture and local swelling can make assess-ment difficult. The cruciate ligaments in these animalsshould be assessed directly by inspection via arthroto-my during fracture repair. Initial diagnostics should in-

clude a complete blood count, chemistry panel, urinal-ysis, and chest and abdominal radiography. Continuouselectrocardiography for 24 to 48 hours is advised.

FRACTURE CONFIGURATIONAND NOMENCLATURE

Fracture classification systems, which are based onthe patterns of large numbers of fractures, have beencreated for humans. These systems aid in rationalizingthe use of a particular treatment, evaluating outcome,and prognosticating. Although such systems have beendevised in veterinary orthopedics, they have not gained

widespread recognition and are not used universally.23,24

For reasons of simplicity, SCF fractures can be classifiedas supracondylar, condylar, and supracondylar/inter-condylar. Commonly used descriptive terms includesimple, multiple, comminuted, and open or closed.

SURGICAL APPROACHOccasionally, SCF fractures that are incomplete or min-

imally displaced may be treated closed without any surgi-cal approach. With the introduction of image intensifiersin veterinary surgery, closed reduction may be increasinglyused with implants placed percutaneously. Most often,

Small Animal/Exotics Compendium November 2000

D I S T A L F E M U R I I M P L A N T P L A C E M E N T I C R U C I A T E L I G A M E N T S

Figure 1Lateral radiograph of a comminuted su-pracondylar femoral fracture.


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however, either a full-open approach, mini-approach, oropen-but-do-not-touch approach is employed.25,26 Typical-ly, because of the instability of these fractures and their dis-tal location, an approach to the shaft of the femur is com-bined with a lateral approach to the stifle as described byPiermattei and Greeley.27

An alternative technique, which provides excellent

exposure with only a minor increase in morbidity, com-bines the approach to the lateral femur with a tibialcrest osteotomy and proximal reflection of the straightpatella ligament and quadriceps group.10,27 The firmlyattached periosteum and joint capsule should be elevat-ed from the distal lateral condylar region when a boneplate repair of the femur is applied.

Compendium November 2000 Small Animal/Exotics

R E P A I R D E V I C E S I L A T E R A L A P P R O A C H I Q U A D R I C E P S

TABLE I

Devices Used to Repair Supracondylar Fractures in Adult Animals

Repair Devices

Intramedullary pins

Crossed K-wires

Rush pins

Lag screws

DCP

Reconstructionplate

Plate/rod

Modified type IESF

Customized hookplate

Interlocking nails

Tibial headcompression plate

Hybrid circularESF

Indications

Use as adjunct fixation

Cats; small dogs; transverse,short oblique fractures

Cats; small dogs; transverse,short oblique fractures

Small chondrodystrophoidbreeds of dogs; very distaltransverse fractures

Many SCF fractures,particularly more proximal

fractures

Cats; small- and medium-sizeddogs; chondrodystrophoidbreeds of dogs

Most breeds and sizes of dogsand cats; comminuted andcortical defect fractures

All breeds and sizes of dogs andcats; comminuted, open SCFfractures

Most breeds and sizes of dogs;most fracture configurations

Most breeds and sizes of dogsand cats; more proximal SCFfractures

Large-breed dogs; most fractureconfigurations

Most SCF fractures; mostbreeds and sizes of dogs and

cats; very distal fractures

Relative Contraindications

Most SCF fractures

Comminuted, cortical defectfractures

Comminuted, cortical defectfractures

Nonchondrodystrophoidbreeds of dogs; comminutedfractures

Chondrodystrophoid breedsof dogs; very distal fractures

Large dogs; comminuted orcortical deficit fractures

Some cats and small dogs;very narrow medullary canals

SCF fractures with anarticular component

Use extra care with cats andsmall dogs

Chondrodystrophoid breedsof dogs; some cats with verydistal fractures

Animals weighing


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TREATMENTThe goals of fracture repair are as follows: rigid ana-

tomic reduction and fixation, when possible; anatomicreduction of the joint surface and rigid fixation (articu-lar fractures); reduction and stabilization or buttressing

of the metaphyseal region (comminuted fractures);restoration of normal axial alignment and length; andearly controlled motion.

Intramedullary Pinning, KirschnerWiring, or Rush Pinning

Crossed Kirschner wiring (K-wiring), which is themainstay of distal femoral fracture repair in immatureanimals, has limited applications in SCF fractures inmature dogs, although its use may be indicated insmall- or toy-breed dogs or cats. The availability ofbone stock in these animals may be so small that it pre-

cludes the use of other implants. Contact between thefracture fragments must be achievable. A lateral ap-proach can be made to the distal femur, and the caudal-ly displaced fracture can be reduced and maintained

with reduction forceps. Care should be taken to avoidcrushing the bone in young adult animals. Fine, plainK-wires should be placed in cross-fashion either fromthe medial and lateral sides or both from the lateral side(Figure 2).2-8,2832 The pins may be placed distal to prox-imal or proximal to distal, depending on personal pref-erence. In small adult animals with transverse distalSCF fractures in which larger, stronger implants may

not fit, K-wiring can be a simple, effi-cient means of successful fracture re-pair.

In general, IM pinning is not recom-mended as a reliable means of fracture

stabilization of SCF fractures in adultanimals. In one study,33 159 primarilyimmature cats and dogs reported goodresults using IM pins normogradedfrom the stifle. Single IM pinning ap-pears to work best in young cats withdistal femoral fractures because of theirrelatively straight femurs and small size.However, IM pinning alone is oftenless than satisfactory for treating SCFfractures in adults. The technique re-sults in poor distal bone-holding pur-

chase and strength, and the pins are of-ten driven into the proximal condylarregion, immediately adjacent to thefracture line instead of more distally indeeper condylar bone. Single IM pinsovercome rotational forces poorly, of-ten resulting in inadequate stability.34

Pins that are stacked probably do not gain greater pur-chase distally and do not achieve greater cortical contact.Stacked pins are technically more difficult to place andoften do not improve stability (Figure 3). Instead of beingused as a sole implant, IM pinning can be incorporated as

a valuable adjunct to external fixation or bone plating be-cause it overcomes bending forces.Rush pinning can be an excellent means of stabilizing

these fractures in cats and small- to medium-sized dogs,particularly when the fracture line is transverse or shortoblique. Rush pinning allows for three points of fixa-tion, providing greater tension and stability. Rush pinsare introduced from either side of the distal fragment atan acute angle after the pins have been prestressed.34

The points are beveled so as not to engage the cortex.Awls to start the guide holes and driver extractor toolsare required for placement. Where comminution or

cortical deficits exist, the pins may not provide suffi-cient stability and fracture collapse can occur. Rushpinning requires specialized equipment and training.IM cross-pinning has also been described.35

Lag ScrewSome SCF fractures may be extremely distal because

of the marked bow of the femur in chondrodys-trophoid breeds. Occasionally, there may be room onthe distal fragment for only one implant (e.g., one boneplate screw hole, one fixator pin) to be placed. Insteadof using crossed K-wires in some of these fractures, lag


B O N E S T O C K I F R A C T U R E S T A B I L I Z A T I O N I B O N E P L A T I N G

Figure 2Craniocaudal postoperativeradiograph of a supracondylar femoralfracture repaired with crossed Kirschner

wires.

Figure 3Craniocaudal radiograph of asupracondylar fracture repaired withstacked intramedullary pins. Note thepoor purchase of distal metaphysealcancellous bone predisposing to insta-bility.


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screws may be positioned in parallel fashion from thecranioproximal femur to the caudodistal condylar re-gion of the femur (Figure 4). This technique is usefulonly in chondrodystrophoid breeds when other im-plants do not fit. Because the strength of this type of re-pair is limited, it should only be used in certain cases.

Dynamic Compression PlateIn midshaft femoral fractures, conventional and lim-ited-contact dynamic compression plating is often cho-sen because of the ease of approach, minimal contour-ing needed to apply the plate, and rigid stability of theplate. In proximal SCF fractures, dynamic compressionplating is also used for all sizes and breeds of adult ani-mals. With more distal SCF fractures, insufficient distalbone stock typically limits screw placement. Two screwsin each fracture fragment are the minimum require-ment for stability. Ideally, at least three screws shouldbe placed, but it is often impossible to place even two

screws.36

Because dynamic compression plates (DCPs)can only be bent in two planes, they cannot be con-toured caudally with the natural bow of the femur.

Apart from reducing the number of potential screwholes, plates often overrun the distal femur protrudingpast it, impinging on the lateral edge of the trochleargroove and patella fibrocartilage (Figure 5). DCPs mayalso interfere with closure of the joint capsule and sur-gical wound and perhaps, most importantly, may dis-turb the dynamics of the patella and quadriceps mecha-nism. The patella may be luxated laterally or displaceddorsally as a result of the position of the plate.

Reconstruction PlateReconstruction plates are ideally suited to fractures of

the distal femur because of their unique ability to be con-toured in three planes. The plates are available in 2.7, 3.5,

and 4.5 mm and have notches manufactured into thembetween screw holes to allow them to be bent. Recon-struction plates are not extensively cold worked and areleft in the annealed or soft state, thus giving them theproperty of ductility.36 In humans, these plates were initial-ly designed for maxillofacial fractures but also have beenused extensively in pelvic fracture repair. These anatomicareas in humans are usually under minimal strain; there-fore, the plate has some protection.10 These plates are notdesigned to withstand the forces of weight bearing andshould not be used to buttress fractures with bone deficitsand marked instability.36 These plates can easily undergo

cycling and bend, or they can fatigue and break.Reconstruction plates can be bent caudally and flaredoutward to contour to the distal femur and have beenused for SCF fractures in small animals (Figure 6). Thiscan increase bone purchase by increasing the number ofscrews engaging the bone and preventing plates fromextending distally, interfering with the stifle.

Reconstruction plates ideally are used in smalleradult animals in which there can be reconstruction ofthe bone column and sharing of the load through thebone and plate when the animal bears weight on thelimb. These plates are particularly useful in chon-


C O R T I C A L L A G S C R E W S I S C R E W P L A C E M E N T I P A T E L L A

Figure 4A Figure 4B

Figure 4(A) Lateral radiograph of an extremely distal supracondylar fracture in achondrodystrophoid dog. (B) Lateral postoperative radiograph showing repair usingtwo 2.7-mm cortical lag screws.

Figure 5Lateral postoperative radio-graph of a supracondylar fracture re-paired with a 3.5-mm dynamic com-pression plate. Inadequate stability isachieved because only four cortices areengaged and the plate overruns the dis-tal femur.


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drodystrophoid breeds in which marked caudal bowingof the condylar region precludes using standard boneplates in more distal fractures.36When only one or twoscrews are placed in the distal fragment, crossed K-

wires should be used for additional stability.

PlateRod Combination

The platerod technique attempts to synergize theactions of IM pins and bone plates.8,25,26,3739 This tech-nique is especially useful in highly comminuted frac-tures or when a significant cortical deficit that cannotbe anatomically reconstructed is present (Figure 7). Anopen approach to the femur and stifle should be made,and an IM pin can be placed either retrograde or nor-mograde in order to reduce the fracture and aid align-ment. The trochlear sulcus and greater trochanter canbe used as landmarks to avoid rotation of the stifle oranteversion of the femoral neck and head. The limbshould be checked for varus deformation before a plate

is applied to the lateral femur. The plate neutralizes ro-tational, bending, and axial forces while the pin, whichis placed centrally in the bone, protects the plate andguards against bending.25,26,3739

Although this technique involves a significant num-ber of implants, no attempt should be made during re-pair to anatomically reconstruct multiple small fracturefragments. This biological approach to the repair triesto minimally disrupt the already fragile blood supply tothe fracture.25,26,38A bone graft should also be placed. Aminimum of three monocortical screws and one bicor-tical screw should be used on either side of the frac-

ture.8 Guidelines for pin size and screw number havebeen published; a pin diameter of no greater than 50%of the medullary canal at its narrowest point is recom-mended. Because screw placement in the diaphysis isoften extremely difficult, it may only be possible toplace screws in the metaphyseal regions.

Modified Type I External FixatorThe modified type I external skeletal fixator (ESF),which can be used in all cats and dogs, can be appliedto most SCF fractures, including those that are trans-verse, comminuted, or very distal. No implants areplaced at the fracture site and either a complete openapproach, a limited approach, or closed reduction andframe application can be used. This type of implant hasthe potential for less soft tissue and associated vasculardamage. Initially, in veterinary practice, the use of ESFs

was primarily reserved for the distal limb with less usein proximal limbs owing to the larger mass of soft tissue

and impingement of the body wall medially. The use offixators in the femur and humerus in cats and dogs hasincreased because of the introduction of modified andmore complicated strategies and frames.

Simple type I ESFs can be used in SCF fractures;however, gaining adequate purchase in the distal frag-ment is not always feasible. Placing one or two centrallythreaded positive-profile full pins in the distal condylarregion from lateral to medial allows the use of a bent,additional connecting bar to be passed from the medialside of the distal femur to the lateral proximal femur(Figure 8).40,41 This increases the stiffness of the frame


C O M M I N U T E D F R A C T U R E S I O P E N A P P R O A C H I P I N D I A M E T E R

Figure 6Lateral radiograph of supra-condylar fracture repair using a 2.7-mmreconstruction plate.

Figure 7A Figure 7B

Figure 7Craniocaudal radiographs of a highly comminuted midshaft supracondylarfemoral fracture (A) and repair using a plate rod technique (B).


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and minimizes fracture instability and pin loosening. Itis advisable to use another one or two half-pins in thedistal fragment, if possible, and four half-pins proxi-mally. Positive-profile pins are used because of theiradded cortical bone contact, increased pin pull-outstrength, and lower incidence of pinbone interfaceproblems.4244 This frame is well tolerated by cats and

dogs and results in minimal to no body wall contactwith the frame.45

Alternatively, an acrylic frame can be used in thehumerus to connect the lateral type I pins across thedistal femur to the medial side, then continuing proxi-mally over the thigh to the lateral proximal aspect.46

The bending strength of the frame is improved by plac-ing an IM pin in the shaft of the femur and then con-necting it to the main lateral frame in a tied-in con-figuration.47 In SCF fractures, fixators are often placedvia an open approach because of the difficulty in reduc-ing the fractures closed. If an open approach is made to

a comminuted SCF fracture, it is usually an open-but-do-not-touch approach in which the proximal and dis-tal bone columns are reduced, the hip and stifle jointsare aligned, and no attempt is made to anatomically re-construct the bone column.25,26

The presence of pins in the distal femur can cause ir-ritation to the joint capsule, retinaculum, and soft tis-sue. The stifle, being a high motion area, can add tothe irritation. The quadriceps muscle should be avoid-ed, and soft tissue entrapment can be minimized by us-ing retraction or drill guides. Morbidity associated withthe pins can include pin tract discharge and infection,

pin loosening, and decreased stifle range of motion andleg usage.4244 Although significant complications areuncommon, veterinarians and owners should monitorand clean the skin surrounding the pins, encouragecontrolled physical therapy, and monitor radiographsfor evidence of pin loosening.

Customized Hook PlateA customized hook plate has been developed recentlyfor use in metaphyseal fractures when minimal bonestock is a complicating consideration.48 The techniqueinvolves bending a standard DCP and fashioning sharp,pointed hooks with a hacksaw blade (Figure 9). Thismodified implant can be useful in SCF fractures withsmall distal targets and can have some advantages overconventional plates. The same number of screw holescan be used as in a DCP, with the addition of the fash-ioned hooks. Two parallel holes set the width of theplate apart should be drilled into a distal portion of the

femoral fragment before gently hammering the hooksinto the bone (Figure 10). Drill diameter should beslightly larger than that of the hooks. The fractureshould be reduced and a screw hole in the proximalfracture fragment filled, securing reduction. The re-mainder of the screw holes in the distal and proximalfragments should be drilled and filled.

In humans, a dynamic compression screw may beused to compress SCF/intercondylar femoral fractures,or an AO (Arbeitsgemeinschaft fur Osteosynthesefra-gen) blade plate can be used to provide increased sur-face area contact of the plate in distal bone.10,11,13,17


P O S I T I V E - P R O F I L E P I N S I M E T A P H Y S E A L F R A C T U R E S I M O D I F I E D I M P L A N T

Figure 8A Figure 8B

Figure 8(A) Supracondylar femoral (SCF) fracture treated with a modified type Iexternal skeletal fixator (ESF) with only a lateral connecting bar. (B) SCF fracturetreated with a modified type I ESF with both lateral and medial connecting bars.

Figure 9Customized hook plate froma regular dynamic compression plate.


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These implants are generally too large to use in mostanimals; however, the customized hook plate followssimilar principles to that of the blade plate. The tightsecurity of the hooks is less important than is their con-tact in the bone.10 Screws can be placed through thehooked area, thus the number of screws in the distalfragment is not reduced yet the points of contact areincreased.48 The drawback of this technique is that be-cause an aiming jig is not available for screw placement,

moderate force may be needed to hammer the hooksinto the bone holes. This does not, however, detractsignificantly from the technique. Similar to the DCP,the modified hook plate may cause difficulty in closingthe joint capsule and can affect the patella if the plate ispositioned too close to the trochlea ridges.

The technique is adaptable and has been used suc-cessfully in medium to large dogs. Care may be neededin small dogs and cats to ensure adequate width is pres-ent for the hooks to be placed distally.

Interlocking Nails

Adapted from human medicine, the Dueland inter-locking nail system is designed for veterinary patients.49

The nails are solid, surgical stainless steel with screwholes at either end. An open approach to the femur isusually made and limited muscle reflection is necessary.Screws should be inserted through the bone to engagethe nail, thereby preventing rotation of the fracture andaxial collapse (Figure 11).4951 Interlocking nails (ILNs)offer the advantage of positioning the implant centrallyin the bone, thereby providing excellent bendingstrength. Three nail models are available with lengthsfrom 140 to 230 mm. Nail diameters range from 4.7 to

8 mm and accept 2.0-, 2.7-, 3.5-, and 4.5-mm screws.49

The largest nail that fits the medullary canal should bechosen. The nail should be long enough to place thescrew holes 2 cm from the fracture site, and nails ofsimilar length and contralateral limb radiographsshould be used to ensure that the pin is seated in distalmetaphyseal cancellous bone.4951 The distal fragmentin SCF fractures may need to be overreduced. The nailsare usually placed in normograde fashion; however, an

opening in the proximal cortex may be made using aseparate pin in a retrograde fashion.Because the nails have been customized for animals,

problems with aiming and executing the techniquehave been ameliorated. Nails are now made with moredistal screw hole placement so that they can be appliedto SCF fractures. An obstacle with this technique is theinability to lodge the pin distal enough to gain screwpurchase below the fracture line; occasionally, a singlescrew hole below the fracture line is necessary. Thisshould not significantly alter stability at the repairsite.51

The ILN is an adaptable system requiring specializedequipment, which can be used for most sizes andbreeds of adult animals. It can be used in transverse andcomminuted fracture patterns. Complications with thetechnique include problems with screw aiming andplacement, breakage of the nail at the screw hole, andsciatic nerve damage if the nail protrudes from the in-tertrochanteric fossa.49

Tibial Head Compression PlateThe tibial head compression plate is primarily for use

in dogs weighing more than 25 kg. The design of the


B L A D E P L A T E I A X I A L C O L L A P S E I M E D U L L A R Y C A N A L

Figure 10Customized hook plate placed using predrilledholes and a mallet.

Figure 11Surgical application of an interlocking nail.


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plate allows for more screws to beplaced in the distal fragment below theSCF fracture line. The plate, whichhas been precontoured to fit the proxi-mal lateral tibia in humans, was de-

signed for complex fractures of the tib-ial plateau.10,52 The plate has the samethickness as the 3.5-mm broad DCP,although it is 2 mm wider. The plate isavailable with five, seven, or nine DCPshaft holes, which accept 4.5-mm cor-tical screws, and is available in 118- to240-mm lengths. One end of the plateis flared to a maximum width of 26mm and curves in a convex fashionabout 13 (Figure 12).53 The flaredhead thickness gradually reduces cen-

trally to 1.57 mm and has three roundholes in a triangular pattern.53 Theround holes are separated from regularDCP holes by an oval hole that can actas a positioner when the first screw isplaced. The round head holes accept 4.5-mm cortical,6.5-mm cancellous, and cannulated screws.

When the plate is placed in the opposite fashion toits use on the tibia (i.e., a right-sided tibial plate is placedon the left femur upside down), it mimics the caudalbow of the femur and its distal flaring.53 The advantagein SCF fractures in larger dogs is that more screws can

be placed in the distal fragment when there is minimalbone stock because of the unique shape of the plates,neck, and head (Figure 13).

Hybrid Circular External Skeletal FixatorOver the past 10 years, there has been increased at-

tention in veterinary medicine to the use of circularESFs for fracture repair, bone lengthening, and gradualcorrection of angular limb deformities.5456 Most reportsconcentrate on the use of full rings for tibial and ra-dius/ulna fractures.55 In the humerus and femur, fullring constructs cannot be used because of the presence

of the body wall.Hybrid circular fixators combine one or two fullrings attached to the distal femoral fragment and arelinked to a lateral connecting bar where half-pins simi-lar to a type I external fixator are used.57 The full ringsallow two or more small-diameter wires or pins to beplaced percutaneously; these can be tensioned by a de-vice that increases the bending stiffness of the wires.Circular fixators provide similar torsional bending andshear resistance as do type I external fixators.57 There isless axial stiffness and increased continual micromotionat the fracture site when the animal is walking, which is

conducive to bone healing.57

Hybrid circular fixators, which canbe used in all breeds and sizes of dogsand cats, have an advantage over con-ventional external fixators in SCF frac-

tures. Because the pins are so small,more can be placed in a finite area;thus more cortices can be engaged inthe case of very distal fractures.54,55

Overall stability of the frame can beincreased by using the smallest-diam-eter ring, allowing for 1 to 2 cm be-tween the ring and skin for swelling;placing two parallel rings, if possible;increasing the number of wires perring; placing wires as close to 90 toeach other as possible; using tear-drop

shaped wires; and using positive pro-file half-pins in the proximal frag-ment.5459

Hanging of the limb operativelyhelps aid reduction and preplanning;

partially constructing the frame preoperatively can helpreduce surgical time. As with the ESF, the hybrid circu-lar fixator can be placed after closed reduction or after alimited approach. The hybrid circular fixator is anadaptable technique that requires specialized equip-ment and training.

SURGICAL PITFALLSWhen fracture fragments cannot be reduced anatom-ically, the femoral neck must be maintained at the cor-rect angle with respect to the stifle or a change in theangle of anteversion/retroversion at the coxofemoral

joint will occur. This may lead to progressive degenera-tive joint disease, dysplasia, or predisposition to cox-ofemoral luxation.

Appreciation of the normal anatomy of the lateralsurface of the femoral shaft is essential. From slightlyproximal to the midshaft, the bone begins to flare and

widen. If this contour is not accounted for in the plate,

the limb will be plated with a varus deviation and resultin an incongruity in joint alignment, which may alsoresult in lameness or degenerative joint disease. Radiog-raphy of the contralateral leg can aid in avoiding thismistake when contouring the plate.

Distal femoral fractures usually require an approachto the lateral stifle if internal implants are to be placed.

As a result, the lateral retinacular tissue of the patellaand soft tissue support is divided. If the implant ex-tends to the distal lateral limit of the femur or past thefemur, the potential exists that the patella will not bestabilized correctly at closure, resulting in laxity. This


T I B I A L P L A T E I F U L L R I N G S I H A L F - P I N S I C O R T I C E S

Figure 12Lateral tibial head plates.


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can lead to luxation or abnormal wear. In addition, itcan be difficult to adequately close the joint capsule be-cause of the presence of the implant. The common per-oneal nerve, which lies caudal to the lateral fabella onthe medial surface of the biceps, must be visualized be-fore fracture repair to prevent iatrogenic damage.

POSTOPERATIVE REHABILITATION

Supracondylar femoral fractures predispose the ani-mal to soft tissue complications. Quadriceps contrac-ture and tie-downs, which are seen more frequently inimmature animals with fractures, can also occur in ma-ture animals.60 Often, the quadriceps may be damagedby the trauma involved in creating the SCF fracture.

After open surgical repair, the muscle is prone to un-dergo fibrosis and to scar to the underlying periosteum.Signs of quadriceps contracture begin subtly and in-clude decreased limb usage, muscle atrophy, pain, stiff-ness, and a reduced range of stifle motion. This condi-tion can rapidly progress to rigid hyperextension of the

affected leg with reduced flexion of both the stifle andthe hock. The quadriceps becomes firm and severely at-rophied.

After quadriceps contracture has begun, the processcan be difficult to reverse; therefore, prevention is oftenbetter than cure.61A physical therapy program must beinstituted soon after surgery. Rigid surgical stabilizationand adequate analgesia are required.

Following surgery, the limb should be iced, the cir-cumference measured, and range of motion assessed

with a goniometer.62 If available, force plate analysis canbe used to document weight-bearing status. This base-

line data can be used throughout the recovery period toquantify progress. Early use of the limb is of paramountimportance; therefore, range-of-motion exercisesshould be performed daily. The limb should be iced be-fore each session and massaged before beginning vigor-ous physical therapy. Exercises can include sit-stand,short leash walks, treadmill walking, or walking up in-clines. Supervised hydrotherapy in a bath or underwa-

ter treadmill can begin after suture removal. At dis-charge, owners must be thoroughly educated regardingcare and procedures, and regular follow-up visits shouldbe encouraged.

To avoid soft tissue disease, active physical therapymust be continued until fracture healing is completed.Further therapy after this time will help reverse muscleatrophy and improve long-term limb function.

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G O N I O M E T E R I F O R C E P L A T E A N A L Y S I S I H Y D R O T H E R A P Y

Figure 13A Figure 13B Figure 13C

Figure 13Lateral postoperative (A) and craniocaudal (B) radiographs in an adult German shepherd of a supracondylar femoralfracture repaired with a lateral tibial head plate. (C) The lateral tibial head plate in situ.


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About the AuthorsDr. Lidbetter is affiliated with the Department of Small Ani-mal Clinical Sciences, University of Tennessee, Knoxville.

Dr. Glyde is affiliated with the Department of Veterinary

Surgery, University College Dublin.

supracondylar femoral fractures in adult animals

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