Young, male neutered, obese, lame?: Non-traumatic fractures of … · observed in neutered animals. In cases of spontaneous capital physeal fracture, both hindlimbs may be affected

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doi:10.1016/j.jfms.2011.05.007

498 JFMS CLINICAL PRACTICE

C L I N I C A L R E V I E W

Journal of Feline Medicine and Surgery (2011) 13, 498–507

Clinical Practice

Pilar Lafuente DVM PhD Dipl ACVS/ECVS MRCVS

Royal Veterinary College,Hawkshead Lane, Hatfield,Hertfordshire AL9 7TA, UKEmail: [email protected]

Pilar Lafuente

YOUNG, MALE NEUTERED, OBESE, LAME?Non-traumatic fractures of the femoral head and neck

Onset – chronic and insidious

Road traffic accidents and falls are frequent causes of a variety of bonefractures, with the pelvic limb being commonly affected.1,2 However,some feline fractures are not caused by traumatic incidents, and have amore chronic and insidious onset. Although fractures of the femoralhead and neck can be caused by trauma, this review will focus prima-rily on spontaneous capital physeal fractures (also known as felineslipped capital physis or feline physeal dysplasia syndrome), andpathological fractures of the femoral neck secondary to metaphysealosteopathy. These conditions have many features in common – not least that they affect young, male neutered, obese cats – and aclear differentiation between the two may be difficult.

Anatomy of the proximal femur

The proximal femur contains two growth plates: the capital physis andthe growth plate of the greater trochanter. The former is responsible forapproximately 30–40% of the longitudinal growth of the femur in smallanimals, while the latter contributes to normal development of the shape of the proximal femur but not to the length of the bone.3The capital epiphysis has a semicircular shape, and it articulates with the acetabulum to form the coxofemoral joint. The capital physisin the immature cat (and dog) has an L-shape contour that facilitatessurgical reduction and stabilisation of capital physeal fractures andseparations. This growth plate usually closes at 30–40 weeks of age inintact cats.4

Blood supply to the femoral head in small animals depends on vessels forming an intra-articular subsynovial arterial plexus near theedge of the articular cartilage around the femoral head. This vascularring is nourished principally by the lateral and medial femoral circum-flex arteries, and to a much lesser degree by the caudal gluteal arteryand iliolumbar artery.5–7 This vascular network crosses the peripheralborder of the physis to supply the capital epiphysis.3 In cats under 7 months of age, a substantial blood supply to the femoral head epi physis is provided by a vessel in the round ligament.6

Patient group Young, maleneutered, obese cats arepredisposed to sustainingspontaneous capitalphyseal fractures, as well as fractures of thefemoral neck secondary tometaphyseal osteopathy.Practical relevance Although femoral head andneck excision generally leads to adequate limbfunction, and is appropriate for chronic fractures, it is a salvage procedure and irreversible. Ideally, for acute capital physeal fractures an attemptshould be made to stabilise the fracture and savethe coxofemoral joint. This requires early detectionof the femoral fracture.Clinical challenges Orthopaedic examination incats can be challenging. Yet thorough assessmentis needed to allow localisation of the pathology tothe hip joint, and to rule out other orthopaedicconditions such as cranial cruciate ligamentrupture. Stabilisation of these types of fracture may also prove challenging. Audience This review is aimed at generalpractitioners who have some experience inorthopaedic surgical procedures, as well as those simply wishing to expand their knowledge of feline orthopaedic conditions.

ractures of the femoral head and

neck should be a differential

diagnosis for any young feline

patient presenting with hindlimb

lameness/weakness,

whether or not associated

with a traumatic event.

mailto:[email protected]

http://dx.doi.org/10.1016/j.jfms.2011.05.007

http://dx.doi.org/10.1016/j.jfms.2011.05.007

498_507_Lafuente_OK:FAB 8/6/11 14:39 Page 499

JFMS CLINICAL PRACTICE 499

REV IEW / Conditions of the femoral head and neck

Histologically, the growthplate of normal immature catscontains several zones:8,9

✜ Reserve zone In thiszone, just adjacent to the epiphysis, thechondrocytes are roundand scattered singly or inpairs, and surrounded byabundant cartilaginousmatrix. Cell division andmatrix production takeplace at a slow rate.

✜ Proliferative zoneChondrocytes areflattened in a transversedirection and are arrangedin columns. Cell division is the predominant function of this layer.

✜ Hypertrophic zone Chondrocytes are polygonal in shape and contain abundant cytoplasmicglycogen. Their size might reach eight-fold that of a normal cell, so the amount of matrix betweencells is markedly decreased. This zone is the weakest and, in experimental studies, has beenshown to be the most likely to fracture following trauma.

✜ Calcification zone The hypertrophic chondrocytes degenerate and the space they wereoccupying is invaded by new vascularisation. The process of calcification starts in this zone.

T h e g r o w t h p l a t e

The growth plate

is a weak area

and physeal

fractures are

common in

immature

animals. Closure

following physeal

injury is a risk

that could lead to

bone shortening

or deformities.

Any fracture through a

growth plate has the

potential to prematurely

close that growth plate

and affect growth.

However, this is more

common with type V

Salter-Harris fractures.

Images by Dr Frank Gaillard (http://www.frankgaillard.com)

Image courtesy of Dr Andrew Pitsillides

Salter-Harris classification of physeal fractures9

Type I fractures involve separation ofthe epiphysis from the metaphysis atthe growth plate, and frequently occurthrough the hypertrophic zone. Thesefractures are most common in theproximal humerus, and proximal anddistal femur

Type IV fractures run from the epiphysisthrough the growth plate and into themetaphysis. These are also articularfractures and occur in the distalhumerus and femur

Type II fractures occur through the growth plate and a corner ofmetaphyseal bone. A commonpresentation is in the proximal tibia

Type III fractures occur through theepiphysis and part of the growth plate,but the metaphysis is not affected.This type of fracture is an articularfracture and frequently affects thedistal humerus

Type I

Type IV

Type II

Type V fractures involve compressionof the growth plate with end of growthpotential. The distal ulna is the mostcommon location for this fracture

Type V

Type III

Reserve zone

Proliferative zone

Hypertrophic zone

Calcification zone




FIG 1 Ventrodorsal radiograph of the pelvis of a young catwith bilateral spontaneous capital physeal fractures (arrows). Courtesy of Dr Silke Stein

Non-traumatic conditions of the femoral head and neck

Spontaneous femoral capital physealfracturesIn the absence of a traumatic event (see box),fractures through the capital physis of thefemur usually affect cats that are maleneutered, obese and younger than 2 years of age, and they may be bilateral (Fig 1).3,12–14

These cats generally present with acute orchronic hindlimb lameness and, of course, nohistory of trauma. The patient is usually reluc-tant to jump, and pain, decreased range ofmotion and crepitus can be observed onmanipulation of the coxofemoral joint. Whileboth hindlimbs may be affected simultaneous-ly, a spontaneous fracture may develop in thecontralateral limb later on. Radiographicstudy of the affected coxo femoral joint revealsdisplacement of the femoral epiphysis in rela-tion to the meta physis. This incongruency isbest visualised when radiographs are takenwith the limbs in a ‘frog-legged’ position, asthe joint capsule is not tightened and thus thefracture is not reduced into position.

McNicholas and coworkers identified fourrisk factors in the development of sponta-neous femoral capital physeal fractures:14

✜ Sex Males are at increased risk ofsuffering from this condition.

✜ Reproductive status Being neutered is a predisposing factor in cats.

✜ Delayed physeal closure This is asecondary effect of gonadectomy.

✜ Increased body weight This is frequentlyobserved in neutered animals.

In cases of spontaneous capital physeal fracture,

both hindlimbs may be affected simultaneously,

or a spontaneous fracture may develop in the

contralateral limb later on.

As with any other bonefracture, feline femoralneck fractures may besustained during a traumatic incident.Young (between 7months and 2 years ofage) male cats and non-pedigree cats are atparticular risk of beinginvolved in road trafficaccidents.10 The growthplate is a weak areathrough which fracturesmay occur in growinganimals. Interestingly,however, it has beenreported that cats under6 months of age sufferfractures of the femoralneck more frequentlythan fractures throughthe physis.11 Theauthors of that study hypothesised that growth plates in these young catscould be stronger than immature bone.

The case history generally includes a traumatic event, so a complete general physical examination is required to evaluate if the patient is stable.These cats usually present with unilateral hindlimb lameness, pain and crepi-tus on manipulation of the affected coxofemoral joint. Radiographic evalua-tion of the joint reveals a fracture through the capital physis or femoral neck,depending on the age of the cat.11

Tr a u m a t i c f r a c t u r e s

Ventrodorsal radiograph of the pelvis of a 12-month-oldcat, revealing a traumatic fracture of the neck of the femurand avulsion of the greater trochanter

It has been reported that neutering causes adelay in growth plate closure not only at thefemoral capital physis, but also in otherlocations.15,16 Other physes have indeed beenfound to remain open in cats with slippedcapital physis.7 Testosterone and oestrogenfacilitate cartilage maturation in the growthplate, so a reduction in the levels of thesehormones leads to a delay in physeal cartilagematuration and closure.15 However, the age atwhich neutering is performed does not seemto influence the degree of growth plate closure,as no difference was found between catsneutered at 7 weeks and 7 months of age.16



Open growth plates are areas susceptible to fracture. When the growth plate of cats withslipped capital physis was evaluatedhistologically, it was observed that the physiswas almost double the size of a normal growthplate, and that the chondrocytes wereirregularly distributed in clusters; necrosis wasalso present.12,13 Some authors have reportedthis pathology in the growth plates of pigs, asa form of osteochondrosis. However, the felinepresentation is different as it diffusely affectsthe entire physis and the chondrocytes lack the normal columnar distribution typical ofgrowth plates.12

Feline capital physeal fracture is similar tothe pathology suffered by obese, human maleadolescents with spontaneous slipped femoralcapital physis.

Metaphyseal osteopathyMetaphyseal osteopathy affects young, maleneutered, obese cats, and the history and clin-ical signs are similar to those associated withspontaneous capital physeal fracture.Radiographi cally severe bone lysis andremodelling are observed in the femoral neck.Pathological fractures through the capitalphysis can frequently be seen.

Histopathological evaluation of the femoralheads and necks of cats diagnosed with felinemetaphyseal osteopathy has shown focalirregularity with thickening and splitting ofthe articular cartilage. The aetiopathogenesisis not completely understood, as either anincrease or decrease in vascularisation in themetaphysis could lead to necrosis, collapseand fracture of the femoral neck (the latter sce-nario similar to Legg-Calvé-Perthes disease ofthe femoral head in dogs).17 Radiographically,loss of definition and areas of radiolucencycan be observed in the femoral neck (Fig 2).17

It is unclear whether metaphyseal osteopa-thy is a pathology in itself, or a consequence of primary fracture and subsequent boneremodelling. Queen et al17 reported 17 catswith radiographic changes consistent withmetaphyseal osteopathy. These animals pre-sented a subtle lameness that progressed to anacute worsening in the clinical signs severalweeks later. The authors discussed the possi-bility that the radiographic changes observedcould be associated with secondary boneremodelling after femoral neck fracture, avas-cular necrosis similar to Legg-Calvé-Perthesdisease in dogs, or metaphyseal osteomyelitis.However, the age of the cats (most were olderthan 1 year old) and clinical presentation

(chronic and then acute worsening, possiblydue to fracture of the bone) led them to con-clude that this was a primary disease of thefeline metaphysis giving way to a secondaryfracture of the femoral neck, rather than viceversa. In contrast to Legg-Calvé-Perthes disease in dogs, the epiphysis is not affectedin cats, which might be explained by theincreased blood supply to that area throughthe round ligament in cats, compared withdogs.

As Pérez-Aparicio and Fjeld reported in1993,11 some femoral neck fractures can healspontaneously with conservative treatment.However, they also observed that somefemoral neck fractures and all capital physealfractures did not heal and developed hyper-trophic pseudoarthrosis with time. Similarly,McNicholas et al,14 in a report of 26 cats withspontaneous capital physeal fractures unrelat-ed to trauma, observed radiographic changesin the femoral neck (osteolysis and sclerosis)secondary to the femoral fracture. The fact thatthe severity of these changes increased withincreased duration of the clinical signs, suggested to them that the femoral neck osteo -lysis and sclerosis were secondary changes.

Therefore, it remains unclear whether thechanges seen in the femoral neck are primaryor secondary in nature.


FIG 2 Ventrodorsal radiograph of the pelvisof a 2-year-old male neutered cat. There areareas of radiolucency in the proximalmetaphysis of both femurs and separationof both femoral capital epiphyses.Reproduced from Queen J, Bennett D,Carmichael S, et al, Veterinary Record, Vol 142, pp 159–62, with permission from BMJ Publishing Group Ltd

It is unclear whether metaphyseal osteopathy is a pathology in itself,

or a consequence of primary fracture and subsequent bone remodelling.

Feline capital

physeal fracture

is similar to

the pathology

suffered

by obese,

human male

adolescents

with

spontaneous

slipped femoral

capital physis.




Diagnosis

The clinician needs to include fractures of thefemoral head and neck among the differentialdiagnoses for any young feline patient withhindlimb lameness/weakness, whether or notassociated with a traumatic event. Followingcomplete ortho paedic examination to rule outother processes, such as cruciate ligament rup-ture, which are not as obvious as traumaticbone fractures, careful manipulation of the hipis necessary to determine the origin of thepain. Crepitus, pain and decreased range ofmotion can be elicited during manipulation ofthe affected hip; if there is chronicity, muscleatrophy may also be evident.

Radiographs of the pelvis and coxofemoraljoint are essential in the diagnosis of thesepathologies. A minimum of a lateral view and a ventrodorsal projection with the limbsin extension (Fig 3) should be obtained.However, sometimes the extended ventrodor-sal radiograph of the hips in cats with sponta-neous capital physeal fractures may not showany obvious abnormalities. As mentioned earlier, the collagen fibres of the joint capsulebecome tightened during extension of thelimb, which reduces the fracture and preventsits visualisation. To avoid this problem andfacilitate observation of the fracture, a frog-legged view should be taken (Fig 4).18

Positioning the patient in dorsal recumbencyand allowing the limbs to abduct freelyobtains this projection. A clear displacementof the femoral capital epiphysis can be seen insome cases; in others, only a minimal stepbetween the epiphysis and metaphysis isobserved.

Treatment approaches

While treatment of proximal femoral fracturescan potentially be achieved by conservative (seebox) as well as surgical methods, surgical treat-ment is recommended in the majority of casesto avoid the risk of non-union and dysfunction.In most cases of capital physeal fracture treatedconservatively, hypertrophic pseudoarthrosisand osteophytosis ensue, which may lead todysfunction. In cats younger than 3 months ofage with femoral neck fractures, spontaneoushealing may, however, occur.11

FIG 4 Postoperative ventrodorsal frog-legged radiographicview of the pelvis of a cat with left capital physeal fracture andavulsion of the greater trochanter. K-wires have been placed tostabilise the capital physeal fracture and a tension band (K-wiresand cerclage wire) has been used to stabilise the avulsionfracture of the greater trochanter. This projection helps tovisualise the level of penetration of the K-wires in the epiphysis

Radiographs

of the hips in a

frog-legged

position

improve

visualisation of

capital physeal

fractures that

are not

completely

clear in the

more routine

extended view.

Crepitus, pain and decreased range of motion can be

elicited during manipulation of the affected hip. If there

is chronicity, muscle atrophy may also be evident.

FIG 3 Ventrodorsal radiograph of the pelvis of an 18-month-oldcat. A capital physeal fracture is seen in the right femur (arrow)

This modality relies on natural body mechanisms to heal the fracture, so mightpotentially be appropriate for young cats with acute fractures of the femoral neckthat present with no bone lysis or remodelling. If metaphyseal osteopathy is suspect-ed radiographically, conservative treatment is unlikely to resolve the clinical signs.

Conservative treatment includes exercise restriction and analgesia. Ideally,cats should be confined to a crate or small room for at least 4 weeks, to allowhealing of the fracture. Several daily supervised walks outside the crate are recommended to prevent muscle atrophy in the affected limb. Analgesia can beprovided in the form of non-steroidal anti-inflammatory drugs (NSAIDs; eg, meloxicam) or opioid derivatives (eg, tramadol). Clinical evaluation of thepatient and radio graphs of the hip joint should be performed 4 weeks after thestart of treatment to assess patient progress and fracture healing, and deter-mine if normal activities can be progressively resumed or, conversely, whethersurgical excision of the femoral head and neck would be more beneficial.

C o n s e r v a t i v e t r e a t m e n t




Surgical stabilisation with K-wires

The objective of surgical stabilisationwith K-wires is to preserve the normalanatomy and function of the coxo -femoral joint. This prevents sideeffects associated with salvage pro -cedures: namely, muscle atrophy,decreased range of motion (especially inextension) and shortening of the limb.6However, due to the intra-articular nature ofthis type of fracture, osteoarthritis, and, there-fore, secondary chronic pain and decreasedrange of motion, could develop with time.

Reduction and stabilisation of femoral headand neck fractures can be attempted if thefracture is acute and there are no signs of boneremodelling. Surgery should be carried out assoon as possible to minimise any impact ongrowth potential and changes in the femoralneck that could compromise fracture stabilityand healing.3 This technique is not recom-mended in cats diagnosed with metaphysealosteopathy.

Technique3,18–21

It is important to aseptically prepare the entireaffected limb to allow manipulation of the legduring surgery. The limb is clipped from thedorsal midline to the tarsus, and scrubbed for5 mins with an antiseptic such as clorhexidine.Likewise, the complete limb is draped toallow intraoperative manipulation of the leg,which is essential for adequate visualisationof the fracture during surgery.

Craniolateral approach A craniolateral approach to the hip is performedwith the cat in lateral recumbency.21 The jointcapsule is incised in a T-shape andelevated from the femoral neck.Partial tenotomy of the deep glutealand vastus lateralis muscles is help-ful in exposing the femoral headand neck.

The capital physis has an L-shape that provides good stabilityfollowing reduction. However,the capitus is usually rotated inrelation to the neck and retainedin the acetabulum by the roundligament (Fig 5). Reduction of thefracture might be accomplishedby application of medial pressurefrom the femur through the frac-tured physis, while flexing andextending the hip. This will usual-ly cause the epiphysis to de-rotateand lock in place. The L-shape ofthe fractured physis will help inachieving a correct reduction and

prevent reluxation if pressure is appliedthrough it. Alternatively, the tip of asmall diameter K-wire may be used tode-rotate the epiphysis by walking italong the articular cartilage, takingcare to avoid any damage. Once thefracture has been reduced in the cor-rect position, pressure is applied from

lateral to medial. The K-wires used tostabilise the fracture can be placed in a

normograde or retrograde fashion. It ishelpful to measure the depth of the epi -

physis in preoperative radio graphs to deter-mine the distance the wires need to be drilledin, to avoid damage to the articular cartilage. ✜ Normograde placement Two or threesmall K-wires (1 or 1.2 mm diameter for cats)are drilled from the base of the thirdtrochanter, following the direction of thefemoral neck, a few millimetres into thephysis. Once the correct central position ofthe wires has been checked, the wires arewithdrawn until they are not protruding fromthe surface of the fracture. The fracture isreduced and the K-wires are carefully drilledinto the epiphysis, again ensuring they do notprotrude through the articular cartilage. Thisstep is critical to ensure adequate stabilisationof the epiphysis without interference in jointfunction. This is not always easy to judge:curved mosquito forceps can be run over thearticular cartilage to check the wires cannotbe felt, and/or the depth of the epiphysis can be determined from the radiographs.Normograde placement of pins in the femoralneck is challenging; they can alternatively bedrilled in a retrograde direction. ✜ Retrograde placement The femur isexternally rotated to visualise the fracturedsurface. The K-wires are drilled from the

fracture site into the femoral neckand lateral aspect of the thirdtrochanter. The drill is thenattached to the opposite end of the wire, which is partiallywithdrawn until the initial endcannot be seen protruding fromthe physeal surface. The fractureis reduced into position, and the K-wires are drilled into thefemoral head epiphysis, asdescribed above. If the K-wire tobe used does not have a trocarpoint on each end, thenarthrodesis wires of adequate sizecould be used instead. Althoughthis technique allows moreaccurate positioning of the K-wires in the femoral head, the drilling process might bechallenging, as the femur needs tobe substantially externally rotated.

FIG 5 Intraoperative view of a capital physeal fracture(arrow), with separation ofthe epiphysis from themetaphysis. Courtesy of Dr Silke Stein

DECISION-MAKING:Surgical stabilisation

Open reduction and stabilisation of a capitalphyseal fracture with K-wires needs to beundertaken as soon as possible (in the first 3–4days) to minimise alterations in vascularisation ofthe epiphysis and remodelling of the metaphysis.Chronic fractures, in which bone remodelling

can already be visualised radiographically orintraoperatively, are best managed with

femoral head and neck excision.




It has been reported that parallel K-wiresare biomechanically superior to divergentwires,22 so an effort must be made to place thepins parallel to each other and to the femoralneck. Specially designed drilling guides toallow parallel drilling are available (Fig 6).

Once the fracture has been reduced and stabilised, the joint is manipulated to checkstability and any potential impingement of theimplants. The joint capsule is closed withabsorbable suture (eg, 3/0 PDS [polydiox-anone]) in a cruciate pattern. The tenotomisedmuscles are repaired with absorbable suture(eg, 3/0 PDS) in a cruciate or mattress pattern.Closure of the rest of the soft tissues is routine.

Ventromedial approachA ventromedial approach to the hip and sta-bilisation with two K-wires has also beendescribed.23 This approach requires dissectionbetween the iliopsoas and adductor longusmuscles and subtotal pectinectomy. Once thefracture has been reduced by distal distractionof the femur site, the K-wires are placed fromthe articular cartilage through the physis intothe femoral neck.

A ventral approach to the hip permits bettervisualisation of the articular surface of the epi-physis, due to the presence of a ventral notchthat interrupts the acetabular rim. A K-wire isplaced in the fovea capitis femoris and drilledtowards the third trochanter. A second K-wireis inserted cranial to the first one and directedcaudally to cross the first wire. The K-wiresare retracted, cut short and countersunkbelow the level of the articular cartilage,which is essential to preserve joint function.According to the authors who described thisapproach, its advantages are that it minimisessoft tissue and vascular damage, and allowsdirect visualisation of the fracture.23 However,the ventral approach to the coxofemoral jointis not frequently used and it can be challeng-ing for a surgeon unfamiliar with it.

Irrespective of the surgical approach, radio -graphs should be taken postoperatively toassess adequate placement of the K-wires and penetration of the epiphysis without protrusion into the joint. A frog-legged view is best for evaluating this (Fig 4). If sub optimal placement of the K-wires is suspected (intra-articular, not deepenough in the epi physis, protrudingfrom the femoral neck, etc), additionalviews, including fluoroscopy, can beperformed to try to determine the exactposition of the implants and decidewhether further action is needed. If onlyone wire is adequately engaging the epi-physis, for example, a second wire shouldbe inserted to prevent rotation and instabil-ity of the fragment.

Postoperative careThe patient should be kept hospitalised withinjectable analgesia to cover the first 24–48 hpostoperatively. Opioids (buprenorphine: 0.03mg/kg IV q6–8h) and NSAIDs (meloxicam:0.2 mg/kg SC first dose, then 0.05 mg/kg POq24h) make a good analgesic combination.Once the patient is discharged, the low dose ofmeloxicam can be administered at home for 4 days.

Physiotherapy is important during the post-operative period if the cat tolerates it. Coldpacks applied over the operated hip for thefirst 48 h after surgery help reduce inflamma-tion and pain. After this period, the owner canapply warm packs and perform gentle passiverange of motion exercises several times dailyuntil the cat is consistently using the operatedlimb. Bandages, such as Ehmer or 90 degreebandages, are not well tolerated by cats; fur-thermore, they would not allow physiotherapy,which is essential to recover joint range ofmotion and muscle volume. They are not need-ed if adequate exercise restriction is instituted.

The patient’s activity level is restricted for4–6 weeks postoperatively, either by confiningthe cat to a big crate or to a small room fromwhich any furniture the cat might be temptedto jump onto/from has been removed. Ifusing a crate, several short daily supervisedwalks outside the crate are recommended toprevent muscle atrophy of the operated limb.The activity level can be progressivelyincreased, provided the cat is progressing ade-quately and the recheck radiographs (usuallytaken 4 weeks after surgery) show good bonehealing and stable implants.

Femoral head and neck excision

Femoral head and neck excision allows the formation of a pseudoarthrosis (fibrous falsejoint) in the hip. By avoiding bony contactbetween the femur and the pelvis, pain is eliminated. However, limb shortening and adecreased range of motion is to be expected, sosome degree of gait abnormality may persistafter this surgery.3,20 Mild muscle atrophy isalso to be expected, especially in chronic cases.

Femoral head and neck excision is a salvageprocedure and irreversible – ideally, the

joint should be preserved if at all possible.

Technique3,20,21

Aseptically prepare the entire affectedlimb, as it will need to be manipulatedduring surgery to enable an adequateostectomy in the femoral neck. A cranio-

lateral approach to the hip is performedwith the cat in lateral recumbency.

The joint capsule is incised in a T-shape andelevated from the femoral neck. Partial

DECISION-MAKINGFemoral head and neck excision

Although performing a salvage procedure ofthe femoral head and neck (femoral head andneck excision) is a quick and easy approach,which usually leads to adequate limb func-tion in the patient, preserving the coxo -

femoral joint should be attemptedwhen no bone lysis/remodelling

is seen.

FIG 6 Drillguide thatfacilitatesparallelplacementof K-wiresfrom thebase of the thirdtrochanterinto theepiphysis ofthe femoral head




tenotomies of the deep gluteal andvastus lateralis muscles are helpfulin exposing the femoral neck. Aperiosteal elevator may be used tohelp elevate the vastus lateralis muscle from the neck of the femur.Placement of a Gelpi retractor great-ly improves visualisation of the joint.

The round ligament is cut and thefemoral epiphysis removed withforceps. The landmarks to performan adequate ostectomy in thefemoral neck are the medial aspectof the greater trochanter laterally,and the lesser trochanter medially(Fig 7). In cats, the lesser trochantermay be difficult to palpate duringsurgery given its small size, but hav-ing radiographs of the extendedpelvis to hand might be helpful indetermining the approximate loca-tion of this structure. Complete removal of thelesser trochanter should be avoided wheneverpossible, as it is the insertion of the iliopsoasmuscle, an important flexor of the hip.

In a transverse plane, the ostectomy shouldnot be performed perpendicularly to thefemoral neck, as this would create a spike in thecaudal aspect of the femur that could be a causeof discomfort for the patient. Rather, the limb isexternally rotated so that the patella is orientedtowards the ceiling and the cut is performedperpendicularly to the operating table. It is use-ful to mark the cutting line in the bone with elec-trocautery, between the landmarks describedabove, to help guide the ostectomy (Fig 8).

Once the ostectomy has been performed andthe head and neck of the femur removed, it isimportant to check for any irregularities in thesurface of the cut and eliminate them withrongeurs or files. The limb is then moved intoa normal position and the joint manipulated tocheck for any impingement or rubbing of boneon bone. Although this manipulation shouldbe in all directions, flexion and extension arethe normal movements during walking, andlack of impingement in this plane is the mostrelevant for a successful outcome.

The joint is lavaged prior to closure in orderto remove debris. Closure of the joint capsuleis important to add stability to the false jointjust created. Absorbable suture (3/0 PDS) isused in a simple interrupted or cruciate pat-tern. The tenotomised muscles are repairedwith absorbable suture (3/0 PDS) in a cruciateor mattress pattern. The rest of the soft tissuesare closed in a routine manner.

Radiographs should be taken postopera-tively to ensure an adequate ostectomy, withcomplete removal of the femoral head andneck. Positioning the hip in extension allowsbetter evaluation of the cut (Fig 7).

Postoperative careAnalgesia, especially for the first 48 h after surgery, is essential toencourage early use of the operatedlimb. The same analgesic protocol asdescribed for surgical stabilisation ofa physeal fracture can be used (opioids and NSAIDs). Once thepatient is discharged, the low doseof meloxicam can be administered athome for 4 days.

Physiotherapy is important dur-ing the postoperative period if thecat tolerates it. Cold packs appliedover the operated hip for the first 48 h after surgery help reduceinflammation and pain. After thisperiod, the owner can apply warmpacks and perform gentle passiverange of motion exercises severaltimes a day until the cat is consis-

tently using the operated limb. Bandagesshould not be applied after this type of sur-gery. Exercise is controlled by restricting thecat to a small room for 2 weeks; thereafter progressive access to the rest of the house isallowed to encourage use of the operated limband improve joint range of motion.

Early detection of pain is essential to pre-vent a vicious cycle leading to limb disuse andmuscle atrophy.

FIG 7 Postoperativeventrodorsal radiograph ofthe pelvis after femoral headand neck excision. Theostectomy is performedbetween the medial aspectof the greater trochanter(white arrowhead) and lessertrochanter (black arrow),without removing eithertrochanter

The limb is

externally

rotated so that

the patella

is oriented

towards the

ceiling and

the cut is

performed

perpendicularly

to the operating

table. It is

useful to mark

the cutting line

in the bone with

electrocautery.

FIG 8 Intraoperative view showing the line of an ostectomy.The limb is externally rotated 90º to make the cut. The patella(circled) should be pointing at the ceiling and the ostectomyperformed between the medial aspect of the greater andlesser trochanters (dashed line). No irregularities or spikesshould be felt on the surface of the cut




operated joint. Depending on the degree ofdegenerative changes, patients may showclinical signs secondary to this pathology laterin life.

A good to excellent outcome has beenreported in most studies of cats after femoral

FIG 9 Ventrodorsal radiograph of the pelvis in a cat that hadpreviously undergone incomplete excision of the femoral headand neck. Orthopaedic examination revealed pain, crepitusand severe muscle atrophy. The recommended line of theostectomy is revealed by the dashes

Outcome

Cats undergoing open reduction and stabilisa-tion of femoral head and neck fractures withK-wires have a good to excellent progno-sis.3,18–20,25 Surgery preserves the anatomy andfunction of the coxofemoral hip, avoidingcomplications derived from more aggressivetechniques. However, on occasion, an ‘applecore’ appearance of the femoral neck isobserved radio graphically during postopera-tive rechecks. This is an indication of changesin vascularisation and osseous remodelling.Removal of the implants when the fracturehas healed resolves these changes.3,25 As capital physeal fractures are intra-articularfractures, osteoarthritis may develop in the

It has been

reported that

animals having

clinical signs

for longer than

6 months

before surgery

have a poorer

outcome.

Total hip replacement (THR) is widely performed in large-breed dogs with end-stagecoxofemoral osteoarthritis that is non-responsive to medical treatment. It has alsobeen described as a treatment for cats with capital physeal fractures, as a micro-THR system has been developed for use in small dogs and cats.24 The recovery ofthe cats included in this report after THR was excellent, based on clinicalparameters such as muscle mass, coxofemoral range of motion, gait and theowner’s subjective assessment. The surgery, however, is technically demanding,requires advanced training and considerable financial investment. A description ofthe technique can be found in the above-mentioned report.24

To t a l h i p r e p l a c e m e n t

An 8-month-old female cat suffered a fall indoors 7 days prior to presentation and had since beenlame on her left hindlimb. Crepitus and pain wereelicited on manipulation of the left hip. Radiographsof the pelvis were taken under anaesthesia (a).

✜ WHAT IS YOUR RADIOGRAPHIC DIAGNOSIS? ✜ WHAT TREATMENT SHOULD BE PERFORMED

IN THIS CASE, AND WHY?✜ WHAT POSTOPERATIVE MANAGEMENT PROTOCOL

WOULD YOU RECOMMEND?

C a s e n o t e s

There is a fracture in the neck of the left femur (radiograph a).Radiolucency, remodelling and narrowing of the left femoral neck can also be observed. (These changes are suggestive of underlying metaphyseal osteopathy or bone remodellingsecondary to the neck fracture.) Muscle atrophy of the left hindlimb is visible.

Given the chronicity of the fracture (7 days) and the radiographic changes alreadyvisible in the femoral neck, femoral head and neck excision is the recommended treatment. Theosseous changes seen radiographically could compromise an attempt to reduce and stabilise thisfracture with K-wires. Radiograph (b) shows the pelvis after femoral head and neck excision.

Postoperative analgesia is essential to encourage early use of theoperated limb. Controlled exercise for 2 weeks, and then a progressive increase in exercise levelwith encouragement to use the operated limb, is recommended. Physiotherapy, including cold

packs for the first 48 h and then warm packs and passiverange of motion exercises, will help to maintain a goodrange of motion in the hip.

MULTIMEDIA Two video recordings of the cat,

one at presentation and one post-surgery,are included in the online version

of this article atdoi:10.1016/j.jfms.2011.05.007

a

b



✜ Young, male neutered, obese cats are predisposed to sufferingfrom spontaneous capital physeal fractures and metaphysealosteopathy.

✜ Early detection and diagnosis of capital physeal fractures allowstabilisation of the slipped capitis with K-wires.

✜ Stabilisation with parallel K-wires is biomechanically superior toplacement of divergent K-wires.

✜ For chronic fractures and metaphyseal osteopathy, femoral head and neck excision is recommended, as changes invascularisation and remodelling of the femoral neck maycompromise surgical stabilisation.

✜ Adequate anatomical landmarks and surgical technique are essential for a successful outcome after femoral head and neck excision.

KEY POINTShead and neck excision.26 However, mild lame-ness, shortening of the limb, decreased rangeof motion or pain on manipulation of the hipoccur in some cases. An unsatisfactory out-come is usually due to incomplete removal ofthe femoral neck, which causes painful rub-bing against the acetabulum (Fig 9). It has beenreported that the duration of clinical signsbefore surgery influences outcome, with animals exhibiting clinical signs for longerthan 6 months having a poorer outcome.27

male and female domestic cats. Vet Radiol Ultrasound 1997; 38:42–47.

17 Queen J, Bennett D, Carmichael S, et al. Femoral neck meta-physeal osteopathy in the cat. Vet Rec 1998; 142: 159–62.

18 Fischer HR, Norton J, Kobluk CN, et al. Surgical reductionand stabilization for repair of femoral capital physeal frac-tures in cats: 13 cases (1998–2002). J Am Vet Med Assoc 2004; 224:1478–82.

19 Culvenor JA, Black AP, Lorkin KF, et al. Repair of femoral capital physeal injuries in cats – 14 cases. Vet Comp OrthopTraumatol 1996; 9: 182–85.

20 Piermattei DL, Flo GL, DeCamp CE. Handbook of small ani-mal orthopedics and fracture repair. 4th edn. Philadelphia,Pennsylvania: Saunders Elsevier, 2004.

21 Piermattei DL, Johnson KA. An atlas of surgical approaches tothe bones and joints of the dog and cat. 4th edn. St Louis:Saunders Elsevier, 2006.

22 Lambrechts NE, Verstraete FJM, Sumner-Smith G, et al.Internal fixation of femoral neck fractures in the dog – an invitro study. Vet Comp Orthop Traumatol 1993; 6: 188–93.

23 Guerrero TG, Koch D, Montavon PM. Fixation of a proximalfemoral physeal fracture in a dog using a ventral approachand two Kirschner wires. Vet Comp Orthop Traumatol 2005; 18:110–13.

24 Liska WD, Doyle N, Marcellin-Little DJ, et al. Total hipreplacement in three cats: surgical technique, short term out-come and comparison to femoral head ostectomy. Vet CompOrthop Traumatol 2009, 22: 505–10.

25 Voss K, Langley-Hobbs SJ, Montavon PM. Hip joint. In: Montavon PM, Voss K, Langley-Hobbs SJ, eds. Felineorthopaedic surgery and musculoskeletal disease.Philadelphia, Elsevier Science, 2009: 443–54.

26 Berzon JL, Howard PE, Covell SJ, Trotter EJ, Dueland R. A retrospective study of the efficacy of femoral head and neckexcisions in 94 dogs and cats. Vet Surg 1980; 9: 88–92.

27 Gendreau C, Cawley AJ. Excision of the femoral head andneck: the long-term results of 35 operations. J Am Anim HospAssoc 1977; 13: 605–8.

Available online at www.sciencedirect.com

Acknowledgements

The author would liketo thank Dr Silke Steinfor providing some ofthe images.

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Young, male neutered, obese, lame?: Non-traumatic fractures of … · observed in neutered animals. In cases of spontaneous capital physeal fracture, both hindlimbs may be affected

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