Meniscal damage diagnosed by ultrasonography in horses: A retrospective study of 74 femorotibial...

ORIGINAL RESEARCH

Volume 26, Number 10 453

ABSTRACT

This retrospective study reports diagnostic findings in 74horses with ultrasonographic diagnosis of femorotibialjoint damage; it describes the ultrasonographic featuresof meniscal tears and determines the prevalence of me-dial or lateral meniscal involvement and of associatedsynovial effusions. Horses were classified into fourgroups: with medial meniscal damage, with lateralmeniscal damage, with lesions in both menisci, and withno ultrasonographic evidence of meniscal damage. Afterultrasonographic appearance, meniscal lesions were de-scribed as central degeneration, horizontal tear, partialoblique tear of the distal angle, combined horizontal andoblique tears, or complex tear. Meniscal protrusion orother associated ultrasonographic or radiographic abnor-malities were recorded. Of the 74 horses, 54 (73%) hadmedial meniscal damage, 5 (6.75%) had lateral meniscaldamage, 5 (6.75%) had lesions in both menisci, and 10(13.5%) had no meniscal lesion. Meniscal protrusion oc-curred in 20 cases (27%). Horizontal tears were the mostfrequent type of meniscal lesion (26 horses). Complex le-sions were found in 6 lateral menisci and 14 medialmenisci. Lesions of the cranial meniscal ligaments wereseen in 10 horses. Synovial effusion of one or severaljoint compartments was found in 51 cases (68.9%).

This study demonstrates the high prevalence ofmeniscal tears and synovitis in horses with ultrasono-graphic evidence of femorotibial derangement. Basedon this series of clinical cases, horizontal tears of themedial meniscus appear to be the most frequent softtissue injury of the equine stifle.

Keywords: Horse; Ultrasonography; Stifle; Meniscus;Meniscal tear

From the Medical Imaging Section, Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Liège, Belgium.Reprint requests: Virginie De Busscher, DVM, Medical Imaging Section,Department of Clinical Sciences, Faculty of Veterinary Medicine, University ofLiège, Boulevard de Colonster, 20, Bât. B41, Sart-Tilman, 4000 Liège, Belgium.0737-0806/$ - see front matter© 2006 Elsevier Inc. All rights reserved.doi:10.1016/j.jevs.2006.08.003

Meniscal Damage Diagnosed by Ultrasonography inHorses: A Retrospective Study of 74 FemorotibialJoint Ultrasonographic Examinations (2000-2005) Virginie De Busscher, DVM, Denis Verwilghen, DVM, Géraldine Bolen, DVM,Didier Serteyn, DVM, PhD, dipECVA, and Valeria Busoni, DVM, PhD, dipECVDI

INTRODUCTIONLittle published information is available on soft tissueinjuries of the equine stifle, their diagnosis, and associ-ated clinical signs.1-10 Literature describes and classifiesmeniscal lesions in detail using magnetic resonanceimaging (MRI) in human medicine.11-18 However, theuse of MRI in live horses to assess the menisci has notbeen described.19,20 Ultrasonography is routinely usedto assess soft tissue structures and bony surfaces of thelimbs and has been used to image the menisci in bothhumans21 and horses.1-3,5,7-10 The procedure for ultra-sonographic evaluation of the equine stifle and normalultrasonographic anatomy of the joint have been de-scribed by several authors.2,4,6,8,22-26 Denoix and col-leagues have reported the ultrasonographic appearanceof meniscal injuries.1-5,7,8,10 A retrospective study onequine meniscal injuries diagnosed at ultrasonographyhas proved that lameness, prominent stifle effusion,and uniaxial degenerative joint disease are often associ-ated with meniscal damage.9 Diagnostic arthroscopyhas been used to assess meniscal damage and cranialmeniscal ligament tears,27-32 and it is routinely used totreat meniscal tears in the cranial aspect of the joint.33

At ultrasonography, meniscal tears have been describedas hypoechoic. Hypoechoic defects have been inter-preted as fiber disruption or collapse, edema, fibropla-sia, or necrosis.3,5,8 Hyperechoic images also have beendescribed in the equine menisci and reported as bonemetaplasia.2,3 However, no detailed description of theultrasonographic features of meniscal abnormalities isavailable.

The aims of this retrospective study were to reportclinical presentation and diagnostic findings in horseswith ultrasonographic diagnosis of femorotibial jointdamage, describe the ultrasonographic features of menis-cal tears in the horse, determine the prevalence of medialor lateral meniscal involvement and the type of tear in aseries of clinical cases, establish the prevalence of associ-ated synovitis and degenerative joint disease, and relatethe outcome of the horses with femorotibial damagebased on ultrasonographic findings.

REFEREED

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454 Journal of Equine Veterinary Science October 2006

MATERIALS AND METHODS

Case Selection

Clinical cases admitted to the Imaging Section of theFaculty of Veterinary Medicine of Liège from January 2000to April 2005 were retrospectively reviewed, and horsesthat had undergone an ultrasonographic examination ofthe stifle region were selected. Horses that had abnormalultrasonographic findings in one or both femorotibialjoints were retained for this study. Cases in which the ultra-sonography was normal or with abnormalities not concern-ing the femorotibial joints were excluded. A case record of74 horses with ultrasonographic abnormalities was re-viewed among 130 stifle ultrasonographic examinations.

Diagnostic FindingsThe results of the clinical examination, including degree oflameness (5 grades, AAEP guidelines), evidence of jointeffusion, and positivity of flexion tests, were reviewed foreach case. Lameness was classified as recent or old if it hadoccurred for less than or more than 3 months, respectively.

The radiographs (Philips M50 machine with a supero-talix tube) and the ultrasonographic images (Aloka SSD*3500, 7.5 MHz linear transducer; Aloka Prosound SSD-3500, Mechelen, Belgium) were retrospectively reviewed.

On the basis of the meniscal damage detected by ultra-sonography, horses were classified into four groups:horses with medial meniscal damage (group 1), horseswith lateral meniscal damage (group 2), horses with le-sions in both menisci (group 3), and horses with no ultra-sonographic evidence of meniscal damage (group 4).After their ultrasonographic appearance, meniscal lesionswere described and classified into five types. Central hy-poechogenic areas with irregular margins were inter-preted as central degeneration and classified as type 1.Linear hypoechoic images with straight margins were ar-bitrarily defined as tears. Indeed, the nature of the hypo-echoic regions was not defined. Tears were classified ashorizontal when the tear divided the meniscus into prox-imal and distal portion and the hypoechoic band was par-allel to the tibial plateau (type 2). Tears were classified asoblique when the tear was intermediate between horizon-tal and vertical and the hypoechoic band ran from the dis-tal surface of the meniscus toward the outer surface of themeniscus (type 3). The combination of a horizontal tearand an oblique tear was classified as a type 4 lesion. Whenthe meniscus was severely affected and appeared separatedin parts by several hypoechoic bands oriented in differentdirections, the lesion was classified as a complex tear (type5). Meniscal protrusion or meniscal fragment displace-ments were evaluated in combination of each type of tear.

The presence of other associated soft-tissue abnormali-ties such as joint effusion, synovial membrane prolifera-tion, hyperechoic debris floating in the synovial fluid,damage of the cranial meniscal ligaments and degenera-

tive joint disease were assessed for each case. The differ-ent combinations of synovial effusions [medial femorotib-ial (MFT) recess, lateral femorotibial (LFT) recess,femoropatellar (FP) recess, and cranial femorotibial (cFT)effusion] were considered.

Radiographic abnormalities such as subchondral bonecysts, osteochondrosis, arthritis, or degenerative joint dis-ease were reported.

The probability of having MFT or LFT effusion in oneof the groups (1, 2, 3, or 4) was statistically tested usinga Fisher’s exact test. Differences were considered signifi-cant at P � .05. The correlation between type of tear andgrade of lameness, between cranial meniscal ligament le-sion and the type of meniscal lesion, and between pres-ence of cFT effusion and the type of meniscal lesion wasalso tested (Fisher’s exact test, P � .05).

OutcomeThe general outcome, persistence of the lameness, andlevel of work were assessed by telephone follow-up withthe owner. Three grades were established. The outcomeswere categorized as good (horse returned to full athleticfunction), moderate (light work only or breeding), orpoor (still lame and pensioned, sold, or humanely de-stroyed because of persistent lameness). When the horsewas sold for unknown reasons, it was not included in theoutcome study. The correlation between the type ofmeniscal tear and the outcome was studied (Fisher’s exacttest, P � .05).

RESULTS

Horses and Clinical Results

Seventy-four horses with ultrasonographic abnormalitiesof 74 stifles were reviewed among 130 stifle ultrasono-graphic examinations performed between January 2000and April 2005. The selected group included 30 mares,32 geldings, and 12 stallions, aged 6 months to 20 years(mean, 9 years). Twenty-four different breeds were repre-sented; 43 of 74 horses were warmblood.

All horses were lame (grades 1 to 4/5, mean 3/5). Thegrade 3/5 concerned 29 of 74 horses. No statistical cor-relation was found between the type of meniscal tear andthe grade of lameness. Detailed clinical data were availablefor 53 of 74 cases. Thirty-nine of 53 horses had synovialpalpable effusion that were reported as mild (n � 22),moderate (n � 10), or severe (n � 7). Forty-eight of 53horses had a positive flexion test of the affected hindlimb:37 had a mild response, 10 had a moderate response, and1 had a severe response. A selective flexion test was notperformed on these clinical cases.

Meniscal DamageOf the 74 horses selected, 54 had medial meniscal damage(group 1), 5 had lateral meniscal damage (group 2), 5 had



lesions in both menisci (group 3), and 10 had no meniscallesion (group 4). The assignment of the horses to the fourgroups and the proportion of the different types of menis-cal damage are reported in Fig. 1 and Fig. 2. Protrusion ofthe meniscus occurred in 20 horses. Fifteen horses with aprotruded meniscus were in group 1, one was in group 2and 4 [3 lateral menisci (LM) and 1 medial meniscus(MM)] were in group 3 (Table 1). Two MM of group 1were prolapsed without other meniscal lesion (2.9% of the69 damaged menisci, Fig. 2).

Type 1 lesions were found in 1 LM and in 15 MM(23.2% of the 69 damaged menisci, Fig. 3) and in 7horses without any synovial effusion.

Horizontal tears (type 2, Fig. 4) were the most fre-quent type of meniscal lesions found in 26 horses(37.65%). Twenty-four of 26 horizontal tears were foundin the MM. Horizontal tears alone were found in 27.5%of the 69 damaged menisci. Seven horizontal tears in theMM were associated with an oblique tear of the distalangle (10.15% of the 69 damaged menisci, type 4, Fig. 5).

Oblique tears alone (type 3) were found in four horsesof group 1 and in one horse of group 3 (7.25% of the 69damaged menisci, Fig. 6). The oblique tear was partial andinvolved the medial angle in four MM whereas it was com-plete and involved the entire meniscal body in one LM.

Complex lesions (type 5) were seen in 20 horses (29%of the 69 damaged menisci, Fig. 7). Six of the 20 complextears involved the LM; 14 involved the MM. In the MM,the complex tears mainly involved the distal half of themeniscus when the meniscus was not prolapsed (fivehorses). Eight complex lesions of the MM were associatedwith meniscal prolapse.

Hyperechoic areas with acoustic shadowing were foundin two MM of group 1 and in one LM of group 3 andwere interpreted as calcifications.

Associated Ultrasonographic AbnormalitiesFifty-one of the 74 horses (68.9%) had synovial effusion ofone or several compartments. Seven horses had prolifera-tion of the synovial membrane in the medial recess of theMFT joint without effusion. Thirty-nine horses in group 1,5 horses in group 2, 4 horses in group 3, and 10 horses ingroup 4 had some degree of synovitis (Table 1). Six horsesin group 1 and one horse in group 4 had only proliferationof the synovial membrane of the MFT recess. The synovialeffusion was most frequently found in the MFT recess (Fig.8). MFT effusion was found in 32 horses in group 1, 1horse in group 3 and 7 horses in group 4. Fisher’s exact testshowed a positive correlation between the presence of anMFT effusion and a medial meniscal lesion in group 1. Thiseffusion was 5.8 times more frequent in group 1. The fivehorses with lateral meniscal lesions presented four LFT ef-fusions (Fig. 9) and four cFT effusions (Fig. 10). Fisher’sexact test showed that an LFT effusion was 5.3 times morefrequent in the other group than group 1. Four of the 10effusions found in horses without ultrasonographic evi-dence of meniscal lesion (group 4) concerned the threesynovial cavities (MFT, LFT, and FP recesses). One ofthese four horses had cFT effusion in addition to the oth-ers. The six other horses with synovial effusion without vis-ible meniscal damage had one or two recesses affected.

In 15 of the 40 horses with synovial effusion of theMFT recess (37.5%), hyperechoic dots without acousticshadowing were seen in suspension in the synovial fluid.

Figure 1. Proportion of meniscal injuries (MM � me-dial meniscus / LM � lateral meniscus)

Figure 2. Proportion of type of tears (MM � medialmeniscus / LM � lateral meniscus)

13.50%10 NORMAL

6.75%5 LM TEARS

6.75%5 MM AND LM 73%

54 MM TEARS

Prolapse2 MM

20 Complex tears14 MM

6 LM

5 Oblique tears4 MM1 LM

16 Centralheterogenous

tears15 MM

1 LM

19 Horizontal tears

17 MM2 LM

+ 7 Horizontal &oblique tears

7 MM



The cFT recess was distended in seven horses of group1, in four horses of group 2, in three horses of group 3,and in three horses of group 4.

Lesions of the cranial meniscal ligaments were observedin eight horses in group 1 and two horses in group 3(Table 1). The bone surface was altered, the ligament hada heterogenous aspect, and there was an associated local

effusion of the cFT recess in 3 of 10 cases (one case ingroup 1 and two cases in group 3).

Three horses in group 1, one horse in group 3, and onehorse in group 4 had medial collateral desmitis (Table 1).

Forty-four horses (59.5%) had ultrasonographic signsof degenerative joint disease (34 in group 1, three ingroup 2, two in group 3, and five in group 4; Table 1).

Figure 3. Longitudinal ultrasonographic image of themedial meniscus: hypoechogenic heterogenous centralarea (central degeneration), lesion of type 1.

Figure 4. Longitudinal ultrasonographic image of themedial meniscus: horizontal tear, lesion of type 2.

Figure 5. Longitudinal ultrasonographic image of themedial meniscus: combined horizontal and obliquetears in the same meniscus, lesion of type 4.

Figure 6. Longitudinal ultrasonographic image of themedial meniscus: partial oblique tear of the distalangle, lesion of type 3.

453-461_YJEVS558_Bussch_CP 10/6/06 1:10 PM 56


Radiographic Abnormalities

Thirty-six horses (48.6%) had radiographic signs of de-generative joint disease (28 in group 1, three in group 2,one in group 3, and four in group 4; Table 1).

Four horses in group 1 had a subchondral bone cyst; onehorse in group 1 and one horse in group 4 had radio-graphic evidence of osteochondrosis of the lateral trochlearridge of the femur, and one horse in group 2 had radio-graphic signs of sequels of an old septic arthritis (Table 1).

Figure 10. Longitudinal ultrasonographic image ob-tained at the cranial aspect of the flexed stifle: synovialeffusion of the cranial femorotibial recess.

Figure 9. Longitudinal ultrasonographic image ob-tained at the lateral aspect of the lateral femorotibialjoint: synovial effusion and proliferation of the syn-ovial membrane.

Figure 7. Longitudinal ultrasonographic image of thelateral meniscus: complex tear of the cranial horn, le-sion of type 5.

Figure 8. Longitudinal ultrasonographic image ob-tained at the medial aspect of the medial femorotibialjoint: synovial effusion and hyperechoic dots in sus-pension without acoustic shadowing.



OutcomeFollow-up information was obtained for 28 horses ingroup 1, 4 horses in group 2, 2 horses in group 3, and 3horses in group 4.

In group 1, six horses (1 Friesian, 1 pony, 2 SellesFrançais, 1 Westphalian, and 1 other warmblood) had agood outcome, nine (1 Anglo-Arabian, 1 DutchWarmblood, 1 Lusitano, 1 pony, 1 Selle Français, and 4other warmbloods) had a moderate outcome, 8 (1 Anglo-Arabian, 1 Belgian warmblood, 1 pony, 1 Quarter Horse,1 Selle Français, 1 Tinker, and 2 other warmbloods) hada poor outcome, 4 (1 Oldenburg, 1 Selle Français, 1 trot-ter, and 1 warmblood) were sold, and 1 Dutch warm-blood was euthanized for unknown reason. The fourhorses in group 2 (1 Quarter Horse, 1 Trakehner, and 2warmbloods) and the two horses in group 3 (1 draft horseand 1 warmblood) had a poor outcome. One warmbloodhorse in group 4 had a moderate outcome, and the twoothers (1 Dutch warmblood and 1 Rheinland) had a pooroutcome. Six horses with complex lesions had a poor out-come, and two had a moderate outcome. No statisticalcorrelation between type of meniscal damage and out-come was found.

DISCUSSION As in the study of Walmsley and colleagues,30 analysis of theclinical signs did not help to predict the type of injury in thestifle because there were no clinical signs common to all thecases or to one group. The proportion of horses with pos-itive flexion tests in this retrospective study (48 of the 53horses with detailed clinical data, 90%) is higher than thosepreviously reported. Walmsley and colleagues had 45 posi-tive flexion tests among 76 horses (59%), and Flynn andWhitcomb had six positive flexion tests in 14 horses withmeniscal lesions.9,30 The onset, degree, or duration oflameness was not correlated with the type of meniscal tear,nor did it appear to be correlated to the outcome. This maybe related to the intrinsic limitations of a retrospectivestudy: lack of detailed clinical data for some horses andlameness evaluated by different clinicians. In any case, theevaluation of the clinical signs was beyond the aims of thisretrospective study. Indeed, only a few intra-articular anes-thesias have been realized and, as in a retrospective study,no comparison with a control group of numerous soundhorses of the same category of age has been done.

The results of the current study confirm the value of ul-trasonography in the diagnosis of meniscal damage in the

Total Meniscal Synovitis Prolapse Cranial Medial DJD DJD Cyst OtherLesions + Without of Meniscal Collateral (US) (X-rays) Radio-Synovitis Meniscal Meniscus Ligaments 1 Desmitis graphic(Effusion or Lesion Lesions FindingsProliferativeMembraneWithoutEffusion)

Group 1:MM 54 39 — 15 8 3 34 28 4 1 OC

Group 2:LM 5 5 — 1 — — 3 3 — 1with

sequels ofasepticarthritis

Group 3:LM �MM 5 4 — 4 2 1 2 1 — —

Group 4:Nomeniscallesion 10 — 10 — — 1 5 4 — 1 OC

Abbreviations: MM, medial meniscus; LM, lateral meniscus; DJD, degenerative joint disease; US, ultrasonography; OC, osteochondrosis of thelateral trochlear ridge of the femur.

Table 1. Ultrasonographic findings correlated to meniscal lesions of 74 horses



horse. The occurrence of meniscal damage in this studywas higher than in previous reports.3,9 This high occur-rence (64 horses with meniscal lesions of 74) can be ex-plained by the criteria of selection of the study, which ex-cluded normal ultrasonographic examinations andabnormal ultrasonographic examinations where thefemorotibial joints were not involved. Moreover, the totalnumber of menisci with tears could have been underesti-mated in previous reports because of the quality of theimages obtained with older ultrasound machines or be-cause tears could be totally unapparent when pressureover the meniscus collapses the tear.2 The present studymay overestimate meniscal damage. In fact, hypoechoicimages in the meniscus can be seen in sound horses(Busoni V, personal communication) or can be created byan inadequate position of the probe or of the limb.

As in previous studies, the MM was affected more fre-quently than the LM.1,3,9,30 Fifty-nine MM and 10 LMlesions were detected. These percentages of 85.5% MMversus 14.5% LM are comparable to those of previousstudies, which reported 80% of affected MM versus 20%LM mainly encountered in young animals.7,10 The higherprevalence of medial meniscal damage may be explainedby the lower mobility and higher weight-bearing of theMM compared with the LM, which is therefore less sus-ceptible to compression and dilacerations.34

The description of tears used for this study is the sameas that used in the human literature.15 Previous veterinaryreports do not describe morphology of meniscal tears andtherefore a comparison of our results to other studies isnot possible.9,29,30

The meniscal lesions more frequently encountered werehorizontal tears followed by type 1 lesions in the MM.Abnormal anechoic or hypoechoic images could representtears in the menisci, fiber disorganization, edema, or fibro-plasias.3,5 Accumulation of fluid in a recent lesion or agranulation tissue in an older lesion or a degenerative zonecould give the same images as well.8 All linear hypoechoicimages in menisci of the current study were arbitrarily de-fined as tears. However no postmortem gross or histologicexamination of menisci of the horses were included in thisstudy. A previous study of Denoix and colleagues reportedmore edema or fibroplasias, described as large and very hy-poechogenic areas in the deep (axial) and distal parts ofmenisci than horizontal tears.3 Flynn and Whitcomb9 ex-amined 3 out of 14 horses with damaged menisci atnecropsy and confirmed meniscal injury demonstrated byultrasonography, but no detailed pathological descriptionof the meniscal lesions was available.

Type 1 lesions were more common in the MM than inthe LM and in 7 of the 15 MM it was not associated withsynovial effusion. Type 1 lesions were defined as centraldegeneration and were based on an ongoing study on ul-trasonographic and histologic comparison of isolatedmenisci.35 However, definitive results are not yet available.

Complex tears were encountered in 20 horses and inMM mainly involved the distal half of the meniscus whenit was not prolapsed. Complex tears were the most com-mon lesion type in the LM. In the human literature, hor-izontal and oblique tears may not always be related tosymptoms and radial, vertical, complex, or displacedmeniscal tears are found exclusively on the symptomaticside and appear to be clinically more meaningful.15

Denoix and colleagues report that acute lesions are morefrequent in the corpus of the MM after a trauma or afall.10 Chronic degenerative lesions with rupture of fibers,increased cellularity, and medial prolapse are more fre-quently observed in horses presenting a slow evolution ofdegenerative joint disease.10 According to the same au-thors, lateral meniscal tears are usually in the cranial hornand are fissure, cleavage, and dilacerations.10 Injuries tothe caudal portion of the meniscus were not always exam-ined in our study because the examination through theextensive musculature at the caudal aspect of the stifle,which requires a low frequency convex probe, is not rou-tinely realized in our institution. Therefore, lesions of thecaudal horn of the menisci could have been underesti-mated in the current study. However, the damage of thecaudal meniscal horn alone is unusual (Busoni V, personalcommunication).

Modifications of size, shape, or position are signs of pro-lapse of the menisci.3 Prolapses were encountered in 20 ofthe 74 horses in the current study, whereas they were seenin 13 menisci of the 14 cases of the study of Flynn andWhitcomb.9 Group 3 had a great proportion of prolapsedmenisci (3 LM and 1 MM), group 2 had 1 prolapse of aLM, and 15 prolapsed menisci were seen among the 54MM of group 1. When prolapsed, the 16 damaged MMpresented eight complex lesions. In humans, a reportquotes that all the displaced tears are associated withtrauma, and full-thickness and displaced meniscal lesionsare rarely seen in asymptomatic knees.15 When prolapsed,the meniscus is displaced and is protruded beyond thefemoral and tibial condyles. A collapse of the femorotibialjoint can be seen radiographically in association with menis-cal prolapse36 but has not been reported in this study.

Three menisci presented hyperechogenic areas inter-preted as calcifications. Bone metaplasia of the MM haspreviously been described.3 Gross postmortem examina-tion confirmed the bone metaplasia in some previous re-ports.3 Hyperechoic images can either be a mineralizedtissue (without acoustic shadowing) or a zone of osseousmetaplasia (with acoustic shadowing).8 Calcificationwithin the meniscus or more chronic meniscal damagecould also give images of hyperechoic areas casting acous-tic shadows6 because of the difficult cicatrization.8

Synovial effusion of one or more recesses was encoun-tered in 51 of the 74 horses included in this study (69%).A previous similar study reported a higher number of syn-ovial effusions: 12 effusions of the femorotibial joints



among 14 horses with meniscal lesions.9 A positive corre-lation between synovial effusion of the MFT joint andmedial meniscal damage and between synovial effusion ofthe LFT joint and lateral meniscal damage was demon-strated in this study. Correlation between the affectedsynovial recess and the meniscal damage had not beenpreviously reported.

Fifteen of the 40 distended MFT joints in this studypresented hyperechoic dots in suspension without acous-tic shadowing in the anechogenic synovial fluid (37.5 %).In the MFT recess, hyperechoic dots without acousticshadowing floating in the anechogenic synovial fluid canbe found and have been described by previous authors asmeniscal debris, cartilaginous debris, fibrine clots,7 calci-fied bodies, air bubbles after arthrocentesis,2 or chondro-calcinosis.37 Movements of these dots can be induced bychanging the pressure on the examined recess. These dotstend to adhere to the synovial wall cavity and are liberatedinto the synovial fluid when the horse is moving. In hu-mans, particles most commonly identified in synovial fluidof osteoarthritic knees are basic calcium phosphates(mainly hydroxyapatite and calcium pyrophosphate dihy-drate).38 Ultrasonography demonstrated a high sensitivityand specificity in identifying these particles.39 In the vet-erinary literature, no study is available concerning the na-ture of the synovial fluid of the femorotibial joints in re-lation with these hyperechoic dots.

The synovial effusion of the cFT recess has not beenwell documented in previous reports.2 Ultrasonograph-ically, the cFT effusion is a synovial effusion that can beseen deep to the infrapatellar fat pad close to the cFTspace and close to the cranial meniscal horns.10 This cFTeffusion corresponds either to the MFT or to the LFT re-cess distended cranially. In 5% of the horses, a communi-cation between the MFT and the LFT joints can be pre-sent.40 The site of communication is situated cranially andproximally to the cranial cruciate ligament,40 close to thearea where cFT effusion is seen ultrasonographically.

Lesions of the cranial meniscal ligaments diagnosed onthe flexed hindlimbs could have been underestimated be-cause stifle flexion was not always tolerated. Medial collat-eral ligament desmitis were found in 5 of 74 horses.Previous reports quoted more medial collateral ligamentdesmitis than the current study: 7 of 77 horses with stiflelameness in Flynn and Whitcomb study9 and 4 cases ofdesmitis of the medial collateral ligament or lateral collat-eral ligament out of 20 horses suspected of stifle pathol-ogy in another report.24

Degenerative signs were more frequently seen with ul-trasonography (59%) than on radiographs (49%) and didnot concern all horses. In a previous study, nearly all horseshad degenerative joint disease at the side of the meniscalinjuries.9 Other authors reported 24 horses with abnormalradiographs of 29 cases with meniscal tears (83%).31

Degenerative joint disease should be considered as suspi-

cious for meniscal injury but the absence of degenerativejoint disease should not rule out meniscal injury.

Although no correlation between the type of meniscaldamage and the outcome was found, the high incidenceof poor outcome in the current study suggests a poorprognosis of femorotibial joint damage and in particularof meniscal damage. The outcome was evaluated mainlyfor crossbreeds and light breeds used for general purposeand showjumping. This population matched with thenormal hospital caseload. In the study of Flynn andWhitcomb,9 only 1 horse of 14 was able to return to hisprevious exercise level. Butler and colleagues41 also assertthat meniscal injuries have a poor prognosis.

CONCLUSIONSThis study demonstrates the high prevalence of meniscaltears and synovitis in horses with abnormal ultrasonogra-phy of the stifle. Based on this series of clinical cases, hor-izontal hypoechoic lesions (type 2) of the MM appear tobe the most frequent soft tissue injury of the equine stifledetected with ultrasonography. Central hypoechogenicareas with irregular margins (type 1) occur more fre-quently in the MM than in the LM. The LM often are af-fected by complex lesions (type 5).

ACKNOWLEDGMENTS

The authors thank Laurent Massart for his help in the sta-tistical analysis.

REFERENCES

1. Denoix JM, Crevier N, Perrot P, Bousseau B. Ultrasound examina-

tion of the femorotibial joint in the horse. Proc Am Assoc Equine

Pract 1994;40:57–58.

2. Denoix JM. Ultrasonographic examination in the diagnosis of joint

disease. In: McIlwraith CW, Trotter GW, eds. Joint disease in the

horse. Philadelphia: WB Saunders; 1996:165–202.

3. Denoix JM, Lacombe V. Ultrasound diagnosis of meniscal injuries

in horses. Pferdeheilkunde 1996;12:629–631.

4. Denoix JM, Perrot P, Vaslin C, Bousseau B. L’examen écho-

graphique de l’articulation fémoro-patellaire chez le cheval. Prat

Vét Equine 1996;28:105–115.

5. Denoix JM. Joints and miscellaneous tendons. In: Rantanen NW,

McKinnon AO, eds. Equine diagnostic ultrasonography. Philadel-

phia: Williams and Wilkins; 1998:475–514.

6. Reef VB. Musculoskeletal ultrasonography. In: Reef VB, ed. Equine

diagnostic ultrasound. Philadelphia: WB Saunders; 1998:160–164.

7. Denoix JM. Ultrasonographic examination of joints in horses. In

depth: ultrasonography of joints. Proc Am Assoc Equine Pract

2001;47:366–375.

8. Denoix JM, Jacquet S, Audigié F, Didierlaurent D. Examen

échographique des ménisques du cheval. Med Vét Québec

2002;32:119–122.

9. Flynn KA, Whitcomb MB. Equine meniscal injuries: a retrospective

study of 14 horses. Proc Am Assoc Equine Pract 2002;48:249-254.



10. Denoix JM, Audigié F, Coudry V. Lésions ligamentaires et ménis-

cales du grasset chez le cheval. Prat Vét Equine 2004;36:7–12.

11. De Smet AA, Tuite MJ, Norris MA, Swan JS. MR diagnosis of

meniscal tears: analysis of causes of errors. Am J Roentgenol

1994;163:1419–1423.

12. Jerosch J, Castro WH, Assheuer J. Age-related magnetic resonance

imaging morphology of the menisci in asymptomatic individuals.

Arch Orthop Trauma Surg 1996;115:199–202.

13. Helms CA. The meniscus: recent advances in MR imaging of the

knee. Am J Roentgenol 2002;179:1115–1122.

14. Bhattacharyya T, Gale D, Dewire P, Totterman S, Gale ME,

McLaughlin S, et al. The clinical importance of meniscal tears

demonstrated by magnetic resonance imaging in osteoarthritis of

the knee. J Bone Joint Surg Am 2003;85:4–9.

15. Zanetti M, Pfirrmann CW, Schmid MR, Romero J, Seifert B,

Hodler J. Patients with suspected meniscal tears: prevalence of ab-

normalities seen on MRI of 100 symptomatic and 100 contralateral

asymptomatic knees. Am J Roentgenol 2003;181:635–641.

16. Costa CR, Morrison WB, Carrino JA. Medial meniscus extrusion

on knee MRI: is extent associated with severity of degeneration or

type of tear? Am J Roentgenol 2004;183:17–23.

17. Lerer DB, Umans HR, Hu MX, Jones MH. The role of meniscal

root pathology and radial meniscal tear in medial meniscal extru-

sion. Skeletal Radiol 2004;33:569–574.

18. Meister K, Indelicato PA, Spanier S, Franklin J, Batts J. Histology

of the torn meniscus: a comparison of histologic differences in

meniscal tissue between tears in anterior cruciate ligaments-intact

and anterior cruciate ligament-deficient knees. Am J Sports Med

2004;32:1479–1483.

19. Latimer FG, Kaneps AJ, Pasquini C. Stifle disease in horses.

Compend Contin Educ Pract Vet 2000;22:381–390.

20. Van Weeren PR, Nixon AJ. Closing in on the equine joint. Equine

Vet J 2005;37:493–494.

21. Selby B, Richardson ML, Nelson BD, Graney DO, Mack LA.

Sonography in the detection of meniscal injuries of the knee: eval-

uation in cadavers. Am J Roentgenol 1987;149:549–553.

22. Cauvin ERJ, Munroe GA, Boyd JS, Paterson C. Ultra-

sonographic examination of the femorotibial articulation in

horses: imaging of the cranial and caudal aspects. Equine Vet J

1996;28:285–296.

23. Busoni V, Valentini S, Snaps F. Ultrasonographic assessment of cra-

nial meniscal ligaments in the horse. In: Proc 9th Annual

Conference of the European Association of Veterinary Diagnostic

Imaging; 2003:39.

24. Hoegaerts M, Saunders JH. How to perform a standardized ultra-

sonographic examination of the equine stifle. Proc Am Assoc

Equine Pract 2004;50:212–218.

25. Coudry V, Denoix JM. Ultrasonography of the femorotibial col-

lateral ligaments of the horse. Equine Vet Educ 2005;17:

275–279.

26. Hoegaerts M, Nicaise M, Van Bree H, Saunders JH. Cross-sec-

tional anatomy and comparative ultrasonography of the equine me-

dial femoro-tibial joint and its related structures. Equine Vet J

2005;37:520–529.

27. Walmsley JP. Vertical tears of the cranial horn of the meniscus and

its cranial ligament in the equine femorotibial joint: 7 cases and

their treatment by arthroscopic surgery. Equine Vet J

1995;27:20–25.

28. Walmsley JP. Cruciate, meniscal, and meniscal ligamental injuries.

In: Robinson NE, ed. Current Therapy in Equine Medicine.

Philadelphia: WB Saunders; 1997:84–88.

29. Peroni JF, Stick JA. Evaluation of a cranial arthroscopic approach

to the stifle joint for the treatment of femorotibial joint disease in

horses: 23 cases (1998-1999). J Am Vet Med Assoc

2002;220:1046–1052.

30. Walmsley JP, Phillips TJ, Townsend HGG. Meniscal tears in horses:

an evaluation of the clinical signs and arthroscopic treatment of 80

cases. Equine Vet J 2003;35:402–406.

31. Schramme MC, Jones RM, May SA, Dyson SJ, Smith RK.

Comparison of radiographic, ultrasonographic and arthroscopic

findings in 29 horses with meniscal tears. In: Proceedings of the

12th Annual Congress of the European Society for Veterinary

Orthopedic Traumatology; 2004:186.

32. Walmsley JP. Diagnosis and treatment of ligamentous and meniscal

injuries in the equine stifle. Vet Clin North Am Equine Pract

2005;21:651–672.

33. Walmsley JP. Stifle. In: Ross MW, Dyson SJ, eds. Diagnosis and

management of lameness in the horse. Philadelphia: WB Saunders;

2003:455–470.

34. Denoix JM. Anatomie fonctionnelle et biomécanique du genou et

du tarse chez le cheval. Swiss Vet 1991;8:48–57.

35. De Busscher V, Schreder A, Busoni V, Cassart D, Antoine N,

Gabriel A. Histological study of the horse stifle menisci in relation

with ultrasonographic aspect: preliminary study. Ital J Anat

Embryol 2006;111:15.

36. Denoix JM. Examen radiographique du grasset du cheval.

Sémiologie radiographique et lésions. Point Vét 1986;18:219–233.

37. Farina A, Filippucci E, Grassi W. La semeiotica ecografica del liq-

uido sinoviale. Reumatismo 2002;54:261–265.

38. Pattrick M, Hamilton E, Wilson R, Austin S, Doherty M.

Association of radiographic changes of osteoarthritis, symptoms,

and synovial fluid particles in 300 knees. Ann Rheum Dis

1993;52:97–103.

39. Frediani B, Filippou G, Falsetti P, Lorenzini S, Baldi F, Acciai C, et

al. Diagnosis of calcium pyrophosphate dihydrate crystal deposition

disease: ultrasonographic criteria proposed. Ann Rheum Dis

2005;64:638–640.

40. Barone R. Articulation du genou. In: Barone R, ed. Anatomie com-

parée des mammifères domestiques, 3rd ed., Tome 2: Arthrologie

et Myologie. Vigot; 1989:223–354.

41. Butler JA, Colles CM, Dyson SJ, Kold SE, Poulos PW. In: Butler

JA, Colles CM, Dyson SJ, eds. The stifle and tibia. In: Butler JA,

Colles CM, Dyson SJ, eds. Clinical radiology of the horse, 2nd ed.

Oxford, UK: Blackwell Science; 1993:285–326.


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