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Surgery Department, Faculty of veterinary medicine, Alexandria University. Abstract ..... Ed. WB Sounders Company, Philadelphia, Pennsylvania. PP 145-164.

Alexandria Journal of Veterinary Sciences www.alexjvs.com AJVS. Vol. 51(2):58-73. November 2016 DOI: 10.5455/ajvs.223225 Radiographic and Computed Tomographic Evaluation of the Carpal and Tarsal Joints in Apparently Healthy Donkeys Swidan-Dina, Nouh S.R., El Kammar M.H., Abu Ahmed-Howaida M. Surgery Department, Faculty of veterinary medicine, Alexandria University

Abstract Key words: Carpal joint; Tarsal joint: radiography; computed tomography

Correspondence to: Dina Swidan Swidan ([email protected] hoo.com

The current study was achieved to provide a detailed radiographic and computed tomographic anatomic reference of the carpal and tarsal joints in Donkey with evaluation of both radiography and computed tomographic modalities. 13 adult apparently healthy donkey were used. All limbs were disarticulated at the stifle joint in case of hind limbs and at the elbow joint in case of fore limbs. Both carpi and tarsi of each animal were subjected to computed radiography in three views; Dorsopalmar or dorsoplantar, lateromedial and dorsolateral palmaromedial oblique or dorsolateral plantaromedial oblique. Computed tomographic scanning was done in different planes; transverse, sagittal, dorsal and three dimensional planes. Both radiography and computed tomography modalities were evaluated concerning the time needed for the technique, resolution, cost and availability. The dorsopalmar view of the carpal joint showed three articulations; radiocarpal joint, middle carpal joint and carpometacarpal joint, as well as, the 1st carpal bone that appeared as a radio-opaque circular mass behind the 2nd carpal bone. Dorsoplantar view of the tarsal joint showed four levels of articulations and the 4 th tarsal bone was superimposed with central tarsal bone and 3 rd tarsal bone. Both 2nd and 4th metatarsal bones were superimposed. In the lateral view of the carpal joints, the joints were well defined but carpal bones of each row appeared superimposed. In the lateral view of the tarsal joint, the lateral and medial ridges of trochlea tali, sustentaculum tali and the trochlear groove were all apparent in this view. The dorsolateral palmaromedial oblique view showed that the 4th and the ulnar carpal were more apparent but the second metacarpal bone was totally superimposed with the 3 rd metacarpal bone. The dorsolateral plantaromedial oblique view showed that the 4th metatarsal bone was well defined and wasn’t superimposed but the 2nd metatarsal bone appeared superimposed with the 3rd metatarsal bone. The computed tomographic scanning showed that the carpal canal was well delineated. The lateral and medial collateral tendons, long tendon of ulnaris lateralis muscle, flexor carpi ulnaris (tendinous part) and the flexor carpi radialis tendon had the same bright gray degree. The extensor carpi radialis, common digital extensor tendon and extensor carpi obliquus tendons had a bright gray shade and were well delineated on the dorsal surface of trochlea radii. In the tarsal joint, the long digital extensor tendon was well defined along all levels of the tarsal joint especially at the level of middle talus, proximal and distal intertarsal joints and tarsometatarsal joint. The lateral digital extensor tendon was well delineated at the level of proximal inetertarsal, distal intertarsal and tarsometatarsal joint. The computed tomography was better than radiography in contrast and spatial resolution but it needed much time and cost than the radiography.

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old. This study was approved by the institutional animal use and care committee at faculty of veterinary medicine, Alexandria University. Euthanasia was performed by chloral hydrate 10 % at a dose of 15 mg/ 50kg intravenously. All limbs were disarticulated at the stifle joint in case of hind limbs and at the elbow joint in case of fore limbs. Both carpi and tarsi of each animal were preserved under -20 for 24 hrs for further imaging. Prior to imaging, limbs were thawed till joints restored their flexibility. All joints were subjected to computed radiography in three views; Dorsopalmar / dorsoplantar, lateromedial and oblique dorsopalmar / oblique dorsoplantar. Radiographically normal joints were subjected to computed tomographic imaging for computed tomographic anatomy. Also two different slice thicknesses were used; 0.1mm and 0.2 mm. Both bone and soft tissue windows were used. The joints that proved normal in X-ray and C.T imaging were used a cross section anatomical slices to be used as a guide for the computed tomographic anatomy. Limbs were frozen again at -20 for a couple of days in the extended position then cut by the electric band saw into 1 cm thickness slices to correlate the anatomic cross sections with the C.T images of the same joint. Both radiography and computed tomography modalities were evaluated concerning the time needed for the technique, resolution, cost and availability.

1. INTRODUCTION The donkey is an important farming animal used heavily by the Egyptian farmers because of their great tolerance as a draught animal (Pollard and Puchalski, 2011). In Egypt 90% of equines are used primarily for carrying heavy loads and, to some extent, for riding. They are utilized mostly by farmers as a mean of cheap transportation beside work for cultivating land so they play a significant role in Egyptian economy (El-Kasapy, 2013). The computed tomography (CT) is efficient imaging modality that provides a cross-sectional image with superior soft tissue differentiation and no superimposition of the overlying structures, which can be used for better diagnosis of foot abnormalities (Badawy, 2011). The computed tomography through its high spatial resolution and moderate differentiation of tissue contrast is a fastened exceptionally useful technique for visualizing general anatomy (Dixon and Dacre, 2005). CT and MR imaging offer superior diagnostic possibilities over conventional radiography because of two primary advantages, which are their tomographic nature and increased contrast resolution. Indeed, as opposed to radiographs that represent twodimensional, or flat, projections of three-dimensional structures, tissues are examined with CT and MRI in thin sections, or slices, thereby eliminating superimposition (D’Anjou, 2013). Accurate interpretation of CT of the foot requires a thorough knowledge of the cross-sectional anatomy of the region and accurate interpretation of the plan metric CT is necessary for the study and evaluation of the pathological condition or damaged tissues, CT is particularly useful for looking at complex bony structures such as the skull, spine or joints (Raji et al. 2008). The study is aimed to provide a detailed radiographic and computed tomographic anatomic reference for the equine carpal and tarsal joints in conjugation with cross anatomical sections as a guide for the computed tomography in addition to the three-dimensional imaging, as well as, comparing between both C.T and radiography concerning the contrast resolution, spatial resolution, cost, time needed and availability.

3. RESULTS A- Surgical radiographic anatomy 1- The carpus Dorsopalmar view The carpal joint consisted of three articulations; radiocarpal joint, middle carpal joint and carpometacarpal joint. The radiocarpal joint is located between the carpal articular surface of the radius and the proximal row of carpal bones. The middle carpal joint is situated between the proximal and distal carpal row. The carpometacarpal joint is situated between the distal carpal row and the 2nd, 3rd and 4th metacarpal bones. The carpal joint consisted of two rows of bones. The proximal row consisted of the radial, intermediate and ulnar carpal bones from and the distal row included the 2nd, 3rd and 4th carpal bones from medial to lateral. The 1st carpal bone was reported in all carpal joints in the study (Fig. 1).

2. MATERIALS AND METHODS The present study was carried out on 13 apparently healthy donkeys, their ages ranged from 1 to 7 years Lateral view 59

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The joints are well defined but carpal bones of each row appeared superimposed. The radial carpal bone appeared the most dorsal and its dorso-distal border was sharply defined and well fitted with the dorsoproximal surface of the 3rd carpal bone. The accessory carpal bone was discoidal in shape, well defined and caudally extended. The 1st carpal bone was also totally viewed and resting behind the 2nd carpal bone (Fig. 2). Oblique dorsopalmar The 4th and the ulnar carpal were more apparent than in the lateral view. The lateral styloid process was apparent & superimposed partially with accessory carpal bone. Fig.1: Dorsopalmar view of the left carpal joint: 1-medial styloid process 2-lateral border of medial styloid process 3-projection at the proximo medial aspect of medial styloid process 4- Lateral styloid process 5-vascular channels 6-radial carpal bone 7-accessory carpal bone 8-intermediate carpal bone 9-ulnar carpal bone 10- Second carpal bone 11- Third carpal bone 12- Fourth carpal bone 13- Second metacarpal bone 14- Fourth metacarpal bone 15- Third metacarpal bone -Note the border of the 1st carpal bone (black arrowheads) - Note the radiolucent canal between the radial na intermediate carpal bones

Fig.2: lateral view of the left carpal joint: 1-Ridges on cranial surface of radius 2. Ridge adjacent to lateral border of common digital extensor tendon 3-Transverse crest of radius 4-caudal border of radial trochlea 5-dorsal surface of intermediate carpal bone 6-dorsal surface of ulnar carpal bone 7- Dorsal surface of radial carpal bone 8-dorsal surface of 3rd carpal bone 9-dorsal surface of 4th carpal bone 10-dorsal surface of 2nd carpal bone 11- 1st carpal bone 12- Accessory carpal bone 13-3rd metacarpal bone 14- 2nd metacarpal bone

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Fig.3: Dorsolateral palmaromedial oblique view of the left carpal joint: 1-medial part of radial trochlea 2. lateral styloid process 3- 4th metacarpal bone 4-radial carpal bone 5-intermediate carpal bone 6-ulnar carpal bone 7- accessory carpal bone 8- 3rd carpal bone 9- 2nd carpal bone 10- 4thcarpal bone 11- 2nd metacarpal bone 12- 3rd metacarpal bone

Fig.4: Dorsoplantar view of the left tarsal joint: 1-Tuber calcanei 2-Calcaneus bone 3-Medial groove of tibial cochlea 4-Lateral groove of tibial cochlea 5-Medial malleolus of tibia 6-Lateral malleolus of tibia 7-Oblique ridge separating between medial and lateral grooves of tibial cochlea 8-Lateral talar ridge 9-Medial talar ridge 10-Distal tubercle of talus 11-Proximal intertarsal joint 12-Central tarsal bone 13-Distal intertarsal joint 14-tarsometatarsal joint 15-base of 2nd metatarsal bone 16- base of 4th metatarsal bone 17- 4th tarsal bone 18- 3rd tarsal bone Fig.5: lateral view of the left tarsal joint: 1-tibiotarsal joint 2-Tuber calcanei 3- sustentaculumtali 4-lateral talar ridge 5-medial talar ridge 6- groove of trochlea talii 7-proximal intertarsal joint 8- distal intertarsal joint 9- tarsometatarsal joint 10- central tarsal bone 11- 3rd tarsal bone 12- 1st and 2nd fused tarsal bones 13- base of 3rd metatarsal bone 14- base of 2nd metatarsal bon 15- base of 4th metatarsal bone

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The 4th metacarpal bone wasn’t superimposed but the second metacarpal bone was totally superimposed with

the 3rd metacarpal bone and was articulated with the 2nd carpal bone, (Fig. 3). 2-The tarsus Lateral view The lateral and medial ridges of trochlea tali, sustentaculum tali and the trochlear groove were all apparent in this view. The calcaneus and tuber calcanei ware also clear and well defined. The 1st and 2nd tarsal bones were fused and articulating with the central tarsal bone, (Fig.5). Oblique dorsoplantar

Dorsoplantar view The tarsal joint had four articulations; tarsocrural, proximal intertarsal, distal intertarsal and tarsometatarsal joint. The tarsocrural joint located between the cochlea of tibia and the trochlea of talus. The proximal intertarsal joint situated between the talus and calcaneus proximally and central and 4th tarsal bone distally. The distal intertarsal joint located between the central tarsal bone and the 1st, 2nd tarsal bones and 3rd tarsal bone. The 1st and 2nd tarsal bone were fused. The tarsometatarsal joint located between the 1st, 2nd, 3rd and 4th tarsal bones proximally and the 2nd, 3rd and 4th metatarsal bones distally. The calcaneus bone was elongated, located laterally and was oblique toward the medial aspect of joint. It was also superimposed with talus bone and the distal extremity of tibia. The 4th tarsal bone was superimposed with central tarsal bone and 3rd tarsal bone. Both 2nd and 4th metatarsal bones were superimposed, (Fig.4).

The lateral malleolus and the cranial aspect of intermediate ridge of tibial cochlea were clear in this view. The intermediate ridge of tibial cochlea was resting between the lateral and medial ridges of talus. The 4th tarsal bone was clear and lied beneath the calcaneus. The 4th metatarsal bone was well defined and wasn’t superimposed but the 2nd metatarsal bone appeared superimposed with the 3rd metatarsal bone, (Fig.6).

Fig.6: dorsolateral plantaromedial oblique view of the left tarsal joint: 1-Medial malleolus of tibia 2-Distal projection of medial malleolus 3-Medial talar ridge 4-Lateral talar ridge 5-Tuber calcanei 6-Calcaneus bone 7-Proximal intertarsal joint 8-Distal intertarsal joint 9-Tarsometatarsal joint 10-Central tarsal bone 11-3rd tarsal bone 12-4th tarsal bone 13-2nd metatarsal bone 14-3rd metatarsal bone 15-4th metatarsal bone 16-Dorsal opening of the tarsal canal 17-Plantar opening of tarsal canal 18- Intermediate ridge of tibial cochlea Black arrow head: non-articular area between central & 3rd tarsal bones

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It included three bones; 2nd, 3rd and 4th metacarpal bones and the 1st carpal bone presented in all animals under the study (Fig.10 &11). 1.1.D. At the level of proximal third of metacarpus It included three bones; 2nd, 3rd and 4th metacarpal bones. The 3rd carpal bone was the largest and situated in the middle and articulating with 2nd metacarpal (Fig.12). 1.2. Sagittal plane It resembles the lateromedial view of radiographs but eliminating the superimposition (Fig.15). 1.3. Dorsal plane It resembles the dorsopalmar radiographic view. The anatomical details of the dorsal, middle and palmar aspect of carpal joint are illustrated in, (Fig.14).

B-Computed tomographic of the carpal joint 1-The carpal joint (bone window) 1.1. Transverse plane 1.1.A. At the level of distal extremity of radius The radius distal extremity is the only viewed bone in this plane and the fossa in the middle of its caudal surface got clearer toward the radiocarpal joint, (Fig.7 &8). 1.1.B. At the level of proximal carpal row The radial, intermediate and ulnar carpal bone were well delineated with the intercarpal joints clear between each articulating bones (Fig. 9). 1.1.C. At the level of distal carpal row

1.4. Three dimensional view The carpal joint was viewed as a three dimensional structure from all directions showing all the bony prominences and bones alignment. The carpal joint was complex with the accessory carpal and 1st carpal bones the most protruding bones from this joint, (Fig.13).

Fig.7: Transverse scan of the carpal joint at the level of distal extremity of radius 1.radius 2.ulna 3. Common digital extensor tendon 4. Extensor carpi radialis tendon.

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Fig.8: Transverse scan of the carpal joint at the level of Trochlea radii 1.radius (a. medial aspect, b. lateral aspect) 2. Extensor carpi radialis tendon 3. Common digital extensor tendon 4. Extensor carpi obliquus tendon. 5. Lateral collateral ligament 6. Medial collateral ligament 7. Flexor retinaculum 8. Flexor carpi radialis tendon 9. Flexor carpi ulnaris muscle with tendinous part (hyperdense) and muscle part (hypodense). 10. Ulnaris lateralis muscle with long tendon (hyperdense) 11. Deep digital flexor tendon 12. Superficial digital flexor tendon.

Fig.9: Transverse scan of the carpal joint at the level of proximal carpal row. 1. Radial carpal bone 2.Intermediate carpal bone 3. Ulnar carpal bone 4.Accessory carpal bone 5. Extensor carpi radialis tendon 6.Common digital extensor tendon 7. Lateral collateral ligament 8. Medial collateral ligament 9.Dep digital flexor tendon. 10. Superficial digital flexor tendon.

Fig 10: Transverse scan of the carpal joint at the level of distal carpal row (middle). 1. Second metacarpal bone 2. Third metacarpal bone 3.fourth carpal bone 4. Extensor carpi radialis 5. Common digital extensor tendon 6.Lateral collateral ligament 7.palmar carpal ligament 8. Deep digital flexor tendon 9. Superficial digital flexor tendon.

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Fig.11: Transverse scan of the carpal joint at the level of distal carpal row (distal third). 1. First metacarpal bone 2. Second metacarpal bone 3. Third metacarpal bone 4.fourth carpal bone 5. Extensor carpi radialis6. Common digital extensor tendon 7.Lateral collateral ligament 8. Deep digital flexor tendon 9. Superficial digital flexor tendon. 10. Palmar carpal ligament 11.Flexor carpi radialis tendon.

Fig.12: Transverse scan of the carpal joint at the level of proximal part of metacarpus. 1. Second metacarpal bone 2. Third metacarpal bone 3. Fourth metacarpal bone 4.common digital extensor tendon 5. Lateral digital extensor tendon 6. Deep digital flexor tendon 7. Superficial digital flexor tendon 8. Accessory ligament of DDF 9. Medial palmar artery.

Fig.13: Three dimentionalviews of the carpal joint. A.dorsopalmarview B.Lateral view C. mediolateral view D.palmar view. Ra.RadiusR.radial carpal bone I.intermediate carpal bone U.ulnar carpal bone 1.first carpal bone 2.second carpal bone 3.third carpal bone 4.fourth carpal bone Mc2.second metacarpal Mc3. Third metacarpal Mc4 .fourth metacarpalA.accessory carpal bone. Black arrow: 1 st carpal bone.

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Fig.14: Dorsal plane scans of the carpal joint from dorsal to caudal aspect (A) Swidan et al. 2016. AJVS 51(2):58-73. Dorsal third. (B) Middle third(C, D, E & F) Palmar third. 1. First carpal bone 2. Second carpal bone 3. Third carpal bone 4. Fourth carpal bone (MC2). Second metacarpal bone (MC3). Third metacarpal bone (MC4). Fourth metacarpal bone R. Radial carpal bone I. Intermediate carpal bone (U).Ulnar carpal bone(Ra). Radius A. Accessory carpal bone L. lateral styloid process. Arrows refers to the metaphyseal line.

Fig.15: sagittal scans of the carpal joint from medial to lateral. 1. first carpal bone 2.second carpal bone 3.third carpal bone (Ra).Radius (R). Radial carpal bone (I) intermediate carpal bone (U)ulnar carpal bone (A) Accessory carpal bone (MC2)second metacarpal bone (MC3) third metacarpal bone (MC4) fourth metacarpal bone.

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The fused 1st and 2nd tarsal bones was situated medially and articulating with the t-shaped 3rd tarsal bone in the middle. (Fig.20). 2.1.F. At the proximal third of metatarsus It included the 2nd metatarsal bones medially, the 3rd metatarsal bone in the middle and the 4th metatarsal bone laterally (Fig.21). 2.2. Sagittal plane Lateral, middle and medial aspect of joint are illustrated in, (Fig 23). 2.3 Dorsal plane Dorsal, middle and palmar aspects of joint are illustrated in, (Fig.22). 2.4. Three-dimensional view All bony prominences were well defined and the joint was viewed from all directions, (Fig.24).

2-Tarsal joint (bone window) 2.1 Transverse plane 2.1.A. At the level of distal extremity of tibia The scan included the distal tibia and the tip of calcaneus. (Fig.16). 2.1.B. At the level of proximal third of talus The lateral and medial ridges of trochlea of talus are well defined and a part of the intermediate ridge of cochlea of tibia was resting between ridges of talus, (Fig.17). 2.1.C. At the midlevel of talus The lateral and medial ridges and the groove of trochlea tali were apparent. The sustentaculum tali was well delineated, (Fig.18). 2.1.D. At the level of proximal intertarsal joint The central tarsal bone was articulating with 4th tarsal bone laterally forming S-shape structure, (Fig.19). 2.1.E. At the level of distal intertarsal joint The carpal canal was well delineated and surrounded dorsally by the palmar carpal ligament, laterally by the accessory carpal bone and palmaromedially by transverse carpal ligament. The lateral and medial collateral tendons, long tendon of ulnaris lateralis muscle, flexor carpi ulnaris (tendinous part) and the flexor carpi radialis tendon all had the same bright gray degree.

3. Soft tissue window. 3.1. Carpus: C-Technical results The 0.2 mm thickness C.T scans (120 kV, 112 mA) was found to have a better resolution than the 0.1 mm thickness scans (110 kV, 50 mA). The 0.2 mm scans was better in viewing the trabecular pattern of bones and also in differentiating

3.2. Tarsus: The long digital extensor tendon was well defined along all levels of the tarsal joint especially at the level of middle talus, proximal and distal intertarsal joints and tarsometatarsal joint. The lateral digital extensor tendon was well delineated at the level of proximal inetertarsal, distal intertarsal and tarsometatarsal joint.

Fig.16: Transverse scan of the tarsal joint at the level of distal extremity of tibia: 1.tibia 2.calcaneus bone 3.long digital extensor tendon 4.peroneus tertius (4a lateral lobe, 4b medial lobe) white arrow: tendon of tibialis cranialis ms 5.tibialis cranialis muscle 6.medial collateral ligament 7.tendon of medial head of deep digital flexor ms 8.lateral digital extensor tendon 9. Tendon of lateral head of deep digital flexor ms 10. Superficial digital flexor tendon (10a medial retinaculum of SDFT, 10b lateral retinaculum of SDFT) 11. Medial collateral ligament.

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Fig.17: Transverse scan of the tarsal joint at the level of tibiotarsal joint: Talm. Medial talar ridge Tal l. lateral talar ridge I.intermediate ridge of cochlea tibii ( cranial & caudal parts) M.Tibia(medial malleolus) Ca. calcaneus bone DM. Dorsomedial recess 1.long digital extensor tendon 2.tibialis cranialis muscle (2a lateral branch, 2b cuneus branch) 3.lateral digital extensor tendon 4.lateral collateral ligament 5.medial collateral ligament 6.tendon of lateral head of deep digital flexor 7.Tendon of lateral head of DDF. 8. Superficial digital flexor tendon.

Fig.18: Transverse scan of the tarsal joint at the level of midlle of talus: Talm. Medial talar ridge Tal l. lateral talar ridge Ca. calcaneus bone Ca sus: sustentaculumtalii DM. Dorsomedial recess DL. Dorsolateral recess PM. Plantaroedial recess 1.long digital extensor tendon 2.tibialis cranialis muscle (2a lateral branch, 2b cuneus branch) 3.Tendon of medial head of deep digital flexor 4 tendon of lateral head of DDF5.superficial digital flexor tendon 6.long plantar ligament 7.lateral collateral ligament 8. Lateral digital extensor tendon.

Fig.19: Transverse scan of the tarsal joint at the level of proximal intertarsal joint : Tal: talus DM. Dorsomedial recess DL. Dorsolateral recess 1.long digital extensor tendon 2.lateral digital extensor tendon 3.lateral collateral ligament 4.medial collateral ligament5. Tendon of lateral head of DDF 6.tendon of medial head of DDF 7.Superficial digital flexor tendon 8.long planar ligament (8a.lateral part, 82. Medial part).

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Fig.20: Transverse scan of the tarsal joint at the level of distal intertarsal joint: 1.long digital extensor tendon 2.lateral digital extensor tendon 3.third tarsal bone 4. Fourth tarsal bone 5.tendon of medial head of deep digital flexor ms 6. Tendon of lateral head of DDFT 7.superficial digital flexor tendon 8.distal plantar ligament 9.long plantar ligament 10.lateral collateral ligament.

Fig.21: Transverse scan of the tarsal joint at the level of tarsometatarsal joint : 1.long digital extensor tendon 2.lateral digital extensor tendon 3.lateral collateral ligament 4. Medial collateral ligament 5.tendon of lateral head of DDF 6. Tendon of medial head of DDF 7.superficial digital flexor tendon 8.long plantar

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Fig.22: Dorsal scans on the tarsal joint from Dorsal to caudal aspect. A. Dorsal third B.middle third C.plantar third T.tibia MT2. Second metatarsal bone MT3. Third metatarsal bone MT4.fourth metatarsal bone Tal. Talus bone Talm.medialtalar ridge Tal l. lateral talar ridge Ca.calcaneus bone Tc.centraltasal bone T3. Third tarsal bone T4. Forth tarsal bone. T1+2: Fused 1st & 2nd tarsal bones.

Fig.23: sagittal scans on the tarsal joint from medial to lateral aspect. A. medial third B.middle third C.lateral third T.tibia MT2. Second metatarsal bone MT3. Third metatarsal bone MT4.fourth metatarsal bone Tal. Talus bone Ca.calcaneus bone Ca t. Calcaneal tuber Tc.centraltasal bone T3. Third tarsal bone T4. Forth tarsal bone. T1+2: Fused 1st & 2nd tarsal bones.

Fig.24: Three dimensional views of the tarsal joint. T.tibia Tm.medial malleolus Tal l.lateraltalar ridge Talm.medial talar ridge Ca. calcaneus bone Ca T. calcaneal tuber T1+2. Fused 1 st&2nd tarsal bones T3.third tarsal bone T4. Fourth tarsal bone Tc. Central tarsal bone MT2. Second metatarsal MT3. Third metatarsal MT4.Fourth metatarsal.

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the different layers of the limb including skin, ligament, tendons, muscles, retinaculum and bones. Some soft tissues were obvious through the 0.2mm bone window scans compared to 0.1mm bone window scans. The 0.2 mm scans viewed larger images than 0.1 mm scans. Table No1: Digital radiography and computed tomography were monitored through the following parameters:

diagnosis of many abnormalities in both carpal and tarsal joints, these results were similar to that reported by Walker et al. (1993). The carpal canal was well delineated and surrounded dorsally by the palmar carpal ligament, laterally by the accessory carpal bone and palmaromedially by tranverse carpal ligament. The lateral and medial collateral tendons, long tendon of ulnaris lateralis muscle, flexor carpi ulnaris (tendinous part) and the flexor carpi radialis tendon all had the same bright gray shade. The deep digital flexor tendon also had a bright gray shade but it was lighter than the superficial digital flexor tendon. The extensor carpi radialis, common digital extensor tendon and extensor carpi obliquus tendons had a bright gray shade and were well delineated on the dorsal surface of trochlea radii, all these findings are similar to that mentioned by Kaser-Hotz et al. (1994). The finding concerning the C.T description of the accessory ligament of the deep digital flexor tendon (DDFT) , it was more hypodense than the superficial digital flexor tendon (SDFT) and this disagreed with Kaser-Hotz et al. (1994) who mentioned that The accessory ligament of deep digital

4. DISCUSSION Radiography is a very useful tool in veterinary practice and is often the first ancillary imaging test when a pathological condition of a limb is suspected (O’Brien and Biller, 1996). In this study radiography has significant limitations in soft tissue evaluation together with many affections that couldn’t be observed radiographically in addition to superimposition of many anatomical structures, these results were in agreement with Dixon and Drace (2005). The description of the bony skeleton of the carpal joint given by Dyce et al.(2010) , Fayed (2010) and Frisbie.(2012) concerning the bones forming the joint and the shape of 1st and accessory carpal bones are similar to that in the present work. The carpal joint consisted of three articulations; antebrachiocarpal joint, middle carpal joint and carpometacarpal joint. These findings are similar to that mentioned by Dyce et al. (2010) and Frisbie (2012). Computed tomography has many advantages over the routine radiography as it provides detailed cross sectional images without superimposition and great visualization of soft tissues and it is used for better 71

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flexor tendon (DDFT) was lighter gray than superficial digital flexor tendon (SDFT). The present study showed that the tarsal joint had four articulations; tarsocrural, proximal intertarsal, distal intertarsal and tarsometatarsal joint. The tarsocrural joint was located between the cochlea of tibia and the trochlea of talus. The proximal intertarsal joint was situated between the talus and calcaneus proximally and central and 4th tarsal bone distally. The distal intertarsal joint was located between the central tarsal bone and the 1st, 2nd tarsal bones and 3rd tarsal bone. The 1st and 2nd tarsal bones were fused. The tarsometatarsal joint was located between the 1st, 2nd, 3rd and 4th tarsal bones proximally and the 2nd, 3rd and 4th metatarsal bones distally. These findings comes into an accordance with that recorded by Budras and sack (2012). In transverse scans of tarsus, the lateral digital extensor tendon was well delineated at the level of distal intertarsal and tarsometatarsal joints these findings were similar to that mentioned by Raes et al. (2011). In addition, the tendon was less well defined at the level of tarsocrural joint, distal extremity of tibia and middle of talus and this wasn’t mentioned by Raes at al. (2011). The spatial resolution, which is the ability of a modality to distinguish between two high contrast objects close to each other, was much better in C.T scans than in the digital radiographic images. The bone elements were well separated and distinguished from the neighboring soft tissues through the bone window scans and joint spaces were well detected while the neighboring bones in the radiographs had a border effacement and summation signs in the element of the joint . These findings disagreed with that reported by Bushberg et al. (2002) who stated that the digital radiography had a spatial resolution 0.17 mm compared with 0.4 mm in C.T.

The C.T provides a superior diagnostic modality with a higher spatial and contrast resolution compared with the digital radiography and the cross anatomical slices were useful in identification of tendons and ligaments. 6. References Badawy, M. 2011. Computed tomographic anatomy of the fore foot in one-Humped camel. Global veterinaria 6 (4): 417-423. Baxter, G. M. and Stashak, T.S. 2011. Adams and Stachak’s lamnessin horse. 6th Edition. Blackwell Publishing, ltd. Bjorklund, L. 1998. The bone and joint decade 2000–2010. In: Inaugural Meeting 17 and 18 April 1998, Lund, Sweden. Acta Orthop. Scand. Suppl. 281, 67–80. Budras, K. Sack and W.O. 2012. Anatomy of the Horse, 6th Edition ,Schlutersche Verlagsgesellschaft mbH & Co. KG. Bushberg JT, Seibert JA, Leidholdt EM Jr, et al. 2002. Digital radiography. In Bushberg JT, et al, editors: The essential physics of medical imaging, ed 2, Philadelphia, Lippincott Williams & Wilkins, p 293. D’Anjou, M. 2013. Textbook of veterinary diagnostic radiology. 6th Edition, pp: 50-53 Dixon, P. M. and Dacre, I. 2005. A review of equine dental disorders. Veterinary J., 169(2): 165-187. Dyce, K.M, Sack, W.O. and Wensing, C.J.G. 2010. Text book of veterinary anatomy, 4th edition W. B. Saunders company, Philadelphia, PA 19106; pp. 14-21, 573-610. El-Kasapy, A. 2013. Experimental studies on the Equine carpus. PhD thesis. PP: 1. Fayed, M.H. 2010. Architecture anf functional specification of the muscle of the antebrachium and manus region of the African Ass (Equus asinus) Advances in biological research 4 (1): 45-64, 2010. ISSN 1992-0067. IDOSI puplications, 2010. Frisbie, D.D. 2012. Synovial joint anatomy, biology and pathobiology. In Auer, J.A., ed.Equine surgery, 4 th edition W B. Saunders company. Kaser-Hotz, B., Sartoretti-Schefer, S. and Weiss, R. 1994. Computed tomography and magnetic reasonance imaging of the normal equine carpus. Vet RadioIUltrasound. 35:457-461.McNitt-Gray .2002. “Radiation dose in CT,” Radiographics 22:1541-1553 O’Brien, R. T. and Biller D. S. 1996. Clinical application of radiography and ancillary imaging. Veterinary clinical Nourth American food Animal practice, 12: 263-275. Park, R. D.; Steyn, P. F. and Wrigley, R. H. 1996. Imaging technique in the diagnosis of equine joint disease. In: joint disease in the horse. Mcllwraith C. W., TrotterG. W. 5 th Ed. WB Sounders Company, Philadelphia, Pennsylvania. PP 145-164. Pollard, R. and Puchalski, S. 2011. C.T contrast media and applications. In: Schwarz, T. and Saunders, J. (Eds.): veterinary computed tomography. Wiley-Blackwell, 2011 :57-65.

In the present study the spatial and contrast resolution of the bone and soft tissue window C.T scans was conversely related with the slice thickness. The 0.2 mm scans had a better contrast and spatial resolution than the thinner 0.1mm scans. Another factors was affecting the image quality and should be taken in consideration; the mAs and Kv used by the C.T apparatus. The 0.2 mm scans required 120 Kv and 112 mAs that was higher than that used for 0.1mm scans (110 Kv and 50 mAs). 5. Conclusions 72

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Pool, R.R. 1996. Pathologic manifestation of joint disease in the athletic horse. In: joint disease in the horse. Mcllwraith C. W., Trotter G. W.5th Ed. WB Saunders Company. PP.87-104 Raes, E. V., Bergman, E. H., Veen, H. V., Vanderperren, K., Vekens, E. V. and Saunders, J. H. 2011. Comparison of cross-sectional anatomy and computed tomography of the tarsus in horses. AJVR, Vol 72, No. 9, September 2011. Raji, A. R.; Sardari, K. & Mohammadi, H. R. 2008. Normal cross-sectional anatomy of the bovine digit: comparison of computed tomography and limb anatomy. Anat. Histol. Embryol., 37(3):188-91 Todhunter, R.J. and Lust, G. 1990. Pathophysiology of synovitis: clinical signs and examination in horses. Compend. Contin. Educ. Pract. Vet. 12:980-993. Walker, M., Hartsfield, S., Mathew, N, White, G., Slater, M., and Thoos, J. 1993. Computed radiography and blood gas analysisof anaesthetized blood hounds with induces pneumothorax, Vet. Rad. and ultrasound, 34: 93-98.

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