Long bones – mature

Hester McAllister; Emma Tobin

doi:10.22233/9781910443293.9

Long bones – mature

British Small Animal Veterinary Association , 108 (2016); https://doi.org/10.22233/9781910443293.9

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Long bones – mature

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Authors: Hester McAllister and Emma Tobin
From: BSAVA Manual of Canine and Feline Musculoskeletal Imaging
Item: Chapter 9, pp 108 - 132
DOI: 10.22233/9781910443293.9
Copyright: © 2016 British Small Animal Veterinary Association
Publication Date: January 2016

Abstract

The indications for radiography of the long bones are numerous and include: overt lameness attributed to pain or swelling of a limb on skeletal clinical examination; subtle lameness; discharging tracts; skeletal surveys for metastatic or infectious bone diseases. Sequential studies are advantageous in: assessing the degree of improvement or deterioration of a disease process; assessing healing and callus formation of fractures; reassessing an area that had equivocal initial radiographs. This chapter explains radiography, normal anatomy and abnormal image findings.

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Figures

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9.1

(a) Mediolateral (ML) and (b) craniocaudal (CrCd) views of the stifle of an adult dog. There is a subtle circular radiolucent area in the craniodistal aspect of the distal femoral metaphysis (arrowed). The CrCd view shows a faint periosteal reaction (arrowhead) on the distomedial aspect of the femoral diaphysis. This was an early malignant bone tumour. © 2016 British Small Animal Veterinary Association

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9.1 (a) Mediolateral (ML) and (b) craniocaudal (CrCd) views of the stifle of an adult dog. There is a subtle circular radiolucent area in the craniodistal aspect of the distal femoral metaphysis (arrowed). The CrCd view shows a faint periosteal reaction (arrowhead) on the distomedial aspect of the femoral diaphysis. This was an early malignant bone tumour.

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9.2

(a) CrCd view of the femur of a 30 kg German Shepherd Dog. A grid with medium-speed screens and latitude film have been used. There is good radiographic contrast showing bone and soft tissue detail but the distal femur is relatively overexposed compared with the proximal femur. The femoral diaphysis is underexposed owing to attenuation of the beam in the upper thigh muscles. (b) CrCd view of the femur of a 30 kg Labrador Retriever obtained using a digital system with correct settings. The soft tissue and bone detail throughout the length of the limb is excellent. The fabellae are clearly visible (arrowed). © 2016 British Small Animal Veterinary Association

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9.2 (a) CrCd view of the femur of a 30 kg German Shepherd Dog. A grid with medium-speed screens and latitude film have been used. There is good radiographic contrast showing bone and soft tissue detail but the distal femur is relatively overexposed compared with the proximal femur. The femoral diaphysis is underexposed owing to attenuation of the beam in the upper thigh muscles. (b) CrCd view of the femur of a 30 kg Labrador Retriever obtained using a digital system with correct settings. The soft tissue and bone detail throughout the length of the limb is excellent. The fabellae are clearly visible (arrowed).

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9.3

ML view of the distal tibia and fibula of a dog. Mach lines may be positive (arrowed) or negative (arrowhead) depending on the curvature and superimposition of the adjacent bones. © 2016 British Small Animal Veterinary Association

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9.3 ML view of the distal tibia and fibula of a dog. Mach lines may be positive (arrowed) or negative (arrowhead) depending on the curvature and superimposition of the adjacent bones.

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9.4

(a) ML view of the normal humerus of a Boxer. The arrow indicates the tricipital line. (b) CdCr view of the humerus of 28 kg mixed-breed dog. The dog is in dorsal recumbency with the limb extended cranially alongside the neck. The arrow shows the deltoid tuberosity and the arrowhead shows the area of the teres minor attachment. (c) CrCd view of the humerus with the dog lying in dorsal recumbency and the limb extended caudally alongside the thoracic wall. (d) CrCd view of the humerus with the dog in sternal recumbency. (e) Cranioproximal–craniodistal (skyline) view of the left shoulder joint showing the cranioproximal extremity of the humeral diaphysis, profiling the tubercles and the intertubercular or bicipital groove (arrowed) medial to the greater tubercle (arrowhead). © 2016 British Small Animal Veterinary Association

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9.4 (a) ML view of the normal humerus of a Boxer. The arrow indicates the tricipital line. (b) CdCr view of the humerus of 28 kg mixed-breed dog. The dog is in dorsal recumbency with the limb extended cranially alongside the neck. The arrow shows the deltoid tuberosity and the arrowhead shows the area of the teres minor attachment. (c) CrCd view of the humerus with the dog lying in dorsal recumbency and the limb extended caudally alongside the thoracic wall. (d) CrCd view of the humerus with the dog in sternal recumbency. (e) Cranioproximal–craniodistal (skyline) view of the left shoulder joint showing the cranioproximal extremity of the humeral diaphysis, profiling the tubercles and the intertubercular or bicipital groove (arrowed) medial to the greater tubercle (arrowhead).

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9.5

(a) ML and (b) CrCd views of the radius and ulna of a Labrador Retriever. The radiolucent area in the distolateral aspect of the radial diaphysis (arrowed) is a composite shadow caused by superimposition of the flexor carpi ulnaris tendon which attaches to the accessory carpal bone. This results in a reduced opacity medial to the tendon band. This area should not be mistaken for an abnormality. © 2016 British Small Animal Veterinary Association

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9.5 (a) ML and (b) CrCd views of the radius and ulna of a Labrador Retriever. The radiolucent area in the distolateral aspect of the radial diaphysis (arrowed) is a composite shadow caused by superimposition of the flexor carpi ulnaris tendon which attaches to the accessory carpal bone. This results in a reduced opacity medial to the tendon band. This area should not be mistaken for an abnormality.

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9.6

(a) ML and (b) CrCd views of the right femur of a 4-year-old cross-breed dog. The left femur has been drawn cranially along the body wall for the ML view, to avoid superimposition with the right limb. © 2016 British Small Animal Veterinary Association

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9.6 (a) ML and (b) CrCd views of the right femur of a 4-year-old cross-breed dog. The left femur has been drawn cranially along the body wall for the ML view, to avoid superimposition with the right limb.

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9.7

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9.7 (a) ML and (b) CrCd views of the tibia and fibula of a Labrador Retriever.

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9.8

CrCd view of the distal radius of a 14-month-old Labrador Retriever. The radiopaque horizontal linear band is a physeal scar at the site of the physis of the distal radius (arrowed). © 2016 British Small Animal Veterinary Association

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9.8 CrCd view of the distal radius of a 14-month-old Labrador Retriever. The radiopaque horizontal linear band is a physeal scar at the site of the physis of the distal radius (arrowed).

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9.9

(a) ML view of the distal humerus and proximal radius of a dog. Nutrient foramina are often visible along the mid-caudal cortices of long bones (black arrows on humerus and radius). Occasionally they are visible superimposed on the medullary cavity (white arrow). There is a Mach line (arrowhead) visible due to superimposition of the ulna and radius. (b) ML view of the normal humerus of a dog showing the supratrochlear foramen (black arrow) and medial epicondyle (white arrow). The lateral supracondylar crest (white arrowheads) is evident and further distally the caudal aspect of the lateral epicondyle is also visible (black arrowhead). © 2016 British Small Animal Veterinary Association

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9.9 (a) ML view of the distal humerus and proximal radius of a dog. Nutrient foramina are often visible along the mid-caudal cortices of long bones (black arrows on humerus and radius). Occasionally they are visible superimposed on the medullary cavity (white arrow). There is a Mach line (arrowhead) visible due to superimposition of the ulna and radius. (b) ML view of the normal humerus of a dog showing the supratrochlear foramen (black arrow) and medial epicondyle (white arrow). The lateral supracondylar crest (white arrowheads) is evident and further distally the caudal aspect of the lateral epicondyle is also visible (black arrowhead).

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9.10

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9.10 (a) ML and (b) CrCd views of the normal humerus of a 4-year-old cat. The arrows indicate the prominent supracondylar foramen.

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9.11

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9.11 CrCd view of the distal left radius and ulna of a dog with the normal lateral styloid process of the distal ulna identified (arrowed).

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9.12

(a) ML and (b) CrCd views of a normal feline radius and ulna. The lateral styloid process is indicated by the arrows. The square-shaped olecranon is indicated by an arrowhead. © 2016 British Small Animal Veterinary Association

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9.12 (a) ML and (b) CrCd views of a normal feline radius and ulna. The lateral styloid process is indicated by the arrows. The square-shaped olecranon is indicated by an arrowhead.

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9.13

(a) CrCd view of the proximal femur. The arrowhead indicates the lesser trochanter (trochanter minor), and black arrows show the outline of the greater trochanter (trochanter major). The trochanteric fossa (white arrow) is a radiolucent area located medial to the greater trochanter. (b) ML view of the distal femoral condyles of a dog, illustrating the radiopaque lines caused by the intercondylar fossa (white arrow). Note the prominence on the caudodistal femoral diaphysis (black arrow) associated with the attachment of the gastrocnemius muscle. The extensor fossa is visible (arrowhead). © 2016 British Small Animal Veterinary Association

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9.13 (a) CrCd view of the proximal femur. The arrowhead indicates the lesser trochanter (trochanter minor), and black arrows show the outline of the greater trochanter (trochanter major). The trochanteric fossa (white arrow) is a radiolucent area located medial to the greater trochanter. (b) ML view of the distal femoral condyles of a dog, illustrating the radiopaque lines caused by the intercondylar fossa (white arrow). Note the prominence on the caudodistal femoral diaphysis (black arrow) associated with the attachment of the gastrocnemius muscle. The extensor fossa is visible (arrowhead).

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9.14

(a) ML view of the normal proximal tibia of a dog. The arrowhead illustrates the normal position of the popliteal sesamoid. The fabellae are located at the caudodistal aspect of the femur (arrowed). (b) CrCd view of a normal distal femur of a dog with the patella (arrowed) and fabellae (arrowheads) clearly visible. (c) CrCd view of the stifle of a 6-year-old West Highland White Terrier: the medial fabella (arrowhead) is displaced distally when compared with the lateral fabellae (arrowed). This was a bilateral incidental finding. (d) CrCd view of the stifle of a 7-year-old Miniature Schnauzer showing fabellae of different sizes. The medial fabella (arrowhead) is smaller and is displaced distally when compared with the lateral fabella (arrowed). This was a bilateral incidental finding. (e) ML and (f) CrCd views of the stifle joint of an adult Jack Russell Terrier with a multipartite lateral fabella (arrowhead). This was a bilateral incidental finding. The patella is medially displaced and superimposed on the medial fabella (arrowed). © 2016 British Small Animal Veterinary Association

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9.14 (a) ML view of the normal proximal tibia of a dog. The arrowhead illustrates the normal position of the popliteal sesamoid. The fabellae are located at the caudodistal aspect of the femur (arrowed). (b) CrCd view of a normal distal femur of a dog with the patella (arrowed) and fabellae (arrowheads) clearly visible. (c) CrCd view of the stifle of a 6-year-old West Highland White Terrier: the medial fabella (arrowhead) is displaced distally when compared with the lateral fabellae (arrowed). This was a bilateral incidental finding. (d) CrCd view of the stifle of a 7-year-old Miniature Schnauzer showing fabellae of different sizes. The medial fabella (arrowhead) is smaller and is displaced distally when compared with the lateral fabella (arrowed). This was a bilateral incidental finding. (e) ML and (f) CrCd views of the stifle joint of an adult Jack Russell Terrier with a multipartite lateral fabella (arrowhead). This was a bilateral incidental finding. The patella is medially displaced and superimposed on the medial fabella (arrowed).

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9.15

(a) ML view of the normal femur of a 4-year-old cat. The other femur had been amputated 1 year previously. (b) CrCd view of the stifle of a 15-month-old cat. Note the differently sized fabellae and the visible growth plates. (c) CrCd view of the stifle of a cat that had only one fabella in this joint (arrowed). © 2016 British Small Animal Veterinary Association

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9.15 (a) ML view of the normal femur of a 4-year-old cat. The other femur had been amputated 1 year previously. (b) CrCd view of the stifle of a 15-month-old cat. Note the differently sized fabellae and the visible growth plates. (c) CrCd view of the stifle of a cat that had only one fabella in this joint (arrowed).

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9.16

(a) ML view of the normal tibia and fibula of a 6-year-old Bichon Frise. Note the prominent tibial plateau. (b) CrCd view of the tibia and fibula of a 5-year-old Staffordshire Bull Terrier. (c) ML and (d) CrCd views of the limb of a normal adult Greyhound. The tibial curvature is more marked than in (a) and (b). A blood pressure cuff encircles the distal tibia. (e) ML view of the tibia of a 5-year-old Boxer. There is a radiolucent circular area (arrowed) in the proximocranial tibia. This is an anatomical variant and should not be mistaken for pathology. © 2016 British Small Animal Veterinary Association

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9.16 (a) ML view of the normal tibia and fibula of a 6-year-old Bichon Frise. Note the prominent tibial plateau. (b) CrCd view of the tibia and fibula of a 5-year-old Staffordshire Bull Terrier. (c) ML and (d) CrCd views of the limb of a normal adult Greyhound. The tibial curvature is more marked than in (a) and (b). A blood pressure cuff encircles the distal tibia. (e) ML view of the tibia of a 5-year-old Boxer. There is a radiolucent circular area (arrowed) in the proximocranial tibia. This is an anatomical variant and should not be mistaken for pathology.

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9.17

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9.17 (a) ML and (b) CrCd views of the normal tibia and fibula of a 15-month-old cat. Note that some growth plates are still open.

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9.18

(a) ML and (b) CdCr views of the humerus of an adult Bassett Hound. (c) CrCd and (d) ML views of the left radius and ulna of a 9-year-old Basset Hound. (e) CrCd view of the femur of a chondrodystrophic mixed-breed terrier. (f) ML view of the humerus of a Jack Russell Terrier showing some chondrodystrophic features. Note the widened proximal metaphysis and curved diaphysis when compared with Figure 9.4a . © 2016 British Small Animal Veterinary Association

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9.18 (a) ML and (b) CdCr views of the humerus of an adult Bassett Hound. (c) CrCd and (d) ML views of the left radius and ulna of a 9-year-old Basset Hound. (e) CrCd view of the femur of a chondrodystrophic mixed-breed terrier. (f) ML view of the humerus of a Jack Russell Terrier showing some chondrodystrophic features. Note the widened proximal metaphysis and curved diaphysis when compared with Figure 9.4a .

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9.19

(a) CrCd view of the antebrachium showing fractures of the radius and ulna of a mixed-breed dog. The ulnar fracture is barely visible. (b) The ML view shows both fractures clearly (arrowed and arrowhead). This case shows the necessity of taking two orthogonal views and that the adjacent joints should also be included. (c) ML and (d) CrCd views of the humerus and shoulder of a 4-year-old cross-breed terrier dog that was involved in a road traffic accident. The ML view shows a supracondylar fracture of the distal diaphysis; the CrCd view shows an additional intercondylar fracture with distomedial displacement of the medial condylar fragment. This case indicates the importance of taking two orthogonal views because the severity of the fracture is not appreciated fully on the ML view. The circular ring effect seen on the CrCd view is due to inadequate extension of the limb, resulting in part of the humeral diaphysis lying parallel, rather than perpendicular, to the X-ray beam. (e) ML and (f) CrCd radiographs of a 3-year-old cat which was non-weight-bearing on its right thoracic limb. There is a comminuted fracture of the humeral diaphysis. The radiopaque fragmented metallic remnants of a bullet are visible in the soft tissues. Note that the proximal humeral physis is still visible. © 2016 British Small Animal Veterinary Association

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9.19 (a) CrCd view of the antebrachium showing fractures of the radius and ulna of a mixed-breed dog. The ulnar fracture is barely visible. (b) The ML view shows both fractures clearly (arrowed and arrowhead). This case shows the necessity of taking two orthogonal views and that the adjacent joints should also be included. (c) ML and (d) CrCd views of the humerus and shoulder of a 4-year-old cross-breed terrier dog that was involved in a road traffic accident. The ML view shows a supracondylar fracture of the distal diaphysis; the CrCd view shows an additional intercondylar fracture with distomedial displacement of the medial condylar fragment. This case indicates the importance of taking two orthogonal views because the severity of the fracture is not appreciated fully on the ML view. The circular ring effect seen on the CrCd view is due to inadequate extension of the limb, resulting in part of the humeral diaphysis lying parallel, rather than perpendicular, to the X-ray beam. (e) ML and (f) CrCd radiographs of a 3-year-old cat which was non-weight-bearing on its right thoracic limb. There is a comminuted fracture of the humeral diaphysis. The radiopaque fragmented metallic remnants of a bullet are visible in the soft tissues. Note that the proximal humeral physis is still visible.

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9.20

Lateral scintigrams of the pelvic limb of a 2-year-old Greyhound which was lame after a race. The bone scan shows (a) the normal right tibia and (b) a focal area of increased uptake (arrowed) of radiopharmaceutical (99mTc–MDP) in the distal third of the left tibial diaphysis. This was due to a stress fracture. © 2016 British Small Animal Veterinary Association

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9.20 Lateral scintigrams of the pelvic limb of a 2-year-old Greyhound which was lame after a race. The bone scan shows (a) the normal right tibia and (b) a focal area of increased uptake (arrowed) of radiopharmaceutical (99mTc–MDP) in the distal third of the left tibial diaphysis. This was due to a stress fracture.

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9.21

This 6-year-old Springer Spaniel was lame for 3 weeks on the left thoracic limb with pain elicited from the elbow joint. The CT study in a bone window of both elbows showed incomplete fissures (arrowed) in the caudal aspects of the left (a and b) and the right (c and d) humeral condyles. The dorsal plane images (b and d) show that the fissures are articular and run vertically and completely through the caudal aspects of the humeral condyles. There is sclerosis of the humeral condyles on each side of the fissures. Bilateral fissures are common in spaniels and both limbs should be examined. © 2016 British Small Animal Veterinary Association

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9.21 This 6-year-old Springer Spaniel was lame for 3 weeks on the left thoracic limb with pain elicited from the elbow joint. The CT study in a bone window of both elbows showed incomplete fissures (arrowed) in the caudal aspects of the left (a and b) and the right (c and d) humeral condyles. The dorsal plane images (b and d) show that the fissures are articular and run vertically and completely through the caudal aspects of the humeral condyles. There is sclerosis of the humeral condyles on each side of the fissures. Bilateral fissures are common in spaniels and both limbs should be examined.

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9.22

(a) ML view of the humerus of a 12-year-old Boxer that had jumped from a chair 12 hours before. There is a long spiral fracture of the mid-humeral diaphysis. A focal area of lysis is visible (arrowed). This proved to be a pathological fracture secondary to a haemangiosarcoma. (b) ML view of the right humerus of an 11-year-old Golden Retriever that had become acutely lame 3 days previously while chasing a rabbit. There is an oblique fracture through the junction of the proximal and middle thirds of the humeral diaphysis. A subtle radiolucent area is visible (arrowed), with thinning of the cranial cortex (arrowhead). This was a pathological fracture secondary to a bone sarcoma. © 2016 British Small Animal Veterinary Association

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9.22 (a) ML view of the humerus of a 12-year-old Boxer that had jumped from a chair 12 hours before. There is a long spiral fracture of the mid-humeral diaphysis. A focal area of lysis is visible (arrowed). This proved to be a pathological fracture secondary to a haemangiosarcoma. (b) ML view of the right humerus of an 11-year-old Golden Retriever that had become acutely lame 3 days previously while chasing a rabbit. There is an oblique fracture through the junction of the proximal and middle thirds of the humeral diaphysis. A subtle radiolucent area is visible (arrowed), with thinning of the cranial cortex (arrowhead). This was a pathological fracture secondary to a bone sarcoma.

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9.23

CrCd views (a–b) of the tibia and fibula of a 5-year-old Collie involved in a road traffic accident. Surgical implants were used to stabilize the fractures. (a) Radiograph taken 10 weeks post surgery. There was a small triangular isolated bone fragment (arrowed) seen at the centre of the fracture site that reflects delayed fracture healing. This fragment has a normal mineral opacity, which differentiates it from a sequestrum. (b) Eight weeks later the fragment has been incorporated into the callus. (c) ML and (d) CrCd views of the right antebrachium of a 2-year-old Toy Poodle taken 6 weeks after injury. There is a malalignment of the fracture ends with rounded radial fracture margins visible on the ML view. This is a malunion fracture. (e) ML and (f) CrCd views of the antebrachium of a 2-year-old Collie that had been injured 10 weeks previously and an external cast applied to the limb. The distal radial and ulnar fracture fragments have displaced cranially, medially and proximally in relation to the proximal fragments. Callus formation is bridging the distal ulnar fragment to the proximal radial fragment, resulting in malalignment and significant limb shortening with malunion taking place. This case illustrates the importance of two orthogonal views: the severity of the displacement is only appreciated on the lateral view. (g) ML view of the left radius and ulna of an adult cross-breed Labrador Retriever with an unknown clinical history. The distal two thirds of the radius and the ulnar diaphyses have united in the callus remodelling of an old fracture and formed a synostosis. © 2016 British Small Animal Veterinary Association

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9.23 CrCd views (a–b) of the tibia and fibula of a 5-year-old Collie involved in a road traffic accident. Surgical implants were used to stabilize the fractures. (a) Radiograph taken 10 weeks post surgery. There was a small triangular isolated bone fragment (arrowed) seen at the centre of the fracture site that reflects delayed fracture healing. This fragment has a normal mineral opacity, which differentiates it from a sequestrum. (b) Eight weeks later the fragment has been incorporated into the callus. (c) ML and (d) CrCd views of the right antebrachium of a 2-year-old Toy Poodle taken 6 weeks after injury. There is a malalignment of the fracture ends with rounded radial fracture margins visible on the ML view. This is a malunion fracture. (e) ML and (f) CrCd views of the antebrachium of a 2-year-old Collie that had been injured 10 weeks previously and an external cast applied to the limb. The distal radial and ulnar fracture fragments have displaced cranially, medially and proximally in relation to the proximal fragments. Callus formation is bridging the distal ulnar fragment to the proximal radial fragment, resulting in malalignment and significant limb shortening with malunion taking place. This case illustrates the importance of two orthogonal views: the severity of the displacement is only appreciated on the lateral view. (g) ML view of the left radius and ulna of an adult cross-breed Labrador Retriever with an unknown clinical history. The distal two thirds of the radius and the ulnar diaphyses have united in the callus remodelling of an old fracture and formed a synostosis.

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9.24

(a) ML view of the right elbow of a patient with coccidioidomycosis. Extensive and aggressive new bone formation is evident affecting the distal third of the humeral diaphysis. (b) ML view of the right stifle joint of a patient with blastomycosis. There is marked lysis (arrowheads) of the cranioproximal tibial diaphysis with a pathological avulsion fracture fragment (arrowed) of the cranial aspect of the tibial plateau and intra-articular soft tissue swelling. (c) ML view of the distal tibia, fibula and tarsus of a 3-year-old Staffordshire Bull Terrier with a history of right pelvic limb swelling, pyrexia, lymphadenopathy and gastrointestinal signs. There is focal osteolysis in the distal tibial metaphysis adjacent to the joint and in the plantarodistal aspect of the calcaneus (arrowed). Subsequent fungal culture from a bone aspirate yielded Byssochlamys spp., which had developed secondary to ciclosporin therapy. The infection resolved over a 6-month period with antifungal treatment. (b, Courtesy of RD Pechman) © 2016 British Small Animal Veterinary Association

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9.24 (a) ML view of the right elbow of a patient with coccidioidomycosis. Extensive and aggressive new bone formation is evident affecting the distal third of the humeral diaphysis. (b) ML view of the right stifle joint of a patient with blastomycosis. There is marked lysis (arrowheads) of the cranioproximal tibial diaphysis with a pathological avulsion fracture fragment (arrowed) of the cranial aspect of the tibial plateau and intra-articular soft tissue swelling. (c) ML view of the distal tibia, fibula and tarsus of a 3-year-old Staffordshire Bull Terrier with a history of right pelvic limb swelling, pyrexia, lymphadenopathy and gastrointestinal signs. There is focal osteolysis in the distal tibial metaphysis adjacent to the joint and in the plantarodistal aspect of the calcaneus (arrowed). Subsequent fungal culture from a bone aspirate yielded Byssochlamys spp., which had developed secondary to ciclosporin therapy. The infection resolved over a 6-month period with antifungal treatment. (b, Courtesy of RD Pechman)

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9.25

ML view of a stifle of a dog with stippled focal lysis in the cranioproximal tibial diaphysis (arrowheads) and no joint involvement. This was due to leishmaniosis. (Reproduced from Agut et al. (2003) with permission from Veterinary Record) © 2016 British Small Animal Veterinary Association

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9.25 ML view of a stifle of a dog with stippled focal lysis in the cranioproximal tibial diaphysis (arrowheads) and no joint involvement. This was due to leishmaniosis. (Reproduced from Agut et al. (2003) with permission from Veterinary Record)

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9.26

(a) ML and (b) CdCr views of the humerus of a Jack Russell Terrier that developed soft tissue swelling at the site of a dog bite. A moderately aggressive periosteal reaction (arrowheads) affecting the distal humerus is present, secondary to osteomyelitis. © 2016 British Small Animal Veterinary Association

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9.26 (a) ML and (b) CdCr views of the humerus of a Jack Russell Terrier that developed soft tissue swelling at the site of a dog bite. A moderately aggressive periosteal reaction (arrowheads) affecting the distal humerus is present, secondary to osteomyelitis.

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9.27

(a) ML view of the antebrachium of a cat that had a discharging sinus over the lateral aspect of the distal thoracic limb following a cat bite. A sequestrum (arrowed) is present in the distal ulna. (b) ML view of a humeral fracture in a dog which was repaired using an intramedullary pin, showing excessive exuberant callus formation. In the centre of the fracture site is a linear radiopaque fragment (arrowed), which is a bone sequestrum. © 2016 British Small Animal Veterinary Association

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9.27 (a) ML view of the antebrachium of a cat that had a discharging sinus over the lateral aspect of the distal thoracic limb following a cat bite. A sequestrum (arrowed) is present in the distal ulna. (b) ML view of a humeral fracture in a dog which was repaired using an intramedullary pin, showing excessive exuberant callus formation. In the centre of the fracture site is a linear radiopaque fragment (arrowed), which is a bone sequestrum.

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9.28

(a) CrCd and (b) ML views of the limb of a 2-year-old Boxer that presented with a swelling on the medial aspect of the distal radius due to an osteochondroma. On the CrCd view there is a bony prominence (arrowheads) extending medially on the distomedial aspect of the radial metaphysis. On the ML view it is superimposed on the distal ulna (arrowheads). © 2016 British Small Animal Veterinary Association

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9.28 (a) CrCd and (b) ML views of the limb of a 2-year-old Boxer that presented with a swelling on the medial aspect of the distal radius due to an osteochondroma. On the CrCd view there is a bony prominence (arrowheads) extending medially on the distomedial aspect of the radial metaphysis. On the ML view it is superimposed on the distal ulna (arrowheads).

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9.29

A longitudinal ultrasonographic image of the proximocranial humerus illustrating the guidance of a needle (arrowed) into a neoplastic bone defect (arrowhead). The horizontal hyperechoic bone margin is irregular as a result of periosteal reaction (proximal is to the left of the image). © 2016 British Small Animal Veterinary Association

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9.29 A longitudinal ultrasonographic image of the proximocranial humerus illustrating the guidance of a needle (arrowed) into a neoplastic bone defect (arrowhead). The horizontal hyperechoic bone margin is irregular as a result of periosteal reaction (proximal is to the left of the image).

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9.30

Examples of osteosarcoma. (a) ML view of the distal tibia of a mixed-breed dog. There is an aggressive periosteal reaction, osteolysis, mineralization of the soft tissues, a poorly defined zone of transition in the distal third of the tibial diaphysis and an extensive encircling soft tissue swelling. This is termed a ‘sunburst’ reaction. (b) ML view of the shoulder of a 10-year-old Rottweiler which had been lame for 3 months. There is complete destruction of the proximal third of the humerus with faint mineralization in the adjacent soft tissues (arrowheads). (c) CrCd view of the distal radius of a 5-year-old St Bernard with a swollen distal limb. There is a spiculated periosteal reaction (arrowed) on the distomedial aspect of the radius with localized soft tissue swelling medially. (d) ML view of the proximal tibia of an 8-year-old Rottweiler. There is focal lysis of the proximocaudal tibia with adjacent active periosteal reaction. (e) ML view of the stifle of a 9-year-old spaniel cross-breed. There is a subtle change in the trabecular pattern of the cranioproximal tibia (arrowed) with pinpoint areas of osteolysis and sclerosis. (f) ML and (g) CrCd views of a 7-year-old pointer cross-breed with a proliferative sclerotic bone reaction (arrowed) in the proximocranial and proximolateral radius. This was a chondroblastic osteosarcoma. Incidental moderate elbow arthrosis is present. (h) ML view of the radius and ulna showing an expansile septated osteolytic lesion affecting the mid-diaphysis of the ulna. This is an unusual site for an osteosarcoma. (i) Sagittal reconstruction of a CT series, displayed using a bone window, from the dog shown in (h). The distal extension of the expansile neoplasm into the medullary cavity is clearly seen. (j) A T2W MRI study (dorsal plane) of the distal radius of a dog with an osteosarcoma. The destructive lesion (arrowhead) can be seen in the distal radius. It extends proximally into the medullary cavity. There is invasion into the adjacent soft tissue structures. The normal hyperintense medullary cavity is visible (arrowed). (j, Courtesy of RD Pechman) © 2016 British Small Animal Veterinary Association

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9.30 Examples of osteosarcoma. (a) ML view of the distal tibia of a mixed-breed dog. There is an aggressive periosteal reaction, osteolysis, mineralization of the soft tissues, a poorly defined zone of transition in the distal third of the tibial diaphysis and an extensive encircling soft tissue swelling. This is termed a ‘sunburst’ reaction. (b) ML view of the shoulder of a 10-year-old Rottweiler which had been lame for 3 months. There is complete destruction of the proximal third of the humerus with faint mineralization in the adjacent soft tissues (arrowheads). (c) CrCd view of the distal radius of a 5-year-old St Bernard with a swollen distal limb. There is a spiculated periosteal reaction (arrowed) on the distomedial aspect of the radius with localized soft tissue swelling medially. (d) ML view of the proximal tibia of an 8-year-old Rottweiler. There is focal lysis of the proximocaudal tibia with adjacent active periosteal reaction. (e) ML view of the stifle of a 9-year-old spaniel cross-breed. There is a subtle change in the trabecular pattern of the cranioproximal tibia (arrowed) with pinpoint areas of osteolysis and sclerosis. (f) ML and (g) CrCd views of a 7-year-old pointer cross-breed with a proliferative sclerotic bone reaction (arrowed) in the proximocranial and proximolateral radius. This was a chondroblastic osteosarcoma. Incidental moderate elbow arthrosis is present. (h) ML view of the radius and ulna showing an expansile septated osteolytic lesion affecting the mid-diaphysis of the ulna. This is an unusual site for an osteosarcoma. (i) Sagittal reconstruction of a CT series, displayed using a bone window, from the dog shown in (h). The distal extension of the expansile neoplasm into the medullary cavity is clearly seen. (j) A T2W MRI study (dorsal plane) of the distal radius of a dog with an osteosarcoma. The destructive lesion (arrowhead) can be seen in the distal radius. It extends proximally into the medullary cavity. There is invasion into the adjacent soft tissue structures. The normal hyperintense medullary cavity is visible (arrowed). (j, Courtesy of RD Pechman)

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Examples of fibrosarcoma. (a) CrCd view of the distal antebrachium of an adult Boxer that presented with a sudden history of acute lameness. Moth-eaten osteolysis is present in the distal aspect of the radial diaphysis. A faint vertical radiolucent pathological fracture line is also present (arrowed). (b) ML and (c) CrCd views of the stifle of an adult dog. This case illustrates the more productive features that can be associated with fibrosarcoma. New bone formation encircles the proximal tibia (arrowheads). © 2016 British Small Animal Veterinary Association

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9.31 Examples of fibrosarcoma. (a) CrCd view of the distal antebrachium of an adult Boxer that presented with a sudden history of acute lameness. Moth-eaten osteolysis is present in the distal aspect of the radial diaphysis. A faint vertical radiolucent pathological fracture line is also present (arrowed). (b) ML and (c) CrCd views of the stifle of an adult dog. This case illustrates the more productive features that can be associated with fibrosarcoma. New bone formation encircles the proximal tibia (arrowheads).

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9.32

CrCd view of the distal radius and ulna of a cross-breed dog with a haemangiosarcoma. There is a radiolucent expansile lesion in the distal ulna which has disrupted the cortical margin (big arrow). A smooth periosteal reaction is seen proximally (tiny arrow), and distally the cortical bone is thinned (arrowhead). © 2016 British Small Animal Veterinary Association

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9.32 CrCd view of the distal radius and ulna of a cross-breed dog with a haemangiosarcoma. There is a radiolucent expansile lesion in the distal ulna which has disrupted the cortical margin (big arrow). A smooth periosteal reaction is seen proximally (tiny arrow), and distally the cortical bone is thinned (arrowhead).

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9.33

Multiple myeloma. (a) ML view of the tibia of a 10-year-old Boxer showing multiple pinpoint radiolucent foci (arrowed) scattered throughout the proximal two-thirds of the medullary cavity. (b) VD view of the pelvis of a retriever. Discrete, well circumscribed areas of osteolysis (arrowed) are seen in the femoral head and greater trochanter. © 2016 British Small Animal Veterinary Association

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9.33 Multiple myeloma. (a) ML view of the tibia of a 10-year-old Boxer showing multiple pinpoint radiolucent foci (arrowed) scattered throughout the proximal two-thirds of the medullary cavity. (b) VD view of the pelvis of a retriever. Discrete, well circumscribed areas of osteolysis (arrowed) are seen in the femoral head and greater trochanter.

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9.34

CT images in a bone window of a 10-year-old Collie with lameness and a swollen left thigh region. (a) Transverse (right and left pelvic limbs) and (b) sagittal reconstruction show a large 10 × 8 cm well marginated fat-attenuating mass (arrowheads) interposed between the semimembranosus and semitendinosus muscles and extending proximally and caudal to the ischium. The fat mass extends to but apparently does not involve the cortical bone of the femur. CT aids surgical planning. This was a lipoma. © 2016 British Small Animal Veterinary Association

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9.34 CT images in a bone window of a 10-year-old Collie with lameness and a swollen left thigh region. (a) Transverse (right and left pelvic limbs) and (b) sagittal reconstruction show a large 10 × 8 cm well marginated fat-attenuating mass (arrowheads) interposed between the semimembranosus and semitendinosus muscles and extending proximally and caudal to the ischium. The fat mass extends to but apparently does not involve the cortical bone of the femur. CT aids surgical planning. This was a lipoma.

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9.35

CrCd view of the stifle of a small-breed dog. Osteolytic ‘moth-eaten’ areas are seen in the medullary cavities of the distal femur and proximal tibia. There is a wide transition zone and an aggressive periosteal reaction on the distomedial femoral cortex. These changes were due to a primary prostatic adenocarcinoma that underwent metastasis to the stifle. © 2016 British Small Animal Veterinary Association

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9.35 CrCd view of the stifle of a small-breed dog. Osteolytic ‘moth-eaten’ areas are seen in the medullary cavities of the distal femur and proximal tibia. There is a wide transition zone and an aggressive periosteal reaction on the distomedial femoral cortex. These changes were due to a primary prostatic adenocarcinoma that underwent metastasis to the stifle.

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9.36

A series of images obtained over a 3-year period from a 7-year-old (at initial presentation) Labrador Retriever cross-breed which presented with a hard swelling on the mid-tibial diaphysis that underwent malignant transformation over the 3-year period. (a) ML view of the tibia and fibula showing a discrete well marginated osteolytic area (arrowhead) surrounded by a collar of endosteal and smooth periosteal new bone formation along the cortex (arrowed). (b) The ML view obtained 3 months later, following aspiration (which indicated necrosis) and subsequent curettage and antimicrobial therapy, shows that the lesion is more quiescent and organized (arrowheads). (c) ML view obtained 2 years later shows that the lesion has changed into a lobulated, well marginated mixed radiolucent granular area (arrowheads). (d) CT sagittal reconstruction in a bone window, made at the same time as the image in (c), shows that the lobulated lesion (black arrow) is well demarcated cranially (arrowhead) but extends into the medullary cavity (white arrow). A bone biopsy revealed necrotic tissue, and surgical curettage was repeated. (e) One year later and 3 years after the initial presentation, another CT was performed. This sagittal reconstruction CT image in a bone window shows that the lesion has become aggressive and expands proximally and distally. Histopathology indicated that it was an aberrant fibrosarcoma. © 2016 British Small Animal Veterinary Association

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9.36 A series of images obtained over a 3-year period from a 7-year-old (at initial presentation) Labrador Retriever cross-breed which presented with a hard swelling on the mid-tibial diaphysis that underwent malignant transformation over the 3-year period. (a) ML view of the tibia and fibula showing a discrete well marginated osteolytic area (arrowhead) surrounded by a collar of endosteal and smooth periosteal new bone formation along the cortex (arrowed). (b) The ML view obtained 3 months later, following aspiration (which indicated necrosis) and subsequent curettage and antimicrobial therapy, shows that the lesion is more quiescent and organized (arrowheads). (c) ML view obtained 2 years later shows that the lesion has changed into a lobulated, well marginated mixed radiolucent granular area (arrowheads). (d) CT sagittal reconstruction in a bone window, made at the same time as the image in (c), shows that the lobulated lesion (black arrow) is well demarcated cranially (arrowhead) but extends into the medullary cavity (white arrow). A bone biopsy revealed necrotic tissue, and surgical curettage was repeated. (e) One year later and 3 years after the initial presentation, another CT was performed. This sagittal reconstruction CT image in a bone window shows that the lesion has become aggressive and expands proximally and distally. Histopathology indicated that it was an aberrant fibrosarcoma.

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9.37

Examples of malignant transformation. (a) ML view of the humerus of an adult dog that had a mid-diaphyseal humeral fracture repaired. The implant was removed 6 months postoperatively. Three years later, the dog presented acutely lame. There is a pathological fracture through the mid-diaphyseal region (black arrow), with a mottled radiopacity and an aggressive periosteal reaction (white arrows). A separated fragment is visible distocranially to a large radiolucent cavity (arrowhead) resulting from a pathological fracture (double arrowheads). (b) ML and (c) CrCd radiographs of the right femur of a 10-year-old Boxer that had a surgical repair for a femoral fracture 7 years previously and presented acutely lame for 4 weeks. There is marked osteolysis within the distal medullary cavity (arrowed). This was a malignant osteoblastic osteosarcoma and may be a coincidental development but malignant transformation is likely. © 2016 British Small Animal Veterinary Association

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9.37 Examples of malignant transformation. (a) ML view of the humerus of an adult dog that had a mid-diaphyseal humeral fracture repaired. The implant was removed 6 months postoperatively. Three years later, the dog presented acutely lame. There is a pathological fracture through the mid-diaphyseal region (black arrow), with a mottled radiopacity and an aggressive periosteal reaction (white arrows). A separated fragment is visible distocranially to a large radiolucent cavity (arrowhead) resulting from a pathological fracture (double arrowheads). (b) ML and (c) CrCd radiographs of the right femur of a 10-year-old Boxer that had a surgical repair for a femoral fracture 7 years previously and presented acutely lame for 4 weeks. There is marked osteolysis within the distal medullary cavity (arrowed). This was a malignant osteoblastic osteosarcoma and may be a coincidental development but malignant transformation is likely.

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9.39

(a) ML and (b) CrCd views of the left femur of a 13-year-old cat which was lame and had a large mass in the stifle region. There is a large productive lobulated mass of mixed osteolytic and sclerotic areas involving the distal femoral diaphysis. The margins are smooth and there is a large soft tissue swelling. This was a chondrosarcoma. © 2016 British Small Animal Veterinary Association

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9.39 (a) ML and (b) CrCd views of the left femur of a 13-year-old cat which was lame and had a large mass in the stifle region. There is a large productive lobulated mass of mixed osteolytic and sclerotic areas involving the distal femoral diaphysis. The margins are smooth and there is a large soft tissue swelling. This was a chondrosarcoma.

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9.40

(a) CdCr view of the left shoulder of a 13-year-old Collie with chronic thoracic limb lameness and localized pain in the proximolateral humerus. A proliferative non-aggressive bony exostosis is present at the site of attachment of the infraspinatus tendon (arrowed). (b) Longtitudinal ultrasonogram of the area in (a) shows the hyperechoic infraspinatus tendon coursing horizontally from a proximal to distal direction (black arrow). At the site of attachment, the tendon is hypoechoic (arrowheads) and the underlying cortical bone is irregular and spiculated (white arrow). The diagnosis was strain of the infraspinatus tendon (proximal is to the left of the image). (c) Partial VD view of the pelvis of a 1-year-old Cocker Spaniel with a history of a left pelvic limb lameness for 6 weeks. There was pain on abduction of the femur and pain on manipulation of the proximomedial femoral diaphysis. This magnified view of the proximal femur shows a faint periosteal reaction along the proximomedial aspect of the femoral cortex (arrowheads). This is the site of attachment of the vastus medialis muscle. (d) ML view of the stifle of a 10-year-old Golden Retriever presented with a pelvic limb lameness of several months’ duration. Both fabellae of the gastrocnemius muscle are displaced distally. The lateral fabella (arrowed) is completely avulsed distally from its normal location caudal to the distal femur. The medial fabella (arrowhead) is only marginally displaced. Faint mineral opacities are visible caudal to the distal femoral diaphysis indicating the origin of the avulsion from the distal femur. (e) and (f) ML radiographs of the left and right elbows of a 2.5-year-old Leonberger that was undergoing an elbow dysplasia screening examination. The dog was not lame. The flexed ML views show modelling of the distal aspect of the medial epicondyles with mineralization distally in the adjacent soft tissues (arrowed). This is due to flexor enthesopathy. © 2016 British Small Animal Veterinary Association

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9.40 (a) CdCr view of the left shoulder of a 13-year-old Collie with chronic thoracic limb lameness and localized pain in the proximolateral humerus. A proliferative non-aggressive bony exostosis is present at the site of attachment of the infraspinatus tendon (arrowed). (b) Longtitudinal ultrasonogram of the area in (a) shows the hyperechoic infraspinatus tendon coursing horizontally from a proximal to distal direction (black arrow). At the site of attachment, the tendon is hypoechoic (arrowheads) and the underlying cortical bone is irregular and spiculated (white arrow). The diagnosis was strain of the infraspinatus tendon (proximal is to the left of the image). (c) Partial VD view of the pelvis of a 1-year-old Cocker Spaniel with a history of a left pelvic limb lameness for 6 weeks. There was pain on abduction of the femur and pain on manipulation of the proximomedial femoral diaphysis. This magnified view of the proximal femur shows a faint periosteal reaction along the proximomedial aspect of the femoral cortex (arrowheads). This is the site of attachment of the vastus medialis muscle. (d) ML view of the stifle of a 10-year-old Golden Retriever presented with a pelvic limb lameness of several months’ duration. Both fabellae of the gastrocnemius muscle are displaced distally. The lateral fabella (arrowed) is completely avulsed distally from its normal location caudal to the distal femur. The medial fabella (arrowhead) is only marginally displaced. Faint mineral opacities are visible caudal to the distal femoral diaphysis indicating the origin of the avulsion from the distal femur. (e) and (f) ML radiographs of the left and right elbows of a 2.5-year-old Leonberger that was undergoing an elbow dysplasia screening examination. The dog was not lame. The flexed ML views show modelling of the distal aspect of the medial epicondyles with mineralization distally in the adjacent soft tissues (arrowed). This is due to flexor enthesopathy.

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9.41

(a–c) ML views from three differently sized adult dogs showing examples of modelling (arrowed) in the vicinity of the interosseous ligament between the radius and ulna at the level of the nutrient foramen in the radius. These are usually incidental findings, as in these three cases. © 2016 British Small Animal Veterinary Association

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9.41 (a–c) ML views from three differently sized adult dogs showing examples of modelling (arrowed) in the vicinity of the interosseous ligament between the radius and ulna at the level of the nutrient foramen in the radius. These are usually incidental findings, as in these three cases.

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9.42

VD close-up view of the left coxofemoral joint with a triangular radiopacity (arrowed) in the femoral neck, indicative of an infarct. This dog had systemic lupus erythematosus. (Courtesy of C Gibbs) © 2016 British Small Animal Veterinary Association

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9.42 VD close-up view of the left coxofemoral joint with a triangular radiopacity (arrowed) in the femoral neck, indicative of an infarct. This dog had systemic lupus erythematosus. (Courtesy of C Gibbs)

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9.43

CrCd views of the left antebrachium of a 9-year-old German Shepherd Dog which presented with swollen limbs. (a) CrCd view showing an irregular brush border periosteal reaction throughout the radial and ulnar diaphyses (arrowed). (b) Magnified CrCd view showing an irregular palisading periosteal reaction (arrowed) along the distal radial and ulnar diaphyses. The dog had a primary lung carcinoma. © 2016 British Small Animal Veterinary Association

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9.43 CrCd views of the left antebrachium of a 9-year-old German Shepherd Dog which presented with swollen limbs. (a) CrCd view showing an irregular brush border periosteal reaction throughout the radial and ulnar diaphyses (arrowed). (b) Magnified CrCd view showing an irregular palisading periosteal reaction (arrowed) along the distal radial and ulnar diaphyses. The dog had a primary lung carcinoma.

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9.44

Examples of panosteitis. (a) ML view of the antebrachium of a 2-year-old German Shepherd Dog that presented with a shifting thoracic limb lameness. There are areas of increased radiopacity (arrowed) within the medullary cavity of the radius. (b) Sagittal CT reconstruction in a bone window showing increased opacity (arrowed) in the proximal ulna of a Newfoundland, compared with the dog’s normal limb (c). (d) VD view of the pelvis and femurs of a 3-year-old German Shepherd Dog with a shifting pelvic limb lameness. There is an increased radiopacity within the left mid-femoral diaphysis (arrowed) when compared with the right femur. A faint indistinct periosteal reaction is seen along the diaphyseal cortices (arrowheads). (b,c, Courtesy of Y Ruel) © 2016 British Small Animal Veterinary Association

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9.44 Examples of panosteitis. (a) ML view of the antebrachium of a 2-year-old German Shepherd Dog that presented with a shifting thoracic limb lameness. There are areas of increased radiopacity (arrowed) within the medullary cavity of the radius. (b) Sagittal CT reconstruction in a bone window showing increased opacity (arrowed) in the proximal ulna of a Newfoundland, compared with the dog’s normal limb (c). (d) VD view of the pelvis and femurs of a 3-year-old German Shepherd Dog with a shifting pelvic limb lameness. There is an increased radiopacity within the left mid-femoral diaphysis (arrowed) when compared with the right femur. A faint indistinct periosteal reaction is seen along the diaphyseal cortices (arrowheads). (b,c, Courtesy of Y Ruel)

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9.45

ML view of the humerus of a 14-month-old St Bernard. The radiopaque horizontal bands (arrowed) in the medullary cavity represent growth arrest or stress lines and are not clinically significant. © 2016 British Small Animal Veterinary Association

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9.45 ML view of the humerus of a 14-month-old St Bernard. The radiopaque horizontal bands (arrowed) in the medullary cavity represent growth arrest or stress lines and are not clinically significant.

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9.46

ML views of the tibia and radius and ulna of a 9-year-old Jack Russell Terrier with osteopetrosis of unknown aetiology. The cortices of (a) the tibia and (b) the radius and ulna are grossly thickened and only faint remnants of the medullary cavities are visible. This abnormality was present in all the limbs of this dog. © 2016 British Small Animal Veterinary Association

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9.46 ML views of the tibia and radius and ulna of a 9-year-old Jack Russell Terrier with osteopetrosis of unknown aetiology. The cortices of (a) the tibia and (b) the radius and ulna are grossly thickened and only faint remnants of the medullary cavities are visible. This abnormality was present in all the limbs of this dog.

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9.47

CrCd view of the distal antebrachium of a 2-year-old Toy Poodle that had external coaptation for fractures of the radius and ulna for a 10-week period. Note the overall decrease in radiopacity of the distal radial and ulnar fracture fragments and the distal limb. This is disuse osteopenia (the same case as 9.23cd). The linear streaks and mottled radiopacity around the limb and phalanges are due to wet hair and a rope tie, respectively. © 2016 British Small Animal Veterinary Association

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9.47 CrCd view of the distal antebrachium of a 2-year-old Toy Poodle that had external coaptation for fractures of the radius and ulna for a 10-week period. Note the overall decrease in radiopacity of the distal radial and ulnar fracture fragments and the distal limb. This is disuse osteopenia (the same case as 9.23cd). The linear streaks and mottled radiopacity around the limb and phalanges are due to wet hair and a rope tie, respectively.

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9.48

CrCd view of the distal antebrachium of an adult dog. An extensive osteolytic expansile mass has deformed the ulnar diaphysis. The cortices are thinned and there is a disruption on the lateral aspect of the ulna (arrowed). This was an aneurysmal bone cyst. (Courtesy of RD Pechman) © 2016 British Small Animal Veterinary Association

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9.48 CrCd view of the distal antebrachium of an adult dog. An extensive osteolytic expansile mass has deformed the ulnar diaphysis. The cortices are thinned and there is a disruption on the lateral aspect of the ulna (arrowed). This was an aneurysmal bone cyst. (Courtesy of RD Pechman)