My Puppy is Limping: What Do the X-Rays Show? William Tod Drost, DVM, DACVR Ohio State University Columbus, OH
Developmental abnormalities of the canine skeleton manifest in many ways. While fractures are common in young animals, they are not the focus of this presentation. The immature bone has multiple parts – epiphysis, physis, metaphysis and diaphysis. The physis, or growth plate, is soft tissue opacity and appears as a radiolucent zone at the ends of the bones. When growth plates are open, it appears that the number of bones has multiplied and this can be confusing. Radiographing the contralateral bone/joint is an excellent point of reference to help determine what is normal or abnormal. Additionally, many developmental diseases are often found bilaterally, so imaging the contralateral side helps determine the extent of the disease.
Osteochondrosis Failure of endochondral ossification
Osteochondritis dissecans Failure of endochondral ossification with a cartilage flap Signalment • Rapidly growing large breed dogs • 6-9 months old Common sites • Caudal humeral head • Medial humeral condyle • Femoral condyles • Trochlear ridges of the talus Radiographic signs • Flattening / concavity of bone surface • Apparent joint space widening • Cartilage flap • Only seen if mineralized o Arthrogram o MRI • Degenerative joint disease
Elbow dysplasia • Triad of elbow diseases o Ununited anconeal process o Medial humeral osteochondrosis o Fragmented medial coronoid process • Results in/from joint incongruity
Ununited anconeal process • Large breed dogs o German Shepherd dogs • No fusion of anconeal process after 150 days • Irregular, radiolucent line between anconeal process & proximal ulna • Flexed lateral radiograph best
Humeral condyle OCD • Concave radiolucent defect on medial humeral condyle o Craniocaudal projection
Fragmented medial coronoid process • Most common cause of elbow dysplasia • Medium to large breed dogs 1
• Rule out ununited anconeal process and OCD first o Usually do not see fragmented coronoid (CT useful) • Blunting of coronoid on lateral • Superimposed on radial head • Rounding of coronoid on CC view • Joint incongruity • Degenerative joint disease
Aseptic necrosis of femoral head Synonyms • Legg-Calvé-Perthes Disease • Avascular necrosis of femoral head Pathophysiology • Loss of blood supply to femoral head / epiphysis • Articular cartilage growth continues • Revascularization • Incomplete removal of necrotic bone • Invasion of granulation tissue Radiographic findings • Varies with duration • Linear lucencies – early • Flat, irregular epiphysis & metaphysis • Apparent joint space widening • Muscle atrophy & DJD
Panosteitis • Self-limiting bone disease • Signalment o Male:female :: 4:1 o German shepherd dogs o 5-12 months old • Radiographic Findings o Increased intramedullary bone opacity o Solitary o Multifocal o Often near nutrient foramen o ± smooth periosteal reaction
Hypertrophic osteodystrophy (HOD) • Large and giant breed dogs • 2-7 months • Systemic illness o Unknown cause o Possibly distemper virus o Fever, diarrhea, leukocytosis, anemia, pneumonia • Self-limiting • Radiographic Findings o Transverse, lucent lines in the metaphysis o “Double physis” sign o Irregular periosteal bone around metaphysis o ± Regional soft tissue swelling
Secondary hyperparathyroidism Nutritional • Calcium deficient or calcium/phosphorus imbalance
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Renal • Chronic renal disease leads to systemic calcium deficiency Radiographic findings • Decreased bone opacity • Generalized • Thin cortices • Prone to pathologic fractures
Patellar luxation • Medial o Small & toy breed dogs • Lateral o Large breed dogs • Displacement of patella medially or laterally • Angular limb deformities
Hip dysplasia • Abnormal development of coxofemoral joints • Typically bilateral o ~ 11% unilateral • Inherited disorder • Various radiographic signs o Degree of joint laxity o Duration of disease • Radiographic findings o Coxofemoral subluxation o < 50% of femoral head in acetabulum o Shallow acetabulum o Osteophytes . Acetabulum . Femoral neck o Thigh & gluteal muscle atrophy
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