Orthopedic Exam

Assessment Protocol: Observe walk/trot on hard surface; note weight distribution, stride length symmetry, pain response; repeat after exercise (fatigue may unmask mild lameness)

Cranial Cruciate Ligament (CCL) Assessment

Drawer Test (Anterior Drawer Sign)

• Position: Dog in lateral recumbency; examiner stabilizes femur above knee with one hand, applies gentle anterior pressure on proximal tibia below knee with other
• Positive test: Anterior tibial translation relative to femur (1-3 mm movement possible)
• Sensitivity/Specificity: 70-90% for CCL rupture depending on chronicity and observer experience
• Limitation: False negatives in partial tears or acute cases with protective muscle tone; false positives in excessive ligamentous laxity

Tibial Thrust (Cranial Tibial Thrust)

• Position: Dog standing or in lateral recumbency with knee flexed to 90°; examiner stabilizes femur, applies dorsal pressure at proximal tibia while extending stifle
• Positive test: Cranial tibial displacement during extension (concurrent with straightening)
• Sensitivity: 72-98% in CCL-deficient stifles (more sensitive than drawer test in early disease)
• Interpretation: May be positive with partial tears when drawer test is negative

Diagnostic Approach: Positive drawer test + positive tibial thrust = highly suggestive CCL rupture; confirm with radiography/MRI

Hip Dysplasia Assessment

Ortolani Test

• Position: Dog supine; hip and knee flexed to 90°; examiner abducts femur gently
• Positive test: Audible/palpable "click" or "clunk" as femoral head subluxates into acetabulum (indicates underlying dysplasia)
• Sensitivity/Specificity: 64-82% sensitivity; useful in puppies <6 months; becomes unreliable as fibrosis develops
• Interpretation: Positive Ortolani suggests hip dysplasia; negative result does not rule out disease

Distraction Index (radiographic measurement)

• Radiographic assessment required for definitive diagnosis
• PennHIP method: Measures femoral head displacement; DI = 0.3-0.5 (normal), >0.7 (dysplastic)
• Laxity threshold: DI >0.3 suggests increased risk of osteoarthritis

OFA (Orthopedic Foundation for Animals) Scoring

• Classification: Normal, borderline, dysplastic (based on radiographic features: remodeling, bone proliferation, subluxation)
• Age: Radiographs at ≥24 months for certification
• Breed-specific prevalence: German Shepherd (19%), Labrador retriever (12%), Golden retriever (20%)

Patellar Luxation Grading (Putnam Scale)

Diagnosis: Palpation during extension/flexion; ±radiography (assess for trochlear dysplasia, medial angulation); ultrasound if soft tissue damage suspected

Breed Predisposition: Small breeds (Chihuahua, Pomeranian, Toy Poodle); large breed medial luxation less common

Common Conditions by Species and Location

Dogs - Forelimb

1. Shoulder Osteoarthritis (OA): Older dogs; German Shepherd, Labrador predisposed; limited extension; pain on manipulation
2. Elbow Dysplasia: Large/giant breeds; medial coronoid process disease (MCPD), osteochondrosis dissecans (OCD), ununited anconeal process (UAP); radiography required
3. Carpal/Metacarpal Injuries: Partial tears, ligament sprains; may be career-ending in performance dogs

Dogs - Hindlimb

1. Hip Dysplasia: Large/giant breeds (German Shepherd, Labrador, Golden Retriever); OA secondary; manifests as hindlimb lameness, reluctance to jump, bunny-hopping gait
2. Cranial Cruciate Ligament (CCL) Rupture: Common; large breed predisposition; acute grade 3-4 lameness or insidious chronic grade 1-2
3. Patellar Luxation: Small breeds primarily; intermittent lameness or persistent non-weight-bearing
4. Meniscal Tear: Often concurrent with CCL rupture; secondary to OA progression; medial meniscus most common

Cats

1. Hip Dysplasia: Less common than in dogs; Maine Coons, Persians predisposed; may go undiagnosed (cats compensate well)
2. Patellar Luxation: Less common; similar presentation to dogs
3. Osteoarthritis: Underdiagnosed; manifests as reduced jumping, reluctance to climb, behavioral changes; not traditional lameness
4. Fractures: Falls, trauma; radiography essential

Horses

1. Lameness Assessment: AAEP scale (0 = sound, 5 = non-weight-bearing); joint flexion tests; response to intra-articular anesthesia diagnostic
2. Suspensory Ligament Injury: Common in sport horses; ultrasound assessment essential
3. Navicular Disease: Chronic forelimb lameness; radiographic changes (demineralization, ossification); associated with deep digital flexor tendon pathology

OFA Hip Dysplasia Score Interpretation

Limitations

• Drawer test: Insensitive in early CCL disease or with protective muscle guarding; serial examinations more reliable than single assessment
• Ortolani test: Unreliable >6 months of age as fibrosis prevents subluxation; PennHIP method more sensitive in adult dogs
• Palpation: Limited sensitivity for meniscal tears; MRI required for definitive diagnosis
• Radiographic interpretation: Subtle early changes may be missed; positioning essential for accurate assessment
• Breed predispositions: Wide individual variation; screening recommendations vary by breed and organization
• Referral to board-certified surgeon recommended for: CCL rupture with surgical consideration, multiple joint involvement, fracture management, advanced OA, undiagnosed lameness after clinical/radiographic workup