Chapter 101 - Stifle Flashcards
What is the approximate volume of the medial femorotibial compartment (MFT) in mL?
a) 31.67 mL ± 5.77 mL
b) 41.67 mL ± 5.77 mL
c) 51.67 mL ± 2.89 mL
d) 61.67 mL ± 2.89 mL
Answer: b) 41.67 mL ± 5.77 mL
What percentage of horses show communication between the femoropatellar joint (FP) and the medial femorotibial joint (MFT)?
a) 60% to 65%
b) 70% to 75%
c) 80% to 85%
d) 90% to 95%
Answer: a) 60% to 65%
In which percentage of limbs does mepivacaine diffusion occur from the LFT to the FP?
a) 80%
b) 85%
c) 90%
d) 95%
Answer: c) 90%
The standing femorotibial joint angle is approximately:
a) 140 degrees
b) 150 degrees
c) 160 degrees
d) 170 degrees
Answer: b) 150 degrees
What is the percentage range of horses showing communication between the femoropatellar joint (FP) and the lateral femorotibial joint (LFT)?
a) 1% to 5%
b) 5% to 10%
c) 10% to 25%
d) 25% to 50%
Answer: c) 1% to 25%
At what age is the patella fully ossified in horses?
a) 2 months
b) 4 months
c) 6 months
d) 12 months
Answer: b) 4 months
How many centers of ossification does the stifle of a horse have at birth?
a) 4
b) 5
c) 6
d) 7
Answer: c) 6
What is the approximate sensitivity of ultrasonography for identifying meniscal injuries compared to arthroscopic findings?
a) 65%
b) 70%
c) 79%
d) 85%
Answer: c) 79%
The apophyseal-epiphyseal physis of the tibial tuberosity closes at what age?
a) 6 to 9 months
b) 9 to 12 months
c) 12 to 15 months
d) 15 to 18 months
Answer: b) 9 to 12 months
The lateral femorotibial compartment (LFT) has a volume of approximately how many mL?
a) 51.67 mL ± 2.89 mL
b) 61.67 mL ± 2.89 mL
c) 71.67 mL ± 5.77 mL
d) 81.67 mL ± 5.77 mL
Answer: b) 61.67 mL ± 2.89 mL
How long is the distal femoral physis open in horses?
a) 12 to 18 months
b) 18 to 24 months
c) 24 to 30 months
d) 30 to 36 months
Answer: c) 24 to 30 months
What is the maximum degree of external rotation the tibia undergoes during the screw home mechanism?
a) 5 degrees
b) 6 degrees
c) 8 degrees
d) 10 degrees
Answer: c) 8 degrees
What is the false positive rate of ultrasonography for identifying meniscal injuries compared to arthroscopic findings?
a) 30%
b) 40%
c) 56%
d) 70%
Answer: c) 56%
At what angle should the x-ray beam be directed for the caudocranial view of the stifle?
a) 0 to 10 degrees
b) 10 to 20 degrees
c) 20 to 30 degrees
d) 30 to 40 degrees
Answer: b) 10 to 20 degrees
What is the volume of the medial femorotibial compartment (MFT) of the stifle joint?
A) 41.67 mL ±5.77 mL
B) 61.67 mL ±2.89 mL
C) 50.00 mL ±4.00 mL
D) 30.00 mL ±3.00 mL
Answer: A) 41.67 mL ±5.77 mL
The standing femorotibial joint angle is approximately:
A) 140 degrees
B) 150 degrees
C) 160 degrees
D) 180 degrees
Answer: B) 150 degrees
What percentage of horses typically show communication between the femoropatellar joint (FP) and the medial femorotibial joint (MFT)?
A) 30% to 40%
B) 50% to 55%
C) 60% to 65%
D) 70% to 75%
Answer: C) 60% to 65%
How much mepivacaine diffusion occurs from the lateral femorotibial joint (LFT) to the femoropatellar joint (FP)?
A) 80%
B) 85%
C) 90%
D) 100%
Answer: C) 90%
What ligament is NOT part of the stifle joint’s supporting soft tissue structures?
A) Cranial cruciate ligament
B) Medial femoropatellar ligament
C) Radial collateral ligament
D) Lateral collateral ligament
Answer: C) Radial collateral ligament
The presence of upward fixation of the patella is indicated by:
A) Inability to extend the stifle
B) Inability to flex the stifle
C) Reduced weight bearing
D) Increased gait abnormalities
Answer: B) Inability to flex the stifle
Which imaging technique is particularly beneficial for evaluating obscured regions of the stifle?
A) Radiography
B) Ultrasonography
C) Computed tomography (CT)
D) Nuclear scintigraphy
Answer: B) Ultrasonography
The sensitivity and specificity of ultrasonography for identifying meniscal injuries when compared to arthroscopic findings is:
A) 50% sensitivity, 70% specificity
B) 79% sensitivity, 56% specificity
C) 85% sensitivity, 90% specificity
D) 100% sensitivity, 100% specificity
Answer: B) 79% sensitivity, 56% specificity
The primary purpose of intraarticular anesthesia in stifle diagnostics is to:
A) Provide pain relief
B) Localize lameness
C) Enhance imaging quality
D) Decrease joint swelling
Answer: B) Localize lameness
How many centers of ossification does the stifle of the horse have at birth?
A) Four
B) Five
C) Six
D) Seven
Answer: C) Six
What is the main diagnostic advantage of using CT arthrography over other techniques?
A) It is the least invasive
B) It offers superior identification of soft tissue injuries
C) It provides detailed visualization of bone and cartilage injuries
D) It is the fastest imaging technique
Answer: C) It provides detailed visualization of bone and cartilage injuries
What anatomical feature allows for the “screw home mechanism” in the equine stifle?
A) The shape of the patella
B) The interaction of cruciate and collateral ligaments
C) The thickness of the menisci
D) The size of the femoral condyles
Answer: B) The interaction of cruciate and collateral ligaments
The cranial pouch of the lateral femorotibial compartment contains which anatomical structure?
A) Patellar ligament
B) Peroneus tertius tendon
C) Cranial cruciate ligament
D) Medial meniscus
Answer: B) Peroneus tertius tendon
The volume of the lateral femorotibial compartment (LFT) is approximately:
A) 30.00 mL ±1.00 mL
B) 41.67 mL ±5.77 mL
C) 50.00 mL ±2.00 mL
D) 61.67 mL ±2.89 mL
Answer: D) 61.67 mL ±2.89 mL
Which imaging technique is considered unreliable for detecting soft tissue injuries in the stifle?
A) CT
B) MRI
C) Nuclear scintigraphy
D) Ultrasonography
Answer: C) Nuclear scintigraphy
What anatomical structure is the primary site for identifying cartilage lesions in the stifle using radiography?
A) Medial femoral condyle
B) Lateral trochlear ridge
C) Patella
D) Tibial tuberosity
Answer: A) Medial femoral condyle
The cranial meniscotibial ligament is best visualized in which imaging modality?
A) MRI
B) Radiography
C) Ultrasonography
D) Nuclear scintigraphy
Answer: A) MRI
The cranial cruciate ligament can be assessed through which of the following tests?
A) Tarsal flexion test
B) Stifle flexion test
C) Patellar reflex test
D) Cranial drawer test
Answer: D) Cranial drawer test
What happens to the tibia during the “screw home mechanism”?
A) It undergoes internal rotation
B) It undergoes external rotation
C) It locks into extension
D) It flexes more than normal
Answer: B) It undergoes external rotation
What is the best view to obtain for demonstrating medial femoral condyle cysts?
A) Caudocranial view
B) Lateral view
C) Skyline view
D) Oblique view
Answer: A) Caudocranial view
At what age is the patella fully ossified in horses?
A) 2 months
B) 4 months
C) 6 months
D) 12 months
Answer: B) 4 months
Which of the following is a common indicator of stifle lameness?
A) Increased flexion of the hock
B) Shortened anterior phase of stride
C) High stepping gait
D) Increased toe wear on the contralateral limb
Answer: B) Shortened anterior phase of stride
What anatomical structure primarily contributes to the passive stay apparatus of the hindlimb?
A) Medial meniscus
B) Patellar ligament
C) Trochlear ridges
D) Femorotibial joint
Answer: B) Patellar ligament
What is the primary disadvantage of using ultrasonography in stifle diagnostics?
A) High cost
B) Limited resolution of deep structures
C) Difficulty in visualizing soft tissues
D) Operator-dependent accuracy
Answer: B) Limited resolution of deep structures
The medial and lateral femoropatellar ligaments are important for:
A) Stabilizing the femoropatellar joint
B) Enhancing joint mobility
C) Allowing for patellar movement
D) All of the above
Answer: A) Stabilizing the femoropatellar joint
What is the role of the menisci in the stifle joint?
A) Provide cushioning between femur and tibia
B) Facilitate blood flow to the joint
C) Assist in synovial fluid production
D) Stabilize the patella
Answer: A) Provide cushioning between femur and tibia
Which anatomical structure connects the lateral femoral condyle to the tibia?
A) Medial collateral ligament
B) Lateral collateral ligament
C) Cranial cruciate ligament
D) Patellar tendon
Answer: B) Lateral collateral ligament
What is the primary indicator of stifle joint effusion on physical examination?
A) Increased temperature of the joint
B) Decreased range of motion
C) Swelling around the joint
D) Increased sensitivity to palpation
Answer: C) Swelling around the joint
What is the significance of the patellar locking mechanism?
A) It allows for weight-bearing without muscle contraction
B) It improves blood circulation to the joint
C) It enhances flexibility of the stifle joint
D) It prevents patellar dislocation
Answer: A) It allows for weight-bearing without muscle contraction
The presence of a “flipped” lateral meniscus indicates which type of injury?
A) Meniscal tear
B) Ligament rupture
C) Cartilage damage
D) Synovitis
Answer: A) Meniscal tear
Which joint compartment is the most commonly affected by osteochondritis dissecans in horses?
A) Femoropatellar joint
B) Lateral femorotibial joint
C) Medial femorotibial joint
D) All compartments equally
Answer: A) Femoropatellar joint
What technique is commonly used to obtain synovial fluid from the stifle joint for analysis?
A) Arthroscopy
B) Ultrasound-guided injection
C) Needle aspiration
D) Open surgical biopsy
Answer: C) Needle aspiration
Figure 101-1. Anatomy of the equine stifle, cranial view, showing: a, parapatellar fibrocartilage; b, medial patellar ligament; c, medial collateral ligament; d, tibial tuberosity; e, cut stump of the biceps femoris muscle; f, middle patellar ligament; g, lateral patellar ligament; h, lateral collateral ligament; i and k, medial and lateral condyles of the tibia.
Figure 101-3. Fluoroscopic image of the LFT of an equine cadaver stifle after injection of positive contrast medium into the caudal pouch of the LFT showing distention of the proximal pocket of the caudal pouch (CP) of the LFT, the distal extension of the LFT called the subextensor recess located in the sulcus muscularis (SM), and the distal pocket of the caudal pouch of the LFT (arrows).
Figure 101-5. Cruciate ligament test used to detect rupture. The shoulder is placed against the back of the limb and the tibia is pulled caudad and released.
Figure 101-2. Anatomy of the equine stifle, lateral view, showing: a, femoropatellar joint (FP); b, middle patellar ligament; c, medial patellar ligament; d, cut stump of the lateral patellar ligament; e, long digital extensor muscle; f, lateral femoropatellar ligament; g, popliteus muscle; h, lateral tibial condyle; i, lateral digital extensor muscle.
Figure 101-4. Appearance of bilateral FP effusion
Figure 101-7. A caudal 30-degree lateral craniomedial oblique radiographic view of the stifle highlights an osteochondrosis lesion (arrow) of the lateral trochlear ridge of the femur.
Figure 101-6. An avulsion fracture (arrow) is evident on this lateromedial stifle radiograph. The avulsed osseous fragment is evident near the distal insertion of the cranial cruciate ligament on the central intercondylar area located just lateral to the medial intercondylar eminence of the tibia (MICET). Avulsion fractures in this area can be from the cranial meniscotibial ligaments or the cranial cruciate ligament insertion sites and cannot be definitively differentiated on x-rays.
Figure 101-8. A caudocranial view of the stifle demonstrating a large subchondral bone cyst (arrows) in the medial femoral condyle.
Figure 101-9. Cranioproximal craniodistal oblique radiographic view (skyline) of the equine stifle, which is used to evaluate the patella, intertrochanteric groove of the femur, and trochlear ridges. Note the sagittal fracture of the medial aspect of the patella (arrow).
Figure 101-10. A transverse CT image section of an equine cadaveric distal femur and patella at the level of the proximal aspect of the medial and lateral femoral condyles. Injection of the caudal pouches of the femorotibial joints with shaving cream prior to imaging shows the extent of distention of these pouches. The popliteal artery and vein (arrow) run in the septum separating the caudal pouches. L, Lateral femoral condyle; M, medial femoral condyle. (
Figure 101-11. A T1-weighted VIBE magnetic resonance image of the stifle in the dorsal plane revealed a large area of bone edema, high signal (with contrast enhancement) in the subchondral bone, and extensive cartilage injury in the lateral femoral condyle (arrow) that was not evident on routine radiographs.
