Chapter 101 - Stifle

Question 1

1. What are the 2 articulations of the stifle?

Answer 1

• Femoropatellar joint
• Femorotibial joint

Question 2

2. The joint capsule of the FPJ inserts abaxially where?

Answer 2

• On the trochlear ridges

Question 3

3. T/F – communication between the MFT and LFT is not present under normal conditions.

Answer 3

• True

Question 4

4. The cranial and caudal pouches of the femorotibial joints are divided by the _________?

Answer 4

• Femoral condyles

Question 5

5. What is the volume of the MFT vs LFT?

Answer 5

• Medial ~42mL +/- 5.7mL
• Lateral ~61.7mL +/-3mL

Question 6

6. Describe the distal extension of the LFT cranial pouch joint capsule.

Answer 6

• Called the subextensor recess, it surrounds the peroneus tertius and long digital extensor tendon. It is located in the sulcus muscularis

Question 7

7. Describe the weight bearing region of the FTJ.

Answer 7

• The medial and lateral condyles of the distal femur articulate with the respective tibial condyles

Question 8

8. What is the joint angle of the FTJ when standing vs. under hyperextension?

Answer 8

• Standing 150°
• Hyperextension 155°-160°

Question 9

9. Describe the screw home mechanism.

Answer 9

• The tibia undergoes ~8 degrees of external rotation from 110 to 150 ° stifle angles

Question 10

10. Communication between the FPJ and LFT occurs in what percentage of horses?

Answer 10

• Between 1-25%

Question 11

11. Communication between the FPJ and MFT occurs in what percentage of horses?

Answer 11

• Between 60%-65%

Question 12

12. List the 5 (as per Auer/ all 7) ligaments associated with the medial and lateral meniscus.

Answer 12

• Lateral Cranial meniscotibial ligament
• Lateral caudal meniscotibial ligament
• Medial cranial meniscotibial ligament
• Medial caudal meniscotibial ligament
• Meniscofemoral ligament

Question 13

13. List the soft tissue support structures of the stifle as per Auer.

Answer 13

• Medial patellar ligament
• Middle patellar ligament
• Lateral patellar ligament
• Medial femoropatellar ligament
• Lateral femoropatellar ligament
• Medial collateral ligament
• Lateral collateral ligament
• Cranial cruciate ligament
• Caudal cruciate ligament
• 5 meniscal ligaments (4 meniscotibial and 1 meniscofemoral)

Question 14

14. Where do the collateral ligaments of the stifle originate and insert?

Answer 14

• Originate on the femoral epicondyles
• Insert on a roughened area just distal to the margin of the tibial condyle (medial) and the head of the fibula (lateral)

Question 15

15. The popliteal tendon runs underneath the _____ with a bursa interposed between the two

Answer 15

• Lateral collateral ligament

Question 16

17. The ___________ runs from the lateral wall of the intercondyloid fossa of the femur and inserts lateral to the medial intercondylar eminence of the tibia

Answer 16

• Cranial cruciate ligament

Question 16

16. Describe the location of the cranial cruciate ligament

Answer 16

• Arises from the lateral wall of the intercondyloid fossa of the femur
• Runs craniad and distad
• Inserts just lateral to the medial intercondylar eminence of the tibia

Question 17

18. Describe the path of the caudal cruciate ligament

Answer 17

• Arises from the cranial aspect of the medial wall of the intercondyloid fossa and inserts on the caudal part of the central intercondylar area and on an eminence at the popliteal notch of the tibia

Question 18

19. The cruciate ligaments are intra- or extra- synovial?

Answer 18

• Extrasynovial

Question 19

20. ## What cruciate ligament is under tension when the stifle is in extension?

Answer 19

Cranial cruciate ligament

Question 20

21. ___________ are paired semilunar fibrocartilaginous discs interposed between the convex femoral and relatively flat tibial condyles

Answer 20

• Menisci

Question 21

22. How many meniscal ligaments are there?

Answer 21

• 5

Question 22

23. What are the 5 ligaments of the menisci?

Answer 22

• 4 meniscotibial ligaments at the axial aspects of the cranial and caudal horns
• 1 meniscofemoral ligament attaches the caudal horn of the lateral meniscus to the femur

Question 23

24. What is a Grade I Meniscal stifle tear?

Answer 23

• Tears extending longitudinally down the cranial meniscotibial ligament into the cranial horn of the meniscus with minimal separation of the tissues

Question 24

25. What is a Grade II Meniscal stifle tear?

Answer 24

- Tears of similar orientation to grade I tears, but with further separation of tissue, where the extent of the injury remains fully visible on arthroscopic exam

Question 25

26. What is a Grade III Meniscal stifle tear?

Answer 25

- Severe tears that extend beneath the femoral condyle and cannot be fully visualized arthroscopically

Question 26

27. What is the largest sesamoid bone in the body?

Answer 26

- The patella

Question 27

28. What is the origin of the peroneus tertius?

Answer 27

- The extensor fossa of the femur just lateral to the distal aspect of the lateral trochlear ridge

Question 28

29. The peroneus tertius shares its origin with what tendon?

Answer 28

- The long digital extensor tendon