Ch 61 - Anatomy and Kinematics of the Stifle Joint Flashcards
List the sesamoids of the stifle joint
- Patella
- Lateral fabella (larger and more spherical)
- Medial fabella
- Popliteal sesamoid bone (smallest, within tendon of origin of popliteus muscle, articulates with lateral condyle of tibia
List the three articulation of the stifle
- Femorotibial
- Femoropatellar
- Proximal tibiofibular
What are the cruciate ligaments made of?
- Core region of fascicles containing collagen fibrils and fibroblasts
- Covered by an epiligamentous region composed of synovial intima and underlying loose connective tissue (absent where cranial wraps around caudal)
- Abundant mechanorecpetors and proprioceptors in center
What is the composition of the menisci?
- Fibrocartilage, primarily made up of Type I collagen fibers
- Extracellular matrix of proteoglycans and glycoproteins
- Surface layers are randomly orientated for low-friction movement
- Innermost third - radial pattern of collagen
- Outermost 2/3 - circumferential pattern of collagen
- Dispersed radial ‘tie-fibers’ throughout bulk to resist longitudinal splitting
List the differences in the attachments of the medial and lateral menisci
- Medial is firmly attached to medial collateral via the coronary ligament, lateral is not
- Medial is firmly attached to tibia via cranial and caudal meniscotibial ligments. Lateral may or may not have small caudal meniscotibial attachments however it does have a meniscofemoral ligament to the intercondyloid fossa
- Popliteal-meniscal fascicles attach the lateral meniscus to the popliteal tendon
What supplies blood to the meniscus?
What are the three vascula zones?
- Medial and lateral genicular arteries as well as a reflection of the synovium
- The peripheral 15-25% of the meniscus is vascular
Zones:
- Red-red zone: Peripheral zone, rich blood supply
- Red-white zone: Intermediate zone, small number of vessesl
- White-white zone: Axial layer, avascular
What is the normal range of motion of the stifle?
- standing angle: 140 degrees
- flexion 41 deg
- extension 161 deg
Which collateral are taut in flexion and extension?
- Extension: Both are taut (primary stabilisers against rotation)
- Flexion: Lateral is loose, medial is taut except for the caudal border
What occurs in response to increased strain in the cranial cruciate ligament?
Contraction of the caudal thigh muscles and relaxation of the quadriceps femoris
What are the main functions of the menisci?
- Load bearing
- Load distribution
- Shock absorption
- Joint stability
How much of the weight across the stifle do the menisci bear?
40 - 70%
What is hoop stress?
Compressive forces on the menisci cause the wedge shaped menisci to extrude peripherally, resulting in elongation of the circumferentially orientated collagen fibres
How do various meniscectomies change the joint biomechanics?
- Smaller (30% radial width) partial meniscectomies has minimal effects on biomechanics and function
- Larger (75% radial width) partial meniscectomies and hemimeniscectomies resuted in significant changes in medial and femorotibial contact mechanics
To act as a functional unit, the meniscus needs more than 25% of the radial width of the peripheral tissue
What are the two options of meniscal release?
- Mid-body
- Transection of caudal meniscotibial ligament of medial meniscus
No significant differences between the two! Meniscal release is similar to hemimeniscectomy in regards to meniscal function but less radical meniscal excision is associated with less disruption of chondrocytes
How does CCLR change the peak vertical force?
Normal dogs have PVF of 70% of static BW on limb
After CCLR:
- 25% at 2 weeks
- 32% at 6 weeks
- 37% at 12 weeks
Name the following types of meniscal tears
- A: Intact
- B: Vertical longitudinal tear
- C: Bucket Handle tear
- D: Flep tear
- E: Radial tears
- F: Horizontal tear
- G: Complex tear
- H: Degenerative tear
