Ch 61 - Anatomy and Kinematics of the Stifle Joint Flashcards

1
Q

List the sesamoids of the stifle joint

A
  • 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
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2
Q

List the three articulation of the stifle

A
  • Femorotibial
  • Femoropatellar
  • Proximal tibiofibular
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3
Q

What are the cruciate ligaments made of?

A
  • 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
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4
Q

What is the composition of the menisci?

A
  • 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
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5
Q

List the differences in the attachments of the medial and lateral menisci

A
  • 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
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6
Q

What supplies blood to the meniscus?
What are the three vascula zones?

A
  • 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

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7
Q

What is the normal range of motion of the stifle?

A
  • standing angle: 140 degrees
  • flexion 41 deg
  • extension 161 deg
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8
Q

Which collateral are taut in flexion and extension?

A
  • Extension: Both are taut (primary stabilisers against rotation)
  • Flexion: Lateral is loose, medial is taut except for the caudal border
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9
Q

What occurs in response to increased strain in the cranial cruciate ligament?

A

Contraction of the caudal thigh muscles and relaxation of the quadriceps femoris

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10
Q

What are the main functions of the menisci?

A
  • Load bearing
  • Load distribution
  • Shock absorption
  • Joint stability
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11
Q

How much of the weight across the stifle do the menisci bear?

A

40 - 70%

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12
Q

What is hoop stress?

A

Compressive forces on the menisci cause the wedge shaped menisci to extrude peripherally, resulting in elongation of the circumferentially orientated collagen fibres

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13
Q

How do various meniscectomies change the joint biomechanics?

A
  • 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

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14
Q

What are the two options of meniscal release?

A
  • 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

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15
Q

How does CCLR change the peak vertical force?

A

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

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16
Q

What procedure can be performed in a skeletally immature dog with CCLR?
What is a potential complication?

A

Epiphysiodesis
Can cause valgus deformity as a result of eccentric insertion or angulation of the screw

17
Q

List some potential causes of CCLR

A
  • Obesity of poor fitness may mitigate the protective effects of the reflex responses to CCL mechanoreceptors
  • Progressive mechanical overload (decreased birefringence and elongation of crimping in remaining collagen fibrils)
  • Immune-mediated
  • Acquired loss of blood supply
  • Smaller intercondylar notch width
18
Q

What percentage of dogs will go on the rupture the CCLR on the contraleteral limb?

A

22 - 54%

19
Q

What is the sensitivity and specificity of ultrasound for diagnosing meniscal pathology?

A
  • Sensitivtiy 90%
  • Specificity 92.9%
20
Q

What is the reported incidence of meniscal injury in dogs diagnosed with CCLR?

A

30 - 80%

21
Q

What is the incidence of lateral meniscal tears in dogs with CCLR?

A

77% radial tears of the axial edge of the lateral meniscus. Significance unknown

22
Q

What is the difference between a postliminary meniscal and a latent meniscal tear?

What is the incidence of late meniscal tears (of both kinds combined)

A
  • Postliminary - Tears that occur after the initial surgery
  • Latent - Tears which are present at the time of the initial surgery but are not identified
  • Incidence 2.8 - 27.8 %
23
Q

What are some risk factors for developing meniscal tears?

A
  • Overweight dogs
  • Chronic and complete CCLR
  • TTA 3x more likely vs TPLO
  • TTA 6x more likely vs Tightrope
24
Q

What percentage of dogs with meniscal tears will have a palpable or audible meniscal click?
What is the sensitivity and specificty of this test?

A

27%
- Sensitivty 50%
- Specificity 90%

25
Q

Dogs with complete CCLR are how much more likely to have a meniscal tear compared to partial CCLR?

A

9.6 times more likely with a complete tear

26
Q

What percentage of cats with CCLR will have radiography meniscal mineralisation?

A

46%

27
Q

Name the following types of meniscal tears

A
  • 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
28
Q

How do you achieve the best view of the medial meniscus?

A
  • Stifle at 110-130 degrees
  • External rotation and valgus stress
29
Q

List the types of meniscectomy

A
  • Caudal meniscectomy (segmental)
  • Total meniscectomy
  • Partial meniscectomy (removal of damaged axial section while preserving cranial and caudal meniscotibial ligaments and peripheral rim)
30
Q

At what angle does the meniscus need to be cut to achieve a complete release?

A

30 degrees

31
Q

What is the reported improvement after meniscectomy for postliminary meniscal tear?

A

88%