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The Knee Complex. A.General Structure & Function B.Structure & Function of Specific Joints C.Muscular Considerations.

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Presentation on theme: "The Knee Complex. A.General Structure & Function B.Structure & Function of Specific Joints C.Muscular Considerations."— Presentation transcript:

1 The Knee Complex

2 A.General Structure & Function B.Structure & Function of Specific Joints C.Muscular Considerations

3 General Structure

4

5 Joints of the Knee Complex

6 General Function Provides very mobile link in an otherwise stable lower extremity Transmits loads from tibia/fibula to femur

7

8

9 Knee Complex Movements

10 Sagittal plane Flexion, extension Transverse plane Medial and lateral rotation

11 Knee Complex Movements Frontal plane Varus, valgus Anteroposterior translation Mediolateral translation

12 The Knee Complex A.General Structure & Function B.Structure & Function of Specific Joints C.Muscular Considerations

13 Structure & Function of Specific Joints 1.Tibiofibular Joint 2.Patellofemoral Joint 3.Tibiofemoral Joint

14 Tibiofibular Joint: Bony Structure Amphiarthrodial membranous syndesmosis joint

15 Structure & Function of Specific Joints 1.Tibiofibular Joint 2.Patellofemoral Joint 3.Tibiofemoral Joint

16 Purpose of Patella Increase leverage of QF Protect joint during knee flexion ↓ pressure and distribute forces on femur Prevent F compression on PT in resisted knee flexion Disadvantage:  ANT shear of QF

17 Patella Structure Medial facet Lateral facet Odd facet (30%) M L

18 PF Articular Surfaces Largest sesamoid bone Least congruent joint Articular cartilage Vertical ridge Facets M L

19 PF Articular Surfaces Largest sesamoid bone Least congruent joint Articular cartilage Vertical ridge Facets Angle of femoral sulcus

20 Patellar Motion INF & SUP Sliding Patellar tilt 11  MT as KN FL Med Lat

21 Patellar Motion Lateral rotation ACC MR of femur 6  through KN FL Medial rotation ACC LR of femur

22 Patellalectomy ↓ MA of QF (↓ strength 49%)  Q tendon friction  compressive stress on groove by Q tendon Most evident in closed chain EXT ECC QF in CC Coupled w/ & assisted by hip & ankle movement QF not needed in erect posture of CC

23 Little effect overall Extension

24 Noticeable weakness Slight Flexion

25 Noticeable weakness Extreme Flexion

26 From 0° to 60° of Knee Flexion

27 0  -60  Contact area   MA of QF;  60   ANT shear of QF 0  -60  Facet contact at 20 

28 From 60° to 140° of Knee Flexion

29 60  -140   contact area  MA of QF No leverage in full FL

30 Overall Medial facet most contact Odd facet least contact

31 During Full Extension Full EXT  MA of QF  QF length Patella very unstable

32 PF JRF Amount of knee FL Strength of QF contraction

33

34 PF Compressive Forces Descending stairs4000 N Max isometric extension6100 N Kicking6800 N Parallel squat14,900 N (7-8X BW) Isokinetic knee extension8300 N Rising from chair3800 N Running/jogging5000 N (3-4X BW) Ascending stairs1400 N Walking N ( X BW) Cycling880 N

35 Compensatory Mechanisms for Compressive Force Distribution Contact area  with knee flexion Medial facet contact from 30  -70  Thickest hyaline cartilage in body

36

37 Compensatory Mechanisms for Compressive Force Distribution Contact area  with knee flexion Medial facet contact from 30  -70  Thickest hyaline cartilage in body Largest QF MA 30  -70   QF torque as MA decreases QF tendon contacts condyles 70  -90 

38 Normal Patella Tracking Maintains maximum congruence Passive restraints Active restraints

39 Abnormal Patella Tracking ↓ congruence Stretches capsule & retinacula ↓ contact area LateralMedial

40 Causes of Abnormal Tracking Skeletal abnormalities Strength imbalance in QF Strength imbalance in fibrous tissues Compensatory movements in knee due to abnormal foot movement

41 Causes of Abnormal Tracking Skeletal abnormalities Strength imbalance in QF Strength imbalance in fibrous tissues Compensatory movements in knee due to abnormal foot movement

42 Skeletal Abnormalities: Q-angle

43 Skeletal Abnormalities: Genu Varum & Genu Valgum Q angle  w/ age Varum common in very young children Valgum seen in growing children Menisectomy effects

44 Skeletal Abnormalities: Patella Alta & Patella Baja Index of Insall & Salviti LT/LP Normal = 1.0 Patella alta = 0.8 Patella baja = 1.2 Women  ratio

45 Skeletal Abnormalities: Patella Surface Lateral Border Appositional forces ↓ in full extension Prominence of lateral border prevents lateral displacement Underdevelopment common in children as growing

46 Skeletal Abnormalities: Femoral & Tibial Torsion Lateral tracking

47 Causes of Abnormal Tracking Skeletal abnormalities Strength imbalance in QF Strength imbalance in fibrous tissues Compensatory movements in knee due to abnormal foot movement

48 QF Strength Imbalance

49 Causes of Abnormal Tracking Skeletal abnormalities Strength imbalance in QF Strength imbalance in fibrous tissues Compensatory movements in knee due to abnormal foot movement

50 Fibrous Tissue Strength Imbalance IT

51 Causes of Abnormal Tracking Skeletal abnormalities Strength imbalance in QF Strength imbalance in fibrous tissues Compensatory movements in knee due to abnormal foot movement

52 Compensatory Movement Pronation of foot accompanied by medial rotation of tibia  medial rotation & medial translation of patella Pronation coupled w/ forceful quadriceps femoris leads to anterior tilt EX: jumping, landing, running

53 Summary


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