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Biomechanics of
Knee Complex
BPT Year 1 Semester 2
Lecture 1
Contents
1. Introduction
2. Function
3. Tibio-femoral joint and Patellofemoral joint
4. Articular surfaces
5. Capsule, lig...
Introduction
 Largest and one of the most complex joints
 Major stability and mobility roles
3
Functions:
 Functional shortening and lengthening of the
extremity by flexion and extension
 Supports body during dynami...
Knee complex
Tibio- femoral Patello-femoral
5
Tibio-femoral Joint
 Type of Joint?
 Double Condyloid joint
 Degrees of freedom of
motion?
 Flexion/ Extension
 Media...
Articular surfaces
Articular surfaces
Proximal Articular Surface:
 femoral condyles
 Medial condyle larger than lateral
Distal Articular Su...
Alignment of knee
• The Anatomical axis of
femur is oblique directed
inferiorly and medially.
• Anatomical axis of tibia i...
Alignment of knee
 Normally knee forms lateral
angle of 170o-175o
Variation:
 Genu valgum or Knock knee-
lateral angle <...
Alignment of knee
11
Menisci
Fibrocartilagenous disc
Functions
Blood supply
Mechanism of injury
Menisci: Functions
 Improves congruence of joint
 Distributes weight bearing forces
 Decreases friction between tibia a...
Nutrition
 First year of life: contains blood vessels
throughout meniscal body
 Vascularity decreases with age
 Outer 2...
Prolonged immobilization or
non-weight bearing?
 Menisci does not receive appropriate nutrition
 Avascular nature of cen...
Compression forces at the knee:
 While walking- 2.5 – 3 times body weight
 Ascending stairs: 4 times
 Menisci triples t...
Mechanisms of meniscal injury
 Forceful, rotation of femoral condyle on partially
flexed and weight bearing knee
 locked...
Test for Miniscal injury
 Apley’s Grinding Test
 McMurray’s Test
18
19
• Capsule
• Collateral Ligament
• Cruciate ligament
20
Capsule and Ligaments
Capsule
 Encloses medial and lateral tibio-femoral joint
and patello-femoral joint.
 Two layers of capsule: Fibrous laye...
Capsule:
Fibrous layer
 Three layers:
1. Extensor retinaculum: anteriorly
2. Fascial layer: distal quadriceps muscle
3. D...
Capsule:
Synovial layer
 Internal surface of the capsule is lined by
synovial membrane.
 Role:
1. secretion of synovial ...
MCL
LCL
Collateral ligaments
Medial collateral ligament (MCL)
• Originates from medial
epicondyle of femur
• Inserted into medial tibial
plateau, media...
MCL: Applied aspect
 Injury when valgus stress is
delivered over a planted foot.
 Common in football players
 MCL is ri...
Lateral collateral ligament (LCL)
27
 Extracapsular
 Origin: Lateral femoral
condyle
 Insertion: fibular head
 Checks ...
Anterior cruciate ligament
Posterior cruciate ligament
Cruciate ligaments
29
Anterior Cruciate Ligament
30
 Inferior attachment: anterior tibial spine
 Extends superiorly, posteriorly to attach to ...
Anterior Cruciate Ligament
31
 Functions:
 Restrains anterior translation of tibia on femur
 Prevents hyperextension of...
Mechanism of injury- ACL
 Most common injury
 Football, downhill skiing, basketball and soccer
players
 Mechanism:
 Co...
Posterior Cruciate Ligament
33
• Origin: Posterior inter-condylar area of tibia
• Insertion: Lateral side of Medial femora...
Functions- PCL
 Primary restraint to posterior translation of
tibia on femur
 Limits the anterior translation of femur o...
Mechanism of injury- PCL
 Three mechanisms
1. Pretibial trauma (Dashboard trauma)
2. Hyper flexion (in thin individual)
3...
Muscles Aiding Tibial Translation
 Anterior Translation:
1. Quadriceps
2. Gastrocnemius
 Posterior Translation:
1. Soleu...
Other ligaments
 Oblique popliteal ligament
 Anterolateral ligament (newer ligament)
List out all other ligaments and it...
Bursae
Bursae
 14 bursae
 Reduce friction between intertissue junction
during movement.
 Activities that involve excess and re...
Bursae
41
 Suprapatellar
 Prepatellar
(Housemaid’s
knee)
 Infrapatellar
(Clergyman’s knee)
Bursitis
42
Prepatellar bursitis
(housemaid’s knee)
 Infrapatellar bursitis
(clergyman’s knee)
Plicae
Plicae
Synovial membrane formation occurs in early
embryonic development
Synovial membrane separates medial and lateral
ar...
Plicae
Failure of complete resorption results in
persistent folds called PLICAE
Plicae may get inflamed or irritated-
Plic...
Summary
 Articular components
 Menisci
 Capsule
MCL, LCL, ACL, PCL
 Ligaments
 Bursae
 Plicae
46
References:
 Neumann DA. Kinesology of musculoskeletal
system, Foundation for Physical Rehabilitation ,
2nd Edition
 Nor...
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1. biomechanics of the knee joint basics

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1. biomechanics of the knee joint basics

  1. 1. Biomechanics of Knee Complex BPT Year 1 Semester 2 Lecture 1
  2. 2. Contents 1. Introduction 2. Function 3. Tibio-femoral joint and Patellofemoral joint 4. Articular surfaces 5. Capsule, ligaments and Menisci 6. Muscles around the knee 2
  3. 3. Introduction  Largest and one of the most complex joints  Major stability and mobility roles 3
  4. 4. Functions:  Functional shortening and lengthening of the extremity by flexion and extension  Supports body during dynamic and static activities  Closed kinematic chain- support body weight in static erect posture  Dynamically- moving and supporting body in sitting and squatting activities, supporting and weight transferring activity during locomotion 4
  5. 5. Knee complex Tibio- femoral Patello-femoral 5
  6. 6. Tibio-femoral Joint  Type of Joint?  Double Condyloid joint  Degrees of freedom of motion?  Flexion/ Extension  Medial/ Lateral rotation  Adduction/ abduction 6
  7. 7. Articular surfaces
  8. 8. Articular surfaces Proximal Articular Surface:  femoral condyles  Medial condyle larger than lateral Distal Articular Surface: Tibial condyles- medial and lateral 8
  9. 9. Alignment of knee • The Anatomical axis of femur is oblique directed inferiorly and medially. • Anatomical axis of tibia is vertical. 9
  10. 10. Alignment of knee  Normally knee forms lateral angle of 170o-175o Variation:  Genu valgum or Knock knee- lateral angle < 170o  Genu vaRum or bow leg- angle > 180o 10 Neumann, 2010
  11. 11. Alignment of knee 11
  12. 12. Menisci Fibrocartilagenous disc Functions Blood supply Mechanism of injury
  13. 13. Menisci: Functions  Improves congruence of joint  Distributes weight bearing forces  Decreases friction between tibia and femur  Shock absorber 13
  14. 14. Nutrition  First year of life: contains blood vessels throughout meniscal body  Vascularity decreases with age  Outer 25% is vasularized by capillaries from joint capsule and synovial membrane  Central blood supply by diffusion from synovial fluid 14
  15. 15. Prolonged immobilization or non-weight bearing?  Menisci does not receive appropriate nutrition  Avascular nature of central portion of meniscus reduces potential of healing after injury  In adults only peripheral portion of meniscus is vasularized hence is capable of inflammation, repair and remodeling after injury or tear. 15
  16. 16. Compression forces at the knee:  While walking- 2.5 – 3 times body weight  Ascending stairs: 4 times  Menisci triples the surface area by significantly reducing the pressure on the articular cartilage  Lateral menisectomy increases pressure at knee by 230% 16 Neumann, 2010
  17. 17. Mechanisms of meniscal injury  Forceful, rotation of femoral condyle on partially flexed and weight bearing knee  locked knee syndrome  Medial meniscus is injured twice as much as lateral  Risk of meniscal injury increases with instability 17
  18. 18. Test for Miniscal injury  Apley’s Grinding Test  McMurray’s Test 18
  19. 19. 19
  20. 20. • Capsule • Collateral Ligament • Cruciate ligament 20 Capsule and Ligaments
  21. 21. Capsule  Encloses medial and lateral tibio-femoral joint and patello-femoral joint.  Two layers of capsule: Fibrous layer Synovial layer 21
  22. 22. Capsule: Fibrous layer  Three layers: 1. Extensor retinaculum: anteriorly 2. Fascial layer: distal quadriceps muscle 3. Deep: medial and lateral retinacula 22
  23. 23. Capsule: Synovial layer  Internal surface of the capsule is lined by synovial membrane.  Role: 1. secretion of synovial fluid 2. Absorption of fluid into joint for lubrication 3. Nutrition to avascular structure like menisci 23
  24. 24. MCL LCL Collateral ligaments
  25. 25. Medial collateral ligament (MCL) • Originates from medial epicondyle of femur • Inserted into medial tibial plateau, medial meniscus, medial proximal tibia. • Restrains excess abduction and lateral rotation stress at knee 25
  26. 26. MCL: Applied aspect  Injury when valgus stress is delivered over a planted foot.  Common in football players  MCL is rich in blood supply hence has good healing 26
  27. 27. Lateral collateral ligament (LCL) 27  Extracapsular  Origin: Lateral femoral condyle  Insertion: fibular head  Checks Varus stress and excessive lateral rotation of tibia
  28. 28. Anterior cruciate ligament Posterior cruciate ligament Cruciate ligaments
  29. 29. 29
  30. 30. Anterior Cruciate Ligament 30  Inferior attachment: anterior tibial spine  Extends superiorly, posteriorly to attach to the postero-medial aspect of the lateral femoral condyle  Two bands:  Anteromedial band (AMB)- taut in flexion  Postero-lateral band (PLB)- taut in extension
  31. 31. Anterior Cruciate Ligament 31  Functions:  Restrains anterior translation of tibia on femur  Prevents hyperextension of knee  Secondary restraint against varus and valgus motion
  32. 32. Mechanism of injury- ACL  Most common injury  Football, downhill skiing, basketball and soccer players  Mechanism:  Common in weight bearing, slight flexion and rotation in either directions  Anterior translatory force on proximal tibia  Hyperextension injury  Hyperflexion in bulky lower extremity muscles 32
  33. 33. Posterior Cruciate Ligament 33 • Origin: Posterior inter-condylar area of tibia • Insertion: Lateral side of Medial femoral condyle • Anteromedial and posterolateral bands
  34. 34. Functions- PCL  Primary restraint to posterior translation of tibia on femur  Limits the anterior translation of femur over fixed tibia in activities such as rapid descending into squat and landing from jump with partially flexed knee 34
  35. 35. Mechanism of injury- PCL  Three mechanisms 1. Pretibial trauma (Dashboard trauma) 2. Hyper flexion (in thin individual) 3. Hyperextension (second ligament to be injured after ACL) 35
  36. 36. Muscles Aiding Tibial Translation  Anterior Translation: 1. Quadriceps 2. Gastrocnemius  Posterior Translation: 1. Soleus 2. Hamstring 36
  37. 37. Other ligaments  Oblique popliteal ligament  Anterolateral ligament (newer ligament) List out all other ligaments and its function referring to articles and reference text books 37
  38. 38. Bursae
  39. 39. Bursae  14 bursae  Reduce friction between intertissue junction during movement.  Activities that involve excess and repetitive force at inter tissue junctions frequently leads to Bursitis. 40
  40. 40. Bursae 41  Suprapatellar  Prepatellar (Housemaid’s knee)  Infrapatellar (Clergyman’s knee)
  41. 41. Bursitis 42 Prepatellar bursitis (housemaid’s knee)  Infrapatellar bursitis (clergyman’s knee)
  42. 42. Plicae
  43. 43. Plicae Synovial membrane formation occurs in early embryonic development Synovial membrane separates medial and lateral articular surface into separate cavities By 12th week of gestation synovial septae reabsorbs to form a single joint cavity 44
  44. 44. Plicae Failure of complete resorption results in persistent folds called PLICAE Plicae may get inflamed or irritated- Plicae Syndrome 45
  45. 45. Summary  Articular components  Menisci  Capsule MCL, LCL, ACL, PCL  Ligaments  Bursae  Plicae 46
  46. 46. References:  Neumann DA. Kinesology of musculoskeletal system, Foundation for Physical Rehabilitation , 2nd Edition  Norkin C, Levengie P. Joint structure and function. 4th Edition  Kapandji IA. The Physiology of Joints. Volume 2, Lower Limb. 5th Edition 47

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