1. The Knee Unit

2. The Knee One of the most complex joints
Provides stability in weight bearing and locomotion
Very vulnerable – especially medially and laterally
Muscles and ligaments provide most of the stability

3. the knee joint is the largest joint space in the body
it is greatest at 30 degrees of flexion
the knee is considered a synovial joint b/c it is aligned with the joint capsule
the synovial layer secretes synovial fluid (like oil to a car) to help lubricate the joint and keep it moving
purpose of synovial fluid
lubrication
nutrient rich

6. BONES
Femur
Patella
Tibia
Fibula

7. Femur largest bone in the body distal end makes up knee
forms convex medial and lateral condyles
medial condyle is larger and longer in the AP direction, which causes external tibial rotation

9. Screw Home Mechanism - external tibial rotation when the knee is fully extended due to the medial condyle being larger than the lateral condyle
proximal end makes up hip
trochlear groove - hollow area between 2 condyles where the patella glides

10. Tibia Weight-bearing bone of lower extremity 2 tuberosities
concave in nature
separated by popliteal notch (Tibial Spine)
ACL & PCL attach to the tibial spine
ACL & PCL are named from their attachment on the tibia
Tibia Fracture

12. Patella Sesmoid bone Function largest one in the body
lies within the quad tendon to increase function
Function
protect anterior knee
increase mechanical advantage

14. patella is most palpable in extension b/c it is above the trochlear groove
at 30 degrees of flexion, the patella is in the trochlear groove
patella is held in place by the retinaculum
lateral retinaculum is stronger than medial retinaculum

15. patella baja - low riding patella; more prone to fat pad irritaiton & tendonitis; injuries tend to be overuse injuries

16. patella alta - high riding patella; more prone to dislocation

17. Why patella dislocation happens laterally ?
weak VMO
shallow trochlear groove
small or abnormal patella
increased Q-angle
tight IT band
tight lateral retinaculum

19. Chondromalacia Patella

20. LIGAMENTS
ALL STATIC STABILIZERS

21. MCL - Medial Collateral Ligament
Injured by valgus force
Connects Femur to Tibia
2 parts
Deep
close to bones; thin layer
thickening of joint capsule, intracapsular
injury causes effusion (joint swelling)
attaches to the medial meniscus
Superficial
forms the MCL
palpable
extracapsular
injury causes edema (swelling outside the joint)

22. Increased Valgus

24. LCL - Lateral Collateral Ligament
Lateral Side
Narrow cord-like band of tissue
Connects femur to head of fibula
does NOT attach to lateral
meniscus
very palpable

25. Collateral Ligament Ruptures
3 degrees of sprains (ligament damage)
Complete tear = 3rd degree sprain

26. ACL - Anterior Cruciate Ligament
attaches on tibia and lateral femoral condyle (medial aspect)
Front of tibia to back of femur
injury happens by anterior blow to femur or deceleration with rotation
prevents the tibia from moving anteriorly
Main stabilizer
Most common ligament to be injured in the knee

27. ACL More commonly torn in girls Surgery
Less muscle, hormones, Q- angle
Surgery
Cadaver graph, patellar tendon, hamstring tendon
About 6-9 months to return to activity

29. Healthy ACL

30. Torn ACL

31. PCL - Posterior Cruciate Ligament
attaches on tibia and medial femoral condyle (lateral aspect)
Prevents tibia from posterior translation
Prevents hyperextension
injury happens by anterior blow to
tibia or posterior blow to femur
PCL

33. Ligament Structures

34. MENISCUS curved, wedged, fibrocartilaginous discs
lies between the femoral condyles and tibial plateaus
the outer edge is thicker than the inner edge
Medial Mensicus
Lateral Meniscus

35. the inner 2/3 of menisci are avascular (no blood supply)
the outer 1/3 is called the "red zone" because it is highly vascular (has blood supply)
reasons for having the menisci
enhance stability of knee
assist with knee motion by decreasing friction
shock absorber

36. Menisectomy - removal of the meniscus
the lateral and medial meniscus are connected by the transverse ligament located in front of the tibial spine
Medial meniscus - "C" shaped
Lateral meniscus - "O" shaped
Medial meniscus is larger than lateral meniscus
Medial meniscus is attached to entire periphery (outer edge), and intrachonduloar eminence (tibial spine), which is also the attachment for the ACL
Lateral meniscus is loosely attached

37. Meniscal Tears Bucket Handle Peripheral Tear Avascular Tear
occurs in the middle of the meniscus (red-white zone)
often times posterior
most common
Peripheral Tear
red zone
responds extremely well to surgery
Avascular Tear
white zone
must be removed and cleaned up on the edges
heals poorly because no blood supply

40. Quadriceps and Patellar Tendons
Quadriceps Tendon
All 4 muscles come together at patella
Patellar Tendon
From inferior patella to tibial tuberosity

41. Quadriceps Anterior Thigh Musculature Four Muscles: Rectus Femoris
Vastus Lateralis
Vastus Medialis
Vastus Intermedius
Extend the Knee

42. Rectus Femoris 2 Joint Muscle Crosses hip and knee Flexes Hip
Extend the knee
Converges with rest of quadriceps muscles at tibial tubercle

43. Hamstrings Three Muscles Common Origin the ischial tuberosity
Semimembranosus
Semitendinosus
Biceps Femoris
Common Origin the ischial tuberosity
Flex the Knee

44. Hamstrings

45. Patella Femoral Assessment

46. Patella Femoral Joint Reaction Force (PFJRF)
As the knee increases in flexion, the PFJRF increases
The reaction force through the patella is from the increased pull on the patella tendon and the quadriceps muscle
As knee flexion increases the angle between the quad and the patella tendon decrease creating more force in the joint

47. Increased weight distribution in the patella
Level walking 0.5 x body weight
Stair climbing 3-4 x body weight
Squatting 7-8 x body weight
****proper lifting techniques decrease the stress on the patella and the knee joint

48. Symptoms of Patella Femoral Pain
Diffuse ache on the anterior knee
Pain with stair climbing
“moviegoers” knee
crepitus (clicking/popping)
giving away
swelling
locking, catching

49. Mechanics of Patella Femoral Joint
Patella functions to increase quad control
During 1st 20 degrees of flexion, the tibia derotates (internal rotation) and the patella is drawn into the trochlear groove
Tibial derotation causes a decrease in the Q-Angle

50. Mechanics of Patella Femoral Joint
Patella stays in trochlear groove ~ 90 degrees and then moves laterally
In full flexion, the lateral femoral condyle is covered by the patella
The ability of the patella to track properly in the groove is dependant upon the bony structures and the balance of forces of soft tissue

51. Mechanics of Patella Femoral Joint
Lateral forces are resisted by
Medial Retinaculum
Vastus Medialis Oblique (VMO)
Lateral forced aided by
Q-Angle
Lateral Retinaculum (3-4 x stronger than medial)
Iliotibial (IT) Band
Vastus Lateralis
The only medial stabilizer is the VMO
It is active through the full ROM
VMO & VL need to have 1:1 Ratio for proper knee function

52. Patella Malalignments

54. Palpations

55. Medial and Lateral Tibial Condyle

56. Medial and Lateral Tibial Condyles & Epicondyles

57. Tibial Tuberosity

58. Fibular Head

59. Quadriceps

60. Bursa

61. Medial and Lateral Joint line

62. Medial Collateral Ligament

63. Pes Anserine

64. Biceps Femoris, Semitendinosus, Semimembranosus

65. Lateral Collateral Ligament

66. IT Band

67. Popliteal fossa

68. Gastrocnemius