The Knee: Anatomy and Injuries

1. The Knee: Anatomy and Injuries

3. 2 Joints at the Knee • Tibiofemoral Joint – formed between the femur (femoral condyles), and the tibial plateau A HINGE JOINT • Patellofemoral joint – formed between the patella and the femur A GLIDING JOINT

5. Femur proximal – head and neck of femur, greater trochanter distal – medial and lateral condyles and epicondyles Skeletal Anatomy

6. Patella – largest sesamoid bone in body Tibia – tibial plateau forms knee joint with femur The fibula is not a part of the knee joint

8. Muscles that move the knee and thigh • The Quadriceps – Knee Extension 1. Vastus Medialis 2. Vastus Lateralis 3. Vastus Intermedius 4. Rectus Femoris – 2 joint muscle that also acts as a hip flexor

10. The Hamstrings- knee flexion 3 muscles: 1. Biceps Femoris 2. Semimembranosus 3. Semitendinosus

12. The Adductors (Groin) Adduct the thigh 1. Adductor Longus 2. Adductor Magnus 3. Adductor Brevis 4. Gracilis

14. The Sartorius: - flexes, abducts, and laterally rotates thigh - longest muscle in the body, “tailor’s muscle” - Crosses hip and knee joint

16. The Iliotibial Tract (IT Band) - neither a muscle or tendon, but a long, thick band of tissue that inserts into the lateral tibia (Gerdy’s Tubercle)

18. The Major Knee Ligaments • ACL – Anterior Cruciate Ligament • PCL – Posterior Cruciate Ligament • MCL – Medial Collateral Ligament • LCL – Lateral Collateral Ligament

19. ACL Runs from posterior femur to anterior tibia Prevents anterior displacement of tibia PCL Runs from anterior femur to posterior tibia Prevents posterior displacement of tibia The Cruciate LigamentsThe major stabilizing ligaments of the knee

22. MCL: Medial Collateral Ligament Runs from medial femur to medial tibia Prevents valgus force LCL: Lateral Collateral Ligament Runs from lateral femur to head of fibula Prevents varus force The Collateral Ligaments

24. The Meniscus A “c”-shaped piece of fibrocartilage located in the knee joint between the femur and attached to the top of the tibia Cartilage = meniscus

27. Medial - larger and more C-shaped - more firmly attached to tibia - has attachments to MCL Lateral - smaller and more round or O-shaped - not firmly attached to tibia and LCL Differences between medial and lateral

28. Blood Supply to the Meniscus • Mostly avascular – little or no blood supply • Only the outer 20% has a blood supply * Does not have the ability to heal itself unless there is a small tear in the outer 20%

29. Functions of Meniscus • Stability • Shock absorption • Lubrication and nutrition • Allows adequate weight distribution

30. Normal Torn

32. Total Knee Joint Replacement • Surgery to replace a painful damaged or diseased knee joint with an artificial joint (prosthesis) • Artificial hip invented 1962 • 1969 – first artificial knee in USA

33. The Knee Surgery • Thin layer of bone removed from femur – thin metal replaces it • Upper layer of tibia replaced with plastic • Back of patella replaced with plastic • Parts fastened with “bone cement”

34. Risks of Knee Joint Replacement • Blood clots in large veins • Infection • Stiffness • Implant Loosening/Failure - more of a problem in younger patients

38. Knee Injuries and Conditions

39. Genu Valgum: “knock knees”

40. Genu Varum: “bowlegs”

41. Genu Recurvatum: hyperextension of the knee joint

42. Patellar Tracking Disorder • When your patella is out of balance or the patellar cartilage is damaged, you can have knee pain while climbing stairs, running, standing up from a bent-knee position, squatting, or even sitting for a period of time. This kind of pain, called anterior knee pain or patellofemoral pain syndrome, is sometimes caused by a common kneecap problem known as patellar tracking disorder.

43. Causes • Quadriceps weakness • Tendon and muscle tightness in the leg, foot, or hip areas • Improper athletic technique or training • A blow to the kneecap • Excessive body weight, which overstresses the knee joint. • Genetics

44. Genetics (cont.) - An excessively long patellar tendon - patellar shape, hip structure, or a shallow femoral groove for the patella to glide along

45. Patellofemoral Disorders • Problems with patella – most common cause of knee pain • Anatomy: - Patella is a sesamoid bone formed in Quad tendon - Patellofemoral joint – patella and femur - Compression forces – <body weight during walking 2.5 x body weight during stairs

46. Patellar Tendonitis • “Jumper’s Knee” • Inflammation and degeneration of the tendon that connects the kneecap (Patella) to the shin bone (Tibia).

48. Chondromalacia • A gradual degenerative change that occurs beneath the patella • Caused by acute trauma, repeated microtrauma, or improper alignment of the patella in the trochlear groove • Weak vastus medialis (VMO) can cause improper alignment • Prevention: strengthen quads Minimize squats, downhill running, biking with low seat

49. Chondromalacia

50. Dislocation usually occurs as a result of sudden direction changes while running and the knee is under stress or it may occur as a direct result of injury. Usually lateral Patellar Dislocation