1. The Knee: Anatomy and Injuries Sports Medicine
Lesson 2: Understanding Athletic-Related Injuries to the Lower Extremity
The Knee: Anatomy and Injuries
Sports Medicine

2. Knee

3. Mechanics of the Knee Hinge Joint Knee movement
Flexion
Extension
Slight Rotation
Gliding
Knee stability depends on ligaments, joint capsule, and muscles.

4. Joint Capsule

5. Bones of the Knee (Femur)
Medial and lateral condyles (bumps or knobs)
Medial condyle is longer than the lateral condyle.
Trochlea – groove that receives the patella.
Articular (joint) cartilage

6. Tibia
Tibial plateau
Tibial plateau (flat spot) has two shallow dips that match up with the medial and lateral condyles.
Main weight bearing bone (95 – 97%).

7. Tibial Plateau

8. Patella Moves in the groove between the femoral condyles (bumps).
Provides a better line of pull for the quadriceps muscles.

9. Fibula Main purpose is ligament and muscle attachment.
Non – Weight bearing bone.
Located on lateral side of the leg.
Minimal knee function.

10. Ligaments of the Knee
ACL
PCL
MCL
LCL

11. Anterior Cruciate Ligament (ACL)
Attachment: femur –lateral condyle.
Attachment: Tibia – Anterior tibial plateau.
Prevents excessive anterior movement and internal rotation of the tibia.
Most likely to be injured!!

12. ACL Extension / Tight Flexion / Relaxed Very vascular
Usually surgically replaced if torn.

13. Posterior Cruciate Ligament (PCL)
Attachment: Femur -medial condyle.
Tibia –tibial plateau.
Prevents excessive posterior movement of the tibia on the femur.
Prevents hyperextension of the knee

14. Medial Collateral Ligament (MCL)
Attachment: Femur – superior epicondyle.
Tibia – Medial aspect / medial meniscus.
Resists valgus forces. (inward bending)
Resists external rotation of the tibia.

15. Lateral Collateral Ligament (LCL)
Attachment: Femur – lateral epicondyle.
Fibula: Fibular head
Resists varus forces (outward bending) which causes “bowed legs”

16. Meniscus Medial (C- shape) and lateral (O-shape) meniscus.
Located on tibial plateau.
Primary function – shock absorber.
Increase surface contact.
Helps stabilize knee

17. Meniscus

18. Bursa's of the Knee Bursa’s are fluid filled sac’s .
Reduce friction between anatomical structures.
Two dozen bursa’s within the knee.
Prepatellar most often injured.

19. Bursa's of the Knee

20. Muscles of the Knee

21. Quadricep Muscle Group

22. Quadriceps Extensors of the knee. Stabilizers of the knee.
Made up of 4 muscles (quad = four)
Vastus medialis (VMO) – important for patellar tracking.
Vastus intermedialis
Vastus Lateralis
Rectus femoris – Knee extension / Hip flexion.

23. Patellar Tendon
Patellar Tendon –tendon shared by the quadriceps muscle group.
The patella is located in it.

24. Hamstring Muscle Group

25. Hamstrings Flexors of the knee. Extensors of the hip.
Prevents anterior tibial movement / Aids ACL.

26. IT - Band Lateral side of leg. Important in the knee
Assist LCL in the lateral stability of the knee.

27. IT band in need of “rolling
IT band in need of “rolling.” Process by which we stretch and loosen up the ligament.
Inflammation of the IT band causes pain in the lateral knee.

28. I-T Band Friction

29. Meniscus Injuries Mechanism – Compression and rotation femur / tibia.
Can be associated with ligament injury (MCL).

30. Meniscus injuries Signs & Symptoms - Joint Swelling
- Clicking or locking.
- Loss of ROM (range of motion)
- Diagnosis is often difficult.

31. Meniscus MRI

32. Treatment Surgical treatment
- Procedure depends on location and severity of tear.
- Resection (Total removal of tear)
- Stitch or tack.

34. Non Surgical Treatment
- Indicated only for minor tears.
- RICE (Control Swelling)
- Maintain ROM / Strength
- Non surgical treatment can result in further damage

35. ACL Injuries Common in sports.
Mechanism – External rotation of tibia, knee in valgus position, foot fixed.
Signs & Symptoms
Feeling pop
Knee feels unstable
Joint swelling

36. Non Surgical Treatment
RICE (Control Swelling)
Immobilizer / Crutches
Refer to physician
Rehabilitation (Strengthening & ROM)

37. MRI of ACL
NORMAL ACL
ACL TEAR

38. Surgical Treatment Arthroscopic surgery
Various grafts can be used for repair.
Patellar tendon (Autograft)
Hamstring (semitendinosus / Gracillis)
Cadaver (Allograft)
Surgical Treatment

43. Patellar Tendon (autograft)

47. PCL Injuries Injured less frequent Mechanism:
- Fall on anterior aspect of bent knee with foot plantar flexed.
- Hyperextension

48. MCL / LCL Injuries
MCL injuries are usually caused by a lateral to medial blow to the knee. Also known as a valgus force.
LCL injuries are usually caused by medial to lateral blow to the knee. Also known as a varus force.

49. MCL Injuries Mechanism of Injury
- direct blow from the lateral side (Valgus Stress)
- severe rotation of the tibia
- can be a combination of both

50. MRI OF MCL TEAR

51. MCL Sprains 1st degree - ligamentous fibers are stretched
- joint is stable during valgus stress test
- little or no joint effusion
- may be some joint stiffness and medial joint line tenderness
- almost full range of motion

52. MCL Sprains 2nd degree sprain - partial tear of the ligament
- slight to moderate laxity during valgus stress test
- there is little joint effusion
- moderate to severe joint stiffness with loss of ROM

53. MCL Sprains 3rd degree sprain - Complete tear
- severe laxity revealed with valgus stress test
- moderate joint effusion
- loss of ROM

54. Treatment of Knee Sprains
1st degree – RICE, Rehab to increase strength, ROM.
2nd degree – RICE, Immobilize, Crutch, 24 hours. Re-evaluate. Refer to physician
3rd degree – RICE, Immobilize, Crutch. Refer to physician

55. LCL Injuries Not very common in athletics.
Occurs by a medial blow to knee which produces a varus stress

56. Patellar Dislocation

57. Knee Dislocation

58. Knee Dislocation

60. Prevention of Knee Injuries
To avoid injuries to the knee, the athlete must be as highly conditioned as possible, which means total body conditioning that includes strength, flexibility, cardiovascular and muscle endurance, agility, speed and balance.
THE MUSCLES around the knee MUST be strong and flexible.

61. Prevention of Knee Injuries
Athletes participating in a particular sport should acquire a strength ratio between the quadriceps and hamstring muscle groups. For example: the hamstring muscles of football players should have 60 to 70 percent of the strength of the quadriceps muscles. The gastrocnemius muscle should also be strengthened to help stabilize the knee. Although maximizing muscle strength may prevent some injuries, it fails to prevent twisting injuries.

62. Prevention of Knee Injuries
Shoe Type:
Cleat Length
Astro Turf shoes: more grip=more injuries
Sneakers are good for artificial surfaces

63. Functional and Prophylactic Knee Braces
Functional Knee Braces are used to protect grade 1 and 2 sprains of the ACL and MCL, and reconstructed ACL knees. Most of them are bilateral knee braces, meaning there is a hinge on both sides of the brace. These braces have an important part within the athletic community. They will also give the athlete confidence while playing.

64. Knee Injury Treatments
Side Leg Raises

65. Knee Injury Treatments
Side Leg Raises

66. Knee Injury Treatments
Terminal Knee Extensions

67. Knee Injury Treatments
Step Ups

68. BOSU