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Chapter 15 Knee Conditions

Chapter 15 Knee Conditions. Knee Anatomy. Structure of the knee. A. Anterior view. B. Posterior view. Knee Anatomy (cont’d). Structures of the knee. C. Lateral view. D. Medial view. Knee Anatomy (cont’d). Structures of the knee. E. Superior surface of the tibia. F. Bursa of the knee.

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Chapter 15 Knee Conditions

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  1. Chapter 15 Knee Conditions

  2. Knee Anatomy Structure of the knee. A. Anterior view. B. Posterior view

  3. Knee Anatomy (cont’d) Structures of the knee. C. Lateral view. D. Medial view

  4. Knee Anatomy (cont’d) Structures of the knee. E. Superior surface of the tibia. F. Bursa of the knee

  5. Knee Anatomy (cont’d) • Tibiofemoral Joint • Condyles of femur with plateaus of tibia • Hinge joint—flexion/extension • Tibia does rotate laterally on femur during last few degrees of extension • “Screwing-home mechanism” • Produces a locking of the knee in final degrees during extension

  6. Knee Anatomy (cont’d) • Meniscus • Fibrocartilaginous discs attached to tibial plateaus • Medial and lateral E. Superior surface of the tibia

  7. Knee Anatomy (cont’d) • Meniscus (cont’d) • Functions: • Stabilize joint by deepening the articulation • Shock absorption • Provide lubrication and nourishment • Improve weight distribution • Medial meniscus has an attachment to the MCL and semimembranosus

  8. Joint Capsule and Bursae • Articular capsule – encompasses both tibiofemoral and patellofemoral joints • Bursa inside the capsule • Suprapatellar bursa • Subpopliteal bursa • Semimembranosus bursa

  9. Joint Capsule and Bursae • Bursa outside capsule • Prepatellar bursa • Superficial infrapatellar bursa • Deep infrapatellar bursa F. Bursa at the knee

  10. Ligaments • ACL • Prevents: • Anterior translation of tibia on femur • Rotation of tibia on femur • Hyperextension • PCL • Resists posterior displacement of tibia on femur

  11. Ligaments (cont’d) • MCL • Resist medially directed (valgus) forces • LCL • Resist laterally directed (varus) forces • A. Anterior view. B. Posterior view

  12. Patellofemoral Joint • Patella • Superior, middle, and inferior articular surfaces • Functions • Protect femur • Increase effective power of quadriceps

  13. Patellofemoral Joint (cont’d) Patella. A. Anterior view. B. Posterior view

  14. Q-Angle • Q-angle • Angle between line of resultant force produced byquadriceps and line of patellar tendon • Males 13°; females 18° •  Q-angle— lateral patellofemoral contact  Q-angle— medial tibiofemoral contact

  15. Q-Angle (cont’d)

  16. Nerves • Tibial nerve • Hamstrings except short head of biceps • Common peroneal • Short head of biceps • Femoral • Quadriceps

  17. Nerves (cont’d) Innervation of the knee. A. Anterior view. B. Posterior view

  18. Blood Supply Collateral circulation around the knee. A. Anterior. B. Posterior. C. Circulation to meniscus • Femoral artery • Popliteal artery • Genicular arteries

  19. Kinematics and Major Muscle Actions • Knee flexion • Hamstrings • Assisted by: • Popliteus • Gastrocnemius • Gracilis • Sartorius Motions at the knee. A. Flexion and extension

  20. Kinematics and Major Muscle Actions (cont’d) • Knee extension • Quadriceps femoris muscle group • Rectus femoris • Vastus lateralis • Vastus intermedius • Vastus medialis • Vastus medialis oblique (VMO)

  21. Kinematics and Major Muscle Actions (cont’d) • Knee extension (cont’d) • Screw-home motion • Rotation and passive abduction and adduction • Capability maximal at approximately 90° of knee flexion

  22. Kinematics and Major Muscle Actions (cont’d) • Patellofemoral joint motion • During knee flexion and extension, patella glides in the trochlear groove • Tracking is dependent on the direction of the net force produced by the attached quadriceps

  23. Prevention of Knee Injuries • Physical conditioning • Strength • Flexibility • Rule changes • Footwear • Cleats vs. flat sole • Position of cleats and size

  24. Contusions • Knee • MOI: compression • S&S • Localized tenderness • Pain • Swelling • Management: standard acute; extreme point tenderness physician referral • Caution: excessive swelling could mask other injuries

  25. Contusions (cont’d) • Infrapatellar fat pad • Entrapped between the femur and tibia • S&S • Locking, catching, giving way • Palpable pain on either side of patellar tendon • Extreme pain on forced extension

  26. Contusions (cont’d) • Infrapatellar fat pad (cont’d) • Management • Standard acute • If symptoms persist > 2-3 days, physician referral • Protect the area during activity

  27. Contusions (cont’d) • Peroneal nerve • MOI: blow to the posterolateral aspect of the knee • S&S • Radiating pain down lateral aspect of leg and foot

  28. Contusions (cont’d) • Peroneal nerve (cont’d) • S&S (cont’d) • Severe cases • Initial pain—not immediately followed by tingling or numbness • As swelling ↑ within nerve sheath • Weakness in dorsiflexion or eversion

  29. Contusions (cont’d) • Peroneal nerve (cont’d) • S&S (cont’d) • Severe cases • As swelling ↑ within nerve sheath • Loss of sensation in dorsum of foot, especially between 1st and 2nd toes • May progressively occur days or weeks later

  30. Contusions (cont’d) • Peroneal nerve (cont’d) • Management: • Standard acute, but caution with compression • Severe S&S—immediate physician referral

  31. Bursitis • Prepatellar • MOI • Acute: direct blow to anterior patella • Chronic: repetitive blows • S&S • Swelling • Pain with direct pressure • Pain with passive knee flexion • Localized swelling

  32. Bursitis (cont’d) • Pes anserine • MOI: • Friction between tendon and MCL • Direct trauma • S&S • Pain with knee flexion

  33. Bursitis (cont’d) •  Infrapatellar • Mechanism: • Friction between patellar tendon and fat pad/tibia • May be associated with patellar tendinitis

  34. Bursitis (cont’d) • Infrapatellar (cont’d) • S&S • Point tender with possible swelling posterior to patellar tendon •  pain at end range of resisted knee extension and passive flexion • Prolonged knee flexion may  symptoms

  35. Bursitis (cont’d) • Bursitis management • Standard acute;  aggravating activities or total rest • Protect area during activity

  36. Ligamentous Conditions • AAOS classifies ligamentous knee injuries according to: • Functional disruption of a specific ligament • Amount of laxity • Direction of laxity • Direction divides laxity into 4 straight and 4 rotatory laxities • Knowing knee position at impact and direction the tibia displaces or rotates indicates the damaged structures

  37. Ligamentous Conditions (cont’d) Knee instability

  38. Ligamentous Conditions (cont’d) Knee instability

  39. Ligamentous Conditions (cont’d) • Straight medial laxity (valgus laxity) • Involves MCL; posterior medial capsule—possibly PCL • Lateral forces cause tension on medial aspect of knee

  40. Ligamentous Conditions (cont’d) • Straight medial laxity (valgus laxity) (cont’d) • 1st degree • Mild pain medial joint line • Little or no joint effusion/mild swelling at site • Full ROM with minor discomfort • Valgus @ 0°—stable; @ 30º—+

  41. Ligamentous Conditions (cont’d) • Straight medial laxity (valgus laxity) (cont’d) • 2nd or 3rd degree • Unable to fully extend the leg; often walk on the ball of foot; unable to keep heel flat on the ground

  42. Ligamentous Conditions (cont’d) • Straight lateral laxity (varus laxity) • Involves LCL, lateral capsular ligaments, PCL • Medial forces produce tension on lateral aspect of knee • Not usually isolated—presence of IT band, biceps femoris, popliteus

  43. Ligamentous Conditions (cont’d) • Straight lateral laxity (varus laxity) (cont’d) • S&S • Similar to MCL • Swelling minimal—no attachment to capsule • Instability may not be obvious if other stabilizers are intact

  44. Ligamentous Conditions (cont’d) • Straight anterior laxity (anterior instability) • Anterior displacement of tibia on femur • Involves ACL—rarely isolated • MOI: cutting or turning maneuver, landing, or sudden deceleration

  45. Ligamentous Conditions (cont’d) • Straight anterior laxity (anterior instability) (cont’d) • S&S • Pain • Minimal and transient to severe and lasting • Deep in knee difficult to pinpoint • “Pop” • Effusion within 3 hours; reports knee giving way—does not feel right

  46. Ligamentous Conditions (cont’d) • Straight posterior laxity • Tibia displaced posteriorly • Involves PCL • MOI • Hyperextension force • Fall on flexed knee (initial contact at tibial tuberosity)

  47. Ligamentous Conditions (cont’d) • Straight posterior laxity (cont’d) • S&S • Sense of stretching to posterior knee • “Pop” • Rapid joint effusion • ↓ knee flexion due to effusion

  48. Ligamentous Conditions (cont’d) • Management • Standard acute • Unable to walk normally – crutches should be used • Physician referral • Not typically an ER, but seen by physician 1-2 post-injury

  49. Knee Dislocation/Subluxation • Minimum of 3 ligaments torn for knee to dislocate • Most often—ACL, PCL, and one collateral ligament • Concern: damage to other structures; especially neurovascular • MOI: cutting, twisting, or pivoting maneuver

  50. Knee Dislocation/Subluxation (cont’d) • S&S • Individual describes severe injury • “Pop” • Deformity (unless spontaneously reduced) • Management: standard acute • Spontaneous reduction—physician referral • Not reduced—activate emergency plan, including summoning EMS

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