Chapter 20: The Knee and Related Structures

1. Chapter 20: The Knee and Related Structures Jennifer Doherty-Restrepo, MS, LAT, ATC Academic Program Director, Entry-Level ATEP Florida International University Acute Care and Injury Prevention

9. Functional Anatomy • Movement of the knee requires flexion, extension, rotation and the arthrokinematic motions of rolling and gliding • Rotational component involves the “screw home mechanism” • As the knee extends it externally rotates because the medial femoral condyle is larger than the lateral • Provides increased stability to the knee

10. Capsular ligaments • Taut during full extension and relaxed with flexion • Allows rotation to occur • Deeper capsular ligaments remain taut to keep rotation in check • PCL prevents excessive internal rotation, guides the knee in flexion, and acts as drag during initial glide phase of flexion • ACL stops excessive internal rotation, stabilizes the knee in full extension, and prevents hyperextension

11. Patella • Aids knee during extension, providing a mechanical advantage • Distributes compressive stress on the femur by increasing contact between patellar tendon and femur • Protects patellar tendon against friction • When moving from extension to flexion the patella glides laterally and further into trochlear groove

12. Kinetic Chain • Directly affected by motions and forces occurring at the foot, ankle, lower leg, thigh, hip, pelvis, and spine • With the kinetic chain, forces must be absorbed and distributed • If body is unable to manage the imposed forces, breakdown in the kinetic chain occurs • Knee is very susceptible to injury resulting from the absorption of forces

13. Assessment of the Knee Joint • Determine MOI - This is critical!!! • History: Acute Injury • Past history • Position of body at time of injury? • Did the knee collapse? • Did you hear or feel anything? • Could you move your knee immediately after injury or was it locked? • Did swelling occur? • Where was the pain

14. History: Recurrent or Chronic Injury • What is your major complaint? • When did you first notice the condition? • Is there recurrent swelling? • Does the knee lock or catch? • Is there severe pain? • Grinding or grating? • Does it ever feel like giving way? • What does it feel like when ascending and descending stairs? • What past treatment have you undergone?

15. Observation • Walking, half squatting, going up and down stairs • Swelling, ecchymosis • Leg alignment • Genu valgum and genu varum • Hyperextension and hyperflexion • Patella alta and baja • Patella rotated inward or outward • Tibial torsion, femoral anteversion and retroversion

16. Tibial torsion • An angle that measures less than 15 degrees is an indication of tibial torsion Femoral Anteversion and Retroversion • Total rotation of the hip equals ~100 degrees • If the hip rotates >70 degrees internally, anteversion of the hip may exist

18. Observation cont. • Knee Symmetry or Asymmetry • Do the knees look symmetrical? • Is there obvious swelling? • Atrophy? • Leg Length Discrepancy • Anatomical or functional • Anatomical differences can potentially cause problems in all weight bearing joints • Functional differences can be caused by pelvic rotations or mal-alignment of the spine

19. Medial tibial plateau Medial femoral condyle Adductor tubercle Gerdy’s tubercle Lateral tibial plateau Lateral femoral condyle Lateral epicondyle Head of fibula Tibial tuberosity Superior and inferior patella borders (base and apex) Around the periphery of the knee relaxed, in full flexion and extension Palpation - Bony

20. Vastus medialis Vastus lateralis Vastus intermedius Rectus femoris Quadriceps and patellar tendon Sartorius Medial patellar plica Anterior joint capsule Iliotibial Band Arcuate complex Medial and lateral collateral ligaments Pes anserine Medial/lateral joint capsule Semitendinosus Semimembranosus Gastrocnemius Popliteus Biceps Femoris Palpation - Soft Tissue

21. Palpation - Swelling • Intracapsular swelling • May be referred to as joint effusion • Swelling within the joint that is caused by synovial fluid and blood is called hemarthrosis • Sweep maneuver – sign of joint effusion • Ballotable patella - sign of joint effusion • Extracapsular swelling • Localized over the injured structure • May ultimately migrate down to foot and ankle

22. Special Tests: Knee Instability • Valgus Stress Test • Used to assess the integrity of MCL • Testing at 0 degrees incorporates capsular testing • Testing at 30 degrees of flexion isolates the ligaments

23. Special Tests: Knee Instability • Varus Stress Test • Used to assess the integrity of LCL • Testing at 0 degrees incorporates capsular testing • Testing at 30 degrees of flexion isolates the ligaments

24. Special Tests: Knee Instability Anterior Cruciate Ligament Tests • Drawer test at 90 degrees of flexion • Tibia sliding forward from under the femur is considered a positive sign • Should be performed with knee internally and externally rotated to test integrity of joint capsule

25. Special Tests: Knee Instability Anterior Cruciate Ligament Tests • Lachman Drawer Test • Avoids painful flexion immediately after injury • Reduces hamstring involvement • At 30 degrees of flexion an attempt is made to translate the tibia anteriorly on the femur • A positive test indicates damage to the ACL

26. Variations for the Lachman Drawer Test • May be necessary if athlete is large or examiner’s hands are small • Variations include: • Rolled towel under the femur • Leg off the table with athlete supine • Athlete prone on table with knee and lower leg just off table

27. Special Tests: Knee Instability • Pivot Shift Test • Used to determine anterolateral rotary instability • Position starts with knee extended and leg internally rotated • The thigh and knee are then flexed with a valgus stress applied to the knee • Reduction of the tibial plateau (producing a clunk) is a positive sign

28. Special Tests: Knee Instability • Jerk Test • Reverses direction of the pivot shift • Moves from position of flexion to extension • Without an ACL the tibia will sublux at 20 degrees of flexion

29. Special Tests: Knee Instability • Flexion-Rotation Drawer Test • Knee is taken from a position of 15 degrees of flexion • Tibia is subluxed anteriorly with femur externally rotated • Knee is moved into 30 degrees of flexion where tibia rotates posteriorly and femur internally rotates

30. Special Tests: Knee Instability Posterior Cruciate Ligament Tests • Posterior Drawer Test • Knee is flexed at 90 degrees and a posterior force is applied to determine translation of the tibia posteriorly • Positive sign indicates a PCL deficient knee

31. Special Tests: Knee Instability Posterior Cruciate Ligament Tests • External Rotation Recurvatum Test • With the athlete supine, the leg is lifted by the great toe • If the tibia externally rotates and slides posteriorly there may be a PCL injury and damage to the posterolateral corner of the capsule

32. Special Tests: Knee Instability • Posterior Sag Test (Godfrey’s test) • Athlete is supine with both knees flexed to 90 degrees • Lateral observation is required to determine extent of posterior sag while comparing bilaterally

33. Instrument Assessment of the Cruciate Ligaments • A number of devices are available to quantify AP displacement of the knee • KT-2000 arthrometer • Stryker knee laxity tester • Genucom • Test can be taken pre & post-operatively and throughout rehabilitation

34. Special Tests: Meniscal Tests • McMurray’s Meniscal Test • Used to determine displaced meniscal tear • Leg is moved into flexion and extension while knee is internally and externally rotated in conjunction with valgus and varus stresses • A positive test is found when clicking and popping are felt

36. Special Tests: Meniscal Tests • Apley’s Compression Test • Hard downward pressure is applied with rotation of the tibia • Pain indicates a meniscal injury

37. Special Tests: Meniscal Tests • Apley’s Distraction Test • Traction is applied with rotation of the tibia • Pain will occur if there is damage to the capsule or ligaments • No pain will occur if there is a meniscal injury

38. Other Special Tests • Girth Measurements • Changes in girth may result due to atrophy, swelling, and conditioning • Circumferential measures to determine deficits and gains during rehabilitation • Subjective Ratings • Used to determine patient’s perception of pain, stability, and functional performance

39. Other Special Tests • Functional Examination • Assess walking, running, turning, cutting, etc • Co-contraction test, vertical jump, single leg hop tests, and the duck walk • Resistive strength testing

40. Other Special Tests • The Q - Angle • Line which bisect the patella relative to the ASIS and the tibial tubercle • Normal angle is 10° for males and 15 ° for females • Elevated angles often lead to pathological conditions associated with improper patella tracking • The A - Angle • Patellar orientation relative to the tibial tubercle • Quantitative measure of the patellar realignment after rehabilitation • An angle greater than 35° is often correlated associated with patellofemoral pathomechanics

41. Special Tests: Patella • Patella Grinding Test • Determines integrity of patellar cartilage on the undersurface of patella • Patella Compression Test • Determines integrity of patellar cartilage on the undersurface of patella • Apprehension Tests • Patella pushed laterally to determine presence of subluxation/dislocation

42. Recognition and Management of Specific Injuries

43. Medial Collateral Ligament Sprain • MOI = severe blow or outward twist • Grade I: Signs and Symptoms • Little fiber tearing or stretching • Stable valgus test • Little or no joint effusion • Some joint stiffness and point tenderness on lateral aspect of the knee • Relatively normal ROM

44. Grade I: Management • RICE for 24 hours • Crutches if necessary • Rehab • Cryokinetics • Isometrics • Progress to SLRs, bicycle riding, and isokinetics • Return to play when all areas have returned to normal • May require 3 weeks to recover

45. Grade II: Signs and Symptoms • Complete tear of deep capsular ligament and partial tear of MCL • No gross instability; laxity at 5-15 degrees of flexion • Slight swelling • Moderate to severe joint tightness • Decreased ROM • Pain along medial aspect of knee

46. Grade II: Management • RICE for 48-72 hours • Crutch use until acute inflammation phase has resolved • Possibly a brace or casting prior to the initiation of ROM activities • Modalities 2-3 times daily for pain • Gradual progression from isometrics (quad exercises) to CKC exercises; functional progression activities

47. Grade III: Signs and Symptoms • Complete tear of supporting ligaments • Complete loss of medial stability • Minimum to moderate swelling • Immediate pain followed by ache • Loss of motion due to effusion and hamstring guarding • Positive valgus stress test

48. Grade III: Management • RICE • Conservative non-operative versus surgical approach • Limited immobilization (with a brace) • Progressive weight bearing and increased ROM over 4-6 week period • Rehab would be similar to Grade I & II injuries

49. Lateral Collateral Ligament Sprain • MOI = Varus force usually with the tibia internally rotated • Direct blow is rare MOI • If severe enough damage may also occur to • Cruciate ligaments • ITB • Meniscus • Bony fragments may result as well

50. Signs and Symptoms • Pain and tenderness over LCL • Swelling and effusion around the LCL • Joint laxity with varus testing • May cause irritation of the peroneal nerve • Management • Same as MCL injury management