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Chapter 20: The Knee and Related Structures

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  1. Chapter 20: The Knee and Related Structures © 2011 McGraw-Hill Higher Education. All rights reserved.

  2. Complex joint that endures great amounts of trauma due to extreme amounts of stress that are regularly applied • Hinge joint w/ a rotational component • Stability is due primarily to ligaments, joint capsule and muscles surrounding the joint • Designed for stability w/ weight bearing and mobility in locomotion © 2011 McGraw-Hill Higher Education. All rights reserved.

  3. Figure 20-1 © 2011 McGraw-Hill Higher Education. All rights reserved.

  4. Figure 20-2 © 2011 McGraw-Hill Higher Education. All rights reserved.

  5. Figure 20-3 A-B © 2011 McGraw-Hill Higher Education. All rights reserved.

  6. Figure 20-3 C © 2011 McGraw-Hill Higher Education. All rights reserved.

  7. Figure 20-4 © 2011 McGraw-Hill Higher Education. All rights reserved.

  8. Figure 20-5 A & B © 2011 McGraw-Hill Higher Education. All rights reserved.

  9. Figure 20-5C © 2011 McGraw-Hill Higher Education. All rights reserved.

  10. Figure 20-6 © 2011 McGraw-Hill Higher Education. All rights reserved.

  11. Figure 20-7 © 2011 McGraw-Hill Higher Education. All rights reserved.

  12. 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 • Popliteus “unlocks” knee allowing knee to flex © 2011 McGraw-Hill Higher Education. All rights reserved.

  13. Capsular ligaments are taut during full extension and relaxed w/ flexion • Allows rotation to occur • Deeper capsular ligaments remain taut to keep rotation in check • PCL prevents excessive internal rotation, limits anterior translation and posterior translation when tibia is fixed and non-weight bearing, respectively • ACL stops excessive internal rotation, stabilizes the knee in full extension and prevents hyperextension © 2011 McGraw-Hill Higher Education. All rights reserved.

  14. Range of motion includes 140 degrees of motion • Limited by shortened position of hamstrings, bulk of hamstrings and extensibility of quads • 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 © 2011 McGraw-Hill Higher Education. All rights reserved.

  15. 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 forces, breakdown to the system occurs • Knee is very susceptible to injury resulting from absorption of forces © 2011 McGraw-Hill Higher Education. All rights reserved.

  16. Assessing the Knee Joint • Determining the mechanism of injury is critical • History- Current Injury • Past history • Mechanism- what position was your body in? • 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 © 2011 McGraw-Hill Higher Education. All rights reserved.

  17. 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? © 2011 McGraw-Hill Higher Education. All rights reserved.

  18. 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 • May cause a combination of problems • Tibial torsion, femoral anteversion and retroversion © 2011 McGraw-Hill Higher Education. All rights reserved.

  19. Figure 20-10 & 11 © 2011 McGraw-Hill Higher Education. All rights reserved.

  20. Figure 20-12 & 13 © 2011 McGraw-Hill Higher Education. All rights reserved.

  21. 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 Figure 20-9 © 2011 McGraw-Hill Higher Education. All rights reserved.

  22. Figure 20-14 © 2011 McGraw-Hill Higher Education. All rights reserved.

  23. 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 © 2011 McGraw-Hill Higher Education. All rights reserved.

  24. Palpation - Bony Medial tibial plateau Medial femoral condyle Adductor tubercle Gerdy’s tubercle Lateral tibial plateau Lateral femoral condyle Lateral epicondyle Medial epicondyle Head of fibula Tibial tuberosity Patella Superior and inferior patella borders (base and apex) Around the periphery of the knee relaxed, in full flexion and extension © 2011 McGraw-Hill Higher Education. All rights reserved.

  25. Palpation - Soft Tissue Vastus medialis Vastus lateralis 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 © 2011 McGraw-Hill Higher Education. All rights reserved.

  26. Palpation of Swelling • Intra vs. extracapsular swelling • Intracapsular may be referred to as joint effusion • Swelling w/in the joint that is caused by synovial fluid and blood is a hemarthrosis • Sweep maneuver • Ballotable patella - sign of joint effusion • Extracapsular swelling tends to localize over the injured structure • May ultimately migrate down to foot and ankle © 2011 McGraw-Hill Higher Education. All rights reserved.

  27. Special Tests for Knee Instability • Use endpoint feel to determine stability • MRI may also be necessary for assessment • Classification of Joint Instability • Knee laxity includes both straight and rotary instability • Translation (tibial translation) refers to the glide of tibial plateau relative to the femoral condyles • As the damage to stabilization structures increases, laxity and translation also increase © 2011 McGraw-Hill Higher Education. All rights reserved.

  28. Collateral Ligament Stress Tests (Valgus and Varus) Used to assess the integrity of the MCL and LCL respectively Testing at 0 degrees incorporates capsular testing while testing at 30 degrees of flexion isolates the ligaments © 2011 McGraw-Hill Higher Education. All rights reserved.

  29. Anterior Cruciate Ligament Tests • Drawer test at 90 degrees of flexion • Tibia sliding forward from under the femur is considered a positive sign (ACL) • Should be performed w/ knee internally and externally to test integrity of joint capsule Figure 20-18 © 2011 McGraw-Hill Higher Education. All rights reserved.

  30. Lachman Drawer Test Will not force knee into 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 Figure 20-19 © 2011 McGraw-Hill Higher Education. All rights reserved.

  31. A series of variations are also available 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 approach with athlete supine • Athlete prone on table with knee and lower leg just off table © 2011 McGraw-Hill Higher Education. All rights reserved.

  32. Pivot Shift Test Used to determine anterolateral rotary instability Position starts w/ knee extended and leg internally rotated The thigh and knee are then flexed w/ a valgus stress applied to the knee Reduction of the tibial plateau (producing a clunk) is a positive sign Slocum’s test is variation on the pivot shift Figure 20-20 © 2011 McGraw-Hill Higher Education. All rights reserved.

  33. Jerk Test • Reverses direction of the pivot shift • Moves from position of flexion to extension • W/out an ACL the tibia will sublux at 20 degrees of flexion Figure 20-21 © 2011 McGraw-Hill Higher Education. All rights reserved.

  34. Flexion-Rotation Drawer Test • Knee is taken from a position of 15 degrees of flexion (tibia is subluxed anteriorly w/ femur externally rotated) • Knee is moved into 30 degrees of flexion where tibia rotates posteriorly and femur internally rotates Figure 20-22 © 2011 McGraw-Hill Higher Education. All rights reserved.

  35. Losee’s Test • Similar to flexion-reduction drawer test • Performed side-lying • Begins with knee at 45 degrees of flexion and external tibial rotation • Knee is subluxed anteriorly • As the knee is extended it reduces Figure 20-22 © 2011 McGraw-Hill Higher Education. All rights reserved.

  36. Posterior Cruciate Ligament Tests • Posterior Drawer Test • Knee is flexed at 90 degrees and a posterior force is applied to determine translation posteriorly • Positive sign indicates a PCL deficient knee • 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 © 2011 McGraw-Hill Higher Education. All rights reserved.

  37. Posterior Sag Test (Godfrey’s test) Athlete is supine w/ both knees flexed to 90 degrees Lateral observation is required to determine extent of posterior sag while comparing bilaterally Figure 20-25 © 2011 McGraw-Hill Higher Education. All rights reserved.

  38. 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 and Genucom can be used to assess the knee Test can be taken pre & post-operatively and throughout rehabilitation Figure 20-26 © 2011 McGraw-Hill Higher Education. All rights reserved.

  39. Meniscal Tests • McMurray’s Meniscal Test • Used to determine displaceable meniscal tear • Leg is moved into flexion and extension while knee is internally and externally rotated in conjunction w/ valgus and varus stressing • A positive test is found when clicking and popping are felt © 2011 McGraw-Hill Higher Education. All rights reserved.

  40. Figure 20-27 © 2011 McGraw-Hill Higher Education. All rights reserved.

  41. Apley’s Compression Test Hard downward pressure is applied w/ rotation Pain indicates a meniscal injury Apley’s Distraction Test Traction is applied w/ rotation Pain will occur if there is damage to the capsule or ligaments No pain will occur if it is meniscal © 2011 McGraw-Hill Higher Education. All rights reserved.

  42. Thessaly Test • Patient stands on one leg • Tested with knee flexed to 5 degrees and 20 degrees • Patient then rotates trunk and knee into internal and external rotation, with clinician supporting patient • Positive test results in pain along medial or lateral joint line • Perform test on healthy side first for comparison Figure 20-29 © 2011 McGraw-Hill Higher Education. All rights reserved.

  43. Girth Measurements • Changes in girth can occur due to atrophy, swelling and conditioning • Must use circumferential measures to determine deficits and gains during the rehabilitation process • Measurements should be taken at the joint line, the level of the tibial tubercle, belly of the gastrocnemius, 2 cm above the superior border of the patella, and 8-10 cm above the joint line • Subjective Rating • Used to determine patient’s perception of pain, stability and functional performance © 2011 McGraw-Hill Higher Education. All rights reserved.

  44. Patellar Examination • Palpation of the Patella • Must palpate around and under patella to determine points of pain • Patella Grinding, Compression and Apprehension Tests • A series of glides and compressions are performed w/ the patella to determine integrity of patellar cartilage © 2011 McGraw-Hill Higher Education. All rights reserved.

  45. Patella Grinding, Compression and Apprehension Tests © 2011 McGraw-Hill Higher Education. All rights reserved.

  46. Q-Angle • Lines which bisect the patella relative to the ASIS and the tibial tubercle • Normal angle is 10 degrees for males and 15 degrees for females • Elevated angles often lead to pathological conditions associated w/ improper patella tracking • The A - Angle • Patellar orientation to the tibial tubercle • Quantitative measure of the patellar realignment after rehabilitation • An angle greater than 35 degrees is often correlated w/ patellofemoral pathomechanics © 2011 McGraw-Hill Higher Education. All rights reserved.

  47. Functional Examination • Must assess walking, running, turning and cutting • Co-contraction test, vertical jump, single leg hop tests and the duck walk • Resistive strength testing • Tests should be performed at speed w/out limping or favoring injured limb • Use baseline for comparison if available © 2011 McGraw-Hill Higher Education. All rights reserved.

  48. Prevention of Knee Injuries • Physical Conditioning and Rehabilitation • Total body conditioning is required • Strength, flexibility, cardiovascular and muscular endurance, agility, speed and balance • Muscles around joint must be conditioned (flexibility and strength) to maximize stability • Must avoid abnormal muscle action through flexibility • In an effort to prevent injury, extensibility of hamstrings, erector spinae, groin, quadriceps and gastrocnemius is important © 2011 McGraw-Hill Higher Education. All rights reserved.

  49. Decreasing the Risk for ACL Injury • Focus on strength, neuromuscular control, balance • Series of different programs which address balance board training, landing strategies, plyometric training, and single leg performance • Can be implemented in rehabilitation and preventative training programs • Shoe Type • Change in football footwear has drastically reduced the incidence of knee injuries • Shoes w/ more short cleats does not allow foot to become fixed - still allows for control w/ running and cutting © 2011 McGraw-Hill Higher Education. All rights reserved.

  50. Functional and Prophylactic Knee Braces Used to prevent and reduce severity of knee injuries Used to protect MCL, or prevent further damage to grade 1 & 2 sprains of the ACL or to protect the ACL following surgery Can be custom molded and designed to control rotational forces Figure 20-37 © 2011 McGraw-Hill Higher Education. All rights reserved.