Examination of the Knee

Examination Considerations of the Knee

• Objectives: Discuss relevant knee anatomy, pertinent subjective information, proper examination techniques, and pathological considerations.
• Subjective – Mechanism of Injury: Distinguish between traumatic (e.g., sports injury) and atraumatic (e.g., overuse) mechanisms.
• Examination Questions: Crucial questions include: mechanism of injury, swelling, instability, joint sounds, aggravating/alleviating factors, and any other relevant details.
• Bony Anatomy:
  • Tibiafemoral joint: Includes anterior and posterior cruciate ligaments, medial and lateral condyles, collateral ligaments, and menisci.
  • Patellofemoral joint: Involves the patella, femur, and related ligaments and tendons.
  • Tibiofibular joint (proximal): Involves the fibula, tibia, and collateral ligaments.
• Structure and Function:
  • Stability: Provided by quadriceps tendon, patellar ligament, expansions from quadriceps (anterior); medial and lateral collateral ligaments, ITB, pes anserinus insertion (medial/lateral); hamstrings, gastrocnemius, ACL, and PCL (posterior).
  • Joint Capsule: Synovial, large and loose, reinforced by tendons and muscle expansions.
• Muscular Anatomy: Includes vastus lateralis, vastus intermedius, vastus medialis, quadriceps tendon, iliotibial band, lateral retinaculum, semitendinosus, semimembranosus, biceps femoris, gracilis, plantaris, and gastrocnemius.
• Knee Extensor Mechanism:
  • Origin: Rectus femoris from ASIS, vastus muscles from the femoral shaft.
  • Insertion: Quadriceps tendon to superior pole of the patella, patellar tendon to tibial tuberosity.
  • Function: Redirects quadriceps force, creating large compressive stress on patellofemoral joint.
  • Maximum Compression: Occurs when knee is at 90 degrees with foot planted, potential up to 7x body weight in squatting.
• Intercondylar Groove: Important for patellar articulation.
• Clinical Considerations (Osgood-Schlatter's "Disease"):
  • Also known as tibial tuberosity apophysitis.
  • Affects adolescents (8-15 years old), with females often presenting earlier than males.
  • Pain localized over the tibial tuberosity, with possible swelling or a "bump."
• Radiographic Features: Radiographic features of anterior tibial tuberosity development. Example of different ages shown.
• Osteokinematics:
  • Two degrees of freedom: flexion/extension and internal/external rotation.
  • Incongruity and asymmetry of articular surfaces.
  • "Screw-home" mechanism: last 10-15 degrees of knee extension (involuntary).
  • Active tibial rotation possible at 90 degrees of flexion (15-30 degrees).
• Capsular Pattern: Flexion is greater than extension.
• Knee Extension Muscle Testing: Quadriceps strength is significant; avoid overgrading by using a dynamometer or a 1-RepMax leg press.
• Comparison of Four Quadriceps Strength Tests: Single leg sit-to-stand is most predictive of L3 radiculopathy. Tests include single leg sit-stand, step-up, and knee-flexed/extended MMT.
• Knee Flexion Muscle Testing: Medial hamstrings create internal tibial rotation; lateral hamstrings create external tibial rotation.
• Other Considerations: Evaluate hip and foot/ankle complex, functional movements/limitations, and have patients demonstrate their movements.
• Practice! Emphasize good practice.