Physical examination of the knee
- Anthony Beutler, MD
Anthony Beutler, MD
- Associate Professor of Family Medicine
- Uniformed Services University
- Antoin Alexander, MD
Antoin Alexander, MD
- David Grant Medical Center
- Travis AFB CA Family Medicine Residency Program
- Section Editor
- Karl B Fields, MD
Karl B Fields, MD
- Editor-in-Chief — Primary Care Sports Medicine (Adolescents and Adults)
- Section Editor — Biomechanics, Rehabilitation, and Recovery; Sports-Related Injuries; Symptom Assessment and Physical Examination
- Professor of Family Medicine and Sports Medicine
- University of North Carolina at Chapel Hill
Knee pain and other knee-related complaints are a common reason for visits to primary care clinics and emergency departments. An effective and efficient evaluation of the patient with knee-related complaints depends upon an understanding of the knee's anatomy and function, and the proper performance of an appropriately focused physical examination.
The examination of the knee is reviewed here. A brief review of knee anatomy and biomechanics is also provided. The work-up of patients with knee-related complaints and specific knee injuries and conditions are discussed separately. (See "Approach to the athlete or active adult with knee pain" and "General evaluation of the adult with knee pain".)
Bones and articulations — The knee joint contains four bones—femur, tibia, patella, and fibula—and consists of three compartments—the medial tibiofemoral, lateral tibiofemoral, and patellofemoral—all sharing a common synovial cavity (picture 1 and picture 2 and figure 1 and picture 3 and picture 4 and picture 5). The knee has three articulations: medial and lateral tibiofemoral and patellofemoral. The tibiofemoral articulations connect the distal femur, which broadens to form the medial and lateral femoral condyles, and the tibia. The tibia is relatively flat, but the sloped menisci permit a tight articulation with the convex femoral condyles. The femoral condyles are separated by an intercondylar fossa, also called the femoral groove or femoral trochlea.
The patella is a sesamoid bone embedded in the quadriceps tendon that articulates with the trochlear groove of the femur (picture 6 and figure 2). Its function is to increase the mechanical advantage of the quadriceps. The fibular head lies within the capsule of the knee but is not normally involved as a weight-bearing surface. The joint lines are formed by the femoral condyles and the tibial plateaus.
Structures providing support and stability — Several soft tissues contribute to knee stability and provide cushioning within the joint. The parts of the tibia and femur contained within the knee joint are lined with shock absorbing hyaline cartilage. Disc-shaped lateral and medial menisci provide additional shock absorption and distribute forces across the joint. The anterior and posterior cruciate ligaments provide stability with anterior and posterior movements and with flexion and extension; the medial and lateral collateral ligaments provide support in their respective planes. Other structures that contribute to knee stability include the iliotibial band and parts of the posterolateral corner.
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- Bones and articulations
- Structures providing support and stability
- Structures involved in knee extension
- Popliteal fossa and structures involved in knee flexion
- Bursa and cystic structures
- Neurovascular structures
- TIPS FOR A PRODUCTIVE EXAMINATION
- Observe gait
- Swelling and ecchymosis
- Skin changes
- General approach
- Joint line palpation
- - Lateral joint line
- - Medial joint line
- Anterior knee off the joint line
- Posterior knee
- Skin temperature
- DETECTION OF AN EFFUSION
- RANGE OF MOTION AND MUSCLE FLEXIBILITY
- NEUROVASCULAR ASSESSMENT
- MOTOR FUNCTION AND STRENGTH
- Quadriceps strength
- Hamstring strength
- Functional strength tests
- ASSESSING JOINT STABILITY
- Valgus stress test for medial instability
- Varus stress test for lateral instability
- Tests for ACL injury and anterior stability
- Tests for PCL injury and posterior stability
- - Posterior drawer test
- - Posterior sag sign
- - Quadriceps active test
- - Dial test
- SPECIAL TESTS FOR SPECIFIC CONDITIONS
- A word of caution
- Tests for patellofemoral pain syndrome
- Tests for meniscal tear
- Tests for iliotibial band syndrome
- SUMMARY AND RECOMMENDATIONS