Knee Ultrasound

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  • Ultrasound of the Knee

    Transverse KneeSagittal Midline Knee

    Sports InjuriesThey may be acute or chronic. Clinical symptoms include:Clinical symptoms include: Pain

    Swelling of the joint

    Joint derangement, with or without locking of the jointJoint derangement, with or without locking of the joint

    MSUS is performed to detect:MSUS is performed to detect: Joint effusion

    Ligament, muscle or tendon tearLigament, muscle or tendon tear

    Plica lesions

    Loose bodies

    Bursitis

    IndicationsMusculoskeletal ultrasound (MSUS) of the extremities is considered a first line examination and is performed in conjunction with conventional radiography.

    The three most common applications for MSUS of the knee are: sport injuries, rheumatologic disorders and periarticular masses.

    Quadriceps tendon

    Prefemoral fat pad

    Suprapatellar recess

    Suprapatellar fat pad

    Patella

    Prepatellar bursa

    Femoral cartilage

    Patellar tendon

    Infrapatellar fat pad

    Deep intrapatellarbursa

    Pretibial bursa

    Skin

    Fibrous capsule

    Posterior cruciateligament

    Anterior cruciateligament

    Lateral patellar retinaculum

    Anterior cruciate ligamentLateral femoral condyle

    Popliteal tendon

    Lateral collateralligament

    Biceps femoris muscle

    Joint space of lateralcompartment of knee

    Plantaris muscle

    Lateral head of gastrocnemius(muscle and tendon)

    Joint capsule

    Medial head of gastrocnemius(muscle and tendon)

    Posterior cruciate ligament

    Pes anserinus(muscle and tendon)

    Semimembranosus -gastrocnemius bursa

    Semimembranosus tendon

    Joint space of medialcompartment of knee

    Medial collateral ligament

    Medial femoral condyle

    Medial patellar retinaculumPatella

  • Interpretation of ultrasound (US) findings in traumatic knees must be correlated with the type of sport activity, the mechanism of injury and in the light of conventional radiography.

    Although other structures of the knee, such as the menisci, articular cartilages and bones, can be partially evaluated by MSUS, they are not accurately demonstrated by MSUS and need further investigation by CT or MRI.

    Rheumatologic DiseasesConventional radiography remains the key examination in the diagnosis of arthritis. However, x-rays are limited to the bone and joint space abnormalities. They do not allow a direct visualization of the soft tissue components of the joints, such as the capsule, synovium, tendons, bursae or ligaments.

    The important roles of MSUS in the diagnosis and management of arthritides are: Detection of joint effusion

    Guidance of joint aspiration or synovial biopsy

    To distinguish intra-articular fluid and synovial fluid in bursa or tendon sheath

    Demonstration of tendon tear

    Assessment of the degree of synovial hypertrophy

    Periarticular or Intra-articular MassesMost masses are found by the patients themselves and are a common reason for consultation. Others are are a common reason for consultation. Others are detected during US examination performed for other detected during US examination performed for other clinical conditions.

    Clinical symptoms related to intra-articular Clinical symptoms related to intra-articular masses are: Knee pain

    Knee effusion

    Locking or internal derangement of the kneeLocking or internal derangement of the knee

    Because clinical examination cannot always detect Because clinical examination cannot always detect the presence of a mass, and often fails to confirm the the presence of a mass, and often fails to confirm the cystic nature of the mass, MSUS is the key examination cystic nature of the mass, MSUS is the key examination and helps in deciding on the next type of investigation and helps in deciding on the next type of investigation when needed.

    US is indicated in the following conditions: To confirm and delineate a mass suspected by

    clinical examination

    To detect intra-articular mass causing internal derangement of the knee

    To confirm the cystic nature of a mass

    To demonstrate complications of surgical procedures in the knee such as hematoma, abscess, seroma or septic arthritis

    To guide aspiration of the joint itself or to tap periarticular fluid collection or cystic mass

    The role of MSUS in the evaluation of periarticular masses is important since these lesions cannot be detected by arthroscopy.

    Other IndicationsUS of the knee can be performed to detect complications (hematoma, abscess, seroma, tumor recurrence) of surgical procedures such as arthrocentesis, arthroscopy, arthrotomy, ACL repair, tumor and cyst resection.

    Scanning TechniqueThe scanning technique should integrate the following considerations: Patient position

    Transducer position

    Position of the joint

    Dynamic maneuver: flexion-extension of the knee and Dynamic maneuver: flexion-extension of the knee and graded compression of articular recessgraded compression of articular recess

    Scanning planes

    Patient positioning anterior approachPatient positioning anterior approach The patient is in a supine positionThe patient is in a supine position

    The knee is flexed at 15 to 20 degreesThe knee is flexed at 15 to 20 degrees

    A pillow is placed under the knee to immobilize the A pillow is placed under the knee to immobilize the extremity in this positionextremity in this position

  • In this position, the following structures are evaluated: Patellar and quadriceps tendons

    Suprapatellar recess

    Patellar retinacula

    Patient positioning posterior approach The patient is in a prone position

    The knee is extended with both feet hanging over the table

    In this position, the following structures are evaluated: Popliteal fossa

    Popliteal vessels and nerves

    Semimembranosus medial gastrocnemius bursa

    Patient positioning lateral approach The patient lies in lateral decubitus position, opposite

    to the knee to be scanned. A pillow should be placed between the knees to stabilize the knee and for patient comfort

    In this position, the following structures are evaluated: Popliteal and conjoint tendons (biceps femoris tendon

    and fibular collateral ligament)

    Iliotibial band

    Fibular collateral ligament (lateral collateral ligament)Fibular collateral ligament (lateral collateral ligament)

    Patient positioning medial approachPatient positioning medial approach The patient is in supine position and partially tilted The patient is in supine position and partially tilted

    towards the affected sidetowards the affected side

    The extremity to be scanned should be held in The extremity to be scanned should be held in external rotation

    The hip and knee are in slight external rotationThe hip and knee are in slight external rotation

    The lateral border of the foot touches the tableThe lateral border of the foot touches the table

    In this position, the following structures are evaluated:In this position, the following structures are evaluated: Medial collateral ligamentMedial collateral ligament

    Pes anserina tendons and bursaPes anserina tendons and bursa

    Probe placement suprapatellar recess Sagittal scanning of the anterior aspect of the knee

    The transducer is placed parallel to the long axis of the quadriceps tendon

    Care must be taken not to excessively compress the recess.

    Probe placement quadriceps tendon The transducer is placed parallel to the long axis of

    the thigh over the suprapatellar region and rotated 90 degrees to obtain transverse scans

    Probe placement patellar tendon The probe is placed in the mid-sagittal plane of the

    anterior aspect of the knee, between the patella and the tibial tubercle

    Probe placement medial collateral ligament The probe is placed at the medial aspect of the joint

    Probe placement lateral collateral ligament/popliteal tendon The probe is placed on the lateral aspect of the knee

    joint, bridging the femoral condyle and the fibular head

    Probe placement iliotibial band The probe is placed at the lateral aspect of the knee

    The entire band can be demonstrated by real-time examination

    It can be followed from its iliac origin to the distal insertion on Gerdy's tubercle of the tibiainsertion on Gerdy's tubercle of the tibia

    Sonographic AnatomySonographic AnatomySuprapatellar recessThe suprapatellar recess is a thin hypoechoic flat sac. It The suprapatellar recess is a thin hypoechoic flat sac. It lies between the suprapatellar and prefemoral fat pads, lies between the suprapatellar and prefemoral fat pads, in the suprapatellar region.in the suprapatellar region.

    Quadriceps tendonThe quadriceps muscles are made of four muscles:The quadriceps muscles are made of four muscles: vastus intermedius

    vastus medialis

    vastus lateralis

    rectus femoris

  • The tendinous extension of the four muscles merge to form the quadriceps.

    The quadriceps tendon is a fascicular and hyperechoic band, running deep to the subcutaneous tissues and inserting on the upper pole of the patella.

    Patellar tendonThe patellar tendon is a fascicular hyperechoic band, bridging the patella and the tibial tubercle. The tendon has slightly larger diameters at the patellar insertion. It appears as an ovoid hyperechoic structure on transverse.

    Medial collateral ligamentIt originates at the medial femoral condyle and inserts on the medial aspect of the proximal tibia. It is made of two layers. Both layers are hyperechoic flat bands. They are separated by a thin hypoechoic band, representing either a fatty tissue or bursa.

    Lateral collateral