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
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.
Prefemoral fat pad
Suprapatellar fat pad
Infrapatellar fat pad
Lateral patellar retinaculum
Anterior cruciate ligamentLateral femoral condyle
Biceps femoris muscle
Joint space of lateralcompartment of knee
Lateral head of gastrocnemius(muscle and tendon)
Medial head of gastrocnemius(muscle and tendon)
Posterior cruciate ligament
Pes anserinus(muscle and tendon)
Semimembranosus -gastrocnemius bursa
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
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
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
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
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
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)
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
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.