knee ultrasound

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Ultrasound of the Knee Transverse Knee Sagittal Midline Knee Sports Injuries They may be acute or chronic. Clinical symptoms include: ude: Pain Swelling of the joint Joint derangement, with h or without locking of the joint MSUS is performed to o detect: Joint effusion Ligament, muscle or ten ndon tear Plica lesions Loose bodies Bursitis Indications Musculoskeletal 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 intrapatellar bursa Pretibial bursa Skin Fibrous capsule Posterior cruciate ligament Anterior cruciate ligament Lateral patellar retinaculum Anterior cruciate ligament Lateral femoral condyle Popliteal tendon Lateral collateral ligament Biceps femoris muscle Joint space of lateral compartment 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 medial compartment of knee Medial collateral ligament Medial femoral condyle Medial patellar retinaculum Patella

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Page 1: Knee Ultrasound

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

Page 2: Knee Ultrasound

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

Page 3: Knee Ultrasound

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

Page 4: Knee Ultrasound

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 ligament/popliteal tendonThe lateral collateral ligament originates at the femoral condyle and inserts distally on the head of the fibula. Before its distal insertion, it merges with the biceps femoris tendon to form the conjoint tendon.

The popliteal tendon courses through the posterior horn of the lateral meniscus and inserts in a notch of the lateral femoral condyle, deep to the proximal portion of the lateral collateral ligament. the lateral collateral ligament.

Iliotibial bandThis band represents the aponeurosis of the tensor This band represents the aponeurosis of the tensor fascia lata which arises from the iliac crest and the fascia lata which arises from the iliac crest and the anterior superior spine of the ilium, and inserts distally anterior superior spine of the ilium, and inserts distally on the anterior lateral aspect of the proximal tibia on the anterior lateral aspect of the proximal tibia at Gerdy’s tubercle. It lies immediately under the at Gerdy’s tubercle. It lies immediately under the subcutaneous tissue, and is therefore easy to detect, subcutaneous tissue, and is therefore easy to detect, appearing as a thin fascicular hyperechoic band.appearing as a thin fascicular hyperechoic band.

Lateral patella retinaculumLateral patella retinaculumThe patellar retinaculum appears as a hyperechoic The patellar retinaculum appears as a hyperechoic band originating from the iliotibial band and the vastus band originating from the iliotibial band and the vastus lateralis muscle. It runs obliquely and transversely and lateralis muscle. It runs obliquely and transversely and inserts on the patella and the patellar tendon, and is inserts on the patella and the patellar tendon, and is composed of two layers.composed of two layers.

Medial patella retinaculumAlso composed of two layers, it originates from the sartorius and vastus medialis muscles and runs obliquely and transversely, and inserts on the medial aspect of the patella.

Posterior cruciate ligament (PCL)Normal PCL appears as a hypoechoic beak-like structure. The low echogenicity is most likely related to anisotropic artifact. The distal portion of the PCL and its bony insertion can be easily demonstrated placing the transducer at midline of the popliteal fossa along the axis of the tibia and then rotating the transducer.

Anterior cruciate ligament (ACL) A normal ACL appears as a hyperechoic band. The anterior approach, with the knee flexed more than 90 degrees is used. The transducer is placed at the medial infra-patellar area along the axis of the tibia. The transducer is then rotated 30 degrees counterclockwise for the right knee and 30 degrees clockwise for the left knee.

BursaeMedial semimembranosus/gastrocnemius bursa: Its neck lies between these two tendons, at the medial aspect of the popliteal fossa.

Suprapatellar bursa or recess: It lies deep to the quadriceps tendon and extends about 6 cm above the patella. It represents the upper extent of the articular cavity.

Prepatellar bursa: It is located in the subcutaneous tissue, superficial to the anterior aspect of the patella.

Superficial infrapatellar bursa: It is located between the Superficial infrapatellar bursa: It is located between the tibial tubercle and the skin.tibial tubercle and the skin.

Deep infrapatellar bursa: It is located between the distal Deep infrapatellar bursa: It is located between the distal patellar tendon and the tibial tubercle.patellar tendon and the tibial tubercle.

Pes anserina bursa: It is located underneath the Pes anserina bursa: It is located underneath the semitendinosus, gracilis, and sartorious tendons, which semitendinosus, gracilis, and sartorious tendons, which together form the pes anserina tendon. It inserts at the together form the pes anserina tendon. It inserts at the anteromedial aspect of the proximal tibia.anteromedial aspect of the proximal tibia.

Iliotibial bursa: It is located between the distal iliotibial Iliotibial bursa: It is located between the distal iliotibial band and the lateral femoral condyle.band and the lateral femoral condyle.

Fibular collateral ligament/biceps femoris bursa: It is Fibular collateral ligament/biceps femoris bursa: It is located between the anterior arm of the long head of located between the anterior arm of the long head of the biceps femoris and the fibular collateral ligament.the biceps femoris and the fibular collateral ligament.

Page 5: Knee Ultrasound

This longitudinal image demonstrates the normal appearance of the proximal patellar tendon.

On this longitudinal image, the suprapatellar bursa is seen between the two fat pads. Also the quadriceps tendon is seen inserting on the superior border of the patella.

This longitudinal image shows the medial collateral ligament (MCL) at the level of the medial meniscus.

Transverse scan of the medial retinaculum originating from the patella and extending medially.

Transverse view of the medial popliteal fossa demonstrating the semimembranosus/gastrocnemius bursa (B). MG: medial gastrocnemius muscle, SM: semimembranosus tendon.

Transverse view of the medial popliteal fossa demonstrates Transverse view of the medial popliteal fossa demonstrates a large baker’s cyst which is an abnormal dilation of the a large baker’s cyst which is an abnormal dilation of the semimembranosus/gastrocnemius bursa.semimembranosus/gastrocnemius bursa.

Page 6: Knee Ultrasound

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www.medical.philips.com/ultrasound

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© Koninklijke Philips Electronics N.V. 2003. All rights are reserved. Reproduction in whole or in part is prohibited without prior written consent of the copyright holder.

Philips Medical Systems Nederland B.V. reserves the right to make changes in specifications or to discontinue any product, at any time without prior notice or obligation, and will not be liable for any consequences resulting from the use of this publication.

Printed in USA G64215 6-03

REFERENCES1. van Holsbeeck M, Introcaso JH. Musculoskeletal Ultrasound. Mosby-Year Book, St. Louis, 1991.

2. Chhem R K, Cardinal E. Musculoskeletal Ultrasound. Guidelines and Gamuts, New York, J Wiley & Sons Publishers, 1999.

3. Starok M, Lenchik L, Trudell D, Resnick D: Normal Patellar Retinaculum. MR and Sonographic Imaging with Cadaveric Correlation. AJR 168 (6): 1493-1499, 1997.

4. Richardson ML, Selby B, Montana MA, Mack LA. Ultrasonography of the Knee. Radiologic Clinics of North America 26 (1): 63-75, 1988.

5. Suzuki S, Kasahara K, Futami T et al. Ultrasound diagnosis of pathology of the anterior and posterior cruciate ligaments of the knee joints. Archives Orthopedic & Trauma Surgery 110 (4): 200-203, 1997.

CLINICAL SOURCESRethy K Chhem, MD, PhDToronto, Ontario, Canada

Jag Dhanju, RT (R) RDMSToronto, Ontario, Canada

This longitudinal image displays the lateral collateral ligament (LCL) at the level of the lateral meniscus.

This longitudinal scan shows the insertion of the iliotibial band to Gerdy’s tubercle of the tibia.

This longitudinal image shows acute fusiform patellar tendinitis.

Acutely swollen medial collateral ligament (MCL) is seen Acutely swollen medial collateral ligament (MCL) is seen above the level of the medial meniscus.above the level of the medial meniscus.