Extensor Carpi Ulnaris (ECU) tendinosis with interstitial tear

Extensor carpi ulnaris tendinosis is one of the common causes of ulnar sided wrist pain. Extensor carpi ulnaris passes through a fibro-osseous tunnel (the sixth extensor compartment), lying within a bony groove on the dorsal surface of ulna. ECU is maintained in this groove by the extensor retinaculum and the ECU subsheath. The ECU subsheath is not attached to the tendon.

The ECU originates from two heads, one from lateral epicondyle and other from the posterior middle third of ulna and distally it inserts into the posterior aspect of the base of fifth metacarpal.  

Racquet Sports and golf athletes are at an increased risk of ECU tendon pathology. In non-athletes rheumatoid arthritis is also to be excluded. The pathologies which can affect the ECU tendon includes tenosynovitis, tendinosis, tendon instability and rupture.

The PDFS axial and coronal image above shows mild thickening and intermediate signal intensity of the ECU tendon favoring tendinosis, with thickening and hyperintense signal intensity of the tendon sheath with associated mild soft tissue edema (suggesting tenosynovitis).

Serial axial sections of the wrist (clockwise) shows thickened ECU tendon with irregular shaped hyperintense intrinsic linear signal intensity favoring and interstitial tear.

No subluxation or dislocation of the ECU tendon is noted from the ulnar groove. The ECU subsheath and the extensor retinaculum appears intact. The orange thick arrow corresponds to the retinaculum and the thin green narrow corresponds to the ECU subsheath.

The above T2 axial image of the wrist is also showing the intact ECU subsheath (green narrow).

References: 

1. https://radiopaedia.org/articles/extensor-carpi-ulnaris-tendinopathy
2. https://radsource.us/extensor-carpi-ulnaris-subsheath-injury/

Patellar Dislocation and Relocation (PDR)

20Y old male presented with history of fall and direct injury to anterior knee.

The above axial PDFS images demonstrate the torn medial patello-femoral ligament (MPFL, blue arrow) and the medial patellar retinaculum (orange arrow) more distally. Marrow edema is noted in the medial portion of the patella (green arrow). Lateral patellar tilt, mild to moderate joint effusion and shallow trochlear sulcus angle (145°) ( suggesting trochlear dysplasia) were also noted. The lateral trochlear inclination angle measured approximately 10°.

The two axial and last coronal PDFS images shows the contusion in the lateral femoral condyle, caused due to the impaction by the dislocated patella.

Here the first image is showing the PDFS coronal image in the anterior aspect of the knee, with the arrow pointing to edema in the inferomedial anterior aspect of patella with small a avulsion fragment. Axial and coronal CT bone window images shows multiple small chip/avulsion fractures of the medial patella. In the CT sections of patella appear slightly laterally subluxed. (Note: The small fragment like appearance of the femoral condyles in CT axial section is actually due to the physeal plate, and not fractures).

The above PDFS sagittal image shows injury to the Hoffa's fat pad represented by the yellow arrow heads. The image on the right (T2 sagittal) shows increased Insall-Salvati Index, measuring 1.55, suggestive of Patella Alta. 

The risk factors of patellar dislocation include shallow patellar depth, shallow trochlear sulcus, dysplasia of the femoral condyle or patella, lateral position of the tibial tuberosity, patella alta, patellar dysplasia (nail patella syndrome) , ligamentous laxity (Marfan syndrome, Ehlers Danlos, Down's syndrome and polio) and tight lateral retinaculum.

The most common finding in the patellar dislocation is hemarthrosis or lipohemarthrosis. 

The contusion in the lateral femoral condyle which may be seen up to 80-100% of patients and is considered most specific MR imaging finding of a patellar dislocation. The contusion of the lateral femoral condyle seen in the patellar dislocation/relocation is located more anteriorly, laterally and superiorly when compared to the ACL injury contusion pattern.

Patellar contusion is seen in approximately 40% of the patients and is located in the medial and inferior aspect of the patella, in relation to the attachment of the medial retinacular complex.

The injury pattern characteristic of 'patellar dislocation/relocation' is the so called 'kissing contusions' because of the patella compressing on the lateral femoral condyle during dislocation.

Reference:

Thomas Lee Pope, MR imaging of patellar dislocation and relocation, Seminars in Ultrasound, CT and MRI, Volume 22, Issue 4, 2001,Pages 371-382, ISSN 0887-2171,
https://doi.org/10.1016/S0887-2171(01)90027-7.

Special Thanks to Prasad George, Senior MRI Technologist. 😆

Septic arthritis of hip joint

 Young male patient with fever of ~5-6 weeks duration, right hip pain.

STIR Coronal : Green arrow - joint effusion, Orange arrow: asymmetric red marrow / marrow edema.
(See last MRI image also)

STIR Axial image, Grade 3 joint effusion

STIR Axial image, marked.

Thickening and enhancement of the joint capsule / synovial layers.

Ultrasound: Echogenic fluid with debris within the anterior synovial recess. Anterior peri-articular muscle edema+. Probe tenderness+.

Eventhough the T1 hypointense signals in the intertrochanteric region (left) can be explained by the presence of residual red marrow in this 20yr old patient, the signal intensity is markedly reduced on right side, suspicious of marrow edema.

Ring shaped lateral meniscus

Ring shaped lateral meniscus is a very rare anatomical variant which can easily mimic and make it difficult to distinguish from a bucket handle tear. Unlike the normal C-shape, this variant forms a complete ring.

Usually the lateral portion appears as in normal cases, with angular margins or sometimes can appear deficient anteriorly. The additional medial component appear like displaced torn fragment and easily gets mistaken for a bucket handle tear (where the body of meniscus will be truncated c.f. ring meniscus).

In differentiation from central perforation of a discoid lateral meniscus, the inner margins in central perforation will be irregular with degenerative changes. Associated osteophytes and chondral lesions may also be seen unlike a case of ring shaped lateral meniscus.

Transient Synovitis of Hip Joint

Transient Synovitis (Coxitis fugax) is the most common cause of acute hip pain in children aged 3 to 10 years. It is a self-limiting acute inflammatory condition which is managed symptomatically. However it needs to be differentiated from Septic Arthritis, which will require antibiotics and surgical drainage.¹

Over 90% of hip joint effusions can be attributed to transient synovitis. ²
It has a male gender predilection and more frequently affects the right hip joint.

Etiology of transient synovitis remains unknown. Various theories include response to infection (URTIs), trauma, allergen / antigen etc. Clinical, laboratory and radiological findings help in differentiating Transient Synovitis from Septic Arthritis. The latter is usually associated with fever, elevated ESR & CRP.

X-Ray may reveal mild joint space widening due to effusion. Ultrasound is often the initial modality as it can reliably assess presence of joint effusion in the anterior recess.

MRI findings of Transient Synovitis include:
1. Joint effusion.
2. Synovial thickening & enhancement.
3. Adjacent soft tissue edema, with characteristic absent bone marrow edema.
4. Contralateral effusion (lesser volume usually).

Below MR images are of a 10yr old girl child with limping showing features of transient synovitis in right hip joint. No bone marrow edema or contra-lateral effusion is seen in this child. Grade 3 joint effusion is present in right hip joint.

Very rarely Transient Synovitis can cause osteonecrosis. But most often with analgesics and other symptomatic treatment, it resolves gradually, without any known long term sequelae. Eventhough it is most commonly seen in children, tranisent synovitis can also develop in adults.

Hip joint effusion is graded according to Mitchell Classification. 0 : None, 1 Minimal, 2 - Enough to surround the femoral neck and 3 distension of joint recesses.

References:

1. MR imaging of transient synovitis: Differentiation from septic arthritis. Pediatric Radiology, 2006.
2. Radiopedia.

Nasu Hakola disease

• Rare hereditary Autosomal Recessive disorder.
• Also known as Polycystic Lipomembranous Osteopathy with Sclerosing Leukoencephalopathy (PLOSL). 
• Progressive presenile dementia, with associated recurrent bone fractures, due to cystic lesion of long bones. 
• Progresses in  4 stages: Latent, Osseous, Early neurologic and late neurologic. The disease may not be recognized until the neurologic symptoms start in the third or fourth decade, characterized mainly by frontal lobe symptoms of loss of concentration, loss of social inhibition, loss of judgement etc.
• Radiologically white matter hyperintensities of brain, neuroparenchymal atrophy, basal ganglia calcifications, especially putaminal etc are noted. Caudate head atrophy with widening of frontal horns as in Huntingtons disease may be seen, with increased intercaudate distance to inner table width ratio.
• No treatment is available at present and death usually occurs by 5th decade.

How strong is your 'Shoulder Anatomy' ?

Click on this image for answer !!!

MRI assessment of Suprapinatus atrophy and fatty replacement

THOMAZEAU's OCCUPATION RATIO (SUPRASPINATUS)
 Muscle atrophy of the supraspintatus is assessed by method suggested by Thomazeau et al, by which the 'occupation ratio' is calculated. Occupation ratio has been defined as the ratio between the cross section of the muscle belly and that of its fossa on the Y-view. The Y-view is the oblique sagittal (T1 WI) plane that crosses the scapula through the medial border of the coracoid process.

Hoffa's Fat Pad Impingement Syndrome

    Patient : Young female with bilateral occasional knee pain, right > left.

The sagittal PD-FS images show hyperintense signals in the Hoffa's Fat pad superiorly, on the lateral aspect only. The medial fat pad shows normal signal intensity.

On AXIAL PD-FS images these hyperintensities are noted, between the Patellar Tendon (PT) and the Lateral Femoral Condyle (LFC) - consistent with the Patellar Tendon - Lateral Femoral Condyle - Friction Syndrome ( PT-LFC-FS) which is synonymous with Hoffa's Fat Pad Impingement Syndrome.

Lumbosacral transitional vertebrae

SYNONYMS : Lumbosacral transitional segment, lumbarization, sacralization, lumbosacral transanomaly, borderline vertebra.

A lumbar segment with enlarged transverse elements and an upper sacral segment with  lumbar-type posterior elements are the two most common presentations.
The relationship of LSTV to back and leg pain has long been a subject of debate.
The association of back pain with antalgic scoliosis was first described by Bertolotti in 1917 
(sacralization douleureuse, Bertolotti’s syndrome).

Radiological Findings: 

LSTV is characterized by enlargement of the transverse process(es). Frontal and lateral views should be performed and preferably supplemented with an angulated view of the lumbosacral junction (Ferguson-Hibb view).

Note: L3 has the longest transverse process and L4 has a pointed TP. 

Castellvi et al described a radiographic classification system identifying 4 types of LSTVs on the basis of morphologic characteristics.

Type I includes unilateral (Ia) or bilateral (Ib) dysplastic transverse processes, measuring at least 19 mm in width (craniocaudad dimension).Here the transverse process is expanded toward its tip as a spatulated bony process that is < 19 mm with no obvious connection to the sacral ala. This anomaly has a dubious role in back pain syndromes.

Type II exhibits incomplete unilateral (IIa) or bilateral (IIb) lumbarization/sacralization with an enlarged transverse process that has a diarthrodial joint between itself and the sacrum. The joint is usually referred to as a pseudo-articulation and is marked radiologically by corticated opposing bony surfaces with a 1- to 2-mm joint space. The vertebral body is often small and wedged laterally with narrowing on the side of attempted union, often precipitating a scoliosis. On the lateral view, a transitional vertebral body will be wedged posteriorly and the inferior endplate length will typically be less than the superior endplate length by a ratio of 1.37 or less (squaring sign). The intervening disc and facet joints are usually hypoplastic.

Type III LSTV describes unilateral (IIIa) or bilateral (IIIb) lumbarization/sacralization with complete osseous fusion of the transverse process(es) to the sacrum, with no visible joint.

A : Ordinary AP View B: Cranially Angulated (tilt-up) X Ray with central beam parallel to L5-S1 Disc shows a right sided type III LSTV.

Type IV involves a unilateral type II (pseudo-joint type) transition with a type III (osseous fusion) on the contralateral side.


Ref : Lumbosacral Transitional Vertebrae @ AJNR
        ESR 3rd Edition.

Fibrodysplasia Ossificans Progressiva

1. Bilateral Hallux Valgus - with malformed first metatarsal and phalanges.

2. Medial cortical thickening with formation of Pseudo-exostosis ( Calcification of Gracilis / Semitendinosus tendons).

3. Shortened first metacarpals

4. Usually the hetrotopic ossification begins in the soft tissues of neck, even after trivial trauma.

5. FNAC is contraindicated as it can result in permanent deforming ossification.

6. F.O.P is an AD disease with complete penetrance,, but with variable expressivity.

7. Can be diagnosed by the HALLUX VALGUS. Genetic testing is available.

8. Small vertebral bodies, enlarged pedicles, small spinal canal may be seen.

9. Starts by 2-5yrs, Death by 3rd decade by recurrent pulmonary infections due to prevention of expansion of thoracic cage (Impairing Respiration).

Osteoscerotic Lesions : Mnemonic

'Regular sex makes occasional perversions much more pleasurable and fantastic.'




Mnemonic for osteosclerosis


Renal osteodystrophy
Sickle cell disease
Myelofibrosis
Osteopetrosis
Pyknodysostosis
Metastases
Mastocytosis
Paget disease
Athletes
Fluorosis

Bullet shape in Radiology

1. Bullet shaped Posterior Urethra – in PUV MCU.

2. Bullet shaped Thoraco-lumbar vertebrae in Lateral XR spine in Achondroplasia.

3. Bullet shaped metacarpals - MPS

4. Tumbling bullet sign : is seen in bullet within a post-traumatic bone cyst.

5. Bullet shaped third ventricle  : Joubert Syndrome.

Spotter 6 ?

Kienböck’s Disease

General Considerations


Osteonecrosis of the carpal lunate.
Clinical Features
Males 9:1; 20-40 years of age.
History of acute or chronic trauma.
Worsening pain and disability.

Pathologic Features


Avascular necrosis; resorption, deposition, fragmentation, collapse.
Cause obscure, possibly owing to trauma, vascular vulnerability, and a short ulna.

Radiologic Features
Increased density, lucent areas, articular collapse, decreased size of the lunate.