STRESS FRACTURE OF FIBULA

PDFS-SAG

T1 SAGITTAL

T1 AXIAL

PDFS-AXIAL

A 17 year old football player presented with pain in left distal leg and ankle.
MRI shows an incomplete fracture line involving the distal fibular shaft along the lateral aspect with sparing of medial part and is associated with marrow oedema. There is periosteal marrow oedema around it, more on the anterolateral aspect.

STRESS FRACTURES OF FIBULA:

• They are usually secondary to repetitive overuse or stress as in runners, hikers and players.
• May be seen along with stress fractures of tibia or medial tibial stress syndrome or on their own.
• They account for approximately 10% of stress fractures
• They usually involve the distal one-third of fibula
• Plain radiographs may be normal initially. 
• They are best picked on MRI. 
• Bone scintigraphy is also useful.
• On MRI, typical features are those of periosteal thickening and periostitis along with oedema around the fibular cortex.
• An incomplete fracture line may be seen within the cortex.

 REFERENCES:

• Berger F, Jonge M D, Smithius R et al: Stress fractures. Radiology Assistant:2007( e-reference)
• Stoller D W, Ferkel R D, Li A E et al: The Ankle and Foot. Magnetic Resonance Imaging in Orthopaedics and Sports Medicine:Third Edition.Lippincott Williams & Wilkins:1003, 2007.

PIGMENTED VILLONODULAR SYNOVITIS

SAGITTAL PDFS IMAGE SHOWING LARGE SYNOVIAL EFFUSION WITH SYNOVIAL THICKENING

SAGITTAL PDFS IMAGE SHOWING MULTIPLE NODULAR MASSES IN THE JOINT SPACE POSTERIORLY SHOWING HYPOINTENSE FOCI AND HYPOINTENSE RIM(  HEMOSIDERIN)

SAGITTAL PDFS IMAGE SHOWING SIMILAR NODULAR MASSES IN HOFFA'S FAT PAD.

STIR CORONAL IMAGE SHOWING HYPOINTENSE NODULAR SYNOVIAL THICKENING ON THE LEFT SIDE

AXIAL GRE IMAGE SHOWING "BLOOMING" OF NODULES/NODULAR SYNOVIAL THICKENING

AXIAL GRE IMAGE SHOWING BLOOMING OF NODULES

AXIAL GRE IMAGE SHOWING SIGNIFICANT BLOOMING OF SYNOVIAL BASED NODULES SUGGESTIVE OF HEMOSIDERIN CONTENT

SAGITTAL T1 IMAGE SHOWING ALMOST ISOINTENSE NODULES

49 year old patient presents with joint swelling and pain.
MRI reveals large synovial effusion with synovial thickening. There are multiple nodules within the joint which show hypointense areas on fluid sensitive sequences and bloom significantly on GRE suggestive of hemosiderin content.

PIGMENTED VILLONODULAR SYNOVITIS: 

• Benign, locally aggressive lesion
• Characterised by an abnormal synovial lining which is prone to hemorrhage with minor trauma resulting in repeated hemorrhagic effusions and iron deposition in the synovium and nodules
• There may be bony erosions and subchondral cysts with nodular proliferaition of synovium
• Patient presents with an insidious onset of painful joint swelling. Sometimes, torsion of nodules may cause sudden sharp rise in pain.
• Usually mono-articular
• There is a wide age range of presentation but commonest being 30-40 years.
• If untreated, repeated bleeding and synovial proliferation with erosions may lead to joint destruction. 
• GRE is most important sequence in MRI for its diagnosis as it elicits characteristic "blooming" of lesions.

DIFFERENTIALS:

INTRA-ARTICULAR NODULAR SYNOVITIS

•  May be completely identical to PVNS on MRI
• Generally show less effusion  and less hemosiderin than PVNS

 SYNOVIAL CHONDROMATOSIS

• generally loose bodies are seen on radiographs
• Sometimes conglomerate los signal masses on MRI in the synovium may be confused with PVNS but do not bloom on GRE

HEMOPHILIAC ATHROPATHY:

• Effusion with synovial proliferation
• Blooms on GRE
• However, morphologyis different with overgrown epiphyses/ metaphyses
• Also is often familial

REFERENCE:
Manaster BJ:Pigmented Villonodular synovitis( PVNS). Diagnostic Imaging Musculoskeletal: Non-Traumatic Disease: First Edition.Amirsys:I-134,2010.

Trevor Fairbank disease/ Dysplasia Epiphysealis Hemimelica

Figure 1

Figure 2

Figure 3

Figure 4

Figure5

Figures 1 to 5 ( T1, STIR coronal images) show cartilaginous intra-articular masses or overgrowth along with ossification arising from the medial aspect of left distal femoral, proximal tibial and distal tibial epiphyses with resultant deformity of the knee and ankle joints and limb length discrepancy. This fits into the classic form of Trevor Fairbank disease/ Dysplasia sepiphysealis hemilelica.

BACKGROUND AND HISTORY: Dysplasia epiphysealis hemimelica is a rare development disorder of epiphyses in children.
Mouchet and Berlot described it in 1926 in tarsal bones calling it "tarsomegalie".
In 1950, Treor described 10 cases naming it as "tarsoepiphyseal aclasis"
In 1956, Fairbank described 14 cases and coined the term "dysplasia epiphysealis hemimelica".

The disease is thought to be an osteochondroma of the joint.
It is mostly described in epiphyses and also occurs in seasmoid bones like the patella.
It is most commonly described in lower limb, mainly involving the knee and ankle.
It is hemimelic affecting the medial or lateral aspect of ossification centre, being twice as common in medial aspect as compared to lateral aspect.

EPIDEMIOLOGY:
 Prevalence  is 1 in 1 million
It is three times more common in boys
Non-hereditary  of unknown aetiology
First presents between 2-14 years of age

PRESENTATION:
Child usually presents with painless asymmetric firm swelling affecting one side of a lower limb joint.
There may be limb wasting, varus/ valgus deformity, anular deformities, joint locking, limb lengthening discrepancies etc.
Upper limb involvement and bilateral involvement have been described in literature but are extremely rare.

TYPES:
 Three types:Localized, classic and generalized

Localized variety: Single bone is affected, usually hindfoot or ankle
Classic variety:Affects more than 1 area in a single lower limb, usually knee and ankle. It accounts for more than two-thirds of the cases
Generalized form: Most severe form. Affects the whole lower limb from pelvis to foot.

Figure 1

IMAGING

Radiography: X-rays reveal mass with early focal ossification in medial or lateral side of the epiphysis (may be one or more). The lesions enlarge and ossify with bone maturation and may unite with the underlying bone. There may be premature closure of epiphysis with resultant limb length discrepancies.
There may be early secondary osteoarthritis .
There may be secondary involvement of metaphysis.
CT: shows anatomic relationship between mass and bone like cortical/ medullary bone continuity

MRI: shows anatomic relations better and also helps in identifying the tumour.
It shows signal intensity of lesion as  well as continuity with the primary site.

TREATMENT:
Observation or surgical
Surgery is only indicated if patient presents with severe pain and/ or deformity  or if there is locking of the joint.

RECURRENCE: is high after surgery

REFERENCES:
Araujo CR et al:Dysplasia Epiphysealis Hemimelica of Patella.Radiographics. 26:581-6, 2006
Bakarman KA: Dysplasia Epiphysealis Hemimelica.Medscape Radiology

MILWAUKEE SHOULDER

T2 GRE-AXIAL

T2FS-AXIAL PLANE

PDFS-CORONAL PLANE

STIR-SAG PLANE

H

T1-SAG PLANE

 60 year old female with shoulder pain and decreases range of motion: Above images show large globular foci of hypointense signal on all sequences in the infraspinatous tendon/ associated bursa  s/o calcification due to Hydroxyapatite deposition disease. There is fluid in adjacent bursa / oedema in adjacent soft tissues.

TALOCALCANEAL COALITION

STIR coronal image

STIR coronal image

PDFS-sagittal image

T1-sagittal image

T1-sagittal image

Coronal and sagittal T1, STIR and PDFS sequences in a 30 year old female showing talocalcaneal coaltion.
There is continuity of marrow fat from the talus through the sustentaculum tali.
Secondary signs of talocalcaneal coalition are seen with talar beaking ( on last image).

This 30 year old female presented with rearfoot pain localized to the medial part of the foot along with flat foot.


Talocalcaneal coalition respresents 37 % cases of tarsal coalition with calcaneo-navicular coalition being the most comon type( 53 %).
Talocalcaneal coalition can occur through any of the 3 facets but is most common in the middle facet through the sustentacumum tali. These are best evaluated  on coronal images.
In fibrous coalition, there may be subchondral marrow oedema.

Secondary signs of a talocalcaneal coalition include:
Talar beaking adjacent to talonavicular articulation- also seen on lateral x-rays
Degenerative dorsal changes in calcaneocuboid joint

REFERENCES:

• Stoller DW, Ferkel RD: The Ankle and Foot. Magnetic Resonance Imaging in Orthopaedics and Sports Medicine: Volume I: Third Edition. Lippincott Williams & Wilkins:1009-1013, 2007.
• Radiopaedia.org

SIMPLE BONE CYST

T1 and STIR coronal and sagittal MR images in a 4 year old child showing a fairly well demarcated expansile septate cystic lesion in the proximal metaphyseal region of right humerus. It displays mild heterogeneity but is largely homogenous.

SIMPLE BONE CYST: 
-90% occur in long bones, most common in proximal humerus
-Metaphyseal expansile cystic lesion
-May contain "fallen fragment" which is  a fractured fragment of bone which moves in dependent part with change in patient position. It is usually seen on x-rays and CT.
-May show fluid-fluid level on CT and MRI
-"Rising bubble sign" : Bubble of gas in non-dependent part of lytic lesion suggestes pathologic fracture. It may be seen on CT and MRI.
-FDG active, may hence mimic metastasis on PET-CT

REFERENCE:
Manaster BJ, Roberts CC, Petersilge CA, Moore S, Hanrahan CJ, Crim J.Diagnostic Imaging Musculoskeletal: Non-traumatic disease. Amirsys.2-206, 2010

CVJ CARIES

Fig 1-STIR coronal

Fig 2 -T2 sag

Fig 3- T1 sag

Fig 4- T2 axial

Fig 5- CT ( axial plane)

A 56 year old man presented with 3 months history of increasing cervical pain and stiffness. MR and CT showed bony destruction involving atlas, axis and occipital condyles with large pre/ paravertebral and epidural collections causing significant thecal sac effacement. The cord was indented but showed no signal change.

Intracapsular Osteoid Osteoma

T1 coronal

T2 coronal

STIR-coronal

T1FS( contrast)-coronal

PDFS-axial

T1FS(contrast)-axial

STIR-coronal

A 27 year old female patient presented with long standing severe left hip pain. Contrast enhanced MRI showed cortical thickening and a small round well-defined area of signal alteration in anteromedial cortex of neck of left femur (isointense signal to skeletal muscle on T1, target apearance on T2/ STIR/PDFS) and  intense peripheral enhancement after contrast suggestive of osteoid osteoma. There is mild effusion in left hip joint.


A non-contrast MR scan performed 6 monthes earlier ( not shown here) showed significant left hip joint effusion and synovial thickening along with a poorly marginated large area of marrow oedema in the left femoral neck. A diagnosis of infective arthritis was made ( the intracapsular osteoid osteoma was overlooked). The patient was treated with antibiotics but showed persistence of pain with mild improvement.

INTRODUCTION: 
 Osteoid osteomas are benign bone forming tumours.

DEMOGRAPHICS:

• 10-25 years of age
• M>F( 3:1)
• Relatively common being 4-10%of primary bone tumours( excluding myeloma)

CLINICAL PRESENTATION:

• Severe pain which is worse at night and is relieved by salicylates or nonsteroidal anti-inflammatory drugs in 80% patients. It is intially intermittent and becomes unremitting later.
• Intracapsular lesions present with signs of synovitis, joint pain and reduced range of movement
• Premature osteoarthritis can occur with chronic intracapsular lesions ( in 50% cases)
• Intracapsular lesions can also cause growth abnormalities
• Muscle atrophy and neurologic signs are rare

IMAGING:
LOCATION:

• Cortical diaphyseal: commonest (65-70%) with femur being the commonest site
• Intramedullary : Rare and involves carpal and tarsal bones
• Intracapsular: usually in femoral neck, calcar. Has also been reported in elbow, foot, wrist, knee and facet joints
• Subperiosteal: Usually intracapsular( common in hip and talus)
• Spine:10% and involves posterior elements( Lumbar commonest site)
• Multifocal synchronous lesions: rare

X-RAY FINDINGS


Cortical diaphyseal:

• Oval lytic lesion with surrounding cortical sclerosis which may obscure lytic nidus
• The nidus may have central calcification which is seen as a raiopaque point called the Bell

Intracapsular( intra-articular):

• Oval lytic lesion in cortex with or without surrounding sclerosis.
• Sclerotic bone may be at distant site from the lesion
• Joint effusion

CT FINDINGS:

• Accurate in specifying location: cortical vs subperiosteal/ intramedullary
• Scerotic reaction seen
• Lytic nidus better seen
• Assciated pathologic fracture may be seen
• Helpful for guidance of percutaneous RF ablation

MR FINDINGS:
Nidus:

• Low to intermediate signal on T1
• Variable intensity on T2 depending on mineralization.
• Intense and dynamic enhancement( maximum in arterial phase)
• With increased spatial resolution, a partially mineralized nidus has a target appearance with mineralized portion appearing hypointense and non-mineralized portion appearing peripherally hyperintense.Nidus may be missed however in cortical bone.

Reactive response:

• Cortical thickening and sclerosis shows low SI on all sequences
• Reactive marrow oedema is seen in 63% cases( low signal on T1, high signal on fluid sensitive sequences)
• Periosteal elevation and adjacent soft tissue reactive changes are seen in 50% cases( high signal on fluid sensitive sequences)
• Effusion is seen in intracapsular lesions

Advantages of MR: It shows not only the nidus and surrounding sclerosis, but also the marrow oedema and articular changes.

NUCLEAR MEDICINE FINDINGS:

• Technetium Bone scan shows very intense round activity at nidus and is highly sensitive
• Double density sign: Very intense central activity at nidus surrounded by less intensity of reactive bone
• Round focus helps differentiate from stress fracture which has more linear activity.

DIFFERENTIAL DIAGNOSIS :

• Arthritis:( As in the index patient)
• Osteosarcoma/ Ewing's sarcoma
• Stress fracture
• Chronic osteomyelitis

TREATMENT:

• CT Guied radiofrequency ablation is treatment of choice
• Surgical resection

REFERENCES:

• Manaster BJ: Osteoid Osteoma: Diagnostic Imaging:Musculoskeletal non-traumatic disease. Amirsys.2-26, 2010
• Chai JW et al: Radiologic Diagnosis of Osteoid Osteoma: From Simple to Challenging Findings.  Radiographics; 30(3): 737:49,2010
• emdicine. medscape. com

Giant cell tumour of tendon sheath

T1 and STIR images in coronal plane; T2 GRE, T1 and T2 FS images in axial plane in a 25 year old female reveal a well-defined soft tissue mass along the ulnar aspect of flexor pollicis longus tendon abutting the proximal phalanx of left thumb. It shows hypointense signal on gradient echo image suggestive of paramagnetic substance.


GIANT CELL TUMOUR OF TENDON SHEATH:


This is the second commonest tumour of hand after simple ganglion cyst.


Types: It is of two types, the common localized type and the rare diffuse variety. The diffuse variety is considered the soft tissue counterpart of diffuse PVNS and is more common in lower extermities.


Age: 30-50 years, peak at 40-50 years.
Sex:Female to male ratio is 3:2


Presentation: Commonly occurs along the volar aspect of hand/ finger and is common adjacent to a DIP joint. It presents as a firm, lobulated, non-tender and slow growing mass which is fixed to underlying structures.


Imaging: 
X-ray may show cortical erosion, calcification etc.
USG shows a soft tissue mass along a tendon sheath with vascularity on color/ power doppler.
MRI shows low to intermediate signal on T1 and T2 spin echo sequences due to the presence of hemosiderin. This effect is further exaggerated and blooms on gradient echo sequences.


References:
-Wan JM, Magarelli N, Peli WC, Guglielni G, Sheli TW. Imaging of Giant cell tumour of the tendon sheath. Radiol Med.2010 Feb; 115(1): 141-51
-Verheyden JR. Giant cell tumour of the tendon sheath. emedicine.medscape.com

Lipoma arborescens

T1 and PDFS sagittal images of the left knee of a 27 year old male with history of recurrent joint swelling for the last two years showing frond like synovial thickening in the suprapatellar and posterior parts of the knee joint. The intensity of the frond like synovial thickening is suggestive of fatty tissue.There is significant synovial effusion.

-Lipoma arborescens is a rare condition affecting synovial lining of joints and bursae.
-Usually unilateral
-Most common joint affected-knee
-Rare in other joints like hip, shoulder, wrist. elbow
-There is frond like deposition of fat in the synovial lining.
-Clinical presentation is usually of painless recurrent joint effusion
-MRI is diagnostic as it shows the fatty nature of the fat deposition most commonly in the suprapatellar region of the knee joint.
-Treatment is synovectomy. It usually does not recur after surgery.
- Differentials are: synovial chondromatosis, PVNS, synovial hemangioma, inflammatory arthritis.