Femoral Neck-Aneurysmal Bone Cyst

22 year old male with history of fall and pain right hip. X-ray shows expansile lucent predominantly intramedullary, femoral neck lesion with normal hip joint. MR shows grossly expansile septated, predominantly fluid signal intensity space occupying lesion with cortical breaches, bleed, soft tissue edema in the vicinity – Features are suggestive of aneurysmal bone cyst.

Teaching Points by Dr MGK Murthy, contributors-Mr Hariom Sharma

ABC is non-neoplastic expansile lesion consisting of blood filled spaces separated by connective tissue septa containing bone or osteoid and osteoclast giant cells 

Etiology unknown 

May be primary or secondary ( in about 30 % of associated bone tumors).

CT suggests 20 HU as approximate density with presence of blood and fluid levels.

Double density fluid levels on MR are suggested as quite specific to ABC.

Differential diagnosis includes Simple Bone cyst (Centrally located with no expansion / cortical breach), GCT (more than 20 years of age, no significant expansion and predominantly epiphyseal lesion),  Osteoblastoma (usually diaphyseal, no fluid / fluid levels or cortical breach), Telengiectatic osteosarcoma / Angiosarcoma (difficult to differentiate from agressive ABC).

Developmental Hip Dysplasia-MRI

A 9 month male baby has been felt to have clinically abnormal left hip with possible developmental dysplasia on the frontal radiograph with nondetectable femoral head. MR shows normal left femoral capital epiphysis, with possible delayed ossification ( not seen on the X-ray ) with dislocated position taking it to the upper and the outer quadrants of the intersection of hilgenreiner's line and perkin's lines with disturbed shenton's line with abnormal acetabular angle with normal capsule, labrum, ligamentum teres, iliopsoas tendon with mild free fluid and no AVN. Case submitted by Dr MGK Murthy, Mr Abdul Hamid, and Mr Sahadev Gupta.

Teaching points :

-        Developmental dysplasia of the hip is to be avoided with routine clinical examination at birth.

-        USG is a preferred modality till 6 months of age, when the femoral head shadowing may start interfering with acetabulum image ( femoral head starts ossification between 2 to 8 months ).

-        X-ray is the preferred modality after that with frontal projection and if needed frog leg positions ( Hip in flexion with external rotation )

-        MR is good for identified capsule, labrum, cartilage, presence of AVN and effusion, iliopsoas tendon compression, thick ligamentum teres and pulvinar hypertrophy.

-        Hilgenreiners (HG) line is the horizontal line between two triradiate cartilages.

-        Perkins line is perpendicular to HG and represents outer acetabular margin.

-        Shentons line is an extension of medial femoral metaphysis along the inferior edge of superior pubic ramus.

-        Acetabular angle is normally less than 28 degrees (decreases with age), and is measured as between HG and a line joining superolateral and inferomedial acetabular margins.

TRIANGULAR FIBROCARTILAGE COMPLEX- MRI

Teaching points about TFCC by Dr MGK Murthy & Mr Abdul Hamid

- Normally responsible for ulnar sided wrist pain.

- Thickness is inversely related to ulnar variance with negative ulnar variance patients  having thicker TFCC.

- Normally is 1 to 2 mm thick at most locations with subtle increased upto 5 mm in the vicinity of eccentric concavity of the ulnar styloid.

- Being of type-I collagen is usually dark on all sequences like  the knee ligaement.

- Coronal fat suppressed sequence is most appropriate for study of TFCC.

- The blood supply is usually well maintained at the periphery with relatively avascular centre which leads to central perforations not healing well.

- Dorsal and the palmar branches of the anterior introsseous artery along with dorsal and the palmar branches of ulnar artery supply TFCC. 

- Has attachments to lunate, triquetral, hamate and base of the 5^th metacarpal.

- Closely approximated to extensor carpi ulnaris tendon and associated injuries are common.

- MDCT Arthrography of the wrist  is suggested to be superior in some studies, to MR Arthrography or Conventional Arthrography.

- Degeneration starts in 3^rd decade with heterogenity being the rule by the 4^th decade.

Glenoid Subchondral Cystic Lesion -Approach.

A 23 year old young male after a fall from motor bike complains of chronic pain of 2 months duration. MRI shows a well defined, regular, complex heterogenously altered lobulated completely intraosseous lesion in the subchondral location of the glenoid with no expansion / bleed / labral / cartilage / joint involvement. The differential diagnosis is possibly intraosseous ganglion, post traumatic cyst ( no bleed or fluid / fluid level or heterogenity would make this less likely ), osteoid osteoma ( absence of nidus make this unlikely). Caries sicca ( uncommon location, septal indentification predomiant fluid make this less likely). Case by Dr MGK Murthy and Mr Abdul Hamid.

Teaching points

Intraosseous ganglion cyst are uncommon entities in general with femur and medial malleolus accounting for majority of them, followed by knee and ankle regions. Bone scan / X-ray would suggest presence of activity and no significant calcification.

            

Buford Complex-Normal Variant

 An absent anterior superior labrum and an associated cordl like middIe glenohumeral ligament represent the normal variation that is known as the Buford complex rather than an avulsed labrum. This normal variation may be mistaken for a detached labrum.

Recurrent Dislocation Shoulder- MRI

This patient has a history of previous dislocations, 17 year old  boy with evidence of altered contour and possible periosteal sleeve avulsion involving the anteroinferior labrum with asssociated localized fluid collection in relation to anterior labrum possible labral tear and associated paralabral cyst. Likely ALPSA lesion: anterior labroligamentous periosteal sleeve avulsion. In the Bankart lesion, the anterior cartilage labrum is detached and torn from the periosteum. In the ALPSA, the labral fragment remains attached to the periosteum of the scapular margin and can be tethered in this abnormal position, increasing the likelihood further medial displacement and of re-dislocation.

MR Arthrography Shoulder

Teaching points 

Usually done under fluoroscopy /ultrasonography/CT guidance to avoid labral cartilage injury. By Dr MGK Murthy and Dr Sudheer Kunkunuru

·        Indications

1.   Primarily for Rotator cuff tear suspicion or evaluation

2.   Cartilage evaluation

3.   All the internal structures including glenohumeral ligaments

·        Technique

PreArthrography  Xray shoulder AP with external and internal rotation views to look for presence of hydroxyl apatite crystals/calcification (which could be confused with rotator cuff  tear producing contrast leak)

-Supine and external rotation

-Mark the joint lateral to humeral head cortex

-20 to 22gauge LP needle perpendicular to fluoroscopy beam. Testing the safe INJOINT position with local anaesthetic after aspiration to test for blood vessels

-Confirm position with iodinated  contrast

- Dilute gadolinium injected to the comfort level usually

10 to 16 ml (Cocktail made of 0.1 ml Gadolinium+10ml Iohexol+10ml 0.9%saline+0.3ml of epinephrine of 1:1000 in 20 ml syringe )

Anterior Cruciate ligament Reconstruction – what the Radiologist needs to know?

Young male with history of ACL reconstruction about 1 year back shows good positioning an ligamentization of the  the graft, normal PCL and menisci with subtle free fluid  with too anterior placement of tibial tunnel, post bioabsorbable screws. Case submitted by Dr MGK Murthy, Mr Hari Om, Mr Sahadev Gupta. 

Healthy Graft on MRI should be:

-Low signals if intact unimpinged graft

- Posterior to but not in contact with intercondylar roof

- T1 shows the structure better than T2 because of inherent heterogeneity on T2

-Tibial tunnel should not be too anterior

-Posterior cruciate ligament signals should not be gray/ heterogeneous

(A)        Technical factors evaluation

On X –ray

-fractures/screws integrity or position/union of bony portion/tunnel placement/size of screw tunnel

On MRI

 -Tunnel positioning (common failure is far too anterior placement at tibia )

-Tunnel widening(harmless)

-Graft integrity(heterogeneous signals sign of tear) other soft tissues evaluation

-Femoral insertion  should be at intersection of blumensaat line (intercondylar roof)and extended line from posterior femoral cortex

-Tibial  tunnel should  be posterior and parallel  to tibial intersection of blumensaat line

(B)        Biological factors

-failed ligamentization—not well seen on MRI

-infection

-Arthrofibosis—seen as low signal nodule surrounded by fluid , anterolateral to tibial tunnel called Cyclops lesion on MR (consists of debris of remnant ACL and graft )

-infrapatellar contracture syndrome 

Ganglion Cyst of ACL-MRI

Young male with pain knee joint with lachmann test negative shows a well defined, regular, lobulated, complex fluid signal intensity, space occupying lesion replacing the body and femoral attachment of the ACL with presence of internal septae, with rest of the study unremarkable – Ganglion cyst of the cruciate ligament is likely. Case submitted by Dr MGK Murthy.

Patellar Tendon Rupture-MRI

Young adult with history of  RTA shows complete tear of patellar tendon  midsubstance with involvement of retinacula ,  retraction of patella  with extensive haemorrhage and oedema of the soft tissues with involvement of hoffas  pad of fat. ACL  shows tear as associated finding. Case submitted by Mr Sahadev Gupta, Hariom, Dr Akshay & Dr  MGK Murthy

TEACHING POINTS

• Rectus femoris fibres continue down the anterior aspect of patella  as patellar tendon.
• Vastus lateralis continues as lateral and medialis continues as medial retinaculum and these are often involved in patellar tendon rupture.
• MRI is the modality of choice though high frequency USG would show acute tear as hypoechoic region in experienced hands.
•  Treatment is surgical repair as early as possible and preferably after 4-7 days to reduce the post surgical  infection due haematoma  before that 

Acromioclavicular junction injury-MRI

27 years old male presence with sports injury to the right shoulder. The MR shows disruption of superior and inferior acromioclavicular ligaments with horizontal instability of the joint with marrow edema including the articular margins along with trapezoid component of the coracoclavicular ligament edema suggesting type II / III variety. Case submitted by Dr MGK Murthy and Mr Hari Om.

 

Teaching Points :

• AC joint functions primarily to transmit the weight bearing from axial skeleton to appendicular skeleton with small rotatory movement possible (5 to 20 degrees in various studies).

• Usually occur in contact sports with shoulder and the body falling over the joint in falls on out stretched hand.

• Rockwood classification has 6 types depending of the severity, with type I and II responsible for horizontal instability (anteroposterior) due to superior and inferior acromioclavicular ligament injuries.

• Type III to VI also include vertical in stability due to additional coracoclavicular ligament injury.

• CC ligament has triangular medial component (conoid) and quadrilateral trapezoid component (lateral) with conoid being responsible for anterosuperior stability and the later for posterior stability.

• Usually type I, II and occasionally type III can be managed conservatively, with other types offen requiring surgical procedures.

• Removal of the coracoclavicular screw after some time is needed to permit rotatory movement.

Articular cartilage Defect- MRI

The International Cartilage Repair Society has set up an arthroscopic grading system by which cartilage defects can be ranked:

• grade 0: Healthy cartilage
• grade 1: the cartilage has a soft spot 
• grade 2: minor tears visible in the cartilage
• grade 3: lesions have deep crevices (more than 50% of cartilage layer)
• grade 4: the cartilage tear exposes the underlying (subchondral) bone

On MRI,  FS 3D gradient-echo MRI is helpful for differentiating between grade 3 and grade 4 cartilage defects.

Anterior talofibular ligament (ATFL) Disruption-MRI

Inversion injuries of the ankle account for 40% of all athletic injuries. The anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL) are sequentially the most commonly injured. The axial fat-sat MRI image at the level of the ATF ligament shows loss of the expected low signal band connecting the fibula and talus in this patient.

Tibial Stress Fracture-MRI

Stress fractures are common  in running athletes.  Misinterpretation can result from a similar clinical and radiological early course in stress fractures and bone tumors. We present an athlete with a clinical diagnosis of a meniscus lesion. The following MRI images were reported outside as  for mitotic etiology versus infection.  These images were referred to us for second opinion and a diagnosis of stress fracture or medial tibial stress fracture was suggested. 

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Although medial tibial stress syndrome is one of the most common lower-extremity overuse injuries, its pathomechanics remain controversial. Two popular theories have been proposed to account for this condition: tibial bending and fascial traction- Reference- Journal of the American Podiatric Medical Association. Volume 97 Number 1 31-36 2007

Chikungunya fever & Carpal Tunnel Syndrome-MRI

"Chikungunya fever is a re-emerging viral disease, especially in South India, characterised by abrupt onset of fever with severe arthralgia followed by generalized fatigue, fever, chills, nausea, vomiting, lower back pain and rash lasting for 1-7 days.  Neurologically, encephalopathy is the most common sequela, with alterred sensorium and ataxia.  On MRI, multiple high-intensity areas are seen. There are no spinal cord changes. Other common neurologic manifestations are myelopathy, polyradiculopathy, neuropathy (early > late), and carpal tunnel syndrome (2/2 excess synovial fluid and swelling) as seen in our lady patient who had chikungunya followed by carpal tunnel syndrome. "

Transient bone marrow oedema of the hip-MRI

Transient bone marrow oedema of the hip also referred as transient osteoporosis of the hip is self-limited conditions that improves spontaneously over several months.  TOH was first described in 1959 in two women in their 3rd trimesters of pregnancy but now is more commonly seen in middle-aged men. This is 34 yr old female, immediate post partum, note the bulky uterus and marrow edema involving the right femoral head and neck, along with increased synovial fluid.

Iliopsoas Bursitis/ Tenditis-MRI

The iliopsoas bursa is the largest bursal sac in the body; in 15% of normal individuals, it communicates with the hip joint between the iliofemoral and pubofemoral ligaments.  Iliopsoas bursitis can be caused by various hip joint abnormalities such as joint degeneration, rheumatoid arthritis, PVNS, synovial osteochondromatosis, gout, joint infection, or avascular necrosis. Other possible causes include sacro-iliac joint and adjacent spine pathology.

Distal Radioulnar Joint Subluxation

The radius and ulna constitute a bicondylar joint, articulating at distal and proximal radioulnar joints. Between these two joints, the interosseous membrane functions as a suspension bridge. The stability of proximal and distal radioulnar joints is provided by the thick and complex ligamentous structures, known as the annular ligament and the triangular fibrocartilage complex, respectively. The distal radioulnar joint consists of two articular surfaces that are dissimilar in their radius and curvature, the sigmoid notch and the ulnar seat. MRI is useful to evaluate for TFCC injury and to assess DRUJ subluxation.  Note the positive ulnar variance and widening of the DRUJ space is this case.