Musculoskeletal Radiology

Ultrasound guided injection of the lateral cutaneous nerve of thigh

2012-09-21T13:41:00.000+01:00

Anatomical landmark:
1 inch (2.5 cm) medial and inferior to ASIS

Ultrasound identification:
Keep the probe transverse just below the anterior superior iliac spine (ASIS)
Sweep medially and inferiorly
No probe pressure (otherwise the two fasciae collapse)
Lateral femoral cutaneous nerve is seen between fascia lata and fascia iliaca. fascia iliaca is superficial to sartorius
Commonly found approximately 10-25 mm medial and 45-85 mm inferior (average 2 inch/ 5 cm) to ASIS, and 6 mm (5-7 mm) deep to the skin

Reference:
Ng I, Vaghadia H, Choi PT, Helmy N.Ultrasound imaging accurately identifies the lateral femoral cutaneous nerve.Anesth Analg. 2008 Sep;107(3):1070-4.

Assessment of capsular laxity

2012-03-27T12:21:00.000+01:00

Permanent functional lengthening of the anterior capsule leads to instability.

Types of capsular attachment:
Type 1: anterior capsule (MGHL) inserts into labrum
Type 2: anterior capsule inserts within 1 cm of labrum
Type 3: anterior capsule inserts more than 1 cm from labrum
Type of capsular attachment has no role in prediction of shoulder instability

Anterior capsule:

Neutral/ internal rotation position: capsule is lax
ABER: Capsule tightens
Best measured on oblique sagittal sequences from the glenoid centre.
No significant difference in two positions, i.e, loss of capsular tightening, indicates lax capsule

Reference:
1. Ng AWH et al. Assessment of capsular laxity in patients with recurrent anterior shoulder dislocation using MRI. AJR 2009: 192: 1690-1695
2. Palmer WE et al. Anterior shoulder instability: diagnostic criteria determined from prospective analysis of 121 MR arthrograms.December 1995 Radiology, 197, 819-825.

Frozen shoulder (Adhesive capsulitis)

2012-02-17T14:17:00.000+00:00

Fluroscopy:
Limited capacity to inject
Small axillary fold
Irregularity of anterior capsular insertion at humeral neck

MR arthorgraphy:
Thick axillary recess > 4 mm on oblique coronal
Smaller volume of the axillary recess
Thick joint capsule: at rotator interval > 7 mm
Thick CHL > 4 mm
Subcoracoid triangle sign: obliteration of fat triangle between CHL and coracoid process
Synovitis like abnormality in the rotator cuff tendons

Reference:
Mengiardi B et al; Frozen Shoulder: MR Arthrographic Findings; November 2004 Radiology, 233, 486-492.
Eric W et al. Adhesive Capsulitis of the Shoulder: MR Diagnosis;AJR 1995

medial ligament complex pathology

2012-02-15T12:04:00.002+00:00

For anatomy click this link

Less common compared to lateral ligament complex injuries.
Isolated medial ligament complex injury is RARE.
Usually associated with medial malleolar fracture or oedema,lateral ligament complex injury, fibular fracture, syndesmosis injury (in 10%).

Grading:
Grade 1: Stretch injury
Grade 2: Partial tear
Grade 3: Complete disruption

MR:

Increased T2 signal of the ligament complex
Intermediate intersitital signal on T1 and PD, and increased T2 signal
Medial malleolus and medial talar oedema
Lateral talar oedema!!
Lateral or posterolateral talar displacement
Haemorrhage
Fluid filled gap = complete disruption
Dystrophic ossification (chronic)

Intersection syndrome

2012-01-18T15:50:00.000+00:00

Tenosynovitis of extensor carpi radialis longus (ECRL), and extensor carpi radialis brevis (ECRB).

Anatomy:
The tendons of first compartment (APL & EPB) pass superficially obliquely over ECRL and ECRB in the 2nd compartment at musculotendinous junction. This intersection occurs dorsoradially at the junction of the middle and distal thirds of the forearm, just proximal to the extensor retinaculum.

Differentials:
de Quervain tenosynovitis, 1st CMCJ osteoarthritis

Imaging LCL (lateral collateral ligament) of the knee

2011-09-24T02:19:00.002+01:00

Lateral (Fibular) collateral ligament injuries:

Usually part of posterolateral corner injury
Middle third is most commonly involved
Coronal MR is best with accuracy nearing 100%

Imaging MCL (medial collateral ligament) of the knee

2011-09-24T02:18:00.000+01:00

Medial (Tibial) Collateral ligament injuries:

Commonly involves the proximal portion of the ligament near the femoral attachment site.

Grading:
Grade I sprain: contour irregularity, edema superficial to MCL. Fibers remain intact.
Grade II injury: partial tear: partial discontinuity of the fibers, adjacent areas of abnormal signal. Some fibers remain intact.
Grade III injury: complete disruption: complete discontinuity of MCL fibers, extensive surrounding signal abnormality.

Gouty arthritis

2011-09-23T13:36:00.000+01:00

Deposition of MonoSodium Urate (MSU)
> 40 years
Male > female

Tophus:
Hallmark of gout
Tophus = urate, protein matrix, inflammatory cells and gaint cells
Tophus seen in intra-articular (synovial) space, periarticular subcutaneous tissue, tendon, ligament, cartilage, bone, bursa
Common areas: olecranon bursa, ear, nose, meniscus, quadriceps tendon, patellar tendon, Achillis tendon (may lead to tendon rupture)
Subcutaneous tophi may ulcerate or may produce saucerization of the bone

Key points:
Most common joint: 1st MTPJ
Next common sites: IPJ of the big toe, TMTJs
Typically monoarticular
When polyarticular: asymmetric
Pedilication for extremity joints, lower limb more common than upper limb
Axial joints rarely affected
Can lead to carpal tunnel syndrome, trigger finger, discitis, paraplegia

Plain film:
5-10 year delay in first radiographic presentation!
Earliest: soft tissue swelling
Then: fine lacy periosteal reaction (this is actually urate crystals adjacent to the cortex)
Faint calcification in the soft tissue (tophi), seen in 50%
Intracortical erosion and irregularity
Osteochondral compression/ cupping
JUXTRA ARTICULAR PUNCHED OUT EROSIONS WITH SCLEROTIC MARGINS AND OVERHANGING MARGING (seen late, but characteristic)
'Rat bite' from adjacent tophi
Mushrooming/ bulbous appearance of the bone ends

JOINT SPACE IS PRESERVED TILL LATE
NO periarticular osteopenia (diffuse osteopenis - late in disease)
Introsseous tophi - seen as cysts (rarely sclerotic lesion)
Very late: pencil-in-cup, subluxation, bone infarct, arthritis mutilans, ankylosis

USG:
Three times sensitive to detect erosions of smaller than 2 mm, compared to plain radiograph
'Double counter sign' - hypperechoic, irregular band over the articular cartilage (secondary to MSU deposit)
Hyperechoic soft tissue +/- posterior shadowing
'Snow-storm synovial effusion'
Synovial hypertrophy
Increased vascularity
Tophi - hypo-to-hyperechoic, heterogenous, thin anechoic rim

CT:
Tophus as hyperdense mass (>160 HU)
Dual energy CT (80 and 140kV) can assess the chemical composition
Superior to MR in detection of erosions!

MRI:
Early detection of tophi
Synovial thickening
Joint effusion
Bone erosion
Bone marrow edema
Tophi: homogenous, low-to-intermediate on T1 and T2, and nehance intensely

Reference:
1. S. Dhanda, A re-look at an old disease: A multimodality review on gout, Clinical Radiology, Volume 66, Issue 10, October 2011, Pages 984-992
2. Learning radiology

Get a kick out of this: the spectrum of knee extensor mechanism injuries -- Tuong et al. 45 (2): 140 -- British Journal of Sports Medicine

2011-01-25T13:08:00.000+00:00

Get a kick out of this: the spectrum of knee extensor mechanism injuries -- Tuong et al. 45 (2): 140 -- British Journal of Sports Medicine

A good free article!

Common sports injuries in Young

2011-01-25T10:04:00.000+00:00

Calcaneal Apophysitis:

Young children.

Shin Splint (Medial Tibial Stress Syndrome)

pain along medial aspect of tibia

Patellofemoral Stress Syndrome

tenderness over medial facet of medial patella.

due to poorly developed vastus medialis and tight hamstrings.

Quadriceps Contusion

pain in thigh.
palpable mass at site of pain
Complication: myositis ossificans

Rotator Cuff Tendinosis

Lateral Ankle Sprain

Spondylolysis

Medial Epiphysitis (Apophysitis)

Tennis elbow is rare in children, hence exlude fracture before making this diagnosis

Iliac Apophysitis

pain in iliac crest

Iliotibial Band Friction Syndrome (Iliotibial Band Bursitis)

Reference:

LAIRD HARRISON, Elsevier Global Medical News, Tackling the Top 10 Sports Injuries

Crisp-padhiar syndrome

2011-01-23T21:17:00.000+00:00

Post-traumatic medial midfoot pain
Tibialis posterior tendon tendinopathy
Os naviculare syndrome
Stress fracture of navicular and Lisfranc ligament injury
Acquired flatfoot
Os naviculare synchondrosis
Anomalous tibialis posterior tendon attachment of Os naviculare.

Reference:
Crisp-padhiar syndrome -- Crisp et al. 45 (2): e1 -- British Journal of Sports Medicine:

Cortical Desmoid

2011-01-23T20:05:00.000+00:00

Irregular lucency in medial supraconsylar ridge (posteromedial aspect of the distal femoral metaphysis), secondary to chronic avulsion injury of the adductor magnus aponeurosis.

Common in adolescent
Pain, or asymptomatic
May or may not show periosteal reaction
Mixed sclerosis and lucency in the cortex
Self limiting
Bilateral in 1/3rd
Low signal on T1, increased signal on T2, and may enhance with Gd

A case with good MR images
Another case
Review article: MR features of cortical desmoid

Scoliosis Imaging: What Radiologists Should Know — RadioGraphics

2011-01-07T15:34:00.000+00:00

Scoliosis = lateral spinal curvature with Cobb angle of 10° or more.

Classification:
A. Idiopathic: 80%; infantile, juvenile and adolescent
B. Associated with
1. Vertebral anomaly
2. Neurological anomaly
3. Skeletal dysplasias
4. Neuromuscular diseases
5. Bone tumours
6. CNS or PNS tumours

Scoliosis Imaging: What Radiologists Should Know — RadioGraphics

Ulnar sided impaction syndromes

2010-08-27T10:54:00.002+01:00

Ulnocarpal abutment syndrome:
= Ulnar impaction syndrome, Ulnar abutment, Ulnocarpal loading
Most common cause of ulnar sided impaction

Predisposing factors:
Positive ulnar variance, distal radial malunion, unrecognised DRUJ derangement

Imaging:
Positive ulnar variance (pronation and firm grip view can increase ulnar variance by 1-2 mm)
Chondromalacia of ulnar head, lunate and triquetral, subchondral degenerative changes later
Central perforation of TFC
Lunotriquetral ligament tear
End stage: OA of ulnocarpal joint and DRUJ

Distal radioulnar impingement syndrome
= Ulnar impingement syndrome:
Causes: surgery (e.g., Madelung deformity correction), RA, trauma, negative ulnar variance
Shortened distal ulna (proximal to sigmoid notch), impinging on the distal RADIUS (not carpal bones), proximal to sigmoid notch
Erosive changes to scalloping of distal radius
Radioulnar convergence

Ulnocarpal impaction secondary to ulnar styloid non-union:
Fracture ulnar styloid
Type 1: Intact TFC and stable DRUJ
Type 2: Avulsion of ulnar attachement of TFC (Palmer IB) with DRUJ instability
Chondromaclia, subchondral changes in the triquetral bone

Ulnar styloid impaction syndrome:
Excessively long ulnar styloid more than 6 mm
Ulnar styloid process index of more than 0.28 (Length of ulnar styloid – ulnar variance/ transverse diameter of ulnar head)

Chondromaclia, subchondral changes in the triquetral and ulnar styloid

Hamatolunate impingement syndrome:
Type II lunate bone (lunate articulates with hamate)
Chondromlacia, subchondral changes in the proximal pole of hamate

Reference:
1. Cerezal et al. Imaging findings in ulnar sided writst impaction syndromes

Ultrsaound of hernias

2010-08-26T16:02:00.000+01:00

Inguinal region:

Anterior wall: external oblique aponeurosis; inguinal ligament more anteriorly
Posterior wall: transverse abdominus and part of internal oblique

Deep/internal inguinal ring:
Defect in transversalis fascia
Lateral to inferior epigastric artery
Above inguinal ligament

Superficial/external inguinal ring:
Defect in external oblique aponeurosis and inguinal ligament, immediately superior and lateral to pubic tubercle

Inferior epigastric artery:
Originates from EIA proximal to inguinal ligament
Passes medial to deep inguinal ring
Within the investing fascia of rectus abdominis, deep to rectus abdominis

Inferior epigastric artery and inguinal ligament divide inguinal region into 3 anatomic areas:
1. Hesselbach's triangle or inguinal canal: inferiorly by inguinal ligament, medially by lateral margin of rectus abdominis, and superolaterally by inferior epigastric artery
2. Femoral region: inferior to medial aspect of inguinal ligament
3. Region lateral to inferior epigastric artery and just above the inguinal ligament

Conjoint tendon:
Condensation of internal oblique and transversus abdominis aponeuroses

Lacunar ligament:
Reflection of the inguinal ligament

Four weak areas = 4 hernias:
1. Deep inguinal ring = indirect inguinal hernia
2. Inferior aspect of Hasselbach’s triangle = direct inguinal hernia; situated just lateral to conjoint tendon and medial to the inferior epigastric artery
3. Inferior to inguinal ligament and lateral to lacunar ligament = femoral hernia, medial to femoral vessels
4. Lateral margin of rectus abdominis muscle, superior to inferior epigastric artery as it crosses linea semilunaris = spigelian hernia

Relationship of hernia to inferior epigastric artery:
Hernia arising lateral to inferior epigastric vessel = indirect = passing thru inginal canal
Hernia arising medial to inferior epigastric vessel = direct = bulging thru posterior wall

Technique:
Don’t apply pressure.
Slow valsalva = slow strain. No coughing.

Transverse oblique plane:
Identifying deep inguinal ring:
1. Transverse oblique scan of rectus abdominis – identify inferior epigastric vessels deep to rectus within investing fascia
2. Transverse oblique scan of femoral vessels - move cranially to see origin of inferior epigastric vessels
Deep inguinal ring lies lateral to inferior epigastric vessels.
Medially symphisis pubis and laterally inferior epigastric vessels.

Short axis = sagittal plane:
Identify femoral artery in longitunal plane – move medially to identify inferior epigastric vessel – as they pass superiorly towards rectus abdominis, move more medially.

Inguinal canal is seen as ill-defined oval shaped area with hypoechogenic tubular structures.

In men, spermatic cord (heterogeneous hyperechoic structure with hypoechoic tubules and vascularity) is seen originating from the internal inguinal ring

Valsalva leads to narrowing of inguinal canal, distension of the femoral and inferior epigastric vessels, distension of vessels within the inguinal canal

Indirect inguinal hernia:
Thru inguinal canal
Persistent processus vaginalis seen in 30% adults
Can be extensive and protrude thru external ring
Superior to inguinal ligament
Transverse plane:
Lateral to inferior epigastric vessels
Extends thru the long axis of inguinal canal
Sagittal plane:
Distends canal in valsalva, effacing the contents

Direct inguinal hernia:
Usually in the inferior aspect of Hesselbach's triangle (H)
Protrude from posterior inguinal wall within transverse abdominis fascia
More localized
Transverse plane:
Medial to inferior epigastric vessels
Sagittal plane:
Comes from posterosuperior aspect into the canal

Femoral hernia:
Lateral to lacunar ligament, inferior to inguinal ligament
Transverse scan thru femoral vessels, valsalva leads to distension of femoral vein. Hernia, if any, will be seen, and may prevent normal expansion of the femoral vein

Spigelian hernia:
Along the linea semilunaris, just superior to inferior epigastric artery as it passes deep to lateral border of rectus abdominis muscle

Reference:
1. Jamadar DA et al. Sonography of inguinal region hernias. AJR 2006; 187: 185-190
2. McNally EG. Practical musculoskeletal ultrasound. Elsevier publication. 2005

ACJ injury

2010-05-04T09:17:00.000+01:00

Allam and Tossy:
Grade 1: mild sprain, normal radiograph, increased T2 signal on MR.
Grade 2: moderate sprain, less than 50% on radiograph, fluid outside joint capsule on MR.
Grade 3: complete disruption, widening of joint with more than 50% displacement on radiograph, displacement.

Rockwood:
Type I: mild AC ligament sprain, intact CC ligament, joint capsule, deltoid, trapezius muscle, no clavicle elevation.
Type II: ruptured AC ligament, sprained CC ligament, ruptured joint capsule, minimally detatched deltoid and trapezius, clavicle less than 50% of joint height
Type III: ruptured AC and CC ligament and joint capsule, detached trapezius and deltoid, clavicle elevated more than 50% of joint height
Type IV: III + clavicle displaced posteriorly into trapezius
Type V: III + clavicle elevated superiorly more than 100% of joint height.
Type VI: III + clavicle inferiorly displaced behind coracobrachialis and biceps tendons

Baastrups's disease

2010-03-31T16:40:00.000+01:00

Close approximation of spinous processes = kissing spines
Bursae between the spines on MR

Post arthroscopy fibrosis

2010-03-19T09:58:00.002+00:00

Common route of entry in arthroscopy: anterolateral, anteromedial, central
Focal thickening of the patellar tendon
Focal linear low signal on all sequences

Localized nodular synovitis

2010-03-19T09:57:00.000+00:00

Localised form of PVNS of Hoffa's fat
Similar to giant cell tumor of tendon sheath
localised mass in the synovium or Hoffa's fat
hemosiderin (blooming) and/or fibrosis can give low signal on all sequences

Intracapsular chondroma

2010-03-19T09:55:00.000+00:00

Also known as extraskeletal ossifying fibroam, intracapsular osteochondroma, soft tissue osteochondroma
Rare
Located inferior to patella
Come consider this as end stage Hoffa's disease
Heterogenous mass
Plain film: chondroid or osseous matrix

Imaging UCL of 1st MCPJ

2010-03-16T12:04:00.000+00:00

Anatomy:
Capsule, volar plate, UCL, RCL, EPB tendon, adductor pollicis aponeurosis

UCL tear:
Also known as gamekeepers' thumb
Mechanism: forceful abduction
Most common site: distal rupture, and the ligament is retracted proximally

True coronal plane through 1st MCPJ is essential
UCL is retracted
If deep to adductor aponeurosis, its simple rupture (game keepers' thumb)
If superficial to adductor aponeurosis (entrapped by adductor pollicis aponeurosis), its Stener's lesion
Other changes: avulsion fracture, volar subluxation of the joint

Stener's lesion:
Occurs in about 50% of complete UCL tears
Common in skiers

Grading:
Gr 1: ligament strain/ stretch
Gr 2: incomplete tear
Gr 3: complete rupture +/- Stener's lesion

Complications of ACL reconstruction

2009-12-09T15:59:00.000+00:00

Graft anatomy:
Autologous bone–patella tendon–bone graft
Autologous four-strand hamstring graft = doubled semitendinosus and gracilis tendon graft
Replace the anteromedial bundle (AMB) only

Femoral tunnel:
Sagittal plane: line along posterior cortex of the femur and line along the roof of the intercondylar notch. Inferior portion of the tunnel to be located at intersection of these two lines

Coronal plane: intraarticular portion of the femoral tunnel should open at the superolateral posterior margin of the intercondylar notch, i.e., between 10 and 11 o'clock in right knee and between 1 and 2 o'clock in left

Tibial tunnel:
Sagittal plane:
Tibial tunnel should be parallel and posterior to Blumansaat's line (line drawn along the intercondylar roof)
Distal portion of the tunnel near tibial tuberosity
Intraarticular opening completely posterior to intersection of Blumensaat line and tibia
Lucency is common around the graft and sclerosis at the tunnel margins on follow-up are normal finginds
Coronal plane:
Tibial tunnel should open at intercondylar eminence

Normal ACL graft:
Low signal; intermediate signal bet 4 to 8 months, resolve by 12 months

Graft failure: Early failure: within 6 months, most due to poor technique
Late failure: after 1 year, most due to repeat trauma leading to graft tear

Complications:
Roof impingement
Partial tear
Complete tear
Arthrofibrosis (cylops)
Tunnel cyst
Iliotibial band syndrome
Hardware complications: displacement, fracture
Infection

Roof impingement:
Usually secondary to abnormal tibial tunnel
Graft is shown in contact with anteoinferior margin of intercondylar roof
Graft may show posterior bowing

Partial tear:
Focal increased signal in graft
Differential would include 'normal ligamentization'

Complete tear:
Most are due to trauma
Direct visulization of tear
Indirect signs: large effusion, pivot shift bone contusions, fluid filled graft defect, horizaontal orientation of graft, laxity of graft

Arthrofibrosis:
Scar in at least one compartment
Cylops (focal): anterior arthrofibrosis is nodular
Increased incidence in ACL reconstruction within 4 weeks of trauma
Diffuse:

Tunnel cyst:
Small fluid signal within tunnel in 1st year is common, and is disppears by 18 months
Tibia far more common than femur

Reference:
Bencardino JT et al. MR imaging of complications of anterior cruciate ligament reconstruction. Radiographics 2009;29;2115-2126

Imaging Annular Ligament of the elbow

2009-08-04T12:48:00.003+01:00

It is a ring surrounding radial head, attached to anterior and posterior margins of radial notch of ulna
Complex formed from capsule, lateral collateral ligament complex (LCLC) and supinator muscle
Tight superiorly, loose inferiorly
Best shown on axial and sagittal MRA
Anterior attachment: single band, broader
Posterior attachemnt: single to 4 bands (hence should not be mistaken for pathology)
On sagittal: funnel shaped, wider proximally, and narrow distally at radial neck

Nursemaid's elbow:
Transverse tear of the distal attachment of annular ligament is likely to be the first step.

Reference:
1. Sanal HT et al. Annular Ligament of the Elbow: MR Arthrography Appearance With Anatomic and Histologic Correlation. AJR 2009; 193:W122-W126

Trochanteric bursitis (greater tuberosity pain syndrome)

2009-02-11T14:31:00.003+00:00

Anatomy:
Facets on greater trochanter: anterior (gluteus minimus), lateral , posterior and postrosuperior
Gluteus minimus attaches to anterior facet
Gluteus medius attaches to lateral and posterosuperior facets
Bursae: trochanteric bursa, subglutues minimus bursa, sub gluteus medius bursa

Pathology:
Tear in the abductor tendon
Abductor tendinopathy
Bursitis

MRI:
Increased T2 signal within the tendon
Partial or full thickness tear
Muscle atrophy in chronic tears
GLuteus medius is more frequently involved

Link:
http://www.radsource.us/rf/RADS/Internal.aspx?PID=486

Internal impingement of the shoulder

2009-02-06T16:18:00.003+00:00

Also called posterosuperior impingement
Impingement of posteriorsupraspinatus or anterior infraspinatusor both between humeral head andposterior glenoid during extreme abduction and external rotation(overhead movement)
Secondary to abnormality in the supraspinatus, infraspinatus, posterosuperior labrum or humeral head or combination of above

Arthroscopic criteria:
Posterosuperior labral fraying or tear
Articular irregularity of supraspinatus or infraspinatus orboth
Contact of cufftendons on posterosuperior glenoid in abduction and external rotation

MRI:
Irregularity of undersurfaceof rotator cuff - abnormal signal, tears or both
Capsular laxity with anteriortranslation of humeral head
Frayingor tear or both of posterosuperior labrum
Cyst like change posterolateral humeral head at attachment of infraspinatus tendon and posteriorfibers of supraspinatus (may be secondary to impaction or traction).

References:
1. Giaroli EL et al. MRI of Internal Impingement of the Shoulder. AJR 2005; 185:925-929