Ultrasound guided injection of the lateral cutaneous nerve of thigh

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

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

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

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)

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

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

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%).

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

  • 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

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

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.

de Quervain tenosynovitis, 1st CMCJ osteoarthritis

Imaging LCL (lateral collateral ligament) of the knee

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

Medial (Tibial) Collateral ligament injuries:

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

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

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

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
'Rat bite' from adjacent tophi
Mushrooming/ bulbous appearance of the bone ends

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

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

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

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

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

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

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


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)

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