Neonatal Hip pathology

Subluxed Hip

Ultrasound image- Longitudinal view showing comparison between the normal right and subluxed left. Note the rounded acetabular lip.

Ultrasound image- Superiorly subluxed hip.

Ultrasound image- During flexion and ADDuction, the hip subluxes. It relocates during Abduction.

Ultrasound image- Subluxed superiorly. Note the rounded/indented ilium-acetabular roof angle (Green). The abnormally elevated labrum (yellow) and femoral head(red circle) would produce an abnormally shallow alpha angle.

Laxity

A neonate with legs in the fixed flexed position secondary to the frank breech lie in-utero.

Ultrasound image- A dual screen image of the infant to the left.

Ultrasound image- The hip abducted.

Ultrasound image- The hip abducted.

Hip Effusion

When a child under 10 years old presents with a limp which only presented acutely such as overnight and they cannot weight bear it should be assumed that they have a hip effusion until proven otherwise.

The capsule may be distended from synovitis or an effusion.

Scanning Technique

  • The child is lying supine with the leg slightly externally rotated. This may prove difficult as the child may be in too much pain.
  • The probe is placed over the hip joint anteriorly along the neck and gently rocked to get parallel to the neck of femur.

Ultrasound image- Hip effusions are seen as fluid that displaces the capsule away from the echogenic cortex of the femoral neck

Ultrasound image- When a hip effusion is identified it is useful to measure the fluid in AP dimensions so that it can be closely monitored to see if it is reducing in size. This is taken between the femoral neck and the capsule. Generally over 5mm is diagnostic of distension.

References

  • http://emedicine.medscape.com/article/408225
  • Hip Sonography: Diagnosis and Management of Infant Hip Dysplasia.2006 Author R.Graf
  • Hip and Knee.Handbook of Pediatric Radiology.1998,301-309 Kriss,V
  • The Pediatric Hip,Diagnostic Ultrasound 1998,2:1799-1814.Rumack,c.Wilson,S.Charboneau,J.W
  • Pediatric Sonography Third Edition 2002. Siegel,M.