Sunday, October 10, 2010

Ultrasound Imaging of the head of neonatal femur and humerus

High resolution Ultrasound images of the normal head of femur in neonate:
 The above image shows the head of the left femur in a 3 day old neonate. Note the full ball of the head of the femur in this transverse section of the femoral head inside the left hip joint. 
 Another neonate- the head of femur is seen a round, hypoechoic structure due to its cartilaginous nature. Note the coarse appearance of the femoral head.

Ultrasound image of the right femoral head (hip joint) - all the above images show the normal head within the acetabulum (socket of the hip joint).                                                                                                                                 
This (above) ultrasound image shows the normal head of the left humerus (in neonate). As in the case of the femoral head images, the head of the humerus is cartilaginous at this young age- hence the hypoechoic, grainy or coarse echotexture. But the humerus shows one major difference- the head forms a "half ball" -a shallow ball and socket joint (the shoulder joint). In infective arthritis of these joints, there would be widening of the joint space with collection of synovial fluid within the joint cavity. Ultrasound is an excellent method of imaging the neonatal hip and shoulder joints.

 The above 3 high resolution (7- 8 Mhz transducer frequency) show the normal right neonatal shoulder joint, from different angles. The transverse section image shows the shallow nature of the glenoid cavity. Sonography of the shoulder joint in the neonate is useful in detecting tendency for dislocation in a baby and ruling out conditions like shoulder dysplasia in infants. By detailed ultrasound imaging one can detect glenoid dysplasia in infant shoulder (a clear indicator of potential shoulder dislocation). This condition is coomon in neonates/ infants with obstetric brachial plexus injury.