Background
Glenohumeral instability is a known complication of congenital brachial plexus palsy. In certain cases, muscle imbalance leads to posterior displacement of the head of the humerus on the cartilaginous glenoid, resulting in glenoid dysplasia and varying degrees of joint subluxation. Studies using ultrasonography have demonstrated that these anatomical changes occur in the early months of life and can be reversed with prompt treatment. However, the technical challenge of obtaining standard ultrasonography in a child a few weeks old is considerable. The subject is small, mobile and unable to sit unsupported. The shoulder that is being examined must be fully exposed with the upper limb free to move in order to obtain dynamic imaging. We had previously tried several methods of supporting the baby in order to facilitate the examination to no avail until it occurred to us to use a simple proprietary seating aid.
Technique
The Bumbo® floor seat (Bumbo International Trust, Pretoria, South Africa) was designed to seat babies who are unable sit up by themselves. It stabilises the child into slight hip flexion, placing the pelvis in a slight anterior tilt, facilitating lumbar extension (Fig 1). When placed in one of these seats, the child adopts an upright position with access to the entire shoulder. The parent sits facing the child and can help to distract or comfort the baby. In very young subjects, the parent can also provide head support.
Figure 1.
Child in Bumbo® seat
Discussion
This simple technique facilitates execution of a procedure that is otherwise rather time consuming and difficult. Correctly positioning the child in one of these seats optimises acquisition of images, thereby aiding the diagnostic process.