1. Measuring Ulna Length in Pediatric Neuromuscular Disease
Tina Duong, MPT
Childrens National Medical Center

2. Measuring Ulna Length

3. Diseases included under the pediatric neuromuscular umbrella
Cerebral palsy
Congenital muscular dystrophy
Congenital myopathy
Duchenne muscular dystrophy
Spina bifida
Spinal muscular atrophy

4. Why obtain accurate height measurements in pediatric neuromuscular disease?
To trend growth
To trend and calculate Body Mass Index (BMI)
To trend and calculate conversion from Forced Vital Capacity (FVC) to % predicted Forced Vital Capacity (FVC)
While FVC provides important data, % predicted FVC may demonstrate earlier declines in respiratory capacity.

5. Ulna Length
Measuring height in a uniform manner across all children with pediatric neuromuscular disease allows for:
standard data collection
aggregate data and meta-analysis
ability to reach statistically significant results in rare disease analysis

6. Ulna length serves as a mathematical proxy for height.
Why ulna length?
In children with neuromuscular disease, it can be difficult to obtain an accurate height measurement due to:
Contractures
Scoliosis
Weakness
Ulna length serves as a mathematical proxy for height.

7. Measuring Ulna Length Upper Extremity
Support and position the arm in pronation
with 90 – 110 degrees of elbow flexion.
Palpate the distal tip of the ulnar styloid process
Palpate superiorly on the wrist to avoid mistaking the tendon of the extensor carpi ulnaris for the distal tip of the ulna.
Palpate the tip of the olecranon and place one arm of the segmometer on the olecranon.
Place the other end of the segmometer
at the tip of the ulnar styloid.
Measure in cm, to the nearest
millimeter (e.g. 19.7cm)

8. Where can I find references to calculate height and % predicted FVC based on ulna length?
Gauld LM, Kappers J, Carlin JB, Robertson CF. Height Prediction from ulna length. Dev Med Child Neurol Jul: 46 (7):
Gauld LM, Kappers J, Carlin JB, Robertson CF. Prediction of childhood pulmonary function using ulna length. Am J Respir Crit Care Med Oct 1:168 (7): Epub 2003 Jul 17

9. What device is needed to measure ulna length?
Segmometer