Keywords:
Diagnostic procedure, Ultrasound, Elastography, Conventional radiography, Musculoskeletal joint, Cerebral palsy
Authors:
H. Aslan, P. D. Analan; Adana/TR
DOI:
10.1594/essr2018/P-0020
Purpose
Hip dislocation in children with cerebral palsy (CP) is a common and severe problem.
It results in significant morbidity in terms of pain,
postural difficulty,
ambulation,
disability and lower-extremity fractures.
Abnormal muscle forces and muscle imbalance around the hip are believed to be the underlying cause of hip displacement by shifting the mechanical axis of the hip (1).
Particularly hyperactivity of the hip flexors and adductors are reported as the contributing factors (2).
In 1980,
Reimers defined the migration percentage (MP) to document the extent of hip subluxation lateral to the acetabulum.
Measuring the percentage of hip migration with an anteroposterior radiograph is the best way to determine the degree of subluxation or dislocation of the hip joint (3).
It is still used as the key tool to monitor,
make decisions of preventive interventions or surgery and determine the progression of subluxation (4-7)
Reimers’ hip migration percentage (MP) is commonly used to examine the amount of lateral displacement of the femoral head in children with CP (3).
An MP < 33% is considered as normal. In children with an MP between 33% and 40%,
treatment based on other clinical signs including the follow-up progression of the MP over time is recommended (4,
6).
Progression of the MP greater than 7% per year is considered to be worrying (4).
Hips with an MP of ≥40% indicate the need for surgical intervention.
Shear Wave Elastography (SWE) is an Ultrasound (US) based technique which provides a quantitative measurement of the tissue stiffness by producing “push pulses” which result in shear wave propagation in the tissue.
Migration percentage is the percentage of the femoral head that sits outside the lateral margin of the acetabulum.
In this study we aimed to assess the correlation between the MP and the stiffness of the hip muscles by SWE.
Our second aim was to assess the correlations between the stiffness of hip flexor-extensor and abductor-adductor muscles.