Related Experiment Video
Updated: May 30, 2026
The Transition to an Anterior-Based Muscle Sparing Approach Improves Early Postoperative Function but is Associated with a Learning Curve
Published on: September 7, 2022
Acetabular deficiency in spastic hip subluxation
Chia Hsieh Chang1, Ken N Kuo, Chao Jan Wang
1Department of Pediatric Orthopaedics, Chang Gung Memorial Hospital, Chang Gung University, Taipei, Taiwan.
Insights
Acetabular dysplasia in spastic hip subluxation is global, with greater deficiency in the anterior aspect. This finding is crucial for selecting appropriate acetabuloplasty methods in children with spastic cerebral palsy.
Area of Science:
- Orthopedics
- Pediatric Orthopedics
- Radiology
Background:
- Spastic hip subluxation is commonly posterolateral.
- The precise location of acetabular deficiency remains debated.
- Accurate definition is key for surgical planning.
Purpose of the Study:
- To determine the degree and location of acetabular deficiency in spastic hip subluxation.
- To inform the selection of acetabuloplasty techniques.
Main Methods:
- 3D CT scans of the pelvis were analyzed in 25 children with spastic cerebral palsy.
- Pelvic CT images were realigned, and acetabular indexes were measured across 9 planes.
- Data from 5 healthy children served as controls.
Main Results:
- Spastic non-subluxated hips showed normal CT acetabular indexes.
- Spastic subluxated hips exhibited significant acetabular index differences compared to normal hips.
- Deficiency was most pronounced in the anterior acetabular regions.
Conclusions:
- Acetabular dysplasia in spastic hip subluxation is a global condition.
- The anterior aspect of the acetabulum demonstrates the greatest degree of deficiency.
- Findings aid in understanding pathology and guiding surgical interventions.
Background:
The direction of spastic hip subluxation is generally agreed to be posterolateral; however, the location of acetabular deficiency is still controversial. This study aims to define the degree and location of acetabular deficiency that is crucial in choosing acetabuloplasty method.
Methods:
Twenty-five children with spastic cerebral palsy, average aged 7.1 years (range, 4.4 to 9.6 y), underwent 3-dimensional computed tomography (CT) studies of the pelvis. Mean Reimers migration percentage of the 50 hips was 32.6% (range, 16% to 66%). Twenty-eight hips were nonsubluxated and the other 22 hips were subluxated (migration percentage > 30%). The 3-dimensional image of pelvis was realigned and a series of 9 section planes were formed to represent the whole iliac root. The CT acetabular indexes were measured and compared to define the deficiency. The data of 5 children without hip problem was retrieved as control.
Results:
Spastic nonsubluxated hips had similar CT acetabular indexes to normal hips. The differences between spastic subluxated hips and normal hips, from anterosuperior to posterosuperior aspects of acetabulum, were 14.8 degrees (A60 degrees), 11.2 degrees (A45 degrees), 10.8 degrees (A30 degrees), 9.9 degrees (A15 degrees), 9.7 degrees (0 degree), 9.5 degrees (P15 degrees), 9.8 degrees (P30 degrees), 9.8 degrees (P45 degrees), and 5.3 degrees (P60 degrees). The differences were significant in all directions and greater in the anterior aspect of the acetabulum.
Conclusions:
The definition of pathology is defined by the deviation from normal physiological status. Acetabular dysplasia in spastic hip subluxation is global and more apparent in the anterior aspect.
Level Of Evidence:
Diagnostic II.
Related Concept Videos
01:16Bones of the Lower Limb: Femur and Patella
01:10Ankle Joint