Deformities of the hip in cerebral palsy were second most common deformities encountered. They were caused by an imbalance of muscle power, retained primitive reflexes, habitually faulty posture, an absence of weight bearing stimulation on the bones, and growth.

During the period of March 1990 through June 1993, we evaluated 123 cerebral palsied children about their neuromotor type, topography, severity, and hip and pelvic deformities by physical examination and pelvic X-ray study in an institutionalized center for severely disabled children.

The results were as follows:

1) The neuromotor type distribution was spastic in 54.5% (67/123), athetoid in 26.0% (32/123), mixed in 14.6% (18/123), and hypotonia in 4.9% (6/123). The severity was to a mild degree in 3.3% (4/123), a moderate degree in 21.1% (26/123), and a severe degree in 75.6% (93/123). The topographic distribution of spastic type was hemiplegia in 16.4% (11/67), triplegia in 4.5% (3/67), quadriplegia in 58.2% (39/67), and diplegia in 20.9% (14/67).

2) Among 246 hips of 123 children, the frequencies of hip and pelvic deformities were; hip subluxation or dislocation in 27.6% (34/123) with 28 hip subluxation (13 right, 15 left, & 5 bilateral) and with 13 hip dislocations (9 right & 4 left); acetabular dysplasia in 36.6% (45/123) with 59 hips (30 right, 29 left, & 14 bilateral); pelvic obliquity in 16.3% (20/123) with 20 pelvis (11 right & 9 left); and increased femoral anteversion in 46.3% (57/123) with 95 femurs (45 right, 50 left, & 38 bilateral).

3) The mean of acetabular indexes were 18.8±7.7^o in right and 19.5±8.3^o in left.

4) Among 45 children (36.6%) with acetabular dysplasia, right hips were 30 cases and left hips were 29 cases, 30 right acetabular dysplasias were normal in 8.9% (9/101), had subluxation in 100.0% (13/13), and had dislocation in 89.9% (8/9), with 29 left acetabular dysplasias were normal in 9.6% (10/104), had subluxation in 100.0% (15/15), and had dislocation in 100.0% (4/4). Then, a high frequency of hip subluxation or dislocation in cerebral palsy with acetabular dysplasia was significant, when compared to cerebral palsy without acetabular dysplasia (p=0.000).

5) Among 34 children with hip subluxation or dislocation, the frequencies of neuromotor type in cerebral palsy were spastic (include mixed) in 82.4% (28/34) and nonspastic (include athetoid & hypotonia) in 17.6% (6/34). The frequency of spastic types in cerebral palsy with acetabular dysplasia was significantly high, when compared with nonspastic types (p=0.04938).

6) The incidence of hip subluxation or dislocation among 45 children with acetabular dysplasia was 71.1% (32/45). They were spastic in 65.6% (21/32), athetoid in 15.6% (5/32), mixed in 18.8% (6/32), and hypotonia in 0%. Then, a high frequency of hip subluxation or dislocation in cerebral palsy with acetabular dysplasia was more significant in spastic types than with other types (p=0.005).

7) The children with increased femoral anteversion were 59.7% (40/67) in spastic, 31.3% (10/32) in athetoid, 22.2% (4/18) in mixed, and 50.0% (3/6) in hypotonia. Then, a high frequency of increased femoral anteversion was more significant in spastic & hypotonia than in other types (p=0.00744).

8) The 19 children (15.4%) with above 26^o of right acetabular indexes were 66.7% (6/9) in dislocation, 53.8% (7/13) in subluxation, 15.6% (6/101) in normal hips, and the 24 children (19.5%) with above 26^o of left acetabular indexes were 100.0% (4/4) in dislocation, 60.0% (10/15) in subluxation, 20.3% (10/104) in normal hips. Then, a high frequency of dislocation or subluxation was more significant in above 26^o of acetabular index than in below 25^o of acetabular index (p=0.000).

We recommand regular physical examination and pelvic X-ray study every 3-6 months for early detection and treatment of the hip and pelvic problems in cerebral palsy.