Aim: The purpose of this study is to define the hip anatomy in cerebral palsy in a three dimensional geometrical manner and then perhaps plan a better surgical reconstruction for these affected hips.

Materials & Methods: The case notes and radiographs of 18 patients with cerebral palsy who underwent plain radiographs, axial CT and 3D CT scans from October 1993 to June 1995 were reviewed prospectively all being consecutive. The following indices were measured – acetabular anteversion (AA), anterior axial acetabular index (Anterior AAI), posterior axial acetabular index (Posterior AAI), Total axial acetabular index (Total AAI) and acetabular depth/femoral head diameter (AD/FHD) ratio.

Results: The acetabular index, and CEA angle clearly showed the hips to be dysplastic in frontal plane. FAV measurements done on CT scan in our study was 330 on the right and 420 on the left. This was significantly higher than normal in our group of patients. Acetabular anteversion was higher in our series, which contributed to hip instability. There were no patients with acetabular retroversion. The axial acetabular indices suggested predominant anterior than posterior acetabular dysplasia, and the total AAI was suggestive of a flatter and shallower acetabulum. A normal to minimally increased AAI in our study suggests an increase in the size rather than a true malrotation.

Conclusions: Our study shows that CT scan analysis is a useful tool in preoperative planning for hip reconstructions. This analysis gives a better idea of the distorted anatomy and a more accurate quantitative and qualitative assessment of the hips.

This is a retrospective study describing four patients who developed symptomatic subluxation of the hip after stabilisation to the pelvis for myopathic scoliosis in Duchenne Muscular Dystrophy (DMD).

Fusion to the pelvis is recommended for treatment of scoliosis in DMD. Non-spinal extra-pulmonary complications following this have not been described.

4 patients (average age: 14 years) out of a cohort of patients who have undergone spinal stabilisation for DMD between 1991 and 1998 developed symptomatic subluxation of the hip at an average of three months after fusion from the upper thoracic spine to the pelvis. All four had pain and three noticed clicking in the hip.

X-rays revealed subluxation of the hip in all patients, and conservative treatment by adjustment of seating position in the wheelchair was successful in reducing the symptoms in all patients.

Flexion-abduction contractures of the hip, which are a feature of DMD, are known to cause uncovering of the contralateral hip. We postulate that the spine compensates for this uncovering to a large degree, and that spinopelvic fusion for scoliosis in patients with pre-existent abduction contractures negates the capacity of the spine to provide compensation. This leads to uncovering of the hip with the lesser degree of contracture, and the resultant symptoms.

We recommend screening for, and treatment of, flexion-abduction contractures of the hip in all patients undergoing spinal fusion for DMD, to avoid the possibility of development of symptomatic subluxation of the hip.