CLOSED REDUCTION OF LATE-PRESENTED DDH: MRI VIEW OF REMODELLING

Abstract

Treatment for developmental dysplasia and dislocation of the hip (DDH) presenting after one year of age is controversial. There are advocates of both open and non-operative reduction. Surgeons advocating open reduction believe in excising the obstructing soft tissues for all such cases. Others reducing non-operatively suggest that pressure from a reduced femoral head provides gradual concentric reduction with remodelling of the restraints. MR images of hips in a group of patients treated non-operatively were examined to determine the long-term development of the soft tissue around the hip.

We have been treating late presented DDH by graduated traction and gentle manipulation under general anaesthetic since 1975. 10 (12 hips) of these patients were consented to have an MRI Scan of their hips. Mean age of presentation was 17 months (13–36 months). Mean follow up was 16 years (7–26 years). Mean duration of traction was 31 days (16–45 days). None of the hips had an open reduction. Subsequently 3 hips had a femoral osteotomy at a mean age of 5. 9 years (4. 1–7. 8) and 3 hips underwent a Salter-type osteotomy at a mean age of 4. 3 years (3. 7–5. 4).

According to the grading of Barrett et al, 9 hips were graded clinically excellent, 2 were good and 1 hip was fair. The latest radiological result was graded according to Severin. There were 9 grade 1 hips, 2 grade II hips and 1 grade III.

All the patients had coronal, sagittal and transverse scans of both their hips. All the MRI Scans showed a good coverage of the femoral head. Anterior and posterior acetabular cover was adequate in all the hips. Osseo-cartilaginous extension beyond the acetabular margin was constantly found in all the hips. Even in the hip with a Severin score of III, the cartilaginous acetabular extension produced a concentric hip joint. The anterior and the posterior labrum were found to be well developed in all the hips. None of the hips showed any evidence of inverted limbus. 3 hips showed mild evidence of avascular necrosis but there was no evidence of collapse or flattening. Thinning of the articular cartilage was seen in 3 hips but no mechanical changes observed. Capsule and ligamentum teres were found to be well developed and non-obstructive.

Long-term results of non-operative treatment of late presented DDH have been found to be satisfactory. The MRI scans have shown an excellent soft tissue remodelling around the hip. Soft tissue restraints preventing initial reduction in late-presented DDH are therefore not an absolute indication for open exploration. MRI scans were found to be an excellent tool to study the effect of soft tissue remodeling in such cases.