Development of unstable hips after treatment with the Tübingen splint: mid-term follow-up of 83 hip joints.

Abstract

Early diagnosis and treatment of hip dysplasia are widely accepted as major factors for beneficial outcome. However, modalities for reduction and retention as well as for imaging are currently under clinical investigation. Local and general risk factors, e.g., breech presentation and the family's desire to avoid in-hospital treatment are major concerns in the decision-making process and consultation. For treatment of unstable hips in newborns the treatment with the Tübingen splint has proven good results in recent studies. However, mid- and long-term outcome studies are missing. We report on clinical results and X-ray parameter of initially unstable hips after treatment with the Tübingen splint at two time points: 12-24 and 24-48months of age. Included were newborns with 83 unstable hips (type D, III, IV according to Graf) which were successfully treated with the Tübingen splint-used as reduction splint 24h per day/7days per week-until type I hips were documented by ultrasound examination. Measurments are based on routine pelvic X-ray control at the age of 12-24 and 24-48months. The acetabular angle was determined and according to the Tönnis-Classification evaluated into: normal findings (< 1s), slightly dysplastic findings (1-2s) and severely dysplastic findings (> 2s). Children with secondary hip dysplasia were not included in this series. In 2nd year of life, 45 hips (54.2%; initial hip type D: 47.4%, III: 63.2%, IV: 42.9%) of the formerly unstable hips show normal X-ray findings. Although final ultrasound showed normal findings, at this time point 28 hips (33.7%; initial hip type D: 34.2%, III: 31.6%, IV: 42.9%) were slightly dysplastic and 10 (12.0%%; initial hip type D: 18.4%, III: 5.3%, IV: 14.3%) still severely dysplastic. At the age of 24-48months, the percentage of radiologic normal hips had increased to 61 hips (73.5%; initial hip type D: 68.4%, III: 81.6%, IV: 57.1%), the number of slightly (19 hips) and severely dysplastic (3 hips) hips had decreased 22.9% (initial hip type D: 28.9%, III: 15.8%, IV: 28.6%) respectively 3.6% (initial hip type D: 2.6%, III: 2.6%, IV: 14.3%). At this time no operative intervention was neccessary. Our mid-term data show on the one hand a good development of unstable hips after successful treatment with the Tübingen splint. On the other hand despite successful therapy and normal ultrasound findings at the end of treatment further imaging by X-ray are mandatory to close follow-up and to detect those which might need surgical correction of residual dysplasia.