Abstract
In this thesis, we showed that the incidence of (late) DDH increases in regions such as the province of Manitoba (Canada), where there is no screening programme in place, as (selective) ultrasound programmes in other countries have shown to decrease the rate of late presenting DDH. Improved access to health
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care and well baby clinics in rural areas, including clinical assessment of the hips beyond walking age, can improve diagnosis and overall outcome. It is unclear from our study if the late DDH is due to family predisposition and inbreeding or mechanically induced due to swaddling/restricted hip movements, a regional custom. Screening should also take into consideration risk factors for the province such as first female, breech and presence of clubfoot deformity. The latter is somewhat controversial, and could again be a regional entity, as current screening programmes no longer include clubfoot as a risk factor.(18,19) On the other hand, ultrasound has also its limitations in identifying relevant DDH. Despite abnormal findings on ultrasound suggestive for DDH within the first 6 months of life, many of these abnormalities will improve over time without treatment. Furthermore, abduction treatment of stable well-centered hips in 3 to 4 months old will not alter acetabular development, as 80% will become normal without treatment. Again, this questions the specificity of US as diagnostic tool to identify true hip disease based on Graf Classification alone. The role of Pavlik harness treatment over 6 months of age is questionable but can still be successful in 60% of the cases in moderate dislocation (≤ Graf type III). Prolongation of the Pavlik harness beyond 6 weeks of treatment did not alter the success rate. After failed Pavlik harness, medial approach lead to poor results in 20% of the patients for both radiographic and functional outcomes. The medial approach in patients younger than 6 months showed better results. Thus, the medial approach should probably be reserved to this age group. AVN rate was high, with almost 1/2 showing some changes during growth but eventually only 1/6 developed more severe proximal growth disturbance. The patient's observed outcome was not linked to the type of AVN but the severity of residual dysplasia. Finally, shape varian978-94-6419-087-8ts of AVN hips using SSM can identify early radiographic changes linked to poor outcome. This has the potential to develop as a tool for decision-making process at already a very young age and therefore improving the outcome.
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