A landmark research study from the International Hip Dysplasia Institute was published this month in the prestigious Journal of Bone and Joint Surgery [https://www.ncbi.nlm.nih.gov/pubmed/27440570]. The entire group of IHDI researchers participated in a study evaluating Pavlik harness treatment of infants younger than six months who had a completely dislocated hip. This is the largest study to date of infants with completely dislocated hips.
Some of the results were not too surprising but the quality of the data helps settle some old controversies, and there were some new findings. One finding was that even in the hands of these experts, the success rate with the Pavlik harness was only 79%. Previous studies may have reported better success rates, but those studies often included patients where the hip was only partly out of the socket or had mild instability. This IHDI study documented the dislocation with imaging prior to treatment while many previous studies have used the physician’s examination without confirming the dislocation by imaging.
The good news is that four out of five dislocated hips can be reduced by the Pavlik harness. However, the bad news is that almost one in five dislocated hips cannot be reduced with the Pavlik harness. The IHDI has started some new research attempting to discover why the Pavlik harness fails in some patients and what can be done to improve the results.
Some of the factors associated with failure were identified. When treatment began after age seven weeks, the success rate was only 65%. Also, there was a surprising difference in success for left hips – 85% success – compared to right hips – 64% success. Babies with stiff hip dislocations that couldn’t be reduced easily during the examination were unsuccessful with Pavlik harness treatment almost half the time – 45% failure. Some centers treated more patients than other centers but the lower volume centers had similar results to the higher volume centers. However, it is important to note that each center in this study was selected because they treat a lot of babies with DDH, so there weren’t any really low volume centers. The overall rate of avascular necrosis (AVN) was 5% but this number included even minor forms of necrosis. AVN occurs when blood circulation to the hip is disrupted because of treatment. This can have long term consequences on the growth and shape of the hip but minor amounts may resolve.
There were many more findings from this study and it continues to provide a rich source for detailed analysis of factors associated with brace success and brace failure. Each research site continues to gather specific information before, during and after treatment for each patient. This massive amount of data is entered into a database and managed at the University of Vancouver for privacy and for analysis. Such a study would have been impossible without support from the International Hip Dysplasia Institute and before modern methods of electronic communication.
This study has established a new standard for cooperative research into DDH. This has opened the door for much more detailed analysis as the study grows and patients are followed for longer. The IHDI is committed to continuing this research in a collaborative effort and we are dedicated to finding better solutions for treating DDH.