Correspondence (reply): In Reply

Our review article (1) aimed to provide readers with a practical algorithm to be applied in routine clinical practice. Because of the many possible causes of hip pain in children, we focused on the most common symptoms and the most relevant differential diagnoses. Since our article was written for a wide readership, some aspects were intentionally not discussed in depth and to the extent as would have been the case for a review article in one pathological entity. This is the only way in which to meet the requirements of a CME article.

Dr. Bouklas draws attention to the rare but painful retrotorsion of the hip as a possible but very rare differential diagnosis.

Dr. Dückers explains that the term “juvenile rheumatic coxitis” has been replaced by “juvenile idiopathic arthritis” [note: this refers to a phrase only found in the German-language version of the article]. With regard to diagnostic arthrocentesis, we restricted the recommendation obviously to those cases where using less invasive diagnostic tools did not yield any differentiation between a septic and aseptic pathogenesis. Further details can be seen in the revised JIA S2k guideline, which was not available at the time of our publication (2).

Prof. Heimkes criticized our intertwining of two entities—congenital hip dysplasia and neurogenic hip dislocation. This is partly the result of strict word limits. On the other hand, we wanted only to explain fundamental differences and show the different etiopathogeneses. We are aware that in congenital hip dysplasia, pain will develop only during adolescence, which is why in Table 1 we listed these under adolescence. It is always possible that an adolescent patient presents with hip pain, and only then is hip dysplasia diagnosed, although this was congenitally already present. Even though hip screening in the context of the U3 has been found in retrospective analyses to lead to a reduction in such cases, this differential diagnosis cannot and must not remain unmentioned.

Prof. Heimkes, Dr. Seidl, and Dr. Hien take clear position regarding the value of general hip ultrasound screening. We also carry out Graf hip screening and are aware of the clinical benefits of this investigation. Let me add that hip ultrasound is carried out generally in all infants only in Germany and Austria (the country of the inventor’s origin) and parts of Switzerland, whereas in almost all other countries in the world, hip ultrasound is carried out only in cases of an abnormal clinical finding (“general” versus “targeted”). Although the retrospective studies mentioned by our correspondents suggest that general hip ultrasound screening should be introduced, prospective studies that confirm a positive effect are still lacking (3). Relevant attempts to introduce general hip screening in Europe have failed, even though a pertinent consensus exists (4). An additional obstacle lies in the fact that a recent international literature review (5), which analyzed different hip types according to Graf (N=4876) while considering all grades of dysplasia and types displacement, showed in almost all cases a natural benign course without any interventions. The authors showed a spontaneous good outcome even for hip displacement: “For Graf 3 hips more than 50% were reported to develop into normal hips without treatment. As for Graf 4 hips this percentage was reported below 50%.” A Norwegian study in which hip ultrasounds screening was undertaken in addition to a clinical examination should also be understood on this background. The authors observed that the treatment rate doubled. But this did not lead to any reduction of the already lower number of subsequent symptomatic cases of hip dysplasia or those requiring treatment (6). Even though we—as experienced pediatric orthopedic surgeons and advocates of general hip ultrasound screening—do not agree with these comments, they are part of the state of knowledge internationally.

Our review article (1) aspired to explain the current state of international scientific knowledge to our readers. These, as treating doctors, are obliged—especially in the setting of pediatric patients—to inform patients/parents accordingly about the state of science and evidence. It is therefore all the more important to be able to access a sound knowledge base without putting personal attitude above (international) evidence.