[Redefinition of the proximal perichondrium and perichondrial gap in hip ultrasound imaging]

As a result of the improvement in the resolution of diagnostic sonography equipment it is possible to depict sonographic echoes of structures in the area of the preformed cartilage acetabular roof, especially in the region of the proximal perichondrium, perichondrial gap and the joint capsule that up to now have not been anatomically identified. Therefore, the question arises as to which anatomical structures these newly observed sonographic echoes can be classed with. Hip-joint NMR images of corpses were made and compared to anatomical specimen, anatomical sections and sonograms of high-resolution ultrasound equipment. Through this comparative study it was possible to demonstrate that the echo of the proximal perichondrium is anatomically consistent with the proximal perichondrium itself, parts of the joint capsule and the insertion of the musculus rectus femoris tendon. Identification of the ligamentum ischiofemorale and its separation from the labrum acetabulare, the joint capsule and the musculus rectus femoris tendon leads to better interpretation of the perichondrial gap in the sonogram. Common terms, such as "proximal perichondrium" and "perichondrial gap" obtain a new anatomical assessment. These terms, taken as a basis for knowledge of the anatomical structures, can be used as usual. There are no consequences for hip sonography today if the definition of the distinction between type III and type IV, and of the standard section is used further as the basis of sonography even if these terms have received a new anatomical classification.