The value of sonography after total replacement of the hip joint.

The value of ultrasonographic imaging after total hip arthroplasty (THA) ha s not been described in the literature so far. Aim: The typical postoperati ve sonographical findings are to be presented thus creating a basis for det ecting pathological alterations. Method: 73 consecutive patients after THA were sonographically and clinically examined at the beginning and the end o f the clinical rehabilitation phase. Laboratory tests detecting signs of in flammation and coagulation disorders were also performed. Results: In the e arly postoperative phase collection of liquid and its delayed resorption ar e the most important findings. The haematoma of the joint is usually organi sed within three weeks after the operation. It could be visualised in all p atients as a region of homogenous, slightly echogenic appearance - not clea rly distinguishable from the surrounding tissue and not compressible. Areas of low echogenicity were rarely seen. The forming of a neo-capsule could b e detected from the ninth postoperative week onwards. Peri-articular ossifi cation was not seen in this study. A loosening of prosthetic material did n ot occur. In the area of surgical approach irregularly shaped slightly echo genic and hardly compressible zones representing large haematomas could be found, The volume of these lesions could not be measured exactly due to the ir highly irregular shape. We did not observe large areas of seroma or liqu id haematoma interfering with the rehabilitation process. Conclusion: Exper ienced examiners are capable of demonstrating the sonographic features repr esenting signs of the healing process. Thus pathological developments can b e detected and adequate therapeutic measures be taken. Future studies will have to show to which degree ultrasonography can become relevant in the dia gnosis of endoprosthetic loosening.