The value of sonography after total replacement of the knee joint - A prospective study

Purpose: Ultrasound is often applied in the course of treatment after knee arthroplasty, although sonographic normal findings have not been described so far. Characterising these and comparing them to clinical disorders was t he purpose of this study. Intra- and extra-articular hematoma and the imagi ng of the traumatised extension apparatus of the knee joint were of special interest. Methods: During 4 weeks all consecutive patients after knee arth roplasty were examined clinically and sonographically. Furthermore, the blo od parameters were controlled for signs of inflammation or coagulation diso rders. These findings were then re-checked before the end of hospital rehab ilitation treatment. Results: In all of the patients, ultrasound revealed i ntra-articular fluid at the beginning and at the end of hospital treatment. The fluid area, differing in extension, was markedly reduced or showed les s echogenicity concomitant with an organisation. The patellar tendon in all of the patients showed a loss of echogenicity at the site of operative inc ision, mostly at the patellar insertion, and a thickening extending through out the middle part of the tendon even at control. Dynamic ultrasound exami nation displayed one case of a major defect which had to be revised. Blood parameters of inflammation were decreased, coagulation parameters were norm al. Conclusion: After knee arthoplasty, extended intra-articular knee hemat omas are not rare, only being resorbed or organised to a small degree durin g a rehabilitation period of three weeks, therefore not yielding relevant i nformation for the course of treatment. Clinical Relevance: The patellar li gaments show alterations comparable to acute tendopathy, thus not recommend ing use of maximal forces or too high stretching of the tendon tissue. Soft tissue defects with the need for interruption of the rehabilitation progra mme may be detected sonographically. Further studies will be necessary to e xplore the course of restructuring. Disorders of patellar sliding movement and signs of prosthetic loosening cannot be sufficiently judged at the pres ent time.