INVESTIGATIONS OF THE EFFECT OF SHOCKWAVES ON THE STABILITY OF THE COMPOUND BETWEEN BONE AND POLYMETHYLMETHACRYLATE - AN INVITRO STUDY

The increasing number of revision surgery for failed total arthroplasty including the most difficult aspects of cement removal has lead to various developments of new instruments and techniques to facilitate this procedure. In this in vitro study the effect of extra-corporeal shockwaves on the bone-cement interface under this view was investigated. At first the pressure reduction of bounding shockwaves in their progress through compounds consisting of cortical bone-PMMA and cancellous bone-PMMA by means of a needle pressure probe was measured. In the second part of the experiments the mechanical and morphological effects of ESW on the PMMA-Bone-Interface of human femoral segments was tested. Using bone cement cadaveric femoral segments were implanted with stainless steel rods within the medullary canal and the PMMA-Bone-interface was treated with ESW. After treatment the segments were examined mechanically, radiologically and by microscopy. Between the treated and the control group no difference was found which could give any a reference to the disruption of the Cement-Bone-Interface caused by ESW. However, there were observations which indicated that ESW induces a increasing risk of intravasation of bone marrow. Considering these facts ESW seems not to be a good clinical adjunct in revision surgery.