Wear products of metal implants are known to induce biological events which may have profound consequences for the microcirculation of skeletal muscle. Using the skinfold chamber model and intravital microscopy we assessed microcirculatory parameters in skeletal muscle after confrontation with titanium and stainless-steel wear debris, comparing the results with those of bulk materials.

Implantation of stainless-steel bulk and debris led to a distinct activation of leukocytes combined with a disruption of the microvascular endothelial integrity and massive leukocyte extravasation. While animals with bulk stainless steel showed a tendency to recuperation, stainless-steel wear debris induced such severe inflammation and massive oedema that the microcirculation broke down within 24 hours after implantation. Titanium bulk caused only a transient increase in leukocyte-endothelial cell interaction within the first 120 minutes and no significant change in macromolecular leakage, leukocyte extravasation or venular diameter. Titanium wear debris produced a markedly lower inflammatory reaction than stainless-steel bulk, indicating that a general benefit of bulk versus debris could not be claimed. Depending on its constituents, wear debris is capable of eliciting acute inflammation which may result in endothelial damage and subsequent failure of microperfusion. Our results indicate that not only the bulk properties of orthopaedic implants but also the microcirculatory implications of inevitable wear debris play a pivotal role in determining the biocompatibility of an implant.

Of 42 patients with resolvingscoliosis, 34 were followed up for more than 25 infantile idiopathicyears. Twenty had been primarily treated in a plaster bed and 14 by physiotherapy. The mean angle of the curve at presentation was 17° and at follow-up it was 5°. No patient had significant progression of the scoliosis during the growth spurt. When adults few had back pain or an increased disability score and there was no interference with work or social activities. The rib-vertebra angle difference proved to be an essential radiological sign when distinguishing resolving from progressive infantile idiopathic scoliosis. There was no advantage of plaster over physiotherapy with regard to either the time to resolution or the functional outcome. Treatment of resolving infantile idiopathic scoliosis in a plaster bed is therefore now outdated.