Bakterielle Kolonisation von teleskopierbaren Titanimplantaten (VEPTR-System) bei Kindern und Jugendlichen mit Wirbelsäulendeformitäten

This dissertation deals with bacterial colonisation of the Vertical-expandable-prosthetic-titanium-rib (VEPTR) system for the treatment of children and adolescents with spinal deformities. Possible influencing factors for the risk of germination were analysed and suitable examination methods were investigated. The underlying study comprised 42 children and adolescents who were treated with a telescopic titanium implant (VEPTR system) due to scoliotic deformity of the vertebral column. These patients underwent surgical treatment routinely at six-month intervals. Biometric, clinical, laboratory-chemical, microbiological and microscopic data were collected. For the microbiological and microscopic diagnostics, parts of the telescope system which are routinely taken out during the extension operation were used together with swabs and tissue samples. On the basis of all examination procedures, patients were classified as positive, when bacterial colonisation was confirmed, or as negative, when no evidence for bacterial colonisation was found. A more precise differentiation was made between positive patients with a positive result in at least one examination procedure and certainly positive patients with a pathological result in two or more examination procedures. The certainly positive patients were a subgroup of the group of all positive patients. This approach resulted in a bacterial colonisation rate of 36% (n=15) positive patients, with 14% (n=6) certainly positive patients. Possible influencing factors for bacterial colonisation were correlated in comparison between the positive (n=15) and the negative (n=27) patients. No significant differences were observed in terms of sex, body size, body weight, primary disease, concomitant disease, number of preoperations, type of VEPTR system (VEPTR I/II) and previous mechanical or infectious complications in the implant area. However, the positive patients were significantly older than the negative patients. The clinical observation and the performed blood tests showed no difference between both groups. The various diagnostic methods had different detection rates for bacterial colonisation. The swab with tissue revealed the most positive results with 73% (n=11) of all patients, who were later classified as positive, being detected. Other methods, particularly the polymerase chain reaction, showed only a low detection rate of 7%. Consistent with previous reports, propionibacteria (47%) and coagulase-negative staphylococci (40%) were predominantly found in the samples of positive patients. The bacterial colonisation with propionibacteria was associated with acne in the back region in the majority of cases. Therefore, a thorough laviation of the patients prior to the operation could possibly prevent bacterial colonisation of implants. A study confirming this hypothesis has been initiated recently. This study showed significantly higher probabilities of bacterial colonisation of titanium implants in children than initially assumed. As a therapeutic consequence of this study, the procedure has been changed in the department for pediatric orthopaedics in Gottingen. As an innovation a two-step procedure is implemented: instead of changing the VEPTR system into a permanent implant in one operation, two operations with a period without any external material and a long-term treatment with antibiotics are necessary. This could prevent a bacterial colonisation of the final implant system inserted during spondylodesis. With an individual patient-oriented procedure, increased therapeutic safety could be achieved.