TRAP 5b as an early predictor for implant loosening in a rat model

Introduction:

Aseptic loosening is the leading cause of implant failure. Aseptic loosening is the result of different mechanisms leading to increased periprosthetic bone resorption. Therefore, measuring biochemical bone markers can be an approach to identify early resorption and implant loosening We hypothesized that TRAP 5b is a sensitive marker for periprosthetic bone turnover and a possible predictor of aseptic loosening.

Methods:

A rat model of aseptic loosening with continuous infusion of polyethylene particles was used. Given the fact that many patients undergoing total joint replacement and developing aseptic loosening suffer from osteoporosis, the rats were ovariectomized 12 weeks before the experimental procedures to induce poor bone quality and include the influence of osteoporosis on the loosening process. 60 ovx rats were used and randomized into the different experimental groups. Blood samples were drawn 12, 6 and 1 weeks before the surgery and on Post Operative Day 0, 7, 14, 28, 35, and 42 The serum was analyzed by ELISA for Osteocalcin, PINP, CTX concentrations and TRAP 5b activity. To verify the result of ovariectomy, bone mineral density was measured by DEXA.

Results:

Results for TRAP 5b: Postoperatively, the maximum was reached on day 7 and TRAP 5b activity decreased slowly until day 42. Similar, in the sham group maximum was reached on day 7 and it decreased slowly until day 42. On every day, TRAP 5b activity in the prostheses group was significantly higher than TRAP 5b activity in the sham-operated group

Discussion:

Our investigation showed for TRAP 5b, a high activity levels as an indication for an increased periprosthetic bone resorption leading to aseptic loosening. TRAP 5b is eligible for the early diagnosis of aseptic loosening.