Efficacy of Bone Source~(TM) and Cementek~(TM) in comparison with Endobon~(TM) in critical size metaphyseal defects, using a minipig model

摘要

Introduction: To examine and compare biocompatibility, osteocompatibility, rate of resorption, and remodelling dynamics of 2 calcium phosphate cements in comparison with a well-established hydroxyapatite ceramic. Materials and methods: In a randomised fashion, Bone Source~(TM), Cementek~(TM), and Endobon~(TM) were implanted bilaterally into the proximal metaphyseal tibiae of 35 Gottinger minipigs in a direct right vs. left intra-individual comparison. Fluorescent labelling was used. Histological and morphometric evaluations were carried out at 6, 12, and 52 weeks. Results: All bone substitutes showed good biocompatibility, bioactivity, and osteoconductivity. Endobon~( TM) was not degraded over the follow-up period. Cementek~(TM) was degraded constantly and significantly over the time intervals, whereas Bone Source~(TM) was degraded mainly from the 6 week to 12 week interval. After 52 weeks, a significant difference of residual material within the defect zone was detected between all substitutes, with the highest resorption rate for Cementek~(TM). Bone Source~(TM) was least degraded. Defects filled with Endobon~(TM) were characterised by a significantly continuous bony ingrowth over the time intervals. Bone formation within the defects filled with Cementek~(TM) and Bone Source~(TM) showed significant peaks 12 weeks after implantation. After 52 weeks, a significant difference in the amount of new bone within the defect area was detected, with the highest levels for Endobon~(TM), followed by Cementek~(TM). Conclusion: After 1 year a restitutio ad integrum could not be observed in any treatment group. The ceramic Endobon~(TM) showed the expected response histologically. Based on its porosity it excelled in osteoconductivity. Concerning the calcium phosphate cements, a thorough osseous incorporation seemed to inhibit further degradation of both bone substitute materials.