Use of strontium-enriched bioactive bone cement in enhancing tendon osteointegration in a rabbit anterior cruciate ligament reconstruction model

Abstract

Introduction: It was hypothesised that strontium led to accelerated healing of strontium-enriched calcium phosphate cement (Sr-CPC)–treated soft tissue tendon graft within the bone tunnel in anterior cruciate ligament (ACL) reconstruction. This hypothesis was tested in a rabbit ACL reconstruction model using Achilles tendon allograft. Methods: A total of 30 bilateral ACL reconstructions were performed in 15 rabbits. The graft on the tested limb was treated with Sr-CPC, while that on the contralateral limb was treated with CPC. Three were sacrificed for histomorphometric analysis respectively at 3, 6, 9, 12, and 24 weeks after the index operation. Histomorphometric analysis of the healing of graft was done by 2 independent observers in 42 histological zones per animal using a scoring system of 0 to 9. The data were analysed by Mann-Whitney U test. Results: Accelerated healing of the graft within bone tunnel was noted in the strontium-treated limb at 3, 6, 9, and 12 weeks after the operation (p < 0.001) when compared with the CPC-treated limb. Complete healing of the graft by Sharpey’s fibre formation at 9 weeks and early evidence of remodelling into normal ACL insertion site at 12 weeks were noted in the SrCPC group. The healing of the graft in the CPC-treated limb was noted 3 to 6 weeks slower than the Sr-CPC group. Conclusion: Strontium is the main contributing factor leading to accelerated healing of Sr-CPC–treated soft tissue tendon graft in a rabbit ACL reconstruction model.