Effect of ibandronate on bending strength and toughness of rodent cortical bone

Abstract

ObjectivesThere remains conflicting evidence regarding cortical bone strength following bisphosphonate therapy. As part of a study to assess the effects of bisphosphonate treatment on the healing of rat tibial fractures, the mechanical properties and radiological density of the uninjured contralateral tibia was assessed.MethodsSkeletally mature aged rats were used. A total of 14 rats received 1µg/kg ibandronate (iban) daily and 17 rats received 1 ml 0.9% sodium chloride (control) daily. Stress at failure and toughness of the tibial diaphysis were calculated following four-point bending tests.ResultsUninjured cortical bone in the iban group had a significantly greater mean (standard deviation (sd)), p < 0.001, stress at failure of 219.2 MPa (sd 45.99) compared with the control group (169.46 MPa (sd 43.32)) following only nine weeks of therapy. Despite this, the cortical bone toughness and work to failure was similar. There was no significant difference in radiological density or physical dimensions of the cortical bone.ConclusionsIban therapy increases the stress at failure of uninjured cortical bone. This has relevance when normalising the strength of repair in a limb when comparing it with the unfractured limb. However, the 20% increase in stress at failure with iban therapy needs to be interpreted with caution as there was no corresponding increase in toughness or work to failure. Further research is required in this area, especially with the increasing clinical burden of low-energy diaphyseal femoral fractures following prolonged use of bisphosphonates.Cite this article: Bone Joint Res 2015;4:99–104

Biomechanical and tomographic differences in the microarchitecture and strength of trabecular and cortical bone in the early stage of male osteoporosis

“…Our present findings are similar to the work of Blouin et al who described how at 1 month after an orchietomy, the architecture of cortical bone in aged male Wistar rats had not changed [42]. Vandenput et al showed a considerable difference in the volume of cortical bone 4 months after orchiectomy in aged male Wistar Hannover rats [45]. Another study also revealed that long term (> 4 months) after orchiectomy, the cortical bone mass was significantly affected [46].…”

Biomechanical Properties of Metastatically Involved Osteolytic Bone

“…Mechanical and material properties of healthy and metastatically involved bone have also been assessed for treatments such as bisphosphonates [122][123][124][125][126][127], chemotherapeutics [128][129][130][131], photodynamic therapy (PDT) [85,132], Rank-L inhibitors [133][134][135][136], and multimodal treatment combinations [137,138]. Bisphosphonates and Rank-L inhibitors slow down bone turnover, leading to increased bone mineralization and slower osteolytic tumour growth.…”