Abstract:Objective To observe the biomechanical changes of subchondral bone in the early stage of knee joint instability and effect of diphosphonate therapy so as to investigate the role of the early biomechanical changes of subchondral bone in the onset and development of osteoarthritis (OA). Methods Sixty healthy male New Zealand white rabbits were assigned to model group (n=24), diphosphonate group (n=24) and control group (n=12) according to random number table. Joint destabilization by anterior cruciate ligament transection of the right knee of the rabbits was performed to induce OA models. Rabbits in diphosphonate group received subcutaneous injection of 0.01 mg/kg diphosphonate (risedronate) per day, and isotonic saline solution of the same volume was subcutaneously given to rabbits in model and control groups. Half the animals in each group were killed by aeroembolism at postoperative 4 weeks and 12 weeks respectively. Surgical knee joint with preservation of each 2 cm bone above and below joint surface was dissected to perform gross scoring. Thereafter, two-dimensional image profile was achieved by Micro-CT examination and converted into Ansys for limit element analysis after fitting in Mimics software. Results At four weeks, bone volume fraction (BVF), elastic modulus (EM), reaction force (RF), and mean Von Mises stress were all declined in three groups, the lowest level in the model group (P<0.01). The diphosphonate group also had lower levels than the control group, with insignificant difference. Bone mineral density (BMD) in the model group was obviously declined in contrast with the diphosphonate and control groups (P<0.01), but there were no significant difference between the diphosphonate group and the control group. At 12 weeks, the model group showed higher level of BVF and BMD, but lower level of EM, RF and Von Mises stress in comparison with the control and diphosphonate groups (P<0.01). EM, RF, and Von Mises stress were lower in the diphosphonate group than those in the control group as well, but the difference was statistically insignificant. The model group showed that BVF, BMD, EM, RF, and Von Mises stress at 12 weeks were improved from those at 4 weeks (P<0.01). Conclusions Biomechanical properties of subchondral bone are affected in the early stage of knee joint instability and a notable decrease of EM is observed in the early stage, followed by an enhancement in late stage. It means that the biomechanical changes of subchondral bone in the early stage of knee joint instability may be connected with the bone resorption resulting from abnormal stress. On the contrary, diphosphonate may markedly improve EM of subchondral bone through inhibiting bone resorption.
CHEN Hai-nan,DONG Qi-rong,JIANG Wei et al. Finite element analysis of biomechanical variation of subchondral bone in osteoarthritis and effect of diphosphonate therapy[J]. CHINESE JOURNAL OF TRAUMA, 2013, 29(6): 550-555.
[1]Anderson-MacKenzie JM, Quasnichka HL, Starr RL, et al. Fundamental subchondral bone changes in spontaneous knee osteoarthritis. Int J Biochem Cell Biol, 2005, 37(1):224-236.
[2]Blaney Davidson EN, van der Kraan PM, van den Berg WB. TGF-beta and osteoarthritis.Osteoarthritis Cartilage, 2007, 15(6):597-604.
[3]Sakao K, Takahashi KA, Arai Y, et al. Asporin and transforming growth factor-beta gene expression in osteoblasts from subchondral bone and osteophytes in osteoarthritis. J Orthop Sci, 2009, 14(6):738-747.
[4]Kwan Tat S, Amiable N, Pelletier JP, et al. Modulation of OPG, RANK and RANKL by human chondrocytes and their implication during osteoarthritis.Rheumatology (Oxford), 2009, 48(12):1482-1490.
[5]Ahmed S, Silverman MD, Marotte H, et al. Down-regulation of myeloid cell leukemia 1 by epigallocatechin-3-gallate sensitizes rheumatoid arthritis synovial fibroblasts to tumor necrosis factor alpha-induced apoptosis. Arthritis Rheum, 2009, 60(5):1282-1293.
[6]Homminga J, Huiskes R, Van Rietbergen B, et al. Introduction and evaluation of a gray-value voxel conversion technique. J Biomech, 2001, 34(4):513-517.
[7]Macneil JA, Boyd SK. Bone strength at the distal radius can be estimated from high-resolution peripheral quantitative computed tomography and the finite element method. Bone, 2008, 42(6):1203-1213.
[8]Schencking M, Wilm S, Redaelli M. A comparison of Kneipp hydrotherapy with conventional physiotherapy in the treatment of osteoarthritis: a pilot trial. J Integr Med, 2013, 11(1):17-25.
[9]Teo JC, Si-Hoe KM, Keh JE, et al. Relationship between CT intensity, micro-architecture and mechanical properties of porcine vertebral cancellous bone. Clin Biomech, 2006, 21(3):235-244.
[10]McKinley TO, Borrelli J Jr, D’Lima DD, et al. Basic science of intra-articular fractures and posttraumatic osteoarthritis. J Orthop Trauma, 2010, 24(9):567-570.
[12]Xia ZH, Zhou CW, Yong QL, et al. On selection of repeated unit cell model and application of unified periodic boundary conditions in micro-mechanical analysis of composites. Int J Solids Struct, 2006, 43(2):266-278.
[13]Fazzalari NL, Kuliwaba JS, Forwood MR. Cancellous bone microdamage in the proximal femur: influence of age and osteoarthritis on damage morphology and regional distribution. Bone, 2002, 31(6):697-702.
[14]Radin EL, Rose RM. Role of subchondra1 bone in the initiation and progression of cartilage damage. Clin Orthop Relat Res, 1986, (213):34-40.