Cheung Wing-Hoi, Leung Kwok-Sui, Chow Simon Kwoon-Ho
Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong; Orthopaedic Research Laboratory of Translational Medicine Research and Development Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, China.
Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong; Orthopaedic Research Laboratory of Translational Medicine Research and Development Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, China.
Injury. 2016 Jan;47 Suppl 1:S39-42. doi: 10.1016/S0020-1383(16)30010-9.
Osteoporotic fracture is known to have impaired healing capacity and therefore takes longer time to heal, as compared with younger one. The mechanism of impaired osteoporotic fracture healing is multifactorial, where lower responsiveness to mechanical loading is generally believed to be one factor, yet not absolutely confirmed. In recent years, low intensity pulsed ultrasound (LIPUS) is demonstrated to have good efficacy in treating normal fracture healing, as proven by many randomized controlled trials, as well as in vitro and animal evidences. The effects of LIPUS on osteoporotic fracture healing was also validated in an animal study, which revealed that osteoporotic fractured bone of SD rats showed radiologically and biomechanically comparable responses to LIPUS as age-matched normal fracture healing, in terms of callus width, bridging rate, bone volume fraction, and stiffness etc. Gene expression profiling also confirmed that osteoporotic fractured bone responded to LIPUS very well by upregulating Col1 and BMP2 (osteogenesis) at early phase, VEGF (angiogenesis) at middle phase and RANKL (remodeling) at late phase. These confirm that osteoporotic bones respond well to LIPUS as good as normal bone. These findings may be associated with estrogen receptors (ERs), as estrogen depletion is sensed and relayed by ERs and ERs also function as mechano-sensors. A previous study observed a delayed ERs expression pattern in fracture callus of OVX rats, as compared with SHAM rats, which correlated well with the expression pattern of BMP-2 (callus formation-related gene). Hence, the responses of osteoporotic fractured bone to LIPUS may be related to the local ERs expression at fracture callus that needs further experiments to validate.
众所周知，骨质疏松性骨折的愈合能力受损，因此与年轻患者的骨折相比，愈合时间更长。骨质疏松性骨折愈合受损的机制是多因素的，其中普遍认为对机械负荷的反应性较低是一个因素，但尚未得到绝对证实。近年来，许多随机对照试验以及体外和动物实验证据均证明，低强度脉冲超声（LIPUS）在治疗正常骨折愈合方面具有良好疗效。一项动物研究也验证了LIPUS对骨质疏松性骨折愈合的影响，该研究表明，就骨痂宽度、桥接率、骨体积分数和刚度等而言，SD大鼠的骨质疏松性骨折骨在放射学和生物力学上对LIPUS的反应与年龄匹配的正常骨折愈合相当。基因表达谱分析还证实，骨质疏松性骨折骨对LIPUS反应良好，在早期上调Col1和BMP2（成骨），中期上调VEGF（血管生成），后期上调RANKL（重塑）。这些证实骨质疏松性骨对LIPUS的反应与正常骨一样良好。这些发现可能与雌激素受体（ERs）有关，因为雌激素耗竭由ERs感知和传递，并且ERs还充当机械传感器。先前的一项研究观察到，与假手术大鼠相比，去卵巢大鼠骨折骨痂中ERs表达模式延迟，这与BMP-2（与骨痂形成相关的基因）的表达模式密切相关。因此，骨质疏松性骨折骨对LIPUS的反应可能与骨折骨痂处局部ERs表达有关，这需要进一步实验来验证。
