Lewis Gladius, Janna Si
Department of Mechanical Engineering, The University of Memphis, Memphis, Tennessee 38152, USA.
Clin Orthop Relat Res. 2006 Apr;445:233-8. doi: 10.1097/01.blo.0000201162.59819.28.
Bisphosphonates have the potential to reduce osteolysis, a phenomenon that has been postulated to play a key role in aseptic loosening of total joint replacements. Bisphosphonates may contribute to the in vivo longevity of total joint replacements. Some authors have suggested there are decreases in flexural strength and flexural modulus of the cured cement when a liquid form of disodium pamidronate is added to a commercially available acrylic bone cement (Palacos R). We proposed that it is comparatively easier to blend a bisphosphonate in powder form into an acrylic bone cement than it is when the drug is in liquid form; and that the cement's fatigue life is decreased when the bisphosphonate is added in liquid rather than in solid form. The bisphosphonate and bone cement used were alendronate sodium and Cemex XL, respectively. The fatigue tests were done using phosphate buffered saline solution at 37 degrees +/- 1 degrees C. The data supported both hypotheses. Our findings should guide orthopaedic surgeons when using bisphosphonate-impregnated acrylic bone cements in total joint replacements. Bisphosphonates are endogenous pyrophosphate analogs in which a carbon atom replaces the central oxygen atom. These therapeutic agents may be classified into nitrogen and non-nitrogen containing types. Some examples are alendronate, pamidronate, ibandronate, risedronate, etidronate, clodronate, and zoledronate. There are many targets and mechanisms of action of this family of drugs, therefore making them efficacious against diverse clinical conditions such as osteoporosis, periprosthetic bone loss subsequent to total joint replacement, tumor cell proliferation, apoptosis and angiogenesis, Charcot neuroarthropathy, rheumatoid arthritis, ankylosing spondylitis and spondyloarthropathies, and arterial calcification. It has been proposed that some bisphosphonates are effective against the mechanisms that have been suggested as being implicated in aseptic loosening of total joint replacements, these being osteoclast-mediated bone resorption and wear particle-induced osteolysis. A meta-analysis of randomized controlled trials showed that alendronate and pamidronate had beneficial effects maintaining periprosthetic bone for as much as 1 year after a total joint replacement.
双膦酸盐有降低骨溶解的潜力，骨溶解这一现象被认为在全关节置换的无菌性松动中起关键作用。双膦酸盐可能有助于全关节置换在体内的长期使用。一些作者指出，当将液体形式的帕米膦酸二钠添加到市售丙烯酸骨水泥（Palacos R）中时，固化水泥的弯曲强度和弯曲模量会降低。我们提出，将粉末形式的双膦酸盐混入丙烯酸骨水泥比将药物以液体形式混入相对更容易；并且当以液体而非固体形式添加双膦酸盐时，水泥的疲劳寿命会降低。所使用的双膦酸盐和骨水泥分别是阿仑膦酸钠和Cemex XL。疲劳试验在37摄氏度±1摄氏度的磷酸盐缓冲盐溶液中进行。数据支持了这两个假设。我们的研究结果应能为骨科医生在全关节置换中使用含双膦酸盐的丙烯酸骨水泥提供指导。双膦酸盐是内源性焦磷酸盐类似物，其中一个碳原子取代了中心氧原子。这些治疗剂可分为含氮和不含氮类型。一些例子包括阿仑膦酸、帕米膦酸、伊班膦酸、利塞膦酸、依替膦酸、氯膦酸和唑来膦酸。这类药物有许多作用靶点和作用机制，因此对多种临床病症有效，如骨质疏松症、全关节置换术后假体周围骨丢失、肿瘤细胞增殖、凋亡和血管生成、夏科氏神经关节病、类风湿性关节炎、强直性脊柱炎和脊柱关节病以及动脉钙化。有人提出，一些双膦酸盐对被认为与全关节置换无菌性松动有关的机制有效，这些机制是破骨细胞介导的骨吸收和磨损颗粒诱导的骨溶解。一项随机对照试验的荟萃分析表明，阿仑膦酸和帕米膦酸在全关节置换后长达1年的时间里对维持假体周围骨有有益作用。
