Madigan S, Towler M R, Lewis G
Materials and Surface Science Institute, University of Limerick, Limerick, Ireland.
J Mater Sci Mater Med. 2006 Apr;17(4):307-11. doi: 10.1007/s10856-006-8227-9.
In cemented arthroplasties, the two-part self-curing acrylic bone cement is currently the only material used for anchoring the total joint replacement to the contiguous bone. In virtually all commercially available formulations of this cement, the agents used for the initiation and activation/co-initiation of the radical polymerisation reaction are benzoyl peroxide (BPO) and N, N dimethyl-para-toluidine (DMPT), respectively. There are no reports in the open literature on the rationale for the amounts of these and other constituents in the formulations of the cement. Given the concerns that have been raised in the literature regarding the effect of residual DMPT on the body, it is important to keep the starting amounts of BPO and DMPT as high and as low, respectively, as possible. In the present work, the focus is on the relative amounts of these two agents in the case of one widely used commercial formulation, Surgical Simplex(R) P. Thirty variants of this cement were formulated, covering three concentrations of the co-polymer/BPO (75%, 80%, and 85% of the mass of the powder) and DMPT amounts (ranging from 0.8 %v/v to 2.4% v/v.) The setting time (t(set)), the peak temperature reached during the cement polymerisation process (T(max)), and the ultimate compressive strength (UCS) of each of the formulations were determined in accordance with procedures specified in ISO 5833. A critical examination of all the results indicated that the optimum ratio of the concentration of the initiator (BPO embedded in the PMMA-sytrene co-polymer) to that of the activator/co-initiator (DMPT) in Surgical Simplex(R) P is 57.14 (80%w/w co-polymer + BPO per 1.4%v/v DMPT). The mean values of t(set), T(max), and UCS of this optimum formulation were determined to be 12.30 min, 68 degrees C, and 101 MPa, respectively, all of which are within the limits specified in ISO 5833. The commercially available formulation of this cement contains 2.5%v/v DMPT, while the optimum formulation, as found in the present work, has 44% less DMPT, which may translate to a smaller amount of residual DMPT that is available for elution into the periprosthetic tissue in a cemented arthroplasty, over the in vivo life of the joint replacement.
在骨水泥型关节置换术中，双组分自固化丙烯酸骨水泥是目前唯一用于将全关节置换物固定至相邻骨骼的材料。在这种骨水泥几乎所有市售配方中，用于引发和激活/共引发自由基聚合反应的试剂分别是过氧化苯甲酰（BPO）和N，N - 二甲基对甲苯胺（DMPT）。公开文献中没有关于骨水泥配方中这些成分及其他成分用量依据的报道。鉴于文献中对残留DMPT对人体影响的担忧，尽可能分别将BPO和DMPT的起始用量保持在尽可能高和尽可能低的水平很重要。在本研究中，重点关注一种广泛使用的市售配方Surgical Simplex(R) P中这两种试剂的相对用量。配制了该骨水泥的30种变体，涵盖三种共聚物/BPO浓度（占粉末质量的75%、80%和85%）以及DMPT用量范围（0.8 %v/v至2.4% v/v）。根据ISO 5833规定的程序测定每种配方的凝固时间（t(set)）、骨水泥聚合过程中达到的峰值温度（T(max)）和极限抗压强度（UCS）。对所有结果的严格审查表明，Surgical Simplex(R) P中引发剂（嵌入聚甲基丙烯酸甲酯 - 苯乙烯共聚物中的BPO）与激活剂/共引发剂（DMPT）浓度的最佳比例为57.14（每1.4%v/v DMPT含80%w/w共聚物 + BPO）。该最佳配方的t(set)、T(max)和UCS的平均值分别确定为12.30分钟、68摄氏度和101兆帕，所有这些均在ISO 5833规定的范围内。这种骨水泥的市售配方含有2.5%v/v DMPT，而本研究中发现的最佳配方DMPT含量少44%，这可能意味着在关节置换物的体内使用寿命期间，在骨水泥型关节置换术中可洗脱到假体周围组织中的残留DMPT量会更少。
