STUDIES ON BONE CEMENTAS BIOMATERLALS

1997 Fiscal Year Final Research Report Summary

• Project/Area Number: 07045046
• Research Category: Grant-in-Aid for international Scientific Research
• Allocation Type: Single-year Grants
• Section: University-to-University Cooperative Research
• Research Field: Biomedical engineering/Biological material science
• Research Institution: TOKYO MEDICAL AND DENTAL UNIVERSITY
• Principal Investigator: IMAI Yohji TOKYO MED.DENT.UNIV., INST.MED.DENT.ENG., PROF., 医用器材研究所, 教授 (50013975)
• Co-Investigator(Kenkyū-buntansha): GRANT Mary UNIV.STRATHCLYDE,BIOENGINEERING UNIT,LECTURER, バイオエンジニアリングユニット, 講師 ; COURTNEY James UNIV.STRATHCLYDE,BIOENGINEERING UNIT,PROF., バイオエンジニアリングユニット, 教授 ; BARBENEL Joseph UNIV.STRATHCLYDE,BIOENGINEERING UNIT,PROF., バイオエンジニアリングユニット, 教授 ; TAKAKUDA Kazuo TOKYO MED.DENT.UNIV., INST.MED.DENT.ENG., ASSOC.PROF., 医用器材研究所, 助教授 (70108223) ; MIYAIRI Hiroo TOKYO MED.DENT.UNIV., INST.MED.DENT.ENG., PROF., 医用器材研究所, 教授 (50013892)
• Project Period (FY): 1995 – 1997
• Keywords: BONE CEMENT / METHYLMETHACTYLATE / MMA / RESIDUALMONOMER

Research Abstract

The main purposes of the studies were to investigate various aspects of residual monomer which affects biocompatibility and performance of methyl methacrylate (MMA) -based bone cements. Fourteen bone cement samples retrieved from patients at 3.3-14 years after hip replacement were characterized for residual MMA monomer in the cements, molecular waight, and glass transition temperature by high performance liquid chromatography, size exclusion chromatography and differential scanning calorimetry. About 5 % MMA remaining in bone cement just after curing at the time of operation was eluted gradually to the body. The residual MMA in ten samples was in the range between 0.1% and 1.4%, while little MMA was detected in 4 samples. Little correlation was noticed between the amount of residual monomer and the implantation time. The residual monomer was greater in the thick portion of the cements than in the thin. The results of the measurements of molecular waight and glass transition temperature suggested that the residual monomer is strongly influenced by curing prosess during hip replacement operation. It was suspected that uneven distribution of residual monomer as well as volume shrinkage resulted from elution of MMA can be responsible for loosening of hip prostheses which is most common clinical problem after the operation using bone cements.
A commercial bone cement was modified by adding a fluoropolymer to reduce residual monomer and evaluated for biocompatibility by four cell culture tests. The modified cement had lower residual MMA but a little more toxic tha the original cement unmodified.