Question

how do we test orthopedic materials? please one page long not half page long essay.

Answer 1

Determining biocompatibility of material intended for medical application is an important aspect of orthopedic research. As per International Standard Organization (ISO 10993-1. Guidance on selection of tests) it is mandatory to conduct both in vitro and in vivo tests for a complete assessment of biocompatibility. Any investigating orthopaedic biomaterials, undergoes through a set of in vitro and in vivo tests to determine its biocompatibility, osteogenetic and osteointegration properties.   For example, when a material is intended for clinical use in bone, in vitro and in vivo tests are required depending on the length of time that the device is in contact with the human body.

Regulatory agency – FDA in 1994 has released a guidance document for the industries involved in developing orthopaedic materials. As per guidance document for testing orthopaedic implants with modified metallic surfaces apposing bone or bone cement below information is suggested to provide by the manufacturer

1. Metallurgical analysis of the materials
2. Microstructure of the modified surface
3. Physical properties
4. Mechanical properties
5. Biocompatibility
6. Clinical data

There are various pre-clinical models (in vitro and in vivo) are available to determine the biocompatibility of material and implant success.

1. In vitro models

In vitro tests are designed using osteosarcoma and immortalized cell lines to determine the toxicity of biomaterial prior to the in vivo implantation studies. These cell based test provide biochemical and molecular information regarding biomaterial compatibility. However, due to the malignant origin of these cell lines, the findings obtained should be evaluated with great caution. Primary osteoblasts directly cultured from small fragments of human and animal is the preferred cell model. These in vitro test are reliable, reproducible and cost effective. A wide range of biomaterial can be tested in a shorter span of time. With the advancement of technology and usage of human primary cells in vitro models could be a good alternate for animal models.

2. In vivo animal models

Animal studies are the bridge between in vitro studies and clinical trials. Animal models are useful in performing chronic and long term investigations in determining the bio functionality and effectiveness of product along with the biomaterial under investigation. Depending on the purpose of implant, biomaterial are implanted on long bones to investigate histological, histomorphometric and biomechanical properties on biomaterial. The majority of bone implants are studied in vivo follow the International Standard Organization regulations (ISO 10993-6. Tests for local effects after implantation).