Bone Plates and Nails Implant Failure

Case Study 1 – Bone Plates and Nails Implant Failure

Introduction to Bones

There are basically two main types of bones in our body, they are the cortical and trabecular bones. Cortical bones which are often referred as compact bones are dense with a porosity range of from 5% to 10%. Cortical bones are mainly found in the shafts of long bones such as the tibia. It forms the outer shell of the trabecular bone at the ends of joints and the vertebrae.

Trabecular bones which are also known as cancellous or spongy bones are not as dense as compact bones with a porosity range from 50% and 90%. They are mainly found at the ends of long bones, in vertebrae, and in flat bones.

The bone tissues in our body have the ability to regenerate themselves. For instance, if a fractured bone is held together it can regenerate the tissue and regain most of its original strength.

For severe fractures, bone plates are surgically implanted to hold the bone in place.

In the process of bone plates designing, there are three main factors which must be look into. There are the designs, material selection and biocompatibility. Ideally bone plates should be strong enough to support the load placed on the fracture site as the bone heals. They should also have similar stiffness to that of the original bone. And also, the implant should be of non-toxic material and should not cause any inflammatory response in the body.

The stiffness of the implanted bone plate is a major consideration because the stress shielding will increase with the difference in stiffness. Stress shielding is the effect in which the implant will undertake most due to the load placed on the bone. Although it is best that the bone do not undertake too much of stress during the healing period, but it will reflect a bad sign when the bone fully recover and regains strength. If the bone was not allowed to carry an increasing load, there will be a reduction of bone mass and final regained strength.

In my report, I will be discussing two main types of bones material implants – plates and nails.

Plating

1. Metals

Iron and steel were the two materials which were very widely used in the 1920s. There are several factors to which result in their popularity. They dissolved rapidly and provoked erosion of adjacent bones. And their strong tensile strength made them especially attractive. But, stainless steels are rather inferior to other kind of better alloys in lieu to its biocompatibility and fatigue life. However, it still have it is still useful to patients to whom