The use of bioabsorbable materials in orthopaedics

Abstract

Bioabsorbable materials manufactured into fracture fixation devices dissolve slowly in the physiological environment, allowing gradual transfer of stresses to the healing tissue. This removes the need for implant removal surgery and reduces the risks of long term complications seen with bioinert materials, such as: stress shielding, migration, late infection and interference with imaging. When choosing a bioabsorbable material it is important to consider its mechanical properties and its biocompatibility. The three main categories of bioabsorbable materials available for use in trauma and orthopaedic surgery are: polymers, metals and ceramics. Bioabsorbable polymers are well established, with a number of commercially available orthopaedic devices including screws, bone anchors, sutures and drug delivery system. Polymers are limited in their capacity for use as bone fixation devices due to their weaker mechanical properties. Metals more closely align to the mechanical properties of bone. Bioabsorbable metal screws are commercially available but have unpredictable degradation profiles and are still largely in the early stages of development. To date, there have only been a few limited case series reporting their outcomes. Bioabsorbable ceramics have been used successfully as implant coatings and drug delivery systems. Their use in load bearing is limited by their brittle nature. The aim of this article is to provide an overview of the material science of bioabsorbable materials and to summarize their advantages, disadvantages, current clinical uses and potential future applications in orthopaedic surgery.