PEEK or polyetheretherketone is a high performance, engineered plastic. It is one of the materials of choice for spinal implants as well as trauma fixation. Trauma fixation is the repair of broken bones or any bodily injury that can result from force or violence applied to the human body. It is also used for cardiovascular implants as well as in orthopedic surgery and dentistry. While in the past, metals such as titanium have often been used for these purposes, PEEK has taken the lead in many areas.
PEEK’s primary medical use has been in spinal implantation. PEEK has been used for many years in this application. Its safety and efficacy has been proven over many years. Patients with spinal stenosis, degenerative spondylolisthesis, degenerative disk disease, degenerative scoliosis and other diseases of the spine have experienced considerable relief by the implantation of PEEK spinal cages or spacers.
The optimal modulus of PEEK closely matches that of cortical bone which is the shaft of a bone that surrounds the marrow cavity. PEEK’s optimal modulus ensures the implant bears weight like a natural bone thereby reducing the likelihood of the nearby bone suffering density loss. The optimal modulus also helps prevent subsidence which is the sinking or settling in a bone for example in a prosthetic component of a total joint implant.
PEEK also has radiolucency which is the capability of a substance to allow a large amount of x-rays to pass through it, thus producing darkened images on x-ray films. Radiolucency permits a surgeon to better monitor the healing progress following a surgical procedure.
Trauma Fixation: Internal and External
These devices are implanted into the body and are used to maintain the shape and bearing load of a broken bone. These devices include cannulated screws, intermedullary nails, hip screws as well as pins and bone plates. These fixation devices must be biologically inert. PEEK meets that requirement.
Also, hardware implanted in the body must provide excellent support for as long as the treatment requires. Hardware such as PEEK bone plates provide superior fatigue strength when compared to metals like stainless steel. The material offers optimum flexibility and stiffness so it does not get in the way of the body’s own healing process. And should the implants need to be taken out, unmodified PEEK implants can be removed more easily than those made of metal due to less bone on-growth. Here again the radiolucency of PEEK allows the surgeon to better tract a patients healing process. PEEK is also lighter than metals and allows patients to move their joints and limbs more easily.
External fixation devices are some of the oldest medical devices known. Hippocrates described external fixation methods used to treat a tibia fracture. External fixation devices pierce the dermis and using components such as bolts and wires are secured to the underlying bone. This procedure is indicated when open fractures are present or if the injury must be temporarily stabilized prior to surgery.
PEEK plays an important role in cardiovascular surgeries. Less Invasive Ventricular Enhancement or LIVE is a procedure used to correct the heart after a myocardial infarction. It is often preferable to another procedure known as Surgical Ventricular Restoration or SVR. The heart must be stopped during an SVR and the surgeon must also make several very precise incisions. In a LIVE procedure the heart does not need to be stopped. Two anchors are positioned over the left ventricle and are tied together with a PEEK tether. This stabilizes the ventricle and allows the heart to function.
PEEK works well in orthopedic applications like knee and hip arthroplasty for many of the same reasons it is used in trauma fixation. PEEK has an optimal modulus similar to bone so the joint will bear weight and move like bone. As mentioned above PEEK is radiolucent. And PEEK is lighter in weight than metals so patients can move more easily.
PEEK has long been established in the field of dentistry. Most often it is used to make partial dentures. The material’s excellent abrasion and compressive resistance can handle chewing and tearing motions well. PEEK dental implants don’t affect taste. Patients report that the implants are comfortable and are not likely to cause allergic reactions or sores. Additionally, PEEK implants can be made to look like natural teeth.