The main goal of skull repair is to repair the damaged area of the skull of each patient, and the commonly used materials are PEEK and titanium mesh.

 

3D Printed Prosthesis: Selection of Cranial Repair Materials

 

Skull defect repair surgery, also known as cranioplasty, is a common procedure that is usually used for patients who need to undergo decompression surgery due to increased intracranial pressure due to head trauma, intracranial tumors, cerebrovascular accidents, etc. The goal of surgery is to fill and repair the defected skull with different restorative materials to achieve the goal of treatment. The neurosurgery department of many hospitals is now able to perform this procedure.

 

Normally, the skull supports the cranial cavity and helps maintain the physiological balance of intracranial pressure. However, after surgery, the missing skull is unable to provide support, and atmospheric pressure increases the intracranial effect, which may cause the brain tissue to shift when the body position changes. In the early postoperative period, although cerebral perfusion pressure and cerebral blood flow may increase transiently on the decompression side, as the support of the flap weakens, the atmospheric pressure gradually increases, which may lead to cerebrospinal fluid circulatory dynamics and decreased cerebral perfusion pressure, resulting in flap reveagation syndrome, which may include the most common motor weakness, followed by cognitive deficits, language impairment, altered levels of consciousness, headaches, seizures or EEG changes, and even cranial nerve dysfunction. There have also been reports of psychological disorders in patients with skull defects.

 

The main goal of skull repair is to repair the damaged area of the skull of each patient, so that the patient can obtain health, protect brain tissue, improve cranial nerve function and restore the appearance of the head.

 

Medical titanium mesh

Medical titanium alloys have been widely used in the medical field, especially in skull repair, due to their excellent biocompatibility and high mechanical strength. As early as 1964, titanium alloys were first used in skull repair surgery. Titanium mesh has the characteristics of lightweight, stable, good biocompatibility and moderate price, because it is not absorbed by the human body, it can withstand multiple times of high temperature and high pressure disinfection, and avoid the problem of bone flap pollution. As a result, titanium mesh is generally considered safer than autologous bone. It has high toughness and strength, is effective against external shocks, and rarely causes rejection or allergic reactions. In addition, titanium mesh also has good ductility, tissue compatibility and corrosion resistance, and is resistant to wear, not easy to deform, and the incidence of postoperative subcutaneous effusion is also low.

 

 

Titanium mesh repair of the skull, is a covered repair, titanium mesh material is slightly larger than the size of the bone window, covered in the upper layer of the bone window, titanium mesh material not only covers the bone window cavity, and the material and the bone window periphery have overlapping coverage. Although the titanium mesh is relatively light and thin, the titanium mesh itself also has a certain thickness after all, so the connection between the edge of the titanium mesh and its own skull will have a certain convex and concave feeling, which can be touched by hand. And because the edge of the titanium mesh is sharp, it may also cause cutting damage to the scalp, and even due to the tension of the material itself, the edge of the titanium mesh may be deformed and protruding, resulting in scalp breakage and exposure of the titanium mesh material. This is very dangerous. Another disadvantage is that because the titanium mesh is relatively light and thin, the hardness is not enough, and it is easy to deform and collapse if it is subjected to external force. There are many other problems in the repair of the skull with titanium mesh, such as postoperative infection rejection, unsatisfactory shaping effect, affecting CT magnetic resonance examination, and postoperative patient sensitivity to the external hot and cold environment.

 

 

Advantages of titanium mesh:

Light weight, good stability and strong biocompatibility.

It can withstand repeated high-temperature autoclaving to avoid bone flap contamination.

High strength, good toughness and strong impact resistance.

Rejection or anaphylaxis is rare.

Good ductility, strong tissue compatibility, corrosion resistance, wear resistance.

The incidence of postoperative subcutaneous effusion is low.

 

Titanium mesh disadvantages:

The plasticity is poor, and it is not easy to adjust during surgery.

Preoperatively, the implant is prefabricated and individualized by computer-aided design (CAD), and the whole process takes about 2 weeks.

After surgery, patients may experience discomfort in extreme weather, such as headaches and other neurological symptoms, due to strong

thermal conductivity.

During postoperative CT or MRI imaging, due to its high brightness, artifacts may be produced, which may affect image quality, and it is

difficult to judge the formation of hematoma or tumor.

 

PEEK

PEEK repairs the skull, which is an embedded repair. Through 3D printing technology, the shape and size of PEEK material are completely consistent with the bone window, which can be accurately embedded in the bone window, and the edge of the PEEK material is accurately connected with the edge of the bone window, and the connection is smooth. Even if you touch this seam directly, it will feel very smooth, and the human scalp also has a certain thickness, and the thickness of the scalp to the skull is about one centimeter or so, so after PEEK repairs the skull, the hand generally cannot touch the gap at the junction through the scalp, and the touch is very smooth. In addition, PEEK material has excellent performance in all other aspects, and is comparable to the autologous skull in terms of hardness, stiffness, elasticity, stability, thermal insulation, histocompatibility, plasticity, radiation transmission, magnetic field compatibility, etc., and the effect is particularly good in clinical application, which has become a new trend of cranial repair materials.

 

 

Introduction to PEEK materials

Polyetheretherketone (PEEK) is a linear semi-crystalline thermoplastic polymer, which was first applied to the medical field in 1998 by the British company Invibio and approved by the US FDA. Since then, PEEK has been widely used in medicine, especially in skull repair. Due to its excellent plasticity and long-term stability, PEEK material is widely used in the medical field and is readily available.

 

Compared with titanium mesh, PEEK material has the following obvious advantages:

 

Merit:

Personalized (precision repair) :PEEK materials can be reconstructed in 3D according to CT data, accurately matching the shape and thickness of the patient's defects, especially for irregularly shaped bone defects, such as the repair of periorbital and zygomatic regions, and has high value in plastic restoration.

 

Good image compatibility: PEEK does not produce artifacts in imaging tests or EEG examinations, so it does not affect radiation therapy.

 

Improved patient comfort: Due to the low thermal and electrical conductivity of PEEK, it can effectively avoid hot and cold stimuli, improve the postoperative comfort of patients, and has a good tolerance with skull tissue.

 

Good cosmetic restoration: PEEK material can achieve complex craniomaxillofacial contour restoration that is difficult to achieve with traditional prosthetic materials. Compared with titanium mesh, PEEK's elastic and energy-absorbing properties are closer to those of bone, with excellent mechanical properties, high strength, and strong bending resistance, which can provide better protection for the missing skull area.