PEEK Precision: the advantages of PEEK materials in medical implants

Gautam Gupta, Ph.D., senior vice president and general manager, medical devices, 3D Systems pinpoints the advantages for PEEK materials in medical device implants.

Medical device manufacturers need innovative ways to bring high-quality, reliable products to market faster. 3D printing has rapidly gained traction as a technology that can produce intricately designed medical devices such as spine cages. With the release of faster, multi-laser systems, manufacturers can cost-effectively expand applications to larger implants for the shoulder, hip, and knee. Additive manufacturing (AM) also enables the design and efficient production of patient-specific implants and instrumentation. Now, with the ability to 3D print implants in Polyetheretherketone, more commonly known as PEEK, manufacturers are exploring the possible applications to capitalise on the tremendous advantages this high-performance polymer has to offer. 

PEEK has mechanical properties such as high strength, durability, and fatigue resistance that are close to those of human bone, enabling enhanced load-bearing performance and reduced risk of stress shielding. PEEK is also radiolucent which helps improve visibility in medical imaging to determine how the bone is healing, for example, as part of tumour surgery.  

Harnessing the virtues of PEEK with 3D printing 

While PEEK is well-known within the orthopaedics market, most PEEK implants are still produced using conventional manufacturing methods like machining, turning, or injection moulding due to misconceptions about the ability to 3D print PEEK. These likely arise from the early days of 3D-printed PEEK implants when the constructs often did not show the same mechanical properties exhibited by traditionally manufactured parts. 3D Systems has been able to change this perception due to the proprietary 3D printing technology. This printer’s integrated cleanroom and temperature controls with a laminar airflow make it ideal for the rapid manufacture of biocompatible, sterilisable medical devices. The combination of PEEK and 3D System’s extrusion-based platform enables design flexibility to create complex, patient-specific geometries.  

Revealing the potential of PEEK implants 

The promise of implants that are additively manufactured using PEEK is already being realised. The solution has most notably seen successes in cranial implants, spinal cages, and bone plates for trauma. 

Earlier this year, University Hospital of Salzburg (Austria) successfully applied 3D Systems’ portfolio of point-of-care additive manufacturing technologies to design and produce its first 3D-printed PEEK cranial implant as a custom device for a 55-year-old male suffering from a skull deformity. Brought together by the hospital’s in-house clinicians, the team used Oqton’s D2P software to create 3D models from the patient's CT images and Geomagic Freeform to complete the design of the patient-specific occipital prosthesis. The cranial implant was printed using VESTAKEEP i4 3DF PEEK by Evonik on 3D Systems’ EXT 220 MED (formerly the Kumovis R1) extrusion platform.  

Implants play a pivotal role in treating craniomaxillofacial trauma. In these situations, time is of the essence to get the patient into surgery and provide critical care. The ability to rapidly produce patient-specific cranial and orbital implants from PEEK has the potential to not only provide care as efficiently as possible but also can help enable a better outcome and healing for the patient. Producing these plates using PEEK enables lightweight plates yet perhaps not the durability required to facilitate healing. In these cases, carbon-fiber-reinforced (CFR) PEEK is showing promise. The modulus of CFR-PEEK is the closest to that of human bone, which enables strength and durability. CFR-PEEK also provides higher osteoconductivity and allows for better osseointegration and implant fixation. Additionally, CFR-PEEK’s radiolucency allows the ability to track bone healing while assessing the surrounding tissues and monitoring the implant's performance. 

Peeking into the future 

Hospital-based printing with PEEK shows great promise as the material can be printed quickly, is biocompatible, requires minimal post-processing, and can be used for a broad range of both standard and personalised implants. Combining PEEK with an advanced extrusion platform can help facilitate this new frontier. As these technologies become more user-friendly for medical professionals, more hospitals will be able to implement additive manufacturing at the point of care as part of an end-to-end solution for personalised surgery.