This 2007 narrative review synthesizes polymer science and clinical literature on PEEK and related polyaryletherketones (PAEKs) as orthopedic biomaterials. It covers molecular structure, mechanical properties, radiation stability, biocompatibility, bioactive composite development, and clinical applications from spinal cages to femoral stems. The central question: why does PEEK behave the way it does, and where does the clinical evidence actually stand?
Titanium was the original material for interbody spinal cages — strong, biocompatible, and familiar. Its radiopacity made fusion assessment nearly impossible radiographically, and its stiffness raised concerns about endplate stress shielding.
PEEK solved both problems. When you see a radiolucent cage on postoperative spine imaging, that is not a flaw. It is the design feature that displaced titanium. The Brantigan cage trial (98.9% fusion at 2 years, fusion visible at 100% of levels) is the foundational evidence behind this shift.
When you encounter a bioactive PEEK implant loaded with HA, understand the tradeoff explicitly: HA incorporation improves bone apposition but reduces tensile strength proportionally, with a 45% drop at 40% loading due to particle debonding. High HA fractions are not suitable for primary load-bearing applications.
For sterilization: unlike UHMWPE, PEEK can be gamma sterilized in air without inert packaging. Free radicals decay within 20 minutes. This is why PEEK does not require the careful shelf-life management that polyethylene bearing surfaces demand.
This 2007 narrative review synthesizes polymer science and clinical literature on PEEK and related polyaryletherketones (PAEKs) as orthopedic biomaterials. It covers molecular structure, mechanical properties, radiation stability, biocompatibility, bioactive composite development, and clinical applications from spinal cages to femoral stems. The central question: why does PEEK behave the way it does, and where does the clinical evidence actually stand?
Titanium was the original material for interbody spinal cages — strong, biocompatible, and familiar. Its radiopacity made fusion assessment nearly impossible radiographically, and its stiffness raised concerns about endplate stress shielding.
PEEK solved both problems. When you see a radiolucent cage on postoperative spine imaging, that is not a flaw. It is the design feature that displaced titanium. The Brantigan cage trial (98.9% fusion at 2 years, fusion visible at 100% of levels) is the foundational evidence behind this shift.
When you encounter a bioactive PEEK implant loaded with HA, understand the tradeoff explicitly: HA incorporation improves bone apposition but reduces tensile strength proportionally, with a 45% drop at 40% loading due to particle debonding. High HA fractions are not suitable for primary load-bearing applications.
For sterilization: unlike UHMWPE, PEEK can be gamma sterilized in air without inert packaging. Free radicals decay within 20 minutes. This is why PEEK does not require the careful shelf-life management that polyethylene bearing surfaces demand.