Norian is a synthetic bone graft substitute used in orthopedic and craniofacial surgery. This injectable material fills gaps or voids in bone. It provides a temporary framework that supports the body’s natural healing processes. It integrates with existing bone, aiding in reconstruction.
Composition and Function
Norian is primarily composed of calcium phosphate, along with a dilute sodium phosphate solution. These components form a smooth, viscous paste for injection into a bone defect. This blend closely resembles the natural mineral phase of human bone, which is largely made of carbonated apatite.
Once injected, the paste undergoes a chemical reaction, hardening at body temperature. Setting begins in about two minutes and completes within 6 to 10 minutes, depending on the product and temperature. The hardened material provides immediate structural support, much like how plaster sets to form a rigid cast. It reaches its ultimate compressive strength within 24 hours, offering stability during the initial healing phase.
Medical Applications
Norian is used in clinical scenarios where bone voids require filling and support. It is frequently used for traumatic fractures, particularly in areas like the distal radius (wrist), tibial plateau (knee), calcaneus (heel), proximal humerus, and proximal femur. The material can also fill bone defects after the removal of benign bone tumors.
Its injectable nature allows for minimally invasive delivery through small incisions into irregularly shaped bone defects. Its conformability and immediate mechanical support makes it a suitable option for stabilizing fractures and augmenting screws, especially in patients with compromised bone quality. It is also indicated for restoring or augmenting bony contours in the craniofacial skeleton, including the fronto-orbital and malar regions.
The Remodeling Process
After Norian hardens, it serves as a scaffold for new bone growth. This process is known as osteoconduction, where it guides the body’s bone-forming cells. Over several months to years, the body’s natural processes gradually resorb, or dissolve, the synthetic Norian.
Specialized osteoclasts break down the synthetic implant, while osteoblasts (bone-forming cells) simultaneously lay down new, living bone tissue. This ensures the synthetic material is progressively replaced by natural bone. The rate of this remodeling depends on the metabolic activity of the surrounding host bone.
Potential Complications
While Norian is designed to aid bone healing, certain complications can occur. A primary concern is material extravasation: leakage of the unhardened cement from the bone void into surrounding soft tissues or joint spaces. This can happen if the material is inserted with too much force or if there are uncontained gaps in the bone.
Extravasation can lead to a significant inflammatory response in the adjacent tissues, potentially causing pain and delayed wound healing. If cement leaks into a joint, it can damage cartilage or interfere with movement. Another issue is the material’s brittle nature; placing screws too close to the edge of the hardened cement or improper drilling can lead to localized implant fracture.