🔩 Classification by Function and Application
Orthopedic implants can be broadly categorized based on their intended use, which determines their design, materials, and mechanical properties.
1. Joint Reconstruction Implants
These are permanent devices used in arthroplasty (joint replacement surgery) to replace the articulating surfaces of a joint that has been severely damaged by arthritis (osteoarthritis, rheumatoid arthritis) or trauma.
Hip Implants: Consist of a socket (acetabular cup) and a ball (femoral head) attached to a stem inserted into the femur. They replace the ball and socket joint of the hip.
Knee Implants: Involve resurfacing the ends of the thigh bone (femur) and shin bone (tibia) with metallic components and inserting a specialized polymer cushion to act as artificial cartilage.
Other Joints: Implants for the shoulder, elbow, and ankle, used for less common but equally debilitating joint degeneration.
2. Trauma and Fracture Fixation Devices
These are temporary or permanent implants used to stabilize bone fractures while the body's natural healing process takes place.
Plates and Screws: Plates are flat metallic strips fixed to the outside of a fractured bone using screws. They hold the bone fragments in correct anatomical alignment until the fracture unites.
Locking Plates are a modern type where the screws lock directly into the plate, creating a stable, fixed-angle construct, particularly useful for complex or osteoporotic fractures.
Intramedullary Nails (IM Nails/Rods): Long metal rods inserted into the central marrow cavity of long bones (like the femur or tibia) to provide strong internal support. They are secured at the ends with locking screws.
Pins and Wires: Smaller implants used to stabilize fractures in small bones (like the hand or foot) or to hold fragments in place temporarily.