Orthosis is an externally applied device that supports, aligns, prevents, or corrects musculoskeletal deformity, or improves function. It is a **device** (not a disease or procedure) used across orthopedics, rehabilitation, neurology, and sports medicine. An Orthosis may be temporary (e.g., after injury) or long-term (e.g., for chronic weakness or deformity). In practice, it is commonly discussed during evaluation of gait, joint stability, pain, and functional limitation.

A Brace is an external support device used to position, protect, or assist a body region. It is a medical device (an orthosis), not an anatomic structure or a diagnostic test. It is commonly used in orthopedics, sports medicine, rehabilitation, and postoperative care. It can be off-the-shelf or custom-made depending on the clinical goal and patient anatomy.

A Splint is a device used to support and limit motion of an injured or painful body part. It is an orthopedic **device** (a form of external immobilization) rather than a diagnosis. It is commonly used in emergency care, fracture clinics, sports medicine, and postoperative settings. It can be temporary (acute injury) or part of a longer treatment plan, depending on the case.

A Cast is a rigid external immobilization device used to hold an injured limb in a stable position. It is a medical device, not a diagnosis, and it is most commonly used in orthopedic and emergency care. A Cast is designed to limit movement of bones and joints to support healing and protect soft tissues. It is typically applied after trauma (such as fractures) or after certain orthopedic procedures.

K Wire is a thin, smooth metal pin used to hold bone fragments or joints in a stable position. It is a **device** (orthopedic implant) most commonly used for **temporary fixation** in fracture care and hand/foot surgery. K Wire is typically inserted percutaneously or through a small incision, often with fluoroscopic guidance. It is frequently used in emergency, trauma, and elective orthopedic procedures as a simple, versatile fixation option.

Screw Fixation is the use of orthopedic screws to hold bone or bone fragments in a stable position. It is a surgical concept and device-based method used in fracture care and reconstructive orthopedics. It is commonly performed in trauma, sports medicine, foot and ankle, hand, and spine practice. It aims to support bone healing by controlling motion at the injury or fusion site.

Plate Fixation is a method of stabilizing a bone using a metal plate and screws. It is a **procedure** and an **internal fixation device construct** used in orthopedic surgery. It is most commonly used to treat fractures and to support planned bone cuts (osteotomies). It is discussed in trauma, sports, and reconstructive orthopedics across many body regions.

Orthopedic Implant is a medical device placed in the musculoskeletal system to support, replace, or stabilize bone and joints. Orthopedic Implant is a device category, not an anatomy structure or a diagnosis. It is commonly used in fracture fixation, joint replacement, spine surgery, and deformity correction. In practice, it is discussed when planning surgery, interpreting imaging, and monitoring healing and function over time.

A Prosthesis is an artificial device that replaces a missing body part or helps restore a lost function. It is a medical device concept used in orthopedics, rehabilitation medicine, dentistry, and surgical specialties. In musculoskeletal care, it commonly refers to limb prostheses and joint replacement components. It is used in practice to improve mobility, stability, alignment, and participation in daily activities.

Allograft is tissue transplanted from one human donor to a different human recipient. It is a clinical concept and biologic “material,” not a single procedure or device. In orthopedics, Allograft commonly refers to donor bone, tendon, ligament, meniscus, or cartilage used to reconstruct or replace damaged tissue. It is used across sports medicine, trauma, spine, and joint reconstruction.