An orthosis, also called a brace, is an orthopaedic device used to support or correct an injured body part. A splint, an ankle brace or a lumbar corset are examples of orthoses.
Orthoses can be articulated, as in the case of knee braces, or static, such as wrist splints.
As for prostheses, they replace a wounded body part. Examples of prostheses are total hip prostheses (THP) or total knee prostheses (TKP).
Your physiotherapist is qualified to recommend an orthosis following a specific assessment of your muscles, ligaments and joints.
If a prosthesis is an option, your physiotherapist is qualified to refer you to the appropriate specialist, who will assess the need to proceed with the installation of a prosthesis.