The root operation of fusion is defined as which of the following?

The root operation of fusion in the ICD-10-PCS coding system is defined as "joining two parts." This operation typically involves the surgical procedure of permanently joining two adjacent bones or joints, often to eliminate motion and reduce pain caused by conditions such as arthritis or other degenerative diseases. The process creates a single, solid structure from what were previously separate parts.

In the context of the options provided, understanding fusion focuses on the concept of merging anatomical structures to form a cohesive entity, which encapsulates the essence of this root operation. This joining can improve functionality or reduce discomfort, making it a significant intervention in various orthopedic and neurological procedures.

The other options describe different types of root operations that do not align with the definition of fusion. For instance, breaking up solid matter pertains to fragmenting solid tissues, while separating body parts deals with splitting or detaching structures, and closing an orifice involves suturing or sealing an opening. None of these accurately capture the intent or method of fusion, reinforcing why joining two parts is the correct characterization.