Spine, Arthroplasty, and Major Joint Replacement Coding
Spine coding
Spine codes are built on approach (anterior, posterior, lateral), level or interspace, and procedure (decompression, discectomy, corpectomy, fusion, instrumentation). Count interspaces, not vertebrae: a fusion from L4 to L5 is one interspace. Combined anterior and posterior fusions are separately reported with modifier 51 when allowed. Some instrumentation codes are add-ons and must follow a primary fusion. Bone graft harvest is reported separately when a distinct site is harvested; local graft is included.
Arthroplasty and revision
Total joint codes describe the primary procedure and include the implant, trial components, and closure. Partial (unicompartmental) knee replacement and hemiarthroplasty are distinct codes, not total joint codes. Revision codes are component-based: acetabular shell only, femoral stem only, or both components. Read the note list of removed and replaced parts; that list selects the revision code. Removal of hardware without replacement and antibiotic spacers have their own codes. Bilateral procedures use modifier 50 when the payer accepts it; otherwise report two lines with LT and RT.
Traps
- Calling a revision a conversion without checking the code definitions.
- Reporting bone graft separately when it is included in the fusion code.
- Counting vertebrae rather than interspaces.
- Missing the second joint in a bilateral replacement.
Rule of thumb: for revisions, let the operative note component list, not the title, choose the code.
Worked example: Revision total hip arthroplasty with a new acetabular shell and a new femoral stem: report the both-component revision code (for example, 27134) rather than two single-component codes.