Arthrotomy

Arthrotomy literally means 'cutting into a joint.' The surgeon makes a deliberate incision through the joint capsule to gain direct access to the intra-articular space. This open approach is chosen when the clinical goal—draining a septic joint, excising synovium, retrieving a loose body, or obtaining tissue for pathologic analysis—cannot be reliably achieved through arthroscopic portals alone.

CPT codes for arthrotomy are organized by anatomic site and by what was accomplished inside the joint. For example, the elbow has separate codes depending on whether the procedure addressed infection, loose bodies, or synovial disease. The shoulder, knee, hip, wrist, and small joints of the hand and foot follow the same logic. Because the operative purpose drives code selection, the operative note must state both the joint entered and the definitive work performed—not just 'arthrotomy.'

When arthroscopy is converted to or performed alongside an arthrotomy during the same operative session, modifier 51 is typically appended to the secondary procedure, and the higher-RVU code is listed first. Payers may bundle the two approaches if documentation does not clearly justify distinct work. Laterality modifiers (LT/RT) are required by most payers and are especially important for bilateral or staged cases.

Selecting the wrong arthrotomy CPT code—or defaulting to an unspecified code because the operative note lacks detail—directly reduces reimbursement and can trigger an audit. Many arthrotomy codes have materially different RVU values depending on whether infection, synovectomy, or biopsy was performed; a coder forced to choose the lowest-specificity code because documentation is vague leaves revenue on the table and may mismatch the ICD-10 diagnosis code, creating a medical-necessity denial. Additionally, failing to apply a laterality modifier when the payer requires one is one of the most common causes of clean-claim failure for arthrotomy encounters.