73721
MRI lower extremity joint, without contrast
Magnetic resonance imaging of any joint of the lower extremity (typically knee or ankle), without contrast material. CMS 2026 global wRVU 1.48, total RVU approximately 7.18, Medicare global allowable approximately $240. The workhorse outpatient joint MRI for internal derangement, ligament tear, and meniscal pathology.
When to use it
Use 73721 for knee, ankle, foot, or hip joint MRI without contrast. Most common indication: knee internal derangement evaluation (meniscal tear, ACL/PCL/MCL tear, chondral injury) after failed initial conservative management.
Full guidance
Other indications: ankle ligament tear (lateral collateral, syndesmotic), avascular necrosis screening (hip, talus), Achilles or other tendon rupture characterization, occult fracture in trauma. 73722 (with contrast) and 73723 (without and with) are reserved for tumor, infection, or MR arthrogram protocols.
Documentation checklist
- ✓Order with indication and joint specified.
- ✓MRI safety screen.
- ✓Interpretation report identifying the joint, covering bones, articular cartilage, ligaments, tendons, menisci (if knee), muscles, neurovascular bundles, and any incidental findings.
- ✓Document specific findings (e.g., medial meniscus posterior horn radial tear; ACL complete intrasubstance tear; Grade 4 patellofemoral chondromalacia).
- ✓Setting modifier; radiologist signature.
Common pitfalls
- !Billing 73721 for a non-joint lower extremity study. Non-joint MRI of the lower extremity (e.g., calf soft tissue mass) is 73718 (without), 73719 (with), 73720 (without and with).
- !Billing 73721 plus 73722 on the same date. The combined code is 73723.
- !Confusing knee MR arthrogram (which is 73722 plus 27093 if intra-articular contrast is injected) with a standard non-contrast knee MR.
- !Failing to document failed conservative care for non-urgent outpatient knee MRI. Most commercial payers deny without 4 to 6 weeks of conservative management on the record.
- !Reading a 73721 of the ankle and billing as if it were a foot study. The joint specified in the report and order should match billing.
Payer notes
Medicare covers 73721 for appropriate joint MRI indications. Commercial payers commonly require prior auth and documentation of failed conservative care. Worker's comp varies by carrier. Bilateral studies should be billed twice with modifier RT and LT on each side, not modifier 50 (which is reserved for codes with a CMS-defined bilateral indicator).