Radiology Coding Alert

Remember that joints have their own MRI codes.

Thanks to the multiple joints, muscles, tendons, and ligaments that exist throughout a patient’s extremities, pinpointing the correct magnetic resonance imaging (MRI) code can be tricky. Radiology Coding Alert has pulled together helpful guidance to ensure you’re ready to accurately assign leg, foot, and joint MRI codes when the reports come into your workflow.

Dive into lower extremity MRI coding with these tips and real-world scenarios.

Learn the Lower Extremity MRI Codes

The CPT^® code set includes several codes dedicated to lower extremity MRI procedures. Aside from the use of contrast materials, “The main difference between the two code sets lies in the CPT^® code descriptions of the primary/parent codes,” says Taylor Berrena, COC, CPC, CPB, CRC, CEMC, CFPC, CHONC, coder II at MD Anderson Cancer Center at Cooper in Yorktown, Virginia.

If your radiologist images a patient’s lower extremity, you’ll choose the appropriate code from the following code ranges:

• 73718-73720 [Magnetic resonance (eg, proton) imaging, lower extremity other than joint …]
• 73721-73723 [Magnetic resonance (eg, proton) imaging, any joint of lower extremity …]

Examine the following scenarios to understand which lower extremity MRI codes apply.

Analyze This Sprained Ankle Encounter

Scenario: A patient presents to urgent care complaining of ankle pain. The patient said they rolled their ankle when they stepped off the side of the road while on a run. The physician ordered two-view ankle X-rays, which didn’t reveal a fracture. The physician then ordered an ankle MRI with contrast for further evaluation. After reviewing the MRI results, the physician diagnosed the patient with a sprained anterior talofibular ligament (ATFL) of the left ankle.

For this scenario, you’ll assign 73600 (Radiologic examination, ankle; 2 views) to report the two-view ankle X-rays. Next, you’ll turn your attention to the MRI test. The radiologist performed an MRI with contrast of the patient’s ankle, so you’ll look to the “any joint of lower extremity” codes to make your code selection. In this case, 73722 (Magnetic resonance (eg, proton) imaging, any joint of lower extremity; with contrast material(s)) is the correct choice since it covers an ankle MRI and includes the use of contrast.

Here’s why: “The 73721-73723 [Magnetic resonance (eg, proton) imaging, any joint of lower extremity …] code set should be utilized if the anatomic area being imaged is a joint, such as the ankle, knee, and hip joints, but the 73718-73720 [Magnetic resonance (eg, proton) imaging, lower extremity other than joint …] code set should be utilized if the anatomic area being imaged is a part of the lower extremity that is not a joint, such as the femur, tibia, or fibula,” Berrena says.

ICD-10-CM: The S93.4- (Sprain of ankle) code subcategory has codes designated for sprains of different ankle ligaments, including the calcaneofibular ligament, deltoid ligament, and tibiofibular ligament, but there isn’t a specific subcategory for the ATFL. Therefore, you’ll assign S93.492A (Sprain of other ligament of left ankle, initial encounter) to report the sprained ATFL.

Know What MRI Code is Needed for a Knee Examination

Scenario: A patient presents to the emergency department (ED) after suffering an injury while skateboarding. The patient attempted a trick, fell, and hurt their knee. The physician ordered an MRI without and with intravascular (IV) contrast to assess the knee for ligament damage. After reviewing the results, the physician diagnosed the patient with a torn anterior cruciate ligament (ACL) and a torn posterior cruciate ligament (PCL) in the right knee.

In situations like this, “Another challenge or common mistake to be aware of when reporting lower extremity MRI codes is verifying whether contrast has been administered,” Berrena says. In this scenario, the radiologist performed the knee MRI without contrast, reviewed the images, administered IV contrast, and then captured additional images. You’ll assign 73723 (… without contrast material(s), followed by contrast material(s) and further sequences) to report the knee MRI procedure.

Remember: To report a procedure that used contrast materials, the documentation must include written evidence indicating the IV administration of contrast materials according to the CPT^® guidelines at the beginning of the Radiology section.

ICD-10-CM: The physician diagnosed the patient with a torn ACL and a torn PCL in the right knee. When you search for Tear, torn (traumatic) > ligament in the ICD-10-CM Alphabetic Index, you’ll be redirected to Sprain. Under Sprain > knee > cruciate ligament, you’ll find anterior and posterior codes, which you can verify in the Tabular List.

You’ll assign S83.511A (Sprain of anterior cruciate ligament of right knee, initial encounter) to report the torn ACL and you’ll assign S83.521A (Sprain of posterior cruciate ligament of right knee, initial encounter) to report the torn PCL. While each of these code descriptors feature the word “sprain,” the codes are correct for the torn ligament diagnoses.

Why? Parent code S83.- (Dislocation and sprain of joints and ligaments of knee) features an Includes note that covers “traumatic rupture of joint or ligament of knee.”

Scrutinize Descriptors to Report Shin Splints

Scenario: A 35-year-old patient presented to their primary care physician (PCP) with complaints of severe leg pain after running for the past two to three weeks. The physician referred the patient to your radiology practice for an MRI of the patient’s legs. The radiologist performed the procedure on both legs without contrast and interpreted the results. The radiology report listed the findings as shin splints in both legs.

As a radiology coder, you’ll report the radiologist’s actions in this scenario. Assign 73718 (Magnetic resonance (eg, proton) imaging, lower extremity other than joint; without contrast material(s)) to report the leg MRI. Depending on your individual payer preferences, you’ll need to append modifier 50 (Bilateral procedure) to 73718 or you’ll report two instances of 73718 with modifiers LT (Left side) and RT (Right side) appended to each code. Adding the laterality modifiers to 73718 indicate that the radiologist performed the procedure on both sides of the patient’s body. This is necessary since 73718 is a “per extremity” code, which means the code only applies to one leg at a time, unless appended with a modifier.

ICD-10-CM: Look for “Shin splints” in the ICD-10-CM Alphabetic Index, where you’ll find S86.89- (Other injury of other muscles and tendons at lower leg level). When you turn to the Tabular List to verify the code, you’ll find the code features a 6th character required icon to indicate laterality. You’ll also need a 7th character to designate the stage of treatment for the condition.

You’ll assign the following codes for an initial encounter for shin splints in the right and left legs:

• S86.891A (Other injury of other muscle(s) and tendon(s) at lower leg level, right leg, initial encounter)
• S86.892A (Other injury of other muscle(s) and tendon(s) at lower leg level, left leg, initial encounter)