M22.4 is a "category code," which means it's non-billable. Billable codes require more specificity. Use the list below to navigate to codes that are more specific:
10
M22.40
Chondromalacia patellae, unspecified knee
Billable
10
M22.41
Chondromalacia patellae, right knee
Billable
10
M22.42
Chondromalacia patellae, left knee
Billable