M76.50 classifies patellar tendinitis — inflammation of the tendon connecting the kneecap to the tibia, commonly called jumper's knee — when the treating clinician has not documented which knee is affected.

Documentation tips

What should appear in the chart to support M76.50.

Source · Editorial brief grounded in 5 cited references ↓

• Record laterality explicitly — 'right knee' or 'left knee' — so you can assign M76.51 or M76.52 instead of the unspecified M76.50.
• Note the clinical basis for the diagnosis: localized patellar tendon tenderness, pain with resisted knee extension, or imaging findings such as ultrasound or MRI showing tendon thickening or intratendinous signal change.
• Document whether this is an acute flare or chronic/recurrent presentation, and the activity or sport that precipitates symptoms (e.g., basketball, volleyball), to support medical necessity for physical therapy or injection.
• If conservative treatment history is relevant to the plan — failed PT, NSAIDs, activity modification — capture it in the note to support higher-intensity interventions.
• Distinguish patellar tendinitis from patellofemoral pain syndrome (M22.2x1) in the assessment; the two conditions require different codes and have different treatment pathways.

Related CPT procedures

Procedure codes commonly billed with M76.50. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

Common coding pitfalls

The recurring mistakes coders make with M76.50 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

• Using M76.50 when laterality is documented elsewhere in the record (e.g., the HPI or imaging report names the side) — always query the full note before defaulting to unspecified.
• Coding bilateral patellar tendinitis with M76.50 instead of assigning both M76.51 and M76.52; the unspecified code does not represent bilateral involvement.
• Confusing patellar tendinitis (M76.5x) with patellofemoral pain syndrome (M22.2x1) — they are Excludes2 of each other at the category level, meaning both can coexist, but each must be coded to its own correct code.
• Assigning M76.50 for a telehealth or cross-coverage encounter where the originating provider's note clearly documented laterality — pull the source documentation before defaulting.
• Applying a 7th-character extension to M76.50 — M-codes in this section do not use encounter-type 7th characters (A/D/S); that convention applies to S-code injury codes only.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Sibling codes

Other billable codes under M76.5 (laterality / anatomic variants).