M76.71 identifies inflammation of the peroneal tendons (peroneus longus and/or brevis) along the lateral aspect of the right lower leg, classified as a lower-limb enthesopathy under the musculoskeletal chapter.

Documentation tips

What should appear in the chart to support M76.71.

Source · Editorial brief grounded in 5 cited references ↓

• Explicitly name the affected side ('right') in both the assessment and the plan — a laterality mismatch between note sections is an audit flag.
• Record physical exam findings specific to the peroneal tendons: tenderness posterior to the lateral malleolus, pain with resisted eversion, and any swelling along the tendon sheath.
• Document imaging results that support the diagnosis: MRI findings such as tendon thickening, peritendinous edema, or longitudinal splits distinguish tendinitis from a tear and justify the M76.71 selection over a rupture code.
• Note chronicity and any prior conservative treatment (physical therapy, bracing, NSAIDs) if surgical intervention is being considered — this supports medical necessity for advanced imaging or procedural authorization.
• If an injection is performed, document the exact injection site (peroneal tendon sheath, right) to align the procedure code with the diagnosis code and satisfy LCD requirements.

Related CPT procedures

Procedure codes commonly billed with M76.71. 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 M76.71 and adjacent codes.

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

• Using M76.70 (unspecified leg) when the note clearly documents the right side — always code to the highest specificity supported by documentation.
• Coding M76.71 when operative or MRI findings show a peroneal tendon tear or rupture; tendinitis and tear are distinct pathologies with different code families.
• Failing to add M76.72 when bilateral peroneal tendinitis is documented — there is no single bilateral code, so both laterality-specific codes are required.
• Confusing peroneal tendinitis (M76.71) with posterior tibial tendinitis (M76.821); both affect the medial/lateral ankle region but are explicitly separated in the tabular list.
• Omitting the diagnosis code from injection claims billed under 20551, which triggers medical necessity denials from Medicare and commercial payers that cross-reference the LCD for tendon injections.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Sibling codes

Other billable codes under M76.7 (laterality / anatomic variants).