Tibial collateral bursitis (Pellegrini-Stieda syndrome) of an unspecified leg — inflammation of the bursa adjacent to the tibial collateral ligament at the medial knee, without documented laterality.

Documentation tips

What should appear in the chart to support M76.40.

Source · Editorial brief grounded in 5 cited references ↓

• Document laterality explicitly (right or left leg) at every encounter — M76.40 is a fallback for genuinely unspecified cases, not a default.
• Record the specific anatomic location: medial knee, tibial collateral ligament region, to distinguish from pes anserine or prepatellar bursitis.
• Note imaging findings that support the diagnosis — X-ray or MRI evidence of calcification adjacent to the MCL, soft tissue swelling, or bursal fluid is key for medical necessity.
• Document the mechanism or history (prior trauma, repetitive stress, post-injury calcification) to align with the Pellegrini-Stieda clinical picture.
• If conservative care has been attempted (NSAIDs, PT, corticosteroid injection), document treatment history to support ongoing or procedural management.
• Record functional limitations (range of motion restriction, pain with weight-bearing) to substantiate severity and medical necessity.

Related CPT procedures

Procedure codes commonly billed with M76.40. 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 M76.40 and adjacent codes.

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

• Using M76.40 when laterality is documented in the note — always select M76.41 (right) or M76.42 (left) if the provider specifies a side.
• Confusing Pellegrini-Stieda bursitis with pes anserine bursitis (M70.50-M70.52) or general bursitis NOS (M71.9) — verify the bursa involved is the tibial collateral bursa at the medial knee.
• Coding M76.40 alongside M71.5- (Other bursitis, not elsewhere classified) for the same site — the Excludes2 at M71.5 directs tibial collateral bursitis to M76.4-, preventing duplicate coding at the same location.
• Omitting MCC/CC diagnoses that affect DRG assignment to 557 vs. 558 — missing comorbidities leave reimbursement on the table.
• Billing M76.40 for bursitis caused by overuse or pressure without checking whether M70.- is the more appropriate category per the Excludes2 note on M76.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Sibling codes

Other billable codes under M76.4 (laterality / anatomic variants).