Traumatic, Pathological, or Stress Fracture: Which Family, and the Osteoporosis Rule

The classification files fractures by why the bone broke, not by which bone. The Alphabetic Index has separate main terms for each cause, and the tabular keeps them apart with Excludes1 notes in every direction.

Two Index details matter. “Fracture, traumatic” is the default: a fracture documented with no cause at all lands there, at T14.8 for an unspecified site or the S code for a named one — and its own “see also Fracture, pathological” cross-reference is the Index telling the coder the other family exists. And the stress fracture is filed under “Fracture, traumatic” as a subterm, yet codes to M84.3-, not to an S code: the Index groups it with injuries for lookup, the tabular classifies it with disorders of bone continuity.

Every one of these subcategories names the others in an Excludes1 note. M84.3 excludes pathological fracture NOS (M84.4-), pathological fracture due to osteoporosis (M80.-) and traumatic fracture (S12.- through S92.-). M84.4 excludes M84.5-, M80.-, M84.6-, M84.3- and the traumatic codes. M80 excludes pathological fracture NOS (M84.4). Category M84 as a whole carries an Excludes2 for traumatic fracture — “see fracture, by site” — because a patient can of course have a traumatic fracture of one bone and a pathological fracture of another; what the Excludes1 notes forbid is two families for the same fracture.

That is what a Claim Check flag on, say, a stress-fracture code with an S32 sacral fracture code is asking: are these two different fractures, or one fracture coded twice? For one fracture the record has to settle the cause, and only one family survives. The Excludes1 guide linked below covers how to read that note when the two conditions really are separate.

The most consequential sentence in this area is in Section I.C.13.d.2:

“Category M80, Osteoporosis with current pathological fracture, is for patients who have a current pathologic fracture at the time of an encounter. The codes under M80 identify the site of the fracture. A code from category M80, not a traumatic fracture code, should be used for any patient with known osteoporosis who suffers a fracture, even if the patient had a minor fall or trauma, if that fall or trauma would not usually break a normal, healthy bone.”

So the presence of a fall in the history does not put the fracture in the injury chapter. With known osteoporosis, the question is whether the mechanism would have broken a healthy bone — and that judgement belongs to the provider’s documentation, not to the coder. M80’s Includes note says the same in different words: “osteoporosis with current fragility fracture.”

The guideline’s preamble adds the point that trips site coding: “Osteoporosis is a systemic condition … The site codes under category M80, Osteoporosis with current pathological fracture, identify the site of the fracture, not the osteoporosis.” And once the fracture has healed, the code changes family again: category M81, Osteoporosis without current pathological fracture, “even if they have had a fracture in the past,” with Z87.310, Personal history of (healed) osteoporosis fracture, following it.

Pathological and stress fractures (M80, M84.3, M84.4, M84.5, M84.6) share one six-value set: A initial encounter for fracture, D subsequent with routine healing, G delayed healing, K nonunion, P malunion, S sequela. Traumatic fractures of the long bones carry the larger set that also encodes open-fracture type — A, B, C for initial encounters by closed / open type I–II / open type IIIA–C, and D through R for the subsequent variants.

The meaning of A is the same everywhere. Section I.C.13.c, for pathological fractures: “7th character A is for use as long as the patient is receiving active treatment for the fracture. While the patient may be seen by a new or different provider over the course of treatment for a pathological fracture, assignment of the 7th character is based on whether the patient is undergoing active treatment and not whether the provider is seeing the patient for the first time.” Section I.C.19.c.1 says the same for traumatic fractures and adds that the initial-encounter character “should also be assigned for a patient who delayed seeking treatment for the fracture or nonunion.” Two defaults apply only on the traumatic side: “A fracture not indicated as open or closed should be coded to closed. A fracture not indicated whether displaced or not displaced should be coded to displaced.” The 7th-character guide linked below walks the phases in full.

1. Eighty-year-old with documented osteoporosis slips from standing and fractures the right femoral neck; admitted for repair. Known osteoporosis plus a mechanism the provider documents as one that would not usually break healthy bone: M80.051A, Age-related osteoporosis with current pathological fracture, right femur, initial encounter. Not S72.001A. M80 also asks, by Use Additional Code note, for a major osseous defect code (M89.7-) if applicable.
2. Same fracture in a patient with no bone disease, after a fall from a ladder. Traumatic: S72.001A, Fracture of unspecified part of neck of right femur, initial encounter for closed fracture — closed by default, since the record does not say open — with an external cause code for the fall.
3. Distance runner with right-foot pain; imaging shows a metatarsal stress fracture; no injury event. Stress: M84.374A, Stress fracture, right foot, initial encounter for fracture, with the external cause code M84.3’s Use Additional note asks for.
4. Vertebral fracture documented as pathological; workup for the underlying cause is still pending at discharge.M84.48 — the Index entry “Fracture, pathological, vertebra” points there, the “Pathological fracture NOS” family — moving to M80.-, M84.5- or M84.6- only when the cause is documented, and then with the Code Also the neoplasm or underlying-condition note those subcategories carry. One word changes the family: a vertebral compression fracture documented without “pathological” or a cause is M48.5-, Collapsed vertebra, whose inclusion terms are “Compression fracture of vertebra NOS” and “Wedging of vertebra NOS,” and whose Excludes1 names every fracture family — M80.-, M84.4-, M84.58, M84.68, M48.4- and the traumatic S codes.

1. Establish the cause from the record: an injury, a diseased bone (osteoporosis, neoplasm, other disease), repetitive stress, or a pathological fracture with no cause named.
2. Known osteoporosis plus a fracture → M80 at the fracture site, even after a minor fall (I.C.13.d.2).
3. Injury with no bone disease → the S code by site; closed and displaced by default; external cause code.
4. Stress fracture → M84.3- with the external cause code; neoplasm → M84.5- with Code Also the neoplasm; other disease → M84.6-; cause not stated → M84.4-.
5. Vertebral “compression fracture” with no cause and not called pathological → M48.5-.
6. Apply the 7th character: A during active treatment regardless of which provider; D routine healing; G/K/P complications of healing; S sequela.

• An S code for a fracture in a patient with known osteoporosis because a fall occurred.
• Two families for one fracture — the Excludes1 notes allow one.
• M84.4- for a vertebral compression fracture with no cause documented — M48.5-.
• 7th character D for a first visit to a new provider during active treatment.
• M14.6- / M80.- for a healed fracture — M81 with Z87.310 once healed.

• Known osteoporosis or another bone disease, and the provider’s characterization of the mechanism.
• The words “pathological,” “stress,” “fatigue,” “insufficiency,” “compression,” “traumatic.”
• Open or closed, displaced or not — absent, the defaults apply.
• Phase of care for the 7th character.