ICD-10-CM · Knee

M22.00

Chronic, non-traumatic condition in which the patella repeatedly displaces from the trochlear groove, coded here when the treating clinician has not specified whether the right or left knee is affected.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 7
Region: Knee

Drawn from CDCICD10DataAAPCOutsourcestrategies

Documentation tips

What should appear in the chart to support M22.00.

Source · Editorial brief grounded in 5 cited references ↓

Specify laterality (right or left knee) in every note — M22.00 is the fallback for unspecified side and triggers audit scrutiny.
Document the recurrent pattern explicitly: note the number of prior dislocation episodes, timeframe, and whether each event was atraumatic or low-energy.
Record conservative treatment history (bracing, physical therapy, activity modification) before surgical planning, as payers often require failed conservative care documentation.
Distinguish dislocation (complete displacement, M22.0x) from subluxation (partial displacement, M22.1x) in the clinical impression — the terms are not interchangeable for coding.
If imaging was performed, include findings such as trochlear dysplasia, patella alta, or medial patellofemoral ligament (MPFL) insufficiency, which support medical necessity for surgical intervention.

Related CPT procedures

Procedure codes commonly billed with M22.00. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

27422 $698.75

Reconstruction of a dislocating patella using extensor mechanism realignment, muscle advancement, or soft-tissue release techniques (e.g., Campbell or Goldthwaite-type procedures).

27420 $705.09

Surgical reconstruction of a chronically dislocating patella, typically involving transfer of the patellar tendon insertion as a bone block to restore stable tracking.

27438 $781.92

Patellar arthroplasty with insertion of a prosthetic implant to resurface the kneecap.

27447 $1,159.35

Knee replacement surgery addressing both the medial and lateral tibiofemoral compartments, with or without resurfacing of the patella.

29877 $586.85

Knee arthroscopy with surgical debridement or shaving of articular cartilage (chondroplasty) — does not include meniscal work.

73564 $49.43

Radiologic examination of the knee consisting of four or more views, including oblique and tunnel projections, for a complete diagnostic workup.

73560 $34.40

Radiologic examination of the knee joint, one or two views, unilateral.

Common coding pitfalls

The recurring mistakes coders make with M22.00 and adjacent codes.

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

Using M22.00 when laterality is actually documented — if the note says 'right' or 'left,' you must use M22.01 or M22.02 respectively; defaulting to unspecified is a specificity error.
Coding M22.00 for a first-time acute traumatic patellar dislocation — that event belongs under S83.0- (traumatic dislocation of patella) per the M22 Excludes2 note.
Confusing recurrent dislocation (M22.0x) with recurrent subluxation (M22.1x) — always confirm the clinical term used by the provider before selecting between these two subcategories.
Failing to capture bilateral involvement with two separate laterality-specific codes (M22.01 + M22.02) when both knees are documented — M22.00 alone does not communicate bilateral disease.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M22.00 applies when a patient has a documented history of recurrent (non-traumatic) patellar dislocation and the affected side is not identified in the clinical record. The key clinical picture is multiple instability episodes — not a single acute event. An Excludes2 note at the M22 category level bars simultaneous use with acute traumatic patellar dislocation (S83.0-); that means a first-time traumatic event goes to S83.0-, while a pattern of repeated instability without an acute trauma trigger belongs in the M22.0 family.

Laterality drives code selection within M22.0: M22.01 for right knee, M22.02 for left knee, and M22.00 only when the note genuinely omits side. If documentation is unclear, query the provider before defaulting to M22.00 — specificity is auditable and affects DRG assignment. MS-DRGs 562 and 563 (Fracture, Sprain, Strain and Dislocation, except femur/hip/pelvis/thigh) capture encounters coded with M22.00.

For recurrent subluxation — a partial displacement rather than full dislocation — use M22.1x instead. Do not conflate the two: dislocation is complete displacement; subluxation is partial. When the note describes patellofemoral pain or chondromalacia without instability episodes, M22.2Xx (patellofemoral disorders) or M22.3Xx (other derangements) is the appropriate family.

Sibling codes

Other billable codes under M22.0 (laterality / anatomic variants).

M22.01

Recurrent dislocation of patella, right knee

M22.02

Recurrent dislocation of patella, left knee

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01When should I use M22.00 instead of M22.01 or M22.02?

Use M22.00 only when the treating provider's note genuinely does not specify which knee is affected. If laterality appears anywhere in the encounter documentation, select M22.01 (right) or M22.02 (left).

02Can M22.00 and S83.0- be coded together on the same encounter?

No. The Excludes2 note at the M22 category level means M22.0x and S83.0- describe different conditions — recurrent non-traumatic instability versus acute traumatic dislocation. They should not be assigned together unless two genuinely distinct clinical events are documented in the same encounter.

03What is the difference between M22.00 and M22.10?

M22.00 is recurrent complete dislocation of the patella (unspecified knee); M22.10 is recurrent subluxation (partial displacement) of the patella (unspecified knee). The provider's clinical distinction between full dislocation and subluxation drives which code is correct — do not choose based on symptom severity alone.

04Which DRGs does M22.00 map to?

M22.00 groups to MS-DRG 562 (with MCC) or 563 (without MCC) under the Fracture, Sprain, Strain and Dislocation except femur, hip, pelvis and thigh grouping (MS-DRG v42.0).

05How do I code bilateral recurrent patellar dislocation?

Assign both M22.01 (right knee) and M22.02 (left knee). M22.00 does not communicate bilateral involvement — it only signals that the side is unknown. Bilateral documentation requires two laterality-specific codes.

06Is M22.00 appropriate after MPFL reconstruction surgery?

M22.00 can support surgical necessity in the pre-operative encounter. Post-operatively, evaluate whether the instability has resolved; if residual instability or a complication exists, continue with the most specific code available. Do not carry the pre-op diagnosis forward without confirming ongoing clinical relevance.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira AI Scribe captures the laterality of each dislocation event, the number and mechanism of prior episodes (atraumatic vs. low-energy), any imaging findings supporting structural instability (trochlear dysplasia, MPFL tear, patella alta), and the conservative care trail. That documentation prevents automatic downgrade to M22.00, protects against a specificity audit flag, and satisfies payer medical necessity criteria for MPFL reconstruction or tibial tubercle osteotomy.

See how Mira captures M22.00 documentation