The ICD-10-CM code for knee pain is M25.561 for the right knee, M25.562 for the left knee and M25.569 for an unspecified knee; there is no bilateral knee pain code, and once the provider confirms a cause such as osteoarthritis or a meniscus tear, you code that condition instead.
Knee pain is a daily diagnosis in primary care, orthopedics, sports medicine, physical therapy and imaging. Because the symptom code is easy to find, it is often reported long after the record supports something more specific, or without the laterality the payer needs to match the procedure line.
The result is avoidable denials: an MRI billed with an unspecified knee, a right-knee diagnosis on a left-knee procedure, or a pain code paired with a confirmed arthritis diagnosis that already explains the pain.
This guide covers the M25.56- codes in the FY2027 ICD-10-CM code set (in effect since 1 October 2026), when to move to M17 osteoarthritis, S83 injury or M23 internal derangement codes, how 7th characters work for injuries, and worked examples for clinic, orthopedic and imaging claims.
Key Takeaways
- M25.56 is a subcategory header and is not billable. Report M25.561 (right), M25.562 (left) or, rarely, M25.569 (unspecified knee).
- There is no bilateral knee pain code. For pain in both knees, report M25.561 and M25.562, not M25.569.
- Use the symptom code only when no definitive diagnosis is documented. Confirmed osteoarthritis goes to M17, and the pain code is dropped.
- Acute knee injuries are coded from Chapter 19 (S80 to S89) and need a 7th character: A, D or S.
- Old meniscus tears and chronic derangements are coded from M23, while a current meniscus tear is S83.2-.
Knee Pain ICD-10 Codes (M25.56-) for FY2027
Knee pain sits in category M25, Other joint disorder, not elsewhere classified, under subcategory M25.5, Pain in joint. The 6th character carries laterality.
| Code | Official title | Billable? | Use when |
|---|---|---|---|
| M25.56 | Pain in knee | No, subcategory | Never report alone |
| M25.561 | Pain in right knee | Yes | Right knee pain, no definitive diagnosis |
| M25.562 | Pain in left knee | Yes | Left knee pain, no definitive diagnosis |
| M25.569 | Pain in unspecified knee | Yes | Side truly not documented and cannot be obtained |
Bilateral knee pain: report two codes
Section I.B.13 of the ICD-10-CM Official Guidelines says that when a condition is bilateral and no bilateral code exists, you assign separate codes for the left and right side. The M25.56- subcategory has no bilateral option, so pain in both knees is M25.561 plus M25.562. The guidelines also say an unspecified-side code should rarely be needed, because laterality is usually in the record.
Do not use M25.569 for bilateral knee pain. M25.569 means the side is unknown, not that both sides hurt. Payers that edit for laterality may deny an imaging or injection line linked to it.
Symptom Code or Definitive Diagnosis?
For outpatient encounters, Section IV of the guidelines tells you to code to the highest degree of certainty. If the provider has not established a diagnosis, the symptom (M25.56-) is correct. Diagnoses documented as probable, suspected or rule out are not coded in outpatient settings.
Once the diagnosis is confirmed, Section I.B.5 applies: symptoms routinely associated with a disease are not coded separately. Knee pain is integral to knee osteoarthritis or a meniscus tear, so the M25.56- code comes off the claim.
Acute vs chronic musculoskeletal conditions. The Chapter 13 guidelines direct current, acute injuries to Chapter 19 injury codes, while chronic or recurrent conditions and conditions resulting from a healed injury are usually coded in Chapter 13. This is the rule that separates S83 tears from M23 derangements.
ICD-10-CM has no separate acute or chronic version of M25.56-. If the provider documents chronic knee pain and the visit is for pain management, review the G89 guidelines: G89.29, Other chronic pain, may be sequenced first with M25.561 or M25.562 added for the site. If the plan includes nerve ablation, note that genicular nerve destruction has its own code (64624); other peripheral nerves are reported with CPT 64640.
Knee Osteoarthritis Codes (M17)
Unlike knee pain, the osteoarthritis category does have bilateral codes. Choose by type (primary, post-traumatic, secondary) and by side.
| Code | Official title | Billable? |
|---|---|---|
| M17.0 | Bilateral primary osteoarthritis of knee | Yes |
| M17.11 | Unilateral primary osteoarthritis, right knee | Yes |
| M17.12 | Unilateral primary osteoarthritis, left knee | Yes |
| M17.10 | Unilateral primary osteoarthritis, unspecified knee | Yes |
| M17.2 | Bilateral post-traumatic osteoarthritis of knee | Yes |
| M17.31 / M17.32 | Unilateral post-traumatic osteoarthritis, right knee / left knee | Yes |
| M17.4 | Other bilateral secondary osteoarthritis of knee | Yes |
| M17.5 | Other unilateral secondary osteoarthritis of knee | Yes |
| M17.9 | Osteoarthritis of knee, unspecified | Yes |
M17, M17.1 and M17.3 are headers and cannot be billed. Pain management groups treating knee OA with injections or ablation can see our pain management billing services.
Knee Injury Codes (S80 to S89) and 7th Characters
Every code in the injury chapter needs a 7th character. Where a code has fewer than six characters, the placeholder X fills the gap, as in S83.91XA.
| 7th character | Meaning | Typical knee use |
|---|---|---|
| A | Initial encounter | Each encounter while the patient receives active treatment, such as evaluation, imaging to diagnose and surgery |
| D | Subsequent encounter | Encounters after active treatment, during routine healing and recovery, such as a post-op recheck |
| S | Sequela | A late effect of the injury, coded with the residual condition |
| Code | Official title |
|---|---|
| S83.241A | Other tear of medial meniscus, current injury, right knee, initial encounter |
| S83.242A | Other tear of medial meniscus, current injury, left knee, initial encounter |
| S83.511A | Sprain of anterior cruciate ligament of right knee, initial encounter |
| S83.512A | Sprain of anterior cruciate ligament of left knee, initial encounter |
| S83.91XA | Sprain of unspecified site of right knee, initial encounter |
| S80.01XA | Contusion of right knee, initial encounter |
External cause codes, such as W01.0XXA, Fall on same level from slipping, tripping and stumbling without subsequent striking against object, initial encounter, add context. Report them when your payer or state reporting rules require them.
Internal Derangement Codes (M23) vs Current Tears (S83)
A meniscus tear can be coded two ways. A current tear from a recent injury is S83.2-. A tear documented as old, degenerative or due to an old injury is M23.2-, Derangement of meniscus due to old tear or injury, which specifies the meniscus, the horn and the knee.
Example code. M23.221, Derangement of posterior horn of medial meniscus due to old tear or injury, right knee. The 4- and 5-character levels (M23.2, M23.22) are headers, so always carry the code to its 6th character.
Knee Codes Often Confused With M25.56-
| Code | Official title | Use instead of knee pain when |
|---|---|---|
| M17.11 | Unilateral primary osteoarthritis, right knee | Imaging or exam confirms right knee OA |
| S83.241A | Other tear of medial meniscus, current injury, right knee, initial encounter | A recent injury caused a medial meniscus tear |
| M23.221 | Derangement of posterior horn of medial meniscus due to old tear or injury, right knee | The tear is documented as old |
| M22.2X1 | Patellofemoral disorders, right knee | The provider diagnoses a patellofemoral disorder |
| M76.51 | Patellar tendinitis, right knee | Patellar tendinitis is documented |
| M25.461 | Effusion, right knee | Effusion is documented and not explained by a confirmed diagnosis |
Pain After Knee Surgery or Replacement
Routine or expected pain right after surgery is not coded separately. When the provider links pain to a knee prosthesis, code T84.84XA, Pain due to internal orthopedic prosthetic devices, implants and grafts, initial encounter, with a G89 code to show acute or chronic pain, and Z96.651, Presence of right artificial knee joint, when appropriate. Postprocedural pain not linked to a device complication may be G89.18, Other acute postprocedural pain.
Worked Examples
Example 1, primary care. Right knee pain for three weeks, no injury, X-ray ordered, no diagnosis yet. Code M25.561.
Example 2, both knees. Pain in both knees, cause not yet established. Code M25.561 and M25.562.
Example 3, orthopedics. X-ray shows primary osteoarthritis of the left knee, and the provider documents it. Code M17.12 only. The pain code is not added.
Example 4, imaging. A twisting injury playing soccer; the MRI report and the treating provider confirm a medial meniscus tear of the right knee. The diagnosis is S83.241A, and the MRI line is 73721-RT.
How to Code Knee Pain Step by Step
- Confirm the side. Find right, left or both in the note. Query the provider if it is missing.
- Look for a definitive diagnosis. If OA, a tear, a sprain or tendinitis is confirmed, code it and drop M25.56-.
- Decide acute or chronic. Current injuries go to S80 to S89; old or recurrent conditions go to Chapter 13, such as M23.
- Add the 7th character. For injury codes, choose A, D or S based on the stage of care, using X placeholders where needed.
- Match the procedure. Make sure the diagnosis side matches the RT or LT modifier on each procedure line.
Laterality, Imaging and Denials
Doctors must specify the side in their examination notes, and imaging should label the knee clearly. The imaging claim needs the matching RT or LT modifier (see our CPT 73721 knee MRI billing guide). A modifier that conflicts with the procedure often returns as a CO-4 denial, and a diagnosis that does not support the service as a CO-11 denial.
Therapy practices should pair the most specific knee diagnosis with correctly timed units; our 8-minute rule guide and physical therapy billing audit checklist cover the procedure side.
- Never bill M25.56, M17, M17.1, M17.3, M23.2 or a 6-character injury code without its 7th character.
- Replace the symptom code as soon as a definitive diagnosis is documented.
- Check that each diagnosis pointer matches the side of the procedure it supports.
- Verify codes against the FY2027 set for dates of service on or after 1 October 2026.
For a refresher on how diagnosis and procedure codes fit together, see understanding CPT, ICD-10 and HCPCS codes.
Tired of laterality and specificity denials on knee claims? Steady Medical Billing’s medical coding team checks every diagnosis against the record and the procedure line before claims go out. Orthopedic groups can also see our orthopedic billing services.
Frequently Asked Questions
What is the ICD-10 code for right knee pain?
M25.561, Pain in right knee. Left knee pain is M25.562, and M25.569 is used only when the side is not documented.
What is the ICD-10 code for bilateral knee pain?
There is no bilateral knee pain code. Report both M25.561 and M25.562. Do not use M25.569, which means the side is unspecified.
Is M25.56 a billable code?
No. M25.56 is a subcategory header. A 6th character for laterality is required: M25.561, M25.562 or M25.569.
Can I code knee pain with knee osteoarthritis?
Generally no. Pain is routinely associated with osteoarthritis, so once M17 osteoarthritis is confirmed, the M25.56- pain code is not reported separately.
What 7th character do knee injury codes need?
Use A while the patient receives active treatment, D for routine care during healing after active treatment, and S for sequelae. Add the placeholder X where the code is shorter than six characters, as in S83.91XA.
