ICD-10 Code for Knee Pain: M25.561, M25.562, and Bilateral Coding Guide (2026)

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. M25.56 is the non-billable parent code, so coders select a laterality-specific child code on every claim.

Pick the wrong one and the claim doesn't just sit there. It comes back. Knee pain ICD-10 errors are one of the quietest causes of orthopedic revenue loss, because the codes look simple and the laterality rule gets skipped.

This guide walks through right, left, bilateral, unspecified, and chronic coding, plus the documentation that keeps these claims clean in 2026.

What Is the ICD-10 Code for Knee Pain?

Knee pain falls under M25.56 (Pain in knee) in the ICD-10-CM musculoskeletal chapter, with three billable child codes: M25.561 for the right knee, M25.562 for the left knee, and M25.569 for an unspecified knee. Bilateral knee pain requires both M25.561 and M25.562.

Here's the structure. M25.56 sits as a subcategory under category M25 (Other and unspecified joint disorders) in Chapter 13, the musculoskeletal chapter of ICD-10-CM. That parent code isn't billable on its own. It's missing the sixth character that tells the payer which knee you're talking about.

That sixth character is the whole point. Choosing a knee pain ICD-10 code comes down to one detail: laterality. Without it, the claim fails the specificity test and the payer kicks it back.

Here are the billable codes:

• M25.561: Pain in right knee. Use when the record documents right-sided knee pain and no underlying diagnosis is confirmed.
• M25.562: Pain in left knee. Use when the record documents left-sided knee pain and no underlying diagnosis is confirmed.
• M25.569: Pain in unspecified knee. Use only when laterality is genuinely not documented.
• Bilateral knee pain: report M25.561 and M25.562 together. There's no single bilateral knee pain code.

That last point trips up a lot of billers, so it's worth saying plainly. When both knees hurt, you report two codes on the same claim. No combined code exists, and waiting for one won't help.

Specificity isn't a formatting preference. The CMS Official Guidelines require coding to the highest level of specificity the record supports. Every knee pain ICD-10 claim needs that sixth character to be billable, and skipping it is the fastest way to a denial.

If you handle other joint symptoms, the same logic shows up in our back pain ICD-10 coding guide. For the bigger picture on how the code set is built and where it's headed, see our breakdown of ICD-10 vs ICD-11.

M25.561: ICD-10 Code for Right Knee Pain

M25.561 is the ICD-10-CM code for pain in the right knee. It's a billable symptom code for both acute and chronic right knee pain, used when no underlying diagnosis like osteoarthritis or a meniscus tear has been confirmed by the provider.

There's no separate acute knee pain ICD-10 code in the M25.56 family. On a knee pain ICD-10 claim, duration doesn't change the code, but the documented side always does. That surprises people who go looking for an acute-specific option.

Here's where it gets practical. If the note documents an injury mechanism, a fall, a twist, or a direct impact, M25.561 usually isn't the right code anymore.

Acute right knee pain ICD-10 coding follows one rule: no injury mechanism points to M25.561, but a documented mechanism points to an S-code from the S83 or S80 family instead. That switch matters, because an injury code supports the imaging and the workup a symptom code can't.

Documentation drives all of it. The right knee pain ICD-10 code stays valid only when the chart actually says "right," and it should pair with the correct office visit or therapy CPT on the claim.

The ICD-10 code for right knee pain is M25.561, full stop, but the diagnosis pointer has to link to the right service line.

One more rule. Stop using M25.561 the moment a structural diagnosis is confirmed. Once osteoarthritis or a tear is documented, you upgrade to the specific code and drop the symptom code.

You can verify the official descriptor for M25.561 anytime. Orthopedic and therapy practices that pair it with the wrong visit level see preventable denials, which is why clean physical therapy CPT codes and accurate use of CPT code 97140 for manual therapy matter as much as the diagnosis itself.

M25.562: ICD-10 Code for Left Knee Pain

M25.562 is the ICD-10-CM code for pain in the left knee. It's a billable diagnosis code used when a patient presents with left knee pain and the provider hasn't established a definitive cause such as osteoarthritis, a ligament injury, or a meniscus tear.

The same knee pain ICD-10 laterality rule applies on the left, just mirrored. M25.562 works for both acute and chronic presentations, and there's no separate code for how long the pain has lasted. On any left knee pain ICD-10 claim, documenting the side is what makes the code hold.

Pairing is where claims live or die. The left knee pain ICD-10 code should sit on the claim next to the right office visit or therapy code, with the diagnosis pointer linked correctly.

A new-patient evaluation carrying this diagnosis often runs through CPT code 99203 for a new patient visit, while therapy sessions might bill CPT code 97530 for therapeutic activities. M25.562 is only as clean as the service line it's attached to.

Now the upgrade rule, same as the right side. Once the provider confirms a definitive left knee diagnosis, M25.562 comes off the claim and the specific code takes over. The symptom code is a placeholder, not a permanent answer.

Here's the error I see most on left-side claims. The chart clearly says "left," but the claim goes out with M25.569, the unspecified code. That's a specificity problem, and it's avoidable.

When the side is documented, the ICD-10 code for left knee pain is M25.562, not the unspecified option. Defaulting to M25.569 when laterality is right there in the note is the habit that draws payer scrutiny, and we'll get into why next.

You can confirm the descriptor for M25.562 directly. Left knee pain ICD-10 claims are high volume in orthopedic and therapy billing, so a small habit fix here protects a lot of revenue.

Bilateral Knee Pain ICD-10: Why You Report Two Codes

Bilateral knee pain has no single ICD-10-CM code. When a patient has pain in both knees, coders report M25.561 for the right knee and M25.562 for the left knee as two separate diagnosis codes on the same claim, because no combined bilateral knee pain code exists.

Bilateral is where the knee pain ICD-10 rules trip people up. There's no shortcut for both knees. You list two codes, every time, and the claim carries both. The right knee pain ICD-10 code and the left each stand on their own line.

Here's the part most coding guides skip: the claim mechanics. On the CMS-1500, both M25.561 and M25.562 go in Field 21 as separate diagnosis codes, and each one gets its own diagnosis pointer linked to the relevant service line.

Miss the pointer linkage and the payer can't tell which service maps to which knee. Bilateral knee pain ICD-10 claims fall apart at exactly that step.

Patients and front desk staff rarely say "bilateral." They say both knees hurt. So when you see "left and right knee pain," "b/l knee pain," or "pain in both knees" in the note, that all maps to the same pair: M25.561 and M25.562 together. The wording changes, the two-code rule doesn't.

There's a name for this. Reporting two codes to capture one clinical picture is called multiple coding under ICD-10-CM Official Guidelines Section I.B.9. It isn't a workaround. It's the correct method when no combined code exists for the condition.

Now the correction that catches a lot of teams. M25.569 is not the bilateral code. Using the unspecified code for documented bilateral pain is a specificity error, because the chart clearly names both sides. Bilateral knee pain ICD-10 coding means two specific laterality codes, not one unspecified code standing in for both.

The official descriptors live in the CMS ICD-10 code set if you want to confirm them. When bilateral claims get denied for coding mismatches, they need systematic follow-up before the timely filing window closes, and that's where structured AR follow-up services keep two-code claims from aging into write-offs.

M25.569: Unspecified Knee Pain and Audit Risk

M25.569 is the ICD-10-CM code for pain in an unspecified knee. It's billable, but use it only when the medical record genuinely doesn't document which knee is affected, because submitting M25.569 when laterality is known creates a specificity error that payers frequently deny.

M25.569 is the one knee pain ICD-10 code that draws audit attention. The unspecified knee pain ICD-10 code is M25.569, and it has exactly one correct use case: the chart truly doesn't say which knee. That's rare. Most of the time, the side is sitting right there in the note.

Here's where it goes wrong. The provider documents "left knee," but the claim goes out with M25.569 anyway, usually because of a template default or a rushed charge entry. An unspecified knee pain ICD-10 claim only holds up when laterality is genuinely missing, not when someone skipped a step.

Some systems and searches show it as M25 569 without the period. Whether you see M25 569 or M25.569 on a worklist, it's the same unspecified code with the same documentation rule behind it.

The consequence isn't theoretical. Submitting an unspecified code when the side is known is a specificity violation under Official Guidelines Section I.A.1, and it creates a documentation-coding mismatch the payer can flag. That mismatch is what turns a routine claim into a record request.

This is the audit exposure worth knowing. CMS Targeted Probe and Educate review targets musculoskeletal claims, and the 2026 OIG compliance focus includes laterality specificity. A pattern of unspecified codes on charts that clearly name the side is the kind of signal that invites a closer look. You can review the OIG compliance guidance directly.

The fix takes one habit. Query the provider for laterality before submission instead of defaulting to M25.569. Confirming the side at intake, the same way you'd handle insurance verification and authorization, closes the gap before the claim goes out.

Practices seeing repeated unspecified-code denials usually have a template problem, not a coding problem. Structured denial management services catch the pattern before it spreads across a month of claims.

When to Switch From Knee Pain Codes: Osteoarthritis (M17) and Injury (S83)

Knee pain codes are symptom codes. Once a provider confirms an underlying cause, the specific diagnosis replaces M25.56x. Osteoarthritis moves coding to the M17 family, and a documented injury moves it to the S83 family, per ICD-10-CM Official Guidelines on symptom coding.

Symptom codes have a shelf life. Official Guidelines Section I.B.5 says you use them before a definitive diagnosis is established, not after. Once a real diagnosis lands, the knee pain ICD-10 code isn't your code anymore, and keeping it on the claim is undercoding.

Osteoarthritis of the Knee: The M17 Codes

Confirmed knee OA codes to the M17 family with laterality, and osteoarthritis knee ICD-10 selection turns on two documented details: which side, and whether the arthritis is primary or post-traumatic. Here are the working codes:

• M17.11: Unilateral primary osteoarthritis, right knee.
• M17.12: Unilateral primary osteoarthritis, left knee.
• M17.0: Bilateral primary osteoarthritis of knee.
• M17.31: Unilateral post-traumatic osteoarthritis, right knee.
• M17.32: Unilateral post-traumatic osteoarthritis, left knee.
• M17.9: Osteoarthritis of knee, unspecified.

Pick the M17 code that matches both the side and the type. Osteoarthritis knee ICD-10 coding rewards specificity the same way the symptom codes do, so primary versus post-traumatic has to come from the documentation, not a guess.

Knee Injuries: When to Use the S83 Codes

A documented injury mechanism changes everything. When the note records a fall, a twist, or an impact, coding moves to the S83 family for sprains, tears, and dislocations.

S83 codes need a seventh character: A for the initial encounter, D for subsequent, and S for sequela. S-codes justify the imaging and the surgical workup a symptom code can't support.

Here's the quick decision rule:

Keep your code set current too. The April 1, 2026 ICD-10-CM release is the active set, and the full osteoarthritis range sits in the M15 to M19 osteoarthritis codes.

Accurate osteoarthritis knee ICD-10 coding also protects the higher reimbursement a confirmed diagnosis supports. Practices that keep billing M25.56x after a confirmed OA or injury diagnosis are undercoding and inviting denials, and clean outsourced medical billing services build that upgrade discipline into charge entry.

The diagnosis also drives the visit level, whether that's CPT code 99205 for a high-complexity new patient visit, the physical therapy CPT codes for rehab, or occupational therapy CPT codes for functional recovery.

Chronic Knee Pain ICD-10: Coding G89.29 With Knee Codes

Chronic knee pain has no dedicated ICD-10-CM code. Coders report it by pairing the laterality code, M25.561 or M25.562, with G89.29 (other chronic pain) when the provider documents chronicity. Sequencing depends on whether the encounter treats the knee condition or focuses on pain management.

Chronic cases need more than a standard knee pain ICD-10 code. You build the picture with two codes, and chronic knee pain ICD-10 coding lives or dies on sequencing. Get the order wrong and the claim can misrepresent the reason for the visit.

How to Sequence G89.29 and the Knee Code

Official Guidelines Section I.C.6 gives you the order, and it changes with the visit. Clean chronic knee pain ICD-10 coding comes down to two things: documented chronicity and correct sequence. Three scenarios cover almost everything you'll see.

When the visit treats the knee condition itself, sequence the knee code first and the chronic pain code second: M25.561 or M25.562, then G89.29. When the encounter is a dedicated pain-management visit, flip it: G89.29 first, then the knee code.

For chronic bilateral knee pain ICD-10 coding, you report all three: M25.561, M25.562, and G89.29, with the sequence driven by why the patient came in.

There's a guardrail. Don't assign G89.29 unless the provider actually documents the pain as chronic. Chronic and acute knee pain ICD-10 coding aren't interchangeable, and a code for chronic pain on an acute presentation is a documentation mismatch waiting to be flagged.

Chronic Bilateral and Chronic Left Knee Pain

Two laterality pairings come up constantly. Chronic right knee pain is M25.561 plus G89.29. Chronic left knee pain ICD-10 coding is M25.562 plus G89.29. Same logic, different side, with sequencing still tied to the encounter's purpose.

The same G89 sequencing rules apply across joint pain codes, not just the knee, which is why our left shoulder pain ICD-10 code M25.512 guide follows the same pattern. You can confirm the knee descriptors against the AAPC code reference for M25.561.

Chronic follow-up visits that carry the chronic pain pairing often bill CPT code 99212 for an established patient visit. Because chronic knee conditions drive advanced imaging and extended therapy, they trigger the prior authorization services requirements that stall claims when nobody's tracking them.

Associated Knee Codes: Effusion, Hemarthrosis, and Stiffness

Three code families are billed alongside knee pain when the provider documents specific findings: M25.46x for effusion, M25.06x for hemarthrosis, and M25.66x for stiffness. Each follows the same right, left, and unspecified laterality pattern as the M25.56x knee pain codes.

These show up more than you'd expect on orthopedic claims, and they're easy to miss. Here are the three families:

• Effusion: M25.461 (right), M25.462 (left), M25.469 (unspecified). Common on knee claims when joint swelling is documented.
• Hemarthrosis: M25.061 (right), M25.062 (left), M25.069 (unspecified). Shows up post-injury or after a procedure.
• Stiffness: M25.661 (right), M25.662 (left), M25.669 (unspecified). A secondary code when range-of-motion limitation is documented separately.

Match the finding to the documentation. Effusion pairs with a pain code when the note records swelling, hemarthrosis fits a bleed into the joint, and stiffness codes a separate functional limitation. Therapy for stiffness and range of motion often bills CPT code 97112 for neuromuscular reeducation or CPT code 97110 for therapeutic exercises.

One stability note worth keeping. The ICD-10 Coordination and Maintenance Committee met in March 2026 and proposed no changes to the M25.56x knee pain family, so these codes hold through the next cycle. You can review the ICD-10 Coordination and Maintenance Committee materials for the full agenda.

Knee Pain Coding and Your Revenue Cycle

Knee pain coding errors are a revenue problem, not just a compliance one. Unspecified-code overuse, missing laterality, and undercoding after a confirmed diagnosis each generate preventable denials. For orthopedic and therapy practices, clean knee pain coding directly affects how fast claims get paid.

The numbers back this up. Coding errors account for roughly 35% of claim denials, and initial denial rates climbed to 11.8% in 2024 from 10.2% the year before. Every denied claim is rework, and rework is time your staff doesn't have.

The fix isn't complicated, it's just consistent. Build in certified coding review, verify laterality before submission, and upgrade the code as the diagnosis evolves. These three habits stop most knee pain denials before they start.

Here's where MedSole RCM fits. Orthopedic, physical therapy, occupational therapy, and pain management practices billing M25.561, M25.562, M17.x, and S83.x codes that want a full-service billing partner should know the numbers.

MedSole RCM charges 2.99% of collections for billing, well below the 7% to 10% typical of specialty orthopedic billing firms. Credentialing runs $99 per payer, with a 99% clean claim rate, coverage across 900-plus payer networks in all 50 states, and more than 4,000 providers credentialed.

That pricing pairs with real depth on the credentialing side, which you can see in our breakdown of the best credentialing services for healthcare providers and our provider enrollment and credentialing services. If knee pain claims are leaking revenue and you want a second set of eyes, our outsourced medical billing services team can walk through your denials with you.

Knee Pain ICD-10 Coding: Frequently Asked Questions

What is the ICD-10 code for knee pain?

The ICD-10 code for knee pain is M25.561 for the right knee, M25.562 for the left knee, and M25.569 for an unspecified knee. M25.56 is the parent code, not billable on its own. Always pick a laterality-specific child code. Our abdominal pain ICD-10 coding guide follows the same symptom-coding approach.

Is M25.56 a billable code?

No, M25.56 isn't billable. It's the parent code for pain in the knee, and it's missing the sixth character that identifies laterality. A clean claim needs M25.561 for the right knee, M25.562 for the left, or M25.569 when the side isn't documented. Submit M25.56 alone and the payer rejects it for lack of specificity.

How do you code bilateral knee pain?

Bilateral knee pain needs both M25.561 and M25.562 on the same claim. There's no single bilateral code, so you report both, each linked to its own service line. When both knees are documented, two codes is correct, not a workaround. Clean two-code claims are part of what solid medical billing and credentialing services protect.

What is the ICD-10 code for chronic knee pain?

Chronic knee pain has no dedicated code. You pair the laterality code, M25.561 or M25.562, with G89.29 for other chronic pain, but only when the provider documents it as chronic. Sequencing depends on the visit: knee code first for treatment, G89.29 first for pain management. Confirm chronic-care coverage with upfront verification of benefits.

Does anyone still use ICD-9 for knee pain?

No, ICD-9 was retired for HIPAA claims on October 1, 2015, and no payer accepts it now. The legacy code 719.46 for knee pain was replaced by the ICD-10 codes M25.561, M25.562, and M25.569. Seeing old codes in a system is a mapping issue worth fixing fast, since stale codes drive denial management headaches.

What's the difference between a knee pain code and an osteoarthritis code?

A knee pain code is a symptom code, used before a diagnosis is confirmed. The M17 osteoarthritis codes are used once the provider documents OA as the cause. Put simply, M25.561 says the knee hurts, and M17.11 says why. Smaller offices often lean on medical billing services for small practices to keep that upgrade discipline consistent.

Key Takeaways for 2026 Knee Pain Coding

Knee pain coding comes down to specificity: M25.561 for the right knee, M25.562 for the left, both codes for bilateral, and M25.569 only when the side genuinely isn't documented.

Keep these rules close:

• Use the laterality codes over M25.569 whenever the side is documented.
• Upgrade to an M17 or S83 code once a diagnosis is confirmed.
• Pair G89.29 for chronic pain, with sequencing driven by the visit.
• Confirm your code set reflects the April 1, 2026 update.

When you're ready, a quick billing or coding review will show where knee pain claims are leaking revenue. MedSole RCM runs orthopedic and therapy billing at 2.99% of collections, with credentialing at $99 per payer, through our outsourced medical billing services.