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The ICD-10 code for right knee pain is M25.561 (Pain in right knee). Use M25.562 for left knee pain and M25.569 only when the side isn’t documented. There’s no single code for bilateral knee pain: report M25.561 and M25.562 together. When the cause of the pain is known, such as osteoarthritis (M17.11) or a sprain (S83.91XA), code the cause instead of M25.561.
Knee pain is one of the most common complaints in primary care, orthopedics, sports medicine and physical therapy, and also one of the most commonly miscoded. At AffinityCore, our certified coders see the same knee errors every week: missing laterality, symptom codes used alongside a confirmed diagnosis, and injury codes with the wrong 7th character. This guide gives you every right knee ICD-10 code you’re likely to need, with the rules for choosing between them.
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What Is ICD-10 Code M25.561?
M25.561 is the ICD-10-CM diagnosis code for pain in the right knee. It sits in category M25.5 (Pain in joint), under M25 (Other joint disorder, not elsewhere classified). It’s a billable, specific code, valid in the 2027 ICD-10-CM code set effective October 1, 2026.
Use M25.561 when the provider documents right knee pain and no definitive cause has been established, for example at a first visit before imaging, or when workup is still in progress.
Knee pain ICD-10 codes (M25.56-)
| Code | Description | Use it for |
| M25.561 | Pain in right knee | Right knee pain, cause not yet determined |
| M25.562 | Pain in left knee | Left knee pain, cause not yet determined |
| M25.569 | Pain in unspecified knee | Side not documented; avoid, because payers often deny it |
| M25.56 | Pain in knee | Not billable; needs a 6th character for laterality |
| M25.50 | Pain in unspecified joint | Not specific enough for knee pain |
What is the ICD-10 code for bilateral knee pain?
ICD-10-CM has no bilateral code for knee pain. For pain in both knees, report M25.561 and M25.562 together. Don’t use M25.569 for bilateral pain: it means the side is unknown, not both.
Chronic and Acute Right Knee Pain ICD-10 Codes
ICD-10-CM has no single code for “chronic right knee pain” or “acute right knee pain.” Combine M25.561 with a code from category G89 (Pain, not elsewhere classified) when the provider documents the pain type.
| Scenario | Codes | Sequencing rule |
| Chronic right knee pain, visit for the knee condition | M25.561 + G89.29 (other chronic pain) | M25.561 first |
| Chronic right knee pain, visit for pain management | G89.29 + M25.561 | G89.29 first |
| Chronic pain of both knees | G89.29 + M25.561 + M25.562 | Same rules as above |
| Acute right knee pain after an injury, pain control is the focus | G89.11 (acute pain due to trauma) + the injury code | G89.11 first |
| Acute right knee pain, no trauma, no pain management focus | M25.561 alone | G89 isn’t needed |
| Pain after knee surgery | G89.18 (acute) or G89.28 (chronic) postprocedural pain | Only when documented as postprocedural |
Only assign a G89 code when the provider uses the words acute, chronic or postprocedural. Never infer them from how long the pain has lasted.
When Not to Use M25.561: Right Knee Osteoarthritis and Arthritis
M25.561 is a symptom code. ICD-10-CM guidelines say signs and symptoms that are routinely part of a confirmed diagnosis shouldn’t be coded separately. Once X-rays or an exam confirm osteoarthritis, the arthritis code replaces M25.561.
Right knee osteoarthritis ICD-10 (M17.11)
M17.11, Unilateral primary osteoarthritis, right knee, is the code for osteoarthritis of the right knee. Degenerative joint disease (DJD) is the same condition in ICD-10-CM, so DJD of the right knee also codes to M17.11.
| Diagnosis | ICD-10-CM code |
| Primary osteoarthritis / DJD, right knee | M17.11 |
| Primary osteoarthritis, left knee | M17.12 |
| Bilateral primary osteoarthritis of knees | M17.0 |
| Post-traumatic osteoarthritis, right knee | M17.31 |
| Osteoarthritis of knee, unspecified | M17.9 (avoid if side and type are known) |
| Rheumatoid arthritis, right knee (other specified) | M06.861 |
| Idiopathic gout, right knee | M10.061 |
| Chondromalacia patellae, right knee | M22.41 |
| Patellofemoral disorder, right knee | M22.2X1 |
Common error: reporting both M17.11 and M25.561 on the same claim. Knee pain is part of knee osteoarthritis, so M25.561 is redundant and can trigger edits. Only report it alongside another diagnosis when the pain is clearly unrelated to that condition.
Right Knee Injury, Sprain and Strain ICD-10 Codes
Knee injuries are coded from Chapter 19 (S80–S89, injuries to the knee and lower leg), not from the M25 pain codes. Every injury code needs a 7th character:
- A: initial encounter, while the patient is receiving active treatment
- D: subsequent encounter, routine healing or follow-up care
- S: sequela, a late effect of the injury
| Injury | ICD-10-CM code (initial encounter) |
| Sprain of right knee, unspecified site | S83.91XA |
| Sprain of medial collateral ligament (MCL), right knee | S83.411A |
| Sprain of lateral collateral ligament (LCL), right knee | S83.421A |
| Sprain of anterior cruciate ligament (ACL), right knee | S83.511A |
| Sprain of posterior cruciate ligament (PCL), right knee | S83.521A |
| Strain of muscle/tendon at lower leg level, right (“right knee strain”) | S86.911A |
| Strain of muscle/tendon at thigh level, right | S76.911A |
| Tear of medial meniscus, current injury, right knee | S83.241A (other tear) |
| Tear of lateral meniscus, current injury, right knee | S83.281A (other tear) |
| Contusion of right knee | S80.01XA |
| Dislocation of right knee, unspecified | S83.104A |
| Dislocation of right patella, unspecified | S83.004A |
| Injury of right knee / lower leg, unspecified | S89.91XA |
Right knee sprain vs strain: which code?
A sprain injures a ligament (MCL, LCL, ACL, PCL), so it codes to S83.-. A strain injures a muscle or tendon, so it codes to the muscle’s level: S86.- for lower leg muscles and tendons, or S76.- for thigh muscles such as the quadriceps. Many notes say “knee strain” when they mean a ligament sprain, so query the provider if the tissue isn’t clear.
For bilateral knee sprains or strains, report the right and left codes separately (for example S83.91XA + S83.92XA). Optional external cause codes (V00–Y99) can add how and where the injury happened, which helps with liability and workers’ compensation claims.
Right Knee Swelling, Effusion, Instability and Other ICD-10 Codes
| Condition | ICD-10-CM code | Note |
| Effusion of right knee | M25.461 | Also used for right knee swelling: the index sends “swelling, joint” to effusion |
| Effusion of left knee | M25.462 | Bilateral: report M25.461 + M25.462 |
| Stiffness of right knee, NEC | M25.661 | |
| Other instability, right knee | M25.361 | Instability not due to old ligament injury |
| Chronic instability of right knee | M23.51 | Chronic instability, e.g. after old ligament injury |
| Internal derangement of right knee, unspecified | M23.91 | Use a specific M23 code once the derangement is identified |
| Derangement of meniscus due to old tear, right knee | M23.2- | For degenerative or old tears, not current injuries |
| Infection of right knee prosthesis | T84.53XA | Infection due to internal right knee prosthesis |
| Septic (pyogenic) arthritis of right knee | M00.- by organism | e.g. M00.061 staphylococcal arthritis, right knee |
Swelling plus pain: if the provider documents both right knee pain and swelling without a diagnosis, report M25.561 and M25.461. If a definitive cause such as osteoarthritis or a meniscus tear is confirmed, code only that condition.
Related CPT Codes: Right Knee X-Ray, Arthroscopy and Arthroplasty
ICD-10-CM codes say why the patient was seen. CPT codes say what was done. These are the procedure codes most often paired with right knee diagnoses.
| Service | CPT code | Note |
| X-ray knee, 1 or 2 views | 73560 | Add modifier RT for the right knee |
| X-ray knee, 3 views | 73562 | |
| X-ray knee, complete, 4 or more views | 73564 | |
| X-ray both knees, standing AP | 73565 | Bilateral weight-bearing film |
| MRI knee without contrast | 73721 | Often needs prior authorization |
| Diagnostic knee arthroscopy | 29870 | Bundled into surgical arthroscopy |
| Arthroscopic meniscectomy, medial OR lateral | 29881 | |
| Arthroscopic meniscectomy, medial AND lateral | 29880 | |
| Arthroscopic ACL reconstruction | 29888 | |
| Total knee arthroplasty | 27447 | Inpatient: ICD-10-PCS 0SRC- (replacement, right knee joint) |
| Unicompartmental knee arthroplasty | 27446 |
ICD-10 codes after right knee arthroplasty
After a total knee replacement, report Z96.651 (Presence of right artificial knee joint) on later encounters. For routine post-op aftercare, sequence Z47.1 (Aftercare following joint replacement surgery) first, then Z96.651. A complication, such as an infected right knee prosthesis (T84.53XA), replaces the aftercare code.
For arthroscopy, the ICD-10 code is the reason for the scope, such as a meniscus tear (S83.2- or M23.2-), not a separate “arthroscopy” diagnosis.
Common Knee Pain Coding Errors (and Denials They Cause)
| Error | Result | Fix |
| M25.569 when the side is documented | Specificity denial | Use M25.561 or M25.562 |
| M25.569 for bilateral knee pain | Inaccurate claim | Report M25.561 + M25.562 |
| M25.561 with M17.11 on the same claim | Redundant symptom code; edits | Code only the confirmed diagnosis |
| Injury code with no 7th character | Claim rejection | Add A, D or S |
| “A” used for every visit, including PT follow-ups | Audit risk | Use D for routine healing and follow-up care |
| Knee x-ray without RT/LT | Payer edits on laterality | Add RT or LT to 73560–73564 |
| G89.29 added without “chronic” documented | Unsupported code | Assign G89 only when the provider documents it |
| M25.561 kept after imaging confirms a cause | Medical necessity mismatch for procedures | Update to the confirmed diagnosis |
The last error is especially costly for PT and orthopedic practices. An MRI, injection or arthroscopy billed with only M25.561 often fails medical necessity checks, while the same service billed with M17.11 or a meniscus tear code gets paid.
How AffinityCore Helps Orthopedic and PT Practices Code Knee Claims Right
AffinityCore gives orthopedic, sports medicine, primary care and physical therapy practices certified coders who code knee encounters to the highest supported specificity on the first pass.
- Certified medical coding: correct laterality, 7th characters and symptom-vs-diagnosis sequencing on every knee claim.
- Orthopedic billing: arthroscopy, arthroplasty, injections and imaging, with modifiers, global periods and prior authorizations handled.
- Physical therapy billing: knee rehab claims coded with the right diagnosis and 8-minute rule units.
- Denial management: specificity and medical necessity denials are corrected and resubmitted quickly.
Getting knee claims denied for specificity or medical necessity? Request a free coding review from AffinityCore
Frequently Asked Questions
What is the ICD-10 code for right knee pain?
The ICD-10 code for right knee pain is M25.561, Pain in right knee. It’s billable and is used when the cause of the pain hasn’t been determined. Left knee pain is M25.562.
What is the ICD-10 code for bilateral knee pain?
There’s no single bilateral code. Report M25.561 (right) and M25.562 (left) together. M25.569 means the side is unspecified, not both knees.
What is the ICD-10 code for chronic right knee pain?
Use M25.561 with G89.29 (other chronic pain). Sequence G89.29 first only when the visit is mainly for pain management.
What is the ICD-10 code for right knee osteoarthritis?
M17.11, unilateral primary osteoarthritis of the right knee. It also covers degenerative joint disease (DJD) of the right knee. Bilateral knee OA is M17.0.
What is the ICD-10 code for a right knee sprain?
S83.91XA for a sprain of an unspecified site of the right knee at the initial encounter. Use a ligament-specific code, such as S83.511A for the ACL, when the ligament is documented.
What is the ICD-10 code for right knee swelling?
M25.461, effusion of the right knee. ICD-10-CM indexes joint swelling to effusion. Add M25.561 if the provider also documents pain and no diagnosis is confirmed.
