The International Classification of Diseases, 10th Revision (ICD-10) provides a universal system for documenting diagnoses, enabling standardized communication among healthcare providers, insurers, and regulatory agencies.
Among the many frequently coded conditions, left knee pain is one of the most common musculoskeletal issues seen in outpatient settings. Whether it's due to injury, overuse, or degenerative conditions, correctly identifying the ICD-10 code for left knee pain is crucial for accurate documentation, effective treatment, and proper reimbursement.
What Is the ICD-10 Code for Left Knee Pain?
M25.562 – Pain in left knee
This ICD-10-CM diagnosis code applies when the pain is localized to the left knee and no more specific diagnosis (like a tear or osteoarthritis) has been established. It's a symptom-based code, often documented in the medical record during the initial evaluation or when pain exists without a known underlying condition.
Why Is the ICD-10 Code Important?
Correct ICD-10 coding ensures:
Accurate diagnosis code recording in the patient chart
Smooth insurance claims processing
Improved clinical communication for effective patient management
Proper billing and reimbursement
Using M25.562 not only communicates the patient's condition but also protects your practice from potential denials and compliance issues. When applicable, coders may also convert to ICD-9-CM for historical data mapping and legacy record purposes.
Left Knee Pain Terminologies and Their ICD-10 Descriptions
Let’s break down how different scenarios of pain in joint conditions like left knee pain are coded in ICD-10. Each variation helps capture the full clinical picture and ensure accurate documentation of joint disorders.
| Condition / Scenario | ICD-10 Code | Code Description |
|---|---|---|
| General Left Knee Pain | M25.562 | Pain in the left knee |
| Left Knee Joint Pain (no confirmed diagnosis) | M25.562 | Same as above – symptom-based code used when no underlying cause is known |
| Osteoarthritis of the Left Knee | M17.12 | Unilateral primary osteoarthritis, left knee |
| Left Knee Pain with Swelling | M25.562 + M25.362 | Pain + Swelling of left knee (use both if both are clinically significant) |
| Left Knee Pain After a Fall | M25.562 + W19.XXXA | Pain + External cause (unspecified fall) — use correct extension for situation |
| Injury to Left Knee (unspecified) | S80.912A | Unspecified superficial injury of left knee, initial encounter |
| Left Knee Sprain (ligament-related) | S83.92XA | Sprain of unspecified site of left knee, initial encounter |
| Left Knee Strain (muscle/tendon-related) | S86.812A | Strain of other muscle(s) and tendon(s) at the lower leg level, left leg, initial |
| Left Knee Pain with Effusion | M25.562 + M25.462 | Pain + Effusion (fluid buildup) in the left knee |
| Unspecified Left Knee Pain | M25.562 | The default code when no further details are available |
1. ICD-10 Pain in Left Knee – M25.562
This is the default and most frequently used code for general, nonspecific pain in the left knee. Use it when the source of pain hasn’t been diagnosed but is documented in the medical record as present. For patients with chronic pain due to degenerative or overuse conditions, a more specific diagnosis code should be selected.
2. Left Knee Joint Pain ICD-10 – M25.562
3. Left Knee Osteoarthritis ICD-10 – M17.12
M17.12 – Unilateral primary osteoarthritis, left knee
This provides greater specificity for both clinical and billing purposes.
Want to learn more about arthritis-related codes? See our ICD-10 Codes for Osteoarthritis guide.
4. L Knee Pain ICD-10 – M25.562
5. Left Knee Injury ICD-10 – S80.912A
S80.912A – Unspecified superficial injury of left knee, initial encounter
Remember: For injury codes (S-codes), the 7th character ‘A’ is for the initial encounter. Use ‘D’ for subsequent and ‘S’ for sequela.
Always pair with an external cause code if the injury was from trauma (e.g., fall, accident).
6. Left Knee Sprain ICD-10 – S83.92XA
S83.92XA – Sprain of unspecified site of left knee, initial encounter
This is appropriate when ligament damage is suspected or confirmed but not specified.
7. Left Knee Strain ICD-10 – S86.812A
Muscle or tendon strains in the left knee area should be reported as:
S86.812A – Strain of other muscle(s) and tendon(s) at lower leg level, left leg, initial encounter
Be sure documentation includes details on whether it’s a muscle or tendon strain.
Specific Scenarios & How to Code Them
1. Left Knee Pain and Swelling
- M25.562 for the pain
- M25.362 for swelling of the left knee
2. Left Knee Pain After a Fall
If pain follows a fall, you’ll typically need:
- M25.562 for the pain
- W19.XXXA for “unspecified fall, initial encounter”
Use W19.XXXA – Unspecified fall, initial encounter (replace ‘XXX’ with appropriate extension if needed based on cause or location of fall).
This coding supports both the symptom and the mechanism of injury, improving billing accuracy.
3. Left Knee Pain Unspecified
4. Left Knee Pain with Effusion
Effusion (fluid buildup) in the joint indicates a more specific issue. In this case:
- M25.562 for pain
- M25.462 – Effusion, left knee
This dual coding approach ensures the full scope of the condition is documented.
5. Left Knee Pain Due to Osteoarthritis
When osteoarthritis is confirmed, always code the condition, not just the symptom:
Use M17.12 rather than M25.562
This provides diagnostic clarity and prevents downcoding.
2025 ICD-10 Coding Tips for Knee Pain
As of the 2025 ICD-10 updates, no major changes were made to these codes, but here are some best practices to follow:
- Always confirm laterality (left, right, or bilateral)
- Use initial encounter (A), subsequent (D), or sequela (S) as needed for injuries
- Match symptoms to causes when possible to avoid overusing symptom codes like M25.562
- If imaging or specialist evaluation confirms a cause (e.g., meniscus tear, arthritis), code that condition directly
Why Accurate Coding Matters
Proper ICD-10 coding improves not only clinical documentation but also ensures:
Faster insurance approval
Fewer claim rejections or audits
Improved care coordination across providers for effective patient management
Data tracking for outcomes and population health
Incorrect use of symptom codes (like M25.562) without identifying the root cause of joint disorders can lead to denials or downcoding, especially in follow-up visits or chronic conditions.
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