Autologous Chondrocyte Implantation (ACI)
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Defines medical necessity criteria and exclusions for autologous chondrocyte implantation (ACI)/matrix-induced ACI (MACI) for focal full-thickness chondral defects of the knee, and specifies provider requirements for patient selection.
No material clinical or coverage changes in this revision.
Coverage Criteria for Autologous Chondrocyte Implantation (ACI/MACI)
Initial therapy / eligibility
Covered when ALL of the following are met
Primary eligibility
- Demographics/health: Body mass index (BMI) ≤ 35 (chunk 2) AND age 15–55 years (chunk 3) AND absence of inflammatory arthritis or other systemic disease affecting the joints (chunk 4)
- Radiographic/arthroscopic findings: Kellgren-Lawrence Grade II or less on radiographs (chunk 5) AND normal articular cartilage at the lesion border (contained lesion) (chunk 6)
- Lesion characterization: Contained, full-thickness chondral defect of the distal femur (medial condyle, lateral condyle, or trochlea) or patella sized 1–10 cm^2 identified by CT arthrogram (chunk 7), or MRI with Modified Outerbridge Grade III or IV (chunk 8), or arthroscopy with Outerbridge Grade III or IV (chunk 9)
- Exclusions related to lesion type: Absence of an osteochondritis dissecans (OCD) lesion that requires bone grafting (chunk 10) AND absence of a corresponding 'kissing lesion' Modified Outerbridge Grade III or IV on opposing surfaces when performed for femoral/patellar lesions (chunk 11)
- Knee stability and alignment: Stable knee with intact or reconstructed ligaments and menisci (concurrent ligament stabilization or meniscal procedure acceptable) (chunk 12) AND normal tibiofemoral or patellofemoral alignment (chunk 14)
- Symptoms and prior care: Function-limiting knee pain or loss of knee function interfering with age-appropriate activities of daily living (chunk 15) AND failure of provider-directed non-surgical management for at least 3 months (chunk 16)
See documentation requirements in policy
Coverage Position and Limitations
Policy stance and limits
Supported by peer-reviewed studies including STAR and SUMMIT (chunks 34,35,39,40)
Enumerated contraindications/conditions
Policy classifies these techniques as investigational
Policy aligns coverage with product labeling when applicable
Coverage for MACI (knee)
Covered when ALL of the following are met
Supported by SUMMIT Phase 3 trial and extension data (chunks 39,40) and FDA approval (chunk 47)
Skeletally immature patients
Considered investigational/limited evidence when in skeletally immature patients
Routine coverage not established; use caution and require detailed documentation when considered
ACI for joints other than the knee
Not routinely covered / insufficient evidence when for non-knee joints unless exceptional documentation
Small positive series exist but are low-level evidence; further studies required (chunks 41–43)
Autologous chondrocyte implantation (ACI) is not medically necessary for indications or conditions outside the policy’s specified coverage criteria. Examples of exclusionary conditions include: any knee joint surgery within six (6) months before screening (except procedures to obtain a biopsy or concomitant preparation for a MACI implant), prior total meniscectomy, meniscal allograft, or bucket-handle/displaced tear requiring >50% meniscal removal in the target knee, and septic arthritis within one (1) year before screening.
Hybrid techniques combining ACI with osteochondral autograft transfer systems (Hybrid ACI/OATS) are classified as investigational and are excluded from coverage. Similarly, minced cartilage repair techniques (for example, the DePuy Mitek cartilage autograft implantation system and the DeNOVO NT Graft) lack well-designed published studies demonstrating safety and effectiveness compared with standard techniques and are considered investigational and not covered.
The MACI package insert lists specific contraindications that preclude appropriate use. These include known hypersensitivity to gentamicin or other aminoglycosides or to porcine/bovine products, severe osteoarthritis or inflammatory joint disease, uncorrected congenital blood coagulation disorders, prior knee surgery within 6 months (except biopsy or concomitant preparation procedures), and inability to comply with prescribed post-surgical rehabilitation. Presence of these contraindications would be exclusionary for ACI/MACI.
Autologous chondrocyte implantation is not addressed in national or regional Medicare coverage determinations or policies; there is no CMS national or regional coverage guidance for ACI documented in this policy.
ACI is explicitly not medically necessary when performed outside the policy’s defined eligibility criteria or when one or more of the listed exclusionary conditions are present. Examples that would render ACI not medically necessary include recent knee surgery within six (6) months (other than biopsy or concomitant preparation), extensive meniscal loss or prior procedures requiring >50% meniscal removal, and prior septic arthritis within one (1) year before screening.
ACI is considered not medically necessary for several patient conditions and contraindications, including: total meniscectomy or large meniscal resection (>50%) in the target knee, septic arthritis within 1 year before screening, known hypersensitivity to gentamicin/other aminoglycosides or to porcine/bovine products, uncorrected congenital coagulation disorders, and cruciate ligament instability.
Use of ACI for focal cartilage lesions in joints other than the knee (for example, talus or hip) is supported only by limited, low-level evidence (small case series and observational reports). The evidence is insufficient to determine effects on health outcomes, and routine coverage for non-knee joints is not established; such indications are considered investigational or not medically necessary unless exceptional documentation supports benefit.
Coding and Clinical Thresholds
| 27412 | Autologous chondrocyte implantation, knee |
| M12.561-M12.569 | Traumatic arthropathy, knee (code range) |
| M17.0-M17.9 | Osteoarthritis of knee (code range) |
| M23.50-M23.52 | Chronic instability of knee (code range) |
| M23.92 | |
| M25.261-M25.269 | |
| M25.361-M25.369 | |
| M25.861 | Other specified joint disorder, knee (code range) |
| M85.9 | Disorder of bone density and structure, unspecified |
| M89.8X6 | Other specified disorders of bone, lower leg |
| M89.9 | Disorder of bone, unspecified |
Provider Actions, Authorization, and Documentation Requirements
Prior authorization required to confirm eligibility criteria
Submit prior authorization to confirm the member meets all medical necessity criteria prior to ACI: age 15–55, BMI ≤35, documented contained full‑thickness chondral defect (1–10 cm2) by CT arthrogram, MRI (Modified Outerbridge Grade III/IV) or arthroscopy (Outerbridge Grade III/IV), stable knee ligaments/menisci and normal tibiofemoral or patellofemoral alignment, and failure of ≥3 months of provider‑directed non‑surgical management.
- Provide imaging or arthroscopy reports documenting lesion size (1–10 cm2) and grade.
- Document prior non‑surgical management of at least 3 months and clinical symptoms interfering with age‑appropriate ADLs.
Prior authorization expected for staged ACI/MACI procedures
Prior authorization is expected because MACI/ACI is a staged, multi‑step procedure (initial diagnostic arthroscopy/biopsy, cell culture, then separate implantation arthrotomy) and clinical history must show failed prior treatments and lesion characterization.
- Include diagnostic arthroscopy/biopsy and planned cultured chondrocyte implantation details in the authorization request.
- Attach chronology of prior failed cartilage repair or conservative treatments.
Prior authorization required when billing listed procedure and diagnosis codes
Obtain prior authorization when billing ACI/MACI CPT/HCPCS or relevant ICD‑10 codes; verify clinical criteria and contraindications are met before approval.
Coverage and prior authorization are product‑dependent
Confirm whether the member's product covers ACI/MACI before applying policy criteria; product benefits and contract rules determine prior authorization and coverage applicability.
- If the product does not cover the service, medical policy criteria do not apply.
- If the product does cover the service (commercial, Medicaid without eMedNY guidance, or Medicare without NCD/LCD), apply the medical policy criteria and require authorization as appropriate.
Conservative therapy prerequisite: ≥3 months documented
Document at least three months of provider‑directed, non‑surgical management (conservative therapy) before ACI is considered.
- Conservative management documentation should include dates, therapies tried, duration, and response (e.g., physical therapy, injections, bracing).
Require documented failure of prior therapies
Demonstrate failure of prior conservative management and, where applicable, prior arthroscopic or other surgical treatments before ACI will be considered medically appropriate.
- Provide records showing prior surgical cartilage repair attempts and outcomes when relevant to the case.
Sequencing considerations per NICE (no prior cartilage repair; defect >2 cm2)
Consider sequencing per NICE guidance: ACI should be used only if there has been no previous surgery to repair articular cartilage defects and when the defect is >2 cm2 and osteoarthritic damage is minimal.
- If prior cartilage repair surgery was performed, document timing and type; NICE suggests no prior surgical repair for cartilage defects when considering ACI.
- Document that care is at an appropriate center when aligning with guideline recommendations.
Required clinical documentation: imaging/arthroscopy demonstrating contained full‑thickness defect
Providers must submit imaging or arthroscopic findings demonstrating a contained, full‑thickness chondral defect (1–10 cm2) on the distal femur or patella with Modified Outerbridge or Outerbridge Grade III/IV as part of the authorization and medical record.
- Include specific lesion location and measured size (cm2), grading (Modified Outerbridge or Outerbridge), and confirmation of a contained lesion (normal cartilage at lesion border).
- Provide documentation of symptoms (function‑limiting pain or loss of function) and prior conservative management duration.
Document prior arthroscopic/surgical repairs, biopsy/culture, and failed conservative care
Include clinical and procedural documentation of prior arthroscopic or other surgical repair procedures, diagnostic arthroscopy and cartilage biopsy (if performed), the culturing process, and evidence of failure of conservative management to support ACI requests.
- Attach operative reports, biopsy/culture records, and notes describing prior repair procedures and their outcomes.
- Provide timeline showing biopsy, culturing, and planned implantation dates when applicable.
Required clinical documentation elements to support ACI
Ensure documentation supports prior failed cartilage repair when applicable, describes the extent of osteoarthritic damage, and records lesion size (note: NICE references defects >2 cm2); include evidence that care is provided at an appropriate center when following guideline recommendations.
- Explicitly state prior cartilage repair failures in records and quantify osteoarthritic damage (validated measure or Kellgren‑Lawrence grade).
- Record lesion size and reference NICE criteria (>2 cm2) if used to justify treatment sequencing.
Document product coverage when applying policy criteria
When coverage depends on a commercial, Medicaid (without eMedNY guidance), or Medicare product (without a national/local coverage decision), document that the product covers ACI so medical policy criteria may be applied.
- Include product/plan information in the authorization request to confirm benefit applicability.
- If the product does not cover the service, deny/decline per contract; medical policy criteria are not applicable.
Denial risk: recent knee surgery, extensive meniscal loss, or recent septic arthritis
Claims may be denied if ACI is performed within six months of any knee joint surgery (except biopsy or concomitant preparation procedures), after total meniscectomy or meniscal loss >50% in the target knee, or following septic arthritis within one year before screening.
- Do not schedule implantation within six months of prior knee surgery other than biopsy or preparation procedures; document timing of any prior knee surgery.
- Document meniscal status and exclude cases with >50% meniscal removal from coverage consideration.
Denial risk: contraindications present or investigational hybrid/minced techniques
Requests will be denied as not medically necessary for the listed contraindications and for investigational hybrid techniques (Hybrid ACI/OATS and minced cartilage repair); verify none of these exclusions apply.
- Excluded conditions include total meniscectomy or meniscal loss >50%, septic arthritis within 1 year, known hypersensitivity to gentamicin/aminoglycosides or porcine/bovine products, uncorrected congenital coagulation disorders, and cruciate ligament instability.
- Hybrid ACI/OATS and minced cartilage repair techniques are investigational and not covered.
Contraindications per MACI labeling may trigger denial
Check MACI package‑insert contraindications before proceeding; severe osteoarthritis, inflammatory arthritis, prior knee surgery within 6 months (except biopsy/prep), hypersensitivity to porcine/bovine products or aminoglycosides, and uncorrected coagulation disorders are contraindications that may preclude coverage.
- Document absence of MACI contraindications in the medical record and authorization submission.
- If any MACI contraindication is present, the request is subject to denial.
Contract/benefit coverage dependency — verify plan covers ACI
Verify contract/plan coverage for the service before authorization; if the member's product does not cover ACI, the medical policy criteria do not apply and the claim may be denied for lack of benefit coverage.
- Include plan/product identifier and confirm benefit coverage in the authorization request.
- Follow product‑specific rules (Essential Plan, Child Health Plus, Medicaid, Medicare) as described in the product disclaimer.
Background and Evidence Summary
Autologous chondrocyte implantation (ACI), including matrix-associated ACI (MACI), is a cell-based cartilage repair technique intended for contained, full-thickness chondral defects of the distal femur or patella in selected patients. MACI is an FDA-approved, cellularized scaffold product (approved December 2016) for repair of symptomatic full-thickness knee cartilage defects in adults. Patient selection considers lesion size, cartilage status at the lesion border, joint alignment, ligament/meniscal stability, absence of inflammatory or systemic arthritis, and prior failure of conservative management.
Definitions and Classifications
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