ModifiedPremera BluecrossPolicy 7.01.48

Cartilage Lesions (Autologous Chondrocyte Implantation — ACI/MACI)

Defines medical necessity and coverage criteria for autologous chondrocyte implantation (ACI/MACI) for focal, full-thickness cartilage lesions of the knee and states that ACI for other joints is investigational; includes site-of-service considerations for elective surgical procedures.

Policy Summary

PayerPremera Bluecross

PolicyCartilage Lesions (Autologous Chondrocyte Implantation — ACI/MACI)

Policy CodePolicy 7.01.48

Change TypeRelated-policy updates, coding removal (29870), documentation corrections

Effective DateNov 7, 2025

Next Review Date

Key ActionObtain prior authorization and submit clinical documentation demonstrating criteria are met (defect size, Outerbridge grade, stability, and product-aligned indications) before scheduling knee ACI.

SourceLink

POLICY UPDATE CHANGES

Removed Related Policy 11.01.524 Site of Service: Select Surgical Procedures.

Added related policy 11.01.525 Site of Service Ambulatory Service Center (ASC) Select Surgical Procedures and ASC criteria.

Replaced related policy 7.01.78 Osteochondral Autografts in the Treatment of Articular Cartilage Lesions with 7.01.607 Autografts and Allografts in the Treatment of Focal Articular Cartilage Lesions.

Correction made to Documentation Requirements section to remove BMI and need for MRI results which were inadvertently left on previously.

Removed CPT code 29870.

15-55Age range

≥1.5 cm2Min lesion size

III–IV

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Knee onlyCoverage stance

InsufficientNon-knee evidence

11/07/2025Policy change date

Coverage Criteria for Autologous Chondrocyte Implantation (ACI/MACI)

Medical necessity criteria for knee ACI

Autologous chondrocyte implantation (ACI/MACI) of the knee is covered when ALL of the following are met:

ACI knee coverage criteria: Severe disabling knee pain and loss of knee function from acute or repetitive trauma interfering with activities of daily living or work; individual is skeletally mature (adolescents ≈≥15 years) or an adult who is a candidate where arthroplasty is undesirable (e.g., typically <55 years); focal, full-thickness (Outerbridge grade III or IV) unipolar lesions of the weight-bearing surface of the femoral condyles, trochlea, or patella that are at least 1.5 cm^2 in size; documented minimal to absent degenerative changes in surrounding articular cartilage (Outerbridge grade II or less) with normal-appearing hyaline cartilage at the defect border; knee is stable (intact or reconstructed ligaments) or ligament repair is planned with the procedure; normal joint alignment; normal joint space.

Knee ACI — covered with criteria

Covered when ALL of the following are met (documented in the medical record and consistent with product labeling and guideline statements):

Knee ACI coverage (product- and guideline-aligned)

Defect size and osteoarthritis assessment: Defect size meets product or guideline thresholds (e.g., NICE: defect >2 cm^2); product labeling may specify treatable ranges (example: Agili-C 1–7 cm^2). Clinician assessment documents minimal osteoarthritic damage to the knee.
Treatment history and prior procedures: Consideration of prior surgical procedures: for smaller lesions (<4 cm^2) prior marrow-stimulating techniques (e.g., microfracture) or prior repair may be considered; evidence supports ACI over microfracture for large lesions and long-term outcomes. Document prior procedures and rationale if prior surgery was not performed.

Investigational indications

Not covered / investigational:

Investigational indications: Autologous chondrocyte implantation (ACI) for all other joints (including talus/ankle, hip, and other non-knee joints) and for indications other than those listed for the knee is considered investigational due to insufficient evidence to determine net health benefit.

Non-knee joints — insufficient evidence

Not established / insufficient evidence for coverage:

Non-knee joints: ACI for focal articular cartilage lesions in joints other than the knee (e.g., talus/ankle, hip) lacks sufficient comparative evidence (primarily case series and systematic reviews of case series); comparative trials are needed to determine net health benefit.

Coverage criteria (summary)

Policy statements governing when ACI/MACI is considered medically necessary remain as previously established; this window documents updates to related policies, documentation corrections, and coding changes.

Policy stability and updates summary: Coverage criteria for ACI/MACI of the knee are unchanged through recent reviews. Related administrative updates include site-of-service policy changes, documentation clarifications (removal of BMI and mandatory MRI fields), and coding updates (removal of CPT 29870). Prior authorization and documentation requirements should follow the current policy and product labeling.

In addition to the specific lesion and age criteria for knee ACI, the policy identifies several factors that contraindicate or otherwise affect candidacy. Joint misalignment and instability are contraindications unless corrected; corrective procedures (for example, osteotomy or ligament repair) may be performed concurrently or staged with ACI. Severe obesity (BMI >35 kg/m2) may negatively affect outcomes because of increased stress on weight-bearing surfaces. Documentation should reflect any concurrent procedures and the rationale for proceeding when these factors are present.

The policy also notes procedural steps and practical considerations related to ACI: the procedure generally involves initial diagnostic arthroscopy and cartilage biopsy, ex vivo chondrocyte culturing on a matrix, a separate arthrotomy for implantation, and postoperative rehabilitation. Charge and billing for the culturing component are submitted as part of the hospital bill.

The policy limits standard coverage to knee joints and cites guideline and evidence context for excluding other joints. The National Institute for Health and Care Excellence (NICE) recommends ACI as an option for symptomatic focal femoral condyle and patellar defects only when specific conditions are met (including defect size >2 cm2 and minimal osteoarthritic change), reflecting a more established evidence base for the knee than for other joints.

For joints other than the knee (for example, talus/ankle, hip), the available literature is mainly case series and systematic reviews of case series; comparative trials are lacking. Because of this limited and lower-quality evidence, the policy excludes routine coverage of non-knee joints and treats those indications as investigational.

This medical policy is a guideline to evaluate medical necessity and does not apply to Medicare Advantage plans. Member benefits vary by contract, and coverage determinations for Medicare Advantage enrollees should be made using the applicable Medicare Advantage plan documents and procedures.

Autologous chondrocyte implantation (ACI) for indications or joints other than the specified knee indications is considered investigational and not medically necessary. This includes ACI performed for focal cartilage lesions in the talus/ankle and other non-knee joints because the policy’s coverage criteria are limited to symptomatic, focal, full-thickness knee lesions that meet the stated size, Outerbridge grade, alignment, stability, and degeneration thresholds.

When ACI is requested for non-knee joints, prior authorization should reflect the investigational status and supporting medical record documentation; absent sufficient comparative evidence showing a net health benefit for these joints, requests may be denied.

The investigational/experimental designation for ACI in non-knee joints is based on insufficient evidence of benefit. The literature for non-knee applications is dominated by case series and retrospective reports, with a lack of well-controlled comparative trials. As a result, the policy concludes that current evidence is inadequate to determine whether ACI improves symptoms, functional outcomes, or quality of life for lesions in joints other than the knee.

Historically, the policy has stated that autologous chondrocyte implantation is considered investigational when the stated coverage criteria are not met. This position has been included in prior policy iterations and remains the policy stance when an individual’s presentation falls outside the defined clinical criteria for medically necessary knee ACI.

Coding and Quantitative Criteria

Covered CPT Codes (procedure-related)CPTCovered

27412	Autologous chondrocyte implantation, knee
29877	Arthroscopy, knee, surgical; debridement/shaving of articular cartilage (chondroplasty)
29879	Arthroscopy, knee, surgical; abrasion arthroplasty (includes chondroplasty where necessary) or multiple drilling or microfracture
29880	Arthroscopy, knee, surgical; with meniscectomy (medial AND lateral, including any meniscal shaving) including debridement/shaving of articular cartilage (chondroplasty)
29881	Arthroscopy, knee, surgical; with meniscectomy (medial OR lateral, including any meniscal shaving) including debridement/shaving of articular cartilage (chondroplasty)
29882	Arthroscopy, knee, surgical; with meniscus repair (medial OR lateral)
29883	Arthroscopy, knee, surgical; with meniscus repair (medial AND lateral)

HCPCS / supply codesHCPCSCovered

J7330	Autologous cultured chondrocytes, implant
S2112	Arthroscopy, knee, surgical, for harvesting of cartilage (chondrocyte cells)

Clinical trial identifiers from Table 2mixed

NCT04785092	Clinical trial identifier listed in ongoing trials table
NCT03219307	Clinical trial identifier listed in ongoing trials table
NCT04744402	Clinical trial identifier listed in ongoing trials table
NCT01957722	Clinical trial identifier listed in ongoing trials table
NCT05651997	Clinical trial identifier listed in ongoing trials table
NCT05402072	Clinical trial identifier listed in ongoing trials table
NCT01656902	Clinical trial identifier listed in ongoing trials table

Removed CPT Codes / Coding updatesCPTNot Covered

29870

Arthroscopy, knee, resection/shaving of articular cartilage (removed from policy)

Minimum lesion size for coverage

Minimum lesion sizeAt least 1.5 cm^2 for focal, full-thickness (Outerbridge grade III or IV) unipolar lesions of weight-bearing femoral condyles, trochlea, or patella

Lesion location requirementWeight-bearing surface of femoral condyles, trochlea, or patella

Full-thickness requirementLesion must be full-thickness (Outerbridge grade III or IV)

Age thresholds

Skeletal maturity (adolescents)Skeletally mature — approximately ≥15 years of age

Adult candidate consideration

Provider Requirements, Prior Authorization, and Denial Risks

Prior Authorization

Prior Authorization: product-aligned indications

Prior authorization is required for ACI procedures and requests should align to product-specific indications. When submitting for knee ACI, reference FDA-approved product labeling (e.g., MACI) and include product name if a commercially approved ACI product will be used.

Prior authorization required before scheduling ACI implantation.
When applicable, identify the ACI product (e.g., MACI, Agili-C) on the authorization request and attach FDA labeling or product-specific information.

Denial Risk

Site-of-service denial risk

Perform elective ACI procedures in the most appropriate, safe, and cost-effective site of service. Performing an elective procedure in an inpatient setting when outpatient/ASC is appropriate may result in denial or site-of-service cost-share adjustments.

Preferred medically necessary site: Ambulatory Surgical Center (ASC) when capable and available.

Background and Clinical Context

Articular cartilage defects typically cause pain and functional loss and have limited capacity for spontaneous healing. Autologous chondrocyte implantation (ACI/MACI) harvests a patient’s chondrocytes, expands them in vitro, and implants them to promote regeneration of hyaline-like cartilage. Matrix-associated techniques (MACI) use a bioresorbable collagen scaffold to deliver cultured chondrocytes and are a second-generation approach designed to simplify implantation compared with first-generation ACI.

Clinically, ACI is intended for focal, full-thickness (Modified Outerbridge grade III–IV) defects of the weight-bearing surfaces of the femoral condyles, trochlea, or patella when surrounding cartilage shows minimal degenerative change. Treatment typically involves an initial arthroscopy with biopsy, ex vivo cell culturing, a separate implantation procedure, and structured postoperative rehabilitation; candidate selection and lesion characteristics (for example, minimum lesion size and joint stability) are important predictors of appropriate use and expected outcomes.

Definitions and Classifications

Modified Outerbridge Grades III–IV

Grade III definitionPartial‑thickness cartilage loss with focal ulceration (Modified Outerbridge Grade III)

Grade IV definitionFull‑thickness cartilage loss with underlying bone reactive changes and exposed subchondral bone (Modified Outerbridge Grade IV)

Use in policyPolicy requires focal, full‑thickness lesions (Grade III or IV) for coverage of ACI

ASA / NYHA scores referenced for anesthetic/cardiac risk

ASA classificationAmerican Society of Anesthesiologists (ASA) score used to define anesthetic risk (ASA 1–5 scale)

NYHA classificationNew York Heart Association (NYHA) class I–IV used to define cardiac functional status for site‑of‑service decisions

Policy Revision History and Updates

2026-04-01coding_update

CPT code 29870 was removed from the policy CPT list (coding update).

2025-11-07related_policy/site_of_service_change

Related policy 11.01.524 (Site of Service: Select Surgical Procedures) was removed and related policy 11.01.525 (Site of Service Ambulatory Service Center (ASC) Select Surgical Procedures) was added; ASC criteria applied, with these changes effective November 7, 2025 following provider notification.

2025-08-01interim_review

Policy Summary

PayerPremera Bluecross

PolicyCartilage Lesions (Autologous Chondrocyte Implantation — ACI/MACI)

Policy CodePolicy 7.01.48

Change TypeRelated-policy updates, coding removal (29870), documentation corrections

Effective DateNov 7, 2025

Next Review Date

SourceLink

On This Page

Adults typically considered for candidate selection when younger than ~55 years

Policy age range summaryPolicy references an age range of 15 to 55 years for candidate selection

Defect size treatable per guidance or device labeling

Agili‑C treatable area (labeling)Agili‑C FDA‑approved treatable area: 1 to 7 cm^2 for knee‑joint surface lesions

NICE defect size thresholdNICE recommends ACI only if the defect is over 2 cm^2

Guideline vs device noteProduct labeling may specify ranges (e.g., 1–7 cm^2) while NICE uses a >2 cm^2 threshold for consideration

Minimum age for ACI in prior history notes

Historical minimum age referencePrior policy/history notes reference a minimum age of 15 years for skeletal maturity when considering ACI

RationaleAge 15 approximates skeletal maturity considered in policy; cited in policy history and age consideration section

Documentation implicationMedical record should document individual's age and skeletal maturity status when applicable

If an ASC cannot provide necessary care (no geographically accessible ASC within 30 miles, lack of equipment, or lack of surgeon privileges), document the reason for an outpatient hospital site selection.

Denial Risk

Investigational indication denial risk

ACI for joints other than the knee (for example, talus/ankle and other non-knee joints) is considered investigational due to insufficient evidence and may be denied.

ACI indications limited to knee (femoral condyles, trochlea, patella) per policy; requests for non‑knee joints are investigational.
Clinical justification and supporting evidence do not typically meet medical necessity for non‑knee joints and are subject to denial.

Step Therapy

Consider prior marrow-stimulating techniques for smaller lesions

For focal, smaller lesions (< 4 cm2) where prior surgical treatment has been limited to debridement, consider marrow‑stimulating techniques (e.g., microfracture) before proceeding to ACI.

Document prior debridement as the only prior surgical treatment when considering a marrow-stimulating technique.
Provide rationale if skipping marrow-stimulating techniques and proceeding directly to ACI.

Step Therapy

Step therapy considerations

Step therapy and prior-line surgical history should be considered when evaluating ACI requests; evidence context supports considering prior less-invasive surgical options (microfracture, marrow stimulation) especially for smaller lesions and as part of treatment sequencing.

Document prior surgical history and responses to prior procedures.
Describe why ACI is medically necessary now versus prior treatments.

Documentation Required

Required clinical documentation

Required clinical documentation must be submitted with authorization requests to demonstrate that medical necessity criteria are met.

Office visit notes with relevant history and physical exam, including individual's age.
Lesion description and size (cm2) and Outerbridge grade for the defect and surrounding cartilage.
Documentation of prior treatments (conservative care and any prior surgical procedures) and current joint stability, alignment, and joint space.

Documentation Required

Regulatory / product documentation

When applicable, include regulatory and product documentation with the prior authorization submission. Reference FDA approvals for marketed products (e.g., MACI, AgiliC) to demonstrate product-specific indications for knee ACI.

Attach or reference FDA product labeling or approval documentation when a specific commercial ACI product is planned.
If using an investigational or non‑US product, note lack of FDA approval and provide supporting evidence; such use may be considered investigational.

Documentation Required

Documentation correction

Documentation corrections: follow current documentation requirements. Administrative corrections previously removed BMI and mandatory MRI fields from documentation requirements; do not include BMI or mandatory MRI results unless currently required by policy or product labeling.

Use the current Documentation Requirements section — do not reintroduce BMI ≤35 or mandatory MRI fields that were removed.
If product labeling requires additional data, include that specific information; otherwise follow standard documentation list.

Site‑of‑service relevanceASA and NYHA scores are referenced when assessing anesthetic/cardiac risk for ambulatory vs inpatient site selection

Second‑generation ACI / MACI definition and characteristics

DefinitionSecond‑generation ACI/MACI: autologous chondrocytes cultured and seeded onto a bioresorbable collagen or polymer scaffold/membrane for implantation

Technical characteristicLess technically demanding implantation than first‑generation ACI; uses a matrix scaffold to deliver cells

Clinical contextMACI approved by FDA (2016) and replaced Carticel production; evidence shows mid‑term outcomes approximating first‑generation ACI

Agili‑C device definition and treatable area per labeling

Agili‑C descriptionAgili‑C is a proprietary biocompatible, biodegradable tapered‑shape implant acting as a 3‑D scaffold when implanted into a prepared osteochondral hole

FDA approval and indicationFDA‑approved in 2021 for treatment of knee‑joint surface lesions with a treatable area of 1 to 7 cm^2 without severe osteoarthritis

Intended effectSupports and promotes regeneration of articular cartilage and underlying subchondral bone

ACI / MACI abbreviation definitions

ACIAutologous chondrocyte implantation — implantation of a patient’s cultured chondrocytes to repair focal cartilage defects

MACI (mACI)Matrix‑associated autologous chondrocyte implantation — chondrocytes seeded on a bioresorbable scaffold/membrane for implantation

Usage noteMACI is a second‑generation ACI technique; terms ACI and MACI are used in the policy to describe autologous chondrocyte–based repair procedures

Interim review approved July 8, 2025 documenting removal of related policy 11.01.524 and planned effective date of November 7, 2025 for ASC-related updates and related-policy renumbering.

2025-07-01annual_review

Annual literature review through February 17, 2025 was completed and policy statements remained unchanged (annual review approved June 9, 2025).

2024-07-01annual_review

Annual literature review through February 20, 2024 was completed and policy statements remained unchanged (annual review approved June 10, 2024).

2023-09-08documentation_correction

Correction made to Documentation Requirements to remove BMI and mandatory MRI result fields that were inadvertently left on previously.

2023-07-01annual_review_and_standardization

Annual review approved June 12, 2023 with literature update through February 16, 2023 and wording standardized from 'patient' to 'individual'; policy statements unchanged.

2020-04-01coding_and_site_of_service_change

Multiple CPT codes and HCPCS S2112 were removed from the policy on April 1, 2020 as part of site-of-service criteria adjustments (policy notes removal of CPTs including 29870 in that update).