CARTIHEAL Agili-C — Aragonite Biphasic Scaffold

Why this approach — at MOS

Agili-C is the first cartilage restoration implant we can offer patients who already have arthritis. Every other cartilage procedure (microfracture, OATS, osteochondral allograft, MACI) requires a knee that is otherwise near-normal, and Kellgren-Lawrence Grade 2 or 3 arthritis has historically disqualified a patient from cartilage repair altogether. Agili-C is FDA-approved for Kellgren-Lawrence Grade 0–3, which is why a group of patients who previously had nothing between injections and knee replacement now has a reconstructive option.

It is also a single-stage, off-the-shelf implant: no cartilage biopsy, no six-week cell culture, no second operation. When we identify malalignment, meniscal deficiency, or ligamentous instability at the time of surgery, we correct it in the same setting. The mechanical environment of the knee is what protects the implant over the long term, and we do not treat the cartilage in isolation.

The pivotal multicenter randomized trial: 2-year results

The pivotal trial (Altschuler et al., *American Journal of Sports Medicine*, 2023) randomized 251 patients at 20 sites in 8 countries to Agili-C or standard of care (microfracture and debridement), with 24-month follow-up:

• Responder rate (≥30-point KOOS improvement): 77.8% with Agili-C vs. 33.6% with standard of care
• Structural repair (MRI defect fill ≥75%): 88.5% vs. 30.9% at 24 months
• Failure rate: 7.2% vs. 21.4%
• Osteoarthritis subgroup: patients with Kellgren-Lawrence Grade 1–3 arthritis did as well as patients without arthritis
• Multiple lesions: patients treated for up to three defects in one operation did as well as single-lesion patients

Five-year follow-up

Five-year data (Altschuler et al., AJSM, 2026) show the advantage over standard of care was maintained across every KOOS subscale through 60 months, with sustained structural repair on MRI. The conversion rate to knee replacement or osteotomy was 1.8% in the Agili-C group vs. 9.5% in the standard-of-care group, an 81% relative reduction in the need for further major surgery.

Osteoarthritis subgroup

A prospective analysis of the osteoarthritis subpopulation (Kon et al., AJSM, 2021) confirmed that Agili-C produced equivalent outcomes in patients with Kellgren-Lawrence Grade 1–3 arthritis and in patients without arthritis. This is the evidence underpinning the unique FDA indication for this population.

FDA approval and coding

Agili-C received FDA premarket approval (PMA P210034) on March 29, 2022, following a Breakthrough Device Designation. The AMA has established a Category I CPT code for the procedure effective January 1, 2027. Category I status, as opposed to a Category III "emerging technology" code, reflects mainstream clinical acceptance and improves insurance coverage prospects.

Who is a candidate?

FDA-Approved Indications

Per PMA P210034, Agili-C is indicated for:

• Symptomatic ICRS Grade III or IV cartilage or osteochondral defects of the femoral condyle or trochlea
• Total treatable lesion area of 1–7 cm² — a single defect, or the combined area of up to three defects treated in the same operation
• Kellgren-Lawrence Grade 0–3, including mild-to-moderate osteoarthritis. This is an indication no other cartilage restoration device carries
• Skeletally mature adults; the pivotal trial enrolled patients aged 18–75
• Normal or correctable lower-extremity alignment — malalignment must be corrected at the same or a prior operation
• A stable or reconstructed ligamentous environment

Lesion Location

The FDA indication covers the femoral condyle and trochlea. The patella and tibial plateau were not studied in the pivotal trial and are not within the approved indication. Your surgeon will review your MRI to confirm whether your lesion qualifies.

Contraindications

• Kellgren-Lawrence Grade 4 (bone-on-bone, end-stage arthritis) — knee replacement is the appropriate treatment
• Inflammatory arthritis (rheumatoid, psoriatic)
• Active joint infection, or a significant history of joint infection
• Severe malalignment that is not being corrected
• BMI over 40 — a relative contraindication, assessed case by case
• Significant meniscal deficiency in the operative compartment without planned meniscal allograft transplantation
• A prior failed cartilage procedure in the same compartment — a relative contraindication
• Inability to comply with the post-operative weight-bearing and rehabilitation protocol

The procedure

What Is the CARTIHEAL Agili-C Implant?

Articular cartilage has almost no capacity to heal itself. Full-thickness defects (from an acute injury, repetitive loading, osteochondritis dissecans, or early arthritis) cause pain, swelling, and mechanical symptoms, and left untreated they accelerate degeneration of the joint. Patients who already had arthritis were, until recently, excluded from cartilage restoration altogether.

CARTIHEAL Agili-C (CartiHeal Ltd., now part of Smith+Nephew) is an off-the-shelf, cell-free, biphasic aragonite scaffold that regenerates the articular cartilage and the subchondral bone beneath it in a single operation. It received FDA approval on March 29, 2022 (PMA P210034) and is the first and only FDA-approved cartilage repair device indicated for patients with coexisting mild-to-moderate knee osteoarthritis.

How Agili-C Works

The implant has two layers. The upper, cartilage layer is an aragonite (calcium carbonate) scaffold with a porous microarchitecture that recruits the patient's own mesenchymal stem cells and progenitor cells from the surrounding joint. Those cells differentiate into chondrocytes and lay down type II collagen (the hallmark of hyaline-like cartilage) while the aragonite gradually dissolves and the new tissue takes over the load.

The lower, bone layer is a denser aragonite structure that integrates directly with native subchondral bone by osseointegration. No bone graft and no cement are required. Treating both layers addresses the whole osteochondral unit rather than the cartilage surface alone.

Because the implant requires no cell harvesting, no staging, and no laboratory processing, it is available from inventory on the day of surgery. This is a practical advantage over cell-based therapies such as MACI, which need a three-to-six-week manufacturing lead time.

How Agili-C Compares to Other Cartilage Procedures

• Number of operations: Agili-C, microfracture, and OATS are each done in a single operation. MACI requires two: a biopsy, then a six-week cell culture, then implantation.
• Availability: Agili-C is off the shelf. MACI requires cultured cells; OATS requires harvesting cartilage plugs from the patient's own knee.
• Tissue produced: microfracture fills the defect with fibrocartilage (type I collagen). Agili-C and MACI produce hyaline-like tissue (type II collagen). OATS transplants true hyaline cartilage.
• Subchondral bone: Agili-C and OATS restore the bone beneath the cartilage. Microfracture and MACI address the cartilage layer only.
• Arthritis: Agili-C is the only one of these approved for patients with mild-to-moderate osteoarthritis (Kellgren-Lawrence Grade 1–3).
• Defect size: Agili-C treats a total lesion area of 1–7 cm², compared with under 2 cm² for microfracture, 1–4 cm² for OATS, and 2–10 cm² for MACI.

The most important of these is the arthritis indication. Agili-C is the first FDA-approved cartilage restoration device shown to produce equivalent outcomes in patients with and without coexisting mild-to-moderate osteoarthritis, which opens cartilage repair to an entirely new group of patients.

What Happens During the Procedure?

Preoperative Planning

A cartilage-specific MRI characterizes the defect: its size, depth, and location, and the condition of the surrounding bone and cartilage. Standing weight-bearing X-rays establish alignment, joint space, and Kellgren-Lawrence grade. Implant sizing is planned in advance; Agili-C is supplied in a range of cylindrical sizes.

Surgical Technique

The procedure is performed as outpatient surgery under general or spinal anesthesia and takes 60 to 90 minutes, including any concurrent procedures.

Step 1: Diagnostic arthroscopy. Standard arthroscopic portals are established. The joint is inspected to confirm the defect, assess the meniscus and ligaments, and identify any other pathology to be addressed.

Step 2 — Exposure. A small, targeted arthrotomy is made over the lesion. Direct visualization — rather than a purely arthroscopic approach — is what allows the defect to be prepared and the implant seated precisely.

Step 3: Defect preparation. Damaged cartilage and the calcified cartilage layer beneath it are debrided back to stable borders. The subchondral bone bed is prepared with a curette or burr to a controlled depth. Perpendicular walls and a flat base are essential for a secure press fit.

Step 4: Sizing. The prepared defect is measured with the Agili-C instruments, and one or more implants are selected to cover the full lesion and match the depth of the bed. Defects that need more than one implant are covered in a mosaic pattern.

Step 5 — Implantation. The implants are press-fit into the prepared bed with a dedicated insertion instrument and seated flush with the surrounding cartilage surface — neither proud nor recessed. No sutures, anchors, glue, or hardware are used; the press fit and the scaffold architecture provide the fixation.

Step 6: Confirmation and closure. Seating is confirmed arthroscopically and by direct visualization. The joint is irrigated, the arthrotomy and portals are closed in layers, and a compressive dressing is applied.

Concurrent Procedures

Malalignment, meniscal tears, and ligamentous insufficiency are addressed in the same operative setting whenever possible: high tibial osteotomy, meniscal allograft transplantation, or ligament reconstruction. Correcting the mechanical environment at the time of cartilage restoration protects the implant and is central to its durability.

Recovery timeline

Frequently Asked Questions

Meet the surgeons

Christopher S. Raffo, MD

Orthopedic Surgery · Sports Medicine · Knee & Shoulder Arthroscopy · Joint Replacement

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John J. Christoforetti, MD

Orthopedic Surgery · Sports Medicine · Hip, Knee & Shoulder Arthroscopy · Shoulder Replacement

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