Sub-Specialty Hub
Single-stage structural cartilage-and-bone replacement for full-thickness osteochondral defects of the knee — OATS for small focal defects, osteochondral allograft (OCA) for large or bone-involved defects, and CartiHEAL Agili-C aragonite scaffold as a single-stage cell-free option. Performed by Dr. Sabrina Strickland at the Hospital for Special Surgery in New York. The structural option for defects MACI cannot cover.
Cartilage transplant is the family of single-stage knee procedures that physically replace cartilage AND the underlying bone in a focal defect. Three options: OATS (osteochondral autograft transfer) — native cartilage-and-bone plugs from the patient's own knee, ideal for small focal defects under 2 cm². Osteochondral allograft (OCA) — fresh size-matched cadaveric tissue, ideal for defects typically over 2 cm², bipolar lesions, OCD with subchondral bone loss, and revision cartilage surgery. CartiHEAL Agili-C — an FDA-approved (2022) cell-free aragonite-hyaluronate scaffold that supports regeneration of cartilage and bone over 12 to 24 months. Distinct from MACI, which is a two-stage cell-based repair of the cartilage layer only and depends on a healthy underlying bone. When the bone is involved — OCD lesions, post-traumatic craters, AVN-related collapse, or after prior microfracture has produced subchondral sclerosis — transplant is the right choice. CartiHEAL now has a Category I CPT code effective January 1, 2027. Dr. Sabrina Strickland performs all three at the Hospital for Special Surgery and has published research on bone marrow edema as a predictor of OCA failure.
If your MRI shows a cartilage defect with subchondral bone involvement — an OCD lesion, a post-traumatic crater with bone loss, an AVN-related condylar collapse, or a previously-microfractured site that has gone on to develop bone irregularity — cell-based repair like MACI alone is not enough. The cell-loaded membrane has nothing structural to sit on. Cartilage transplant procedures replace both layers in a single operation: the cartilage you see and the bone underneath that you cannot.
This page is the sub-specialty hub for cartilage transplantation. It pairs with the MACI cartilage repair page — together the two pages cover the cartilage-restoration menu as a decision hub. Use this page when bone is involved, when the defect is large, when prior cartilage surgery has failed, or when a single-stage operation is preferred over the two-stage MACI protocol. Topics covered: when transplant is the right call (and when it is not), the three transplant procedures in detail, how they compare to MACI, lesion-size based decision-making, Dr. Strickland's published research on bone marrow edema as an OCA failure predictor, concurrent realignment / ligament / meniscus procedures, prehabilitation, the surgical day, the long maturation interval (especially for CartiHEAL), risks specific to each transplant type, common patient concerns, insurance and the new CartiHEAL CPT code, emerging single-stage options, and access to consultation in NYC and Stamford, CT.
Articular cartilage does not heal itself. There are no blood vessels in cartilage and the cells inside it (chondrocytes) cannot migrate to a wound to repair it. A full-thickness defect — a hole through the cartilage layer to the underlying bone — will not fill in on its own. The cartilage-restoration field is built around different ways to fill that non-healing hole. The decision about which way to fill it depends on what the defect actually is, and specifically whether the underlying bone is involved.
Cell-based repair (microfracture, MACI) is built on the assumption that the bone underneath the defect is structurally healthy — a stable platform for the new cartilage to grow on. That assumption breaks down in several common scenarios:
In each of these scenarios, a structural transplant — OATS, OCA, or CartiHEAL — is the better answer because it replaces or rebuilds the bone foundation at the same time as the cartilage. The MACI page and this page together cover the menu: chondral-only defect with healthy underlying bone → MACI is often the right call; osteochondral defect with bone involvement → transplant is the right call. Dr. Strickland's clinical comparison of CartiHEAL, OCA, and MACI frames this directly: there is significant overlap in indications, but the bone is what tips the decision toward transplant.
The three transplant options share a single-stage workflow and the principle of replacing or regenerating both cartilage and bone — but they differ meaningfully in donor source, defect-size sweet spot, and biology.
Plug of native cartilage + bone from the patient's own non-weight-bearing knee surface. Best for small focal defects (under 2 cm²). Single-stage, no waiting.
Fresh size-matched cadaveric osteochondral graft. Best for large defects (over 2 cm²), bipolar lesions, OCD with bone loss, and revision cartilage cases.
FDA-approved (2022) aragonite-hyaluronate scaffold. Off-the-shelf, single-stage. The scaffold resorbs over 12 to 24 months as native tissue replaces it.
All three are performed at HSS by Dr. Strickland. The discussion below covers each in detail, then how they compare to one another and to MACI.
OATS — Osteochondral Autograft Transfer System — is the cartilage transplant that uses your own tissue. With a small mini-arthrotomy for access, one or more cylindrical plugs of cartilage with attached subchondral bone are harvested from a non-weight-bearing donor area of the same knee — typically the edge of the trochlea or the intercondylar notch — and press-fit flush into a precisely-sized recipient socket prepared at the defect. The transferred cartilage is true native hyaline cartilage, identical to what was there originally because it is what was there originally, just relocated. The multi-plug variant for slightly larger or non-round defects is called mosaicplasty.
The classic OATS candidate is a younger active patient with a small focal full-thickness osteochondral defect (typically under 2 cm²), most commonly on the medial or lateral femoral condyle, with stable ligaments, correct alignment, a functional meniscus, BMI under 35, and willingness to do a structured rehab. OATS is also reasonable for some small focal trochlear lesions when an autograft donor site can be identified that does not compromise the patellofemoral mechanics.
Osteochondral allograft — OCA, also called fresh osteochondral allograft (FOCA) — uses a fresh size-matched cadaveric osteochondral graft (cartilage with attached subchondral bone) recovered from a tissue-donor knee within the fresh-graft viability window. The graft is shaped to match the recipient defect (single-plug, multi-plug, or larger dowel/shell technique) and press-fit with the cartilage surface flush to the surrounding articular surface. OCA replaces both cartilage and bone in one operation, has no inherent size limit, and is the preferred choice for the lesions cell-based repair and OATS cannot adequately handle.
MACI restores cartilage but does nothing structural for the bone underneath. When a defect involves significant subchondral bone loss — an OCD lesion with subchondral collapse, a post-traumatic crater, AVN-related condylar bone death, or a knee that has had failed prior microfracture leaving sclerosis and cysts — MACI alone will not work. The cell-loaded membrane needs a stable structural platform. OCA replaces both the cartilage and the bone in a single stage. For very large defects (over 4 cm² and especially over 6 cm²) or for bipolar (kissing) lesions on opposing surfaces of the same compartment, OCA also avoids the donor-site limit of OATS. It is the structural option for defects MACI cannot cover.
OCA availability and matching introduce a wait time — fresh osteochondral grafts are scheduled around tissue-bank availability and patient-graft size matching, including precise condylar measurements and laterality. Our office coordinates the timing. Dr. Strickland's research on the topic includes a study on single vs. multiple plug OCA transplants and how Wiberg patellar type impacts outcomes and survival.
CartiHEAL Agili-C is the newest of the three options and represents a different concept: instead of transferring native cartilage tissue, it implants a biomaterial scaffold that supports the body's own regeneration of cartilage and bone. The Agili-C implant is a dual-phase porous scaffold made from aragonite (calcium carbonate derived from coral) with a hyaluronate surface layer. It is press-fit into a prepared cylindrical defect during a single operation. Over the following 12 to 24 months, the scaffold gradually resorbs as the body lays down native cartilage in the upper layer and native bone in the lower layer in its place.
Dr. Strickland was an early adopter when CartiHEAL relaunched after the 2022 FDA approval — she has performed CartiHEAL in 35 to 40 patients to date, including multi-compartment cases and one-step cartilage repair of trochlear lesions (see CartiHEAL for trochlear lesions). Her view, expressed in the VuMedi discussion with Dr. Andreas Gomoll: CartiHEAL gives her a slightly lower threshold to treat certain defects that did not have a great answer in the past — particularly narrow central trochlear lesions with bone edema and smaller condylar lesions in patients with multi-lesion early arthritis. Patients in those categories are often the most satisfied because they did not previously have a surgical option short of arthroplasty.
Patients with focal cartilage or shallow osteochondral defects of the knee — typically 1 to 7 cm² — in patients who want a single-stage procedure with no waiting for cell culture and no donor-site morbidity. Particularly useful for narrow central trochlear lesions, smaller condylar lesions with associated bone edema, and patients with multi-lesion patterns and early arthritis. As with all cartilage restoration, alignment, ligament stability, and meniscal function need to be addressed (in the same operation when needed) for the implant to succeed.
The fundamental decision in cartilage restoration is single-stage transplant (OATS, OCA, CartiHEAL) versus two-stage cell-based repair (MACI). The right answer depends on lesion size, depth, the state of the underlying subchondral bone, prior cartilage surgery, and how willing the patient is to commit to either workflow.
| Defect size | Bone involvement | Stages | Cartilage type | Recovery | |
|---|---|---|---|---|---|
| OATS | Small (under 2 cm²) | Yes (cartilage + bone) | Single | Native hyaline (transferred) | 6–9 months |
| Osteochondral allograft | Large (over 2 cm²) | Yes (cartilage + bone) | Single | Native hyaline (donor) | 9–12 months |
| CartiHEAL Agili-C | Medium (1–7 cm²) | Shallow bone OK | Single | Regenerated native | 6–9 months |
| MACI | Medium-large (2–10 cm²) | No (chondral only) | Two (4–6 wk apart) | Hyaline-like (cell-grown) | 12–18 months |
Dr. Strickland's clinical comparison of CartiHEAL, OCA, and MACI reinforces that there is significant overlap in indications. The decision is not algorithmic; it is lesion-by-lesion. A focal 5 cm² defect in a 32-year-old with a healthy underlying bone bed could reasonably be treated with MACI, OCA, or CartiHEAL — and the right answer depends on imaging detail, prior surgical history, the state of the rest of the joint, and the patient's appetite for two operations versus one. Two MRIs that look similar to a non-specialist can lead to different operations in a sub-specialty practice because of these contextual factors. Dr. Strickland's published outcomes review of multi-surface cartilage restoration procedures provides the framework she uses for these decisions.
One of Dr. Strickland's specific contributions to the cartilage-transplantation literature is a refinement of how we follow OCA patients on post-operative MRI. Some bone marrow edema (BME) in the host bone surrounding an osteochondral allograft is expected during the bone-integration phase — the donor bone is being remodeled and replaced by host bone, and that biology produces a signal change on MRI. The clinical question her group asked: does the volume of BME on the routine 6-month post-operative MRI predict subsequent graft failure?
Strickland et al. studied 56 patients (mean age ~32) with at least 2-year follow-up after osteochondral allograft transplantation. Patients were divided by BME volume on the 6-month post-operative MRI: BME ≥ 10 cm³ vs. BME < 10 cm³.
Result: all of the OCA failures in the study cohort occurred in the BME ≥ 10 cm³ group, representing a 50% subsequent failure rate in that group. Patients with BME < 10 cm³ had no failures.
Published in Arthroscopy: The Journal of Arthroscopic and Related Surgery, 2024. See commentary on the study and increased host bone marrow edema as a risk factor for OCA failure.
It changes how we use the 6-month MRI. Routine post-operative imaging is no longer just confirmation that the graft is in place; the BME volume on that scan is a meaningful checkpoint. Patients with high host BME at 6 months are a higher-risk group, and that information can inform decisions about activity progression, additional imaging at 12 months, biologic augmentation, or earlier intervention. The study does not yet tell us how to change outcomes in the high-BME group — that is the next research question — but it gives us imaging-based data that predicts failure rather than waiting until clinical symptoms recur. This is part of why Dr. Strickland's OCA follow-up protocol includes a 6-month MRI as a defined checkpoint.
This is one of the most under-explained ideas in cartilage transplantation: cartilage transplant in a malaligned, unstable, or meniscus-deficient knee will not last. The same forces that destroyed the original cartilage will destroy the transplant, often within a few years. The cartilage decision is rarely just "what to do at the defect." It is "what does the rest of the knee need so the transplant can succeed." The relevant combinations:
These combinations are common, not rare. A meaningful percentage of cartilage-transplant patients in Dr. Strickland's practice have at least one concurrent procedure, often planned at the same operation. See joint preservation and osteotomy for the realignment side of the plan. For the patellofemoral version of this principle, see patellar instability, MPFL reconstruction surgery, and patellar pain and patellofemoral arthritis.
Patients who walk into a cartilage-transplant operation with a strong quadriceps, full range of motion, and no effusion recover faster and meet rehabilitation milestones more reliably than patients who walk in with a stiff, weak, swollen knee. The peri-operative prehabilitation focus:
Cold-compression devices and quadriceps muscle stimulators (when prescribed) help reduce swelling and support muscle reactivation in the first weeks.
Cartilage transplant recovery depends on the specific procedure and on whether bone is being incorporated. The slowest-healing tissue drives the timeline — for OATS and CartiHEAL, that is the cartilage-bone integration; for OCA, it is the donor-bone-to-host-bone integration, which is the longest of the three. For patients used to thinking about MACI (12 to 18 months for cartilage maturation), OCA's 9-to-12-month return-to-sport is faster than MACI but still substantial. OATS and CartiHEAL are the fastest at 6 to 9 months. Concurrent osteotomy or ligament reconstruction can extend the timeline.
| Phase | OATS | OCA | CartiHEAL |
|---|---|---|---|
| Protected weight-bearing | 4 weeks | 4 weeks | 4 weeks |
| Off crutches (gradual) | Week 6 | Week 6 | Week 6 |
| Strengthening + low-impact cardio | Months 2–4 | Months 2–4 | Months 2–4 |
| Routine 6-month MRI checkpoint | If indicated | Standard (BME assessment) | Standard |
| Return to running | Months 4–6 | Months 6–9 | Months 6–9 |
| Return to pivot/contact sport | Months 6–9 | Months 9–12 | Months 6–9 |
| Continued maturation | Months 6–12 | Months 12–24 (bone integration) | Months 12–24 (scaffold resorption) |
For OCA specifically, the 6-month MRI is not just a check on the graft — it is an active part of decision-making, given Dr. Strickland's published BME findings. If concurrent osteotomy is performed, recovery follows the longer of the two protocols (osteotomy timeline). If MPFL or other ligament reconstruction is performed at the same time, the ligament protocol drives the early phases. For long-term outcomes data on the single-stage approach, see her long-term outcomes study of one-step cartilage repair.
Across all three procedures, the two factors that most consistently slow recovery are inconsistent physical therapy attendance and rushing back to high-impact activity before clearance. The patients who do well with cartilage transplant are the patients who treat the rehab as seriously as the surgery.
Cartilage transplantation has a long published track record — OCA in particular has decades of clinical experience. Outcomes in well-selected patients are generally favorable, but no surgery is risk-free. Risks reviewed at consultation include:
The single biggest predictor of a poor outcome is patient selection. The second is failing to address concurrent problems (alignment, ligament, meniscus) at the time of the cartilage transplant. When the conditions line up and the patient does the rehab, cartilage transplantation is one of the more successful joint-preserving operations in orthopedics today.
The friction-log: the four concerns we hear most often from patients considering cartilage transplantation, with honest answers.
Fresh osteochondral allografts come from carefully screened tissue donors and are tested rigorously by tissue banks before release for surgery. Disease transmission is extremely rare with modern screening. Allograft cartilage is also relatively immune-privileged — cartilage cells (chondrocytes) are buried in their matrix and are not exposed to the recipient's immune system the way other transplanted tissues are. The bone fraction does undergo remodeling and replacement by your own bone over time. Patients have been receiving fresh osteochondral allografts for decades; the safety profile is well established. If allograft is not the right fit for you, OATS (your own tissue) and CartiHEAL (a synthetic scaffold) are the alternatives.
For active patients in their 30s, 40s, and even 50s with focal full-thickness damage and otherwise reasonable joint health, a partial or total knee replacement commits you to a revision conversation in your lifetime — modern implants do not last forever, and revision arthroplasty is more complex than primary. Cartilage transplant, when feasible, restores the joint surface without an implant and preserves the option to do a replacement later if needed. This is the framework Dr. Strickland describes in "Why I Would Rather Repair Cartilage Than Replace a Knee." Replacement is the right answer for the right patient — the 65-year-old with bone-on-bone multi-compartment arthritis is a unicompartmental or total knee candidate, not a cartilage-transplant candidate. The cartilage-first framework is about identifying the patients for whom transplant is technically feasible and biologically appropriate.
Lesion size by itself does not disqualify cartilage transplant. The size cap on OATS is real (donor-site availability) but allograft has no inherent size limit. Some of Dr. Strickland's largest single-compartment OCA cases — for OCD with extensive bone loss, post-traumatic craters, or revision after multiple failed prior repairs — would not have been candidates for any other cartilage operation. The right question is not how big the defect is, but whether the rest of the joint can support a graft. If the alignment, ligaments, and the opposing surface in the same compartment are in reasonable shape, allograft is often feasible even for large defects. Bringing your imaging in for a sub-specialty review is the right step before accepting "you need a replacement."
No. Failed prior microfracture is one of the more common reasons patients are referred for cartilage transplantation. Microfracture changes the biology of the bone underneath the defect — it can become sclerotic, irregular, or develop intralesional cysts — and that altered bone bed compromises a subsequent cell-based repair like MACI. In many of these revision scenarios, osteochondral allograft (OCA) is the more durable choice because it replaces both the disrupted bone and the cartilage in one stage. CartiHEAL can also be a strong option for some shallower failed-microfracture patterns. Imaging review (MRI with cartilage sequences, sometimes a CT to characterize subchondral bone) is the first step. Failed microfracture is not a closed door — it changes the menu of options and the operative plan.
OATS and osteochondral allograft are well-established, FDA-cleared procedures. CartiHEAL Agili-C is FDA-approved (2022) and has reached a significant milestone with the recent AMA Category I CPT code. Coverage and cost specifics:
Before surgery, our office verifies your benefits, obtains pre-authorization where required, and reviews the estimated out-of-pocket cost with you. For benefits verification or to discuss self-pay arrangements, call us at (646) 960-7227 or contact the office.
Cartilage transplantation is one of the most active fields in sports orthopedics. Emerging single-stage options Dr. Strickland evaluates, participates in, or discusses with patients include:
The cartilage-transplantation field is moving forward, and FDA-approved options will continue to expand. The current right-sized choices for full-thickness osteochondral defects of the knee are still OATS, OCA, and CartiHEAL; emerging options expand the menu rather than replace it. For the broader cartilage-restoration discussion including stem cells, exosomes, and orthobiologics, see the MACI page emerging-options section.
Cartilage transplantation is one of Dr. Strickland's primary clinical and academic areas. She performs the full menu of cartilage-restoration procedures (OATS, OCA, CartiHEAL, MACI) and routinely combines them with realignment osteotomy, MPFL reconstruction, ACL reconstruction, and meniscus surgery in the same operation when concurrent pathology demands it. She has published her own bone-marrow-edema-as-failure-predictor research on OCA, has co-hosted the AOSSM Sports Doc podcast on challenging cartilage injuries, and has co-authored technique papers on combined CartiHEAL plus unicompartmental arthroplasty for complex single-compartment cases.
A sub-specialty second opinion is particularly worth seeking when:
Cartilage decisions are complex because the right operation depends on lesion size and depth, location, alignment, ligament status, meniscus status, prior surgery, age, BMI, and patient activity goals. Two MRIs that look similar to a non-specialist can lead to different operations in a sub-specialty practice because of these contextual factors. A sub-specialty second opinion does not always change the recommendation — but it does ensure the recommendation is built on the right framework.
Dr. Strickland sees cartilage-transplant patients at two offices, both of which work with patients traveling in from outside the immediate area:
Many patients travel to New York for cartilage-transplant sub-specialty care — particularly for OCA candidacy evaluations, second opinions on prior failed cartilage surgery, complex combined cases (transplant plus osteotomy, MPFL, or meniscus work), and consultations on whether early joint replacement can be avoided. Surgery is performed at HSS. We coordinate consultation, imaging review, tissue-bank scheduling for OCA cases, and surgery scheduling to minimize travel for out-of-state patients.
Cartilage transplant is the family of single-stage knee procedures that physically replace cartilage — and almost always the underlying bone — in a focal defect, rather than growing new cartilage from cells. The three options Dr. Strickland performs at HSS: OATS uses native cartilage-and-bone plugs from the patient's own knee, ideal for small focal defects under 2 cm². Osteochondral allograft (OCA) uses fresh size-matched cadaveric tissue, ideal for large defects (often over 4 cm²), defects with significant subchondral bone loss, OCD lesions, and revision cartilage surgery. CartiHEAL Agili-C is a cell-free aragonite-hyaluronate scaffold (FDA-approved 2022) that supports regeneration of cartilage and bone in a single operation. All three are single-stage operations — distinct from MACI, which is a two-stage cell-based repair.
Two key differences. First, transplant is single-stage; MACI is two-stage with a 4-to-6-week cell-culture interval. Second, transplant restores cartilage AND bone (or in CartiHEAL's case, supports regeneration of both layers); MACI is a chondral-only repair that depends on a healthy underlying subchondral bone bed. When the bone is involved — OCD lesions, post-traumatic craters, AVN-related collapse, or after prior microfracture has produced sclerosis — MACI alone is not enough. The cell-loaded membrane has nothing structural to sit on. That is when transplant becomes the right choice.
OATS — Osteochondral Autograft Transfer System — uses your own tissue. Cylindrical plugs of cartilage with attached subchondral bone are harvested from a non-weight-bearing donor area of the same knee (typically the edge of the trochlea or the intercondylar notch) and press-fit flush into a precisely-prepared recipient socket at the defect. The transferred cartilage is true native hyaline. OATS is best for small focal defects (typically under 2 cm²) because of donor-site availability. The multi-plug variant is mosaicplasty. OATS is single-stage, requires no cell culture, no donor matching, and no waiting.
Osteochondral allograft (OCA) uses a fresh size-matched cadaveric osteochondral graft — cartilage with attached subchondral bone — recovered from a tissue-donor knee within the fresh-graft viability window. It is shaped to match the recipient defect and press-fit flush. OCA replaces both cartilage and bone in one operation and is the preferred choice for large defects (often over 4 cm²), bipolar lesions, OCD with bone loss, AVN-related collapse, and revision cartilage surgery. The trade-off is graft availability — OCAs are scheduled around tissue-bank availability and patient-graft size matching, which can introduce a wait time.
CartiHEAL Agili-C is an FDA-approved (2022) cell-free osteochondral implant made of porous aragonite (calcium carbonate derived from coral) with a hyaluronate surface layer. The dual-phase scaffold is press-fit into a prepared defect during a single operation. Over 12 to 24 months it gradually resorbs as the body lays down native cartilage in the upper layer and native bone in the lower layer. CartiHEAL is single-stage, off-the-shelf, and now has a Category I CPT code effective January 1, 2027. Dr. Strickland has used the implant in 35 to 40 patients to date and considers it strong for narrow central trochlear lesions, smaller condylar lesions with bone edema, and multi-lesion patients with early arthritis.
Lesion size, depth, location, the state of the underlying subchondral bone, prior cartilage surgery, alignment, ligament status, meniscus status, age, and activity goals all matter. Rough size-based framework: microfracture for small chondral defects under 2 cm² in low-demand patients; OATS for small focal osteochondral defects under 2 cm²; MACI for chondral-only defects 2 to 10 cm² without bone involvement; CartiHEAL for shallow osteochondral defects 1 to 7 cm²; OCA for large defects over 4 cm², bipolar lesions, OCD with bone loss, AVN-related collapse, and revision after failed prior cartilage surgery. The decision is made after MRI review, standing alignment films, and a discussion of your goals.
OATS: 4 to 6 weeks of protected weight-bearing, return to running at 4 to 6 months, return to pivot/contact sport at 6 to 9 months. OCA: 6 to 8 weeks of protected weight-bearing — longer because the donor bone has to integrate with the host bone — and return to pivot/contact sport at 9 to 12 months. CartiHEAL: 6 weeks protected weight-bearing, return to sport at 6 to 9 months as the scaffold resorbs and is replaced by native tissue over 12 to 24 months. Concurrent procedures extend the timeline. The constraint is the slowest-healing tissue, which for OCA is the bone-bone integration interface.
Bone marrow edema (BME) on MRI is increased water signal in the bone surrounding the graft. After OCA, some BME is expected during bone integration. Dr. Strickland's research, published in Arthroscopy: The Journal of Arthroscopic and Related Surgery (2024), looked at 56 patients with at least 2-year follow-up and found that patients with host BME volume ≥ 10 cm³ on the routine 6-month post-operative MRI had a 50% subsequent failure rate, while patients with BME < 10 cm³ had no failures. This refines how we follow OCA patients — the 6-month MRI is a meaningful checkpoint that can identify higher-risk patients.
Often, yes. The same forces that destroyed the original cartilage will destroy the transplant. If standing alignment films show varus or valgus malalignment, an osteotomy (HTO, DFO, or AMZ-TTO) is performed in the same operation to protect the transplant. Realigning the forces is what makes the transplant durable. MPFL reconstruction is added for patellar or trochlear transplants with patellar instability. Meniscus repair or transplant is added when the meniscus is compromised. ACL reconstruction is added for ACL-deficient knees. See joint preservation and osteotomy.
OATS and OCA are covered by most major commercial plans, Medicare, and many self-funded and union plans when medical-necessity criteria are met. CartiHEAL Agili-C is FDA-approved and now has a Category I CPT code from the AMA effective January 1, 2027 — a significant insurance milestone that streamlines the reimbursement pathway. Pre-authorization is still required and our office coordinates the documentation. Out-of-pocket cost depends on the plan deductible, coinsurance, and in-network status of the surgeon, facility, and anesthesia group. Verify your specific benefits before scheduling.
Failed prior microfracture is a common reason for cartilage-transplant referral. Microfracture changes the biology of the bone underneath the defect — it can become sclerotic, irregular, or develop intralesional cysts — and that altered bone bed compromises a subsequent cell-based repair. In many revision scenarios, OCA is the more durable choice because it replaces both the disrupted bone AND the cartilage in one stage. CartiHEAL can also be a strong option for some shallower failed-microfracture patterns. Imaging review is the first step.
Dr. Sabrina Strickland performs OATS, osteochondral allograft transplantation, and CartiHEAL Agili-C implantation at the Hospital for Special Surgery in New York City. HSS is the highest-volume orthopedic hospital in the United States and one of the institutions where cartilage transplant procedures are most commonly performed. Patients travel from New York, Connecticut, New Jersey, and across the region for cartilage-transplant candidacy evaluations and second opinions. Dr. Strickland also sees patients at her satellite office at Stamford Chelsea Piers in Stamford, CT for in-person consultation; surgery is performed at HSS.
This page is grounded in Dr. Strickland's published commentary, technical notes, follow-up studies, and patient education on cartilage transplantation and the broader cartilage-restoration field. Selected references:
For chondral-only defects in the medium-to-large range without bone involvement, see MACI cartilage repair — the pair page to this one. For the realignment side of cartilage protection (HTO, DFO, AMZ-TTO), see joint preservation and osteotomy. For patellar or trochlear cartilage lesions in the context of patellofemoral pain or arthritis, see patellar pain and patellofemoral arthritis. For patellar instability that contributed to patellar or trochlear cartilage damage, see patellar instability and MPFL reconstruction surgery. For ACL-deficient knees with cartilage damage, see ACL tear surgery. For meniscus-deficient compartments, see meniscal tear and torn meniscus. For multi-compartment knee arthritis where joint preservation is no longer feasible, see knee arthritis. For chondromalacia and tendonitis at the front of the knee, see knee chondromalacia, arthritis, and tendonitis. For complex anatomy where computer-guided planning is helpful, see Mako robotic-assisted surgery.
For Dr. Strickland's published research record on cartilage transplantation, OCA outcomes, and the broader cartilage-restoration field, the source-grounding table above lists the references used on this page; for the broader publication record, see research & publications.
Medical Disclaimer. This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Surgical and non-surgical orthopedic care should always be discussed with a board-certified orthopedic surgeon who has reviewed your imaging, history, and physical examination. Individual outcomes vary based on diagnosis, anatomy, comorbidities, surgical technique, concurrent procedures, and adherence to rehabilitation. OATS, osteochondral allograft (OCA), and CartiHEAL Agili-C are FDA-approved or FDA-cleared procedures for full-thickness osteochondral defects of the knee; outcomes in the published literature are favorable in well-selected patients but cartilage transplantation is not a guaranteed permanent fix and the long-term durability of the transplanted tissue varies with patient factors, alignment, ligament status, meniscus status, and concurrent care. The Hyalex knee cartilage system and amniotic suspension allograft (ASA) injections referenced on this page are investigational under FDA clinical-trial protocols. Volume figures, timelines, and outcome statements on this page are drawn from Dr. Strickland's published clinical and academic work, cited in the source-grounding table above, and from FDA labeling for the implants discussed.
If your MRI shows an osteochondral defect with bone involvement, an OCD lesion or post-traumatic crater, a defect too large for cell-based repair, a previously-failed cartilage repair, or you have been told you need early joint replacement and want to know whether your cartilage can be transplanted instead — bring your imaging to a sub-specialty consultation in NYC or Stamford, CT.
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