Arthroscopic cartilage repair and transplantation restores damaged articular cartilage of the knee using a range of techniques selected by defect size, location, and depth. The procedure addresses focal cartilage injuries that produce pain, mechanical symptoms, and progressive joint damage if left untreated. Dr. Chudik selects from microfracture, osteochondral autograft transfer (OATS), osteochondral allograft transplantation, and matrix-assisted techniques depending on the specific defect and patient factors.
What Is Arthroscopic Cartilage Repair and Transplantation?
The articular cartilage of the knee covers the ends of the femur and the top surface of the tibia, with a separate layer on the undersurface of the patella. When cartilage is damaged, the underlying bone is exposed to higher contact stresses, and the defect tends to enlarge over time. Cartilage has limited ability to repair itself.
Surgical cartilage procedures are selected based on defect characteristics:
- Microfracture: small awl perforations in the subchondral bone stimulate marrow elements to produce fibrocartilage. Used for small defects (less than 2 cm²).
- Osteochondral Autograft Transfer (OATS): cylindrical plugs of cartilage and bone are taken from a less-loaded area of the same knee and transferred into the defect. Used for small to medium defects.
- Osteochondral Allograft Transplantation: a sized plug of donor cartilage with underlying bone is implanted into the defect. Used for larger defects, post-traumatic defects, and revision cartilage cases.
- Autologous Chondrocyte Implantation (ACI) and matrix-assisted techniques: harvested cartilage cells are cultured and re-implanted in a second-stage procedure. Used for selected larger defects in younger patients.
Who Is a Candidate?
Candidates for cartilage repair or transplantation typically have:
- Symptomatic focal cartilage defects on MRI
- Pain, catching, or progressive symptoms not controlled by non-surgical treatment
- Adequate surrounding cartilage and joint alignment
- Stable knee with functional ligaments (or planned simultaneous ligament reconstruction)
- Younger active patients for whom cartilage preservation matters long-term
Patients with diffuse arthritis or established advanced cartilage loss are typically better served by other procedures (partial or total knee replacement). Patients with malalignment that loads the defect compartment may need concomitant osteotomy.
How the Procedure Is Performed
The procedure is performed arthroscopically through standard portals. The cartilage defect is identified, debrided of unstable cartilage flaps, and measured.
For microfracture, an awl makes small holes through the subchondral bone plate. Marrow elements migrate through these holes and form a fibrin clot that gradually transforms into fibrocartilage.
For OATS, a cylindrical plug of healthy cartilage and underlying bone is harvested from a non-weight-bearing area. The recipient site is prepared with a matching cylindrical hole. The autograft plug is press-fit into the recipient site.
For osteochondral allograft, a sized plug of donor cartilage and bone is implanted into a precision-prepared recipient site. Larger defects may require multiple plugs or a single larger graft.
For ACI and matrix-assisted techniques, a first procedure harvests cartilage cells from a non-weight-bearing area. The cells are cultured for several weeks. A second procedure implants the cultured cells into the defect, often with a matrix scaffold.
Recovery and Rehabilitation
Recovery depends on the procedure:
- Microfracture: protected weight-bearing for six to eight weeks, return to sport at four to six months
- OATS: similar protected weight-bearing initially, return to sport at six months
- Osteochondral allograft: protected weight-bearing for six to eight weeks, return to sport at six to nine months
- ACI and matrix-assisted: longer recovery, return to sport at nine to 12 months
Risks and Outcomes
Risks include graft failure, persistent pain, infection, and progression to arthritis despite repair. Outcomes for focal cartilage procedures are best when the defect is identified and treated early. Concomitant alignment correction, ligament reconstruction, or meniscus preservation, when needed, improves outcomes.
Microfracture produces fibrocartilage, which is mechanically inferior to native hyaline cartilage but adequate for many smaller defects. OATS, allograft, and ACI restore hyaline-like cartilage but require larger procedures and longer recovery.
Why Dr. Chudik for Arthroscopic Cartilage Repair and Transplantation
Dr. Chudik treats the full spectrum of cartilage pathology and selects the technique based on defect size, location, depth, and patient factors. His joint preservation approach often combines cartilage procedures with concomitant ligament, meniscus, or alignment procedures to address all the factors driving the cartilage loss in a single operation when feasible.