Penn Orthopaedics

Penn Cartilage Center

The Penn Center for Advanced Cartilage Repair and Osteochondritis Dissecans Treatment is one of only a few clinics across the nation dedicated to cartilage repair. It is one of the first to focus on osteochondritis dissecans (OCD), a rare and often misunderstood condition in which a fragment of bone and cartilage separates causing pain, swelling and mechanical issues. This condition occurs most commonly in the knee.

The purpose of the Penn Cartilage Center is to facilitate collaboration between national leaders in cartilage research and to act as a location that houses interdisciplinary research, linking basic science, translational studies and clinical research. An emphasis is placed on optimal personalized treatment plans through integration of the best available evidence into the shared decision- making process.

Conditions and Treatments

In addition to the treatment of osteochondritis dissecans, the Penn Cartilage Center also offers treatment for severe cartilage problems with procedures including:

Autologous Chondrocyte Implantation (ACI)

ACI is most effective in younger patients who have single defects larger than 2 cm in diameter. This two-step procedure involves new cartilage cells being grown and then implanted in the cartilage defect. Healthy cartilage tissue is removed from a non-weight bearing area of the bone. The cells from the tissue are then cultured and increased over the next month.

An arthrotomy is then performed to implant the newly grown cells and a collegan cover or a layer of bone-lining tissue, called periosteum, is sewn over the cartilage defect.

  • Six to eight weeks before implantation, some of the patient's own healthy cartilage cells are harvested and sent to a lab where millions more cells are grown.

  • James L. Carey, MD, MPH is among the nation's leaders in ACI. Here, Dr. Carey and physician's assistant Sabrina Fitzig scrub in and discuss preparations for surgery.

  • Before the initial incision, Dr. Carey examines the cartilage and other structures in the knee using minimally invasive arthroscopy.

  • After opening the knee, ACI requires intense precision during the preparation of the damaged area where the new cells will be implanted.

  • Before the new cells are implanted, Dr. Carey sizes and places a special cover over the defect to hold the new cells in place.

  • Before the new cells are implanted, Dr. Carey sizes and places a special cover over the defect to hold the new cells in place.

  • Dr. Carey injects the new cartilage cells under the cover where they will change from a liquid when injected to fully assimilate with cartilage by 1 year post-surgery.

  • Dr. Carey talks the patient's father post-surgery, detailing the success of the procedure and outlining the rehabilitation schedule.

Osteochondral Autograft Transfer (OAT)

An osteochondral autograft transplantation, used for smaller cartilage defects, is when cartilage - a graft - from one part of the joint is transferred to another. The healthy cartilage is taken from an area of the bone that is non-weight bearing. The graft is then matched to the surface area of the defect and impacted in place, leaving a smooth surface in the joint.

Osteochondral Allograft Transplantation

A good candidate for an osteochondral allograft transplantation is a younger, more active individual with a symptomatic, disabling cartilage injury or disease present in the knee, ankle or other joints, such as the shoulder. An allograft is a tissue graft taken from a cadaver donor. Similar to, but larger than, an autograft, it is a block of cartilage and bone that can be shaped to fit the exact contour of the defect and then press fit into place.

Allografts are usually done through an open incision.


The goal of microfracture is to stimulate the growth of new articular cartilage by creating a new blood supply. This is achieved by making multiple holes in the joint surface to stimulate a healing response. Marrow elements reach the joint surface and bring new cells that form the new cartilage.

The best candidates are young patients with single lesions and healthy subchondral bone. This procedure can be done arthroscopically.

Meniscal Transplantation

A meniscal transplant replaces the damaged meniscus with a new meniscus from a cadaver donor. The new meniscus provides support and acts as a shock absorber. This procedure, which can help knee pain and possibly prevent arthritis, is only performed in cases when most of the meniscus cartilage must be removed.



Clinical Faculty

Research Support Staff

  • Bioengineering (Materials and Constructs):
    Robert L. Mauck, PhD; Associate Director for Research
    Jason A. Burdick, PhD
  • Cell and Developmental Biology:
    George R. Dodge, PhD
    Maurizio Pacifici, PhD
  • Novel Imaging and Diagnostics:
    K. Rajender Reddy, MD, PhD
  • Model Development and Pre-Clinical Translation:
    Thomas P. Schaer, VMD
    Dean W. Richardson, DVM

Patient Coordinator

  • Sabrina Fitzig, MS, PA-C
    Physician Assistant