Cartilage Repair and Transplantation (ACI, OATS)


What is an articular cartilage defect in the shoulder?

Articular cartilage is the shiny, white surface that covers the ends of most bones and protects them during movement by allowing the joint surfaces to glide smoothly with less friction. Articular cartilage defects (also known as a chondral injuries) are typically found in patients with shoulder trauma, recurrent instability and dislocations, or previous surgical treatment. 

Chondral defects are graded from mild to severe:

  • Grade 1 – The cartilage becomes soft in the earliest form of damage
  • Grades 2 and 3 – As the condition worsens, the cartilage may develop a shredded appearance. The grade of injury depends on the size and thickness of the defect
  • Grade 4 – The cartilage may wear away completely, leaving the underlying bone exposed.


How do I know if I need surgery? 

The treatment of chondral damage in the shoulder typically depends on the specific location, size of the defect, severity of patient symptoms, and coexisting pathology within the shoulder. In certain cases, non-operative treatment may be beneficial for patients with mild symptoms or in those whose MRI shows only mild softening of the cartilage surface without any large defects. However, if severe chondral injuries are left untreated, it can eventually hinder your ability to move free from pain and cause irreversible joint damage.

What types of surgery are available for articular cartilage injuries?

In the past decade, there have been many exciting advances in the surgical treatment of articular cartilage defects. Dr. Potts utilizes the most advanced surgical techniques for cartilage repair in order to provide his patients with the best results possible. The procedure chosen varies greatly on the location and overall size of the defect. The most commonly performed procedures for treating chondral defects in the shoulder include: 

  • Microfracture – During this arthroscopic procedure, the base of the damaged area is scraped to create a bleeding bed of bone, and then small holes are created in the subchondral bone to allow healing cells to flow into the defect and stimulate fibrocartilage formation. Microfracture is usually reserved for patients with small symptomatic defects or in those who are less active.
  • Autologous Chondrocyte Implantation (ACI) – This is a two-step procedure where articular cartilage is biopsied from the patient during the initial arthroscopy and sent to a lab where the chondrocytes (cartilage cells) are processed and grown. After a growth period of around 1 month, the cells are then re-implanted into the cartilage defect to facilitate healing.
  • Osteochondral Allograft Transfer (OATS) – If a cartilage defect is too large for an autograft, an allograft is usually considered. Defects that occur with injuries such as fracture-dislocations or engaging Hill-Sachs lesions are ideal lesions for this procedure, especially when the patient is experiencing persistent instability despite standard stabilization techniques. The allograft is fresh cartilage and bone from a donor, and can be shaped to fit the exact contour of the defect and then fit into place. Allografts are typically done through an open incision, and available instruments can create grafts between 10 and 35 mm in diameter. First, the defect is exposed and sized. A guide pin is then placed through the center of the lesion, and depth measurements are taken from the prepared recipient site. The allograft plug is then marked with the recipient depth measurements. Excess bone is removed from the graft in order to match the defect’s size and shape, and then the graft is inserted to fill the defect.