June 11, 2026
Articular cartilage injuries are a frequent challenge in sports medicine, particularly among athletes exposed to high-velocity twisting, pivoting and rotational forces. These stresses increase the likelihood of focal cartilage defects — areas that Craig H. Bennett, M.D., orthopedic surgeon at Mayo Clinic in Minnesota and team physician for the Minnesota Timberwolves, says can resemble "a pothole in what was previously normal cartilage."
Because articular cartilage has minimal regenerative capacity, even small defects can compromise joint mechanics and long-term function. According to Dr. Bennett, "the knee requires a change of environment to return to a functional extremity" when the body cannot restore cartilage on its own.
Why early evaluation matters
Although some defects may stabilize, Dr. Bennett emphasizes that they do not resolve spontaneously.
"Untreated, the deficiency will remain and often progress," he says.
Dr. Bennett encourages early consultation with an orthopedic knee specialist to determine whether nonsurgical management is appropriate or whether surgical intervention is needed to prevent further deterioration.
Nonsurgical treatment options
Dr. Bennett recommends beginning with conservative therapies when appropriate.
The common nonsurgical options include physical therapy and knee injections. The injection options are:
- Biologic injections: These include platelet-rich plasma (PRP), bone marrow aspirate concentrate (BMAC) or stem cells.
- Viscosupplement injections.
- Corticosteroid injections.
While these injections can reduce symptoms and slow progression, they do not replace lost cartilage.
"Injecting the knee may decrease propagation of the defect, but it won't convert the damage to normal cartilage," Dr. Bennett explains. "With biologic injections, the knee may form scar type cartilage called fibrocartilage, but not normal articular cartilage."
Viscosupplement injections lubricate the area and can reduce symptoms for a period of time. Dr. Bennett describes the viscosupplement injections as "a type of knee oil job."
Corticosteroid injections can decrease pain and inflammation. However, corticosteroid injections may decrease the knee's ability to form scar cartilage. Dr. Bennett does not recommend cortical steroid injections for cartilage lesions.
Surgical options for cartilage restoration
When symptoms persist or defects are substantial, surgical intervention is the most effective path to restoring knee function, Dr. Bennett says. Mayo Clinic offers a full spectrum of cartilage restoration procedures.
Cartilage smoothing technique
A motorized arthroscopic shaver is used to debride the knee's surface and stimulate the formation of fibrocartilage. This option is often used for smaller defects.
Cartilage-forming techniques
Marrow stimulation. Small holes are created in the subchondral bone to allow marrow elements to enter the defect and promote fibrocartilage repair.
Osteochondral autograft transfer system (OATS). Cartilage plugs from nonweight-bearing regions of the patient's knee are transplanted into the defect. Dr. Bennett notes that OATS has a 92% chance of durability at 15 years.
Fresh osteochondral allografts. Donor cartilage is shaped into a cylinder and implanted after coring out the damaged area. This technique is useful for larger defects.
Matrix-associated autologous chondrocyte implantation (MACI). A small cartilage sample is harvested arthroscopically and expanded into a cartilage sheet in a laboratory. A template is cut to match the defect and implanted. MACI demonstrates approximately 90% durability at 15 years.
Granulated cartilage techniques. A mixture of the patient's cartilage and donor cartilage granules are placed into the defect to encourage new tissue formation.
Dr. Bennett emphasizes that defect size and geometry guide procedure selection.
"You can't always do an OATS if the defect is too big to take a piece from elsewhere in the knee."
Key factors in treatment selection
When determining a patient's optimal treatment pathway, Dr. Bennett evaluates:
- Age.
- Activity level.
- Weight.
- Leg alignment.
- Overall health.
Timeline for return to work or sport
Dr. Bennett integrates AI tools, current medical literature and his clinical experience to guide his recommendations about time frame for going back to one's career or athletics.
Dr. Bennett notes, however, that patient preferences in choosing treatments vary widely.
"Some patients say, 'You do what you think is right,' and some patients want to be involved in decision-making," he says.
Athletes often have multiple stakeholders involved in their care, says Dr. Bennett.
Why refer to Mayo Clinic
Dr. Bennett encourages clinicians to refer patients with articular cartilage injuries to Mayo Clinic, noting the medical center's comprehensive resources and efficient surgical scheduling.
"If patients are ready for surgery, they will get in quickly," he says.
Dr. Bennett says that his decision to join Mayo Clinic reflects his confidence in the system's capabilities.
"This system is literally the best in the world — you have access to everything," he adds.
For more information
Refer a patient to Mayo Clinic.