Underwater Reaming Technique Boosts Success of Osteochondral Allograft Transplants

Osteochondral allograft (OCA) plug harvesting performed while submerged in saline significantly improves the viability of cartilage cells, potentially leading to better long-term outcomes for patients undergoing knee cartilage repair, according to a recent study co-authored by Houston Methodist orthopedic surgeon Dr. Sachin Allahabadi.

Published in The American Journal of Sports Medicine, the research shows that underwater reaming preserves 10 to 13 percent more viable chondrocytes compared with the traditional handheld irrigation technique. This advancement addresses a key challenge in cartilage transplantation: maintaining cell health during the graft harvest process.

"Cartilage is extremely sensitive to heat," said Dr. Allahabadi. "Traditional reaming generates thermal energy that can damage chondrocytes, which are essential for graft integration. By performing the entire process submerged in saline, we can reduce that thermal injury and give the graft a better chance of thriving."

OCA transplantation can be described as filling a pothole on an otherwise good road, rather than repaving the entire surface. The technique replaces a localized cartilage defect with a donor graft containing both cartilage and bone, making it an ideal solution for younger patients with minimal arthritis who have sustained focal knee injuries.

"These patients are often too young for total knee replacement, which would be overkill for just this one divot," Dr. Allahabadi explained. "By addressing the defect early, we can delay arthritis progression and preserve the natural knee for as long as possible."

During a typical OCA procedure, surgeons use a coring reamer to create a cylinder-shaped cavity at the defect site, matching it with a plug of cartilage and bone from a donor. However, the drilling process creates heat that can kill cells, reducing the graft's ability to integrate with the patient's own tissue.

"Our study found that when the graft was harvested under water, cartilage cell viability was significantly better," Dr. Allahabadi said. "It's a simple technique that doesn't add time or require new equipment, but it could have a big impact on outcomes."

Dr. Allahabadi began exploring OCA viability during his orthopedic fellowship at Rush University in Chicago, under the mentorship of senior author Dr. Adam Yanke. He continued working with the team on the research after he joined Houston Methodist.

Current data suggests that osteochondral allograft procedures are about 80 to 85 percent successful at five to 10 years. By maximizing chondrocyte viability, the researchers believe they can improve these odds.

Additionally, healthier grafts typically mean more pain relief, reduced swelling and improved mobility for the patient as the transplanted bone and cartilage integrate seamlessly into the knee joint.

"Our goal is always to give the patient the best starting point," Dr. Allahabadi said. "If we preserve more cartilage cells, the graft is more likely to succeed."

The team is now exploring methods to minimize thermal injury on the recipient side of the procedure, where submerged cooling is not feasible.

"This is just the beginning," Dr. Allahabadi noted. "As techniques evolve, we'll continue to look for ways to optimize every step of these procedures. I am excited to continue similar research through the great support that Houston Methodist offers for physician-scientists."