Knowledge of function, vascularity needed for effective labral repair

SAN FRANCISCO — To properly handle cases involving the labrum, it is important for surgeons to understand its function and how — or even if — it should be repaired, according to a presentation here.

“There are a lot of functions of the labrum,” Marc R. Safran, MD, said during a featured lecture on the labrum at the 2011 Annual Meeting of the Arthroscopy Association of North America. “It contributes both to the total articulating surface, as well as the volume and depth of the joint itself. It also serves as a stabilizing force, stabilizing function as you take the hip through the range of motion.”

The labrum also assists in keeping the fluid of the articular cartilage in place assisting in distributing force within the joint as a barrier, as well as keeping fluid within the articular cartilage. Performing a labrectomy, Safran said, allows for a quicker loss of fluid from that joint, and thus, allows deformation of the articular cartilage and increased forces to the cartilage.

Furthermore, he noted, the labrum helps maintain diffusion pressure within the joint — which allows the synovial fluid in the joint to supply nutrition to the articular cartilage.

“Having a labrum helps limit cartilage deformation and stress, and helps contribute to joint transmission,” he added. “Having the labrum helps with articular cartilage nutrition. The labrum functions like a seal.”

Vascularity

The labrum also has four different types of nerve endings and corpuscles, Safran reported, meaning it serves both as a pain sensor and as appropriate reception for the hip joint itself. Most of the blood supply comes into the labrum through the capsular side, but the labrum is largely avascular — which means an intrasubstance tear is unlikely to heal if simply sewn together.

“When we see these intrasubstance tears, we do not try to repair them at this point in time,” Safran said. “We do partial labrectomy. Whereas if you have injury at the labral-chondral junction, you can go ahead and sew this back down to the acetabulum and rely on the blood supply from the bone itself to heal the labrum back down to the acetabular rim.”

However, the potential issue with partial labrectomy is the scattered data to support its use. Safran pointed out a 68% to 92% positive result rate throughout the literature, but cautioned many of these cases are not isolated labral tears.

“Ones associated with articular cartilage lesions have a poorer outcome, so we know that with combined lesions, results can drop significantly,” he said.

Impingement issues

In discussing the literature’s scattered findings for partial labrectomy, Safran noted that some study findings were recorded before physicians’ understanding of femoroacetabular impingement (FAI).

“The outcomes are better if you treat the FAI along with the labral tear, so some of the problems with the published outcomes of partial labrectomy is they did not know about FAI,” he said. “It was not addressed, so the outcomes were poor.”

The key to repairing the labrum, Safran reported, is preparing the bony bed. In doing this, the anchor should be placed at the rim, the suture should be placed and the underlying cause should be addressed.

“If there is impingement, you want to address the impingement,” he said.

“You can go around the labrum and do a simple repair, but I think that pulls the labrum away from the femoral head itself,” he added. “What we try to do is a vertical mattress-type of suture, which allows the edge of the labrum to still function as a seal on the femoral head.”

Postoperative weight bearing and motion should be limited, Safran noted, and the basis for any limits to motion are directly associated with the location of the labral repair.

Need for research

Safran noted that more evidence-based research is needed on labral repair.

“We do not really know the consequence of a labrectomy, clinically,” he said. “We do not know the consequence of leaving a torn labrum, in fact.”

He added that, when necessary, partial removal of the labrum should always be performed conservatively.

“Recent studies showed when you do a labral repair, the strains on the articular cartilage in the femoral head are less as compared to the torn labrum and resected labrum,” Safran said. However, he added that there are no published, clinical studies on isolated labral repair. “When you look for whatever guidance you can, labral repair does seem to be better both in the open and arthroscopic literature for FAI, and the outcomes seem to be better when you do a labral repair in conjunction with FAI surgery as compared to debridement.” – by Robert Press

Reference:

• Safran M. The state of the labrum: To repair or debride. Feature lecture #4. Presented at the 2011 Annual Meeting of the Arthroscopy Association of North America. April 14-16. San Francisco.

• Marc R. Safran, MD, can be reached at 450 Broadway St., Redwood City, CA 94063; 650-723-5643; email: msafran@stanford.edu.
• Disclosure: Safran receives royalties from Stryker; is a paid consultant for Cool Systems Inc. and Arthrocare; and is an unpaid consultant for Cradle Medical Inc. and Biomimedica. He receives research support from Ferring Pharmaceuticals and Smith & Nephew and royalties from Wolters Kluwer Health – Lippincott Williams & Wilkins and Saunders/Mosby-Elsevier. He is also on the editorial/governing board for the American Journal of Sports Medicine and a board/committee member of the International Society of Hip Arthroscopy, American Shoulder and Elbow Surgeons, American Orthopaedic Society for Sports Medicine, International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine, and the Society for Tennis Medicine and Science.