Today's News

Wednesday, March 15, 2000

Allograft bone button for rotator cuff repair affords strength

The use of an allograft bone button for rotator cuff repairs appears to afford excellent pull out strength and reproducible locking in cancellous bone and is viable for repair of the rotator cuff tendon.

Peter M. Bonutti, MD, orthopaedic surgeon, Bonutti Orthopedic Clinic, Effingham, Ill., who presented a study at scientific exhibit 10, observed that rotator cuff repair is increasingly being performed with metallic anchoring/fixation systems. "These systems have variable degrees of mechanical integrity and are associated with complications if there is pull out or bone remodeling," Dr. Bonutti said. "Biodegradable anchoring systems also are available, however, there is concern of osteolysis and wear from the degradation products."

Because of these concerns, allograft bone was investigated as an alternative material for tissue fixation to bone. Allograft buttons were cut from cortical bone into 3 mm-diameter, 6 mm-long cylinders. Two transverse holes were drilled in the button in order to allow suture to be passed through the allograft. The bone button was used to repair 50 consecutive rotator cuff tears, ranging from small to massive and was followed by serial radiographs and clinical exams. The bone button was inserted through a 3.4 mm diameter hole to a depth of 20 mm where it was toggled and locked in the bone.

Surgical results showed that the bone button was very effective in locking in cancellous bone and did not require cortical fixation, Dr. Bonutti said. Sequential radiographs showed the bone button clearly locked in the cancellous bone and did not rely on a cortical rim for fixation. The allograft buttons incorporated into the host bone and no failures were identified. Results of mechanical testing showed that the pull out strength of the cortical bone buttons averaged 36 pounds with a standard deviation of two pounds. No button migration was noted under cyclical load testing.

The researchers are Frank S. Lee, MD, and Timothy J. Gray, MD, both orthopaedic surgeons with Bonutti Orthopedic Clinic, Effingham, Ill.; and Matthew J. Cremens, BS, research engineer, Bonutti Research, Inc.

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Last modified 22/February/2000 by IS