NASS Research: Is Allograft or Autograft the Superior Material?

Nothing beats Mother Nature.

Such was the consensus of a new study presented on Oct. 14 at the North American Spine Society’s 30th Annual Meeting in Chicago, Ill. Presented by Dageng Huang, M.D., a physician at Honghui Hospital in Xi’an, China, the analysis concluded that patients’ own bone material is superior to donor bone in posterior atlantoaxial fusion, a common neck surgery.

“Autograft is still the gold standard,” Huang said during his five-minute presentation at a morning study symposium. Huang’s evalulation, “Allograft versus Autograft for Posterior Atlantoaxial Fusion with Screw-Rod System: A Prospective Comparative Study,” was among 21 “Best Papers” selected by NASS from the record 1,180 scientific abstracts and session proposals submitted for this year’s meeting. The study was co-authored by Dingjun Hao, M.D.; Baorong He, M.D.; and Hua Guo, M.D.; (all with Honghui Hospital).

In spinal fusion surgery, two or more vertebrae are connected using screws, plates, rods and bone to stabilize the spine. Surgeons can use the patient’s own bone, which typically is harvested from the patient’s pelvic area in a relatively minor procedure, or donor bone (called allograft) from a tissue bank. Surgeons assess the fusion’s success using different tools, including computed tomography (CT) scans or by detecting movement on dynamic radiographs.

“In an effort to reduce a patient’s pain and complication risk, surgeons have been relying more on allograft bone for spine fusion,” said Michael D. Daubs, M.D., an orthopedic surgeon and NASS Annual Meeting program chairman. “But, as this study indicates, not all bone is created equal, and the way surgeons have been measuring fusion success needs to be carefully re-examined.”

In Huang’s prospective comparative study, 41 consecutive patients underwent posterior atlantoaxial fusion with a screw-rod system fixation. After learning about the possible advantages and disadvantages of each patients were given the unusual opportunity to choose between allograft bone or their own bone, harvested from the iliac crest of their own pelvis. Twenty-four chose allograft bone and 17 opted to harvest their own (autograft). The patients were tracked regularly, undergoing CT scans and dynamic radiographs every six months for at least 18 months.

At the final follow-up, only two patients (8.3 percent) in the allograft group achieved bony fusion based on CT imaging, while 15 patients (88 percent) reached the same goal, according to the study results. However, all 41 patients showed “no movement” on dynamic radiographs, which might lead some surgeons to conclude that the vertebrae fused successfully.

“This study indicates that not only is allograft unreliable for posterior atlantoaxial fusion, but we must be skeptical about using only dynamic radiographs to check fusion,” Daubs noted. “We should focus energy on making autograft fusion safer and less painful for our patients.”