A study published in Spine suggests that the stand-alone autograft technique, which is considered to be the gold standard for interbody fusion, has significantly worse clinical and radiological results compared with autograft supported by anterior plating or cage implant and anterior plating.
Petr Vanek, Department of Neurosurgery, Charles University, 1st Faculty of Medicine, Central Military Hospital, Prague, Czech Republic, and colleagues reported that there is very little evidence, regarding pain relief, to support one interbody fusion technique over another but they added that “Iliac autograft crest still seems to be the ‘gold standard’ for interbody fusion.” The authors wrote, because of the lack of evidence in this area, the optimum technique for interbody fusion “definitely needs to be studied in more detail” and commented: “The aim of this prospective study was to compare the three different methods of interbody fusion of the cervical spine that is, autograft in stand-alone technique, autograft with anterior plate, and PEEK (polyetheretherketone) cage filled by hydroxyapatite supported by anterior plate.”
In the prospective study, 81 patients with symptomatic cervical degenerative disc disease (involving one or two levels) with no response to conservative treatment after six weeks or more were assigned to one of three groups: one, stand-alone autograft insertion (28); two, autograft and anterior plate (18); and three, PEEK cage with beta-tricalcium phosphate and plate.
Immediately after the operation, the relative height of the operated segment compared with the preoperative state was 110% in group one and similar figures were reported in groups two and three (111% and 112%, respectively). After two years of follow-up, relative height of the stand-alone autograft in group one was below 95% of the initial height. However, Vanek et al reported: “Values of relative height in the other two groups remained above 105%, leading to a significant difference between these two groups and stand-alone autograft in all of the follow-up reviews since the sixth postoperative week (P<0.001 in all cases).” Additionally, after an initial slight increase in Cobb S angles in all three groups in the immediate postoperative period, the values in groups two and three decreased to preoperative values and remained stable during further follow-up while the values in group one decreased substantially and remained significantly lower than the values in the other two groups.
Furthermore, after surgery, patients in all the groups had significant improvements in the visual analogue scale (VAS), but the improvement was smaller in group one. Vanek et al added: “Satisfaction of patients with overall status and result of surgery was assessed after two years of follow-up on a dichotomic scale—satisfied versus unsatisfied. Significant difference was found among groups, with the highest proportion of unsatisfied patients in group one (p=0.034).”
According to Vanek et al, the loss of height, in comparison with the other two groups, in group one could be “explained only as a consequence of graft collapse”. However, they added that they could only speculate as to why there was such a significant loss of segment height in the first six weeks in the stand-alone group. They wrote: “It might be explained by the reduced firmness of the devitalised autograft in a slightly unstable situation in the segment without internal or external support.”
Vanek et al commented that smaller improvement in VAS scores and the higher proportion of unsatisfied patients in group one could not be explained by a low rate of fusion in this group as the rate of fusion was 100% in all three groups. They noted: “We could suppose that collapse of the graft with potential restenosis of the previously decompressed neural foramina and/or kyphotic deformity of the treated segment might be responsible for inferior clinical outcome in group one.”
They concluded their study by saying that their results “put in doubt the stand-alone fusion technique with autograft as a ‘gold standard.’”