The grades of recommendations (standards, guidelines, and options) and classes of evidence (I–III) are defined at the end of the "Major Recommendations" field.
Standards. The use of autologous bone or recombinant human bone morphogenetic protein (rhBMP-2) bone graft substitute is recommended in the setting of an anterior lumbar interbody fusion (ALIF) in conjunction with a threaded titanium cage.
Guidelines. There is insufficient evidence to recommend a treatment guideline.
Options 1) Recombinant human BMP-2 in combination with hydroxyapatite (HA) and tricalcium phosphate may be used as a substitute for autograft bone in some cases of posterolateral fusion (PLF). 2) Several formulations of calcium phosphate exist and are recommended as bone graft extenders, especially when used in combination with autologous bone.
Summary
Despite the large volume of animal data regarding the use of synthetic bone graft substitutes or extenders, there are very few data regarding the use of these substances for fusion in lumbar degenerative disease. The best available data indicate that rhBMP-2 is a viable alternative to autograft bone for interbody fusion procedures. This same substance may also be a viable alternative to autograft for posterolateral fusion; however, definitive medical evidence is not yet available. There is little, if any, medical evidence to support the use of other biological agents at the present time. As promising new compounds are brought to market, well-designed cohort studies and randomized trials will be required to determine the actual usefulness of these compounds in clinical practice. It is important not to generalize the results obtained with one preparation or application to different preparations or applications.
The use of synthetic calcium phosphate ceramics as graft extenders appears to be reasonable in certain situations. The medical evidence available regarding their use is limited and of poor quality. Further study will be required to establish their utility for use in spinal fusion.
Definitions:
Grades of Recommendation
Standards Recommendations of the strongest type, based on Class I evidence reflecting a high degree of clinical certainty
Guidelines Recommendations based on Class II evidence reflecting a moderate degree of clinical certainty
Options Recommendations based on Class III evidence reflecting unclear clinical certainty
Classes of Evidence
Class I Evidence from one or more well-designed, randomized controlled clinical trials, including overviews of such trials
Class II Evidence from one or more well-designed comparative clinical studies, such as nonrandomized cohort studies, case-control studies, and other comparable studies, including less well-designed randomized controlled trials
Class III Evidence from case series, comparative studies with historical controls, case reports, and expert opinion as well as significantly flawed randomized controlled trials