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Atlantoaxial Arthrodesis with Autograft versus Allograft
Perspectives Commentary on: Is Allograft Sufficient for Posterior Atlantoaxial Instrumented Fusions with Screw and Rod Constructs? A Structured Review of Literature by Elliott et al. pp. 326-338.
Arnold H. Menezes, M.D. Professor and Vice Chairman, Department of Neurosurgery University of Iowa Hospitals and Clinics
Atlantoaxial Arthrodesis with Autograft versus Allograft Arnold H. Menezes
S
urgical techniques for posterior atlantoaxial fusion have evolved rapidly, with improved clinical outcomes. The goal is to stabilize the joint, decompress neural structures when necessary, recreate normal coronal and sagittal alignment before the arthrodesis procedure, and avoid adverse events (1). The fusion should act as a spacer and withstand loads of that particular joint. Because of dissimilar materials in the fusion construct between the recipient– host bone and the instrumentation, solid spine fusion is necessary with osseous integration using bone graft. The attainment of solid spine fusion is a race between graft reabsorption and adequate bone formation to withstand load and become a mature fusion mass, while the instrumentation provides the initial stability (5). Autografts provide a more osteogenic material, whereas allograft provides a slower osteoinductive material. The success of any bone graft or graft substitute may vary according to the particular environment (2). The motion and loading characteristics of various vertebral segments are ever-changing and vary further among anterior interbody and posterior laminar locations and other locations. Bone is a dynamic tissue that in normal circumstances is renewed through formation and balance resorption that is tightly coupled (4). Bone is remodeled to meet mechanical forces and demands that influence bone formation and resorption. This process is mediated by osteocytes, the putative mechanoreceptors that regulate other cells to choreograph mechanical load– induced bone remodeling. Osteoblasts deposit the bone matrix, and osteoclasts resorb bone. The long-term goal of bone grafting is graft incorporation. This incorporation should occur without subsidence or deformation (5). Autografts contain endogenous bone morphogenetic proteins (BMPs), which are osteoinductive. BMPs help to recruit osteoprogenitor cells and cause differentiation. Fresh frozen allografts contain some BMPs, whereas freeze-dried allografts
Key words 䡲 Arthrodesis 䡲 Atlantoaxial 䡲 Autograft 䡲 C1-2 䡲 C1-C2
Abbreviations and Acronyms BMP: Bone morphogenetic protein CT: Computed tomography
lack BMPs (11). The focus has been on use of recombinant BMP— bone expanders in conjunction with allografts. Bone from the iliac crest traditionally has been used to supplement spine fusion constructs. It has been termed the “gold standard” despite an extremely high complication rate at the donor site. Hillard et al. (6) reviewed 89 patients who underwent C1-2 transarticular fixation of all ages in a 5-year span. Iliac crest autografts were used in 42 patients with a complication rate of 16% at the donor site. The complications included pelvic fracture, retained foreign material, infection, hernias requiring repair, persistent pain, and hematomas. Despite complications, iliac autografts had a 95% fusion rate. In 47 patients, an allograft supplementation to the instrumentation was performed; this was a fitted allograft between C1 and C2 posterior arches maintaining high compression and anchorage. The fusion rate was 88%. Autografts healed faster. Kurz et al. (8) reviewed the complications and techniques of harvesting autogenous iliac bone grafts. They documented complications at the donor site including persistent pain, nerve and arterial injury, peritoneal perforation, sacroiliac joint instability, and herniation of abdominal contents through the defect in the ilium. These authors provided relevant anatomic considerations to help with avoiding these complications. The much-vaulted “gold standard” for donor bone leaves much to be desired. Other sites have been used with fewer complications and greater ease of obtaining the donor bone, such as calvaria and rib graft (1, 9, 10). I have used both sites consistently. In comparative series in 1998, the fusion rate with rib graft as opposed to iliac crest without instrumentation was 98.4%, whereas the fusion rate with iliac crest was 91% in a matched series of ⬎ 600 patients (10). Robertson and Menezes (9) also showed the use of calvarial bone grafts in individuals with high morbidity, such as class III rheumatoid arthritis, with a high success rate.
Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA To whom correspondence should be addressed: Arnold H. Menezes, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2012) 78, 3/4:239-240. DOI: 10.1016/j.wneu.2012.02.044
WORLD NEUROSURGERY 78 [3/4]: 239-240, SEPTEMBER/OCTOBER 2012
www.WORLDNEUROSURGERY.org
239
PERSPECTIVES
Winegar et al. (12) provided a systematic review of occipitocervical fusions in 2010. This was a review of 34 case studies that included 799 patients. Of patients who were instrumented, 97% had autografts. The fusion rate was 93% in all disease states. Most problems occurred with inflammatory states. Screw-rod fixation had the most success with bone fusion in ⬍ 4 months. However, the fusion rate was 93%. Jorgenson et al. (7) compared patients who underwent posterolateral lumbar fixation with one side using autograft and the other side using ethylene oxide–treated allograft. Radiographs were reviewed at 14 months and 27 months. These authors believed that the ethylene oxide–treated allografts were inferior to autograft. Several other studies claimed autograft to be superior to allograft (5, 7, 11). Anterior cervical grafting after disc removal or corpectomy undergoes axial load and cannot be compared with posterior cervical grafting. Similarly, anterior and posterior lumbar fixation has the same drawback in that the loads are different from the posterior cervical fusions. Fusion evaluations have been based on radiographs, dynamic stress views with flexion and extension of the cervical spine, and computed tomography (CT). Carreon et al. (3) reviewed the reliability of plain radiographs against fine-cut CT in the evaluation
REFERENCES 1. Ahmed R, Traynelis VC, Menezes AH: Fusions at the craniovertebral junction. Childs Nerv Syst 24:12091224, 2008. 2. Boden S: Point of view. A prospective analysis of autograft versus allograft in posterolateral lumbar fusion in the same patient. Spine 19:2053, 1994. 3. Carreon LY, Glassman SD, Djurasovic M: Reliability and agreement between fine-cut CT scans and plain radiography in the evaluation of posterolateral fusions. Spine J 7:39-43, 2007. 4. Chen JH, Liu C, You L, Simmons CA: Boning up on Wolff’s law: mechanical regulation of the cells that make and maintain bone. J Biomech 43:108-118, 2010. 5. Deutsch H, Haid R, Rodts G Jr, Mummaneni PV: The decision-making process: allograft versus autograft. Neurosurgery 60:S98-S102, 2007.
240
www.SCIENCEDIRECT.com
of posterolateral fusions. Findings of the CT scan agreed with findings of the radiographs in only half the patients. Assessment of the literature is difficult, especially with a varied population of surgeons with varying skills and diverse surgical techniques. Standardization is needed if one is to pool together the results. The difficulties with class III retrospective studies in the framework of literature review include inconsistent methods of surgery, decortication, joint packing (C1-2), fusion assessment, and the underlying problem of preconceived goals. A controlled, blinded study with a uniform method of evaluation is needed. Elliott et al. performed a structured review of the literature regarding allograft being sufficient for posterior atlantoaxial instrumented fusion with screw and rod construct. Autograft was used in 604 patients, and allograft was used in 88 patients. There were no differences in complications or mortality in the two groups and no difference in the fusion rates between the two groups. These study results are surprising. The topic under review has significant clinical implications in all varieties of patients. A controlled blinded uniform study performed prospectively is needed to benefit the patient and the spinal neurosurgeon.
6. Hillard VH, Fassett DR, Finn MA, Apfelbaum RI: Use of allograft bone for posterior C1-2 fusion. J Neurosurg Spine 11:396-401, 2009. 7. Jorgenson SS, Lowe TG, France J, Sabin J: A prospective analysis of autograft versus allograft in posterolateral lumbar fusion in the same patient. Spine 19:2048-2053, 1994.
11. Thalgott JS, Fogarty ME, Giuffre JM, Christenson SD, Epstein AK, Aprill C: A prospective, randomized, blinded, single-site study to evaluate the clinical and radiographic differences between frozen and freeze-dried allograft when used as part of a circumferential anterior lumbar interbody fusion procedure. Spine 34:1251-1256, 2009.
8. Kurz LT, Garfin SR, Booth RE: Harvesting autogenous iliac bone grafts: a review of complications and techniques. Spine 14:1324-1331, 1989.
12. Winegar CD, Lawrence JP, Friel BC, Fernandez C, Hong J, Maltenfort M, Anderson PA, Vaccaro AR: A systematic review of occipital cervical fusion: techniques and outcomes. J Neurosurg Spine 13:5-16, 2010.
9. Robertson SC, Menezes AH: Occipital calvarial bone graft in posterior occipitocervical fusion. Spine 23:249-255, 1998.
Citation: World Neurosurg. (2012) 78, 3/4:239-240. DOI: 10.1016/j.wneu.2012.02.044 Journal homepage: www.WORLDNEUROSURGERY.org
10. Sawin PD, Traynelis VC, Menezes AH: A comparative analysis of fusion rates and donor-site morbidity for autogenic rib and iliac crest bone grafts in posterior cervical fusions. J Neurosurg 88:255-265, 1998.
Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2012 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2012.02.044
Arnold H. Menezes, M.D. Professor and Vice Chairman, Department of Neurosurgery University of Iowa Hospitals and Clinics
Atlantoaxial Arthrodesis with Autograft versus Allograft Arnold H. Menezes
S
urgical techniques for posterior atlantoaxial fusion have evolved rapidly, with improved clinical outcomes. The goal is to stabilize the joint, decompress neural structures when necessary, recreate normal coronal and sagittal alignment before the arthrodesis procedure, and avoid adverse events (1). The fusion should act as a spacer and withstand loads of that particular joint. Because of dissimilar materials in the fusion construct between the recipient– host bone and the instrumentation, solid spine fusion is necessary with osseous integration using bone graft. The attainment of solid spine fusion is a race between graft reabsorption and adequate bone formation to withstand load and become a mature fusion mass, while the instrumentation provides the initial stability (5). Autografts provide a more osteogenic material, whereas allograft provides a slower osteoinductive material. The success of any bone graft or graft substitute may vary according to the particular environment (2). The motion and loading characteristics of various vertebral segments are ever-changing and vary further among anterior interbody and posterior laminar locations and other locations. Bone is a dynamic tissue that in normal circumstances is renewed through formation and balance resorption that is tightly coupled (4). Bone is remodeled to meet mechanical forces and demands that influence bone formation and resorption. This process is mediated by osteocytes, the putative mechanoreceptors that regulate other cells to choreograph mechanical load– induced bone remodeling. Osteoblasts deposit the bone matrix, and osteoclasts resorb bone. The long-term goal of bone grafting is graft incorporation. This incorporation should occur without subsidence or deformation (5). Autografts contain endogenous bone morphogenetic proteins (BMPs), which are osteoinductive. BMPs help to recruit osteoprogenitor cells and cause differentiation. Fresh frozen allografts contain some BMPs, whereas freeze-dried allografts
Key words 䡲 Arthrodesis 䡲 Atlantoaxial 䡲 Autograft 䡲 C1-2 䡲 C1-C2
Abbreviations and Acronyms BMP: Bone morphogenetic protein CT: Computed tomography
lack BMPs (11). The focus has been on use of recombinant BMP— bone expanders in conjunction with allografts. Bone from the iliac crest traditionally has been used to supplement spine fusion constructs. It has been termed the “gold standard” despite an extremely high complication rate at the donor site. Hillard et al. (6) reviewed 89 patients who underwent C1-2 transarticular fixation of all ages in a 5-year span. Iliac crest autografts were used in 42 patients with a complication rate of 16% at the donor site. The complications included pelvic fracture, retained foreign material, infection, hernias requiring repair, persistent pain, and hematomas. Despite complications, iliac autografts had a 95% fusion rate. In 47 patients, an allograft supplementation to the instrumentation was performed; this was a fitted allograft between C1 and C2 posterior arches maintaining high compression and anchorage. The fusion rate was 88%. Autografts healed faster. Kurz et al. (8) reviewed the complications and techniques of harvesting autogenous iliac bone grafts. They documented complications at the donor site including persistent pain, nerve and arterial injury, peritoneal perforation, sacroiliac joint instability, and herniation of abdominal contents through the defect in the ilium. These authors provided relevant anatomic considerations to help with avoiding these complications. The much-vaulted “gold standard” for donor bone leaves much to be desired. Other sites have been used with fewer complications and greater ease of obtaining the donor bone, such as calvaria and rib graft (1, 9, 10). I have used both sites consistently. In comparative series in 1998, the fusion rate with rib graft as opposed to iliac crest without instrumentation was 98.4%, whereas the fusion rate with iliac crest was 91% in a matched series of ⬎ 600 patients (10). Robertson and Menezes (9) also showed the use of calvarial bone grafts in individuals with high morbidity, such as class III rheumatoid arthritis, with a high success rate.
Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA To whom correspondence should be addressed: Arnold H. Menezes, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2012) 78, 3/4:239-240. DOI: 10.1016/j.wneu.2012.02.044
WORLD NEUROSURGERY 78 [3/4]: 239-240, SEPTEMBER/OCTOBER 2012
www.WORLDNEUROSURGERY.org
239
PERSPECTIVES
Winegar et al. (12) provided a systematic review of occipitocervical fusions in 2010. This was a review of 34 case studies that included 799 patients. Of patients who were instrumented, 97% had autografts. The fusion rate was 93% in all disease states. Most problems occurred with inflammatory states. Screw-rod fixation had the most success with bone fusion in ⬍ 4 months. However, the fusion rate was 93%. Jorgenson et al. (7) compared patients who underwent posterolateral lumbar fixation with one side using autograft and the other side using ethylene oxide–treated allograft. Radiographs were reviewed at 14 months and 27 months. These authors believed that the ethylene oxide–treated allografts were inferior to autograft. Several other studies claimed autograft to be superior to allograft (5, 7, 11). Anterior cervical grafting after disc removal or corpectomy undergoes axial load and cannot be compared with posterior cervical grafting. Similarly, anterior and posterior lumbar fixation has the same drawback in that the loads are different from the posterior cervical fusions. Fusion evaluations have been based on radiographs, dynamic stress views with flexion and extension of the cervical spine, and computed tomography (CT). Carreon et al. (3) reviewed the reliability of plain radiographs against fine-cut CT in the evaluation
REFERENCES 1. Ahmed R, Traynelis VC, Menezes AH: Fusions at the craniovertebral junction. Childs Nerv Syst 24:12091224, 2008. 2. Boden S: Point of view. A prospective analysis of autograft versus allograft in posterolateral lumbar fusion in the same patient. Spine 19:2053, 1994. 3. Carreon LY, Glassman SD, Djurasovic M: Reliability and agreement between fine-cut CT scans and plain radiography in the evaluation of posterolateral fusions. Spine J 7:39-43, 2007. 4. Chen JH, Liu C, You L, Simmons CA: Boning up on Wolff’s law: mechanical regulation of the cells that make and maintain bone. J Biomech 43:108-118, 2010. 5. Deutsch H, Haid R, Rodts G Jr, Mummaneni PV: The decision-making process: allograft versus autograft. Neurosurgery 60:S98-S102, 2007.
240
www.SCIENCEDIRECT.com
of posterolateral fusions. Findings of the CT scan agreed with findings of the radiographs in only half the patients. Assessment of the literature is difficult, especially with a varied population of surgeons with varying skills and diverse surgical techniques. Standardization is needed if one is to pool together the results. The difficulties with class III retrospective studies in the framework of literature review include inconsistent methods of surgery, decortication, joint packing (C1-2), fusion assessment, and the underlying problem of preconceived goals. A controlled, blinded study with a uniform method of evaluation is needed. Elliott et al. performed a structured review of the literature regarding allograft being sufficient for posterior atlantoaxial instrumented fusion with screw and rod construct. Autograft was used in 604 patients, and allograft was used in 88 patients. There were no differences in complications or mortality in the two groups and no difference in the fusion rates between the two groups. These study results are surprising. The topic under review has significant clinical implications in all varieties of patients. A controlled blinded uniform study performed prospectively is needed to benefit the patient and the spinal neurosurgeon.
6. Hillard VH, Fassett DR, Finn MA, Apfelbaum RI: Use of allograft bone for posterior C1-2 fusion. J Neurosurg Spine 11:396-401, 2009. 7. Jorgenson SS, Lowe TG, France J, Sabin J: A prospective analysis of autograft versus allograft in posterolateral lumbar fusion in the same patient. Spine 19:2048-2053, 1994.
11. Thalgott JS, Fogarty ME, Giuffre JM, Christenson SD, Epstein AK, Aprill C: A prospective, randomized, blinded, single-site study to evaluate the clinical and radiographic differences between frozen and freeze-dried allograft when used as part of a circumferential anterior lumbar interbody fusion procedure. Spine 34:1251-1256, 2009.
8. Kurz LT, Garfin SR, Booth RE: Harvesting autogenous iliac bone grafts: a review of complications and techniques. Spine 14:1324-1331, 1989.
12. Winegar CD, Lawrence JP, Friel BC, Fernandez C, Hong J, Maltenfort M, Anderson PA, Vaccaro AR: A systematic review of occipital cervical fusion: techniques and outcomes. J Neurosurg Spine 13:5-16, 2010.
9. Robertson SC, Menezes AH: Occipital calvarial bone graft in posterior occipitocervical fusion. Spine 23:249-255, 1998.
Citation: World Neurosurg. (2012) 78, 3/4:239-240. DOI: 10.1016/j.wneu.2012.02.044 Journal homepage: www.WORLDNEUROSURGERY.org
10. Sawin PD, Traynelis VC, Menezes AH: A comparative analysis of fusion rates and donor-site morbidity for autogenic rib and iliac crest bone grafts in posterior cervical fusions. J Neurosurg 88:255-265, 1998.
Available online: www.sciencedirect.com 1878-8750/$ - see front matter © 2012 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY, DOI:10.1016/j.wneu.2012.02.044