- Email: [email protected]
Patient satisfaction and radiographic outcomes after lumbar spinal fusion without iliac crest bone graft or transverse process fusion
Journal of Clinical Neuroscience 16 (2009) 1184–1187
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Clinical Study
Patient satisfaction and radiographic outcomes after lumbar spinal fusion without iliac crest bone graft or transverse process fusion Frank L. Acosta a,*, Jordan M. Cloyd a, Henry E. Aryan b, Christopher P. Ames a a b
Department of Neurological Surgery, University of California, San Francisco, 505 Parnassus Avenue, M779, Box 0112, San Francisco 94143, CA, USA Division of Neurological Surgery, University of California, San Diego, CA, USA
a r t i c l e
i n f o
Article history: Received 24 October 2008 Accepted 7 December 2008
Keywords: Lumbar spinal fusion Iliac crest Bone morphogenic protein Allograft Subjective outcomes Back pain
a b s t r a c t Iliac crest bone graft (ICBG) remains the gold standard for promoting bony fusion of the spine. However, harvest-site infection and pain are two of the most significant drawbacks of using iliac crest autograft in spinal fusion procedures. The rationale for its continued use, despite these drawbacks, has been based on the relatively higher rate of fusion reported in the literature. Therefore, the objective of this study was to determine whether modern allograft and fusion-promoting materials combined with local bone graft results in acceptable fusion rates and patient satisfaction. We retrospectively reviewed the clinical, surgical, and radiographic records of 200 consecutive patients with symptomatic degenerative diseases of the lumbar spine who underwent non-revision fusion using local bone graft combined with recombinant human bone morphogenetic protein (rhBMP)-2 with or without allograft. Rates of radiographic fusion and patient satisfaction were analyzed at discharge, 6 months, and 12 months, and every year thereafter. Mean follow-up was 32 months. Fusion was performed across an average of 2.5 levels and the overall fusion rate was 97%. In patients undergoing posterior fixation only there was a 5% incidence of pseudarthrosis, while the incidence was only 0.5% for patients undergoing circumferential fixation. Overall patient satisfaction at discharge was good to excellent in over 90% of patients and did not significantly change at the 6 month, 12 month and 24 month follow-up. In conclusion, there is no significant difference in rates of spinal fusion using laminectomy bone autograft combined with rhBMP-2 with or without allograft, compared to historical controls using ICBG. Fusion rates may be further improved with the use of circumferential fixation. Patient satisfaction remained high and might be because the morbidity associated with harvesting ICBG was avoided, as was the additional muscle dissection required for the fusion of lateral transverse processes. Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction Autologous iliac crest bone graft (ICBG) remains the gold standard for promoting bony fusion in lumbar spine arthrodesis despite a limited supply and potential complications associated with harvesting the bone graft. These complications include infection, hematoma, neurovascular damage, pelvic instability and fracture as well as severe and persistent donor site pain.1,2 The incidence of morbidity associated with harvesting the ICBG ranges between 6% and 40%.2–8 To avoid the complications and disability associated with obtaining the iliac crest bone, allograft bone has also been used to promote fusion. Although allografts carry potential risks of infection, immunologic reaction, and infectious disease transmission, a recent randomized controlled trial demonstrated favorable clinical outcomes obviously without the donor site pain compared to patients fused with ICBG.9 * Corresponding author. Tel.: +1 415 353 3998; fax: +1 415 502 1320. E-mail address: [email protected] (F.L. Acosta). 0967-5868/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.jocn.2008.12.006
The rationale for the continued used of ICBG is that some investigators have claimed that allograft results in inferior fusion rates compared to iliac crest autograft.10–13 However, other clinical reports have shown similar fusion rates with use of allograft compared to ICBG14,15 and a recent animal study showed greater rates of successful fusion with demineralized bone matrix compared to autograft.16 In addition to allograft bone, some investigators have used bone morphogenetic proteins (BMPs) to promote fusion in anterior lumbar interbody fusion (ALIF)8,17 and posterolateral fusion with and without instrumentation.18–20 Modern spine fusion techniques, including allograft and osteogenic materials combined with local bone graft, may result in comparable rates of fusion and, by alleviating the need for harvesting ICBG, improved patient satisfaction. The purpose of this study is to determine whether local bone graft, combined with modern fusion-promoting agents and allograft, can result in comparable rates of radiographic lumbar spinal fusion as ICBG. We present 200 consecutive patients with symptomatic degenerative lumbar spine disease who underwent
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non-revision instrumented fusion using local bone graft and recombinant human bone morphogenetic protein (rhBMP)-2 with or without allograft. Specifically, all patients were fused without ICBG and/or transverse process fusion. We hypothesize similar rates of fusion will be achieved and patient satisfaction will be greater due to reducing morbidity associated with harvesting ICBG compared to historical controls. 2. Materials and methods A retrospective review of the clinical, surgical and radiographic records of 200 consecutive patients presenting with symptomatic degenerative disease of the lumbar spine was performed (Table 1). Diagnoses were degenerative disc disease (DDD) with stenosis (106 patients), degenerative spondylolisthesis (52), spondylolysis (25) and adult degenerative scoliosis (17). The mean age was 59 (range 42–71) and there were 88 males (44%). Patients with a history of previous fusion surgery and persons judged medically unfit to undergo the surgical operation by an anesthesiologist were excluded from the study. Non-operative management of pain, including medication and epidural steroid injection, was exhausted in all patients. All surgeries were performed by the senior author (CPA). All patients underwent laminectomy followed by posterior spinal fusion (PSF). Posterior facet fusion was achieved by packing morselized laminectomy autograft through the decorticated facet joints. Local bone was harvested with a combination of Leksell and Kerrison rongeurs. All soft tissue was removed and the remaining bone ground into small morsels with a Leksell rongeur. GraftonÒ allograft (Osteotech; Eatontown, NJ, USA) was used only when minimal laminectomy bone could be acquired. Posterior spinal instrumentation (PSI) with pedicle screw-rod fixation was then performed. No patients underwent transverse process on-lay fusion. Ninety percent of patients also underwent anterior (ALIF) or tranforaminal lumbar interbody fusion (TLIF) using rhBMP-2 packed into a carbon fiber interbody graft (CougarTM System) (Depuy Spine; Raynham, MA, USA) or femoral ring allograft. All defor-
mity cases were treated with ALIF using rhBMP-2 packed into a titanium Pyramesh cage (Medtronic; Memphis, TN, USA). Radiographic evidence of fusion and patient satisfaction were analyzed at discharge, 6 months, and 12 months and then every year thereafter. Solid bony fusion was defined as lack of motion, hardware migration, fracture, or lucency on flexion–extension radiographs. Patients were asked two questions to document their level of satisfaction with the surgery: (i) what is your overall level of satisfaction with the surgery? (answer choices: poor, below average, average, good, excellent); and (ii) would you still make the same decision to have the procedure? (answer choices: yes, no). 3. Results The operative results are displayed in Table 2. A total of 130 patients underwent ALIF with PSF/PSI and were fused across a mean of 3.2 levels with a 100% fusion rate. Fifty patients were fused across 2.5 levels with TLIF and PSF/PSI with a fusion rate of 92%, while 20 patients underwent only PSF/PSI across an average of 2.3 levels and had a 90% fusion rate. There were no significant differences in fusion rates between the three procedural groups (p > 0.05). Overall fusion rate was 97% with an average of 32 months (range 6–40 months) follow-up. Four patients in the TLIF group had a pseudarthrosis: one patient had diabetes and 2 were smokers. Two patients in the PSF/PSI only group had pseudarthrosis and both were smokers. All patients in whom fusion did not occur underwent revision fusion with ALIF and posterior fixation. There were 11 perioperative complications (Table 3): 5 wound infections (2 PSF/PSI, 2 ALIF, 1 TLIF), 2 cerebrospinal fluid (CSF) leaks (1 PSF/PSI, 1 TLIF), 3 deep vein thromboses (2 ALIF, 1 TLIF), and 1 case of pneumonia (1 ALIF). Overall patient satisfaction at discharge was good to excellent in over 90% of patients (ALIF, 93%; TLIF, 94%; PSF/PSI, 91%) and did not significantly change at 6 month, 12 month or 24 month follow-up (Fig. 1A). There was no statistically significant difference in results when controlling for procedure or diagnosis. Over 90% of patients responded that they would make the same decision regarding their surgical care again and there were no significant differences among diagnoses or procedures (Fig. 1B).
Table 1 Characteristics of patients presenting with symptomatic degenerative disease of the lumbar spine Total no. of patients
200
Mean age (range) Sex Male (%) Female (%) Diagnosis DDD (%) Degenerative spondylolisthesis Spondylolysis (%) Scoliosis (%) Mean follow-up, months (range)
59 (42–71) 88 (44) 112 (56) 106 (53) 52 (26) 25 (13) 17 (9) 32 (6–40)
DDD = degenerative disc disease.
Table 3 Operative complications by surgical procedure Type of surgery
Infection
CSF leak
DVT
Pneumonia
Pseudarthrosis
Total (%)
ALIF + PSF/PSI TLIF + PSF/PSI PSF/PSI Total
2 1 2 5
0 1 1 2
2 1 0 3
1 0 0 1
0 4 2 6
5 (3.8%) 3 (6%) 5 (25%)
ALIF = anterior lumbar interbody fusion, CSF = cerebrospinal fluid, DDD = degenerative disc disease, DVT = deep vein thrombosis, PSF = posterior spine fusion, PSI = pedicle screw instrumentation, TLIF = transforaminal lumbar interbody fusion.
Table 2 Operative results based on surgical procedure Type of surgery
ALIF + PSF/PSI TLIF + PSF/PSI PSF/PSI
No. patients (%)
130 (65) 50 (25) 20 (10)
Diagnosis (%) DDD
Spondylolisthesis
Spondylosis
Scoliosis
81 (62) 18 (36) 7 (35)
25 (19) 24 (48) 3 (15)
7 (5) 8 (16) 10 (50)
17 (13) 0 0
Mean levels fused
Fusion rate
3.2 2.5 2.3
100 92 90
ALIF = anterior lumbar interbody fusion, DDD = degenerative disc disease, TLIF = transforaminal lumbar interbody fusion, PSF = posterior spine fusion, PSI = pedicle screw instrumentation.
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Fig. 1. Clinical outcomes. (A) Percentage of patients reporting a good to excellent outcome at discharge, and at 6 month, 12 month and 24 month follow-up. (B) Percentage of patients responding ‘‘yes” to the question: would you make the same decision to have the procedure again? ALIF = anterior lumbar interbody fusion; D/C = discharge, DDD = degenerative disc disease, PSF = posterior spine fusion; PSI = pedicle screw instrumentation, TLIF = transforaminal lumbar interbody fusion.
4. Discussion Since the first description of using autologous bone graft from the iliac crest to promote bony fusion in 194621, it has been recognized that there are significant complications associated with harvesting the graft. These complications include infection, hematoma, neurovascular damage, pelvic instability and fracture, abdominal herniation and peritoneal perforation.2,6,22,23 Perhaps more importantly is the persistent pain and discomfort that is caused by obtaining the autograft. Several studies have shown long-term donor site pain in 15% to 39% of patients 2 years postoperatively.3,5,6,24–27 Interestingly, patients who have an ICBG harvested for a lumbar spine fusion tend to have greater postoperative donor site pain than those needing autograft for other reasons.3 A recent prospective study by Sasso et al. revealed 31% of patients reported some level of donor site pain at 2 year follow-up while 16% reported fair or poor appearance of the graft site.7 The rationale for the continued use of ICBG despite its known morbidities is the belief that using iliac crest autograft results in a higher rate of fusion. In a recent review of the spine fusion literature since the mid-1980s, Bono and Lee report the mean fusion rate using autogenous bone was 87% while allograft fusion alone and a mixture of autograft and allograft both resulted in fusion rates of 86%.28 They conclude that allograft results in a similar rate of fusion, although their analysis includes only a few allograft patients (n = 206) compared to autograft patients (n = 4934). Butterman et al. reported on a series of 38 patients undergoing revision anterior–posterior fusions with a 100% fusion rate in those fused with autograft and 94% fused with allograft.12 Nasca and Whelchel found no significant differences in fusion rates (86.6% versus 87.0%) between autograft and allograft in their study of
152 patients.29 Wimmer et al. studied 94 consecutive patients undergoing circumferential fusion for spondylolisthesis and found a 97% rate of fusion in patients with ICBG and 92% in patients using femoral ring allograft.14 Most recently, Dimar et al. searched for evidence of pseudarthrosis using fine-cut CT scans in ICBG versus rhBMP-2 with compression-resistant matrix and found a significantly greater fusion rate in the BMP/compression-resistant matrix group compared to autograft (88% versus 73%).24 In the current study, our fusion rate of 97% overall compares favorably to the available data for fusions using ICBG and therefore provides a reasonable alternative to the current gold standard approach. Along with a successful fusion, patient satisfaction remains one of the most important outcomes for any surgery. In their review, Bono and Lee found good–excellent clinical outcomes in 76% to 78% of fusions using autologous bone only.28 Gibson et al. compared clinical outcomes in fusions with allograft versus iliac crest autograft and found that patients in the ICBG group had greater pain scores 1 year postoperatively and they attributed this to donor site pain.9 Vaccaro et al. reported a clinical success, defined as a 20% improvement in preoperative Oswestry Disability Index (ODI) scores, in 85% of patients fused with rhBMP-7 compared to only 64% in those with iliac crest bone at 2-year follow-up.19 In our study, the overwhelming majority of patients reported a good–excellent outcome, regardless of procedure or diagnosis. Furthermore, over 90% of patients responded that they would make the same decision regarding their surgical care at all times and for all procedures. One reason patient satisfaction may have been so high in our study is that the pain and discomfort associated with harvesting the ICBG, as well as the additional muscle dissection required for fusion of the transverse processes, were avoided. The results of our study pose a few interesting findings. First, ALIF was found to be superior to TLIF in terms of fusion rate, although these differences were not statistically significant. It is possible that the anterior approach allows greater fusion surface preparation and provides greater stability due to the larger cages used. One biomechanical comparison of the two approaches found that ALIF provided greater segmental stability in flexion–extension and axial rotation compared to TLIF, although these differences were minor after pedicle screw fixation.30 Second, it was unexpected that TLIF resulted in only a marginally greater fusion rate than PSF/PSI alone. Perhaps unilateral removal of the pars interarticularis resulted in increased instability over time despite an initial increase in rigidity. Additionally, it is possible that some pseudarthroses were missed on flexion–extension radiographs in the PSF/PSI only group. Although the results of this study indicate that a successful spinal fusion with good patient satisfaction can be achieved without harvesting extra ICBG or performing transverse process on-lay fusion, the authors acknowledge a few limitations. First, although we conclude that use of an iliac crest autograft may not be necessary, we did not have a control ICBG group for comparison. However, the objective of the current study was to present our experience in treating patients without the potential complications and morbidity associated with harvesting ICBG and performing transverse process fusions. We have relied on historical data to show that laminectomy bone autograft and rhBMP-2 with or without allograft is at least as good as the current standard ICBG approach. Future randomized controlled trials are now warranted to compare these two treatment options. A second limitation was that successful fusion was determined by flexion–extension plain radiographs. No technique short of surgical exploration is perfect for evaluating fusion status; therefore, in the asymptomatic patient, periodic follow-up with flexion–extension radiographs has been recommended.31 While possibly substandard in evaluating fusion status, other alternatives, such as CT scans, can be expensive, involve large doses of radiation and have not yet been proven
F.L. Acosta et al. / Journal of Clinical Neuroscience 16 (2009) 1184–1187
to be superior or cost-effective in large well-controlled trials.32–34 Finally, while no standardized questionnaires were used to assess functional status in this study, we found that the overwhelming majority of patients were satisfied with their outcome and would choose to have the same operation again if needed. Finally, although our mean of 32 months follow-up time is adequate, we acknowledge that not all patients were followed for a minimum of 2 years. We plan on following these patients closely to evaluate long-term outcomes in this cohort. References 1. Hu R, Hearn T, Yang J. Bone graft harvest site as a determinant of iliac crest strength. Clin Orthop Relat Res:252–6. 2. Younger EM, Chapman MW. Morbidity at bone graft donor sites. J Orthop Trauma 1989;3:192–5. 3. Fernyhough JC, Schimandle JJ, Weigel MC, et al. Chronic donor site pain complicating bone graft harvesting from the posterior iliac crest for spinal fusion. Spine 1992;17:1474–80. 4. Ahlmann E, Patzakis M, Roidis N, et al. Comparison of anterior and posterior iliac crest bone grafts in terms of harvest-site morbidity and functional outcomes. J Bone Joint Surg Am 2002;84-A:716–20. 5. Banwart JC, Asher MA, Hassanein RS. Iliac crest bone graft harvest donor site morbidity. A statistical evaluation. Spine 1995;20:1055–60. 6. Goulet JA, Senunas LE, DeSilva GL, et al. Autogenous iliac crest bone graft. Complications and functional assessment. Clin Orthop Relat Res:76–81. 7. Sasso RC, LeHuec JC, Shaffrey C. Iliac crest bone graft donor site pain after anterior lumbar interbody fusion: a prospective patient satisfaction outcome assessment. J Spinal Disord Tech 2005;18(Suppl.):S77–81. 8. Burkus JK, Gornet MF, Dickman CA, et al. Anterior lumbar interbody fusion using rhBMP-2 with tapered interbody cages. J Spinal Disord Tech 2002;15:337–49. 9. Gibson S, McLeod I, Wardlaw D, et al. Allograft versus autograft in instrumented posterolateral lumbar spinal fusion: a randomized control trial. Spine 2002;27:1599–603. 10. Nugent PJ, Dawson EG. Intertransverse process lumbar arthrodesis with allogeneic fresh-frozen bone graft. Clin Orthop Relat Res:107–11. 11. Weiss LE, Vaccaro AR, Scuderi G, et al. Pseudarthrosis after postoperative wound infection in the lumbar spine. J Spinal Disord 1997;10:482–7. 12. Buttermann GR, Glazer PA, Hu SS, et al. Revision of failed lumbar fusions. A comparison of anterior autograft and allograft. Spine 1997;22:2748–55. 13. Brantigan JW. Pseudarthrosis rate after allograft posterior lumbar interbody fusion with pedicle screw and plate fixation. Spine 1994;19:1271–9.. discussion 80. 14. Wimmer C, Krismer M, Gluch H, et al. Autogenic versus allogenic bone grafts in anterior lumbar interbody fusion. Clin Orthop Relat Res:122–6. 15. Yazici M, Asher MA. Freeze-dried allograft for posterior spinal fusion in patients with neuromuscular spinal deformities. Spine 1997;22:1467–71.
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16. Wang JC, Alanay A, Mark D, et al. A comparison of commercially available demineralized bone matrix for spinal fusion. Eur Spine J 2007;16:1233–40. 17. Burkus JK, Dorchak JD, Sanders DL. Radiographic assessment of interbody fusion using recombinant human bone morphogenetic protein type 2. Spine 2003;28:372–7. 18. Boden SD, Kang J, Sandhu H, et al. Use of recombinant human bone morphogenetic protein-2 to achieve posterolateral lumbar spine fusion in humans: a prospective, randomized clinical pilot trial: 2002 Volvo Award in clinical studies. Spine 2002;27:2662–73. 19. Vaccaro AR, Anderson DG, Patel T, et al. Comparison of OP-1 Putty (rhBMP-7) to iliac crest autograft for posterolateral lumbar arthrodesis: a minimum 2-year follow-up pilot study. Spine 2005;30:2709–16. 20. Aryan HE, Ames CP, Szandera B, et al. Coblation of spinal endplates in preparation for interbody spinal fusion. J Clin Neurosci 2006;13:349–52. 21. Dick IL. Iliac-bone transplantation: preliminary observations. J Bone Joint Surg Am 1946;28:1–14. 22. Arrington ED, Smith WJ, Chambers HG, et al. Complications of iliac crest bone graft harvesting. Clin Orthop Relat Res 1996;300–9. 23. Fowler BL, Dall BE, Rowe DE. Complications associated with harvesting autogenous iliac bone graft. Am J Orthop 1995;24:895–903. 24. Dimar JR, Glassman SD, Burkus KJ, et al. Clinical outcomes and fusion success at 2 years of single-level instrumented posterolateral fusions with recombinant human bone morphogenetic protein-2/compression resistant matrix versus iliac crest bone graft. Spine 2006;31:2534–40. 25. Heary RF, Schlenk RP, Sacchieri TA, et al. Persistent iliac crest donor site pain: independent outcome assessment. Neurosurgery 2002;50:510–7. 26. Sawin PD, Traynelis VC, Menezes AH. A comparative analysis of fusion rates and donor-site morbidity for autogeneic rib and iliac crest bone grafts in posterior cervical fusions. J Neurosurg 1998;88:255–65. 27. Skaggs DL, Samuelson MA, Hale JM, et al. Complications of posterior iliac crest bone grafting in spine surgery in children. Spine 2000;25:2400–2. 28. Bono CM, Lee CK. Critical analysis of trends in fusion for degenerative disc disease over the past 20 years: influence of technique on fusion rate and clinical outcome. Spine 2004;29:455–63.. discussion Z5. 29. Nasca RJ, Whelchel JD. Use of cryopreserved bone in spinal surgery. Spine 1987;12:222–7. 30. Niemeyer TK, Koriller M, Claes L, et al. In vitro study of biomechanical behavior of anterior and transforaminal lumbar interbody instrumentation techniques. Neurosurgery 2006;59:1271–7. 31. Hilibrand AS, Dina TS. The use of diagnostic imaging to assess spinal arthrodesis. Orthop Clin North Am 1998;29:591–601. 32. Brodsky AE, Kovalsky ES, Khalil MA. Correlation of radiologic assessment of lumbar spine fusions with surgical exploration. Spine 1991;16:S261–5. 33. Carreon LY, Djurasovic M, Glassman SD, et al. Diagnostic accuracy and reliability of fine-cut CT scans with reconstructions to determine the status of an instrumented posterolateral fusion with surgical exploration as reference standard. Spine 2007;32:892–5. 34. Larsen JM, Rimoldi RL, Capen DA, et al. Assessment of pseudarthrosis in pedicle screw fusion: a prospective study comparing plain radiographs, flexion/ extension radiographs, CT scanning, and bone scintigraphy with operative findings. J Spinal Disord 1996;9:117–20.
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Clinical Study
Patient satisfaction and radiographic outcomes after lumbar spinal fusion without iliac crest bone graft or transverse process fusion Frank L. Acosta a,*, Jordan M. Cloyd a, Henry E. Aryan b, Christopher P. Ames a a b
Department of Neurological Surgery, University of California, San Francisco, 505 Parnassus Avenue, M779, Box 0112, San Francisco 94143, CA, USA Division of Neurological Surgery, University of California, San Diego, CA, USA
a r t i c l e
i n f o
Article history: Received 24 October 2008 Accepted 7 December 2008
Keywords: Lumbar spinal fusion Iliac crest Bone morphogenic protein Allograft Subjective outcomes Back pain
a b s t r a c t Iliac crest bone graft (ICBG) remains the gold standard for promoting bony fusion of the spine. However, harvest-site infection and pain are two of the most significant drawbacks of using iliac crest autograft in spinal fusion procedures. The rationale for its continued use, despite these drawbacks, has been based on the relatively higher rate of fusion reported in the literature. Therefore, the objective of this study was to determine whether modern allograft and fusion-promoting materials combined with local bone graft results in acceptable fusion rates and patient satisfaction. We retrospectively reviewed the clinical, surgical, and radiographic records of 200 consecutive patients with symptomatic degenerative diseases of the lumbar spine who underwent non-revision fusion using local bone graft combined with recombinant human bone morphogenetic protein (rhBMP)-2 with or without allograft. Rates of radiographic fusion and patient satisfaction were analyzed at discharge, 6 months, and 12 months, and every year thereafter. Mean follow-up was 32 months. Fusion was performed across an average of 2.5 levels and the overall fusion rate was 97%. In patients undergoing posterior fixation only there was a 5% incidence of pseudarthrosis, while the incidence was only 0.5% for patients undergoing circumferential fixation. Overall patient satisfaction at discharge was good to excellent in over 90% of patients and did not significantly change at the 6 month, 12 month and 24 month follow-up. In conclusion, there is no significant difference in rates of spinal fusion using laminectomy bone autograft combined with rhBMP-2 with or without allograft, compared to historical controls using ICBG. Fusion rates may be further improved with the use of circumferential fixation. Patient satisfaction remained high and might be because the morbidity associated with harvesting ICBG was avoided, as was the additional muscle dissection required for the fusion of lateral transverse processes. Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction Autologous iliac crest bone graft (ICBG) remains the gold standard for promoting bony fusion in lumbar spine arthrodesis despite a limited supply and potential complications associated with harvesting the bone graft. These complications include infection, hematoma, neurovascular damage, pelvic instability and fracture as well as severe and persistent donor site pain.1,2 The incidence of morbidity associated with harvesting the ICBG ranges between 6% and 40%.2–8 To avoid the complications and disability associated with obtaining the iliac crest bone, allograft bone has also been used to promote fusion. Although allografts carry potential risks of infection, immunologic reaction, and infectious disease transmission, a recent randomized controlled trial demonstrated favorable clinical outcomes obviously without the donor site pain compared to patients fused with ICBG.9 * Corresponding author. Tel.: +1 415 353 3998; fax: +1 415 502 1320. E-mail address: [email protected] (F.L. Acosta). 0967-5868/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.jocn.2008.12.006
The rationale for the continued used of ICBG is that some investigators have claimed that allograft results in inferior fusion rates compared to iliac crest autograft.10–13 However, other clinical reports have shown similar fusion rates with use of allograft compared to ICBG14,15 and a recent animal study showed greater rates of successful fusion with demineralized bone matrix compared to autograft.16 In addition to allograft bone, some investigators have used bone morphogenetic proteins (BMPs) to promote fusion in anterior lumbar interbody fusion (ALIF)8,17 and posterolateral fusion with and without instrumentation.18–20 Modern spine fusion techniques, including allograft and osteogenic materials combined with local bone graft, may result in comparable rates of fusion and, by alleviating the need for harvesting ICBG, improved patient satisfaction. The purpose of this study is to determine whether local bone graft, combined with modern fusion-promoting agents and allograft, can result in comparable rates of radiographic lumbar spinal fusion as ICBG. We present 200 consecutive patients with symptomatic degenerative lumbar spine disease who underwent
1185
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non-revision instrumented fusion using local bone graft and recombinant human bone morphogenetic protein (rhBMP)-2 with or without allograft. Specifically, all patients were fused without ICBG and/or transverse process fusion. We hypothesize similar rates of fusion will be achieved and patient satisfaction will be greater due to reducing morbidity associated with harvesting ICBG compared to historical controls. 2. Materials and methods A retrospective review of the clinical, surgical and radiographic records of 200 consecutive patients presenting with symptomatic degenerative disease of the lumbar spine was performed (Table 1). Diagnoses were degenerative disc disease (DDD) with stenosis (106 patients), degenerative spondylolisthesis (52), spondylolysis (25) and adult degenerative scoliosis (17). The mean age was 59 (range 42–71) and there were 88 males (44%). Patients with a history of previous fusion surgery and persons judged medically unfit to undergo the surgical operation by an anesthesiologist were excluded from the study. Non-operative management of pain, including medication and epidural steroid injection, was exhausted in all patients. All surgeries were performed by the senior author (CPA). All patients underwent laminectomy followed by posterior spinal fusion (PSF). Posterior facet fusion was achieved by packing morselized laminectomy autograft through the decorticated facet joints. Local bone was harvested with a combination of Leksell and Kerrison rongeurs. All soft tissue was removed and the remaining bone ground into small morsels with a Leksell rongeur. GraftonÒ allograft (Osteotech; Eatontown, NJ, USA) was used only when minimal laminectomy bone could be acquired. Posterior spinal instrumentation (PSI) with pedicle screw-rod fixation was then performed. No patients underwent transverse process on-lay fusion. Ninety percent of patients also underwent anterior (ALIF) or tranforaminal lumbar interbody fusion (TLIF) using rhBMP-2 packed into a carbon fiber interbody graft (CougarTM System) (Depuy Spine; Raynham, MA, USA) or femoral ring allograft. All defor-
mity cases were treated with ALIF using rhBMP-2 packed into a titanium Pyramesh cage (Medtronic; Memphis, TN, USA). Radiographic evidence of fusion and patient satisfaction were analyzed at discharge, 6 months, and 12 months and then every year thereafter. Solid bony fusion was defined as lack of motion, hardware migration, fracture, or lucency on flexion–extension radiographs. Patients were asked two questions to document their level of satisfaction with the surgery: (i) what is your overall level of satisfaction with the surgery? (answer choices: poor, below average, average, good, excellent); and (ii) would you still make the same decision to have the procedure? (answer choices: yes, no). 3. Results The operative results are displayed in Table 2. A total of 130 patients underwent ALIF with PSF/PSI and were fused across a mean of 3.2 levels with a 100% fusion rate. Fifty patients were fused across 2.5 levels with TLIF and PSF/PSI with a fusion rate of 92%, while 20 patients underwent only PSF/PSI across an average of 2.3 levels and had a 90% fusion rate. There were no significant differences in fusion rates between the three procedural groups (p > 0.05). Overall fusion rate was 97% with an average of 32 months (range 6–40 months) follow-up. Four patients in the TLIF group had a pseudarthrosis: one patient had diabetes and 2 were smokers. Two patients in the PSF/PSI only group had pseudarthrosis and both were smokers. All patients in whom fusion did not occur underwent revision fusion with ALIF and posterior fixation. There were 11 perioperative complications (Table 3): 5 wound infections (2 PSF/PSI, 2 ALIF, 1 TLIF), 2 cerebrospinal fluid (CSF) leaks (1 PSF/PSI, 1 TLIF), 3 deep vein thromboses (2 ALIF, 1 TLIF), and 1 case of pneumonia (1 ALIF). Overall patient satisfaction at discharge was good to excellent in over 90% of patients (ALIF, 93%; TLIF, 94%; PSF/PSI, 91%) and did not significantly change at 6 month, 12 month or 24 month follow-up (Fig. 1A). There was no statistically significant difference in results when controlling for procedure or diagnosis. Over 90% of patients responded that they would make the same decision regarding their surgical care again and there were no significant differences among diagnoses or procedures (Fig. 1B).
Table 1 Characteristics of patients presenting with symptomatic degenerative disease of the lumbar spine Total no. of patients
200
Mean age (range) Sex Male (%) Female (%) Diagnosis DDD (%) Degenerative spondylolisthesis Spondylolysis (%) Scoliosis (%) Mean follow-up, months (range)
59 (42–71) 88 (44) 112 (56) 106 (53) 52 (26) 25 (13) 17 (9) 32 (6–40)
DDD = degenerative disc disease.
Table 3 Operative complications by surgical procedure Type of surgery
Infection
CSF leak
DVT
Pneumonia
Pseudarthrosis
Total (%)
ALIF + PSF/PSI TLIF + PSF/PSI PSF/PSI Total
2 1 2 5
0 1 1 2
2 1 0 3
1 0 0 1
0 4 2 6
5 (3.8%) 3 (6%) 5 (25%)
ALIF = anterior lumbar interbody fusion, CSF = cerebrospinal fluid, DDD = degenerative disc disease, DVT = deep vein thrombosis, PSF = posterior spine fusion, PSI = pedicle screw instrumentation, TLIF = transforaminal lumbar interbody fusion.
Table 2 Operative results based on surgical procedure Type of surgery
ALIF + PSF/PSI TLIF + PSF/PSI PSF/PSI
No. patients (%)
130 (65) 50 (25) 20 (10)
Diagnosis (%) DDD
Spondylolisthesis
Spondylosis
Scoliosis
81 (62) 18 (36) 7 (35)
25 (19) 24 (48) 3 (15)
7 (5) 8 (16) 10 (50)
17 (13) 0 0
Mean levels fused
Fusion rate
3.2 2.5 2.3
100 92 90
ALIF = anterior lumbar interbody fusion, DDD = degenerative disc disease, TLIF = transforaminal lumbar interbody fusion, PSF = posterior spine fusion, PSI = pedicle screw instrumentation.
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Fig. 1. Clinical outcomes. (A) Percentage of patients reporting a good to excellent outcome at discharge, and at 6 month, 12 month and 24 month follow-up. (B) Percentage of patients responding ‘‘yes” to the question: would you make the same decision to have the procedure again? ALIF = anterior lumbar interbody fusion; D/C = discharge, DDD = degenerative disc disease, PSF = posterior spine fusion; PSI = pedicle screw instrumentation, TLIF = transforaminal lumbar interbody fusion.
4. Discussion Since the first description of using autologous bone graft from the iliac crest to promote bony fusion in 194621, it has been recognized that there are significant complications associated with harvesting the graft. These complications include infection, hematoma, neurovascular damage, pelvic instability and fracture, abdominal herniation and peritoneal perforation.2,6,22,23 Perhaps more importantly is the persistent pain and discomfort that is caused by obtaining the autograft. Several studies have shown long-term donor site pain in 15% to 39% of patients 2 years postoperatively.3,5,6,24–27 Interestingly, patients who have an ICBG harvested for a lumbar spine fusion tend to have greater postoperative donor site pain than those needing autograft for other reasons.3 A recent prospective study by Sasso et al. revealed 31% of patients reported some level of donor site pain at 2 year follow-up while 16% reported fair or poor appearance of the graft site.7 The rationale for the continued use of ICBG despite its known morbidities is the belief that using iliac crest autograft results in a higher rate of fusion. In a recent review of the spine fusion literature since the mid-1980s, Bono and Lee report the mean fusion rate using autogenous bone was 87% while allograft fusion alone and a mixture of autograft and allograft both resulted in fusion rates of 86%.28 They conclude that allograft results in a similar rate of fusion, although their analysis includes only a few allograft patients (n = 206) compared to autograft patients (n = 4934). Butterman et al. reported on a series of 38 patients undergoing revision anterior–posterior fusions with a 100% fusion rate in those fused with autograft and 94% fused with allograft.12 Nasca and Whelchel found no significant differences in fusion rates (86.6% versus 87.0%) between autograft and allograft in their study of
152 patients.29 Wimmer et al. studied 94 consecutive patients undergoing circumferential fusion for spondylolisthesis and found a 97% rate of fusion in patients with ICBG and 92% in patients using femoral ring allograft.14 Most recently, Dimar et al. searched for evidence of pseudarthrosis using fine-cut CT scans in ICBG versus rhBMP-2 with compression-resistant matrix and found a significantly greater fusion rate in the BMP/compression-resistant matrix group compared to autograft (88% versus 73%).24 In the current study, our fusion rate of 97% overall compares favorably to the available data for fusions using ICBG and therefore provides a reasonable alternative to the current gold standard approach. Along with a successful fusion, patient satisfaction remains one of the most important outcomes for any surgery. In their review, Bono and Lee found good–excellent clinical outcomes in 76% to 78% of fusions using autologous bone only.28 Gibson et al. compared clinical outcomes in fusions with allograft versus iliac crest autograft and found that patients in the ICBG group had greater pain scores 1 year postoperatively and they attributed this to donor site pain.9 Vaccaro et al. reported a clinical success, defined as a 20% improvement in preoperative Oswestry Disability Index (ODI) scores, in 85% of patients fused with rhBMP-7 compared to only 64% in those with iliac crest bone at 2-year follow-up.19 In our study, the overwhelming majority of patients reported a good–excellent outcome, regardless of procedure or diagnosis. Furthermore, over 90% of patients responded that they would make the same decision regarding their surgical care at all times and for all procedures. One reason patient satisfaction may have been so high in our study is that the pain and discomfort associated with harvesting the ICBG, as well as the additional muscle dissection required for fusion of the transverse processes, were avoided. The results of our study pose a few interesting findings. First, ALIF was found to be superior to TLIF in terms of fusion rate, although these differences were not statistically significant. It is possible that the anterior approach allows greater fusion surface preparation and provides greater stability due to the larger cages used. One biomechanical comparison of the two approaches found that ALIF provided greater segmental stability in flexion–extension and axial rotation compared to TLIF, although these differences were minor after pedicle screw fixation.30 Second, it was unexpected that TLIF resulted in only a marginally greater fusion rate than PSF/PSI alone. Perhaps unilateral removal of the pars interarticularis resulted in increased instability over time despite an initial increase in rigidity. Additionally, it is possible that some pseudarthroses were missed on flexion–extension radiographs in the PSF/PSI only group. Although the results of this study indicate that a successful spinal fusion with good patient satisfaction can be achieved without harvesting extra ICBG or performing transverse process on-lay fusion, the authors acknowledge a few limitations. First, although we conclude that use of an iliac crest autograft may not be necessary, we did not have a control ICBG group for comparison. However, the objective of the current study was to present our experience in treating patients without the potential complications and morbidity associated with harvesting ICBG and performing transverse process fusions. We have relied on historical data to show that laminectomy bone autograft and rhBMP-2 with or without allograft is at least as good as the current standard ICBG approach. Future randomized controlled trials are now warranted to compare these two treatment options. A second limitation was that successful fusion was determined by flexion–extension plain radiographs. No technique short of surgical exploration is perfect for evaluating fusion status; therefore, in the asymptomatic patient, periodic follow-up with flexion–extension radiographs has been recommended.31 While possibly substandard in evaluating fusion status, other alternatives, such as CT scans, can be expensive, involve large doses of radiation and have not yet been proven
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to be superior or cost-effective in large well-controlled trials.32–34 Finally, while no standardized questionnaires were used to assess functional status in this study, we found that the overwhelming majority of patients were satisfied with their outcome and would choose to have the same operation again if needed. Finally, although our mean of 32 months follow-up time is adequate, we acknowledge that not all patients were followed for a minimum of 2 years. We plan on following these patients closely to evaluate long-term outcomes in this cohort. References 1. Hu R, Hearn T, Yang J. Bone graft harvest site as a determinant of iliac crest strength. Clin Orthop Relat Res:252–6. 2. Younger EM, Chapman MW. Morbidity at bone graft donor sites. J Orthop Trauma 1989;3:192–5. 3. Fernyhough JC, Schimandle JJ, Weigel MC, et al. Chronic donor site pain complicating bone graft harvesting from the posterior iliac crest for spinal fusion. Spine 1992;17:1474–80. 4. Ahlmann E, Patzakis M, Roidis N, et al. Comparison of anterior and posterior iliac crest bone grafts in terms of harvest-site morbidity and functional outcomes. J Bone Joint Surg Am 2002;84-A:716–20. 5. Banwart JC, Asher MA, Hassanein RS. Iliac crest bone graft harvest donor site morbidity. A statistical evaluation. Spine 1995;20:1055–60. 6. Goulet JA, Senunas LE, DeSilva GL, et al. Autogenous iliac crest bone graft. Complications and functional assessment. Clin Orthop Relat Res:76–81. 7. Sasso RC, LeHuec JC, Shaffrey C. Iliac crest bone graft donor site pain after anterior lumbar interbody fusion: a prospective patient satisfaction outcome assessment. J Spinal Disord Tech 2005;18(Suppl.):S77–81. 8. Burkus JK, Gornet MF, Dickman CA, et al. Anterior lumbar interbody fusion using rhBMP-2 with tapered interbody cages. J Spinal Disord Tech 2002;15:337–49. 9. Gibson S, McLeod I, Wardlaw D, et al. Allograft versus autograft in instrumented posterolateral lumbar spinal fusion: a randomized control trial. Spine 2002;27:1599–603. 10. Nugent PJ, Dawson EG. Intertransverse process lumbar arthrodesis with allogeneic fresh-frozen bone graft. Clin Orthop Relat Res:107–11. 11. Weiss LE, Vaccaro AR, Scuderi G, et al. Pseudarthrosis after postoperative wound infection in the lumbar spine. J Spinal Disord 1997;10:482–7. 12. Buttermann GR, Glazer PA, Hu SS, et al. Revision of failed lumbar fusions. A comparison of anterior autograft and allograft. Spine 1997;22:2748–55. 13. Brantigan JW. Pseudarthrosis rate after allograft posterior lumbar interbody fusion with pedicle screw and plate fixation. Spine 1994;19:1271–9.. discussion 80. 14. Wimmer C, Krismer M, Gluch H, et al. Autogenic versus allogenic bone grafts in anterior lumbar interbody fusion. Clin Orthop Relat Res:122–6. 15. Yazici M, Asher MA. Freeze-dried allograft for posterior spinal fusion in patients with neuromuscular spinal deformities. Spine 1997;22:1467–71.
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