Bone Union Rate Following Instrumented Posterolateral Lumbar Fusion: Comparison between Demineralized Bone Matrix versus Hydroxyapatite

STUDY DESIGN: Retrospective study. PURPOSE: To compare the union rate of posterolateral lumbar fusion (PLF) using demineralized bone matrix (DBM) versus hydroxyapatite (HA) as bone graft extender. OVERVIEW OF LITERATURE: To our knowledge, there has been no clinical trial to compare the outcomes of DBM versus HA as a graft material for PLF. METHODS: We analyzed prospectively collected data from consecutive 79 patients who underwent instrumented PLF. Patients who received DBM were assigned to group B (n=38), and patients who received HA were assigned into group C (n=41). The primary study outcome was fusion rate assessed with radiographs. The secondary outcomes included pain intensity using a visual analogue scale, functional outcome using Oswestry disability index score, laboratory tests of inflammatory profiles and infection rate. RESULTS: One year postoperatively, bone fusion was achieved in 73% in group B and 58% in group C without significant difference between the groups (p=0.15). There were no differences between the groups with respect to secondary outcomes. CONCLUSIONS: DBM would provide noninferior outcomes compared to the HA as a fusion material for PLF, and could be a notable alternative.

Recombinant Human Bone Morphogenetic Protein-2 in Posterolateral Spinal Fusion: What's the Right Dose?

STUDY DESIGN: Single center retrospective cohort analysis. PURPOSE: The goal was to evaluate the influence of varying amount of recombinant human bone morphogenetic protein 2 (rhBMP-2) per level on fusion rates and complications in posterolateral spinal fusions. OVERVIEW OF LITERATURE: rhBMP-2 has been utilized for lumbar posterolateral fusions for many years. Initial rhBMP-2 recommendations were 20 mg/level of fusion. Dose and concentration per level in current studies vary from 4.2 to 40 mg and 1.5 to 2.0 mg/mL, respectively. Variable fusion and complication rates have been reported. METHODS: Patients (n=1,610) undergoing instrumented lumbar spinal fusion (2003-2009) with utilization of rhBMP-2 were retrospectively evaluated. Patient demographics, body mass index (BMI), comorbidities, number of levels, associated interbody fusion, and types of bone void filler were analyzed. Fusions rates and nonunions were subdivided into number of levels and amount of rhBMP-2 used per level. RESULTS: Patients (n=559) were evaluated with 58.5% females having an average age of 63 years, BMI of 31 kg/m2. Number of levels fused ranged from 1 to 8. rhBMP-2 averaged 7.3 mg/level (range, 1.5-24 mg/level) based upon length of collagen sponge in relation to length of fusion levels. Patients with non-union formation had lower rhBMP-2 dose per level (p=0.016). A significant difference in non-union rate was found between patients undergoing fusion with 6 mg/level (9.1% vs. 2.4%, χ2=0.012). No significant differences were noted between 6-11.9 mg/level and ≥12 mg/level. No threshold was found for seroma formation or bone overgrowth. CONCLUSIONS: Previous recommendation of 20 mg/level of rhBMP-2 is more than what is required for predictable fusion rates of 98%. No dose related increase of infection, seroma formation, and bone overgrowth has been found. In order to provide variable dosing and cost reduction, industry generated rhBMP-2 kit size should be optimized.

Recombinant Human Bone Morphogenetic Protein-2 in Posterolateral Spinal Fusion: What's the Right Dose?

STUDY DESIGN: Single center retrospective cohort analysis. PURPOSE: The goal was to evaluate the influence of varying amount of recombinant human bone morphogenetic protein 2 (rhBMP-2) per level on fusion rates and complications in posterolateral spinal fusions. OVERVIEW OF LITERATURE: rhBMP-2 has been utilized for lumbar posterolateral fusions for many years. Initial rhBMP-2 recommendations were 20 mg/level of fusion. Dose and concentration per level in current studies vary from 4.2 to 40 mg and 1.5 to 2.0 mg/mL, respectively. Variable fusion and complication rates have been reported. METHODS: Patients (n=1,610) undergoing instrumented lumbar spinal fusion (2003-2009) with utilization of rhBMP-2 were retrospectively evaluated. Patient demographics, body mass index (BMI), comorbidities, number of levels, associated interbody fusion, and types of bone void filler were analyzed. Fusions rates and nonunions were subdivided into number of levels and amount of rhBMP-2 used per level. RESULTS: Patients (n=559) were evaluated with 58.5% females having an average age of 63 years, BMI of 31 kg/m2. Number of levels fused ranged from 1 to 8. rhBMP-2 averaged 7.3 mg/level (range, 1.5-24 mg/level) based upon length of collagen sponge in relation to length of fusion levels. Patients with non-union formation had lower rhBMP-2 dose per level (p=0.016). A significant difference in non-union rate was found between patients undergoing fusion with 6 mg/level (9.1% vs. 2.4%, χ2=0.012). No significant differences were noted between 6-11.9 mg/level and ≥12 mg/level. No threshold was found for seroma formation or bone overgrowth. CONCLUSIONS: Previous recommendation of 20 mg/level of rhBMP-2 is more than what is required for predictable fusion rates of 98%. No dose related increase of infection, seroma formation, and bone overgrowth has been found. In order to provide variable dosing and cost reduction, industry generated rhBMP-2 kit size should be optimized.

Comparison of Posterior Lumbar Interbody Fusion and Posterolateral Lumbar Fusion in Monosegmental Vacuum Phenomenon within an Intervertebral Disc

STUDY DESIGN: Retrospective. PURPOSE: To compare the clinical and radiological outcomes of posterolateral lumbar interbody fusion (PLIF) and posterolateral lumbar fusion (PLF) in monosegmental vacuum phenomenon within an intervertebral disc. OVERVIEW OF LITERATURE: The vacuum phenomenon within an intervertebral disc is a serious form of degenerative disease that destabilizes the intervertebral body. Outcomes of PLIF and PLF in monosegmental vacuum phenomenon are unclear. METHODS: Monosegmental instrumented PLIF and PLF was performed on 84 degenerative lumbar disease patients with monosegmental vacuum phenomenon (PLIF, n=38; PLF, n=46). Minimum follow-up was 24 months. Clinical outcomes of leg and back pain were assessed using visual analogue scales for leg pain (LVAS) and back pain (BVAS), and the Oswestry disability index (ODI). The radiographic outcome was the estimated bony union rate. RESULTS: LVAS, BVAS, and ODI improved in both groups. There was no significant difference in the degree of these improvements between PLIF and PLF patients (p>0.05). Radiological union rate was 91.1% in PLIF group and 89.4% in PLF group at postoperative 24 months (p>0.05). CONCLUSIONS: No significant differences in clinical results and union rates were found between PLIF and PLF patients. Selection of the operation technique will reflect the surgeon's preferences and patient condition.

Pseudarthrosis at L5-S1 after Posterolateral Lumbar Fusion

STUDY DESIGN: This is a retrospective study. OBJECTIVES: We wanted to investigate the rate of pseudarthrosis at L5-S1 after posterolateral fusion only for degenerative lumbar spinal disease, and to determine the radiological findings that help diagnose pseudarthrosis. SUMMARY OF THE LITERATURE REVIEW: The pseudarthrosis rate at L5-S1 is much higher than that at the other lumbar segments. However, there have been few studies for the rate and risk factors of pseudarthrosis at L5-S1. MATERIALS AND METHODS: A total of 88 patients who underwent pedicle screw instrumentation and posterolateral lumbar fusion were evaluated with a minimum of 1-year follow up. Bony union was evaluated by the bony fusion mass, the angulation on the flexion-extension radiographs and the radiolucent zone around the pedicle screws. The patients' age, bony mineral density, the number of fused segments and lumbar lordosis were evaluated for their association with pseudarthrosis at L5-S1. RESULTS: Pseudarthrosis developed in 22 patients at L5-S1 and in 8 patients at other levels. The change of angulation on the flexion-extension radiographs at the last follow-up was 5.2degrees in the pseudarthrosis group and 1.7degrees in the fusion group (P=0.3). A radiolucent zone of the sacral screws was noted in 10 patients; in 7 of the 22 patients in the pseudarthrosis group and in 3 of the 66 patients in the fusion group. The average age, the mean number of levels fused and the bone mineral density were similar in both groups. Lumbar lordosis was not associated with the development of pseudarthrosis at L5-S1. CONCLUSION: The pseudarthrosis rate was significantly higher at L5-S1 than that at the other lumbar segments following instrumented posterolateral fusion. Pseudarthrosis was closely related to hypermobile angulation (> or =5degrees) on the flexion-extension radiographs and a radiolucent zone around the sacral screws.

Osteogenetic ability of calcium sulfate applied in rabbit lumbar spinal fusion model / 中国矫形外科杂志

[Objective]To investigate the osteogenetic ability of calcium sulfate applied alone by comparing with that of autograft harvested from ilium crest and discuss the possible osteogenetic mechanism.[Method]A rabbit lumbar posterolateral spinal fusion model was established.The left zygapophyseal joint was implanted with calcium sulfate tablet,and the right with iliac crest bone graft.Radiographic analysis and decalcified histological evaluation were performed.[Result]At 3 weeks,residual calcium sulfate tablet could not be noted by X-ray and CT scan,while autograft can't be seen,histological assessment revealed the degeneration velocity of calcium sulfate was slower than that of autograft.Ingrowth of blood vessel tissue and osteo-blast could be seen in both sides.At 6 weeks,there were no difference between both sides,histological assessment revealed cartilage formation in both sides.At 12 weeks,there was no difference by radiographic and histological assessment between both sides,proliferative bone formation was similar with lumbar body.[Conclusion]Calcium sulfate plays the similar role to iliac crest bone graft when used alone in promoting spinal fusion in rabbit model.Calcium sulfate has good osteo-conductivity,perhaps has osteo-inductivity,so is a good bone graft substitute.

Comparison Between Allograft Mixed with Local Bone and Autograft in Posterolateral Lumbar Fusion / 대한척추외과학회지

STUDY DESIGN: A prospective study. OBJECTIVES: To determine the usefulness of allograft and compare the result of allograft mixed with local bone and autograft in posterolateral lumbar fusion. SUMMARY OF LITERATURE REVIEW: Allograft is used for the purpose of spinal fusion, especially in the scoliosis surgery. In some studies allograft is not recommended in posterior lumbar spinal fusion alone. MATERIALS AND METHODS: Fifteen patients underwent one level posterolateral lumbar fusion using freeze-dried allograft mixed with local bone. We compared them with twenty four patients using autogenous iliac bone graft mixed with local bone about radiographic fusion grading, duration of fusion and clinical outcomes. RESULTS: Radiographic fusion grading of allograft was 7 cases of grade 1, 5 cases of grade 2, 3 cases of grade 3, and grading of autograft was 21 cases of grade 1, 2 cases of grade 2, 1 cases of grade 3. Bone fusion was complete after 11.1 months in allograft and 6.7 months in autograft. Clinically, there were 4 excellent, 9 good, 2 fair cases in allograft and 10 excellent, 11 good, 3 fair cases in autograft. CONCLUSIONS: Allograft was inferior to autograft in posterolateral lumbar fusion because allograft mixed with local bone reduced radiographic fusion grading and prolonged duration of bone fusion.