Effects of autogenous bone graft impaction and tricalcium phosphate on anterior interbody fusion in the porcine lumbar spine

Background Impaction grafting can be achieved inside the spinal fusion cages, but its effect on bone graft incorporation and spinal fusion has not been studied. Animals and methods We investigated the effect of impaction grafting on the bone graft healing and fusion potential of beta-tricalcium phosphate (beta-TCP) inside the carbon fiber reinforced spinal fusion device (Brantigan cage) in 10 Danish landrace pigs. Lumbar spine interbody fusion of L2/3, L4/5 and L6/7 using carbon fiber cages was performed on each pig. Cages filled with either loosely-packed autologous iliac bone graft, rod-impacted autologous bone graft or beta-TCP were randomly distributed to the three fusion levels. Half of the animals were followed for 8 weeks, and the other half for 16 weeks. Results Radiographs and CT evaluations showed that autograft levels had significantly better results than beta-TCP levels (p<0.001 Fisher's Exact Test). However, the difference between impacted and loosely-packed levels was not significant. Histomorphometric analysis showed no difference between the loosely-packed and impacted cages with regard to bone volume, bone marrow volume, cartilage and fibrous tissue volume, while both of the autograft levels differed from the beta-TCP levels in all of the aforementioned parameters. Fluorochrome studies demonstrated that bone mineral apposition rate was significantly higher in the impacted cages than in the loosely-packed cages at 16 weeks. Interpretation Manual impaction of autologous bone graft into the carbon fiber cages resulted in a faster mineral apposition rate by 16 weeks. Bone ingrowth and spinal fusion were not influenced by impaction grafting.     

Current status of bone graft options for anterior interbody fusion of the cervical and lumbar spine

Anterior cervical discectomy and fusion (ACDF) and anterior lumbar interbody fusion (ALIF) are common surgical procedures for degenerative disc disease of the cervical and lumbar spine. Over the years, many bone graft options have been developed and investigated aimed at complimenting or substituting autograft bone, the traditional fusion substrate. Here, we summarise the historical context, biological basis and current best evidence for these bone graft options in ACDF and ALIF.     

后路椎体间打压植骨融合治疗腰椎失稳的临床观察

目的:探讨后路椎体间打压植骨融合术治疗腰椎失稳症的临床疗效和适应证。方法:分析2001年1月至2008年7月95例腰椎失稳行后路椎体间打压植骨融合术的患者,其中男41例,女54例;年龄45～76岁,平均59岁。其中单节段68例,2节段22例,3节段5例,共127个椎间隙。术中椎管及患侧神经根彻底减压,由患侧切除椎间盘组织,大范围刮除软骨板直至终板,使用切除的椎板等骨质打压植骨,配合椎弓根螺钉内固定。观察手术前后的症状体征并进行JOA评分;通过腰椎X线片测量手术前后椎间高度变化并根据SUK方法观察植骨融合情况。结果:95例患者均获得随访,时间12～90个月,平均44.8个月。术后临床症状明显缓解或消失,127个椎间隙均获融合,未发生植入骨移位及严重并发症。影像学示术后椎间高度较术前显著增加。术后8周JOA评分为(25.1±2.8)分,最终随访时(24.8±3.2)分,与术前(11.3±3.3)分相比,差异有统计学意义(P0.001)。结论:后路椎体间打压植骨融合术可作为治疗腰椎失稳的有效方法之一,适用范围广,尤其适用于老年腰椎退变性不稳。     

后路椎体间打压植骨治疗老年人腰椎退变性疾病的临床报道

目的 探讨椎体间微粒骨打压植骨治疗老年人腰椎退变性疾病的手术技术和初期临床疗效报道。方法 本组为2002年5月～2004年8月在对28位60岁以上老年人腰椎退变性疾病患者手术治疗的同时进行椎体间微粒骨打压植骨融合。观察手术前后的症状、体征、影像学上的腰椎前凸角、椎间隙高度指数的变化,以及手术后CT检查椎体间植骨面积,同时随访6～26个月观察初期临床疗效和融合率。结果 几乎所有患者手术后原症状和体征均得到缓解,影像学上的腰椎前凸角、椎间隙高度指数都有明显恢复,手术后6～26个月,脊柱融合率达到96．4％。没有发生植入骨的吸收、移位和沉陷。并发症主要为术中硬脊膜撕裂、神经根牵拉以及出血多等。结论 后路减压、固定、椎体间微粒骨打压植骨融合治疗老年人腰椎退变性疾病早期临床疗效满意。     

腰椎前路椎间自体骨植骨后椎间隙高度变化的研究

目的回顾性研究腰椎前路椎间自体骨植骨后临床与放射学的长期结果,观察自体骨塌陷的发生率及程度,评价与神经根疼痛复发的关系. 方法对67例采用自体髂骨进行L4,5椎间融合的患者进行了长期随访,平均随访时间为14年(2.5～32年).依据伸屈位X线片有无活动,X线断层片上植骨块与椎体是否存在透明线,以及有无骨性连接来判断椎间是否融合,同时测量椎间隙的高度;随访时根据患者的主述,检查患者有无下肢神经根刺激症状. 结果在67例随访患者中,64例获得了骨性融合,融合率为96%,融合发生时间为5～14个月,平均9个月.在融合的64例中,55例术后植骨块出现塌陷,发生率为86%,9例没有出现塌陷(14%).在出现植骨块塌陷的55例中,术前椎间隙高度为(12.1±2.9) mm,手术后增加到(16.2±1.9) mm,至完全骨性融合时,椎间隙高度下降为(12.9±2.7) mm,与最初的椎间隙高度没有显著差别.骨性融合后,椎间隙高度再无明显变化,最后随访时的高度为(12.6±2.3) mm.在整个随访过程中,95%的患者(52例)没有复发神经根性疼痛. 结论 L4-5单节段椎间自体3面皮质骨植骨后,容易出现植骨块塌陷,但是,椎间隙最终的高度很少低于术前最初的高度,且不会造成神经根疼痛的复发.     

Posterior lumbar interbody fusion with an autogenous iliac crest bone graft in the treatment of pyogenic spondylodiscitis

There are few reports on the treatment of pyogenic lumbar spondylodiscitis through the posterior approach using a single incision. Between October 1999 and March 2003 we operated on 18 patients with pyogenic lumbar spondylodiscitis. All underwent posterior lumbar interbody fusion using an autogenous bone graft from the iliac crest and pedicle screws via a posterior approach. The clinical outcome was assessed using the Frankel neurological classification and the criteria of Kirkaldy-Willis. Under the Frankel classification, two patients improved by two grades (C to E), 11 by one grade, and five showed no change. The Kirkaldy-Willis functional outcome was excellent in five patients, good in ten and fair in three. Bony union was confirmed six months after surgery in 17 patients, but in one patient this was not achieved until two years after operation. The mean lordotic angle before operation was 20 degrees (-2 degrees to 42 degrees ) and the mean lordotic angle at the final follow-up was 32.5 degrees (17 degrees to 44 degrees ). Two patients had a superficial wound infection and two a transient root injury. Posterior lumbar interbody fusion with an autogenous iliac crest bone graft and pedicle screw fixation via a posterior approach can provide satisfactory results in pyogenic spondylodiscitis.     

Biomechanical comparison of anterior lumbar interbody fusion and transforaminal lumbar interbody fusion

STUDY DESIGN: An in vitro biomechanical comparison of 2 fusion techniques, anterior lumbar interbody fusion (ALIF) and transforaminal lumbar interbody fusion (TLIF), on cadaveric human spines. OBJECTIVE: To compare the immediate construct stability, in terms of range of motion (ROM) and neutral zone, of ALIF, including 2 separate approaches, and TLIF procedures with posterior titanium rod fixation. SUMMARY OF BACKGROUND DATA: Both ALIF and TLIF have been used to treat chronic low back pain and instability. In many cases, the choice between these 2 techniques is based only on personal preference. No biomechanical performance comparison between these 2 fusion techniques is available to assist surgical decision. METHODS: Twelve cadaveric lumbar motion segments were loaded sinusoidally at 0.05 Hz and 5 Nm in unconstrained axial rotation, lateral bending and flexion extension. Specimens were randomly divided into 2 groups with 6 in each group. One group was assigned for TLIF whereas the other group for ALIF. In the ALIF group, there were 3 steps. First, the lateral ALIF procedure with the anterior longitudinal ligament (ALL) intact was performed. Afterwards, the ALL was cut without removing the ALIF cage. Finally, another appropriately sized ALIF cage was inserted anteriorly. Biomechanical tests were conducted after each step. RESULTS: In the ALIF group, the lateral ALIF and subsequent anterior ALIF reduced segmental motion significantly (P=0.03) under all loading conditions. Removing the ALL increased ROM by 59% and 142% in axial rotation and flexion extension, respectively (P=0.03). The anterior ALIF approach was able to achieve similar biomechanical stability of the lateral approach in lateral bending and flexion extension (P>0.05) under all loading conditions. The TLIF procedure significantly reduced the range of motion compared with the intact state (P=0.03). However, no statistical difference was detected between the TLIF group and the ALIF group (P>0.05). CONCLUSIONS: Both ALIF and TLIF procedures combined with posterior instrumentation significantly improved construct stability of intact spinal motion segments. However, there was no statistical difference between these 2 fusion techniques. The 2 ALIF approaches (lateral and anterior) also had similar construct stability even though anterior longitudinal ligament severing significantly reduced stability.     

Autogenic versus allogenic bone grafts in anterior lumbar interbody fusion

Between 1987 and 1993, 94 consecutive patients with painful spondylolisthesis underwent combined anterior and posterior fusion. The average age at operation was 40 years (range, 16-65 years). Posterior fusion was performed in all patients using pedicle screw systems, and anterior fusion was accomplished with autogenic or allogenic bone grafts. Patients retrospectively were assigned to two groups. In Group 1, anterior fusion was performed with autogenic bone grafts harvested from the iliac crest (n = 65; 146 segments) and in Group 2 allogenic bone grafts were taken from femoral heads (n = 39; 86 segments). The incidence of pseudarthrosis was evaluated on lateral tomograms 24 months after surgery. The mean clinical followup time was 4 years (range, 3-8 years). Pseudarthrosis was found in seven fused levels (3%) managed with autogenic bone grafts (Group 1) and in seven patients (8%) managed with allogenic bone grafts (Group 2). This incidence of pseudarthrosis was not significantly different between the two groups. Considering the possible complications associated with harvesting iliac crest bone, the use of allogenic bone appears justified.     

Anterior interbody fusion of the lumbar spine

Anterior interbody fusion of the lumbar spine by the extraperitoneal technique was performed in 47 patients with incapacitating low-back pain due to spondylolisthesis (26 patients) or disc degeneration (21 patients). The mean age was 38.2 years. Forty-five patients were re-examined 2--6 years postoperatively. According to the patients' own evaluation at follow-up, 53 per cent were free or almost free of back pain, 29 per cent were improved, 11 per cent unchanged and 7 per cent felt that the condition had deteriorated. Non-union occurred in nine patients, but among these three were free of pain, four were better and two were worse than before operation. The results do not seem to be correlated with age, sex, duration of pain before operation, degree of slipping in spondylolisthesis or the length of time out of work before surgery. It is concluded that this method may be worth continuing, but the patients should be selected with care.     

A cost analysis of bone morphogenetic protein versus autogenous iliac crest bone graft in single-level anterior lumbar fusion

An economic model was developed to compare costs of stand-alone anterior lumbar interbody fusion with recombinant human bone morphogenetic protein 2 on an absorbable collagen sponge versus autogenous iliac crest bone graft in a tapered cylindrical cage or a threaded cortical bone dowel. The economic model was developed from clinical trial data, peer-reviewed literature, and clinical expert opinion. The upfront price of bone morphogenetic protein (3380 dollars) is likely to be offset to a significant extent by reductions in the use of other medical resources, particularly if costs incurred during the 2 year period following the index hospitalization are taken into account.     

The use of beta-tricalcium phosphate and bone marrow aspirate as a bone graft substitute in posterior lumbar interbody fusion

Purpose

Due to the disadvantages of iliac crest bone and the poor bone quality of autograft gained from decompression surgery, alternative filling materials for posterior lumbar interbody fusion cages have been developed. β-Tricalcium phosphate is widely used in cages. However, data regarding the fusion rate of β-TCP assessed by computer tomography are currently not available.

Materials

A prospective clinical trial involving 34 patients (56.7 years) was performed: 26 patients were treated with single-level, five patients double-level and three patients triple-level PLIF filled with β-TCP and bone marrow aspirate perfusion, and additional posterior pedicle screw fixation. Fusion was assessed by CT and X-rays 1 year after surgery using a validated fusion scale published previously. Functional status was evaluated with the visual analogue scale and the Oswestry Disability Index before and 1 year after surgery.

Results

Forty-five levels in 34 patients were evaluated by CT and X-ray with a follow-up period of at least 1 year. Clinically, the average ODI and VAS for leg and back scores improved significantly (P < 0.001). CT assessment revealed solid fusion in 12 levels (26.67 %) and indeterminate fusion in 15 levels (34.09 %). Inadequate fusion (non-union) was detected in 17 levels (38.63 %).

Conclusion

The technique of PLIF using β-TCP yielded a good clinical outcome 1 year after surgery, however, a high rate of pseudoarthrosis was found in this series therefore, we do not recommend β-TCP as a bone graft substitute using the PLIF technique.     

Posterior and anterior lumbar interbody fusion

Posterior Lumbar Interbody Fusion (PLIF) may be indicated for intractable back pain, as it maintains adequate distraction of the intervertebral space thus relieving pressure on the nerve root. Iliac crest autografts, allografts and porous metallic cages are used.Success rates of above 90% have been reported, but complications due to the operative approach have been described. While biomechanically PLIF is superior to simple disc excision in relieving intractable back pain, the procedure is technically difficult in the presence of scar tissue from previous surgery. A proper understanding of operative principles and appropriate patient selection is essential to achieve good results. As an alternative technique, Anterior Lumbar Interbody Fusion (ALIF) has advocates.     

Containment and stabilization of bone graft in anterior lumbar interbody fusion: the role of the Hartshill Horseshoe cage

The Hartshill Horseshoe cage is a titanium implant that is inserted after removal of the disc in anterior lumbar interbody fusion. The authors use corticocancellous iliac crest graft, which is contained within the confines of the implant. The cage and the motion segment are stabilized by inserting screws into the adjacent vertebral bodies through holes in the implant. Between 1995 and 1997, 27 patients had this implant inserted. Minimum follow-up was 2.1 years (mean: 2.9 years). Patients were assessed using the Oswestry disability index, a core set of six questions, a pain drawing, and psychometrically using the Zung Depression Scale and the Modified Somatic Perception Questionnaire. The patients' subjective assessment was also obtained. Twenty-one patients (77.8%) improved significantly on the Oswestry disability index and 22 patients (81.5%) improved by subjective assessment using the "core set" of six questions. There was no evidence of pseudarthrosis, loosening, or osteolysis around the implant or the screws. The cage prevents graft extrusion, collapse, or sinkage through the endplates. The normal lumbar lordosis is restored and, by restoring normal intervertebral disc space height, the Horseshoe opens up the neural foraminae. This cage stabilizes the motion segments and secures the graft, preventing micromotion at the graft vertebral body interface and providing a conducive environment for fusion.     

后路腰椎间融合与经椎间孔腰椎间融合治疗单纯腰椎不稳的对比研究

[目的]对后路腰椎间融合(Posterior Lumbar Interbody Fusion,PLIF)及经椎间孔腰椎间融合(Transforami-nal Lumbar Interbody Fusion,TLIF)治疗单纯腰椎不稳的手术创伤、并发症及术后疗效进行比较。[方法]将2006年2月～2009年7月收治的单纯腰椎不稳患者采用随机数字表法将患者分为PLIF组(110例)、TLIF组(108例)。术前评估两组患者一般资料差异无统计学意义,具有可比性。分别对两组患者的手术创伤、术中并发症及功能恢复情况进行比较。[结果]术后随访时间14～36个月,平均21个月。手术时间:PLIF组为(125.6±45)min,TLIF组为(124.9±44)min(P>0.05);失血量:PLIF组为(1 000±450)ml,TLIF组为(995±405)ml(P>0.05);术中并发症:PLIF组为3例,TLIF组为0例(P<0.05);术后优良率:PLIF组为93.6%,TLIF组为94.4%(P>0.05);术后融合率:PLIF组为96.4%,TLIF组为98.1%(P>0.05);JOA评分:PLIF组为14.5...     

Posterolateral lumbar spine fusion with INFUSE bone graft.

BACKGROUND CONTEXT: INFUSE has been proven effective in conjunction with threaded cages and bone dowels for single-level anterior lumbar interbody fusion (ALIF). The published experience with posterolateral fusion, although encouraging, utilizes a significantly higher dose and concentration of recombinant human bone morphogenic protein-2 (rhBMP-2) and a different carrier than the commercially available INFUSE. PURPOSE: To present an assessment of fusion rate for posterolateral spine fusion with INFUSE Bone Graft. STUDY DESIGN/SETTING: Retrospective review of patients treated using INFUSE in posterolateral spine fusion in a single institution. PATIENT SAMPLE: 91 patients with minimum 2-year follow-up who underwent posterolateral spine fusion using INFUSE as an iliac crest bone graft (ICBG) substitute. OUTCOME MEASURES: Fusion rate based on fine-cut computed tomographic (CT) scans with sagittal and coronal reconstructions. METHODS: Fusion was performed using one large INFUSE kit (12 mg rhBMP-2, 1.5 mg/mL), which was prepared according to the manufacturer's instructions. The INFUSE sponge was wrapped around the local bone or graft extender and placed over the decorticated surfaces in the lateral gutters. Postoperative CT scans with reconstructions were reviewed by two independent orthopedic spine surgeons. CT scans of a comparison group of 35 patients who underwent primary single-level posterolateral fusion with ICBG were also reviewed. RESULTS: The overall group had a mean 4.38 CT fusion grade and a 6.6% nonunion rate. Primary one-level fusion cases (n=48) had a mean 4.42 fusion grade a 4.2% nonunion rate. Primary multilevel fusions (n=27) had a mean 4.65 CT grade and no nonunions detected. Assessment of the 35 primary one-level ICBG control cases demonstrated a mean CT grade of 4.35 and a nonunion rate of 11.4%. In the 16 cases of revision for prior nonunion, mean CT grade was 3.81 and 4 subjects had nonunions. Additional subgroup analysis showed that smokers (n=14) had a mean 4.32 CT grade with no nonunions. Men had a mean 4.04 CT grade and an 11.1% nonunion rate compared with a mean 4.61 CT grade and 3.6% nonunion rate in women. This difference was statistically significant (p=.036). No significant differences in fusion rate were observed based upon the specific graft extender used (p=.200). CONCLUSIONS: Posterolateral spine fusion involves a more difficult healing environment with a limited surface for healing, a gap between transverse processes and the milieu of distractive forces. Historically, only ICBG has been able to overcome these challenges and reliably generate a successful posterolateral lumbar spine fusion. In contrast to prior studies, clinically available INFUSE delivers only 12 mg rhBMP-2 at a concentration of 1.5 mg/mL. Despite the lower dose and concentration of rhBMP-2, this study suggests that fusion success with INFUSE is equivalent to ICBG for posterolateral spine fusion. As with ICBG, development of solid fusion or nonunion is a multifactorial process. The use of INFUSE is not a substitute for proper surgical technique or optimization of patient-related risk factors. Additional studies are needed to determine the incremental benefit of a greater rhBMP-2 dose or use of alternative carriers for posterolateral fusion. Finally, correlation between radiographic findings and clinical outcomes, and a cost-benefit analysis are needed. Despite these issues, this study presents compelling evidence that commercially available INFUSE is an effective ICBG substitute for one- and two-level posterolateral instrumented spine fusion.