[Treatment of thoracolumbar burst fracture with subtotal vertebrectomy, decompression and strut grafting through posterolateral approach]

OBJECTIVE

To explore the clinical effect of subtotal vertebrectomy, decompression and strut grafting in treating thoracolumbar burst fractures through posterolateral approach via posterior midline incision.

METHODS

From May 2005 to July 2008, 14 patients with thoracolumbar burst fractures were treated with subtotal vertebrectomy, decompression and strut grafting through posterolateral approach via posterior midline incision. There were 9 males and 5 females, ranging in age from 24 to 68 years, with an average of 42.3 years. All patients were single segment fractures, of them, T11 was in 1 case, T12 in 5, L1 in 5 and L2 in 3. According to AO classification in spinal fracture, type A3 was in 5 cases, B1 in 3, B2 in 3, C1 in 2, C2 in 1. According to the ASIA classification in neurological function, grade A was in 3 cases, B in 3, C in 5, D in 2, E in 1. The height of anterior border vertebral body, volume of spinal canal and neurological function were analyzed by X-ray films, CT scanning and ASIA classification preoperative, postoperative and at final follow-up.

RESULTS

Operative time was from 3.5 to 5.5 hours with the mean of 4.0 hours; bleeding during operation was from 800 to 2 600 ml with the mean of 1 300 ml. Two cases with nerve root injury recovered without special handling after 3-6 months; 1 case with leakage of cerebrospinal fluid restored through lumbar cerebrospinal fluid drainage; 1 case with pleura tear healed through closed thoracic drainage. No iatrogenic vascular injury or infection was found. The follow-up time was from 8 to 36 months with the mean of 16.5 months. All patients had neurofunctional recovery at different degree, except that 3 patients in grade A. The height of anterior border vetebral body restored from (42.25 +/- 11.87)% preoperatively to (94.38 +/- 3.08)% postoperatively, and (92.87 +/- 3.32)% at final follow-up (P<0.05); volume of spinal canal (the actual volume of spinal canal/normal volume of spine canal) increased from (45.63 +/- 6.88)% preoperatively to (95.26 +/- 3.31)% postoperatively, and (96.13 +/- 2.56)% at final follow-up (P<0.05). Cobb angle were corrected from (25.64 +/- 4.40) degrees preoperatively to (5.80 +/- 1.14) degrees postoperatively; Cobb angle lost from 0 degrees to 6 degrees at final follow-up with (8.10 +/- 2.65) degrees. All patients obtained complete bony fusion without pseudarthrosis formation at final follow-up.

CONCLUSION

Subtotal vertebrectomy decompression and strut grafting through posterolateral approach via posterior midline incision is an effective and safe method in treating thoracolumbar burst fracture, which can restored height of intervertebral body, volume of spinal canal and physiological flexion of spinal column, and retain spinal permanent stability.

[Clinical observation of bone graft and impaction on posterior interbody fusion for lumbar instability]

OBJECTIVE

To investigate the clinical effect and indication of bone graft and impaction on posterior interbody fusion for lumbar instability.

METHODS

From January 2001 to July 2008, 95 patients with lumbar instability were treated by bone graft and impaction on posterior interbody fusion. Including 41 males and 54 females, the age from 45 to 76 years old with an average of 59 years. There were 68 cases with single level, 22 cases with two-level, 5 cases with three-level in patients, which were 127 intervertebral space altogether. The neural canal and affected side nerve root were decompressed thoroughly during operation. Resected the disc from the affected side and erased the cartilage to plate extensively combined with pedicle screw fixation, and impaction on interbody fusion with the excisional vertebral plate bone was achieved. To assess the improvement of the patients' symptom, sign, and JOA scores pre and post operatively. Meanwhile, the changes of intervertebral height from the lumbar radiographs were measured and the degrees of interbody bone fusion were evaluated according to SUK method.

RESULTS

All the 95 patients were followed up from 12 to 90 months with the mean of 44.8 months. All the clinical symptom were improved significantly or disappeared completely. All the 127 intervertebral space achieved good bone fusion. There was no displacement of bone graft and severe complication happened. According to the radiograph, all the intervertebral heights were increased obviously. The mean JOA score improved from 11.3 +/- 3.3 preoperative to 25.1 +/- 2.8 at 8 weeks postoperative; achieved 24.8 +/- 3.2 with followed up at the last time (P < 0.001).

CONCLUSION

Bone graft and impaction on posterior interbody fusion was one of the most effective methods for the lumbar instability. It has extensive range of application, and it's suitable for senile lumbar degeneration instability especially.

[Progressing study in treating discogenic low back pain]

Lumbago is a general, frequently and complicated clinical symptom. 60% to 80% in adults suffer from back pain of varying degrees. The pain causing by various pathological changes stimulateing the ache receptor in intervertebral disc is call discogenic low back pain. Along with people knowing more and more about this disease, all kinds of treatment techniques are applied in clinic. But the indication and therapeutic effects are both evidently different. Below is a summary of the therapic method about discogenic low back pain based on international and domestic reference data of recent years and the author's clinical experiences.

Harvesting local cylinder autograft from adjacent vertebral body for anterior lumbar interbody fusion: surgical technique, operative feasibility and preliminary clinical results

Autogenous iliac crest has long served as the gold standard for anterior lumbar arthrodesis although added morbidity results from the bone graft harvest. Therefore, femoral ring allograft, or cages, have been used to decrease the morbidity of iliac crest bone harvesting. More recently, an experimental study in the animal showed that harvesting local bone from the anterior vertebral body and replacing the void by a radio-opaque beta-tricalcium phosphate plug was a valid concept. However, such a concept precludes theoretically the use of posterior pedicle screw fixation. At one institution a consecutive series of 21 patients underwent single- or multiple-level circumferential lumbar fusion with anterior cages and posterior pedicle screws. All cages were filled with cancellous bone harvested from the adjacent vertebral body, and the vertebral body defect was filled with a beta-tricalcium phosphate plug. The indications for surgery were failed conservative treatment of a lumbar degenerative disc disease or spondylolisthesis. The purpose of this study, therefore, was to report on the surgical technique, operative feasibility, safety, benefits, and drawbacks of this technique with our primary clinical experience. An independent researcher reviewed all data that had been collected prospectively from the onset of the study. The average age of the patients was 39.9 (26-57) years. Bone grafts were successfully harvested from 28 vertebral bodies in all but one patient whose anterior procedure was aborted due to difficulty in freeing the left common iliac vein. This case was converted to a transforaminal interbody fusion (TLIF). There was no major vascular injury. Blood loss of the anterior procedure averaged 250 ml (50-350 ml). One tricalcium phosphate bone plug was broken during its insertion, and one endplate was broken because of wrong surgical technique, which did not affect the final outcome. One patient had a right lumbar plexopathy that was not related to this special technique. There was no retrograde ejaculation, infection or pseudoarthrosis. One patient experienced a deep venous thrombosis. At the last follow up (mean 28 months) all patients had a solid lumbar spine fusion. At the 6-month follow up, the pain as assessed on the visual analog scale (VAS) decreased from 6.9 to 4.5 (33% decrease), and the Oswestry disability index (ODI) reduced from 48.0 to 31.7 with a 34% reduction. However, at 2 years follow up there was a trend for increase in the ODI (35) and VAS (5). The data in this study suggest that harvesting a cylinder of autograft from the adjacent vertebral body is safe and efficient. Filling of the void defect with a beta-tricalcium phosphate plug does not preclude the use of posterior pedicle screw stabilization.

Biomechanical analysis of anterior poly-methyl-methacrylate reconstruction following total spondylectomy for metastatic disease

STUDY DESIGN

Three reconstruction options were evaluated biomechanically following total spondylectomy using human cadaveric spine specimens. OBJECTIVES.: To evaluate and compare the stability of combined anterior and posterior fixation incorporating poly-methyl-methacrylate with alternative accepted reconstruction techniques.

SUMMARY OF BACKGROUND DATA

Total spondylectomy represents the most radical option for decompression in metastatic spinal cord compression. Poly-methyl-methacrylate is considered a useful adjunct in spinal column stabilization and arthrodesis; however, there is little published biomechanical data to support its use in this setting.

METHODS

Ten fresh-frozen human cadaveric spines (T9-L3) were used. After intact analysis, a total spondylectomy was performed at T12. Three potential reconstruction techniques were tested for their ability to restore stiffness to the specimen: 1) multilevel posterior pedicle screw instrumentation from T10-L2; 2) anterior instrumentation (ATL Z plate II) and rib graft at T11-L1 with multilevel posterior pedicle screw instrumentation from T10-L2; and 3) anterior cement (Simplex P) and pins construct (T12) with multilevel posterior pedicle screw instrumentation from T10-L2. Each of the three potential reconstruction techniques was tested on each specimen in random order using nondestructive testing under load control.

RESULTS

Only combined stabilization techniques (e.g., anterior instrumentation and rib graft with multilevel posterior pedicle screw instrumentation and anterior cement-and-pins construct with multilevel posterior pedicle screw instrumentation) restored stiffness to a level equivalent to or higher than that of the intact spine in all loading modes (P < 0.05). Anterior cement-and-pins construct with multilevel posterior pedicle screw instrumentation provided more stability to the specimen than anterior instrumentation and rib graft with multilevel posterior pedicle screw instrumentation in compression and flexion testing (P < 0.05). Posterior instrumentation alone did not restore stiffness to the intact level in compression and flexion testing (P < 0.005).

CONCLUSIONS

Combined anterior and posterior reconstruction using a cement construct provides equal to or more stability than the intact spine in all testing modes. Posterior stabilization alone is an inferior method of reconstruction following total spondylectomy. Poly-methyl-methacrylate has the advantage over traditional anterior reconstruction techniques in that it can be inserted using a posterior approach.

Finite-Element Analysis for Lumbar Interbody Fusion Under Axial Loading

A parametric study was conducted to evaluate axial stiffness of the interbody fusion, compressive stress, and bulging in the endplate due to changes in the spacer position with/without fusion bone using an anatomically accurate and validated L2-L3 finite-element model exercised under physiological axial compression. The results show that the spacer plays an important role in initial stability for fusion, and high compressive force is predicted at the ventral endplate for the models with the spacer and fusion bone together. By varying the positioning of the spacer anteriorly along anteroposterior axis, no significant change in terms of axial stiffness, compressive stress, and bulging of the endplate are predicted for the implant model. The findings suggest that varying the spacer position in surgical situations does not affect the mechanical behavior of the lumbar spine after interbody fusion.

[Preliminary evaluation of the efficacy of transpedicular refilling of spongiosa loss with autologous grafts in thoraco-lumbar vertebral bodies using the Daniaux method]

In Orthopaedic University Clinic in Lublin there were 35 patients with thoraco-lumbar spine fractures since 1993 to 1997. In 18 operated patients fractures of vertebral bodies were reduced and bone loss refilled by autogenous morselised grafts implanted through arc's basis using Daniaux method. There were 9 L1 fractures, 6 Th12 and single one on levels of Th11, L2 and L3. Complete spinal cord injury had 5 patients and partial 13. The degree of vertebral body compression was counted using Taillard's formula preoperatively, 4 weeks, 6 and 12 months after surgery. The anterior wall of vertebral body was decline ranged from 20% to 77%, average 51.9%. There were evaluations of 7 patients 6 months from fixator removal. Presented results support the opinion that operative reconstruction of vertebral body's fracture with autologous spongiosa grafts implantation in place of bone loss gives better chance for anterior wall height reconstitution. Small loss of correction after metal fixator removal, average 7.7%, testify good graft's remodeling and sufficient durability of Daniaux's method of treatment.

1995 Volvo Award in basic sciences. The use of an osteoinductive growth factor for lumbar spinal fusion. Part I: Biology of spinal fusion

STUDY DESIGN

The histology of lumbar intertransverse process spinal fusion was studied in an experimental model in rabbits.

OBJECTIVES

To qualitatively and quantitatively analyze the sequential histology of spinal fusion using a previously validated animal model.

SUMMARY OF BACKGROUND DATA

Few previous studies have described the sequential histology during the posterolateral spinal fusion healing process using autogenous bone, and a basic understanding of the biology of this repair process is lacking.

METHODS

Fourteen adult New Zealand white rabbits underwent single-level posterolateral lumbar intertransverse process arthrodesis with autogenous iliac bone graft. Animals were killed 1-10 weeks after surgery, and the fusion masses were analyzed histologically and quantitated using a semiautomated image analysis system.

RESULTS

Three distinct phases of healing were identified (inflammatory, reparative, and remodeling) and occurred in sequence but in a delayed fashion in the central zone of the fusion mass compared with the outer transverse process zones. Membraneous bone formation, evident first at the ends of the fusion eminating from the decorticated transverse processes, was the predominant mechanism of healing. The central zone was somewhat different in that there was a period of endochondral bone formation during weeks 3 and 4 in this zone where cartilage formed and was converted to bone. Remodeling in the central zone had equilibrated with the transverse process zones by 10 weeks.

CONCLUSIONS

Lumbar intertransverse process spinal fusion is a complex process from a spatial and temporal standpoint. When autogenous bone is used as the graft material, this process critically depends on a variety of factors from the decorticated host bone and exposed marrow. The persistence of a central cartilage zone may be related to some types of nonunions and deserves future investigation. This enhanced understanding of the biology of spinal fusion with autogenous bone graft will provide a foundation for optimizing the use of osteoinductive bone growth factors in this healing process.

1995 Volvo Award in basic sciences. The use of an osteoinductive growth factor for lumbar spinal fusion. Part II: Study of dose, carrier, and species

STUDY DESIGN

Efficacy of a bovine-derived osteoinductive growth factor was studied in a rabbit model and in a nonhuman primate model of posterolateral lumbar spinal fusion.

OBJECTIVES

To determine the minimum effective dose of growth factor and the influence of different carrier material on the outcome of intertransverse process lumbar fusion.

SUMMARY OF BACKGROUND DATA

Bone morphogenetic proteins and related growth factors are becoming increasingly available in purified extract or genetically engineered forms and are capable of inducing new bone formation in vivo. Osteoinductive growth factors to enhance lumbar spinal infusion have not been well studied in models of posterolateral intertransverse process fusion. Because of the diminished potential of bone regeneration in primates (including humans) compared with phylogenetically lower animals, extrapolations regarding dose and efficacy cannot be made directly from results obtained in experiments performed on phylogenetically lower animals. Experiments on non-human primates are a critical step before attempting to use these growth factors on humans. METHODS. One hundred fifteen adult New Zealand white rabbits and 10 adult rhesus macaques underwent single level posterolateral intertransverse process lumbar spinal arthrodesis to evaluate different doses and carrier materials for a bovine-derived osteoinductive bone protein extract. Rabbit fusion masses were evaluated 5 weeks after arthrodesis by manual palpation, radiography, biomechanical testing, and light microscopy. Monkey fusion masses were evaluated 12 weeks after arthrodesis by radiography and light microscopy.

RESULTS

Successful posterolateral intertransverse process spinal fusions were achieved in the rabbit models using an osteoinductive growth factor with three different carriers (autogenous iliac bone, demineralized allogeneic bone matrix, and natural coral). There was a dose-dependent response to the osteoinductive growth factor in the rabbit model, indicating that a threshold must be overcome before bone formation is induced. The methodology for biologic enhancement of spinal fusion developed in the rabbit model transferred successfully to the rhesus monkey, where the use of the osteoinductive growth factor with a demineralized bone matrix carrier resulted in spinal fusion in 12 weeks.

CONCLUSION

These experiments provide an essential building block in the understanding of the biology of spinal fusion and the use of osteoinductive growth factors to enhance a posterolateral intertransverse process spinal fusion. The achievement of posterolateral spinal fusion in the rhesus monkey using an osteoinductive growth factor is a significant step toward the biologic enhancement of spinal fusion in humans.

Intertransverse process lumbar arthrodesis with allogeneic fresh-frozen bone graft

Nine patients were treated with ten intertransverse process lumbar spine anthrodeses using fresh-frozen crushed corticocancellous allogeneic bone as graft material. No instrumentation was used. The clinical and roentgenographic follow-up period ranged from one to three years. Seven procedures showed successful arthrodesis and three demonstrated pseudarthroses. Increased age and systemic disease were associated with an increased risk of pseudarthrosis. Persistent back pain was associated with pseudarthrosis. Compared with 58 patients treated with intertransverse process lumbar fusion with autogeneic iliac bone as graft material, the overall fusion rate is inferior: 70% versus 92%, respectively.

Lumbosacral fusion using internal fixation with a spinous process for the graft: a review of 50 patients with a five-year maximum follow-up

During a 5 year period 50 patients with chronic low back pain, with or without sciatica due to a proven lumbosacral disk lesion, underwent a spinal fusion using the Boucher method of screw fixation of the facet joints. The L-4 spinous process was excised and fashioned into an H-shape to act as the bone graft between the spinous processes so avoiding an iliac crest incision. Thus blood loss and operating time were substantially diminished. The screws maintain fixation for an 8-week period during which time the graft is "taking." Being inserted with spinous processes distracted about 1 cm the screws and the graft take the load off the painful posterior part of the annulus, and in addition, the distraction of the spinous processes enlarges the intervertebral foramina by about 1 cm thus making subsequent foraminal stenosis unlikely. Loosening of the screws after incorporation of the graft was observed in some cases, but was not considered to be clinically significant. Spinal fusion using screws for internal fixation including indications and contraindications requires careful consideration of operative technique, postoperative management and complications. The clinical evolution of 86% of the patients was rated good or fair from a clinical standpoint; 86% showed a fusion; 14% demonstrated a pseudarthrosis. Three of the 7 pseudarthrotic patients had a good clinical result. The other 4 had only a fair clinical result. Nine of the 14 patients with fair clinical results had a fusion radiologically; all 7 of the clinically unimproved had a fusion. Since the graft is placed at least 1 cm dorsal to the laminae, spinal cancal stenosis is extremely unlikely.

Complete spondylolisthesis in an infant. Treatment with decompression and fusion

A grade 4 spondylolisthesis at the level of L-4 and L-5 was detected in a 3-year-old girl who had a spastic gait and focal sensory deficit. There was no history or objective evidence of substantial spinal trauma. A deformity over the lower part of the spine had been noted at 1 year of age and the radiological lesion was more extensive than that found in classical spondylolysis. Consquently, a diagnosis of congenital spondylolisthesis is most acceptable. Treatment via combined posterior and posterolateral fusion following anterior decompression has yielded gratifying results.