Title: Apparent diffusion coefficients and T2 relaxation time measurements to evaluate disc degeneration. A quantitative MR study of young patients with previous vertebral fracture.
Source: Acta Radiologica. 42(6):585-91, 2001 Nov.
Abstract: PURPOSE: To assess the suitability of apparent diffusion coefficient (ADC) measurements to evaluate degeneration processes of the vertebral disc and to compare the results with T2 relaxation time measurements in both degenerated and normal intervertebral discs. MATERIAL AND METHODS: Fourteen young patients (8.8-20.8 years old) who had had a vertebral compression fracture at least 1 year earlier, underwent MR studies with diffusion imaging in three orthogonal directions and T2 relaxation time measurements. ADC values and T2 relaxation times of both degenerated and normal intervertebral discs were compared to the values of 20 healthy young asymptomatic control subjects. RESULTS: In the degenerated discs of patients, the ADCx and ADCy values were decreased compared to earlier determined values of healthy controls. ADC values in the z-direction in degenerated discs did not differ significantly from the values of controls. T2 relaxation times were shorter in the degenerated discs of patients compared to the values of controls. The greatest changes in both these values were observed in degenerated discs followed by discs with normal signal intensity adjacent to primary trauma area and secondary trauma area. CONCLUSION: We suggest that decreased ADC values reflect the lost integrity of the intervertebral disc. ADC measurements at MR may prove sensitive depicting of early degenerative changes in vertebral discs. _________________________________________________

Title: Post-traumatic findings of the spine after earlier vertebral fracture in young patients: clinical and MRI study. [see comments.]. Comments Comment in: Spine. 2000 Nov 1;25(21):2847-8 ; 11064537
Source: Spine. 25(9):1104-8, 2000 May 1.
Abstract: STUDY DESIGN: A study comparing magnetic resonance imaging findings of degenerative changes in intervertebral discs in young patients with previous wedge-shaped compression fracture and age-matched and sex-matched control subjects. OBJECTIVES: To find out the role of fractures in disc degeneration and to assess the clinical outcome of the patients. SUMMARY OF BACKGROUND DATA: Several experimental studies have postulated that trauma is one of the major reasons for disc degeneration. Wedge compression fractures in vertebrae of children have been considered insignificant, but this has not been verified in the literature. METHODS: Fourteen patients 8.8 to 20.8 years of age (mean, 15.5 years) with a history of wedge-shaped vertebral compression fracture at least 1 year previously (mean, 3.8 years) and asymptomatic healthy control subjects were studied by thoracolumbar spine magnetic resonance imaging. The patients also underwent a clinical examination. RESULTS: Eight (57%) of the 14 patients had disc degeneration, and seven of them had it at the trauma level. Of these 7 subjects, 6 also had endplate damage at this level. The association between endplate damage and adjacent intervertebral disc degeneration was significant (P < 0.01). Only 2 of the patients were symptomatic. In the control group, only 1 subject had disc degeneration with endplate changes and disc herniation. CONCLUSIONS: The patients had more disc degeneration than did those in the control group. Endplate injury was strongly associated with disc degeneration. No correlation between previous vertebral fracture and back pain was seen in this study. _______________________________________________
Abstract: OBJECT: Polymethylmethacrylate (PMMA) has long been used in the stabilization and reconstruction of traumatic and pathological fractures of the spine. Recently, hydroxyapatite (HA), an osteoconductive, biocompatible cement, has been used as an alternative to PMMA. In this study the authors compare the stabilizing effects of the HA product, BoneSource, with PMMA in an experimental compression fracture of L-1. METHODS: Twenty T9-L3 cadaveric spine specimens were mounted individually on a testing frame. Light-emitting diodes were placed on the neural arches as well as the base. Motion was tracked by two video cameras in response to applied loads of 0 to 6 Nm. The weight-drop technique was used to induce a reproducible compression fracture of T-11 after partially coring out the vertebra. Load testing was performed on the intact spine. postfracture, after unilateral transpedicular vertebroplasty with 7 to 10 ml of PMMA or HA, and after flexion-extension fatiguing to 5000 cycles at +/- 3 Nm. No significant difference between the HA- and PMMA cemented-fixated spines was demonstrated in flexion, extension, left lateral bending, or right and left axial rotation. The only difference between the two cements was encountered before and after fatiguing in right lateral bending (p < or = 0.05). CONCLUSIONS: The results of this study suggest that the same angular rigidity can be achieved using either HA or PMMA. This is of particular interest because HA is osteoconductive, undergoes remodeling, and is not exothermic. __________________________________________

Title: Pyogenic vertebral presenting as single spinal compression fracture: a case report and review of the literature. [Review] [16 refs]
Source: Spinal Cord. 38(10):639-44, 2000 Oct.
Abstract: STUDY DESIGN: A case report of pyogenic vertebral osteomyelitis (PVO) presenting as single collapsed vertebral body without narrowing of the intervertebral disc space, and review of the literature. OBJECTIVE: To describe an unusual case of PVO showing atypical radiological change and call attention to this condition so that others may avoid this diagnostic pitfall. SETTING: Japan. Methods: A 62-year-old diabetic woman with suspected T12 pathological fracture of malignant spinal tumor and neurological involvement received urgent anterior decompression and spinal reconstruction without biopsy. RESULTS: Anterior decompression and spinal reconstruction was performed, but histological examination of the specimen after surgery unexpectedly revealed PVO. The surgery was followed by therapy with antibiotics for 7 months. A follow-up radiograph at 5 years after surgery revealed that solid consolidation has been achieved. CONCLUSIONS: Diagnosis of PVO presenting with single spinal compression fracture is very difficult. Although the finding of the high signal intensity in the lesion equal to or higher than that of the cerebrospinal fluid on T2-weighted MR image seemed to be the most reliable diagnostic modality retrospectively, diagnosis of this type of PVO is impossible without histology. A needle biopsy before surgery is strongly recommended. [References: 16] ______________________________________________________

Title: Post-traumatic findings of the spine after earlier vertebral fracture in young patients: clinical and MRI study. [see comments.]. Comments Comment in: Spine. 2000 Nov 1;25(21):2847-8 ; 11064537
Source: Spine. 25(9):1104-8, 2000 May 1.
Abstract: STUDY DESIGN: A study comparing magnetic resonance imaging findings of degenerative changes in intervertebral discs in young patients with previous wedge-shaped compression fracture and age-matched and sex-matched control subjects. OBJECTIVES: To find out the role of fractures in disc degeneration and to assess the clinical outcome of the patients. SUMMARY OF BACKGROUND DATA: Several experimental studies have postulated that trauma is one of the major reasons for disc degeneration. Wedge compression fractures in vertebrae of children have been considered insignificant, but this has not been verified in the literature. METHODS: Fourteen patients 8.8 to 20.8 years of age (mean, 15.5 years) with a history of wedge-shaped vertebral compression fracture at least 1 year previously (mean, 3.8 years) and asymptomatic healthy control subjects were studied by thoracolumbar spine magnetic resonance imaging. The patients also underwent a clinical examination. RESULTS: Eight (57%) of the 14 patients had disc degeneration, and seven of them had it at the trauma level. Of these 7 subjects, 6 also had endplate damage at this level. The association between endplate damage and adjacent intervertebral disc degeneration was significant (P < 0.01). Only 2 of the patients were symptomatic. In the control group, only 1 subject had disc degeneration with endplate changes and disc herniation.
CONCLUSIONS: The patients had more disc degeneration than did those in the control group. Endplate injury was strongly associated with disc degeneration. No correlation between previous vertebral fracture and back pain was seen in this study. _________________________________________________

Title: The use of an injectable, biodegradable calcium phosphate bone substitute for the prophylactic augmentation of osteoporotic vertebrae and the management of vertebral compression fractures.
Source: Spine. 24(15):1521-6, 1999 Aug 1.
Abstract: STUDY DESIGN: A biomechanical study comparing two materials for augmentation of osteoporotic vertebral bodies and vertebral bodies after compression fracture. OBJECTIVES: To compare an injected, biodegradable calcium phosphate bone substitute with injected polymethylmethacrylate bone cement for strengthening osteoporotic vertebral bodies and improving the integrity of vertebral compression fractures. SUMMARY OF BACKGROUND DATA: Injection of polymethylmethacrylate bone cement into fractured vertebral bodies has been used clinically. However, there is concern about thermal damage to the neural elements during polymerization of the polymethylmethacrylate bone cement as well as its negative effects on bone remodeling. Biodegradable calcium phosphate bone substitutes have been studied for enhancement of fixation in fractured vertebrae. METHODS: Forty fresh osteoporotic thoracolumbar vertebrae were used for two separate parts of this study: 1) injection into osteoporotic vertebrae: intact control (n = 8), calcium phosphate (n = 8), and polymethylmethacrylate bone cement (n = 8) groups. Each specimen then was loaded in anterior compression until failure; 2) injection into postfractured vertebrae: calcium phosphate (n = 8) and polymethylmethacrylate bone cement (n = 8) groups. Before and after injection, the specimens were radiographed in the lateral projection to determine changes in vertebral body height and then loaded to failure in anterior bending. RESULTS: For intact osteoporotic vertebrae, the average fracture strength was 527 +/- 43 N (stiffness, 84 +/- 11 N/mm), 1063 +/- 127 N (stiffness, 157 +/- 21 N/mm) for the group injected with calcium phosphate, and 1036 +/- 100 N (stiffness, 156 +/- 8 N/mm) for the group injected with polymethylmethacrylate bone cement. The fracture strength and stiffness in the calcium phosphate bone substitute group and those in the polymethylmethacrylate bone cement group were similar and significantly stronger than those in intact control group (P < 0.05). For the compression fracture study, anterior vertebral height was increased 58.5 +/- 4.6% in the group injected with calcium phosphate and 58.0 +/- 6.5% in the group injected with polymethylmethacrylate bone cement as compared with preinjection fracture heights. No significant difference between the two groups was found in anterior vertebral height, fracture strength, or stiffness. CONCLUSION: This study demonstrated that the injection of a biodegradable calcium phosphate bone substitute to strengthen osteoporotic vertebral bodies or improve vertebral compression fractures might provide an alternative to the use of polymethylmethacrylate bone cement. _______________________________________

Title: Adjacent vertebral failure after vertebroplasty. A biomechanical investigation.
Source: Journal of Bone & Joint Surgery - British Volume. 84(5):748-52, 2002 Jul.
Abstract: Vertebroplasty, which is the percutaneous injection of bone cement into vertebral bodies has recently been used to treat painful osteoporotic compression fractures. Early clinical results have been encouraging, but very little is known about the consequences of augmentation with cement for the adjacent, non-augmented level. We therefore measured the overall failure, strength and structural stiffness of paired osteoporotic two-vertebra functional spine units (FSUs). One FSU of each pair was augmented with polymethylmethacrylate bone cement in the caudal vertebra, while the other served as an untreated control. Compared with the controls, the ultimate failure load for FSUs treated by injection of cement was lower. The geometric mean treated/untreated ratio of failure load was 0.81, with 95% confidence limits from 0.70 to 0.92, (p < 0.01). There was no significant difference in overall FSU stiffness. For treated FSUs, there was a trend towards lower failure loads with increased filling with cement (r2 = 0.262, p = 0.13). The current practice of maximum filling with cement to restore the stiffness and strength of a vertebral body may provoke fractures in adjacent, non-augmented vertebrae. Further investigation is required to determine an optimal protocol for augmentation. __________________________________

Title: Enhanced osteoblast response to a polymethylmethacrylate-hydroxyapatite composite.
Source: Biomaterials. 23(1):133-44, 2002 Jan.
Abstract: Hydroxyapatite (HA)-reinforced polymers have been proposed as a method of improving the biological properties of bone cements and implant materials. For example, bone cements based on polymethylmethacrylate (PMMA) have long been used to secure orthopedic implants to the skeleton. This composite could also be used as a polished coating on other materials or in bulk form, shaped or molded, to custom fit a specific clinical need. However, complications may occur as a result of the limited mechanical and biological properties of PMMA. The purpose of this investigation was to determine whether the incorporation of HA in a PMMA matrix would enhance the biological properties of osteoblast response as compared to PMMA alone. Fetal rat calvarial osteoblasts were plated on discs of PMMA, PMMA/HA, commercially pure titanium (CpTi) and tissue culture polystyrene (control). Osteoblast attachment and day 2 proliferation were similar on all implant materials, whereas, day 8 proliferation on PMMA/HA was significantly higher than on PMMA and similar to CpTi and control. Extracellular matrix production was examined by immunohistochemistry which indicated that osteoblasts cultured on PMMA/HA showed a more distinct networked pattern of organized fibronectin. Histochemical staining of mineralization was examined by confocal microscopy which demonstrated a higher degree of mineralization in nodules formed on PMMA/HA as compared to PMMA. Together, these results indicate that the addition of HA in a PMMA matrix improves osteoblast response as compared to PMMA alone. Therefore, the incorporation of HA into a PMMA matrix may be a useful method to provide PMMA materials with enhanced osteogenic properties. _____________________________________________

Kyphoplasty
Kyphoplasty uses a two-step process of inserting of a special balloon device into the compacted vertebrae to attempt to restore the vertebrae to a more normal shape. Subsequently, a cement-like material (polymethylmethacrylate) is injected into the space created by the balloon to retain the correction. By restoring the vertebrae to a more normal state, alignment of the spine may be improved.
See: www.pcnt.org/kephoplasty.html
Kyphoplasty It is most beneficial when performed within two weeks to 6 months of the fracture,. Compared to conventional back surgeries that involve long incisions and lengthy hospital stays, Kyphoplasty is performed under local or general anesthesia through tiny incisions. A small tube is placed down to the fractured bone to create a path for a special balloon. Using x-ray, the orthopaedic surgeon carefully inflates the balloon to push up the fractured bone and restore the height of the fractured vertebra. The balloon is then deflated and the defects are filled with special bone cement. This instantly stabilizes the vertebra and gives pain relief.
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Title:: Low lumbar spinal fractures: management options.
Source:: Injury. 33(7):579-82, 2002 Sep. NLM Journal Code 0226040, gon

Fifty-four patients with low lumbar spinal fractures were retrospectively reviewed. Of these, there were 25 compression fractures, 21 burst fractures, three flexion-distraction fractures and five fracture-dislocations. Three patients had a complete neurological lesion, 17 sustained an incomplete neurological injury, and 34 were neurologically intact. Twenty-six patients were treated non-operatively and 28 underwent surgery. All patients were followed up for l-12 years. Forty-three patients (79.6%) have returned to their former employment or activity level. Four patients had experienced significant improvement but suffered from some limitation of activity. Five patients were unable to stand up and walk without support although they had some degree of improvement. Two remained completely paralyzed. There were no differences in neurologic function between patients treated non-operatively or operatively (P>0.05). The patients treated operatively had significantly less pain compared to the patients treated non-operatively (P<0.01). Because of the unique anatomy and biomechanics, fractures of the low lumbar spine are different from those in the remaining regions of spine. Most compression fractures are stable, and therefore conservative management is indicated. Surgery should be performed in those with burst fractures or flexion-distraction fractures, with severe spinal stenosis or kyphotic deformity, and fracture-dislocation. -----------------------------------

Title: An in vivo comparison of the potential for extravertebral cement leak after vertebroplasty and kyphoplasty.
Source: Spine. 27(19):2173-8; discussion 2178-9, 2002 Oct 1

CONCLUSIONS: The findings showed less vascular and transcortical extravasation of injected contrast with kyphoplasty than with vertebroplasty. Although leakage of contrast may not correlate precisely with polymethylmethacrylate leakage, the authors believe this study highlights the relative safety of these procedures. ________________________________________________

Title:: Late neurological deterioration 30 years following conservative treatment of a lower cervical spine fracture--a case report.
Source:: Zentralblatt fur Neurochirurgie. 63(2):77-80, 2002.

A today 44 years old man suffered from a compression and subluxation fracture of C 4 and C 5 vertebral body during a swimming accident in 1971. The primary therapy was conservative and the patient was rehabilitated. Since 1997 the patient showed a slowly progressive right hemiparesis with signs of cervical myelopathy. The diagnostic procedures revealed a severe deformity of the cervical spine with myelon compression. We performed an operation with replacement of C4 and C5 and dorsal stabilization at the same time. This very impressive case shows the risk of a late and slowly onset of myelopathic deterioration while latent bony instability persist post traumatic. The authors think in agreement with the actual literature that the early operative stabilization of instable fractures of the lower cervical spine is inevitable. According to the grade of neurological and bony damage the operation should not be performed later than 8-12 hours after injury. -----------------------------

Title: Evaluation of spinal curvatures after a recent osteoporotic vertebral fracture.
Source: Joint, Bone, Spine: Revue du Rhumatisme. 69(2):201-8, 2002 Mar.

CONCLUSION: Thoracic compression fractures significantly increase thoracic kyphosis as compared to dorsolumbar and lumbar fractures. Thoracic kyphosis worsens overtime in patients with prevalent vertebral fractures. These data invite an evaluation of techniques capable of providing early correction of alignment disorders, such as widespread use of bracing or kyphoplasty. ______________________________________________

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