Anterior transpedicular fixation of the lower thoracic and lumbar spine. Experimental verification using a new direction finder

Currently, no anterior spinal implant provides a strong bone-screw interface because of the cancellous characteristics of the vertebral body. A more secure anchorage could be obtained by anterior transpedicular screw fixation. Four hundred transpedicular screws located between T7 and L5 were placed using the newly developed direction finder. Measurements were obtained directly from radiographs of the cadaveric specimens. In 10 cases (2.5%), the screws crossed the medial pedicle border, but never by more than 1.4 mm. A lateral protrusion was noted in another 41 screws (10%), with no protrusion greater than 2.2 mm. Encroachments beyond the superior or inferior border were not observed. The mean angle of the screws at each level measured between 7 and 19 in the transverse plane and between 2 and 4.5 in the sagittal plane. This technique should be reserved for vertebrae without significant arthritic changes. The rare screw with minimal infraction through the medial or lateral pedicle wall should not cause any vascular or neural compromise. The anterior transpedicular screw technique appeared relatively safe (88%) and encouraged the development of the new plate system for anterior spinal stabilization.     

Harrington instrumentation in fractures and dislocations of the thoracic and lumbar spine

Harrington instrumentation was used to treat 23 injuries of the thoracic and lumbar spine accompanied by neural damage encountered during an 8 1/2-year period. The indication for the use of Harrington instrumentation is instability of the thoracic or lumbar spine due to trauma, laminectomy, or both. Of the 13 patients with incomplete neural lesions in the series, 12 improved. One of these was a cauda equina lesion. No patient in the series was neurologically worse after operation, in contrast to other reported series in which laminectomy alone was done. It is concluded that Harrington instrumentation is the strongest available system of internal fixation, and the only one that permits reduction of nearly all traumatic spinal deformities at the time of operation.     

Ultra-low magnetic resonance tomography of thoracic and lumbar spine osteochondrosis

The paper presents the results of tomographic studies of 119 patients with clinical manifestations of radiculopathy or radiculomyelopathy. MR tomography was performed on the Magnaview unit ("Instrumentarium", Finland) at field intensity 0.04 T. The analysis of T1- and T2-weighted sagittal tomograms providing MRT picture of osteochondrosis and various hernias shows that osteochondrosis involves several disks simultaneously while their bulging towards the vertebral canal is multiple. The severity of the hernia in some cases does not closely agree with degeneration degree or the decline of the vertebral disk height. However there is a close correlation between the size and direction of the hernia on the one hand and the clinical manifestations on the other hand.     

Surgical management of dumbbell and paraspinal tumors of the thoracic and lumbar spine

The lateral extracavitary approach was used for single-staged tumor resection in 12 patients with complex dumbbell or paraspinal tumors of the thoracic and lumbar spine. Six women and six men (age, 28-72 yr) were treated between August 1990 and January 1994. The tumors included schwannoma (6 patients), malignant meningioma (1 patient), hemangioma (1 patient), chondrosarcoma (1 patient), osteocartilaginous exostosis (1 patient), radiation-induced osteogenic sarcoma (1 patient), and metastatic renal carcinoma (1 patient). Gross total resection was achieved in 11 patients. Radical subtotal removal was performed in the remaining patient, who had a malignant osteogenic sarcoma. Concomitant spinal stabilization with internal fixation and anterior interbody strut grafting was performed on two patients. No significant perioperative complications occurred. Ten patients were alive and clinically stable at follow-up visits ranging from 14 to 55 months. Two patients died from systemic tumor dissemination during the follow-up period. The lateral extracavitary approach is useful when extensive or difficult spinal and paraspinal exposure is required. The surgical aspects of these neoplasms and the technique of lateral extracavitary approach are described in detail.     

Transmural pressure of epidural veins in the thoracic and lumbar spine of pigs

We recently cloned a new leukemogenesis-associated gene MmTRA1a (Mm-1 cell derived transplantability-associated gene 1a, former name "TRA1") from a mouse leukemogenic and monocytic Mm-P cell cDNA library and also cloned its normal counterpart MmTRA1b (former name "NOR1") from a normal mouse kidney cDNA library. The mouse MmTRA1a is a truncated form of mouse MmTRA1b. Here we report the cloning of a cDNA (human MmTRA1b) homologous to the mouse MmTRA1b from a human monocytic U937 cell cDNA library. The human MmTRA1b cDNA predicts a peptide containing 318 amino acids with a calculated molecular weight of 35,047 Da. The predicted human MmTRA1b protein sequence shared 78% amino acid identity with the mouse counterpart (328 amino acids). Both the human homologue and mouse MmTRA1b protein but not MmTRA1a protein possess a proline-rich domain at the N-terminal end. The human MmTRA1b gene was mapped to chromosome 3q23. Expression of the human homologue was increased during differentiation of U937 cells induced by most typical differentiation inducers. Moreover, predicted amino acid sequence analysis of human MmTRA1b cDNA revealed perfect identity with the human plasma membrane phospholipid scramblase that is required for transbilayer movement of membrane phospholipids. These results provide new information on the possible roles of MmTRA1b/phospholipid scramblase and the truncated MmTRA1a in the leukemogenesis and differentiation of monocytic leukemia cells.     

Surgical treatment of deformities of the thoracic and lumbar spine by posterior spinal osteotomy

From 1987 to 1993, we performed spinal osteotomy with posterior closing-wedge using a single-operation technique in 20 patients with kyphosis. Spinal deformity resulted from mal union after spinal injury in 13 patients and from ankylosing spondylarthritis in 7. Mean duration of the procedure was 4 h 15 min (range 2 h 30 min to 7 h) for mal union and 3 hours (2 h 30 to 4 h) for ankylosing spondylarthritis. Intraoperative blood loss was estimated at 1.8 liters (0.5-4) and 1 liter (0.5-1.5) respectively. Osteotomy was performed at L3 in all cases of spondylarthritis with a mean 30 degrees correction (24-37 degrees) which was maintained after 5 to 18 months follow-up (mean 10 months). For mal union, the mean angular correction was better and more stable after 3 to 84 months (mean 23 months) for the thoracic or thoraco-lumbar segments than for the lumbar spine. Functional results were excellent or good for 11 patients, acceptable for 1 and poor for 1. Three patients with recurrent radiculalgia with mal union were cured after the operation while the neurological status of the paraplegic patients remained unchanged. There were no fatal complications nor neurological or vascular complications among the 20 patients. There were 4 complications in patients with an abnormal callus including 3 mechanical complications and one deep infection. For spondylarthritis, there were no complications at maximum follow-up.     

Carbonated apatite cement augmentation of pedicle screw fixation in the lumbar spine

STUDY DESIGN: Biomechanical testing with human cadaveric lumbar vertebral bodies was used to determine the utility of an injectable carbonated apatite cancellous bone cement for improving the structural performance of pedicle screws subjected to axial pull-out or transverse cyclic loading. OBJECTIVES: To ascertain whether augmentation with a carbonated apatite cement can enhance pedicle screw fixation in the lumbar spine. SUMMARY OF BACKGROUND DATA: The beneficial effects of polymethylmethacrylate augmentation on pedicle screw pull-out strength have been demonstrated. Cancellous bone cement, however, may provide an attractive alternative in this application, as it is remodelable, biocompatible, and nonexothermic. METHODS: Forty-three cadaveric lumbar vertebral bodies were instrumented with pedicle screws. In 20 of these specimens, axial pull-out strength was compared between the control screws and those augmented with cancellous bone cement. In the remaining 23 specimens, the screws were loaded in the superior-inferior direction with a peak displacement of +/- 1 mm at a frequency of 3 Hz for 5000 cycles. Three parameters were calculated from the force-versus-time data: 1) the energy dissipated, 2) the peak force at the start of the test, and 3) the peak force at the end of 5000 cycles. RESULTS: The pull-out strength of the augmented pedicles averaged 68% greater than that of the control side. In response to cyclic loading, all measures of bio-mechanical performance improved 30-63%. CONCLUSIONS: The data suggest that augmentation with this carbonated apatite cancellous bone cement can enhance immediate screw fixation.     

Percutaneous biopsy of the thoracic and lumbar spine: transpedicular approach under fluoroscopic guidance

BACKGROUND: Merkel cell carcinoma (MCC) is a rare, aggressive, cutaneous neoplasm. The primary form of initial treatment is wide surgical excision. The use of Mohs micrographic surgery as the primary form of treatment in MCC has been controversial. The course of MCC is often aggressive, with early metastasis, widespread disease, and death. Despite the poor prognosis, spontaneous regression has occasionally been reported. OBJECTIVE: We describe the clinical course of two patients with Merkel cell carcinoma who underwent treatment with Mohs micrographic surgery for the primary MCC. Metastases were excised in the first case and spontaneously regressed in the second. Both patients are without clinical disease at the time of this report. METHODS: Histopathology, clinical records, and the current literature are reviewed. RESULTS: One patients was without recurrence of MCC for 13 years of follow-up. The other patient experienced clinical spontaneous remission after nodal spread of the disease, with no recurrence for 18 months after clinical remission and 24 months after surgery. CONCLUSION: The treatment of Merkel cell carcinoma with Mohs micrographic surgery (MMS) has been successful for the control of primary skin disease, and is at least comparable to wide excision. Spontaneous regression may occur in the course of this usually relentless and aggressive disease. The explanation for spontaneous regression of MCC is unknown.     

Translaminar screw fixation of the lumbar and lumbosacral spine. A 5-year follow-up

STUDY DESIGN: In a retrospective study, the long-term results of translaminar facet screw fixation of the lumbar and lumbosacral spine are reviewed. OBJECTIVES: To evaluate the clinical results, fusion rates and complications of this posterior fusion technique in various conditions of the lumbar spine. SUMMARY OF BACKGROUND DATA: Posterior fusion of the lumbar and lumbosacral spine is one of the possible methods to relieve pain and eliminate instability in degenerative conditions. Data in the literature support the use of internal fixation to optimize the rate of fusion. METHODS: Posterior lumbar and lumbosacral fixation with translaminar screws and fusion in 173 patients with degenerative changes with or without compressive syndromes including failed back syndromes, monosegmental hypermobilities, and posttraumatic conditions were investigated. Fixation and fusion with translaminar screws was performed in 57% monosegmentally, in 40% across two segments and in 2% over three segments. Decompressive surgery was performed in addition in 52% and nucleotomy in 30% of the cases. Clinical and radiologic assessment with flexion/extension x-rays was performed in 145 (83%) patients by two independent orthopedic surgeons. After an average follow-up of 68 months (range, 52-83). RESULTS: Ninety-four percent of the patients showed solid bony fusion in the radiologic follow-up. Loosening of the screws was noted in 3%, and two screws were broken without apparent motion on the functional x-rays. Pain scores decreased from 7.6 before surgery to 2.9 after surgery on a 10-point pain scale. The results were further analyzed according to Stauffer and Coventry with 99 good results, 70 satisfactory results, and 4 bad results. CONCLUSIONS: Translaminar screw fixation offers an immediate postoperative stability of the lumbar and lumbosacral spine and enhances fusion. In the present series no neurologic complications were noted. It represents a useful and inexpensive technique for short segment fusion of the nontraumatic lumbar and lumbosacral spine.     

Transpedicular stabilization in spinal and vertebral column injuries in thoracic and lumbar spine segments

The authors present their own experience in application of transpedicular internal stabilization of the thoracic and lumbar spine. Clinical analysis was carried out in a group of 12 patients after vertebral column and spinal trauma managed surgically in the Department of Neurosurgery in Poznań between 1.06.95 and 31.12.96. Age of patients ranged from 19 to 56 years (mean age 35.08 +/- 13.04 yrs.). The level of vertebral fracture was as follows: thoracic (2 cases), thoraco-lumbar (6 cases) and lumbar (4 cases). Three patients were completely paraplegic. All patients underwent posterior or posterolateral surgical approach. The fractured parts of bones, translocated into vertebral canal were removed and nervous structures were decompressed. Transpendicular stabilization was performed after the decompression. Improvement of neurological condition was observed in 8 patients.     

Mechanics of the external fixation test in the lumbar spine. A roentgen stereophotogrammetric analysis

The subjects of this study were 48 asymptomatic patients who had surgery for small hepatocellar carcinoma (HCC). There were 42 men and six women with mean (s.d.) tumour size of 3.31 (1.46) cm and age 55.0 (7.4) years. Follow-up was for a minimum of 10 years. The main concern of this study was a univariate analysis of factors that might affect long-term survival after surgery, which was 50 per cent at 5 years and 31 per cent at 10 years. A high incidence of recurrent HCC (37 of 48 patients) was observed but reoperation further prolonged life in some cases. The significant prognostic factors detected by multivariate analysis were: histological classification, functional liver reserve and histology of the resection margin. Tumour size, gross appearance of tumour, presence of liver cirrhosis, serum alpha-fetoprotein level, age or sex did not affect the prognosis.     

Myelolipoma of the thoracic spine

We describe a myelolipoma of the thoracic spine in a patient with gradual and progressive myelopathy. MR imaging showed this predominately fatty lesion to be extradural in location.     

Anatomy of the lumbar spine

The macroscopic courses of the posterior primary rami in the lumbar spine are described and illustrated from fresh cadaver dissections.     

Internal fixation of the spine in traumatic and scoliotic cases. The potential of pedicle screws

Internal fixation techniques are in common used to stabilize vertebral fractures and correct severe scoliosis. Consolidation of injured vertebrae with neighbouring intact vertebra is the goal in the former case whilst fusion of the vertebrae in a corrected position is aimed at in the latter case. Degenerative spine diseases are not considered in this paper. Classical instrumentation consists of rods (e.g., Cotrel-Dubousset, Harrington, Luque-Galveston) attached to the bone by means of hooks or wires. More recently, transpedicular screws are introduced as an alternative bone/implant interface. Comparing the results of several studies, the posterior pedicle screw based devices demonstrate the ability to produce the most rigid constructs. However, the insertion of pedicle screws implicates a relatively high complication risk and its success strongly depends on the experience of the surgeon. Incorrect drilled holes or malplacement of the screws can result in nerve root injuries and fracture of the pedicle. Studies reported complication ratios up to 30% with substantial neurological implications. A certain degree of automation of the critical actions may be necessary to enhance the safety of pedicle screw insertion. Two techniques of computer assisted spine surgery are compared. Both techniques permit a computer assisted surgical planning based on CT images. During operation the first system permanently observes the position of the drill relative to the spine and informs the surgeon on the deviation of the actual drill path to the planned drill path. The second system uses a pre-operative surgical planning to design and construct a mechanical drill guide, fitting perfectly on the patient's spine.     

Osteoplastic fixation of the spine

The combined anterolateral osteoplastic fixation of the spine was carried out on 17 cases out of 73 operated upon for pathological spinal changes of various etiology. The tibial crest rigid homograft and the rib autograft on vasoneuromuscular feeding pedicle were used. Such a combination of bone grafts possessing different mechanic and osteogenic properties permitted to obtain a reliable fixation of the spine for all the period necessary for anatomic and functional reconstruction of the grafts.     

Percutaneous biopsy of the thoracic spine

The aspartate aminotransferase gene (AspAT, EC 2.6.1.1) of an extremely thermophilic bacterium, Thermus thermophilus HB8, was cloned and sequenced, and its gene product was overproduced. The purified T. thermophilus AspAT was stable up to about 80 degrees C at neutral pH. T. thermophilus AspAT was strictly specific for acidic amino acid substrates, such as aspartate, glutamate, and the respective keto acids. The gene coding for T. thermophilus AspAT showed that it comprised 1,155 bp with a high G+C content (70 mol%), and encoded a 385-residue protein with a molecular weight of 42,050. The amino acid sequence of T. thermophilus AspAT deduced from its gene showed about 15, 46, and 29% homology with those from Escherichia coli, Bacillus sp. YM-2, and Sulfolobus solfataricus, respectively. When the amino acid sequence of T. thermophilus AspAT was compared with that of E. coli AspAT, the number of Cys was found to have decreased from 5 to 1, that of Asn from 23 to 9, that of Gln from 16 to 8, and that of Asp from 20 to 13, all of which are known to be relatively labile at high temperatures. Conversely, the number of Pro was increased from 15 to 25, Arg from 22 to 32, and Glu 27 to 37. As shown by the E. coli AspAT structure, there was a marked tendency for the extra prolyl residues to be located around the surface of the molecule. This was quite different from that in the case of RecA protein, which shows an increased number of prolyl residues in the interior of its molecule. Different strategies of different proteins as to prolyl contribution to thermostability have been suggested. Despite the high degree of conservation of active-site residues, Arg292 in E. coli AspAT, which interacts with the distal carboxylate of the substrate, was not found in T. thermophilus AspAT. Arg89 may complement the function of Arg292.     

Physical measurements of the lumbar spine

This article describes measurement of lumbar function. The simplest range of motion devices are compared with the progressive, more complex computerized devices for range and strength testing. The author presents his own opinion as to the place of these devices in both research and clinical practices. The economics of accurate physical testing is compared to the clinical realities of current payment systems.     

Kinematics of the pelvic girdle and the thoracic and lumbar segments in the course of the lateral inclinations and rotations of the spine

Physiological displacements of the trunk are the addition of these of the pelvic girdle and thoracic and lumbar spine segments. For a long time (3), this conjunction had been noticed but without numbered precisions. The purpose of this communication is to appreciate quantitatively, from a series of 16 subjects, the respective share of each components during lateral bending movements in the frontal plan and movements of rotation in the transverse plan. It results from this work that the pelvic girdle presents as reduced amplitude (4 degrees) in lateral bending on the other hand, displacement predominate to the level of thoracic spine (50 degrees). In rotation pelvic displacements are very important (30 degrees), while the spine so thoracic that lumbar has a weak participation (inferior to 5 degrees). Moderated abduction of hips increases by significant manner the motility of the pelvic girdle.