Estudo morfométrico do pedículo das vértebras lombares Morphometric study of lumbar vertebrae's pedicle

Foi realizado estudo morfométrico de dez segmentos de coluna lombar de cadáveres adultos de ambos os sexo com a finalidade de estudar parâmetros relacionados com a morfometria dos pedículos da coluna lombar. Os pedículos foram seccionados transversalmente de ambos os lados na altura do seu menor diâmetro. As vértebras foram fotografadas e o estudo morfométrico foi realizado em aparelho Minimop, tendo sido avaliados bilateralmente: o formato do pedículo, o diâmetro, a espessura das paredes corticais, a área do pedículo, a área do osso cortical, a área de osso esponjoso, e a porcentagem de osso esponjoso e cortical do pedículo. O pedículo vertebral da coluna lombar apresenta forma oval, o diâmetro vertical é maior que o horizontal, a cortical medial é mais espessa, a área do pedículo aumenta no sentido crânio cauda, e a relação entre a área de osso cortical e esponjoso é constante em toda a extensão da coluna lombar.<br>A morphometric study was performed on ten lumbar spine fragments from adult cadavers of both genders in order to study parameters related to lumbar spine pedicles' morphometry. The pedicles were cross-sectioned on both sides at the level of their smallest diameter. Vertebrae were photographed and the morphometric study was conducted using a Minimop instrument. The following parameters were bilaterally assessed: pedicle shape and diameter, cortical walls thickness, pedicle area, cortical bone area, spongy bone area, and percentage of spongy and cortical bone of the pedicle. The vertebral pedicle of the lumbar spine has an oval shape, its vertical diameter is larger than its horizontal diameter, the medial cortical bone wall is thicker, the area of the pedicle increases towards skull-tail, and the cortical and spongy bone areas ratio is constant throughout the extension of the lumbar spine

Low thoracic and lumbar burst fractures: radiographic and functional outcomes

Twenty patients with thoracolumbar burst fractures (type A3 in the classification of Magerl et al.) were studied prospectively for the evaluation of clinical, radiographic and functional results. The patients were submitted to surgical treatment by posterior arthrodesis, posterior fixation and autologous transpedicular graft. The patients were followed up for 2 years after surgery and assessed on the basis of clinical (pain, neurologic deficit, postoperative infection), radiographic (load sharing classification, Farcy´s sagittal index of the fractured segment, relation between traumatic vertebral body height and the adjacent vertebrae (compression percentage), height of the intervertebral disk proximal and distal to the fractured vertebra, rupture or loosening of the implants) and functional (return to work, SF-36) criteria. Two patients presented a marked loss of correction and required the placement of an anterior support graft. Pain assessment revealed that eight patients (44%) had no pain; four (22%) had occasional pain, three (17%) moderate pain, and three (17%) severe pain. According to the classification of Frankel et al., 17 patients persisted as Frankel E and one patient presented improvement of one degree, becoming Frankel D. The mean value of Farcy´s sagittal index of the injured vertebral segment was 20.67° ± 6.15° (range 8°–32°) during the preoperative period, 11.22° ± 8.09° (range −5° to 21°) during the immediate postoperative period, and 14.22° ± 7.37° (range 3°–25°) at late evaluation. There was a statistically significant difference between the immediate postoperative values and the preoperative and late postoperative values. The compression percentage of the fractured vertebral body ranged from 9.1 to 60 (mean 28.81 ± 11.51) during the preoperative period, from 0 to 60 (mean: 15.59 ± 14.49) during the immediate postoperative period, and from 8 to 60 (mean: 25.9 ± 13.02) at late evaluation. There was a statistically significant difference between the preoperative and postoperative values and between the postoperative and late postoperative values. The height of the proximal intervertebral disk ranged from 6 to 14 mm (mean 8.44 ± 2.66) during the preoperative period, from 6 to 15 mm (mean 10 ± 2.30) during the immediate postoperative period, and from 0 to 11 mm (mean 7.22 ± 2.55) during the late postoperative period. A significant difference was observed between the immediate postoperative values and the preoperative and late postoperative values. The height of the intervertebral disk distal to the fractured vertebra ranged from 7 to 16 mm (mean 9.94 ± 2.64) during the preoperative period, from 5 to 18 mm (mean 11.61 ± 3.29) during the immediate postoperative period, and from 2 to 14 mm (mean 9.72 ± 3.17) during the late postoperative period. There was a significant difference between the immediate postoperative values and the preoperative and late postoperative values. Except for the height of the intervertebral disk proximal to the fractured vertebra, no correlation was detected between the clinical, functional and radiologic results. The results observed in the present study indicate that other, still incompletely defined parameters influence the functional result of thoracolumbar burst fractures

Influência do local de ancoragem dos implantes na vértebra sobre o torque de inserção e resistência ao arrancamento Influencia de la ubicación de los implantes en la vértebra cuanto al torque de inserción y resistencia de arrancamiento Influence of anatomical vertebral site on screw insertion torque and pull-out strength

OBJETIVO: Avaliar a influência do sítio anatômico da ancoragem dos implantes na vértebra sobre a resistência ao arrancamento e o torque de inserção dos parafusos pediculares com alma cônica e cilíndrica. MÉTODOS: Parafusos cilíndricos e com alma cônica foram inseridos no pedículo e corpo vertebral de 10 vértebras lombares (L4-L5) de vitelos. Foram avaliados o torque de inserção e a resistência ao arrancamento dos parafusos inseridos no corpo e no pedículo vertebral. RESULTADOS: Os valores do torque de inserção e resistência ao arrancamento foram maiores nos parafusos de alma cilíndrica e alma cônica inseridos no pedículo vertebral. CONCLUSÕES: A ancoragem dos implantes no pedículo vertebral apresentou maiores valores do torque de inserção e da força de arrancamento que os implantes inseridos no corpo vertebral nos dois tipos de parafusos utilizados.<br>OBJETIVO: Evaluar la influencia de la localización anatómica de la fijación de los implantes en la vértebra cuanto al torque de inserción y resistencia de arrancamiento de los tornillos con alma cónica y cilíndrica. MÉTODOS: Los tornillos con alma cilíndrica y cónica se insertan en el cuerpo y el pedículo vertebral de diez vértebras lumbares (L4-L5) de los terneros. Se evaluó el torque de inserción y resistencia al arrancamiento de tornillos insertados en el cuerpo y el pedículo. RESULTADOS: El torque de inserción y resistencia al arrancamiento fue mayor para los tornillos con alma cónica y cilíndrica insertados en el pedículo. CONCLUSIONES: La fijación de los implantes en el pedículo mostró mayor torque de inserción y resistencia al arrancamiento en comparación con los implantes en el cuerpo vertebral, en ambos tipos de tornillos.<br>OBJECTIVE: To evaluate the influence of anatomical site of implants on vertebra about insertion torque and pull-out strength of conical and cylindrical core screws. METHODS: Conical and cylindrical core screws were inserted into the pedicle and vertebral body of 10 lumbar vertebrae (L4-L5) of calves. In the study were evaluated insertion torque and pull-out strength of screws inserted into the body and pedicle. RESULTS: The insertion torque and pull-out strength were higher for conical and cylindrical core screws inserted into vertebral pedicle. CONCLUSIONS: The anchoring of implants into the pedicle showed higher insertion torque and pull-out strength than implants inserted into the vertebral body in both types of screws used