Complications and problems related to pedicle screw fixation of the spine

This retrospective study analyzes the complications and the problems developed during and after pedicle screw fixation in patients with spinal disorders and trauma. One hundred twelve patients were treated using the Cotrel-Dubousset pedicle screw fixation system for degenerative disease (57 patients), trauma (42 patients), infection (eight patients), and tumor (five patients) of the lumbar or thoracolumbar spine. T e average age of the patients was 47 years and the average followup was 35 months. Forty-seven general complications were seen in 41 patients (36.5%). In addition, hardware failures were observed in 12 patients (10.7%), junctional problems were seen in five patients (4.5%), problems in the instrumented segments were seen in 39 patients (34.7%), and problems of balance occurred in five patients (4.5%). Although the rate of the reported complications was high, the final outcome of the patients was not affected significantly. Placement of the pedicle screws in the thoracolumbar and lumbar spine is a technically demanding procedure. It should be used by experienced and qualified surgeons who are aware of the pitfalls associated with its use

Mechanoreceptors of the posterior cruciate ligament

The mechanical role of the anterior and posterior cruciate ligaments in the passive and functional stability of the knee joint has been well documented. Both these knee joint ligaments contain Ruffini, Pacinian, Golgi and free nerve endings with different capabilities of providing the central nervous system with information regarding movement and position as well as chemical events. The posterior cruciate ligament provides 95% of the restraining force to a posterior tibial displacement, is significantly stronger than the other knee ligaments, and sensory nerve endings are located in the tibia and femoral bone insertions. This report aims to review the anatomy and physiology of the various mechanoreceptors of the posterior cruciate ligament, placing special emphasis on their role in knee joint stability. It concludes that the posterior crude ligament may not only serve as a ‘mechanical stabilizer’ of the knee joint, but also probably has an important ‘sensory function’ that should be taken into account when dealing with injuries to it

Gertzbein and load sharing classifications for unstable thoracolumbar fractures

From 1996 to 1998, 30 consecutive patients with Level I thoracolumbar spinal injury were classified and treated according to the Gertzbein classification and the load sharing classification. A posterior short segment pedicle screw implant was used in 21 patients; anterior decompression with strut grafting and application of the Kaneda device was used in three patients; and six patients were treated with short posterior instrumentation and an anterior strut graft. The average followup was 32 months (range, 24-50 months). The clinical outcome was satisfactory in 22 of 30 patients. Five of nine patients had neurologic improvement. Radiographic imaging findings showed a slight loss of reduction, but the clinical outcome of the patients was not affected. No pseudarthrosis and no implant failures were recorded. The Gertzbein classification correlates the type of fracture with the degree of mechanical instability and neurologic lesion. The load sharing classification correlates fracture comminution and displacement with mechanical stability and implant failure. Patient selection is a fundamental component for a successful outcome. The best candidates for surgery are cooperative patients who require spinal mobility, patients who are able to tolerate a two-stage reconstruction, and patients in good general health

Levels of bone collagen markers in preterm infants: Relation to antenatal glucocorticoid treatment

Although the beneficial effects of antenatally administered glucocorticoids are well documented, data on the potential of adverse consequences are limited. The objective of this study was to determine the effects of antenatally administered glucocorticoids on biochemical markers of bone metabolism of 55 preterm infants with a gestational age of 24-34 weeks who were enrolled in the study. Neonates were divided into two groups according to antenatal exposure to corticosteroids. There were no significant differences between the groups in clinical characteristics and anthropometric variables. We studied blood levels of osteocalcin (OC), carboxy-terminal propeptide of type I procollagen (PICP), and carboxy-terminal telopeptide of type I collagen (ICTP) at the time of delivery, on postnatal day 10, and at 2 and 4 months of life. Comparing the groups, we found statistically significant reduction in PICP levels at birth in corticosteroid-exposed neonates (P < 0.05). The levels of bone markers increased progressively on the first days of life. There were no significant differences between groups in bone markers at 10 days or at 2 and 4 months of life. We found no significant difference for bone markers between groups of infants exposed to single or repeated maternal corticosteroid treatments. In summary, antenatal glucocorticoid treatments are suggested to have a negative impact on fetal bone formation as reflected by low PICP levels at birth. However, this negative effect on bone markers seems to be a temporary effect that subsides on the first days of life and afterward. © 2007 Springer-Verlag

Quantitative ultrasound measurements in premature infants at 1 year of age: The effects of antenatal administered corticosteroids

The aim of this study was to evaluate the effects of antenatally administered glucocorticoids on bone status of preterm infants at 1 year corrected age. The study population consisted of 32 preterm infants with a gestational age of 24-34 weeks. The infants were divided into two groups according to antenatal exposure to corticosteroids. Quantitative ultrasound (QUS) assessment of bone was performed in the study infants at the corrected age of 1 year. Blood levels of carboxy-terminal propeptide of type I procollagen (PICP) and carboxy-terminal telopeptide of type I collagen (ICTP) were measured at birth and at 1 year corrected age. Levels of PICP and ICTP were significantly lower at birth in corticosteroid-exposed neonates (P < 0.05). At corrected age of 12 months ICTP levels remained significantly lower in corticosteroid-exposed infants, but we found no significant difference in levels of the bone-formation marker PICP between corticosteroid-exposed and nonexposed infants. In the majority of participant preterm infants bone speed of sound (SOS) was within age-adjusted normal values of full-term infants. There was no significant difference in bone SOS between exposed and nonexposed infants at corrected age of 12 months. There was no correlation between SOS and levels of bone markers. The results of our study indicate that, despite the suppression of fetal bone turnover at birth in corticosteroid-exposed infants, antenatal glucocorticoid treatment seems to have no long-term impact on bone status of preterm infants assessed by QUS complementary to measurement of bone-turnover markers at 1 year corrected age. © 2010 Springer Science+Business Media, LLC

Classificação de McCormack e colapso sagital na fratura toracolombar explosão McCormack classification and kyphotic deformity in thoracolumbar burst fractures

O aumento da cifose toracolombar após tratamento conservador da fratura tipo explosão é complicação constatada por vários autores. Realizamos estudo retrospectivo com 33 portadores de fratura toracolombar do tipo explosão submetidos ao tratamento conservador entre 1992 a 2004 para verificar a correlação entre a cifose toracolombar e a Classificação de McCormack, que pontua a gravidade da fratura conforme a cominuição do corpo, o deslocamento dos fragmentos no corpo vertebral e a quantidade de correção da deformidade em cifose após o tratamento. Após 30 meses de seguimento médio, verificamos correlação entre a pontuação da Classificação de McCormack, conhecida na literatura como load sharing classification, e o colapso vertebral sagital nestes pacientes (p<0,05;r=0,65). A despeito de ser descrita para avaliação do colapso sagital após o tratamento cirúrgico, a aplicabilidade desta Classificação pode ser considerada para os portadores de fratura toracolombar explosão submetidos ao tratamento conservador.<br>The increasing incidence of thoracolumbar kyphosis after conservative treatment of burst fractures is a complication reported by several authors. We performed a retrospective study on a consecutive series of 33 patients with thoracolumbar burst fractures treated with cast or brace immobilization between 1992 and 2004 to check for a correlation between thoracolumbar kyphosis and Load Sharing Classification, which provides fracture severity scores according to body comminution, vertebral body fragments displacement and the amount of kyphosis correction delivered after treatment. After an average of 30 months of follow-up we found a correlation between Load Sharing Classification scores (also known as McCormack's Classification), and the sagittal kyphotic deformity on these patients (p<0.05;r=0.65). Despite of being described for assessing sagittal deformity after surgical treatment, the applicability of this Classification can be considered for patients with thoracolumbar burst fractures submitted to conservative treatment

Does the load-sharing classification predict ligamentous injury, neurological injury, and the need for surgery in patients with thoracolumbar burst fractures?

Object. The load-sharing score (LSS) of vertebral body comminution is predictive of results after short-segment posterior instrumentation of thoracolumbar burst fractures. Some authors have posited that an LSS > 6 is predictive of neurological injury, ligamentous injury, and the need for surgical intervention. However, the authors of the present study hypothesized that the LSS does not predict ligamentous or neurological injury. Methods. The prospectively collected spinal cord injury database from a single institution was queried for thoracolumbar burst fractures. Study inclusion criteria were acute (<24 hours) burst fractures between T-10 and L-2 with preoperative CT and MRI. Flexion-distraction injuries and pathological fractures were excluded. Four experienced spine surgeons determined the LSS and posterior ligamentous complex (PLC) integrity. Neurological status was assessed from a review of the medical records. Results. Forty-four patients were included in the study. There were 4 patients for whom all observers assigned an LSS > 6, recommending operative treatment. Eleven patients had LSSs 6. Correlations between the LSS and the PLC score averaged 0.18 across all observers (range -0.02 to 0.34, p value range 0.02-0.89). Correlations between the LSS and the American Spinal Injury Association motor score averaged -0.12 across all observers (range -0.25 to -0.03, p value range 0.1-0.87). Correlations describing the relationship between an LSS > 6 and the treating physician's decision to operate averaged 0.17 across all observers (range 0.11-0.24, p value range 0.12-0.47). Conclusions. The LSS does not uniformly correlate with the PLC injury, neurological status, or empirical clinical decision making. The LSSs of only one observer correlated significantly with PLC injury. There were no significant correlations between the LSS as determined by any observer and neurological status or clinical decision making. (http://thejns.org/doi/abs/10.3171/2012.3.SPINE11570