vendex and Spinal-Diseases

We investigated the effects of hydroxyapatite (HA) coating on the purchase of pedicle screws. A total of 23 consecutive patients undergoing lumbar fusion was randomly assigned to one of three treatment groups. The first received uncoated stainless-steel screws, the second screws which were partly coated with HA, and the third screws which were fully coated. The insertion torque was recorded. After 11 to 16 months, 21 screws had been extracted. The extraction torque was recorded. Radiographs were taken to assess fusion and to detect loosening of the screws. At removal, the extraction torques exceeded the upper limit of the torque wrench (600 Ncm) for many HA-coated screws. The calculated mean extraction torque was 29 +/- 36 Ncm for the uncoated group, 447 +/- 114 Ncm for the partly-coated group and 574 +/- 52 Ncm for the fully-coated group. There were significant differences between all three groups (p < 0.001). There were more radiolucent zones surrounding the uncoated screws than the HA-coated screws (p < 0.001). HA coating of pedicle screws resulted in improved fixation with reduced risk of loosening of the screws.

Topics: Adult; Aged; Bone Screws; Coated Materials, Biocompatible; Durapatite; Female; Humans; Lumbar Vertebrae; Male; Middle Aged; Prospective Studies; Radiography; Spinal Diseases; Spinal Fusion; Stainless Steel; Torque

The aim of the study was to determine the effect of comorbidities on physical function and quality of life of patients at 3 mos after total knee arthroplasty.. Data from 140 patients who underwent a primary unilateral total knee arthroplasty were examined retrospectively. Comorbidities were osteoporosis, presarcopenia, degenerative spine disease, diabetes, and hypertension. All patients completed the following: range of motion, stair climbing test, 6-min walk test, Timed Up and Go Test, peak torque of the knee extensor and flexor, instrumental gait analysis, Western Ontario McMaster Universities Osteoarthritis Index, and EuroQoL five-dimension questionnaire.. Univariate analyses revealed that osteoporosis led to a significantly longer time to complete the stair climbing test-ascent, stair climbing test-descent, and Timed Up and Go Test and to lower scores for the 6-min walk test and peak torque of the knee extensor. Patients with degenerative spine disease showed significant negative scores for knee extension range of motion. Diabetes showed a negative correlation with peak torque of the knee extensor and knee flexion range of motion, as well as a higher Western Ontario McMaster Universities Osteoarthritis Index-stiffness score. Multivariable linear regression analysis showed that Western Ontario McMaster Universities Osteoarthritis Index-stiffness remained independently associated with diabetes. Six-minute walk test, Timed Up and Go Test, stair climbing test-ascent, and peak torque of the knee extensors showed a significant association with osteoporosis.. Comorbidities, particularly osteoporosis and diabetes, affect short-term functional outcomes 3 mos after total knee arthroplasty.

Topics: Aged; Arthroplasty, Replacement, Knee; Comorbidity; Diabetes Mellitus; Disability Evaluation; Female; Gait Analysis; Humans; Hypertension; Knee Joint; Linear Models; Male; Osteoarthritis, Knee; Osteoporosis; Postoperative Period; Quality of Life; Range of Motion, Articular; Recovery of Function; Retrospective Studies; Sarcopenia; Spinal Diseases; Stair Climbing; Time and Motion Studies; Torque; Treatment Outcome; Walk Test

In vivo analysis of insertional torque of pedicle screws using cortical bone trajectory (CBT) technique.. To investigate factors contributing to the fixation strength of CBT screws and to clarify the ideal cortical trajectory for lumbar fusion.. CBT has developed as a new minimally invasive technique of lumbar instrumentation. Despite biomechanical studies demonstrating the superior characteristics of CBT, no study has elucidated the most suitable path for optimal fixation or compared the fixation within variations of trajectory.. The insertional torque of pedicle screws using CBT was measured intraoperatively in 72 consecutive patients. The detailed positions of a total of 268 screws were confirmed using postoperative reconstruction computed tomographic scans and were analyzed to identify factors contributing to the level of insertional torque. Investigated factors were as follows: (1) age, (2) bone mineral density of the femoral neck and lumbar vertebrae by dual-energy x-ray absorptiometry; (3) the pedicle width and height, (4) the length of the implant, (5) total screw length within the vertebra, (6) the screw length within the vertebral body, (7) the screw length within the lamina, (8) the cephalad and lateral angle of the trajectory, and (9) the distance from the long axis of the screw to the inferior and medial borders of the pedicle.. Multiple regression analysis showed that bone mineral density of the femoral neck, screw length within the lamina, and cephalad angle were significant independent factors affecting torque.. The fixation of CBT screws varied depending on technical factors (cephalad angle and screw length within the lamina) as well as the individual patient factor of bone mineral density. The ideal trajectory was directed 25° to 30° cranially along the inferior border of the pedicle so as to obtain maximum contact with the lamina and sufficient length within the vertebral body.. 2.

Topics: Adult; Aged; Aged, 80 and over; Bone Density; Bone Screws; Female; Humans; Lumbar Vertebrae; Male; Middle Aged; Prosthesis Implantation; Spinal Diseases; Spinal Fusion; Tomography, X-Ray Computed; Torque; Young Adult

The insertional torque of pedicle screws using the cortical bone trajectory (CBT) was measured in vivo.. To investigate the effectiveness of the CBT technique by measurement of the insertional torque.. The CBT follows a mediolateral and caudocephalad directed path, engaging with cortical bone maximally from the pedicle to the vertebral body. Some biomechanical studies have demonstrated favorable characteristics of the CBT technique in cadaveric lumbar spine. However, no in vivo study has been reported on the mechanical behavior of this new trajectory.. The insertional torque of pedicle screws using CBT and traditional techniques were measured intraoperatively in 48 consecutive patients. A total of 162 screws using the CBT technique and 36 screws using the traditional technique were compared. In 8 of 48 patients, the side-by-side comparison of 2 different insertional techniques for each vertebra were performed, which formed the H group. In addition, the insertional torque was correlated with bone mineral density.. The mean maximum insertional torque of CBT screws and traditional screws were 2.49 ± 0.99 Nm and 1.24 ± 0.54 Nm, respectively. The CBT screws showed 2.01 times higher torque and the difference was significant between the 2 techniques (P < 0.01). In the H group, the insertional torque were 2.71 ± 1.36 Nm in the CBT screws and 1.58 ± 0.44 Nm in the traditional screws. The CBT screws demonstrated 1.71 times higher torque and statistical significance was achieved (P < 0.01). Positive linear correlations between maximum insertional torque and bone mineral density were found in both technique, the correlation coefficient of traditional screws (r = 0.63, P < 0.01) was higher than that of the CBT screws (r = 0.59, P < 0.01).. The insertional torque using the CBT technique is about 1.7 times higher than the traditional technique.. 2.

Topics: Adult; Aged; Aged, 80 and over; Biomechanical Phenomena; Bone Density; Bone Screws; Female; Humans; Lumbar Vertebrae; Male; Materials Testing; Middle Aged; Spinal Diseases; Spinal Fusion; Torque

A cortical bone trajectory (CBT) is a new pedicle screw trajectory that maximizes the thread contact with cortical bone surface, providing enhanced screw purchase. Despite the increased use of the CBT in the lumbar spine, little is known about the insertion technique for the sacral CBT. The aim of this study was to introduce a novel sacral pedicle screw trajectory. This trajectory engages with denser bone maximally by the screw penetrating the S-1 superior endplate through a more medial entry point than the traditional technique, and also has safety advantages, with the protrusion of the screw tip into the intervertebral disc space carrying no risk of neurovascular injury.. In this study, the CT scans of 50 adults were studied for morphometric measurement of the new trajectory. The entry point was supposed to be the junction of the center of the superior articular process of S-1 and approximately 3 mm inferior to the most inferior border of the inferior articular process of L-5. The direction was straight forward in the axial plane without convergence, angulated cranially in the sagittal plane penetrating the middle of the sacral endplate. The cephalad angle to the sacral endplate, length of trajectory, and safety of the trajectory were investigated. Next, the insertional torque of pedicle screws using this technique was measured intraoperatively in 19 patients and compared with the traditional technique.. The mean cephalad angle in these 50 patients was 30.7° ± 5.1°, and the mean length of trajectory was 31.5 ± 3.5 mm. The CT analysis revealed that the penetrating S-1 endplate technique did not cause any neurovascular injury anteriorly in any case. The new technique demonstrated an average of 141% higher insertional torque than the traditional monocortical technique.. The penetrating S-1 endplate technique through the medial entry point is suitable for the connection of lumbar CBT, has revealed favorable stability for lumbosacral fixation, and has reduced the potential risk of neurovascular injuries.

Topics: Adult; Aged; Bone Screws; Female; Humans; Lumbar Vertebrae; Male; Middle Aged; Radiographic Image Interpretation, Computer-Assisted; Sacrum; Spinal Diseases; Spinal Fusion; Tomography, X-Ray Computed; Torque; Treatment Outcome

This is a retrospective study carried out to evaluate the clinical results of patients with osteoporosis and various spinal diseases treated surgically with polymethylmethacrylate (PMMA)-augmented cannulated pedicle screws, and to compare this method with the needle injection technique in terms of the clinical results and fixation strength.. To report a technique using PMMA-augmented cannulated pedicle screws for fixation in osteoporotic spines and to compare its clinical results and biomechanical characteristics with the needle injection technique.. Many studies have shown that PMMA-augmented pedicle screws can significantly increase the stiffness and strength of the screw. Various designs of cannulated screws have been used for cement augmentation in experimental studies; however, clinical reports using these screws in osteoporotic patients are rare. A practical and reliable technique and optimal screw design have not yet been established.. Forty-five patients (23 women, 22 men), mean age of 71.37 years (range, 53-94 y), with osteoporosis and various spinal diseases underwent spinal decompression and instrumentation with PMMA augmentation of cannulated pedicle screws. Preoperative and postoperative visual analog scale scores for pain and the Oswestry disability index questionnaire data were analyzed. Screw migration, which is the distance from the screw tip to the anterior cortex and the upper endplate of the vertebra, was also evaluated immediately after surgery and at the mean follow-up of 15.9 months. These clinical results were then compared with those reported for the needle injection technique. The pullout strength, insertional, and backout torque of these 2 techniques were compared using osteoporotic synthetic bone (0.12 g/cm).. A total of 255 out of 283 cannulated screws were augmented with PMMA. The mean visual analog scale pain score of these patients improved from 9.5 to 3.1 (P<0.01) and the functional Oswestry disability index score improved from 71% to 28.9% (P<0.01). Kyphotic deformity of the compression fracture group (19 patients) was improved from an average of 9.38 to 3.27 degrees after surgery, and to 5.45 degrees at the final follow-up (P<0.01). There was no significant vertical screw migration when the screws' distances were compared just after the operation and at the final follow-up (P>0.01). However, significant horizontal screw migration was found in lesions below the L2 level (P<0.01). There was no major neurovascular injury, except in 1 patient, who had persistent left thigh pain due to cement leakage at the L1 level, and the symptom was controlled with analgesics. The clinical results of both techniques were satisfactory and there were no significant differences. Although the pullout strength and screw backout torque was significantly higher in the needle injection group (234.1 vs. 187.8 N, 1119.6 vs. 836.7 N mm, respectively), the operation time was shorter and the cement leakage rate was less in the cannulated pedicle screw group than that of the needle injection group (211.4 vs. 296.3 min, 14.05% vs. 26.2%, respectively).. The technique of cannulated pedicle screws with PMMA augmentation used in this study can be an option for osteoporotic patients with various spinal diseases who require spinal instrumentation.

Topics: Aged; Aged, 80 and over; Biomechanical Phenomena; Bone Cements; Bone Screws; Female; Humans; Male; Middle Aged; Osteoporosis; Polymethyl Methacrylate; Retrospective Studies; Spinal Diseases; Spinal Fusion; Torque; Treatment Outcome

In patients with osteoporosis there is always a strong possibility that pedicle screws will loosen. This makes it difficult to select the appropriate osteoporotic patient for a spinal fusion. The purpose of this study was to determine the correlation between bone mineral density (BMD) and the magnitude of torque required to insert a pedicle screw. To accomplish this, 181 patients with degenerative disease of the lumbar spine were studied prospectively. Each underwent dual-energy x-ray absorptiometry (DEXA) and intra-operative measurement of the torque required to insert each pedicle screw. The levels of torque generated in patients with osteoporosis and osteopenia were significantly lower than those achieved in normal patients. Positive correlations were observed between BMD and T-value at the instrumented lumbar vertebrae, mean BMD and mean T-value of the lumbar vertebrae, and mean BMD and mean T-value of the proximal femur. The predictive torque (Nm) generated during pedicle screw insertion was [-0.127 + 1.62 × (BMD at the corresponding lumbar vertebrae)], as measured by linear regression analysis. The positive correlation between BMD and the maximum torque required to insert a pedicle screw suggests that pre-operative assessment of BMD may be useful in determining the ultimate strength of fixation of a device, as well as the number of levels that need to be fixed with pedicle screws in patients who are suspected of having osteoporosis.

Topics: Absorptiometry, Photon; Bone Density; Bone Diseases, Metabolic; Bone Screws; Femur; Humans; Lumbar Vertebrae; Osteoporosis; Prognosis; Prospective Studies; Spinal Diseases; Spinal Fusion; Torque; Treatment Outcome

In reconstruction of the osteoporotic spine, patients often show poor outcome because of pedicle screw failure. This study used osteoporotic and nonosteoporotic vertebrae to determine the difference in fixation strength between pedicle screws inserted straight forward and pedicle screws inserted in an upward trajectory toward the superior end plate (i.e., end-plate screws). There is some evidence to suggest that end-plate screws have a strength advantage. The particular focus was on osteoporotic vertebrae. Thirty-three vertebrae (T10-L2) were harvested. The bone mineral density (BMD) was measured: 15 vertebrae were greater than 0.8 g/cm(2) and designated as nonosteoporotic (average BMD 1.146 ± 0.186 g/cm(2)) and 18 vertebrae were designated as osteoporotic (average BMD 0.643 ± 0.088 g/cm(2)). On one pedicle the screw was inserted straight forward and on the other pedicle the screw was inserted as an end-plate screw. The torque of insertion was measured (Proto 6106 torque screwdriver). Using an MTS Mini Bionix, two types of mechanical testing were carried out on each pedicle: (a) cephalocaudad toggling was first carried out to simulate some physiological type loading: 500 cycles at 0.3 Hz, at ±50 N; and (b) then each pedicle screw was pulled out at a displacement rate of 12.5 cm/min.There was no difference in pullout force between the pedicle screws inserted straight forward and the pedicle screws inserted as end-plate screws. This result applies whether the vertebrae were osteoporotic or nonosteoporotic. For both the straight-forward screws and the end-plate screws, a statistically significant correlation was observed between torque of insertion and pullout force. The results of this experiment indicate that pedicle screws inserted as end-plate screws do not provide a strength advantage over pedicle screws inserted straight forward, whether the vertebrae are osteoporotic or not.

Topics: Aged; Aged, 80 and over; Biomechanical Phenomena; Bone Screws; Female; Humans; Male; Materials Testing; Middle Aged; Orthopedic Procedures; Osteoporosis; Spinal Diseases; Spine; Torque

An in vitro flexibility experiment was performed to compare the biomechanical stability of asymmetrical lumbar pedicle screw fixation (longer hardware attached ipsilaterally to a 1-sided lesion), short and long fixation, and fixation with and without interconnection to the involved vertebra.. Seven human cadaveric specimens (T12-S1) were studied intact; after simulated unilateral lesions were created at L2-3 and L3-4, the segments were stabilized by 1) L2-4 unilateral fixation (L-3 excluded), 2) L2-4 bilateral fixation (L-3 included contralaterally), 3) L2-5 unilateral fixation (L-3 excluded), 4) L2-5 fixation ipsilateral (L-3 excluded) and L2-4 fixation contralateral (L-3 included), 5) L2-5 bilateral fixation (L-3 included contralaterally), and 6) L2-5 bilateral fixation (L-3 excluded). The testing order varied among specimens. Angular range of motion (ROM) and lax zone were recorded optically while loading to 6.0 Nm was created with nonconstraining pure moments.. Unilateral short fixation provided significantly worse stabilization than any other construct tested in all loading modes (p < 0.05, repeated-measures analysis of variance). There was a mean 56% reduction in ROM across the lesion after adding 1 additional level rostrally and caudally. Asymmetrical long/short stabilization provided similar stability to symmetrical long stabilization. Minimal additional stability was gained by including L-3 in the long bilateral fixation construct.. Unilateral fixation is inadequate for stabilizing a 2-level unilateral lesion. Bilateral fixation, whether symmetrical or asymmetrical, provides good stabilization for this injury. It is not important for stability to include the level of the lesion within the long construct contralaterally.

Topics: Adult; Aged; Biomechanical Phenomena; Bone Screws; Cadaver; Equipment Design; Female; Humans; Imaging, Three-Dimensional; Internal Fixators; Lumbar Vertebrae; Male; Materials Testing; Middle Aged; Pliability; Range of Motion, Articular; Spinal Diseases; Spinal Fusion; Torque

The purposes of this study were to determine if the intraoperative insertional torque of pedicle screws correlates with the degree of osteoporosis and if insertional torque can be used as a predictor of screw loosening and clinical results in elderly patients. Pedicle screw fixation was performed in 25 patients. Their mean age at the time of surgery was 72.2 years (range 65-79 years). The mean follow-up period was 2.8 years (range 1.0-4.8 years). The insertional torque of the pedicle screws was measured using a Kannon-type torque wrench with a special connector. In the present study, 136 screws were evaluated. The mean insertional torque was 12.2 +/- 5.0 kgf x cm. A negative relation was found between insertional torque and the grade of osteoporosis. Roentgenograms showed the radiolucency of 18 screws in eight patients. Radiolucency appeared as early as 6 months postoperatively. However, there was no significant relation between insertional torque and the presence of screw loosening. Furthermore, there was no significant difference in the clinical results between patients with low insertional torque and those with high insertional torque. This study demonstrated that intraoperative insertional torque is not an objective predictor of screw loosening or clinical results.

Topics: Aged; Bone Screws; Equipment Design; Equipment Failure; Female; Humans; Intraoperative Care; Lumbar Vertebrae; Male; Osteoporosis; Risk Factors; Spinal Diseases; Torque

The authors evaluated the effects of pilot hole preparation technique on insertional torque and axial pullout resistance in osteoporotic thoracic and lumbar vertebrae.. Using a probe technique and fluoroscopy, 102 pedicle screws were placed in 51 dual-energy x-ray absorptiometry-proven osteoporotic thoracic and lumbar levels. Screws were inserted using the same-size tapping, one-size-under tapping, or no-tapping technique. Insertional torque and axial pullout resistance were measured. Analysis of variance, Fisher exact test, and regression analysis were performed. Same-size tapping decreased pullout resistance in the lumbar spine. There was no effect on pullout resistance in the thoracic spine. Pullout resistance values were lower for all insertion techniques in the upper thoracic spine. Insertional torque and bone mineral density correlated with pullout resistance in the thoracic and lumbar spine.. Tapping decreased pedicle screw pullout resistance in the osteoporotic human lumbar spine, although it did not affect pullout strength in the thoracic spine. Tapping decreased insertional torque in upper thoracic levels. Surgeons should optimize overall construct rigidity when placing thoracic pedicle screws in patients with spinal segment osteoporosis.

Topics: Biomechanical Phenomena; Bone Screws; Cadaver; Female; Humans; Lumbar Vertebrae; Orthopedic Procedures; Osteoporosis; Spinal Diseases; Thoracic Vertebrae; Torque