Browsing by Subject "Bone Screws"
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Item Open Access Biomechanical comparison of plantar-to-dorsal and dorsal-to-plantar screw fixation strength for subtalar arthrodesis.(Einstein (Sao Paulo, Brazil), 2020-01) Chaudhari, Nileshkumar; Godoy-Santos, Alexandre Leme; Netto, Cesar de Cesar; Rodriguez, Ramon; Dun, Shouchen; He, Jun Kit; McKissack, Haley; Fleisig, Glenn S; Pires, Eduardo Araujo; Shah, AshishOBJECTIVE:To compare screw fixation strength for subtalar arthrodesis. METHODS:Eight matched pairs of cadaver feet underwent subtalar joint arthrodesis with two 7.3mm cannulated screws. Randomization was used to assign screw orientation, such that one foot in each pair was assigned dorsal to plantar screw orientation (DP Group), and the other foot, plantar to dorsal orientation (PD Group). Standard surgical technique with fluoroscopy was used for each approach. Following fixation, each specimen was loaded to failure with a Bionix ® 858 MTS device, applying a downward axial force at a distance to create torque. Torque to failure was compared between DP and PD Groups using Student's t test, with p=0.05 used to determine statistical significance. RESULTS:Statistical analysis demonstrated that the mean torque to failure slightly favored the DP Group (37.3Nm) to the PD Group (32.2Nm). However, the difference between the two groups was not statistically significant (p=0.55). CONCLUSION:In subtalar arthrodesis, there is no significant difference in construct strength between dorsal-to-plantar and plantar-to-dorsal screw orientation. The approach chosen by the surgeon should be based on factors other than the biomechanical strength of the screw orientation.Item Open Access C-2 neurectomy during atlantoaxial instrumented fusion in the elderly: patient satisfaction and surgical outcome.(Journal of neurosurgery. Spine, 2011-07) Hamilton, D Kojo; Smith, Justin S; Sansur, Charles A; Dumont, Aaron S; Shaffrey, Christopher IObjective
The originally described technique of atlantoaxial stabilization using C-1 lateral mass and C-2 pars screws includes a C-2 neurectomy to provide adequate hemostasis and visualization for screw placement, enable adequate joint decortication and arthrodesis, and prevent new-onset postoperative C-2 neuralgia. However, inclusion of a C-2 neurectomy for this procedure remains controversial, likely due in part to a lack of studies that have specifically addressed whether it affects patient outcome. The authors' objective was to assess the surgical and clinical impact of routine C-2 neurectomy performed with C1-2 segmental instrumented arthrodesis in a consecutive series of elderly patients with C1-2 instability.Methods
Forty-four consecutive patients (mean age 71 years) underwent C1-2 instrumented fusion, including C-1 lateral mass screw insertion. Bilateral C-2 neurectomies were performed. Standardized clinical assessments were performed both pre- and postoperatively. Numbness or discomfort in a C-2 distribution was documented at follow-up. Fusion was assessed using the Lenke fusion grade.Results
Among all 44 patients, mean blood loss was 200 ml (range 100-350 ml) and mean operative time was 129 minutes (range 87-240 minutes). There were no intraoperative complications, and no patients reported new postoperative onset or worsening of C-2 neuralgia postoperatively. Outcomes for the 30 patients with a minimum 13-month follow-up (range 13-72 months) were assessed. At a mean follow-up of 36 months, Nurick grade and pain numeric rating scale scores improved from 3.7 to 1.0 (p < 0.001) and 9.4 to 0.6 (p < 0.001), respectively. The mean postoperative Neck Disability Index score was 7.3%. The fusion rate was 97%, and the patient satisfaction rate was 93%. All 24 patients with preoperative occipital neuralgia reported relief. Seventeen patients noticed C-2 distribution numbness only during examination in the clinic, and 2 patients reported C-2 numbness, but it did not affect their daily function.Conclusions
In this series of C1-2 instrumented arthrodesis in elderly patients, excellent fusion rates were achieved, and patient satisfaction was not negatively affected by C-2 neurectomy. In the authors' experience, C-2 neurectomy enhanced surgical exposure of the C1-2 joint, thereby facilitating hemostasis, placement of instrumentation, and decortication of the joint space for arthrodesis. Importantly, with C-2 neurectomy in the present series, no cases of new onset postoperative C-2 neuralgia occurred, in contrast to a growing number of reports in the literature documenting new-onset C-2 neuralgia without C-2 neurectomy. On the contrary, 80% of patients in the present series had preoperative occipital neuralgia and in all of these patients this neuralgia was relieved following C1-2 instrumented arthrodesis with C-2 neurectomy.Item Open Access Comparison of superior-level facet joint violations during open and percutaneous pedicle screw placement.(Neurosurgery, 2012-11) Babu, Ranjith; Park, Jong G; Mehta, Ankit I; Shan, Tony; Grossi, Peter M; Brown, Christopher R; Richardson, William J; Isaacs, Robert E; Bagley, Carlos A; Kuchibhatla, Maragatha; Gottfried, Oren NBackground
Superior-level facet joint violation by pedicle screws may result in increased stress to the level above the instrumentation and may contribute to adjacent segment disease. Previous studies have evaluated facet joint violations in open or percutaneous screw cases, but there are no reports describing a direct institutional comparison.Objective
To compare the incidence of superior-level facet violation for open vs percutaneous pedicle screws and to evaluate patient and surgical factors that affect this outcome.Methods
We reviewed 279 consecutive patients who underwent an index instrumented lumbar fusion from 2007 to 2011 for degenerative spine disease with stenosis with or without spondylolisthesis. We used a computed tomography grading system that represents progressively increasing grades of facet joint violation. Patient and surgical factors were evaluated to determine their impact on facet violation.Results
Our cohort consisted of 126 open and 153 percutaneous cases. Percutaneous procedures had a higher overall violation grade (P = .02) and a greater incidence of high-grade violations (P = .006) compared with open procedures. Bivariate analysis showed significantly greater violations in percutaneous cases for age < 65 years, obesity, pedicle screws at L4, and 1- and 2-level surgeries. Multivariate analysis showed the percutaneous approach and depth of the spine to be independent risk factors for high-grade violations.Conclusion
This study demonstrates greater facet violations for percutaneously placed pedicle screws compared with open screws.Item Open Access Kickstand Rod Technique for Correcting Coronal Imbalance in Adult Scoliosis: 2-Dimensional Operative Video.(Operative neurosurgery (Hagerstown, Md.), 2020-08) Buell, Thomas J; Buchholz, Avery L; Mazur, Marcus D; Mullin, Jeffrey P; Chen, Ching-Jen; Sokolowski, Jennifer D; Yen, Chun-Po; Shaffrey, Mark E; Shaffrey, Christopher I; Smith, Justin SRestoration of spinal alignment and balance is a major goal of adult scoliosis surgery. In the past, sagittal alignment has been emphasized and was shown to have the greatest impact on functional outcomes. However, recent evidence suggests the impact of coronal imbalance on pain and functional outcomes has likely been underestimated.1,2 In addition, iatrogenic coronal imbalance may be common and frequently results from inadequate correction of the lumbosacral fractional curve.2,3 The "kickstand rod" is a recently described technique to achieve and maintain significant coronal-plane correction.4 Also, of secondary benefit, the kickstand rod may function as an accessory supplemental rod to offload stress and bolster primary instrumentation. This may reduce occurrence of rod fracture (RF) or pseudarthrosis (PA).5 Briefly, this technique involves positioning the kickstand rod on the side of coronal imbalance (along the major curve concavity or fractional curve convexity in our video demonstration). The kickstand rod spans the thoracolumbar junction proximally to the pelvis distally and is secured with an additional iliac screw placed just superior to the primary iliac screw. By using the iliac wing as a base, powerful distraction forces can reduce the major curve to achieve more normal coronal balance. This operative video illustrates the technical nuances of utilizing the kickstand rod technique for correction of severe lumbar scoliosis and coronal malalignment in a 60-yr-old male patient. Alignment correction was achieved and maintained without evidence of RF/PA after nearly 6 mo postoperatively. The patient gave informed consent for surgery and to use imaging for medical publication.Item Open Access Less invasive surgery for treating adult spinal deformities: ceiling effects for deformity correction with 3 different techniques.(Neurosurgical focus, 2014-05) Wang, Michael Y; Mummaneni, Praveen V; Fu, Kai-Ming G; Anand, Neel; Okonkwo, David O; Kanter, Adam S; La Marca, Frank; Fessler, Richard; Uribe, Juan; Shaffrey, Christopher I; Lafage, Virginie; Haque, Raqeeb M; Deviren, Vedat; Mundis, Gregory M; Minimally Invasive Surgery Section of the International Spine Study GroupObject
Minimally invasive surgery (MIS) options for the treatment of adult spinal deformity (ASD) have advanced significantly over the past decade. However, a wide array of options have been described as being MIS or less invasive. In this study the authors investigated a multiinstitutional cohort of patients with ASD who were treated with less invasive methods to determine the extent of deformity correction achieved.Methods
This study was a retrospective review of multicenter prospectively collected data in 85 consecutive patients with ASD undergoing MIS surgery. Inclusion criteria were as follows: age older than 45 years; minimum 20° coronal lumbar Cobb angle; and 1 year of follow-up. Procedures were classified as follows: 1) stand-alone (n = 7); 2) circumferential MIS (n = 43); or 3) hybrid (n = 35).Results
An average of 4.2 discs (range 3-7) were fused, with a mean follow-up duration of 26.1 months in this study. For the stand-alone group the preoperative Cobb range was 22°-51°, with 57% greater than 30° and 28.6% greater than 50°. The mean Cobb angle improved from 35.7° to 30°. A ceiling effect of 23° for curve correction was observed, regardless of preoperative curve severity. For the circumferential MIS group the preoperative Cobb range was 19°-62°, with 44% greater than 30° and 5% greater than 50°. The mean Cobb angle improved from 32° to 12°. A ceiling effect of 34° for curve correction was observed. For the hybrid group the preoperative Cobb range was 23°-82°, with 74% greater than 30° and 23% greater than 50°. The mean Cobb angle improved from 43° to 15°. A ceiling effect of 55° for curve correction was observed.Conclusions
Specific procedures for treating ASD have particular limitations for scoliotic curve correction. Less invasive techniques were associated with a reduced ability to straighten the spine, particularly with advanced curves. These data can guide preoperative technique selection when treating patients with ASD.Item Open Access Monitoring.(Journal of neurosurgery. Spine, 2011-08) Shaffrey, Christopher IItem Open Access Outcomes and complications of extension of previous long fusion to the sacro-pelvis: is an anterior approach necessary?(World neurosurgery, 2013-01) Fu, Kai-Ming G; Smith, Justin S; Burton, Douglas C; Shaffrey, Christopher I; Boachie-Adjei, Oheneba; Carlson, Brandon; Schwab, Frank J; Lafage, Virginie; Hostin, Richard; Bess, Shay; Akbarnia, Behrooz A; Mundis, Greg; Klineberg, Eric; Gupta, Munish; International Spine Study GroupBackground
Patients with previous multilevel spinal fusion may require extension of the fusion to the sacro-pelvis. Our objective was to evaluate the outcomes and complications of these patients, stratified based on whether the revision was performed using a posterior-only spinal fusion (PSF) or combined anterior-posterior spinal fusion (APSF).Methods
A retrospective, multicenter evaluation of adults (>18 years old) with a history of prior spinal fusion for scoliosis (≥4 levels) terminating in the distal lumbar spine requiring extension of fusion to the sacro-pelvis (including iliac fixation in all cases), with minimum 2-year follow-up, was performed. Patients were stratified based on approach (APSF vs. PSF) and inclusion of pedicle subtraction osteotomy (PSO). The PSF group included patients treated with an anterior interbody fusion done through a posterior approach, whereas patients in the APSF group all had both anterior and posterior surgical approaches. Clinical outcomes were based on the Scoliosis Research Society (SRS-22) questionnaire.Results
Between 1995 and 2006, 45 patients (mean age = 49 years) met inclusion criteria, with a mean follow-up of 41.9 months (range 24 to 135 months). Demographic, preoperative, operative, and postoperative radiographic, SRS-22, and follow-up results were similar between APSF (n=30) and PSF (n=15) groups. The APSF group had more complications (13 of 30 vs. 3 of 15) and a greater number of pseudarthrosis (4 of 30 vs. 0 of 15) than the PSF group; however, these differences did not reach statistical significance. Patients treated with a PSO (n=13) had greater sagittal vertical axis correction (7.7 cm vs. 2.2 cm; P=.04) compared with patients not treated with a PSO (n=32). There were no differences in complication rates or follow-up SRS-22 scores based on whether a PSO was performed (P>.05).Conclusions
Among adults with previously treated scoliosis requiring extension to the sacro-pelvis, PSF produced radiographic fusion and clinical outcomes equivalent to APSF, whereas complication rates may be lower. PSO resulted in greater sagittal plane correction, without an increase in overall complication rates.Item Open Access The Impact of Instrumentation and Implant Surface Technology on Cervical and Thoracolumbar Fusion.(Operative neurosurgery (Hagerstown, Md.), 2021-06) Wang, Timothy Y; Mehta, Vikram A; Sankey, Eric W; Shaffrey, Christopher I; Abd-El-Barr, Muhammad M; Than, Khoi DSpinal fusion has undergone significant evolution and improvement over the past 50 yr. Historically, spine fusion was noninstrumented and arthrodesis was based entirely on autograft. Improved understanding of spinal anatomy and materials science ushered in a new era of spinal fusion equipped with screw-based technologies and various interbody devices. Osteobiologics is another important realm of spine fusion, and the evolution of various osteobiologics has perhaps undergone the most change within the past 20 yr. A new element to spinal instrumentation has recently gained traction-namely, surface technology. New data suggest that surface treatments play an increasingly well-recognized role in inducing osteogenesis and successful fusion. Until now, however, there has yet to be a unified resource summarizing the existing data and a lack of consensus exists on superior technology. Here, authors provide an in-depth review on surface technology and its impact on spinal arthrodesis.Item Open Access Time to development, clinical and radiographic characteristics, and management of proximal junctional kyphosis following adult thoracolumbar instrumented fusion for spinal deformity.(Journal of spinal disorders & techniques, 2015-03) Reames, Davis L; Kasliwal, Manish K; Smith, Justin S; Hamilton, D Kojo; Arlet, Vincent; Shaffrey, Christopher IStudy design
A retrospective review.Objective
To study time to development, clinical and radiographic characteristics, and management of proximal junctional kyphosis (PJK) following thoracolumbar instrumented fusion for adult spinal deformity (ASD).Summary of background data
PJK continues to be a common mode of failure following ASD surgery. Although literature exists on possible risk factors, data on management remain limited.Methods
A retrospective review of medical records of 289 consecutive ASD patients who underwent posterior segmental instrumentation incorporating at least 5 segments was conducted. PJK was defined as proximal kyphotic angle >10 degrees.Results
PJK occurred in 32 patients (11%) at a mean follow-up of 34 months (range, 1.3-61.9±19 mo). Sixteen (50%) patients were revised (mean, 1.7 revisions; range, 1-3) at a mean follow-up of 9.6 months (range, 0.7-40 mo); primary indications for revision were pain (n=16), myelopathy (n=6), instability (n=4), and instrumentation protrusion (n=2). Comparison of preindex and postindex surgery radiographic parameters demonstrated significant improvement in mean lumbar lordosis (24 vs. 42 degrees, P<0.001), pelvic incidence-lumbar lordosis mismatch (30 vs. 11 degrees, P<0.001), and pelvic tilt (29 vs. 23 degrees, P<0.011). The mean T5-T12 kyphosis worsened (30 vs. 53 degrees, P<0.001) and the mean global sagittal spinal alignment failed to improve (9.6 vs. 8.0 cm, P=0.76). There was no apparent relationship between the absolute PJK angle and revision surgery (P>0.05).Conclusions
The patients in this series who developed PJK had substantial preoperative positive sagittal malalignment that remained inadequately corrected following surgery, likely resulting from a combination of inadequate surgical correction and a significant compensatory increase in thoracic kyphosis. In the absence of direct relationship between a greater PJK angle and worse clinical outcome, clinical symptoms and neurological status rather than absolute reliance on radiographic parameters should drive the decision to pursue revision surgery.