Nondestructive biomechanical testing was performed on bovine lumbar spines instrumented with multilevel scoliosis type anterior spine constructs.
To determine the biomechanical effects from the ...number of anterior rods (1 vs 2) and the effects of interbody structural support on construct stiffness after anterior multisegmental instrumentation.
Corrective surgery using anterior instrumentation for thoracolumbar and lumbar scoliosis has been performed with single rod and, more recently, with dual rod constructs. The biomechanical effect of one- or two-rod anterior instrumentation systems on construct stiffness and the addition or absence of interbody structural support have not been defined adequately in the literature.
Eight bovine lumbar spines each underwent instrumentation using four different constructs: one rod without interbody support; one rod with titanium mesh interbody support at the L2-L3, L3-L4, and L4-L5 disc spaces; two rods alone; and two rods with interbody support. Nondestructive cyclic testing in flexion-extension (+/-5 Nm), lateral bending (+/-5 Nm), and torsion (+/-2 Nm) were performed. The construct stiffness (Nm/ degrees ) of the four implant configurations was compared.
With the addition of a second rod, the construct was significantly stiffer than a single rod construct in flexion (P = 0.006), extension (P = 0.02), and torsion (P = 0.01), but not in lateral bending. The addition of interbody structural support to the rod systems resulted in significantly stiffer constructs than those without cages in flexion (P = 0.03), but not in the other loading conditions (extension, lateral bending, torsion).
Dual rod constructs were stiffer in torsion and flexion-extension loading than single rod constructs. Neither the number of rods nor the use of structural mesh interbody support had any effect on lateral bending stiffness. However, in a single rod system, the addition of interbody support increased stiffness in flexion. The use of structural support in dual rod constructs may be helpful in "setting" the desired lordosis, but adds little to construct stiffness.
IntroductionMore than 1 million elective total hip and knee replacements are performed annually in the USA with 2% risk of clinical pulmonary embolism (PE), 0.1%–0.5% fatal PE, and over 1000 deaths. ...Antithrombotic prophylaxis is standard of care but evidence is limited and conflicting. We will compare effectiveness of three commonly used chemoprophylaxis agents to prevent all-cause mortality (ACM) and clinical venous thromboembolism (VTE) while avoiding bleeding complications.Methods and analysisPulmonary Embolism Prevention after HiP and KneE Replacement is a large randomised pragmatic comparative effectiveness trial with non-inferiority design and target enrolment of 20 000 patients comparing aspirin (81 mg two times a day), low-intensity warfarin (INR (International Normalized Ratio) target 1.7–2.2) and rivaroxaban (10 mg/day). The primary effectiveness outcome is aggregate of VTE and ACM, primary safety outcome is clinical bleeding complications, and patient-reported outcomes are determined at 1, 3 and 6 months. Primary data analysis is per protocol, as preferred for non-inferiority trials, with secondary analyses adherent to intention-to-treat principles. All non-fatal outcomes are captured from patient and clinical reports with independent blinded adjudication. Study design and oversight are by a multidisciplinary stakeholder team including a 10-patient advisory board.Ethics and disseminationThe Institutional Review Board of the Medical University of South Carolina provides central regulatory oversight. Patients aged 21 or older undergoing primary or revision hip or knee replacement are block randomised by site and procedure; those on chronic anticoagulation are excluded. Recruitment commenced at 30 North American centres in December 2016. Enrolment currently exceeds 13 500 patients, representing 33% of those eligible at participating sites, and is projected to conclude in July 2024; COVID-19 may force an extension. Results will inform antithrombotic choice by patients and other stakeholders for various risk cohorts, and will be disseminated through academic publications, meeting presentations and communications to advocacy groups and patient participants.Trial registrationNCT02810704.
A retrospective radiographic review of 31 patients with congenital spine abnormalities who underwent conventional radiography and advanced imaging studies was conducted.
To analyze the utility of ...three-dimensional computed tomography with multiplanar reformatted images for congenital spine anomalies, as compared with plain radiographs and axial two-dimensional computed tomography imaging.
Conventional radiographic imaging for congenital spine disorders often are difficult to interpret because of the patient's small size, the complexity of the disorder, a deformity not in the plane of the radiographs, superimposed structures, and difficulty in forming a mental three-dimensional image. Multiplanar reformatted and three-dimensional computed tomographic imaging offers many potential advantages for defining congenital spine anomalies including visualization of the deformity in any plane, from any angle, with the overlying structures subtracted.
The imaging studies of patients who had undergone a three-dimensional computed tomography for congenital deformities of the spine between 1992 and 1998 were reviewed (31 cases). All plain radiographs and axial two-dimensional computed tomography images performed before the three-dimensional computed tomography were reviewed and the findings documented. This was repeated for the three-dimensional reconstructions and, when available, the multiplanar reformatted images (15 cases). In each case, the utility of the advanced imaging was graded as one of the following: Grade A (substantial new information obtained), Grade B (confirmatory with improved visualization and understanding of the deformity), and Grade C (no added useful information obtained).
In 17 of 31 cases, the multiplanar reformatted and three-dimensional images allowed identification of unrecognized malformations. In nine additional cases, the advanced imaging was helpful in better visualizing and understanding previously identified deformities. In five cases, no new information was gained. The standard and curved multiplanar reformatted images were best for defining the occiput-C1-C2 anatomy and the extent of segmentation defects. The curved multiplanar reformatted images were especially helpful in keeping the spine from "coming in" and "going out" of the plane of the image when there was significant spine deformity in the sagittal or coronal plane. The three-dimensional reconstructions proved valuable in defining failures of formation.
Advanced computed tomography imaging (three-dimensional computed tomography and curved/standard multiplanar reformatted images) allows better definition of congenital spine anomalies. More than 50% of the cases showed additional abnormalities not appreciated on plain radiographs or axial two-dimensional computed tomography images. Curved multiplanar reformatted images allowed imaging in the coronal and sagittal planes of the entire deformity.
A case report of severe spinal lordosis with marked opisthotonus and retrocollis secondary to dystonia musculorum deformans is presented.
To describe a case of dystonia musculorum deformans with ...progressive spinal lordosis and its surgical treatment.
Four patients with correction of coronal spinal deformity associated with dystonia musculorum deformans have been reported in the literature. No reports of sagittal spinal deformity treated with surgical instrumentation and fusion were found.
A retrospective chart and radiographic review of a single case was conducted.
Orthotic management and pharmacologic therapy with botulinum toxin injections were unsuccessful in controlling the deformity. Severe spinal lordosis (170 degrees ) from occiput to sacrum was corrected surgically, allowing an upright posture.
Dystonia musculorum deformans is a rare condition resulting in coronal or sagittal plane deformities. When other treatment methods are unsuccessful, surgical instrumentation and arthrodesis may correct the deformity and improve function.
Metal-on-metal (MOM) bearings with large head diameter are commonly used for total hip arthroplasty (THA). They provide low wear and a reduced risk of dislocation. Since 2001, we have done 1327 ...primary THAs using this bearing surface. Using revision as an endpoint, survivorship is 94% at 8 years. Of the 17 revisions (1.3%), none have been for dislocation. Five patients (0.3%) have shown evidence of a local reaction to the MOM bearing which contributed to their failure and ultimate revision. All 5 presented with elevated inflammatory indexes and had a purulent-appearing joint effusion at revision. Two showed a necrotic periarticular tissue mass (pseudotumor). The presumed diagnosis of infection and the delay in diagnosis of reaction to the MOM with pathology complicated management.
Instability after primary and revision total hip arthroplasty continues to be problematic for the surgeon. The use of constrained liners, which use a locking mechanism to capture the femoral head, ...has increased to help manage this problem. Constrained liners, however, present problems with acetabular component loosening, dissociation of the liner/shell interface, failure by breakage, and excessive polyethylene wear. Rather than resort to constrained liners, our approach has been to restore joint stability with large-diameter femoral heads. The advantages are increased range of motion due to more favorable head/neck ratio, increased resistance to dislocation due to increased jump distance, and the avoidance of skirted femoral heads. With the addition of cross-linked polyethylene, the volumetric wear associated with large heads is much decreased and makes this a viable option today.
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