Publications by authors named "Chun Po Yen"

Background And Objectives: Current surgical strategies for dumbbell nerve sheath tumors (DNSTs) with cord compression have primarily involved wide spinal exposures with total laminectomy and unilateral facetectomy, often leading to spinal destabilization and requiring fusion, or staged procedures separately addressing the intraspinal and extraforaminal tumor components. This study highlights technical nuances of a novel approach for DNST resection to minimize spinal destabilization and avoid fusion while facilitating safe, single-stage complete resection.

Methods: A retrospective chart review was conducted on patients undergoing DNST resection.

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Adult spinal deformity comprises a heterogeneous group of disorders that primarily affects older patients and can have a significant negative affect on health-related quality of life. Operative treatment for adult spinal deformity typically entails posterior instrumented fusions that have demonstrated the potential to significantly improve health-related quality of life outcomes. However, until fusion is achieved, the instrumentation providing structural support is subject to repetitive cyclical loading that disproportionately fatigues high-stress areas and can result in instrumentation failure.

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Background: Lumbar lordosis distribution has become a pivotal factor in re-establishing the foundational alignment of the lumbar spine. This can directly influence overall sagittal alignment, leading to improved long-term outcomes for patients. Despite the wide availability of hyperlordotic stock cages intended to achieve optimal postoperative alignment, there is a lack of correlation between the lordotic shape of a cage and the resultant intervertebral alignment.

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Background: Literature supports the need for improved techniques to achieve spinopelvic alignment and reduce complication rates in patients with adult spinal deformity (ASD). Personalized interbody devices were developed to address this need and are under evaluation in the multicenter Clinical Outcome Measures in Personalized aprevo (circle R superscript) Spine Surgery (COMPASS (TM suprascript) registry. This report presents interim COMPASS pre- and postoperative sagittal alignment results and complication rates for a subcohort of COMPASS patients diagnosed and surgically treated for spinal deformity.

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Background And Objectives: Current surgical strategies for dumbbell nerve sheath tumors (DNSTs) with cord compression have primarily involved wide spinal exposures with total laminectomy and unilateral facetectomy, often leading to spinal destabilization and requiring fusion, or staged procedures separately addressing the intraspinal and extraforaminal tumor components. This study highlights technical nuances of a novel approach for DNST resection to minimize spinal destabilization and avoid fusion while facilitating safe, single-stage complete resection.

Methods: A retrospective chart review was conducted on patients undergoing DNST resection.

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Objective: Primary rod fracture after surgery for adult spinal deformity (ASD) is a leading cause of revision, with recent prospective multicenter fracture rates reported at 11%-14% by 2 years. Consequently, the addition of supplemental rods has been explored to reduce fractures. Here the authors describe their experience with a novel iliac accessory rod technique in which each accessory rod anchors to an independent iliac bolt caudally via lateral connector, and attaches to the primary rod rostrally via side-to-side connector.

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Article Synopsis
  • Implant-related complications in adult spinal deformity (ASD) surgery lead to significant healthcare costs, with primary rod fractures being a major issue, resulting in up to 40% fracture rates.
  • A new four-rod technique using iliac accessory rods aims to reduce these fractures by redistributing stress at the lumbosacral junction, with additional fixation points for better stability.
  • A case study of a 78-year-old woman demonstrated successful outcomes with this method, showing symptom improvement and corrected spinal alignment after surgery.
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Background And Objectives: Patients with diskitis/osteomyelitis who do not respond to medical treatment or develop spinal instability/deformity may warrant surgical intervention. Irregular bony destruction due to the infection can pose a challenge for spinal reconstruction. The authors report a lateral approach using patient-specific interbody cages combined with posterior or lateral instrumentation to achieve spinal reconstruction for spinal instability/deformity from spondylodiskitis.

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Background: Recovery after surgery intersects physical, psychological, and social domains. In this study we aim to assess the feasibility and usability of a mobile health application called PositiveTrends to track recovery in these domains amongst participants undergoing hip, knee arthroplasty or spine surgery. Our secondary aim was to generate procedure-specific, recovery trajectories within the pain and medication, psycho-social and patient-reported outcomes domain.

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Background: Surgery for adult spinal deformity (ASD) often involves long-segment posterior instrumentation that introduces stress at the proximal junction that can result in proximal junctional kyphosis (PJK) or proximal junctional failure (PJF). Recently, the use of tethers at the proximal junction has been proposed as a means of buffering the transitional stresses and reducing the risk of PJK/PJF. Our objectives are to summarize the clinical literature on proximal junctional tethers for PJK/PJF prophylaxis.

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Study Design: This is a cross-sectional survey.

Objective: The aim was to assess the reliability of a proposed novel classification system for thoracic disc herniations (TDHs).

Summary Of Background Data: TDHs are complex entities varying substantially in many factors, including size, location, and calcification.

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Objective: Previous reports of rod fracture (RF) in adult spinal deformity are limited by heterogeneous cohorts, low follow-up rates, and relatively short follow-up durations. Since the majority of RFs present > 2 years after surgery, true occurrence and revision rates remain unclear. The objectives of this study were to better understand the risk factors for RF and assess its occurrence and revision rates following primary thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis (ASLS) in a prospective series with long-term follow-up.

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Objective: Proximal junctional failure (PJF) is a severe form of proximal junctional kyphosis. Previous reports on PJF have been limited by heterogeneous cohorts and relatively short follow-ups. The authors' objectives herein were to identify risk factors for PJF and to assess its long-term incidence and revision rates in a homogeneous cohort.

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Objective: Primary spinal cord astrocytomas are rare, fatal, and poorly studied.

Methods: This study included a 2-center, retrospective analysis of primary spinal cord astrocytoma patients from 1997 to 2020. Patients with drop metastases or without at least one follow-up were excluded.

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Objective: Because of the challenging anatomic location, corpectomies are performed less often at the fourth lumbar vertebral body than at other levels. Our objective was to review the literature of L4 corpectomy and anterior column reconstruction.

Methods: A literature search in the Medline/PubMed database was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to identify all relevant cases and cases series describing corpectomies of the L4 vertebral body using "lumbar" AND "corpectomy" as search terms.

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Objective: Primary spinal meningiomas represent a rare indolent neoplasm usually situated in the intradural-extramedullary compartment. They have a predilection for afflicting the thoracic spine and most frequently present with sensory and/or motor symptoms. Resection is the first-line treatment for symptomatic tumors, whereas other clinical factors will determine the need for adjuvant therapy.

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Objective: Anterior cervical discectomy and fusion (ACDF) is a safe and effective intervention to treat cervical spine pathology. Although these were originally performed as single-level procedures, multilevel ACDF has been performed for patients with extensive degenerative disc disease. To date, there is a paucity of data regarding outcomes related to ACDFs of 3 or more levels.

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Objective: Advancements in less invasive lateral retropleural/retroperitoneal approaches aim to address the limitation of posterolateral approaches and avoid complications associated with anterior open thoracotomy or thoracoabdominal approaches.

Methods: Consecutive patients treated with a mini-open lateral approach for thoracic or thoracolumbar anterior column pathologies were analyzed in a retrospective case series including clinical and radiographic outcomes. Special attention is given to operative techniques and surgical nuances.

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Background: The "kickstand rod technique" has been recently described for achieving and maintaining coronal correction in adult spinal deformity (ASD). Kickstand rods span scoliotic lumbar spine from the thoracolumbar junction proximally to a "kickstand iliac screw" distally. Using the iliac wing as a base, kickstand distraction produces powerful corrective forces.

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Objective: Sacral insufficiency fracture after lumbosacral (LS) arthrodesis is an uncommon complication. The objective of this study was to report the authors' operative experience managing this complication, review pertinent literature, and propose a treatment algorithm.

Methods: The authors analyzed consecutive adult patients treated at their institution from 2009 to 2018.

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Adolescent idiopathic scoliosis patients treated with spinal fusion may develop adjacent segment disease and curve progression into adulthood. Revision operations can be challenging, especially for adult patients treated with outdated instrumentation such as sublaminar hooks and/or wires. The authors demonstrate revision lumbar spine surgery in a 38-year-old female with scoliosis progression from junctional degeneration below a prior T5-L3 posterior instrumented arthrodesis with a hook-and-rod wire system.

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Three-column osteotomies (3COs) can achieve significant alignment correction when revising fixed sagittal plane deformities; however, the technique is associated with high complication rates. The authors demonstrate staged anterior-posterior surgery with L5-S1 ALIF (below a prior L3-5 fusion) and multilevel Smith-Petersen osteotomies to circumvent the morbidity associated with 3CO. The patient was a 67-year-old male with three prior lumbar surgeries who presented with back and leg pain.

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Background: Neoplastic, traumatic, infectious, and degenerative pathologies affecting the thoracolumbar junction pose a unique challenge to spine surgeons. Posterior or anterior approaches have traditionally been utilized to treat these lesions. Although minimally invasive surgeries through a lateral approach to the thoracic or lumbar spine have gained popularity, lateral access to the thoracolumbar junction remains technically challenging due to the overlying diaphragm positioned at the interface of the peritoneum and pleura.

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Restoration 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.

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Objective: Prior reports have demonstrated the efficacy of surgical correction for adult lumbar scoliosis. Many of these reports focused on mild to moderate scoliosis. The authors' objective was to report their experience and to assess outcomes and complications after deformity correction for severe adult scoliosis.

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