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author:("Lin, rey-Mo")
1.  A novel method of C1–C2 transarticular screw insertion for symptomatic atlantoaxial instability using a customized guiding block 
Medicine  2016;95(43):e5100.
Atlantoaxial instability treated with the C1-2 transarticular screw fixation is biomechanically more stable; however, the technique demanding and the potential risk of neurovascular injury create difficulties for clinical usage, and there is still lack of clinical experience till now.
We reported an adult female patient with symptomatic atlantoaxial instability due to rheumatoid arthritis that was successfully treated with a bilateral C1–C2 transarticular screw fixation using a customized guiding block. We preoperatively determined the trajectories for bilateral C1–C2 transarticular screws on a 3-dimensional reconstruction model from the computed tomography (CT) and self-developed computer software, and designed a rapid prototyping customized guiding block in order to offer a guide for the entry point and insertion angle of the C1–C2 transarticular screws.
The clinical outcome was good, and the follow-up period was >3 years. The accuracy of the screws is good in comparison with preoperative and postoperative CT findings, and no neurovascular injury occurred.
The patient was accurately and successfully treated with a bilateral C1–C2 transarticular screw fixation using a customized guiding block.
PMCID: PMC5089091  PMID: 27787362
atlantoaxial instability; customized guiding block; transarticular screw
2.  Postural Responses to a Suddenly Released Pulling Force in Older Adults with Chronic Low Back Pain: An Experimental Study 
PLoS ONE  2016;11(9):e0162187.
Chronic low back pain (CLBP), one of the most common musculoskeletal conditions in older adults, might affect balance and functional independence. The purpose of this study was to investigate the postural responses to a suddenly released pulling force in older adults with and without CLBP. Thirty community-dwelling older adults with CLBP and 26 voluntary controls without CLBP were enrolled. Participants were required to stand on a force platform while, with one hand, they pulled a string that was fastened at the other end to a 2-kg or to a 4-kg force in the opposite direction at a random order. The number of times the participants lost their balance and motions of center of pressure (COP) when the string was suddenly released were recorded. The results demonstrated that although the loss of balance rates for each pulling force condition did not differ between groups, older adults with CLBP had poorer postural responses: delayed reaction, larger displacement, higher velocity, longer path length, and greater COP sway area compared to the older controls. Furthermore, both groups showed larger postural responses in the 4-kg pulling force condition. Although aging is generally believed to be associated with declining balance and postural control, these findings highlight the effect of CLBP on reactive balance when responding to an externally generated force in an older population. This study also suggests that, for older adults with CLBP, in addition to treating them for pain and disability, reactive balance evaluation and training, such as reaction and movement strategy training should be included in their interventions. Clinicians and older patients with CLBP need to be made aware of the significance of impaired reactive balance and the increased risk of falls when encountering unexpected perturbations.
PMCID: PMC5021337  PMID: 27622646
3.  Palliative transpedicular partial corpectomy without anterior vertebral reconstruction in lower thoracic and thoracolumbar junction spinal metastases 
The thoracolumbar junction is the transition from a stiff (thoracic spine) to a mobile zone (lumbar spine) and is relatively unstable compared with the thoracic and lumbar portions of the spine. The need for anterior reconstruction after a corpectomy has been emphasized by several authors. However, for patients with a relatively short life expectancy, anterior reconstruction may be unnecessary. Posterior instrumentation alone may be sufficient to provide pain relief and stability for such patients. The goal of this study was to assess the postoperative outcomes and survival rates of patients with tumor metastases of the lower thoracic spine and thoracolumbar junction (T10–L1) who underwent transpedicular partial corpectomy without anterior vertebral reconstruction.
From November 2001 to February 2015, 29 patients diagnosed with symptomatic spinal cord compression caused by tumor metastasis involving T10 to L1 underwent palliative surgery that involved a posterolateral transpedicular partial corpectomy without anterior reconstruction. The surgical indication was neurologic progression. A follow-up was conducted for all of the patients, including reviewing medical records and performing an examination in the outpatient department.
The patients ranged in age from 33 to 83 years (mean, 61.6 years). Neurologic improvement by at least one Frankel grade was noted in 75.9 % of the patients (N = 22). Neither intraoperative mortality nor implant failure was reported. The median survival rate was 7.43 months (range, 0.47–28 months).
The results of this study suggest that the stability of implants can be maintained up to 28 months with satisfying functional outcome after a palliative posterolateral transpedicular partial corpectomy without anterior reconstruction.
PMCID: PMC4504462  PMID: 26183322
Anterior vertebral reconstruction; Cancer; Implant failure; Partial corpectomy; Posterior instrumentation; Posterolateral transpedicular approach; Spinal metastasis; Stability; Survival rate; Thoracolumbar junction tumor
4.  MRI fluid sign is reliable in correlation with osteonecrosis after vertebral fractures: a histopathologic study 
European Spine Journal  2012;22(7):1617-1623.
Magnetic resonance images (MRI) fluid sign and intravertebral vacuum phenomenon of the plain radiograph are considered as the characteristic radiological findings for vertebral osteonecrosis after spinal fractures. We aim to study the association between the radiological and histopathologic findings of vertebral osteonecrosis through the use of an open retrieval of specimens.
Materials and methods
Twenty consecutive patients (54–84 years, mean 73 years) of unstable vertebral compression fractures treated with anterior corpectomy and fusion were included. All the images and pathologies were correlated, especially the histopathologic changes to the fluid sign and vacuum phenomenon.
MRI fluid signs and the histopathologic findings of vertebral osteonecrosis were significantly correlated and both were noted in the first 5 months after injury. The power of the fluid sign in diagnosing vertebral osteonecrosis was better than that of the intravertebral vacuum phenomenon (diagnostic odds ratio 65 vs. 2, sensitivity 86 vs. 50 %, specificity 100 vs. 67 %).
MRI fluid sign is more predictable to diagnose vertebral osteonecrosis in operative case, especially within the initial 5 months after injury.
PMCID: PMC3698360  PMID: 23269528
Vertebral fracture; Fluid sign; Intravertebral vacuum phenomenon; Histopathology; Vertebral osteonecrosis
5.  Epidemiological Survey of Quantitative Ultrasound in Risk Assessment of Falls in Middle-Aged and Elderly People 
PLoS ONE  2013;8(8):e71053.
The risk assessment of falls is important, but still unsatisfactory and time-consuming. Our objective was to assess quantitative ultrasound (QUS) in the risk assessment of falls. Our study was designed as epidemiological cross-sectional study occurring from March 2009 to February 2010 by community survey at a medical center. The participants were collected from systemic sample of 1,200 community-dwelling people (Male/Female = 524/676) 40 years old and over in Yunlin County, Mid-Taiwan. Structural questionnaires including socioeconomic status, living status, smoking and drinking habits, exercise and medical history were completed. Quantitative ultrasound (QUS) at the non-dominant distal radial area (QUS-R) and the left calcaneal area (QUS-C) were measured. The overall prevalence of falls was 19.8%. In men, the independently associated factors for falls were age (OR: 1.04; 95%CI: 1.01∼1.06), fracture history (OR: 1.89; 95%CI: 1.12∼3.19), osteoarthritis history (OR: 3.66; 95%CI: 1.15∼11.64) and speed of sound (OR: 0.99; 95%CI: 0.99∼1.00; p<0.05) by QUS-R. In women, the independently associated factors for falls were current drinking (OR: 3.54; 95%CI: 1.35∼9.31) and broadband ultrasound attenuation (OR: 0.98; 95%CI: 0.97∼0.99; p<0.01) by QUS-C. The cutoffs at -2.5< T-score<-1 derived using QUS-R (OR: 2.85; 95%CI: 1.64∼4.96; p<0.01) in men or T-score ≦-2.5 derived using QUS-C (OR: 2.72; 95%CI: 1.42∼5.21; p<0.01) in women showed an independent association with falls. The lowest T-score derived using either QUS-R or QUS-C was also revealed as an independent factor for falls in both men (OR: 2.13; 95%CI: 1.03∼4.43; p<0.05) and women (OR: 2.36; 95%CI: 1.13∼4.91; p<0.05). Conclusions: Quantitative ultrasounds, measured either at the radial or calcaneal area, are convenient tools by which to assess the risk of falls in middle-aged and elderly people.
PMCID: PMC3737261  PMID: 23951077
6.  Developing functional workspace for the movement of trunk circumduction in healthy young subjects: a reliability study 
The lumbar range of motion has traditionally been used to assess disability in patients with low back disorders. Controversy exists about how movement ranges in static positions or in a single straight plane is related to the functional status of the patients. The trunk circumduction, as the result of neuromuscular coordination, is the integrated movements from three dimensions. The functional workspace stands for the volume of movement configuration from the trunk circumduction and represents all possible positions in three dimensions. By using single quantitative value, the functional workspace substitutes the complicated joint linear or angular motions. The aim of this study is to develop the functional workspace of the trunk circumduction (FWTC) considering possible functional positions in three dimensional planes. The reliability of the trunk circumduction is examined.
Test-retest reliability was performed with 18 healthy young subjects. A three-dimensional (3-D) Motion Analysis System was used to record the trunk circumduction. The FWTC was defined and calculated based on the volume of the cone that was formed as the resultant scanned area of markers, multiplied by the length of the body segment. The statistical analysis of correlation was performed to describe the relation of maximal displacements of trunk circumduction and straight planes: sagittal and coronal.
The results of this study indicate that the movement of trunk circumduction measured by motion analysis instruments is a reliable tool. The ICC value is 0.90-0.96, and the means and standard deviations of the normalized workspace are: C7 0.425 (0.1162); L1 0.843 (0.2965); and knee 0.014 (0.0106). Little correlations between the maximal displacement of trunk circumduction and that of straight planes are shown and therefore suggest different movement patterns exist.
This study demonstrates high statistical reliability for the FWTC, which is important for the potential development as the functional assessment technique. The FWTC provides a single integrated value to represent angular and linear measurements of different joints and planes. Future study is expected to carry out the FWTC to evaluate the amount of workspace for the functional status of patients with low back injuries or patients with spinal surgery.
PMCID: PMC3598346  PMID: 23311750
Trunk circumduction; Motion analysis; Functional workspace
7.  Factors affecting disability and physical function in degenerative lumbar spondylolisthesis of L4–5: evaluation with axially loaded MRI 
European Spine Journal  2009;18(12):1851-1857.
Few studies have investigated the factors related to the disability and physical function in degenerative lumbar spondylolisthesis using axially loaded magnetic resonance imaging (MRI). Therefore, we aimed to investigate the effect of axial loading on the morphology of the spine and the spinal canal in patients with degenerative spondylolisthesis of L4–5 and to correlate morphologic changes to their disability and physical functions. From March 2003 to January 2004, 32 consecutive cases (26 females, 6 males) with degenerative L4–5 spondylolisthesis, grade 1–2, intermittent claudication, and low back pain without sciatica were included in this study. All patients underwent unloaded and axially loaded MRI of the lumbo-sacral spine in supine position to elucidate the morphological findings and to measure the parameters of MRI, including disc height (DH), sagittal translation (ST), segmental angulation (SA), dural sac cross-sectional area (DCSA) at L4–5, and lumbar lordotic angles (LLA) at L1–5 between the unloaded and axially loaded condition. Each patient’s disability was evaluated by the Oswestry Disability Index (ODI) questionnaire, and physical functioning (PF) was evaluated by the Physical Function scale proposed by Stucki et al. (Spine 21:796–803, 1996). Three patients were excluded due to the presence of neurologic symptoms found with the axially loaded MRI. Finally, a total of 29 (5 males, 24 females) consecutive patients were included in this study. Comparisons and correlations were done to determine which parameters were critical to the patient’s disability and PF. The morphologies of the lumbar spine changed after axially loaded MRI. In six of our patients, we observed adjacent segment degeneration (4 L3–L4 and 2 L5–S1) coexisting with degenerative spondylolisthesis of L4–L5 under axially loaded MRI. The mean values of the SA under pre-load and post-load were 7.14° and 5.90° at L4–L5 (listhetic level), respectively. The mean values of the LLA under pre-load and post-load were 37.03° and 39.28°, respectively. There were significant correlations only between the ODI, PF, and the difference of SA, and between PF and the post-loaded LLA. The changes in SA (L4–L5) during axial loading were well correlated to the ODI and PF scores. In addition, the LLA (L1–L5) under axial loading was well correlated to the PF of patients with degenerative L4–L5 spondylolisthesis. We suggest that the angular instability of the intervertebral disc may play a more important role than neurological compression in the pathogenesis of disability in degenerative lumbar spondylolisthesis.
PMCID: PMC2899437  PMID: 19526378
Degenerative lumbar spondylolisthesis; Axially loaded MRI; Disability; Physical functioning; Segmental angulation
8.  Biomechanical analysis of the lumbar spine on facet joint force and intradiscal pressure - a finite element study 
Finite element analysis results will show significant differences if the model used is performed under various material properties, geometries, loading modes or other conditions. This study adopted an FE model, taking into account the possible asymmetry inherently existing in the spine with respect to the sagittal plane, with a more geometrically realistic outline to analyze and compare the biomechanical behaviour of the lumbar spine with regard to the facet force and intradiscal pressure, which are associated with low back pain symptoms and other spinal disorders. Dealing carefully with the contact surfaces of the facet joints at various levels of the lumbar spine can potentially help us further ascertain physiological behaviour concerning the frictional effects of facet joints under separate loadings or the responses to the compressive loads in the discs.
A lumbar spine model was constructed from processes including smoothing the bony outline of each scan image, stacking the boundary lines into a smooth surface model, and subsequent further processing in order to conform with the purpose of effective finite element analysis performance. For simplicity, most spinal components were modelled as isotropic and linear materials with the exception of spinal ligaments (bilinear). The contact behaviour of the facet joints and changes of the intradiscal pressure with different postures were analyzed.
The results revealed that asymmetric responses of the facet joint forces exist in various postures and that such effect is amplified with larger loadings. In axial rotation, the facet joint forces were relatively larger in the contralateral facet joints than in the ipsilateral ones at the same level. Although the effect of the preloads on facet joint forces was not apparent, intradiscal pressure did increase with preload, and its magnitude increased more markedly in flexion than in extension and axial rotation.
Disc pressures showed a significant increase with preload and changed more noticeably in flexion than in extension or in axial rotation. Compared with the applied preloads, the postures played a more important role, especially in axial rotation; the facet joint forces were increased in the contralateral facet joints as compared to the ipsilateral ones at the same level of the lumbar spine.
PMCID: PMC2913991  PMID: 20602783
9.  Mini-open anterior spine surgery for anterior lumbar diseases 
European Spine Journal  2008;17(5):691-697.
Minimally invasive surgeries including endoscopic surgery and mini-open surgery are current trend of spine surgery, and its main advantages are shorter recovery time and cosmetic benefits, etc. However, mini-open surgery is easier and less technique demanding than endoscopic surgery. Besides, anterior spinal fusion is better than posterior spinal fusion while considering the physiological loading, back muscle function, etc. Therefore, we aimed to introduce the modified “mini-open anterior spine surgery” (MOASS) and to evaluate the feasibility, effectiveness and safety in the treatment of various anterior lumbar diseases with this technique. A total of 61 consecutive patients (46 female, 15 male; mean age 58.2 years) from 1997 to 2004 were included in this study, with an average follow-up of 24–52 (mean 43) months. The disease entities included vertebral fracture (20), failed back surgery (13), segmental instability or spondylolisthesis (10), infection (8), herniated disc (5), undetermined lesion for biopsy (4), and hemivertebra (1). Lesions involved 13 cases at T12–L1, 18 at L1–L2, 18 at L2–L3, 22 at L3–L4 and 11 at L4–L5 levels. All patients received a single stage anterior-only procedure for their anterior lumbar disease. We used the subjective clinical results, Oswestry disability index, fusion rate, and complications to evaluate our clinical outcome. Most patients (91.8%) were subjectively satisfied with the surgery and had good-to-excellent outcomes. Mean operation time was 85 (62–124) minutes, and mean blood loss was 136 (minimal-250) ml in the past 6 years. Hospital stay ranged from 4–26 (mean 10.6) days. Nearly all cases had improved back pain (87%), physical function (90%) and life quality (85%). Most cases (95%) achieved solid or probable solid bony fusion. There were no major complications. Therefore, MOASS is feasible, effective and safe for patients with various anterior lumbar diseases.
PMCID: PMC2367411  PMID: 18327620
Mini-open anterior spine surgery; Mini-open; Anterior lumbar interbody fusion; Techniques; Lumbar fusion; ALIF

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