Publications by authors named "Mohd Imran Yusof"

17 Publications

  • Page 1 of 1

Feasibility of Unilateral Approach for Bilateral Decompressive Endoscopic Spinal Surgery for Lumbar Stenosis to Improve Back and Leg Pain: A Consecutive Single-Center Series of 60 Patients.

Front Surg 2020 8;7:507954. Epub 2020 Dec 8.

Hospital Universiti Sains Malaysia, Universiti Sains Malaysia, Kota Bharu, Malaysia.

Endoscopic surgery is one of the methods that achieve the goal of decompression while minimizing collateral tissue damage. Its efficacy and safety have been supported by numerous studies. There is a plethora of studies on lumbar stenosis regarding the outcomes and related issues in endoscopic spine surgery. However, few studies evaluated the outcome of the decompressive lumbar spine surgery. The present study aims to analyze the outcome of a unilateral approach to endoscopic surgery for lumbar stenosis using the visual analog scale (VAS), the Oswestry Disability Index (ODI), and MacNab's criteria. This is a retrospective study (level IV) conducted between January 2009 and December 2013 on 60 patients who underwent endoscopic interlaminar decompressive spine surgery (Destandau method) for lumbar degenerative spinal stenosis in the Hospital Universiti Sains Malaysia. The clinical outcome was measured pre-operatively and post-operatively for VAS: for back and leg pain, motor and sensory grading, the ODI, and MacNab's criteria. A paired -test was used for statistical analysis. The mean age of patients was 60.82 years comprising 23 males (38.3%) and 37 females (61.7%). The mean follow-up period was 30.1 months (range = 17.2-43 months). The mean operation time was 183.6 min (ranging from 124.8 to 242.4 min), and the mean blood loss was 150.18 mL (ranging from 30.82 to 269.54 mL). Post-operatively, mean hospital stay was 2.45 days (ranging from 1.34 to 3.56 days). The most frequently involved level was L4/L5 in 51 patients (52.6%), followed by L3/L4 in 19 patients (19.6%), L5/S1 in 24 patients (24.7%), and L2/L3 in three patients (3.1%). Improvement in the post-operative VAS for back and leg pain and the ODI for pre-operation and post-operation was statistically significant ( < 0.001). Conversely, the reduction in neurological status was statistically insignificant. Based on MacNab's criteria, 88.4% showed excellent to good outcomes. To summarize, unilateral percutaneous endoscopic spine surgery to achieve the bilateral decompression in lumbar stenosis provides excellent yet safe and effective outcomes. It improves back and leg pain and patients' function significantly.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fsurg.2020.507954DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7753151PMC
December 2020

Computed Tomographic Morphometric Analysis of C1 and C2 for Lamina Cross Screw Placement in Malay Ethnicity.

Asian Spine J 2021 Feb 8;15(1):1-8. Epub 2020 Apr 8.

Department of Radiology, Hospital Universiti Sains Malaysia, Kota Bharu, Malaysia.

Study Design: This is an observational study of computed tomography (CT) data.

Purpose: The C1 and C2 laminas in the Malaysian Malay population were analyzed for the feasibility of fitting 3.5-mm laminar screws in a cross configuration.

Overview Of Literature: Morphometric analysis of the C1 and C2 laminas has been performed for various populations but not for the Malaysian Malay population.

Methods: A total of 330 CT cervical images were measured to establish the bicortical diameter of the C1 and C2 laminas as well as their height and length. The C1 posterior tubercle bicortical diameter and height were also determined from these images. All parameters were measured up to 0.1 mm, and statistical analysis was performed using IBM SPSS Statistics ver. 24.0 (IBM Corp., Armonk, NY, USA). An independent t -test and the Pearson chi-square test were used to determine the mean difference and screw acceptance.

Results: The means of the C1 lamina measurements were 5.79±1.19 mm in diameter, 9.76±1.51 mm in height, and 20.70±1.86 mm in length. The means of the measurements of the posterior tubercle were 7.20±1.88 mm in diameter and 10.51±1.68 mm in height. The means of the C2 lamina measurements were 5.74±1.31 mm in diameter, 11.76±1.69 mm in height, and 24.96±2.56 mm in length. Overall 65.5% of C1 and 80.3% of C2 laminas are able to accept 3.5-mm screws in a cross configuration. Screw acceptability is similar between the right and left sides (p >0.05). However, males have a higher screw acceptability compared with females (p <0.05), except for the C2 left lamina.

Conclusions: It is feasible to insert a 3.5-mm screw in a cross configuration in the C1 and C2 laminas of the Malaysian Malay population, especially in males. However, a CT scan should be performed prior to the operation to determine screw acceptability and to estimate screw sizes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.31616/asj.2019.0242DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7904487PMC
February 2021

Does Vertical Ground Reaction Force of the Hip, Knee, and Ankle Joints Change in Patients with Adolescent Idiopathic Scoliosis after Spinal Fusion?

Asian Spine J 2018 Apr 16;12(2):349-355. Epub 2018 Apr 16.

Department of Orthopaedics, Universiti Sains Malaysia, Kubang Kerian, Malaysia.

Study Design: Comparative cross-sectional study.

Purpose: We measured the vertical ground reaction force (vGRF) of the hip, knee, and ankle joints during normal gait in normal patients, adolescent idiopathic scoliosis (AIS) patients with a Cobb angle <40° and in AIS patients with spinal fusion. We aimed to investigate whether vGRF in the aforementioned joints is altered in these three groups of patients.

Overview Of Literature: vGRF of the lower limb joints may be altered in these groups of patients. Although it is known that excessive force in the joints may induce early arthritis, there is limited relevant information in the literatures.

Methods: We measured vGRF of the hip, knee, and ankle joints during heel strike, early stance, mid stance, and toe-off phases in normal subjects (group 1, n=14), AIS patients with Cobb angle <40° (group 2, n=14), and AIS patients with spinal fusion (group 3, n=13) using a gait analysis platform. Fifteen auto-reflective tracking markers were attached to standard anatomical landmarks in both the lower limbs. The captured motion images were used to define the orientations of the body segments and force exerted on the force plate using computer software. Statistical analysis was performed using independent t-test and analysis of variance to examine differences between the right and left sides as well as those among the different subject groups.

Results: The measurements during the four gait phases in all the groups did not show any significant difference (>0.05). In addition, no significant difference was found in the vGRF measurements of all the joints among the three groups (>0.05).

Conclusions: A Cobb angle <40° and spinal fusion did not significantly create imbalance or alter vGRF of the lower limb joints in AIS patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4184/asj.2018.12.2.349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913028PMC
April 2018

Osteoarticular and soft-tissue melioidosis in Malaysia: clinical characteristics and molecular typing of the causative agent.

J Infect Dev Ctries 2017 Jan 30;11(1):28-33. Epub 2017 Jan 30.

School of Medical Sciences, Universiti Sains Malaysia, Kelantan, Malaysia.

Introduction: Melioidosis involving bone, joints, and soft tissue is rare and reported usually following dissemination of disease from infection elsewhere in the body; to a lesser degree, it can also be reported as the primary manifestation of melioidosis.

Methodology: The orthopedic registry at Hospital University Sains Malaysia from 2008 until 2014 was retrospectively reviewed and was followed by molecular typing of Burkholderia pseudomallei.

Results: Out of 20 cases identified, 19 patients were confirmed to have osteoarticular and/or soft-tissue melioidosis. The majority of the patients were males (84%), and 16 patients had underlying diabetes mellitus with no significant estimated risk with the disease outcomes. Bacterial genotype was not associated with the disease as a risk. Death was a significant outcome in patients with bacteremic infections (p = 0.044).

Conclusion: Patients with lung or skin melioidosis require careful treatment follow-up to minimize the chance for secondary osteoarticular infection. Human risk factors remain the leading predisposing factors for melioidosis. Early laboratory and clinical diagnosis and acute-phase treatment can decrease morbidity and mortality.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3855/jidc.7612DOI Listing
January 2017

Relationship between pulmonary function and degree of spinal deformity, location of apical vertebrae and age among adolescent idiopathic scoliosis patients.

Singapore Med J 2016 Jan;57(1):33-8

Department of Orthopedics, School of Medical Sciences, Universiti Sains Malaysia, Kelantan, Malaysia.

Introduction: This retrospective review aimed to examine the relationship between preoperative pulmonary function and the Cobb angle, location of apical vertebrae and age in adolescent idiopathic scoliosis (AIS). To our knowledge, there have been no detailed analyses of preoperative pulmonary function in relation to these three factors in AIS.

Methods: A total of 38 patients with thoracic or thoracolumbar scoliosis were included. Curvature of spinal deformity was measured using the Cobb method. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were used to evaluate preoperative pulmonary function. Statistical methods were used to analyse the relationship between preoperative pulmonary function and the factors that may contribute to poor pulmonary function.

Results: The mean age of the patients was 16.68 ± 6.04 years. An inverse relationship was found between the degree of the Cobb angle and FVC as well as FEV1; however, the relationships were not statistically significant (p = 0.057 and p = 0.072, respectively). There was also a trend towards a significant negative correlation between the thoracic curve and FVC (p = 0.014). Patients with larger thoracic curves had lower pulmonary function. A one-year increase in age significantly decreased FVC by 1.092 units (p = 0.044). No significant relationship between age and preoperative FEV1 was found. The median FVC was significantly higher in patients with affected apical vertebrae located at levels L1-L3 than at T6-T8 or T9-T12 (p = 0.006).

Conclusion: Lung function impairment was seen in more severe spinal deformities, proximally-located curvature and older patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.11622/smedj.2016009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4728701PMC
January 2016

Reduced nitric oxide-mediated relaxation and endothelial nitric oxide synthase expression in the tail arteries of streptozotocin-induced diabetic rats.

Eur J Pharmacol 2016 Feb 26;773:78-84. Epub 2016 Jan 26.

Pharmacology Vascular Laboratory, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu, Malaysia. Electronic address:

Diabetes is associated with endothelial dysfunction, which is characterized by impaired endothelium-dependent relaxations. The present study aimed to examine the role of nitric oxide (NO), prostacyclin and endothelium-dependent hyperpolarization (EDH), in the relaxation of ventral tail arteries of rats under diabetic conditions. Relaxations of tail arteries of control and diabetic rats were studied in wire myograph. Western blotting and immunostaining were used to determine the presence of proteins. Acetylcholine-induced relaxations were significantly smaller in arteries of diabetic compared to control rats (Rmax; 70.81 ± 2.48% versus 85.05 ± 3.15%). Incubation with the combination of non-selective cyclooxygenase (COX) inhibitor, indomethacin and potassium channel blockers, TRAM 34 and UCL 1684, demonstrated that NO-mediated relaxation was attenuated significantly in diabetic compared to control rats (Rmax; 48.47 ± 5.84% versus 68.39 ± 6.34%). EDH-type (in the presence of indomethacin and NO synthase inhibitor, LNAME) and prostacyclin-mediated (in the presence of LNAME plus TRAM 34 and UCL 1684) relaxations were not significantly reduced in arteries of diabetic compared to control rats [Rmax: (EDH; 17.81 ± 6.74% versus 34.16 ± 4.59%) (prostacyclin; 15.85 ± 3.27% versus 17.23 ± 3.75%)]. Endothelium-independent relaxations to sodium nitroprusside, salbutamol and prostacyclin were comparable in the two types of preparations. Western blotting and immunostaining indicated that diabetes diminished the expression of endothelial NO synthase (eNOS), while increasing those of COX-1 and COX-2. Thus, since acetylcholine-induced NO-mediated relaxation was impaired in diabetes because of reduced eNOS protein expression, pharmacological intervention improving NO bioavailability could be useful in the management of diabetic endothelial dysfunction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ejphar.2016.01.013DOI Listing
February 2016

Endothelium dependent hyperpolarization-type relaxation compensates for attenuated nitric oxide-mediated responses in subcutaneous arteries of diabetic patients.

Nitric Oxide 2016 Feb 6;53:35-44. Epub 2016 Jan 6.

Pharmacology Vascular Laboratory, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kota Bharu, Malaysia. Electronic address:

Diabetes impairs endothelium-dependent relaxations. The present study evaluated the contribution of different endothelium-dependent relaxing mechanisms to the regulation of vascular tone in subcutaneous blood vessels of humans with Type 2 diabetes mellitus. Subcutaneous arteries were isolated from tissues of healthy controls and diabetics. Vascular function was determined using wire myography. Expressions of proteins were measured by Western blotting and immunostaining. Endothelium-dependent relaxations to acetylcholine were impaired in arteries from diabetics compared to controls (P = 0.009). Acetylcholine-induced nitric oxide (NO)-mediated relaxations [in the presence of an inhibitor of cyclooxygenases (COX; indomethacin) and small and intermediate conductance calcium-activated potassium channel blockers (UCL1684 and TRAM 34, respectively)] were attenuated in arteries from diabetics compared to controls (P < 0.001). However, endothelium-dependent hyperpolarization (EDH)-type relaxations [in the presence of indomethacin and the NO synthase blocker, l-NAME] were augmented in arteries from diabetics compared to controls (P = 0.003). Endothelium-independent relaxations to sodium nitroprusside (NO donor) and salbutamol (β-adrenoceptor agonist) were preserved, but those to prostacyclin were attenuated in diabetics compared to controls (P = 0.017). In arteries of diabetics, protein expressions of endothelial NO synthase, prostacyclin synthase and prostacyclin receptors were decreased, but those of COX-2 were increased. These findings suggest that in human diabetes, the impairment of endothelium-dependent relaxations is caused by a diminished NO bioavailability; however, EDH appears to compensate, at least in part, for this dysfunction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.niox.2015.12.007DOI Listing
February 2016

The morphometric study of l3-L4 and L4-L5 lumbar spine in Asian population using magnetic resonance imaging: feasibility analysis for transpsoas lumbar interbody fusion.

Spine (Phila Pa 1976) 2014 Jun;39(14):E811-6

*Spine Unit, Department of Orthopaedics and †Department of Radiology, School of Medical Science USM, Kubang Kerian, Kelantan, Malaysia.

Study Design: Cross-sectional study on the measurement of relevant magnetic resonance imaging parameters in 100 patients presented for lumbar spine assessment.

Objective: To determine anatomical position of lumbar plexus and major blood vessels in relation to vertebral body and anterior edge of psoas muscle at L3-L4 and L4-L5 and to define the safe working zone for transpsoas approach for lumbar fusion.

Summary Of Background Data: Lateral transpsoas lumbar interbody fusion has been shown to be safe and provides alternative for lumbar fusion. However, proximity of neurovascular structures may not allow a safe passage for this procedure in the Asian population.

Methods: Relevant parameters were measured from axial magnetic resonance images and analyzed, including the psoas muscle and vertebrae endplate diameters, lumbar plexus and psoas muscle distance, lumbar plexus and vertebra body distance, and vena cava to the anterior vertebrae body diameters.

Results: The mean anteroposterior diameters of the right and left psoas muscle ranged from 44.0 to 58.6 mm and 44.8 to 54.0 mm, respectively. The mean anteroposterior diameters of vertebra endplate of L3, L4, and L5 were 38.2 mm, 39.3 mm, and 41.4 mm, respectively. The mean distance of posterior border of vena cava from the vertebra body was 4.5 mm at L3-L4 and 14.1 mm at L4-L5.

Conclusion: L3-L4 fusion is feasible at both sides in both sexes; however, at L4-L5 level, the procedure is feasible only on the left side. The safe working zone for transpsoas approach to lumbar spine is significantly narrower at L4-L5 in both sexes. Anterior edge of psoas muscle can be used as a reliable guide to locate lumbar plexus within psoas muscle.

Level Of Evidence: N/A.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/BRS.0000000000000368DOI Listing
June 2014

Reduced expression of prostacyclin synthase and nitric oxide synthase in subcutaneous arteries of type 2 diabetic patients.

Tohoku J Exp Med 2013 11;231(3):217-22

Pharmacology Vascular Laboratory, School of Medical Sciences, Universiti Sains Malaysia, Health Campus.

Diabetic endothelial dysfunction is characterized by impaired endothelium-dependent relaxation. In this study, we measured the expression of endothelial nitric oxide synthase (eNOS), cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), prostacyclin synthase (PGIS), and prostacyclin receptor (IP) in subcutaneous arteries of type-2 diabetic and non-diabetic patients. Subcutaneous arteries were dissected from tissues from seven diabetics (4 males and 3 females) and seven non-diabetics (5 males and 2 females) aged between 18 to 65 years, who underwent lower limb surgical procedures. Diabetics had higher fasting blood glucose compared to non-diabetics, but there were no differences in blood pressure, body mass index and age. Patients were excluded if they had uncontrolled hypertension, previous myocardial infarction, coronary heart disease, renal or hepatic failure and tumor. The relative expression levels of eNOS, COX-1, COX-2, PGIS and IP receptor were determined by Western blotting analysis, normalized with the β-actin level. Increased expression of COX-2 was observed in subcutaneous arteries of diabetics compared to non-diabetics, whereas the expression levels of eNOS and PGIS were significantly lower in diabetics. There were no significant differences in expression levels of COX-1 and IP receptor between the two groups. Immunohistochemical study of subcutaneous arteries showed that the intensities of eNOS and PGIS staining were lower in diabetics, with higher COX-2 staining. In conclusion, type-2 diabetes is associated with higher COX-2 expression, but lower eNOS and PGIS expression in subcutaneous arteries. These alterations may lead to impaired endothelium-dependent vasodilatation, and thus these proteins may be potential targets for protection against the microvascular complications of diabetes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1620/tjem.231.217DOI Listing
November 2013

Translaminar screw fixation of the cervical spine in Asian population: feasibility and safety consideration based on computerized tomographic measurements.

Surg Radiol Anat 2012 Apr 21;34(3):203-7. Epub 2011 Sep 21.

Spine Unit, Department of Orthopaedics, School of Medical Science, Universiti Sains Malaysia, 16150, Kubang Kerian, Kelantan, Malaysia.

Purpose: Cervical translaminar screw fixation has been shown to be safe, efficient and provides alternative for cervical fixation. However, its use in the Asian population should be considered cautiously because the cervical lamina diameter may not be adequate to accommodate the standard lamina screw size. We studied the average transverse lamina diameter of the cervical spine in the Malaysian population to evaluate the feasibility and safety of lamina screw fixation in this population.

Methods: The measurements of the cervical lamina were performed on CT images. The diameters were defined as the most inner or outer diameter of the lamina, taken perpendicular to the axis of the lamina and measured in millimeters up to 0.1 mm.

Results: The mean transverse inner diameter of the lamina of C2, C3, C4, C5, C6 and C7 was 3.4, 2.0, 1.7, 1.9, 2.3 and 3.4 mm, respectively. The lamina of C2 and C7 has the largest transverse inner diameter and the lamina of C4 the smallest. The mean transverse outer diameter of the lamina of C2, C3, C4, C5, C6 and C7 was 5.6, 3.5, 3.1, 3.1, 3.9 and 5.8 mm, respectively. The lamina of C7 has the largest transverse outer diameter and the lamina of C4 and C5 the smallest.

Conclusions: Translaminar fixation using a 3.5 screw should be attempted with caution in Asian population. Pre-operative CT scan evaluation is mandatory before translaminar screw fixation is attempted.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00276-011-0869-8DOI Listing
April 2012

Predicted cervical canal enlargement and effective cord decompression following expansive laminoplasty using cervical magnetic resonance imaging.

Surg Radiol Anat 2011 Mar 24;33(2):109-15. Epub 2010 Jul 24.

Spine Unit, Department of Orthopaedics, School of Medical Science, USM, 16150 Kubang Kerian, Kelantan, Malaysia.

Background: Posterior translation of the spinal cord occurs passively following laminoplasty with the presence lordotic spine and availability of a space for the spinal cord to shift. This study is to predict the distance of posterior spinal cord migration after expansive laminoplasty at different cervical levels based on measurement of posterior translation of the spinal cord in normal cervical morphometry.

Methods: Measurements were performed from C34, C45, C56 and C67 disc using magnetic resonance imaging (MRI) images. Apical level of the cervical curve, lordotic angle, spinal cord diameter, spinal canal diameter, space anterior to the cord and spinal canal/cord ratio were determined before and after postulated laminoplasty. Statistical analysis was performed to assess the significance of the canal enlargement and effective spinal cord decompression at each level.

Results: The predicted spinal canal decompression achieved at C34, C4C5, C56 and C67 levels were 48.8, 71.9, 84 and 86.5%, respectively. The mean measurement of spinal canal after laminoplasty was 16.7 mm with spinal canal diameter increased between 3.5 and 5.6 mm. Space anterior to the cord after laminoplasty increased to between 8.6 and 10.9 mm. There was significant correlation between Cobb's angle and spinal canal diameter post laminoplasty at C45, C56 and C67 but no significant correlation between Cobb's angle and space anterior to the cord post laminoplasty was found.

Conclusions: Laminoplasty may produce larger canal expansion at the lower cervical spine compared to the upper cervical area; therefore, the outcomes of those who have predominantly higher cervical myelopathy were inferior to those who have lower cervical myelopathy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00276-010-0704-7DOI Listing
March 2011

Morphological comparison between adolescent and adult lumbar pedicles using computerised tomography scanning.

Surg Radiol Anat 2010 Jul 3;32(6):587-92. Epub 2010 Jan 3.

Department of Radiology, School of Medical Science, Universiti Sains Malaysia (USM), Jalan Raja Perempuan Zainab 2, 16150, Kubang Kerian, Kelantan, Malaysia.

Background: To study the morphological difference between the lumbar pedicle in adolescent and adult groups as only less information is known about their pedicle morphology, especially in Malaysian population.

Methods: The pedicle parameters of the lumbar spine in adolescent and adult groups including transverse outer pedicle diameter, transverse inner pedicle diameters, medial wall cortical thickness, lateral wall cortical thickness, pedicle length, transverse pedicle angle and sagittal pedicle angle were measured using computerised tomography (CT) scanning. The measurements in both groups were compared and analysed using statistical method.

Results: In adolescent group, the mean transverse outer diameter was 8.9 +/- 1.2 mm, transverse inner diameter was 6.3 +/- 1.2 mm, medial cortical thickness was 1.6 +/- 1.2 mm, lateral cortical thickness was 1.3 +/- 1.2 mm, pedicle length was 41.7 +/- 3.8 mm, transverse angle was 20.0 +/- 2.5 degrees and sagittal angle was 16.0 +/- 1.7 degrees . In adult group, the mean transverse outer diameter was 9.8 +/- 1.3 mm, transverse inner diameter was 7.0 +/- 1.2 mm, medial cortical thickness was 1.7 +/- 1.2 mm, lateral cortical thickness was 1.4 +/- 1.6 mm, pedicle length was 44.8 +/- 5.0 mm, transverse angle was 21.7 +/- 2.3 degrees and sagittal angle was 17.4 +/- 1.7 degrees . Comparing the mean of the two age groups, all the measurements were significantly smaller (p < 0.05) in the adolescent patients.

Conclusions: Pedicle morphology in adolescent and adult population is different in all parameters, especially in males. Understanding of specific pedicle morphology for each group is imperative for safety in spinal procedures using pedicle route.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00276-009-0612-xDOI Listing
July 2010

Topology optimisation of spinal interbody cage for reducing stress shielding effect.

Comput Methods Biomech Biomed Engin 2010 Jun;13(3):319-26

School of Mechanical Engineering, Universiti Sains Malaysia, Engineering Campus, 14300, Nibong Tebal, Pulau Pinang, Malaysia.

The stress shielding effect is an event in which the replacement implant limits the load transferred to bone and the ineffective stress in the vertebrae causes bony growth to cease. In the present study, a 3D finite element L4-L5 model was developed and subjected to a 1200 N compression preload. Five groups of muscle forces were applied on L4 under flexion-extension, lateral bending and axial rotation. Topology optimisation was employed for reducing the stress shielding effect by removing the ineffective material from the design domain. The optimised design was designed with polyaryletheretherketone (PEEK) titanium and cortical materials to encounter the shielding response. The stress responses show that the new design increased the stress magnitude by at least 17.10, 18.11 and 18.43% in 4 Nm of flexion-extension, lateral bending and axial rotation, respectively. In conclusion, the material factor did not significantly alter the stress magnitude, but volume was the key factor in reducing the stress shielding effect.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/10255840903208189DOI Listing
June 2010

Computed tomographic morphometry of thoracic pedicles: safety margin of transpedicular screw fixation in malaysian malay population.

Spine (Phila Pa 1976) 2006 Jul;31(16):E545-50

Spine Unit, Department of Orthopaedic Surgery, School of Medical Sciences, Universiti Sains Malaysia, Kelantan, Malaysia.

Study Design: A cross-sectional study of thoracic pedicle morphometry (T1-T12) of 180 Malaysian Malay patients obtained from computed tomographic scan.

Objectives: To determine the safety margin in the placement of thoracic transpedicular screw in the Malay population.

Summary Of The Background Data: Previous studies have shown a significantly smaller thoracic pedicular parameters in Asians compared with whites. The safety margin in the placement of thoracic transpedicular screw in our population therefore needs to be defined.

Methods: T1-T12 vertebral pedicles were studied in 180 Malay ethnic patients (age range, 18-80 years). The following parameters were studied: transverse outer pedicle diameter, transverse inner pedicle diameter, transverse pedicle angle, chord length, pedicle length, and pedicle cortical thickness. The data obtained were statistically analyzed using Student's t test and ANOVA test.

Results: Female patients have significantly smaller dimensions in most of the parameters measured compared with male patients. However, no significant difference was found between age groups. Transverse outer pedicle diameter were widest at T1 (male, 8.42 mm; female, 7.56 mm) and narrowest at T4 (male, 4.56 mm; female, 3.95 mm). Pedicle diameters of less than 5.5 mm were commonly seen at T4 followed by T5, T6, T7, T8, and T9. A significant percentage of patients have an outer diameter of less than 4.5 mm from T4-T7. The medial cortices were 50% thicker than the lateral cortices at most levels. Chord lengths were maximum at T8 and minimum at T1. Transverse pedicle angle were widest at T1 and less than 5 degrees from T7-T12.

Conclusions: The results suggest that the current pedicle screw system is not suitable for the majority of Malay population, especially at midthoracic level. The smaller pedicle measurements in Malays may be attributed to their shorter body built compared with whites.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/01.brs.0000225978.97652.e0DOI Listing
July 2006

Computerized tomographic measurement of the cervical pedicles diameter in a Malaysian population and the feasibility for transpedicular fixation.

Spine (Phila Pa 1976) 2006 Apr;31(8):E221-4

Spine Unit, Department of Orthopaedics, School of Medical Science USM, Kelantan, Malaysia.

Study Design: The cervical pedicle diameter size differs between Asians and non-Asians. The authors studied the transverse pedicle diameter of the C2-C7 of the cervical spine in a Malaysian population using computerized tomography (CT) measurements. The transverse diameter of the pedicle is the determinant of the feasibility of this technique because the sagittal diameter of the pedicle has been wider than the transverse pedicle diameter.

Objectives: To study the average transverse pedicle diameter of the cervical spine in a Malaysian population, and evaluate the feasibility and safety of pedicle screw fixation in these patients.

Summary Of Background Data: Cervical transpedicular screw fixation has been safe and is most probably going to be the gold standard for cervical spine fixation. However, its use in the Asian population should be considered cautiously because our cervical pedicle diameter may not be adequate to accommodate the standard pedicle screw size, which can be dangerous because there are vital structures located adjacent to the pedicles.

Methods: The measurements of the cervical pedicles were performed on CT images using its measurement tools. CT cutting was made at 2.5-mm intervals. The pedicle transverse diameters were defined as the most outer diameter of the pedicle, taken perpendicular to the axis of the pedicle and measured in millimeters up to 0.1 mm.

Results: The mean transverse diameters of the cervical pedicle of C2, C3, C4, C5, C6, and C7 in males were 5.4, 5.2, 5.1, 5.2, 5.5, and 6.5 mm, respectively, and ranged between 5.1 and 6.5 mm. In females, the mean transverse diameter of the cervical pedicle of C2, C3, C4, C5, C6, and C7 were 5.0, 4.6, 4.7, 4.9, 5.2, and 5.6 mm, respectively, and ranged between 4.6 and 5.6 mm. If the minimum transverse diameter required is 5.0 mm for 3.5-mm screw insertion, about 4.2% to 54.2% (male) of pedicles at different levels and 6.7% to 73.3% (females) of patients cannot have fixation with a 3.5-mm screw using this technique.

Conclusion: Transpedicular screw fixation for the cervical spine must not be attempted in the Malaysian population before the exact pedicle diameters are known.Therefore, preoperative CT evaluation is a must before transpedicular fixation is performed, especially in female patients. Because the margin for mistake is very narrow, it is best avoided in upper cervical spines.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/01.brs.0000210263.87578.65DOI Listing
April 2006

Actinomycosis of the knee.

Malays J Med Sci 2005 Jan;12(1):68-9

Department of Orthopaedics.

We report a case of actinomycosis presenting as a knee swelling in a 34 year-old man. Knee actinomycosis poses a diagnosis challenge to clinicians as it is rare, often mimics knee tuberculosis and culture of the causative microbes is technically difficult. The classic microscopic appearance of this Gram-positive bacteria often forms the basis of diagnosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3349416PMC
January 2005
-->