Mohd Imran Yusof

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

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.

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

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 Students 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° 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.

The Outcomes of Salvage Surgery for Vascular Injury in The Extremities: A Special Consideration For Delayed Revascularization

Abstract A seven years retrospective study was performed in 45 consecutive vascular injuries in the extremities to investigate the pattern of injuries, managements and outcomes. Motor-vehicle accidents were the leading cause of injuries (80%), followed by industrial injuries (11.1%) and iatrogenic injuries (4.4%). Popliteal and brachial artery injuries were commonly involved (20%). Fifteen (33.3%) patients had fractures, dislocation or fracture dislocation around the knee joint and 6 (13.3%) patients had soft tissue injuries without fracture. Traumatic arterial transection accounted for 34 (75.6%) cases, followed by laceration in 7 (15.6%) and 9 (6.7%) contusions. Associated nerve injuries were seen in 8 (17.8 %) patients using intra-operative findings as the gold standard, both conventional angiogram (CA) and computerized tomography angiogram (CTA) had 100% specificity and 100% sensitivity in determining the site of arterial injuries. The mean ischemic time was 25.31 hours (4 - 278 hours). Thirty-three (73.3 %) patients were treated more than 6 hours after injury and 6 patients underwent revascularization after 24 hours; all had good collateral circulation without distal pulses or evidence of ischemic neurological deficit. The mean ischemic time in 39 patients who underwent revascularization within 24 hours was 13.2 hours. Delayed amputation was performed in 5 patients (11.1%). Of the 6 patients who underwent delayed revascularization, one patient had early amputation, one -had delayed amputation following infection and multiple flap procedures while the rest of the patients’ limbs survived. Joint stiffness was noted in 10 patients (22.2%) involving the knee joint, elbow and shoulder in two patients each. Infection was also noted in 5 patients (11.1%) with two of them were due to infected implants. Other complications encountered included nonunion (2 patients, 4.4%), delayed union (1 patient, 2.2%),limb length discrepancy (1 patient, 2.2%), hematoma (1 patient, 2.2%) and leaking anastomosis in one patient (2.2%). Volkmann’s ischemic contracture occurred in 3 (6.7%) patients. There was no complication noted in 8 (17.8%) patients Three patients (6.7%) died of whom two were not due to vascular causes. We conclude that early detection and revascularization of traumatic vascular injuries is important but delayed revascularization also produced acceptable results.

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

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

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

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.

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

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.

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

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.

Utilization of the Acoustic Emission Technology in Bone Tissues

The main subject of this study was to establish a meaningful significance of the acoustic emission technology to be incorporated in the pedicle screw fixation procedure. Its purpose was to find a replacement technique using the acoustic emission technology instead of keep using the conventional way which only depends on the surgeons expertise. The experiment of pedicle screw fixation method work was carried out on a goats vertebrae as a lab scale material instead of the human cervical vertebrae. While the experimental work was done, the acoustic emission signatures were then acquired using the Physical Acoustics acoustic emission data acquisition system. Once completed, the acoustic emission signatures were then analysed using Matlab software together with the AEWin software package. From the results obtained, the numbers of data counts are generally bigger for the pedicle screw fixation procedure at early stage of bone penetration compared to the latter. It is significant to the different structure of bones as hard bone technically takes more time to be penetrated compared to the soft ones. This technique undoubtedly has high potential to be studied further so that it can be commercialized into the medical field.

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

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 (p>0.05). In addition, no significant difference was found in the vGRF measurements of all the joints among the three groups (p>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.

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

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.