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Biomedical subjects

T H Lim

Publications and source records attributed to T H Lim.

At least 37 records · Page 2Linked to original sources
PubMed2001

A biomechanical comparison of modern anterior and posterior plate fixation of the cervical spine.

STUDY DESIGN: A biomechanical study was designed to assess relative rigidity provided by anterior, posterior, or combined cervical fixation using cadaveric cervical spine models for flexion-distraction injury and burst fracture. OBJECTIVES: To compare the construct stability provided by anterior plating with locked fixation screws, posterior plating with lateral mass screws, and combined anterior-posterior fixation in clinically simulated 3-column injury or corpectomy models. SUMMARY OF BACKGROUND DATA: Anterior plating with locked fixation screws is the most recent design and is found to provide better stability than the conventional unlocked anterior plating. However, there are few data on the direct comparison of biomechanical stability provided by anterior plating with locked fixation screws versus posterior plating with lateral mass screws. Biomechanical advantages of using combined anterior-posterior fixation compared with that of using either anterior or posterior fixation alone also have not been well investigated yet. METHODS: Biomechanical flexibility tests were performed using cervical spines (C2-T1) obtained from 10 fresh human cadavers. In group I (5 specimens), one-level, 3-column injury was created at C4-C5 by removing the ligamentum flavum and bilateral facet capsules, the posterior longitudinal ligament, and the posterior half of the intervertebral disc. In group II (5 specimens), complete corpectomy of C5 was performed to simulate burst injury. In each specimen, the intact spine underwent flexibility tests, and the following constructs were tested: (1) posterior lateral mass screw fixation (Axis plate) after injury; (2) polymethylmethacrylate anterior fusion block plus posterior fixation; (3) polymethylmethacrylate block plus anterior (Orion plate) and posterior plate fixation; and (4) polymethylmethacrylate block plus anterior fixation. Rotational angles of the C4-C5 (or C4-C6) segment were measured and normalized by the corresponding angles of the intact specimen to study the overall stabilizing effects. RESULTS: Posterior plating with an interbody graft showed effective stabilization of the unstable cervical segments in all loading modes in all cases. There was no significant stability improvement by the use of combined fixation compared with the posterior fixation with interbody grafting, although combined anterior-posterior fixation tended to provide greater stability than both anterior and posterior fixation alone. Anterior fixation alone was found to fail in stabilizing the cervical spine, particularly in the flexion-distraction injury model in which no contribution of posterior ligaments is available. Anterior plating fixation provided much greater fixation in the corpectomy model than in the flexion-distraction injury model. This finding suggests that preservation of the posterior ligaments may be an important factor in anterior plating fixation. CONCLUSIONS: This study showed that the posterior plating with interbody grafting is biomechanically superior to anterior plating with locked fixation screws for stabilizing the one-level flexion-distraction injury or burst injury. More rigid postoperative external orthoses should be considered if the anterior plating is used alone for the treatment of unstable cervical injuries. It was also found that combined anterior and posterior fixation may not improve the stability significantly as compared with posterior grafting with lateral mass screws and interbody grafting.

Aged↗
PubMed2001

Different clinical features of aortic intramural hematoma versus dissection involving the ascending aorta.

OBJECTIVES: The goal of this study was to test the hypothesis that the absence of direct flow communication through intimal tear in aortic intramural hematoma (AIH) involving the ascending aorta has different clinical impact on clinical course compared with typical aortic dissection (AD). BACKGROUND: Although emergent surgical repair has been applied for patients with proximal AIH as if it was typical AD, the natural history of proximal AIH is not known clearly yet. METHODS: Direct comparison of the clinical data of 81 patients with proximal AD and 24 patients with AIH was performed retrospectively. RESULTS: Patients with AIH were older (67 +/- 10 vs. 50 +/- 13, p = 0.001), and female gender was more predominant in AIH (19/24 vs. 29/81, p = 0.001). The development of mediastinal hemorrhage and pericardial and pleural effusion was more frequent in patients with AIH than it was in patients with AD. Although medical treatment was more frequently selected in the AIH group (75% vs. 15%, p = 0.001) due to old age and other associated medical diseases, the mortality rate with medical treatment was much lower in patients with AIH than it was in patients with AD (6% vs. 58%, p = 0.003). In follow-up imaging studies of 13 patients who survived AIH without surgical repair, seven patients showed complete resolution. Typical AD developed in three patients, and the other three patients showed focal AD only in the descending aorta. The two-year survival rate did not show significant difference (84% +/- 6% in AIH vs. 76% +/- 17% in AD, p = 0.47). CONCLUSIONS: Absence of continuous flow communication can explain a more favorable clinical course of AIH than for AD, and medical treatment with frequent imaging follow-up and timed elective surgery in cases with complications can be a rational option for patients with proximal AIH.

Age Distribution↗
PubMed2001

Orientation and osteoarthritis of the lumbar facet joint.

Several studies have shown an association between sagittal orientation of the facet joint and degenerative spondylolisthesis. There is currently no information available on the association between orientation of the facet joint and osteoarthritis. This study examined the association between orientation and osteoarthritis of the lumbar facet joints. One hundred eleven consecutive patients underwent plain radiography and magnetic resonance imaging. These patients were divided into two groups: No Degenerative Spondylolisthesis Group (98 patients) and Degenerative Spondylolisthesis Group (13 patients). In the No Degenerative Spondylolisthesis Group, segments with higher grades of osteoarthritis showed more sagittal orientation of the facetjoints at the L3-L4 and L4-L5 levels. The facet joint was oriented significantly more sagittally in the Degenerative Spondylolisthesis Group than in the No Degenerative Spondylolisthesis Group at the L4-L5 and L5-S1 levels. The severity of facet joint osteoarthritis was significantly higher in the Degenerative Spondylolisthesis Group than in the No Degenerative Spondylolisthesis Group at the L3-L4, L4-L5, and L5-S1 levels. A significant association was found between sagittal orientation and osteoarthritis of the lumbar facet joints, even in patients without degenerative spondylolisthesis. Facet joint osteoarthritis, rather than spondylolisthesis, is the pathoanatomic feature that is associated with sagittal orientation of the facet joints in patients with degenerative spondylolisthesis.

Aged↗
PubMed2001

Does education explain ethnic differences in myopia prevalence? A population-based study of young adult males in Singapore.

PURPOSE: To study interethnic variation in myopia prevalence and severity in young adult males in Singapore and to determine whether these variations are related to differences in education level. METHODS: A population-based survey of refractive errors in a cohort of 15,095 military conscripts between July 1996 and June 1997 using noncycloplegic autorefraction and a standard questionnaire. Prevalence rates of myopia (<-0.5 D) and severe myopia (<-6.0 D) were determined for Chinese, Malay, and Indian men; prevalence rate ratios were compared after adjusting for education level. RESULTS: Singapore has one of the highest prevalences of myopia (79.3%) and severe myopia (13.1%), with Chinese having higher rates (82.2%, 95% confidence interval 81.5, 82.9) compared with Indians (68.7%, 95% confidence interval 65.1, 67.1) and Malays (65.0%, 95% confidence interval 62.9, 67.1). Education was strongly associated with prevalence and severity of myopia. However, significant interethnic variation persisted after adjusting for education. CONCLUSIONS: There is a high prevalence of myopia in Singapore. Although prevalence and severity of myopia were strongly associated with education, interethnic variation observed was not fully explained by differences in education level.

Adolescent↗
PubMed2001

Occlusive myocardial infarction: investigation of bis-gadolinium mesoporphyrins-enhanced T1-weighted MR imaging in a cat model.

PURPOSE: To test whether bis-gadolinium mesoporphyrins-enhanced magnetic resonance (MR) imaging can accurately depict irreversibly damaged myocardium in occlusive myocardial infarction. MATERIALS AND METHODS: Ten cats were subjected to 90 minutes of occlusion of the left anterior descending coronary artery. Bis-gadolinium mesoporphyrins-enhanced T1-weighted MR imaging was performed in the cats for 6 hours. Histopathologic examinations with 2'3'5-triphenyl tetrazolium chloride (TTC) staining and electron microscopy were performed on the resected specimens. The time course and pattern of signal intensity enhancement were evaluated. The size of the infarcted myocardium was estimated on the MR images by measuring the size of the signal intensity-enhanced area. RESULTS: In eight of 10 cats, it was impossible to distinguish infarcted myocardium from normal myocardium at visual inspection of T1-weighted MR images. The contrast ratio between infarcted and normal myocardium did not increase significantly over time. In one of the two remaining cats, a doughnut pattern of signal intensity enhancement was noted. The other cat showed intensely homogeneous enhancement of infarcted myocardium at MR imaging. The size of the area of signal intensity enhancement at MR imaging in these two cats was accurately mapped to that of the infarction on the TTC-stained specimens. CONCLUSION: Occlusive myocardial infarction cannot be accurately detected at bis-gadolinium mesoporphyrins-enhanced MR imaging.

Animals↗
PubMed2001

Cerebral metabolic abnormalities in COPD patients detected by localized proton magnetic resonance spectroscopy.

STUDY OBJECTIVES: To investigate changes in the cerebral metabolism of patients with COPD, using localized in vivo proton magnetic resonance spectroscopy ((1)H MRS), and to evaluate the clinical significance of cerebral metabolic abnormalities in COPD patients. PATIENTS AND METHODS: Seventeen symptomatic COPD patients and 21 age-matched healthy volunteers participated in this study. All subjects underwent (1)H MRS, and neuropsychological tests (Wechsler memory scale-revised [WMS-R], color trail test, and grooved pegboard test) were performed by COPD patients. Magnetic resonance spectra were obtained from localized regions of parietal white matter (PWM) and occipital gray matter (OGM). Absolute levels of N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), and myo-inositol (mI) were calculated. RESULTS: In COPD patients, the mean (+/- SD) FEV(1) was 38 +/- 10% predicted, the PaCO(2) was 39 +/- 7 mm Hg, and the PaO(2) was 89 +/- 18 mm Hg, and these values did not exhibit statistical correlation with the levels of cerebral metabolites. NAA, Cr, and Cho levels in PWM were all significantly lower in COPD patients than in control subjects (p < 0.0125 [Bonferroni adjusted]). Neuropsychological parameters were lower in COPD patients compared with standardized values. However, they were not correlated with the levels of cerebral metabolites except for a positive correlation between the Cho level in PWM and the general memory quotient of WMS-R (r = 0.52; p < 0.05). CONCLUSIONS: Our results demonstrate that the cerebral metabolism is significantly altered in symptomatic COPD patients. The relationship between decreased Cho levels and memory dysfunction, and the clinical significance of other cerebral metabolic changes in COPD patients need to be further investigated.

Aged↗
PubMed2001

Viable myocardium in reperfused acute myocardial infarction: rest and stress first-pass mr imaging.

Feasibility of identifying viable myocardium in rest and stress magnetic resonance imaging (MRI) was evaluated using 3 hr occlusion and 30 min reperfusion model of left anterior descending (LAD) coronary artery in 12 felines. At rest MRI, viable myocardium confirmed by 2,3,5-triphenyl tetrazolium chloride (TTC)-staining showed rapid signal intensity (SI) rise followed by gradual decline not significantly different from normal myocardium that the two hyperperfused regions were distinguishable only from the hypoperfused nonviable myocardium. At stress MRI, hyperemia induced perfusion change was most pronounced in normal myocardium with earlier and greater peak enhancement followed by brisk 'washout' phase while minimally augmented enhancement in viable myocardium was still in 'washin' phase. From these findings, it was concluded that viable myocardium is identified in rest and stress MRI as redistributing hypo- perfusion compared to persistent hyper-perfusion of the normal myocardium and the persistent hypo-perfusion of the nonviable myocardium.

Animals↗
PubMed2001

Relationship between gestational age and frequency of fetal trophoblasts and nucleated erythrocytes in maternal peripheral blood.

The relationship between gestational age and frequency of fetal cells in the maternal blood was studied in order to determine the optimal time for cell recovery. The immunomagnetic colloid system was used to enrich nucleated erythrocytes (NRBCs) and trophoblasts from 20 ml maternal blood samples obtained between 9 and 35 weeks' gestation (n=41). Nested polymerase chain reaction (PCR) for the Y chromosome of enriched NRBCs and trophoblasts showed decreasing negative predictive values with increasing gestational age. The sensitivity and the overall frequency for correct fetal gender diagnosis were the lowest in the third trimester. Fluorescence in situ hybridisation (FISH) using XY DNA-specific probes was used to determine the fetal gender of the trophoblast-enriched fraction. The fetal origin of enriched NRBCs was determined using simultaneous immunophenotyping for fetal hemoglobin and FISH with XY probes. The mean number and mean percentage purity for both fetal trophoblasts and NRBCs showed decreasing values with increasing gestational age. However, statistical analysis showed no relationship between gestational age and frequency of fetal cells even though more fetal cells tend to exist during the first trimester. Nevertheless, the first trimester appears to offer the most optimal time for fetal cell recovery from maternal blood for the purpose of prenatal diagnosis.

Blood Cells↗
PubMed2000

The effect of disc degeneration and facet joint osteoarthritis on the segmental flexibility of the lumbar spine.

STUDY DESIGN: A biomechanical and imaging study of human cadaveric spinal motion segments. OBJECTIVE: To investigate the effect of both disc degeneration and facet joint osteoarthritis on lumbar segmental motion. SUMMARY OF BACKGROUND DATA: Spinal degeneration includes the osteoarthritic changes of the facet joint as well as disc degeneration. Disc degeneration has been reported to be associated with spinal motion. The association of facet joint osteoarthritis with lumbar segmental motion characteristics and the combined influence of disc degeneration and facet osteoarthritis has not yet been investigated. METHODS: A total of 110 lumbar motion segments (52 female, 58 male) from 44 human lumbar spines were studied (mean age = 69 years). Magnetic resonance images were used to assess the disc degeneration from Grade I (normal) to Grade V (advanced) and the osteoarthritic changes in the facet joints in terms of cartilage degeneration, subchondral sclerosis, and osteophytes. Disc height, endplate size, and facet joint orientation and width also were measured from the computed tomographic images. Rotational movements of the motion segment in response to the flexion, extension, lateral bending, and axial rotational moments were measured using a three-dimensional motion analysis system. RESULTS: Female motion segments showed significantly greater motion (lateral bending: P < 0. 001, flexion: P < 0.01, extension: P < 0.05) and smaller endplate size (P < 0.001) than male ones. The segmental motion increased with increasing severity of disc degeneration up to Grade IV, but decreased in both genders when the disc degeneration advanced to Grade V. In male segments, the disc degeneration-related motion changes were significant in axial rotation (P < 0.001), lateral bending (P < 0.05), and flexion (P < 0.05), whereas female segments showed significant changes only in axial rotation (P < 0.001). With cartilage degeneration of the facet joints, the axial rotational motion increased, whereas the lateral bending and flexion motion decreased in female segments. In male segments, however, motion in all directions increased with Grade 3 cartilage degeneration and decreased with Grade 4 cartilage degeneration. Subchondral sclerosis significantly decreased the motion (female: axial rotation, P < 0. 05; extension, P < 0.05 vs.- male:flexion,P < 0.05). Severity of osteophytes had no significant association with the segmental motion. CONCLUSION: Axial rotational motion was most affected by disc degeneration, and the effects of disc degeneration on the motion were similar between genders. Facet joint osteoarthritis also affected segmental motion, and the influence differed for male and female spines. Further studies are needed to clarify whether the degenerative process of facet joint osteoarthritis differs between genders and how facet joint osteoarthritis affects the stability of the spinal motion segment.

Cadaver↗
PubMed2000

Laser pointers and the human eye: a clinicopathologic study.

We report the absence of photic retinal injury after exposing the retina to light from class 3A laser pointers for durations of up to 15 minutes. Three patients with uveal melanomas were scheduled to have an enucleation. Each agreed to have his or her retina exposed to laser light from a class 3A laser pointer prior to enucleation. Continuous exposure was directed to the fovea for 1 minute, to the retina 5 degrees below fixation for 5 minutes, and to the retina 5 degrees above fixation for 15 minutes. Ophthalmoscopic evaluation of the cornea, lens, and retina and fluorescein angiographic studies of the retina were conducted before, 24 hours after, and 11 days after laser exposure in the first case; before and 86 hours after exposure in the second case; and before, 96 hours after, and 15 days after exposure in the third case. Other than transient afterimages that lasted only a few minutes, we were unable to document any functional, ophthalmoscopic, fluorescein angiographic, or histologic evidence of damage to any structures of the eyes. Transmission electron microscopic studies of retinal sites targeted by the laser pointers in the second and third cases revealed ultrastructural abnormalities in the outer retina and the pigment epithelium that were similar to abnormalities seen in the retina approximately 8 mm away from the targeted sites. The risk to the human eye from transient exposure to light from commercially available class 3A laser pointers having powers of 1, 2, and 5 mW seems negligible.

Adult↗
PubMed2000

Application of breath-hold T2-weighted, first-pass perfusion and gadolinium-enhanced T1-weighted MR imaging for assessment of myocardial viability in a pig model.

The purpose of this study was to correlate the abnormal signal area on various magnetic resonance (MR) images to the infarct area on pathologic examination and to assess the myocardial viability on the basis of MR images. T2-weighted, first-pass perfusion, and delayed gadolinium-enhanced T1-weighted images were used as "one-stop examinations" in a pig model of reperfused myocardial infarction. The results of each MR image were compared with those of 2,3, 5-triphenyltetrazolium chloride (TTC) staining. The abnormal signal areas on T2-weighted and Gd-enhanced T1-weighted images were larger than the infarct areas on TTC staining (34.7% and 32.3% vs. 28.3%; P< 0.05), whereas the nonperfused areas on perfusion images were correlated (25.6% vs, 28.3%; P = 0.139). Electron microscopic examination showed severely distorted ultrastructures in the infarct areas and mildly damaged ultrastructures in the peri-infarct areas. Perfusion images probably reflected the infarct areas, whereas T2-weighted and Gd-enhanced T1-weighted images seemed to include peri-infarct as well as infarct areas.

Animals↗
PubMed2000

Poroelastic properties of bovine vertebral trabecular bone.

The theory of poroelasticity has been used to study bone mechanics without directly measuring poroelastic properties. In this study, we developed an experimental protocol and measured the poroelastic properties of bovine vertebral trabecular bone. Mean (+/-SD) values for drained shear modulus, drained Poisson's ratio, undrained Poisson's ratio, Skempton's coefficient, and permeability coefficient were, respectively, 90.85 (+/-59.59) MPa and 0.242 (+/-0.099), 0.399 (+/-0.083), 0.851 (+/-0.144), and 16.31 (+/-8.02) x 10(-8) m2/Pa/sec, respectively. The experimental protocol can be used generally for the measurement of poroelastic properties of bone when cylindrical specimens are available. Measured poroelastic properties can be used directly or converted to Biot's coefficient and modulus, without assuming the incompressibility of solid and fluid constituents, for the poroelastic modeling of bone.

Animals↗
PubMed2000

Subjective visual experience during phacoemulsification and intraocular lens implantation under topical anesthesia.

OBJECTIVE: The aim of this study was to investigate the subjective visual experience of patients during phacoemulsification and intraocular lens (IOL) implantation under topical anesthesia. DESIGN: Postoperative questionnaire survey. PARTICIPANTS: The study cohort consisted of 52 patients with cataracts. There were 18 male (34.6%) and 34 female (65.4%) patients. Their mean (+/- SD) age was 67.5 (+/-10.8) years. INTERVENTION: The patients underwent routine phacoemulsification and IOL implantation under topical anesthesia. MAIN OUTCOME MEASURES: The patients were interviewed on the same day after their operation regarding their visual experience in the operated eye during surgery. RESULTS: All patients (100%) reported that they could see at least some light during the surgery. Some patients reported they could also see one or more colors (50 patients, 96.2%), movements (32 patients, 61.5%), flashes (24 patients, 46.2%), the surgeon's fingers/hands (13 patients, 25%), instruments (12 patients, 23.1%), and/or the surgeon (4 patients, 7.7%). The colors seen included red (24 patients, 46.2%), yellow (23 patients, 44.2%), blue (12 patients, 23.1%), green (7 patients, 13.5%), and orange (6 patients, 11.5%). Eight patients (15.4%) saw the spectrum of colors similar to that of the rainbow. Twenty-four patients (46.2%) reported that the brightness of light changed during the course of the operation. Eight patients (15.4%) found their visual experience frightening. There was no statistically significant association between those who found the visual experience frightening and the sex or age of the patient, a history of cataract operation in the fellow eye, the type of visual sensation experienced, or the presence of coexisting ocular pathology. CONCLUSION: All patients undergoing phacoemulsification under topical anesthesia experience a variety of visual sensations that may be frightening in a small proportion of patients.

Aged↗
PubMed2000

Subjective visual experience during phacoemulsification and intraocular lens implantation using retrobulbar anesthesia.

PURPOSE: To investigate the subjective visual experience of patients during phacoemulsification and intraocular lens (IOL) implantation using retrobulbar anesthesia. SETTING: Department of Ophthalmology, Tan Tock Seng Hospital, Singapore. METHODS: Seventy cataract patients who had routine phacoemulsification and posterior chamber IOL implantation under retrobulbar anesthesia were interviewed on the day of their surgery regarding their visual experience in the operated eye during surgery. Thirty-nine men (55.7%) and 31 women (44.3%) were included in the study. Their mean age was 65.1 years (range 37 to 87 years). Preoperative best corrected visual acuity ranged from 6/12 to counting fingers. Sixty eyes (85.7%) had no ocular pathology other than cataract. Eleven patients (15.7%) reported no light perception during the surgery. The rest reported they could see light (59 patients, 84.3%), 1 or more colors (39 patients, 55.7%), flashes (35 patients, 50.0%), movements (34 patients, 48.6%), instruments (12 patients, 17.1%), and the surgeon's fingers or hands (11 patients, 15.7%). The colors seen included red (23 patients, 32.9%), blue (17 patients, 24.3%), yellow (12 patients, 17.1%), green (7 patients, 10. 0%), and orange (1 patient, 1.4%). Eight patients (11.4%) saw a spectrum of colors similar to a rainbow. Thirty-one patients (44.3%) reported that the brightness of light changed during surgery. Five patients (7.1%) found their visual experience frightening. Patients who reported seeing colors (P =.048, Fisher exact test) and flashes of light (P =.027, Fisher exact test) were more likely to find the experience frightening. There was no statistically significant correlation between those who found the experience frightening and patient sex or age, length of surgery, or history of cataract surgery in the fellow eye. CONCLUSIONS: Many patients having phacoemulsification and IOL implantation under retrobulbar anesthesia experienced a variety of visual sensations that were frightening in a small proportion of cases.

Adult↗
PubMed2000

Central serous retinopathy complicating systemic lupus erythematosus: a case series.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder with widespread manifestations including the eye. Central serous retinopathy (CSR) has been associated as a complicating event in SLE, although it is uncommon. We present a case series of four female Chinese SLE patients who developed CSR during the course of their systemic disease. All four presented clinically with typical CSR. Angiographic findings did not show evidence of choroidal ischaemia or delayed choroidal filling. Resolution of the serous retinal detachment occurred in all four patients. Recovery of vision was seen in three patients. The clinical outcome was similar to that occurring in the usual male population. Central serous retinopathy as a manifestation of SLE may be caused by various factors. These include SLE-associated choroidopathy, systemic hypertension, renal disease, retinal pigment epithelial dysfunction and glucocorticoid therapy.

Adult↗
PubMed2000

Biomechanical effect of anterior grafting devices on the rotational stability of spinal constructs.

In the thoracolumbar spine, frequently strut grafting is used to restore the anterior and middle column defects. Biomechanical stability of the surgical construct may be altered significantly depending on the type of anterior grafting devices. In this study, a biomechanical flexibility test was conducted to compare the stabilizing role of various types of anterior grafting devices, such as a polymethylmethacrylate block, tricortical iliac crest bone graft, one large Harms cage, and two small Harms cages using a calf lumbar corpectomy model. The Harms cage, especially one large cage, improved the axial rotational stability significantly in both anterior and posterior fixation groups as compared with the iliac bone or polymethylmethacrylate. No significant difference in the stabilizing role was found among different grafting devices in lateral bending, flexion, and extension. These results suggest that a more rigid spinal construct can be obtained by using a metal cage with improved friction at the cage-bone interface.

Animals↗
PubMed2000

The relationship between disc degeneration, facet joint osteoarthritis, and stability of the degenerative lumbar spine.

Degenerative processes in the disc and facet joints affect the stability of the motion segment. The exact relations among disc degeneration, facet joint osteoarthritis, and the kinematics of the motion segment are not well defined in the literature. Magnetic resonance imaging and functional radiography of the lumbar spine were analyzed to examine the relations among segmental instability, facet joint osteoarthritis, and disc degeneration in patients with degenerative disorders of the lumbar spine. Seventy consecutive patients (mean age, 46 years) had both magnetic resonance imaging and flexion and extension radiographs of the lumbar spine. The lumbar instability was classified into abnormal tilting on flexion, rotatory instability in the sagittal plane, and translatory instability. Translatory instability was subdivided into anterior, posterior, and anteroposterior translatory instability. Disc degeneration as seen on T2-weighted sagittal images was classified into five grades. Facet joint osteoarthritis as seen on axial T1-weighted images was divided into four grades. This study revealed that the kinematics of the lumbar motion segment are affected by disc degeneration and facet joint osteoarthritis. Abnormal tilting movement on flexion and anteroposterior translatory instability both had negative associations with facet joint osteoarthritis. However, anterior translatory instability was positively associated with disc degeneration and facet joint osteoarthritis. Rotatory instability in the sagittal plane and posterior translatory instability were not associated with disc degeneration and facet joint osteoarthritis.

Adolescent↗