Precise length definition of active GaAs-based optoelectronic devices for low-loss silicon photonics integration.

The length variation associated with standard cleaving of III-V optoelectronic chips is a major source of loss in the integration with the micron-scale silicon-on-insulator waveguides. To this end, a new, to the best of our knowledge, approach for precise definition of the III-V chip length is reported. The method employs lithography and wet etching of cleave marks outside the active III-V waveguides. The marks follow a specific crystallographic orientation and are used to initiate and guide the cleaving process. Besides minimizing the air gap between the butt-coupled III-V and Si waveguides and hence minimizing the coupling losses, the use of precisely defined length significantly improves the integration yield owing to the increased length uniformity. We apply this technique to defining the lengths of GaAs-based semiconductor optical amplifiers and demonstrate length control with an accuracy better than 250 nm per facet. This variation is more than 1 order of magnitude smaller than with the traditional cleaving methods, resulting in improvement of coupling by several dBs.

Preoperative Predictors of Better Long-term Functional Ability and Decreased Pain Following LSS Surgery: A Prospective Observational Study with a 10-year Follow-up Period.

STUDY DESIGN: A prospective observational 10-year follow-up study. OBJECTIVE: This study aimed to examine preoperative predictors for better surgical outcomes in patients with lumbar spinal stenosis (LSS) 10 years after surgery. SUMMARY OF BACKGROUND DATA: LSS is a leading cause of low back surgery in patients older than 65 years. Limited data are available for predictors of long-term surgical outcomes in patients with LSS. METHODS: At the baseline, 102 patients with LSS underwent decompressive surgery, and 72 of the original study sample participated in a 10-year follow-up study. Study patients filled out a questionnaire preoperatively, and follow-up data were collected at 3 months, 6 months, 1 year, 2 years, 5 years, and 10 years postoperatively. Surgical outcomes were evaluated in terms of disability with the Oswestry Disability Index (ODI) and pain with the visual analog scale (VAS). Predictors in the models were nonsmoking status, absence of previous lumbar surgery, self-rated health, regular use of painkillers for symptom alleviation, and BMI. Statistical analyses included longitudinal associations, subgroup analyses, and cross-sectional analyses. RESULTS: Using multivariate analysis, statistically significant predictors for lower ODI and VAS scores at 10 years were nonsmoking status, absence of previous lumbar surgery, better self-rated health, and regular use of painkillers for <12 months. Patients who smoked preoperatively or had previous lumbar surgery experienced more pain and disability at the 10-year follow-up. CONCLUSION: These study results can enhance informed decision-making processes for patients considering surgical treatment for LSS by showing preoperative predictors for surgical outcomes up to 10 years after surgery. Smokers and patients with previous lumbar surgery showed a decline in surgical benefits after 5 years. LEVEL OF EVIDENCE: 3.

Preoperative sense of coherence associated with the 10-year outcomes of lumbar spinal stenosis surgery.

A prospective 10-year follow-up study was conducted to determine the significance of the preoperative sense of coherence, with respect to the preoperative and 10-year clinical characteristics, among lumbar spinal stenosis patients ( N = 99). In addition, the predictive value of the preoperative sense of coherence regarding the 10-year surgery outcome was also evaluated. In a logistic regression analysis, a weak preoperative sense of coherence and low functional ability predicted the patients' functional ability 10 years after the surgery. Moreover, those patients with weak sense of coherence before surgery showed poorer functional ability 10 years after the surgery, but not preoperatively. A weak preoperative sense of coherence seems to associate with poorer long-term outcome after surgery; therefore, various rehabilitation strategies are discussed.

Depression is associated with the long-term outcome of lumbar spinal stenosis surgery: a 10-year follow-up study.

BACKGROUND CONTEXT: Depression is associated with greater postoperative disability in patients with lumbar spinal stenosis (LSS). No previous studies have reported the association in a 10-year follow-up. PURPOSE: To evaluate the association between preoperative and postoperative depressive symptoms and the surgical outcome among patients with LSS in a 10-year follow-up. In addition, we examined the effects of the depressive burden on the surgical outcome. DESIGN: A prospective observational follow-up study. PATIENT SAMPLE: A total of 102 patients with LSS underwent decompressive surgery, and 72 of the original sample participated in the 10-year follow-up study. OUTCOME MEASURES: Self-report measures: the Oswestry Disability Index (ODI) and visual analog scale (VAS). METHODS: Data were collected using a questionnaire that was administered seven times during the study period. Depressive symptoms were measured with the Beck Depressive Inventory (BDI). The depressive burden was calculated by summing the preoperative and all follow-up BDI scores. Statistical analysis included cross-sectional group comparisons and linear mixed models. The authors report no conflicts of interest related to this work. RESULTS: The high depressive burden group had a poorer outcome for pain, disability, and the walking distance at the 10-year follow-up. In linear mixed models, a higher preoperative BDI score associated with higher disability. Furthermore, higher postoperative BDI scores and the depressive burden were associated with higher disability and pain in the 10-year follow-up. CONCLUSIONS: Patients with LSS with even slightly elevated depressive symptoms have an increased risk of postoperative pain and disability in a 10-year follow-up. To improve the surgical outcome among these patients, screening for depression both preoperatively and during the rehabilitation following surgery is important.

Data transmission at 1300 nm using optical interposer comprising hybrid integrated silicon waveguide and dilute nitride electroabsorption modulator.

High speed back-to-back transmission of NRZ data at 12.5 Gbit/s was achieved over a repeaterless optical network without the use of forward error correction or optical clock recovery using a hybrid integrated silicon photonics optical interconnect. The interconnect comprises an electroabsorption modulator based on dilute nitride multiple quantum well material on GaAs substrate optically coupled to large core silicon waveguide using passive alignment and flip-chip bonding.

Low sense of coherence during postoperative recovery is associated with a poorer lumbar spinal stenosis - surgical outcome: A 5-year follow-up study.

This study investigated the association between the 3-month postoperative sense of coherence and the 5-year postoperative outcome of decompressive surgery for lumbar spinal stenosis. The participants with a lower sense of coherence at the 3-month follow-up had a poorer functional ability and lower satisfaction with surgery, higher pain ratings, lower life satisfaction and more depressive symptoms 5 years postoperatively. A low 3-month sense of coherence associated with greater pain and a poorer functional ability 5 years postoperatively. Evaluating sense of coherence and depressive symptoms in patients who have had lumbar spinal stenosis surgery may help in identifying those in need of enhanced support for postoperative recovery.

Life dissatisfaction is associated with depression and poorer surgical outcomes among lumbar spinal stenosis patients: a 10-year follow-up study.

Life satisfaction is associated with overall somatic health and the short-term surgical outcome in lumbar spinal stenosis (LSS) patients. In this study, the long-term relationship between life satisfaction and the surgical outcome in LSS patients was investigated in a 10-year follow-up. This prospective clinical study included 102 LSS patients who underwent decompressive surgery. They completed a set of questionnaires first preoperatively and then 6 times postoperatively (at 3 and 6 months, and at 1, 2, 5 and 10 years). The final study population at the 10-year follow-up comprised 72 patients. A four-item life satisfaction scale was used to measure global life satisfaction. The sum of all seven life satisfaction scores provided a measure of the life dissatisfaction burden over the entire 10-year follow-up. Depression was measured using the Beck Depression Inventory. The surgical outcome was evaluated using the Oswestry Disability Index, pain evaluation (visual analogue scale), self-reported walking capacity and overall satisfaction with the surgery. Both preoperative life dissatisfaction and the long-term life dissatisfaction burden were associated with poorer 10-year surgical outcomes (i.e. Oswestry Disability Index and visual analogue scale) in logistic regression analyses. Life dissatisfaction was also associated with symptoms of depression. Monitoring subjective well-being, especially life satisfaction and mood, in LSS patients before and after surgery may help in detecting those at risk of a poorer long-term surgical outcome.

The effect of decompressive surgery on lumbar paraspinal and biceps brachii muscle function and movement perception in lumbar spinal stenosis: a 2-year follow-up.

PURPOSE: Chronic low back pain and lumbar spinal stenosis (LSS) seem to deteriorate lumbar muscle function and proprioception but the effect of surgery on them remains unclear. This study evaluates the effect of decompressive surgery on lumbar movement perception and paraspinal and biceps brachii (BB) muscle responses during sudden upper limb loading in LSS. METHODS: Low back and radicular pain intensity (VAS) and Oswestry Disability Index (ODI) were measured together with lumbar proprioception and paraspinal and BB muscle responses prior to and 3 and 24 months after surgery in 30 LSS patients. Lumbar proprioception was assessed by a previously validated motorized trunk rotation unit and muscle responses for sudden upper limb loading by surface EMG. RESULTS: Lumbar perception threshold improved after surgery during 3-month follow-up (from 4.6° to 3.1°, P = 0.015) but tend to deteriorate again during 24 months (4.0°, P = 0.227). Preparatory paraspinal and BB muscle responses prior to sudden load as well as paraspinal muscle activation latencies after the load remained unchanged. CONCLUSION: Impaired lumbar proprioception seems to improve shortly after decompressive surgery but tends to deteriorate again with longer follow-up despite the sustaining favorable clinical outcome. The surgery did not affect either the feed-forward or the feed-back muscle function, which indicates that the abnormal muscle activity in LSS is at least partly irreversible.

MMI resonators based on metal mirrors and MMI mirrors: an experimental comparison.

We report, to the best of our knowledge, the first experimental proof of MMI-based resonators. The resonators have been designed and fabricated on a micron-scale silicon photonics platform and are based on different reflectors suitably placed on two of the four ports of 2x2 MMIs with uneven splitting ratios, namely 85:15 and 72:28. The reflectors are either based on aluminum mirrors or on all-dielectric MMI mirrors. Performances of the different designs are compared with each other and with numerical simulations. Finesse values as high as 13.1 (9.9) have been measured in best aluminum (all-dielectric) resonators, corresponding to a quality factor of 5.8·10(3) (12.5·10(3)) and mirror reflectivity exceeding 92% (88%).

Visually assessed severity of lumbar spinal canal stenosis is paradoxically associated with leg pain and objective walking ability.

BACKGROUND: Lumbar spinal stenosis (LSS) is the common term used to describe patients with symptoms related to the anatomical reduction of the lumbar spinal canal size. However, some subjects may have a markedly narrowed canal without any symptoms. This raises the question of what is the actual role of central canal stenosis in symptomatic patients. The purpose of this study was to compare radiological evaluations of LSS, both visually and quantitatively, with the clinical findings of patients with LSS. METHODS: Eighty patients [mean age 63 (11) years, 44% male], with symptoms severe enough to indicate LSS surgery, were included in this prospective single-center study. Lumbar magnetic resonance imaging was performed and one experienced neuroradiologist classified patients into three groups: 0 = normal or mild stenosis, 1 = moderate stenosis, and 2 = severe stenosis. In addition, the same observer measured the minimal dural sac area level by level from the inferior aspect of L1 to the inferior aspect of S1. The association between radiological and clinical findings were tested with Oswestry Disability Index, overall visual analog pain scale, specific low back pain, specific leg pain, Beck Depression Inventory, and walking distance on treadmill exercise test. RESULTS: In the visual classification of the central spinal canal, leg pain was significantly higher and walking distance achieved was shorter among patients with moderate central stenosis than in patients with severe central stenosis (7.33 (2.29) vs 5.80 (2.72); P = 0.008 and 421 (431) m vs 646 (436) m; P = 0.021, respectively). Patients with severe stenosis at only one level also achieved shorter walking distance than patients with severe stenosis of at least two levels. No correlation between visually or quantitatively assessed stenosis and other clinical findings was found. CONCLUSIONS: There is no straightforward association between the stenosis of dural sac and patient symptoms or functional capacity. These findings indicated that dural sac stenosis is not the single key element in the pathophysiology of LSS.

Preoperative MRI findings predict two-year postoperative clinical outcome in lumbar spinal stenosis.

PURPOSE: To study the predictive value of preoperative magnetic resonance imaging (MRI) findings for the two-year postoperative clinical outcome in lumbar spinal stenosis (LSS). METHODS: 84 patients (mean age 63±11 years, male 43%) with symptoms severe enough to indicate LSS surgery were included in this prospective observational single-center study. Preoperative MRI of the lumbar spine was performed with a 1.5-T unit. The imaging protocol conformed to the requirements of the American College of Radiology for the performance of MRI of the adult spine. Visual and quantitative assessment of MRI was performed by one experienced neuroradiologist. At the two-year postoperative follow-up, functional ability was assessed with the Oswestry Disability Index (ODI 0-100%) and treadmill test (0-1000 m), pain symptoms with the overall Visual Analogue Scale (VAS 0-100 mm), and specific low back pain (LBP) and specific leg pain (LP) separately with a numeric rating scale from 0-10 (NRS-11). Satisfaction with the surgical outcome was also assessed. RESULTS: Preoperative severe central stenosis predicted postoperatively lower LP, LBP, and VAS when compared in patients with moderate central stenosis (p<0.05). Moreover, severe stenosis predicted higher postoperative satisfaction (p = 0.029). Preoperative scoliosis predicted an impaired outcome in the ODI (p = 0.031) and lowered the walking distance in the treadmill test (p = 0.001). The preoperative finding of only one stenotic level in visual assessment predicted less postoperative LBP when compared with patients having 2 or more stenotic levels (p = 0.026). No significant differences were detected between quantitative measurements and the patient outcome. CONCLUSIONS: Routine preoperative lumbar spine MRI can predict the patient outcome in a two-year follow up in patients with LSS surgery. Severe central stenosis and one-level central stenosis are predictors of good outcome. Preoperative finding of scoliosis may indicate worse functional ability.

Correlation of lateral stenosis in MRI with symptoms, walking capacity and EMG findings in patients with surgically confirmed lateral lumbar spinal canal stenosis.

BACKGROUND: To evaluate the clinical significance of lateral lumbar spinal canal stenosis (LLSCS), found by magnetic resonance imaging (MRI), through correlating the imaging findings with patient symptoms, walking capacity and electromyography (EMG) measurements. METHOD: 102 patients with symptoms of LSS referred for operative treatment were studied in this uncontrolled study. Of these patients, subjects with distinct only lateral LSS were included. Accordingly, 140 roots in 14 patients (mean age 58, range 48-76 years, male 43%) were evaluated. In MR images the entrance and mid zones of the lateral lumbar nerve root canal were graded as normal, narrowed but not compressed, or compressed. In quantitative analysis, the minimal widths of the lateral recess and mid zone area were measured. Clinical symptoms were recorded with the Oswestry Disability Index (ODI), overall Visual Analogue Scale (VAS), specific low back pain (LBP; NRS-11), specific leg pain (LP NRS-11), Beck Depression Inventory (BDI) and walking distance in the treadmill test. Lumbar paraspinal (L2- L5) and lower limb (L3 - S1) needle EMG studies were performed. The findings were classified root by root as 1 = normal, 2 = abnormal. The associations between radiological, EMG and clinical findings were tested with each other. RESULTS: EMG findings were normal in 92 roots and abnormal in 48 roots. All of the patients had at least one abnormal nerve root finding. Severity of the mid zone stenosis in MRI correlated with abnormal EMG findings (p = 0.015). Patients with abnormal EMG had also higher scores in the VAS (41.9 ± 25.7 vs 31.5 ± 18.1; p = 0.018), NRS leg pain (7.5 ± 1.5 vs 6.3 ± 2.1; p = 0.000) and BDI (9.8 ± 3.8 vs 8.0 ± 3.9; p = 0.014). However, no statistically significant correlations between MRI findings and clinical symptoms or walking capacity were found. CONCLUSIONS: Among persons previously selected for surgery, lateral stenosis seen on MRI correlates with EMG, and thus may be a clinically significant finding. Our EMG findings were also associated with patient symptoms. However, no relationships between the MRI findings and symptoms or walking capacity were found, suggesting their multifactorial etiology.

Unconstrained splitting ratios in compact double-MMI couplers.

A novel guided-wave optical power coupler is presented, based on two 2x2 50/50 multimode interference splitters connected with tapered waveguides that play the role of a phase shifter. By simply changing the length of this phase shifter, these double-MMI couplers can be easily designed to get any desired splitting ratio. Results of simulations are discussed and compared with the characterizations of devices fabricated on micron-scale SOI wafers, to highlight pros and cons of the proposed solution. The fabricated splitters have been found to have average losses about 0.4 ± 0.5 dB and splitting ratios ranging from 56/44 to 96/4.

Depressive burden is associated with a poorer surgical outcome among lumbar spinal stenosis patients: a 5-year follow-up study.

BACKGROUND CONTEXT: In lumbar spinal stenosis (LSS), conservative treatment is usually the first choice of treatment. If conservative treatment fails, surgery is indicated. Psychological factors such as depression and anxiety are known to affect the outcome of surgery. Previous studies on depression and surgery outcome using long follow-up times are scarce. PURPOSE: The purpose of this study was to investigate the effect of depressive symptoms on the surgical outcome during a 5-year follow-up among patients with LSS. STUDY DESIGN: A prospective observational study. PATIENT SAMPLE: Patient sample included 102 LSS patients who needed surgical treatment. OUTCOME MEASURES: The outcome of surgery was evaluated with the Oswestry Disability Index (ODI), visual analog scale pain assessment, and self-reported walking capacity. METHODS: The patients completed a set of questionnaires preoperatively and 3 and 6 months, as well as 1, 2, and 5 years after the surgery. Depressive symptoms were assessed with the Beck Depression Inventory. The depressive burden was estimated by summing all individual Beck Depression Inventory scores. Statistical analyses included cross-sectional group comparisons and linear regression analyses. No conflicts of interest. RESULTS: On 5-year follow-up, a high depressive burden associated with a poorer outcome of surgery when assessed with the ODI. In linear regression analysis, a high depressive burden associated with higher ODI score. CONCLUSIONS: Even slightly elevated long-term depressive symptoms in LSS patients are associated with an increased risk of a poorer functional ability after decompressive surgery.

Life dissatisfaction burden is associated with a poor surgical outcome among lumbar spinal stenosis patients: a 5-year follow-up study.

Dissatisfaction with life has been found to be associated with somatic health and the short-term surgery outcome in lumbar spinal stenosis (LSS) patients. This study investigated the effects of the long-term life dissatisfaction burden on the surgery outcome in LSS patients with a 5-year follow-up. This was a prospective clinical study. Altogether, 102 patients who underwent decompressive surgery completed a set of questionnaires preoperatively, 3 and 6 months, and 1, 2 and 5 years after the surgery. The final study population at the 5-year follow-up included 67 patients. The mean age of the patients was 67 years and 35% of the patients were men. Life satisfaction was evaluated using a four-item Life Satisfaction Scale. The life dissatisfaction burden was the sum of all six life satisfaction scores recorded during the follow-up. The outcome of surgery was evaluated using the Oswestry Disability Index (ODI), pain evaluation (Visual Analogue Scale; VAS), overall satisfaction with the surgery and self-reported walking capacity. In linear regression, the long-term life dissatisfaction burden was associated with the 5-year ODI, even after adjusting for age, sex, marital status, preoperative ODI and the 5-year VAS. It was not associated with the 5-year VAS score. Monitoring the life satisfaction of surgically treated LSS patients may enable detection of those at risk of a poorer surgery outcome.

Dramatic size reduction of waveguide bends on a micron-scale silicon photonic platform.

We demonstrate theoretically and experimentally how highly multimodal high index contrast waveguides with micron-scale cores can be bent, on an ultra-broad band of operation, with bending radii below 10 µm and losses for the fundamental mode below 0.02 dB/90°. The bends have been designed based on the Euler spiral and fabricated on 4 µm thick SOI. The proposed approach enabled also the realization of 180° bends with 1.27 µm effective radii and 0.09 dB loss, which are the smallest low-loss bends ever reported for an optical waveguide. These results pave the way for unprecedented integration density in most semiconductor platforms.

Lumbar paraspinal and biceps brachii muscle function and movement perception in lumbar spinal stenosis.

INTRODUCTION: Impaired muscle function and lumbar proprioception have been observed in lumbar spinal stenosis (LSS) but those have not been studied in LSS patients with age-matched controls. We assessed lumbar movement perception and paraspinal and biceps brachii (BB) muscle responses during sudden upper limb loading in age-matched healthy subjects and patients with LSS. METHODS: The study included 30 patients selected for an operation due to LSS and 30 age-matched controls without chronic back pain. The paraspinal and BB muscle responses for upper limb loading during unexpected and expected conditions were measured by surface EMG. The ability to sense lumbar rotation was assessed in a previously validated motorized trunk rotation unit in a seated position. Pain, disability and depression scores were recorded. RESULTS: Patients had poorer lumbar perception (mean difference 2.3 ± 0.6°, P < 0.001) and longer paraspinal muscle response latencies [mean difference 4.6 ± 0.6 ms (P = 0.033)] than age-matched healthy controls. Anticipation increased paraspinal and BB muscle activation prior to the load perturbation (P < 0.001) but less in LSS patients than in controls [9 vs. 30 %, P = 0.016 (paraspinals); 68 vs. 118 %, P = 0.047 (BB)]. CONCLUSIONS: The observed impairments in lumbar proprioception and activation of paraspinal and upper limb muscles indicate an extensive loss of both sensory and motor functions in LSS. The main new finding was decreased anticipatory muscle activation during expected upper limb loading reflecting involvement of central movement control mechanisms.

Accuracy and reproducibility of a retrospective outcome assessment for lumbar spinal stenosis surgery.

BACKGROUND: Retrospective assessment of surgery outcome is considered problematic. The aims of this study were to evaluate the reproducibility and accuracy of a retrospective outcome assessment of lumbar spinal stenosis surgery with reference to prospective outcome scale measurements. METHOD: Outcome of surgery from 100 lumbar spinal stenosis (LSS) patients was evaluated retrospectively from patient files of a 3-month outpatient visit performed according to a standard clinical protocol by two independent researchers. In the retrospective analysis, outcome was graded as 2 = good if the clinical condition had clearly improved, 1 = moderate if it had just slightly improved, 0 = poor if it had not improved or was even worse than before the surgical treatment (Retrospective 3- point scale). A prospectively assessed Oswestry Disability Index questionnaire (ODI), Visual analogue pain scale (VAS) and a patient satisfaction questionnaire were used as references of standards. Reproducibility of the measurements was evaluated. RESULTS: The retrospective 3-point scale correlated with ODI (r = 0.528; P < 0.001) and VAS (r = 0.368; P < 0.001). The agreement was better in the good and poor outcome than in the moderate outcome. Retrospective 3-point scale demonstrated substantial intra-rater and inter-rater repeatability (κ = 0.682, P < 0.001 and κ = 0.630, P < 0.001, respectively). CONCLUSIONS: Retrospective assessment of spinal surgery outcome is highly reproducible. Accuracy is highest in the patients with poor and good surgical result.

Lumbar instrumented posterolateral fusion in spondylolisthetic and failed back patients: a long-term follow-up study spanning 11-13 years.

UNLABELLED: INTRODUCTION AND MATERIALS: We examined lumbar transpedicular instrumented posterolateral fusion patients operated on between 1992 and 1997 presenting: degenerative spondylolisthesis with spinal stenosis; adult isthmic spondylolisthesis; failed back syndrome after one to five discectomies; and failed back syndrome after one to three laminectomy operations (groups 1-4, respectively). METHODS: They were examined by an independent orthopedic surgeon, completed the Oswestry Disability Index (ODI) and visual analog scale (VAS) questionnaires and their outcome was evaluated. RESULTS: The overall patient satisfaction at follow-up (mean 11.7 years) was 82.1%. The reoperation rate was 15.1% (7.5% due to adjacent segment disease). CONCLUSION: Group 1 showed the greatest improvements in ODI and VAS values, Group 2 the lowest and Group 3 the highest preoperative values, and Group 4 the second highest improvements. Patient satisfaction scores were 90.3, 69.7, 63.6 and 80.0%, respectively, and unplanned reoperation rates were 6.5, 9.1, 31.8 and 20.0%. Thus, long-term outcomes of lumbar instrumented posterolateral fusion (rarely previously studied) were satisfactory for >80% of patients, but varied among groups.

Visual and quantitative assessment of lateral lumbar spinal canal stenosis with magnetic resonance imaging.

BACKGROUND: Lateral lumbar spinal canal stenosis is a common etiology of lumbar radicular symptoms. Quantitative measurements have commonly demonstrated better repeatability than visual assessments. We are not aware of any studies examining the repeatability of quantitative assessment of the lateral canal. PURPOSE: To evaluate the repeatability of visual assessments and newly developed quantitative measurements of lateral lumbar spinal canal stenosis using magnetic resonance imaging (MRI). MATERIAL AND METHODS: Twenty-eight patients with lateral lumbar spinal canal stenosis or prior spinal surgery with recurrent symptoms were imaged with MRI. A radiologist, a neurosurgeon and a spine research trainee graded visually and quantitatively subarticular (n = 188) and foraminal zones (n = 260) of the lateral spinal canal. Quantitative measurements included the minimal subarticular width and the cross-sectional area of the foramen. RESULTS: The repeatability of visual assessment at the subarticular zone and foraminal zones between raters varied from 0.45-0.59 and 0.42-0.53, respectively. Similarly, the intraclass correlation coefficients for the quantitative measurements varied from 0.67-0.71 and 0.66-0.76, respectively. The intra-rater repeatability for the visual assessments of the subarticular and foraminal zones was 0.70 and 0.62, respectively, while the corresponding intraclass correlation coefficients for quantitative measurements were 0.83 and 0.81, respectively. CONCLUSION: Inter-rater repeatability of visual assessments of lateral stenosis is moderate, whereas quantitative measurements of both subarticular width and the cross-sectional area of the foramen have substantial reproducibility and may be particularly useful for longitudinal studies and research purposes. The clinical value of these parameters requires further study.