The gaps in health-adjusted life Expectancy (HALE) by income and region in Korea

 

This study aims to calculate the health-adjusted life expectancy (HALE) by using years lived with disability (YLD) from the national claims data, as well as to identify the differences and inequalities in sex, income level and region. The study was carried out on total population receiving national health insurance and medical benefits. We calculated incidence-based YLD for 260 disease groups, and used it as the number of healthy years lost to calculate HALE. We adopted the insurance premium to calculate the income as a proxy indicator. For the region classification, we chose 250 Korean municipal-level administrative districts. The primary outcome was HALE in the Korean population. The second outcome was the HALE’s gap in terms of sex, income, and region. Our results revealed that HALE increased from 2008 (68.89 years) to 2019 (70.58 years). HALE in males increased faster than that in females. HALE was higher in higher income levels. In 2019, the gap in HALE between Q1 and Q2, the lower income group, was about 5.70 years. The gap in females by income level was smaller than that in males. Moreover, the gap in HALE by region was found to increase. Results suggest that there is an inequality in YLD in terms of income level in Korea. Therefore, we need intensive management for the low-income group to increase HALE at the national level.

Key messages

• Males’ health level may be more sensitive to the socioeconomic level than females’ health level.

• In the 5th National Health Plan (HP2030), it was decided to set a target value for the overall goals based on this result.

Association of COVID-19 with skin diseases and relevant biologics: a cross-sectional study using nationwide claim data in South Korea

Background

As the coronavirus disease 2019 (COVID‐19) pandemic has spread, information about COVID‐19 and skin disease or related biologics is still lacking.

Objectives

To identify the association between COVID‐19 and skin diseases or biologics.

Methods

A nationwide claim dataset relevant to COVID‐19 in South Korea was analysed. This dataset included insurance claim data before and during COVID‐19 treatment and clinical outcomes. Claim data related to skin diseases and relevant biologics were analysed to determine the association of COVID‐19 with skin diseases and relevant biologics.

Results

The dataset contained a total of 234 427 individuals (111 947 male and 122 480 female) who underwent COVID‐19 testing. Of them, 7590 (3·2%) were confirmed as having COVID‐19, and 227 (3·0%) confirmed patients died. Among various skin diseases and biologics, no significant increase in the presence of specific skin diseases or exposure to biologics was observed in the COVID‐19‐positive group, even after adjusting for or matching covariates. The presence of skin diseases and exposure to biologics also did not seem to affect clinical outcomes including mortality.

Conclusions

Underlying skin diseases did not appear to increase susceptibility to COVID‐19 or mortality from COVID‐19. Considering the risks and benefits, biologics for dermatological conditions might be continuously used during the COVID‐19 pandemic.

Conducting a national burden of disease study in South Korea: from past to present

South Korea has been measuring its own burden of disease since the early 2000s and has developed a methodology for its calculation. Since 2012, South Korea has been carrying out disease burden research through the Research and Development Project, supported by the Ministry of Health and Welfare. Because the Korean health insurance system covers the entire population of the country, the Korean National Burden of Disease (KNBD) study is based on individual claims data. Disease prevalence, incidence, and mortality rates, which are the epidemiologic indicators used to calculate burden of disease, are based on actual data, and the incidence-based approach is used for Years Lived with disability (YLD), Years of Life Lost (YLL), and Disability Adjusted Life Year (DALY). The KNBD study is conducted for 260 diseases and injuries and subdivided into sub-national levels. Disability weights (DW) are calculated to reflect the sociocultural characteristics of a disease. For cause-specific DWs, we conducted a self-administered web-based survey for medical doctors and students. Using a ranking method, we calculated cause-specific DWs. For this reason, KNBD study results cannot be directly compared with GBD results.

The major findings of the KNBD study are as follows. In Korea, the DALY rate (per 100,000 people) steadily increased for all income levels. The higher the income, the lower the burden of disease; low-income people had a higher burden of disease than high-income people. However, thyroid cancer, refraction and accommodation disorders had a high burden of disease in the high-income group. Growth in the YLD rate was faster than in the YLL rate. In 2016 the leading causes of disease burden were diabetes mellitus, low back pain, and chronic obstructive pulmonary disease.

We will present South Korea's disease burden calculation methodology and its results and share the efforts to calculate disease burden in other countries.

Arctium lappa root extract containing L-arginine prevents TNF-α-induced early atherosclerosis in vitro and in vivo

Atherosclerosis is a chronic inflammatory disease affecting the aorta and is a major cause of cardiovascular disease. Arctium lappa root is a plant widely used in traditional Chinese medicine (TCM), and Arctium lappa root extract (ALE) has been reported to exhibit anti-inflammatory capacity and to ameliorate endothelial dysfunction. Thus, we hypothesized that ALE would inhibit the early atherosclerotic stage. In this study, we evaluated the inhibitory effect of ALE on early arteriosclerosis and its mechanisms of action. ALE suppressed TNF-α-induced monocyte adhesion to the vascular endothelium by suppressing NF-κB signaling in HUVECs. In an acute mouse model of atherosclerosis, ALE suppressed TNF-α-induced monocyte infiltration of the vascular endothelium and the expression of genes encoding inflammatory cytokines including IL-1β, IL-6, TNF-α, and MCP-1 in the mouse aorta. Moreover, inulin-type fructan and amino acids, especially L-aspartate and L-arginine (60.27 and 42.17 mg/g, respectively) were detected by NMR, MALDI-TOF MS, and HPLC analysis as the main components of ALE. Notably, L-arginine suppressed TNF-α-induced monocyte adhesion to HUVECs. Therefore, these results suggest that ALE may be a functional food for the suppression or prevention of early stages of atherosclerosis.

Enhancement of the apoptotic effects of Arctii Fructus extracts on cancer cells by the enzymatic bioconversion of lignans

The fruit of Arctium lappa L. (Arctii Fructus) is one of the most popularly used medicinal plant components in Asia. To enhance the functionality of Arctii Fructus extract, a bioconversion method was developed to produce arctigenin from arctiin. Treatment with β-glucosidase increased the arctigenin content by >5 fold in Arctii Fructus extracts. The bioconversion products enhanced the apoptosis of cancer cells. The cell viabilities of gefitinib-resistant lung cancer HCC827 (HCC827GR) cells and colon cancer cells (DLD1) were decreased by 40% and 35%, respectively. The bioconversion products also decreased anchorage-independent growth of cancer cells. In addition, the increase of apoptosis in cancer cells by bioconversion was confirmed by the flow cytometry analysis. These results indicated that arctigenin exerts anticancer effects on lung and colon cancer cells and that Arctii Fructus can potentially function as a chemopreventive agent. In addition, bioconverted Arctii Fructus extract displayed higher anticancer activity than the same levels of purified arctigenin, indicating the advantage of consuming Arctii Fructus itself as a food or medicinal material.

Lymph node size is not a reliable criterion for predicting nodal metastasis in rectal neuroendocrine tumours

AIM

The study was designed to assess the correlation between lymph node (LN) size and LN metastasis in patients with rectal neuroendocrine tumours (NETs).

METHOD

Forty patients who underwent curative resection with lymphadenectomy for a rectal NET between January 2007 and December 2012 were included. The short and long diameters of entire nodes were microscopically measured using a slide gauge.

RESULTS

In all, 1052 LNs were collected from the 40 patients, with 49 (4.7%) showing evidence of metastasis. Metastasis-positive LNs had significantly greater long and short diameters (P < 0.001) than metastasis-negative LNs. Of the 49 metastatic LNs, 29 (59.2%) were ≤ 5 mm in largest diameter. In five patients, the largest metastatic LN was only 2-3 mm in diameter. In clinically node-negative (cN0) patients, 18 (51.4%) patients had metastatic LNs (pN1).

CONCLUSION

The size of LNs containing metastasis varied widely, with some being very small. LN size alone is therefore not a sufficient predictor of tumour metastasis in rectal NETs. Radical surgery with lymphadenectomy should be considered for patients with rectal NETs with high risk factors for LN metastasis, even those without LN enlargement.

Cyanidin-3-glucoside isolated from mulberry fruits protects pancreatic β-cells against glucotoxicity-induced apoptosis

The present study investigated the cytoprotective effects of cyanidin‑3‑glucoside (C3G), isolated from mulberry fruits, on the glucotoxicity‑induced apoptosis of pancreatic β‑cells to evaluate the antidiabetic effects of this compound. MIN6N pancreatic β‑cells were used to investigate the cytoprotective effects of C3G. In addition, the effects of C3G on the glucotoxicity‑induced apoptosis of pancreatic β‑cells was evaluated using MTT assay, immunofluorescent staining, flow cytometric and western blot analyses. The pancreatic β‑cells cultured under high glucose conditions exhibited distinct apoptotic features. C3G decreased the generation of intracellular reactive oxygen species, DNA fragmentation and the rate of apoptosis. C3G also prevented pancreatic β‑cell apoptosis induced by high glucose conditions by interfering with the intrinsic apoptotic pathways. In addition, C3G treatment resulted in increased insulin secretion compared with treatment with high glucose only. In conclusion, the results of the present study suggested that C3G obtained from mulberry fruits may be a potential phytotherapeutic agent for the prevention of diabetes.

Cyanidin-3-glucoside isolated from mulberry fruit protects pancreatic β-cells against oxidative stress-induced apoptosis

The extract obtained from berries contains high amounts of anthocyanins, and this extract is used as a phytotherapeutic agent for different types of diseases. In this study, we examined the cytoprotective effects of cyanidin-3-glucoside (C3G) isolated from mulberry fruit against pancreatic β-cell apoptosis caused by hydrogen peroxide (H2O2)-induced oxidative stress. The MIN6 pancreatic β-cells were used to investigate the cytoprotective effects of C3G on the oxidative stress-induced apoptosis of cells. Cell viability was examined by MTT assay and lipid peroxidation was assayed by thiobarbituric acid (TBA) reaction. Immunofluorescence staining, flow cytometry and western blot analysis were also used to determine apoptosis and the expression of proteins associated with apoptosis. Our results revealed that H2O2 increased the rate of apoptosis by stimulating various pro-apoptotic processes, such as the generation of intracellular reactive oxygen species (ROS), lipid peroxidation, DNA fragmentation and caspase-3 activation. However, C3G reduced the H2O2-induced cell death in the MIN6N pancreatic β-cells. In addition, we confirmed that H2O2 activated mitogen-activated protein kinases (MAPKs), such as extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK) and p38 MAPK. C3G inhibited the phosphorylation of ERK and p38 without inducing the phosphorylation of JNK. Furthermore, C3G regulated the intrinsic apoptotic pathway-associated proteins, such as proteins belonging to the Bcl-2 family, cytochrome c and caspase-3. Taken together, our results suggest that C3G isolated from mulberry fruit has potential for use as a phytotherapeutic agent for the prevention of diabetes by preventing oxidative stress-induced β-cell apoptosis.

Mulberry fruit extract protects pancreatic β-cells against hydrogen peroxide-induced apoptosis via antioxidative activity

Among the many environmental stresses, excessive production of reactive oxygen species (ROS) and the ensuring oxidative stress are known to cause significant cellular damage. This has clinical implications in the onset of type 1 diabetes, which is triggered by the destruction of pancreatic β-cells and is associated with oxidative stress. In this study, we investigated the protective and antioxidative effects of mulberry extract (ME) in insulin-producing pancreatic β-cells. We found that ME protects pancreatic β-cells against hydrogen peroxide (H₂O₂)-induced oxidative stress and the associated apoptotic cell death. ME treatment significantly reduced the levels of H₂O₂-induced 2-diphenyl-1-picrylhydrazyl (DPPH) radicals, and lipid peroxidation and intracellular ROS accumulation. In addition, ME inhibited DNA condensation and/or fragmentation induced by H₂O₂. These results suggest that ME protects pancreatic β-cells against hydrogen peroxide-induced oxidative stress.

Pantothenate kinase-associated neurodegeneration in Korea: recurrent R440P mutation in PANK2 and outcome of deep brain stimulation

BACKGROUND AND PURPOSE

The purpose of this study was to evaluate the mutation status of PANK2 among Korean patients with pantothenate kinase-associated neurodegeneration (PKAN) and to document the outcome of pallidal deep brain stimulation (DBS).

METHODS

Direct sequencing and deletion/duplication analysis of PANK2 were conducted in 12 patients (11 unrelated) with PKAN, diagnosed on the basis of extrapyramidal dysfunction and the 'eye-of-the-tiger sign' on brain magnetic resonance imaging (MRI). Pallidal DBS was conducted in four patients, and the outcomes were measured using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS).

RESULTS

A PANK2 mutation was identified in both alleles in all patients. The most prevalent mutation was c.1319G>C (p.R440P) in 8/22 mutated alleles (36%). An intragenic deletion ranging from exons 2 to 4 was found in one allele (1/22, 4.5%) using deletion/duplication analysis. The outcome of pallidal DBS was favorable in two patients with atypical PKAN and moderate severity of dystonia. However, two patients with typical PKAN and relatively severe symptoms showed variable responses.

CONCLUSIONS

The c.1319G>C (p.R440P) mutation appears to be a founder genotype among Korean patients with PKAN. Furthermore, this study provides additional data for the recent international effort to evaluate the efficacy of pallidal DBS in the treatment of patients with PKAN.

Structural characteristics of immunostimulating polysaccharides from lentinus edodes

There is a significant amount of experimental evidence suggesting that polysaccharides from mushrooms enhance the host immune system by activating various mechanisms in immune cells, including macrophages. In this study, polysaccharides from Lentinus edodes were found to stimulate the functional activation of macrophages to secrete inflammatory mediators and cytokines and increase the phagocytotic uptake. The chemical properties of the stimulatory polysaccharides, CPFN-G-I, CPBN-G, and CPBA-G, were determined based on their monosaccharide composition, which mainly consisted of glucose and mannose. According to FT-IR and GC/MS, the structure of CPFN-G-I, purified from the fruiting body of L. edodes, was found to consist of a beta-1,6-branched-beta-1,4-glucan, whereas CPBN-G and CPBA-G, purified from the liquid.

Study on immunostimulating activity of macrophage treated with purified polysaccharides from liquid culture and fruiting body of Lentinus edodes

Lentinus edodes is a well-known edible and medicinal mushroom used in Oriental cultures. Recently, L. edodes has attracted a lot of attention owing to its antifungal activity, antibacterial activity, antiviral activity, hepatoprotective effect, antitumor activities, and immunomodulatory and cytotoxic effects. In this study, the water-soluble crude polysaccharides, CPF and CPB, which were obtained from the fruiting body and culture cell-free broth of L. edodes by hot-water extraction and ethanol precipitation, were fractionated by DEAE cellulose and Sepharose CL-6B column chromatography, resulting in six polysaccharide fractions, CPFN-G-I, CPFN-G-II, CPFN-G-III, CPFA-G, CPBN-G, and CPBA-G. Among these fractions, CPFN-GI, CPBN-G, and CPBA-G were shown to stimulate the functional activation of macrophages including NO production cytokine expression and phagocytosis.

Association of serum lipids and glucose with the risk of colorectal adenomatous polyp in men: a case-control study in Korea

Previous studies on life style for colorectal cancer risk suggest that serum lipids and glucose might be related to adenomatous polyps as well as to colorectal carcinogenesis. This case-control study was conducted to investigate the associations between serum lipids, blood glucose, and other factors and the risk of colorectal adenomatous polyp. Male cases with colorectal adenomatous polyp, histologically confirmed by colonoscopy (n=134), and the same number of male controls matched by age for men were selected in hospitals in Seoul, Korea between January 1997 and October 1998. Serum lipids and glucose levels were tested after the subjects had fasted for at least 12 hr. Conditional logistic regression showed that there was a significant trend of increasing adenomatous polyp risk with the rise in serum cholesterol level (Ptrend=0.07). Increasing trend for the risk with triglyceride was also seen (Ptrend=0.01). HDL-cholesterol and LDL-cholesterol had increasing trends for the risk, which were not significant. In particular, it was noted that higher fasting blood glucose level reduced the adenomatous polyp risk for men (Ptrend=0.001). This study concluded that both serum cholesterol and triglyceride were positively related to the increased risk for colorectal adenomatous polyp in Korea. Findings on an inverse relationship between serum glucose and the risk should be pursued in further studies.

Impact response of the intervertebral disc in a finite-element model

STUDY DESIGN

A three-dimensional nonlinear poroelastic finite-element model of a vertebra disc was used to analyze the biomechanical effects of impact loading on the spinal segment.

OBJECTIVES

To predict changes in biomechanical parameters such as intradiscal pressure, dynamic stiffness, stresses in the endplate region, and the shock-absorbing mechanism of the spine under different impact duration/loading rates, and to investigate the relation between the rate of loading and the fracture potential of the vertebral body.

SUMMARY OF BACKGROUND DATA

It is not practical to discern the role of impact duration using experimental protocols. Analytical studies are better suited to this purpose. However, previous poroelastic finite-element models of the motion segments have dealt mostly with creep phenomena.

METHODS

A three-dimensional, L3-L4 motion-segment, finite-element model was modified to incorporate the poroelastic properties of the disc, endplate, and cancellous core, and thus simulate the shock-absorbing phenomena. The results were analyzed under variable impact durations for a constant maximum compressive impact load of 3 kN.

RESULTS

For a shorter impact duration and a given F(max), relatively high cancellous core pressure was generated as compared with a case of long impact duration, although the amount of impulse was increased. In contrast, relatively constant pore pressures were generated in the nucleus regardless of the impact duration. The changes in spinal segment stiffness as a function of impact duration indicated that for a shorter duration of impact, high dynamic stiffness increases the stability of the spinal segment against the impact load. However, the corresponding increase in stresses within the vertebral body and endplate may produce fractures.

CONCLUSIONS

The finite-element technique was used to address the role of impact duration in producing trauma to the spinal motion segment. Within the limitations of the model, the results suggest that fractures are likely to occur under shorter impact duration conditions. Depending on the strength of the region, a fracture may be initiated in the endplate region or the posterior wall of the cortical shell. The nucleus pressure is independent of the impact duration and depends only on the magnitude of the impact force.

The geography of survival after surgery for colo-rectal cancer in southern England

This study investigates variations in survival following surgery for colo-rectal cancer in the Wessex region (part of southern England), using 5147 cases diagnosed between 1 September 1991 and 31 August 1995. Survival curve estimation by life tables and Cox's proportional hazards model were used to examine geographical variation in cancer survival, with a specific focus on distance between place of residence and treatment centre, and district of treatment. We also consider whether area deprivation has an impact on survival. In seeking to answer these questions we control for possible confounders, including: age, gender, site of tumour, stage of disease at operation, hospital size and surgery type (whether elective or non-elective). District of treatment, distance and deprivation all show a relationship to outcome using survival curves, but when adjusting for other covariates using the Cox model, and considering deaths from all causes, only district of treatment was a very significant covariate (p < 0.0001). Distance, deprivation, and gender were only weakly significant (p < 0.10). Considering only deaths related to operation (within 30 days) district of treatment remained significant, but while distance had some effect on outcome, deprivation and gender ceased to be significant covariates. There is some evidence that those who live furthest from centres of treatment have the worst outcomes but the 'geography of survival' manifests itself more through where patients are treated than through area (deprivation) effects or relative location. The results have important policy implications, as they show variations among treatment centres having controlled for potentially confounding factors.

Comparison of transplacental and neonatal initiation of mouse lung and liver tumors by N-nitrosodimethylamine (NDMA) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and promotability by a polychlorinated biphenyls mixture (Aroclor 1254)

We have previously shown a positive tumor-promoting effect of a single dose of Aroclor 1254 on lung and liver tumors initiated neonatally in the mouse by N-nitrosodimethylamine (NDMA). In this study, we have confirmed and extended this observation with NDMA and the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) given either transplacentally or postnatally, followed by a single dose of Aroclor 1254 on day 56. This polychlorinated biphenyl (PCB) mixture was an effective promoter of both lung and liver tumors; however, there were specific initiator and sex-related differences in this response. Aroclor administration significantly increased the incidence of lung tumors initiated transplacentally by NDMA or NNK in male mice. Neither nitrosamine initiated tumors transplacentally in females, but lung tumors initiated with NNK and liver tumors caused by NDMA in neonatal females were promoted by PCBs. Both liver and lung tumors initiated neonatally by NDMA in male animals, but not NNK-initiated tumors, were promoted by PCBs. These data confirm that PCBs are able to promote both NDMA- and NNK-initiated tumors, but with chemical-, sex- and age-dependent difference; this suggests influences of both quantitative and qualitative factors in susceptibility to tumor promotion.

Effect of disc degeneration at one level on the adjacent level in axial mode

Nonlinear three-dimensional finite element models of a ligamentous two motion segments spine specimen (L3-L4-L5) were developed to investigate the effects of disc degeneration, simulated at the L4-L5 level, on the biomechanical behavior of the adjacent intact L3-L4 motion segment. The disc degeneration was simulated by removing the hydrostatic capabilities of the nucleus and making the L4-L5 disc stiffer than a normal disc. The results of the degenerated model were compared with the predictions for a model in which the L4-L5 disc was left intact. The loads on the facets decreased, and intradiscal pressure in the intact L3-L4 disc increased as a result of disc degeneration compared with the intact model. The predicted increase in the intradiscal pressure and the associated increase in the disc bulge in the posterior region over time may trigger the degenerative process at the L3-L4 motion segment. This is in accordance with the Wolff's law; living tissue responds to chronic changes in stresses and strains. The limitations of the present two motion segments model and the potentials of multisegmental models are discussed.

Possible role of stresses in inducing spinal stenosis--a long term complication following disk excision

A three-dimensional finite element model of an intact ligamentous lumbar motion segment (L3-4) was used to predict stresses in the pars interarticularis regions of the modeled vertebral bodies. The changes in stresses following disk excision, as compared to the intact model, also were computed. The predicted results show an increase in stresses in the posterior bony elements following disk excision. In some patients over a long period of time this increase in stresses, in association with other clinical factors, may lead to bony hypertrophy of the structures that surround the nerve roots. Ultimately, over a long period of time the increase in pressure on the entrapped nerve root may induce recurrent pain and other complications reported in the literature.

Evaluation of effectiveness of a facet wiring technique: an in vitro biomechanical investigation

The effects of facet wiring procedure commonly used for stabilizing cervical spines after laminectomy or bilateral facet dislocation on the motion behavior of whole cervical spines are investigated using a Selspot II system. A fresh human ligamentous intact specimen was potted at T1/T2 vertebra and clinically relevant loads applied to the topmost vertebra (C2) of the specimen. The resulting three rotational components of each of the five vertebral bodies (C3-C7) were recorded. Specimen was injured to mimic total laminectomies at C5 and C6 vertebral levels and tested again. The injured specimen was stabilized, using a facet wiring construct, across C4-C7 segment before testing for the final time. The injured specimens, compared to the intact specimens, demonstrated an increase in flexion-extension of about 10%. Facet wiring imparted stability to the cervical spine by stiffening segments up to roughly four times intact values.

An analytical investigation of the mechanics of spinal instrumentation

Three-dimensional nonlinear finite element models of the intact L4-5 one motion segment/two-vertebrae and L3-5 two motion segments/three-vertebrae were developed using computed tomography (CT) films. The finite element mesh of the L4-5 motion segment model was modified to simulate bilateral decompression surgery. The mesh was further altered to achieve stabilization, using an interbody bone graft and a set of Steffee plates and screws. The model behavior of the intact specimen in all loading modes and of the stabilized model in compression, flexion, and extension modes were studied. The stresses in the cancellous bone region were found to decrease. The interbody bone graft, due to an overall decrease in stresses in the bone below the screw, transmits about 80% of the axial load as compared with 96% transmitted by an intact disc in an intact model. Thus, the use of a fixation device induces a stress shielding effect in the vertebral body. The results indicate that although the bone graft transmits lesser loads than the intact disc, it is active in transmitting loads. The presence of low stresses in the cancellous bone region and high localized stresses in the cortical pedicle region surrounding the screw, compared with the intact case, suggests that the screws are likely to become loose over time. The use of an interbody bone graft alone or in combination with any existing fixation device also induces higher stresses at the adjacent levels. This may be responsible for the adverse iatrogenic effects seen clinically.

Load sharing among spinal elements of a motion segment in extension and lateral bending

A linear optimization model was formulated using a semi-experimental protocol to estimate the forces in the spinal elements of a lumbar motion segment subjected to an extension or lateral bending moment with and without a 120 N compressive preload. A morphometer was used to acquire the three-dimensional locations of the disk center, facet centers and ligament origin and insertion sites with the specimen in a "neutral" position. The relative motion of the superior vertebra, under the loading conditions tested, was monitored using a Selspot II system. These data allowed the formulation of the static equilibrium equations for the superior vertebra at each of the loading conditions mentioned above. A linear optimization technique was used, along with a suitable cost function, to find an optimum solution for the set of equations and imposed constraints. Results showed that for 6.9 Nm of extension moment, each facet carried a load of 52 N, with the disk carrying an axial tensile load of 104 N. At the 6.9 Nm extension moment coupled with 120 N preload, each facet carried a load of 77.2 N and the disk an axial tensile load of 37 N. In right lateral bending, with and without preload, the load was distributed among the right facet, the disk, the left ligamentum flavum and the left capsular ligament. At the 6.9 Nm load step without preload the right facet carried an axial load of 127.01 N with the disk carrying an axial compressive load of 7.8 N. Ligament forces for this step for the left ligamentum flavum and capsular ligament, respectively, were 61.03 N and 65.14 N. The addition of 120 N of preload reduced the load on the right facet to 83.5 N. The compressive load in the disk increased to 107.5 N. The corresponding ligament forces were 43.2 N (left ligamentum flavum) and 50.7 N (left capsular ligament).