Evaluation of Anatomical and Functional Hip Joint Center Methods: The Effects of Activity Type, Gender, and Proximal Reference Segment.

Accurate hip joint center (HJC) location is critical when studying hip joint biomechanics. The HJC is often determined from anatomical methods, but functional methods are becoming increasingly popular. Several studies have examined these methods using simulations and in vivo gait data, but none has studied high-range of motion activities, such a chair rise, nor has HJC prediction been compared between males and females. Furthermore, anterior superior iliac spine (ASIS) marker visibility during chair rise can be problematic, requiring a sacral cluster as an alternative proximal segment; but functional HJC has not been explored using this approach. For this study, the quality of HJC measurement was based on the joint gap error (JGE), which is the difference in global HJC between proximal and distal reference segments. The aims of the present study were to: (1) determine if JGE varies between pelvic and sacral referenced HJC for functional and anatomical methods, (2) investigate which functional calibration motion results in the lowest JGE and if the JGE varies depending on movement type (gait versus chair rise) and gender, and (3) assess whether the functional HJC calibration results in lower JGE than commonly used anatomical approaches and if it varies with movement type and gender. Data were collected on 39 healthy adults (19 males and 20 females) aged 14-50 yr old. Participants performed four hip "calibration" tests (arc, cross, star, and star-arc), as well as gait and chair rise (activities of daily living (ADL)). Two common anatomical methods were used to estimate HJC and were compared to HJC computed using a published functional method with the calibration motions above, when using pelvis or sacral cluster as the proximal reference. For ADL trials, functional methods resulted in lower JGE (12-19 mm) compared to anatomical methods (13-34 mm). It was also found that women had significantly higher JGE compared to men and JGE was significantly higher for chair rise compared to gait, across all methods. JGE for sacrum referenced HJC was consistently higher than for the pelvis, but only by 2.5 mm. The results indicate that dynamic hip range of movement and gender are significant factors in HJC quality. The findings also suggest that a rigid sacral cluster for HJC estimation is an acceptable alternative for relying solely on traditional pelvis markers.

Kalman filter detection of blinks in video-oculography: applications for VVOR measurement during locomotion.

A Kalman filter algorithm was implemented for automatic detection of blink artifacts in video-oculography (VOG) data, and a cubic spline used to patch the eliminated data. The algorithm was tested by randomly introducing artificial blinks into eye movement data and computing the errors introduced by the patches. We also computed visual vestibulo-ocular reflex (VVOR) gain and phase in healthy and vestibulopathic subjects during a locomotor task, before and after blink removal, to demonstrate the interpretive importance of eliminating blink artifacts. The error introduced by the patched data was small (0.50+/-0.32 degrees ) and within the resolution of head angle measurements. Comparison of gain and phase shift before and after removing blinks revealed that even when calculated values are within expected limits, coherence of the VVOR signal was significantly (p=0.003) lower prior to blink removal (0.51+/-0.37) compared to that after blink removal (0.92+/-0.08). Comparison of VVOR calculations between healthy and vestibulopathic subjects (after removal of blinks) revealed that vestibulopathic subjects had significantly decreased gains (p=0.018) and increased phase shifts (p=0.009): these results agree with data reported in literature. We conclude that the Kalman filter detection and cubic spline patching algorithms are useful tools for VOG and should enable reliable VVOR measurements during unconstrained, ecologically meaningful locomotor activities.

In vivo hip pressures during cane and load-carrying gait.

OBJECTIVE: To test the hypotheses that carrying a load reduces hip contact pressure ipsilateral to the load and that using a cane when carrying a load further reduces hip contact pressure. METHODS: A Moore-type endoprosthesis with 13 femoral-head pressure transducers was implanted in a human subject following a Garden III fracture. Hip contact pressures were measured during unaided, cane-aided, and load-carrying gait over two years. RESULTS: Relative to unloaded gait, contact pressures increased significantly when ipsilateral to the carried load. Using a contralateral cane when carrying the load reduced ipsilateral posterior-superior contact pressure; however, the hip contralateral to the load experienced significantly higher than normal pressures. CONCLUSIONS: Ipsilaterally carried loads may not always provide stress protection of the arthritic hip. Using a cane opposite to the load may aid in restoring normal pressures to the ipsilateral hip, but may expose the contralateral hip to a significant stress burden.

Vestibular rehabilitation outcomes: velocity trajectory analysis of repeated bench stepping.

OBJECTIVES: To quantify vestibular rehabilitation (VR) outcomes in patients with vestibulospinal reflex pathology (VSP) using a new technique, high curvature analysis (HCA), that measures space trajectory stability. METHODS: Twelve patients with VSP and 10 healthy controls performed a repeated stepping task in a motion analysis laboratory. Patients with VSP were tested before and after a 12 week VR program. Three dimensional whole body center of gravity (CG) was captured during repeated bench stepping trials (step up forward/step down backward), and the resulting horizontal plane CG velocity trajectories were analyzed using HCA. RESULTS: VSP patients were significantly less stable than healthy subjects prior to VR (P=0.022), but these differences disappeared following VR (P=0.148). The stability of the VSP patients during the stepping task at 3 months increased significantly from baseline values (P=0.013). CONCLUSIONS: Evaluating the efficacy of VR requires analysis techniques that are sensitive to changes in stability. We conclude that HCA can be used for assessing improvements in CG stability of VSP patients while performing a repeated bench stepping activity.

Analysis of postural perturbation responses.

People with cerebellar ataxia lack lower limb coordination and dissipate sway motion slowly and inefficiently after a posture perturbation. We report a practical and low-cost "human resonance frequency test" for both laboratory and clinical use to quantify progress in balance and cerebellar rehabilitation. We assumed that the center-of-pressure (COP) oscillation rate of decay following a standing posture perturbation is directly related to resonance frequency; a more rapidly dissipating COP oscillation about the position of equilibrium indicates, by definition, more efficient postural control. We hypothesized that following successful physical rehabilitation, people with cerebellar degeneration will have a faster rate of decay of the COP response to an external perturbation. Because the COP is modulated by a synergy of trunk and lower limb motion strategies, COP decay rate may be a useful measure of lower limb coordination in people with cerebellar ataxia. The method was applied to three subjects with cerebellar ataxia before and after rehabilitation; there was good agreement between the calculated COP decay rate and conventionally used gait stability parameters providing pilot data for this simple approach.

Mechanical energy analysis identifies compensatory strategies in disabled elders' gait.

Current concepts in disablement emphasize the importance of identifying mobility impairments in aging humans to enable timely intervention and, ultimately, prevent disability. Because mobility impairments are likely to result in compensatory movement strategies, recognizing and understanding those strategies may be critical in designing effective interventions for preventing disability. We sought to determine if mechanical energy methods are useful for identifying and understanding lower extremity compensatory movement strategies due to disabilities. Aleshinski's method was used to compute mechanical energy expenditure (MEE) and mechanical energy compensation (MEC) for the sagittal plane stance leg and low-back joints of healthy elders (HE) and disabled elders (DE) during preferred speed and paced (120 steps min(-1)) gait. DE subjects expended less ankle energy in late-stance and more low-back energy in mid-stance than did the HE subjects. When controlling for walking speed, the difference in ankle MEE disappeared, but mid-stance hip MEE was significantly higher for the DE subjects. Despite increased hip and low-back MEE, the DE subjects compensated hip and low-back muscles greater then HE subjects by increasing energy transferred into the pelvis, particularly when walking faster than their self-selected speed. Increased energy transfers into the pelvis during mid-stance may be a strategy used to assist in advancing and controlling the contralateral limb's swing phase. Increased trunk energy, however, may compromise dynamic stability and increase the risk of falling. We conclude that mechanical energy methods are useful for identifying and understanding compensatory movement strategies in elders with disabilities.

Cartilage and subchondral bone thickness distribution with MR imaging.

RATIONALE AND OBJECTIVES: The authors mapped articular cartilage (AC) and subchondral bone (SB) thicknesses in human acetabula in vitro by using magnetic resonance (MR) imaging and validated AC measurements by using light microscopy. MATERIALS AND METHODS: Left and right acetabula from a deceased patient who had undergone left hemiarthroplasty were imaged with fat-suppressed spoiled gradient-recalled acquisition in the steady state (repetition time = 55 msec, echo time = 15 msec, flip angle = 50 degrees, matrix = 256 x 256, field of view = 8 cm). AC and SB thickness maps were generated from image data by using analytic geometry, which enabled correction for thickness overestimation due to oblique sectioning. Cartilage bone plugs were extracted from the acetabula, and light microscopy was used to validate the thickness measurements obtained with MR imaging. RESULTS: Standard errors between thickness measurements obtained with MR imaging and light microscopy were 0.37 and 0.33 mm for the left and right AC, respectively, which is consistent with the voxel resolution of the MR imaging sequence (0.31 x 0.31 x 0.8 mm). SB thickness of the cartilage plugs could not be reliably measured with light microscopy and, therefore, could not be validated. Contour maps showed that SB thickness gradients were rapid and focal compared with the rather smooth gradients in AC thickness; however, thicker AC was accompanied by thicker SB for left (r2 = .261, P = .0001) and right (r2 = .308, P = .0001) acetabula. Average thickness differences between left and right acetabular AC and SB were 0.13 mm (P = .015) and 0.11 mm (P = .026), respectively. Although it was the operated hip that had thicker articular tissues, the differences were within the pixel resolution (< 0.31 mm). CONCLUSION: AC and SB thickness distribution can be accurately determined by combining noninvasive MR imaging and analytic geometry, which may also provide a means for quantitative, longitudinal assessment of focal AC defects.

Lifting strategy and stability in strength-impaired elders.

STUDY DESIGN: Ninety-six subjects underwent biomechanical analysis of freestyle box lifting. OBJECTIVES: To relate lifting strategy to lower extremity muscle strength and postural stability in functionally limited elders. SUMMARY OF BACKGROUND DATA: Back pain and postural instability in elders is rampant and poorly understood. Much of the literature on lifting relates to young subjects. METHODS: Lifting strategy for 91 functionally limited elders was classified by timing of peak power in the back and knee joints. Isometric hip and knee extensor strength and postural stability were compared among strategy classifications. Postural stability was analyzed by measuring center of gravity (CG) displacement during lifting. RESULTS: Three lift strategy groups were established: back-lift, or back dominant strategy (BDS); leg-lift, or leg dominant strategy (LDS); and leg-dominant back-first mixed strategy (LDB). Subjects with relatively strong hip and knee extensors used leg dominant strategy; subjects with relatively strong knee, but weak hip, extensors used leg-dominant back-first mixed strategy; and subjects with weak hip and knee extensors used back dominant strategy. Leg dominant strategy and leg-dominant back-first mixed strategy engendered less center of gravity displacement and thus were posturally more stable than the back dominant strategy. CONCLUSION: Subjects apparently chose their lift strategy based on their hip and knee extensor strength. Weaker elders using a less stable back dominant strategy could be susceptible to falls and subsequent long bone and vertebral body fractures. Clinicians could identify at-risk elders by muscle testing. Beyond emphasizing strength and endurance exercise in elderly patients, weak elders should be taught to use a leg dominant lifting strategy, or if they are not physically able, to use a combined back/leg strategy.

Predictors of perception of cognitive functioning in HIV/AIDS.

This is a descriptive, correlational study of the predictors of perceived cognitive functioning. The convenience sample of 728 nonhospitalized persons receiving health care for HIV/AIDS was recruited from seven sites in the United States. All measures were self-reported. Self-perception of cognitive functioning, the dependent variable, was composed of three items from the Medical Outcomes Study HIV scale: thinking, attention, and forgetfulness. Data related to age, gender, ethnicity, education, injection drug use, CD4 count, and length of time known to be HIV-positive were collected on a demographic questionnaire. The scale from the Sign and Symptom Checklist for Persons with HIV Disease was used to measure self-reported symptoms. Data were analyzed using hierarchical multiple regression analysis. Predictors of perception of cognitive functioning explained a total of 36.3% of the variance. Four blocks--person variables (1.5%) (age, gender, education, history of injection drug use), disease status (2.3%), symptom status (26.5%), and functional status (5.4%)--significantly contributed statistically to the total variance. Among those individuals who completed the questions related to depression (n = 450), 28% of the variance in cognitive functioning was explained by this variable. The findings in this multi-site study indicate that symptom status explained the largest amount of variance in perceived cognitive functioning. Early identification of cognitive impairment can result in appropriate clinical interventions in remediable conditions and in the improvement of quality of life.

A general computing method for spatial cartilage thickness from co-planar MRI.

Techniques for assessing cartilage thickness from planar magnetic resonance (MR) images have traditionally accounted for surface curvature only in the image plane. Many joints, such as the knee and hip, have significant curvature normal (transverse) to the image plane which results in overestimation of in-plane cartilage thickness measurements. We developed a generalized computing method for calculating spatial thickness distribution of joint cartilage from co-planar MR images which accounts for transverse surface curvature. We applied the technique using fat-suppressed SPGR (spoiled gradient recalled in the steady-state) MR images of two human acetabulae and compared the results with a previously validated spherical model of the acetabulum which also accounts for transverse curvature of the cartilage surface. The agreement between the generalized model and validated spherical model was very good for both acetabular specimens (correlation: r = 0.998, p < 0.001; differences: p > 0.63). We conclude that the generalized method is acceptable for computing spatial cartilage thickness distribution of joints with complex geometries, such as the knee.

Mechanical energy transfer during gait in relation to strength impairment and pathology in elderly women.

OBJECTIVE: To examine the relationships among strength impairment, pathology and the mechanical energy transfers across the leg and low-back joints in a sample of frail elderly women with functional limitations. BACKGROUND: Past studies suggest mechanical energy analyses may be useful for identifying compensatory strategies used by elders during gait, but also suggest that age and strength are not the only factors that determine the extent of compensatory strategy use. METHODS: Gait data for 75 functionally limited women 60-90 years of age were analyzed. Subjects were categorized by strength and pathology diagnoses. Inverse dynamics was used to compute concentric (positive) and eccentric (negative) mechanical energy expenditures of the ankle, knee, hip and low-back during the stance phase of gait. Joint mechanical energy expenditures were compared between strength and diagnoses groups, and relationships among joint mechanical energy expenditures examined within groups. RESULTS: Weaker subjects demonstrated lower concentric ankle and eccentric knee mechanical energy expenditures, and higher eccentric low-back mechanical energy expenditures, than stronger subjects. Subjects with orthopaedic impairments demonstrated higher eccentric low-back mechanical energy expenditures than subjects with other impairments. Inverse correlations were found between ankle mechanical energy expenditures and hip and low-back mechanical energy expenditures for subjects with orthopaedic impairments. CONCLUSIONS: Elders with weak leg muscles and orthopaedic impairments increased hip and low-back mechanical energy expenditures, apparently to compensate for reduced ankle and knee mechanical energy expenditures. Further research is warranted to determine what long-term influences these compensatory strategies have on function and disability. Relevance. Mechanical energy methods could be useful for developing rehabilitative training programs to eliminate mobility impairments and avoid disablement in frail elders.fs

Effects of age and functional limitation on leg joint power and work during stance phase of gait.

It is commonly accepted that leg muscle power is an important component of functional ability. Paced gait data for 20 healthy young women (27+/-4.2 yrs), 16 healthy old women (72.5+/-5.6 yrs), and 24 functionally limited old women (73.5+/-7.2 yrs) were analyzed during stance phase to investigate whether power calculations from motion analysis data were sensitive to impairments beyond the differences expected with aging. Healthy women included in the study functioned at a high/moderate level with no limitations, while functionally limited women functioned at a much lower level and exhibited one or more functional limitations as defined by the SF36 physical function scale. Single support time (SSUP), stance duration (SDUR), average forward center of gravity velocity (GVEL), and three-dimensional net power and work of the ankle (APOW/AWRK), knee (KPOW/KWRK), and hip (HPOW/ HWRK) were computed for the stance limb during the stance phase of gait. Univariate ANCOVA was used to examine which variables were most sensitive to functional limitations. We found that SDUR and SSUP were not different among the three groups when controlling for height and weight. Although differences in CG velocity between healthy and functionally limited old women were not significant, both elderly groups translated their CG slower than did the younger women (p<0.0001) when walking at the same cadence. Controlling for CG velocity eliminated all significant differences among groups except for APOW and AWRK in late stance phase between healthy and functionally limited elderly women (p<0.003). These results suggest that decreased ankle plantar-flexor power in late stance of gait may be an impairment-related characteristic more than an age-related characteristic.

Vestibulopathy and age effects on head stability during chair rise.

It is unknown how vestibular dysfunction and age differentially affect balance control during functional activities. The objective of this study was to gain insight into the effects of age and vestibulopathy on head control when rising from a chair. Head relative to trunk (head-on-trunk) sagittal plane angular and linear control strategies were studied in patients with bilateral vestibular hypofunction (BVH) and in healthy subjects aged 30-80 years. A two-way analysis of variance was used to compare head-on-trunk kinematics by age (young vs elderly) and diagnosis (healthy vs BVH) at the time of liftoff from the seat. Angular control strategies differed with age but not diagnosis: young (healthy and BVH) subjects stabilized head rotations in space while elderly (healthy and BVH) subjects stabilized head rotations on the trunk. In contrast, linear control strategies differed by diagnosis but not age: BVH subjects (young and old) allowed a greater rate of head-on-trunk translation while healthy subjects (young and old) inhibited such translations. Young BVH subjects stabilized head-in-space rotations (as did young healthy subjects) without a functioning vestibular system, suggesting cervicocollic reflex and/or other sensory compensation for vestibular loss. Elderly BVH subjects stabilized head rotation with respect to the trunk, as did healthy elders, but did not stabilize head-on-trunk translations, suggesting a reliance on passive mechanical responses of the neck to sense head movements. We conclude that compensation strategies used by patients with vestibulopathy are age-dependent and appear to be more tractable in the younger BVH patient.

Lifting characteristics of functionally limited elders.

BACKGROUND: The purpose of this study was to investigate the lifting characteristics of elders with functional limitations using burden lifting smoothness, trunk angular momentum, and back and hip torque, and to correlate these characteristics with strength and functional measures. METHODS: Thirty elders (65-89 years old) consented to biomechanical analysis of lifting, gait, and chair rise, and to maximum isometric strength testing of the hip and knee extensors and shoulder flexors. Jerk, the rate of change of acceleration, is a measure of smoothness of motion. We calculated peak vertical jerk of the box at the beginning part of the lift. Momentum is the product of mass and velocity. HAT (head, arms, trunk) angular momentum was calculated during chair rise. RESULTS: Hip extensor strength correlated positively with box jerk, as did box jerk and peak trunk angular momentum between subjects. There was an inverse correlation between peak upper body angular momentum when lifting a box from floor to knee height, and gait speed normalized to body weight. There was a positive correlation between trunk angular momentum during lifting and trunk angular momentum during chair rise. CONCLUSION: Stronger subjects used more peak vertical box jerk and more trunk peak angular momentum to lift a box from floor to knee height. Stronger subjects who used more HAT angular momentum during free speed chair rise also used more trunk peak angular momentum during the first phase of the lift, but lifting characteristics were independent of gait velocity. Weaker subjects used less peak momentum and peak jerk, choosing instead a more conservative, and apparently more stable, lifting strategy. Before counseling elderly patients on proper body mechanics for lifting, clinicians should assess strength and functional status. Weak elders should be taught a lifting strategy that allows them to maintain optimal balance, and to lift without jerking the load.

Associations between adult and child bicycle helmet use.

PURPOSE: To observe the incidence of proper and improper use or non-use of bicycle helmets by children and adults when riding bicycles in groups. STUDY DESIGN: An observational survey of bicycle riders on a recreational bicycle path. METHODS: In eight half-day sessions, two observers independently rated all riders in groups that consisted of adults and children either wearing or not wearing helmets. Those who wore helmets were then rated as wearing them properly or improperly. RESULTS: Two-thirds of children wore helmets, but less than one-half wore them properly. One third of the adults wore helmets, and one-half of those wore them properly. Adult helmet use affected child helmet negatively. The strongest correlations were between adult helmet use or non-use and improper or no helmet use in accompanying children. CLINICAL IMPLICATIONS: Primary care nurses who work with healthy populations should collaborate with other groups involved with families to not only exhort them to wear helmets when riding bicycles but also to instruct those riders how to wear their helmets properly.

Age-related changes in lower trunk coordination and energy transfer during gait.

The effects of aging on lower trunk (trunk-low-back joint-pelvis) coordination and energy transfer during locomotion has received little attention; consequently, there are scant biomechanical data available for comparison with patient populations whose upper body movements may be impaired by orthopaedic or neurologic disorders. To address this problem, we analyzed gait data from a cross-sectional sample of healthy adults (n = 93) between 20 and 90 yr old (n = 44 elderly, >50 yr old; n = 49 young, <50 yr old). Gait characteristics of elders were mostly typical: gait speed of elders (1.13 +/- 0.20 m/s) was significantly (P = 0.007) lower than gait speed of young subjects (1.20 +/- 0.18 m/s). Although elders had less low-back (trunk relative to pelvis) range of motion (ROM; P = 0.013) during gait than young subjects, no age-related differences were detected in absolute trunk and pelvis ROM or peak pitch angles during gait. Despite similar upper body postures, there was a strong association between age and pelvis-trunk angular velocity phase angle (r = 0.48, P < 0.001) with zero phase occurring at approximately 55 yr of age; young subjects lead with the pelvis while elderly subjects lead with the trunk. Age related changes in gait speed and low-back ROM were unable to explain the above findings. The trunk-leading strategy used by elders resulted in a sense reversal of the low-back joint power curve and increased (P = 0.013) the mechanical energy expenditure required for eccentric control of the lower trunk musculature during stance phase of gait. These data suggest an age-related change in the control of lower trunk movements during gait that preserves upper body posture and walking speed but requires a leading trunk and higher mechanical energy demands of lower trunk musculature-two factors that may reduce the ability to recover from dynamic instabilities. The behavioral and motor control aspects of these findings may be important for understanding locomotor impairment compensations in aging humans and in quantifying falls risk.

Comparison of hip center estimation using in-vivo and ex-vivo measurements from the same subject.

OBJECTIVE: To evaluate the accuracy of locating the hip center (HIPC) by comparing in-vivo estimations to posthumous HIPC measurement in the same subject. BACKGROUND: Numerous techniques have been used to locate the HIPC in living subjects and in cadavers. There are no published reports, however, which have compared measurements of the HIPC obtained in-vivo and ex-vivo for the same subject. DESIGN AND METHODS: Bilateral hip centers (HIPC) were estimated for an elderly male patient seven times over 32 months in a gait laboratory using a technique which combines kinematic data and static pointing. The patient's pelvis was recovered posthumously and analytical photogrammetry used to estimate the HIPC locations. Published methods which scale anatomical measurements to locate the HIPC were compared to our ex-vivo and in-vivo measurements. RESULTS: HIPC precision was 0.94 cm for the in-vivo measurements (N = 7 trial days) and 0.15 cm for the ex-vivo measurements (N = 6 photogrammetry trials). The resultant error between ex-vivo and in-vivo estimates of HIPC position was 1.17 cm. Resultant errors in locating the HIPC using published anatomical scaling factors ranged between 1.48 cm and 5.37 cm. CONCLUSIONS: Although we have been unable to compare in-vivo and ex-vivo HIPC measurements for more than one subject, results of our analysis suggest that using anatomical scaling to locate the HIPC may result in unsatisfactory subject-specific estimates of the HIPC.

High curvature and jerk analyses of arm ataxia.

We investigated high curvature analysis (HCA) and integrated absolute jerk (IAJ) for differrentiating healthy and cerebellopathy (CB) patients performing pointing tasks. Seventeen CB patients and seventeen healthy controls were required to move a pointer at their preferred pace between two 50.8 cm laterally spaced targets while standing with theirarm extended in front of their body. HCA was used to quantify the frequency of sharp turns in the horizontal-plane (anterior-posterior and medio-lateral) velocity trajectory of the hand-held pointer. IAJ was assesssed by integration of absolute jerk (second time derivative of velocity) time histories in the anterior-posterior and medio-lateral directions. HCA scores and IAJ scores were then compared between CB patients and healthy controls; for both analyses, higher scores indicateless smooth movements. We hypothesized that CB patients would have less smooth movement trajectories than healthy controls due to upper extremity ataxia asssociated with cerebellar disease and degeneration. We found that CB patients had higher HCA scores than healthy controls (P = 0.014). Although CB patients had higher IAJ scores in both anterior-posterior (P = 0.060)and medio-lateral (P = 0.231) directions compared to the healthy controls, the differences were not significant. The difference in sensitivity between the HCA andthe IAJ analysis might be explained by primitive neural activation commands, ubiquitous though only evident with some cerebellar dysfunctions, which produce submovements which are themselves minimal jerk curves. We conclude that HCA may be a useful tool for quantifying upper extremity ataxia in CB patients performing a repeated pointing task.

The contribution of type of daily activity to loading across the hip and knee joints in the elderly.

OBJECTIVE: In the elderly, we evaluated loading across the hip or knee joints during different daily activities. METHODS: Elderly people drawn from the community entering an exercise study underwent a full kinetic and kinematics analysis of five different activities, standing, walking, arising from a chair, going downstairs and bending over. Inverse dynamic equations were used to compute forces and torques across the knees and hips during all of these activities. RESULTS: 132 elderly people, mean age 75, participated. Compressive forces across the knees and hips were, by far, the greatest vector forces and were highest during stair descent and, to a lesser extent, during walking. Compressive forces were lowest during standing. The highest moments were flexion and adduction moments, and these were maximal during stair descent. CONCLUSION: Of the five activities we studied, descending stairs was associated with the highest calculated forces and torques across the knees and hips, and that may account for its tendency to cause joint symptoms and for its possible association with osteoarthritis incidence.

The use of complementary and alternative therapies.

The National Center for Complementary and Alternative Medicine (NCCAM) was created by Congress in 1998 as part of the National Institutes of Health. As interest in alternative and complementary therapies among healthcare providers and consumers has increased in recent years, the NCCAM has provided research funding to determine the efficacy of various types of unconventional treatments. The Center also provides research training and acts as a clearing-house for information dissemination to practitioners and the general public. Inclusion and exclusion criteria for alternative and complementary medicine as defined by the NCCAM are provided. Interest in these non-traditional treatments will likely continue to increase over the next few years. The NCCAM is playing a vital role as it provides avenues to determine how these therapies can lead to enhanced quality of life for individuals as we enter the new millennium.