Lower Extremity Activity Research Articles

Gait patterns during different walking conditions in older adults with and without knee osteoarthritis—Results from the Baltimore Longitudinal Study of Aging

Biomechanical analysis of lower extremity activities while walking at different speeds and in challenging conditions may help to identify specific gait patterns associated with knee osteoarthritis (knee-OA). We hypothesized that individuals with asymptomatic knee-OA have lower ankle activity, while individuals with symptomatic knee-OA have similar or higher ankle activity compared to individuals without knee-OA, and that such differences are enhanced during challenging gait tasks. We tested this hypothesis by examining gait characteristics in multiple gait tasks using data from 153 Baltimore Longitudinal Study of Aging (BLSA) participants (112 without knee-OA, 41 with knee-OA; 53–87 years, 52% women). All participants who could walk unassisted were evaluated in the BLSA gait lab while walking at self-selected speed (usual-walking), at maximum speed (fast-walking) and again at self-selected speed after 30-min of walking activities (usual-walking-after-30min). Knee range of motion was lower for knee-OA participants in the fast-walking and usual-walking-after-30min tasks (p<0.030). Ankle range of motion for symptomatic knee-OA was greater compared to asymptomatic knee-OA for all walking tasks (p<0.050). Symptomatic knee-OA had greater generative MWE of the ankle compared to asymptomatic knee-OA (p=0.034), while keeping similar absorptive MWE of the knee when compared to no-OA controls (p=0.151). Symptomatic knee-OA individuals seem to adapt an ankle kinematic gait pattern aimed at avoiding knee pain, by enhancing forward propulsion so to minimize knee joint load. Whether these conditions represent subsequent steps in the causal pathway from knee-OA to changes in gait is still not clear.

Factors That Impact Expectations Before Total Knee Arthroplasty

This study examined the effect of patient attributes on expectations before total knee arthroplasty (TKA). A total of 1943 patients completed an Expectations Survey before TKA. Demographics, surgical history, baseline Medical Outcomes Study Short Form 36 (SF-36) score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Lower Extremity Activity Scale score were obtained. On univariate analysis, expectations (mean score, 77.6) correlated with SF-36 General Health, age, SF-36 Vitality, KOOS Quality-of-Life, and Lower Extremity Activity Scale. Living alone and history of joint arthroplasty were associated with significantly lower expectations, whereas male sex and white race were associated with higher expectations. On multivariate regression analysis, age, living situation, history of joint arthroplasty, SF-36 General Health, and KOOS Quality-of-Life remained significant predictors of expectations. Our results suggest that high, possibly unrealistic, expectations of TKA are common and should be moderated to maintain patient satisfaction.

Modular Femoral Stems for Revision Total Hip Arthroplasty

Modular femoral stems are one option for revision THA surgeons and allow offset restoration, leg length discrepancy correction, and stability independent of distal stem fixation. The complexity of revision THA usually leads surgeons to use multiple revision hip designs to address these issues. We evaluated functional outcomes with a revision modular system and determined whether such a system achieved initial distal fixation, femoral offset restoration, leg length equalization, and hip stability. We prospectively followed 118 patients in whom a modular stem system was used for reconstruction of their failed index femoral stem. Sixty-nine hips were classified as Type I (classification of Paprosky et al.), 35 as Type II, 17 as Type III, and one as Type IV. Functional assessment was achieved using patient- and physician-administered outcome evaluations (SF-36, WOMAC, Lower Extremity Activity Scale, Harris hip score). Stem fixation, offset restoration, leg length discrepancy, and hip stability were evaluated radiographically. Complications were also recorded. Minimum followup was 2 years (average, 4 years; range, 2-7 years). Average values on all functional outcome evaluations showed improvement at latest followup. Distal bone ingrowth fixation was obtained in 100% of the patients, offset was corrected in 66%, leg length discrepancy was corrected in 78%, and stability was achieved in 97%. No failures or fractures at the body to stem junction were seen at latest followup. Modular femoral components achieved functional outcomes and were useful to address distal fixation, femoral offset restoration, leg length equalization, and hip stability when revising failed femoral components. Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Stabilizing function of the diaphragm: dynamic MRI and synchronized spirometric assessment

The aim was to describe diaphragmatic behavior during postural limb activities and examine the ventilatory and stabilizing functions of the diaphragm. Thirty healthy subjects were examined in the supine position using a dynamic MRI system assessed simultaneously with specialized spirometric readings. The diaphragmatic excursions (DEs) were measured at three diaphragmatic points in the sagittal plane; the diaphragm positions (DPs) as related to a reference horizontal baseline were determined. Measurements were taken during tidal breathing (TB) and isometric flexion of upper or lower extremities against external resistance together with TB. Mean DE in both upper and lower postural limb activities was greater compared with the TB condition (P < 0.05), with the effect greater for lower limb activities. Inspiratory DPs in the upper and lower extremity activities were lower compared with TB alone (P < 0.01). Expiratory DP was lower only for lower extremity activities (P < 0.01). DP was most affected at the apex of the crescent and crural (posterior) portion of the diaphragm. DEs correlated strongly with tidal volume (Vt) in all conditions. Changes in DEs relative to the initial value were minimal for upper and lower extremities but were related to lower values of Vt (P < 0.03). Significant involvement of the diaphragm in the limb postural activities was found. Resulting DEs and DPs differed from the TB conditions, especially in lower extremity activities. The differences between the percent changes of DEs vs. Vt found for lower extremity activities were confirmed by both ventilatory and postural diaphragm recruitment in response to postural demands.

Patterns of Functional Improvement After Revision Knee Arthroplasty

Despite the increase in the number of total knee arthroplasty revisions, outcomes of such surgery and their correlates are poorly understood. The aim of this study was to characterize patterns of functional improvement after revision total knee arthroplasty over a two-year period and to investigate factors that affect such improvement patterns. Three hundred and eight patients in need of revision surgery were enrolled into the study, conducted at seventeen centers, and 221 (71.8%) were followed for two years. Short Form-36 (SF-36), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Lower-Extremity Activity Scale (LEAS) scores were collected at baseline and every six months for two years postoperatively. A piecewise general linear mixed model, which models correlation between repeated measures and estimates separate slopes for different follow-up time periods, was employed to examine functional improvement patterns. Separate regression slopes were estimated for the zero to twelve-month and the twelve to twenty-four-month periods. The slopes for zero to twelve months showed significant improvement in all measures in the first year. The slopes for twelve to twenty-four months showed deterioration in the scores of the WOMAC pain subscale (slope = 0.67 +/- 0.21, p < 0.01) and function subscale (slope = 1.66 +/- 0.63, p < 0.05), whereas the slopes of the other measures had plateaued. A higher number of comorbidities was consistently the strongest deterrent of functional improvement across measures. The modes of failure of the primary total knee arthroplasty were instrument-specific predictors of outcome (for example, tibial bone lysis affected only the SF-36 physical component score [coefficient = -5.46 +/- 1.91, p < 0.01], while malalignment affected both the SF-36 physical component score [coefficient = 5.41 +/- 2.35, p < 0.05] and the LEAS score [coefficient = 1.42 +/- 0.69, p < 0.05]). Factors related to the surgical technique did not predict outcomes. The onset of worsening pain and knee-specific function in the second year following revision total knee arthroplasty indicates the need to closely monitor patients, irrespective of the mode of failure of the primary procedure or the surgical technique for the revision. This information may be especially important for patients with multiple comorbidities.

Using pedometers to monitor walking activity in outcome assessment for pulmonary rehabilitation

The purpose of this study was to determine whether a commercially available pedometer could detect changes in home-based walking activity among chronic obstructive pulmonary disease (COPD) patients completing pulmonary rehabilitation (PR). Patients with COPD referred to outpatient PR wore a pedometer to count steps for 1 week at the beginning and 1 week at the end of PR. Patients also completed the 6-min walk test (6MWT), the Medical Research Council (MRC) dyspnea scale and the self-administered chronic respiratory disease questionnaire (CRQ) at the beginning and the end of PR. Paired t tests were used to compare pre- and post-PR changes in outcome variables. 45 patients with severe COPD (forced expiratory volume in 1 second [FEV(1)] 45% +/- 18% of predicted) participated in a total of 17.4 +/- 4.6 PR sessions. Significant improvements in 6MWT (49 +/- 59 m; p < .0001), MRC dyspnea score (-0.64 +/- 0.96 units; p = .003) and CRQ score (10 +/- 18 units; p = .0007) were noted following PR. Patients whose pedometer-measured steps were within 20% of observed counted steps were included in the analysis. Pedometer counts increased by 33 +/- 149 steps per hour worn after, as compared with before PR (p = .14). There was a significant inverse relationship between baseline pedometer counts and change in pedometer counts per hour post-PR (r = -.46; p = .001). Patients with low baseline activity levels had significant increases in pedometer activity (88 +/- 30 counts per hour worn) and a greater reduction in MRC dyspnea score (-0.94 vs -0.29; p = .04) following PR, whereas those with higher baseline activity levels had a decrease in pedometer activity (-19 +/- 29 counts/hour; p = .015). A standard pedometer worn at the waist did not detect changes in lower extremity activity following PR. This negative finding occurred despite demonstrated improvements in dyspnea, exercise tolerance and quality of life measures. Although pedometers are inexpensive and easy to use, they may not be sensitive enough to be used routinely as an outcome measure for PR.

Effect of Total Knee Arthroplasty on Metabolic Syndrome

The purpose of this study was to evaluate the effect of changing activity after total knee arthroplasty (TKA) on metabolic syndrome with a follow-up period of 2 years. Two hundred consecutive patients who were to undergo TKA were prospectively enrolled. The patients' blood pressure, fasting plasma glucose level, the lipid profile, the waist circumference, the Knee Society score, and the Lower Extremity Activity Scale were measured preoperatively and at the 2-year follow-up visit. The data from 169 patients were finally collected and reviewed. Two years after primary TKA, there was no change in the prevalence of metabolic syndrome, despite that the patients had a significant increase of their physical activity.

Approaches to the improvement of the efficiency of rehabilitation of patients with chronic venous insufficiency of the lower extremities

The relationship between functional incompetence, development and severity of chronic venous insufficiency of the lower extremities was investigated by the method of clinical analysis of locomotor activity. Results of the study may be used to choose an optimal therapeutic modality and assess dynamics of its efficiency. It was shown that the treatment of chronic venous insufficiency in the majority of the patients is inefficient unless functional activity of the lower extremities is recovered. Stimulation of the muscular-venous pump improves the outcome of postoperative rehabilitation, permits to reduce its duration, and improves quality of life of the patients.

Effects of glucocorticoid treatment on the functional capacity of stem cell transplant recipients entering a rehabilitation program

7104 Background: Emerging data strongly supports the concept that stem cell transplant (SCT) recipients derive psychological and physiological benefit from participation in exercise training programs. Many SCT recipients receive glucocorticoids (GC) for prolonged periods, increasing their risk for proximal muscle damage and raising the possibility that SCT recipients on GC may differ from those SCT recipients not receiving GC in terms of their exercise/functional capacity. This becomes an important reconditioning issue because exercise prescription and progression is predicated on initial exercise capacity. Therefore the purpose of this study was to compare the initial functional capacity of outpatient STC recipients receiving GC to STC recipients not receiving GC. Methods: The medical records of 163 successive SCT recipients referred to Rehabilitation Services for reconditioning were retrospectively reviewed for demographic information and measures of exercise/functional capacity (6-min walk test, 50-ft fast walk, and repeated sit-to-stand times) collected at the initial physical therapy visit. Data from SCT recipients on GC (ON) were compared with that of SCT recipients not on GC (OFF) by means of an unpaired t-test (α=0.05). Data are presented as mean + standard deviation. Results: Demographic and functional measures are presented in the following tables. Significant differences between group means are denoted by an asterisk. Conclusions: STC recipients on steroids have comparable endurance capacity to those STC recipients not on steroids, but are less capable of performing lower extremity activities requiring rapid movement and receive rehabilitation services later in the post transplant recovery course. These results suggest rehabilitation strategies are 1) needed for STC patients, 2) should be individualized according to the patient's drug regime, and 3) should be initiated soon after the stem cell transplant. [Table: see text] No significant financial relationships to disclose.

Early Discharge and Recovery with Three Minimally Invasive Total Hip Arthroplasty Approaches: A Preliminary Study

Purported advantages of THA performed with minimally invasive surgical approaches include less muscle damage and faster recovery. The purpose of this preliminary investigation was to determine if differences existed between minimally invasive approaches in hospital discharge and early functional recovery in THA patients with a rapid rehabilitation protocol. Twenty-four consecutive patients were randomized to one of three minimally invasive surgical approaches (two-incision, mini-posterior, and mini-anterolateral) and enrolled in an aggressive postoperative rehabilitation program. Hospital discharge, early functional milestone recovery, and validated outcome measures (SF-36, WOMAC, Harris hip score, lower extremity activity scale) were collected. All patients met hospital discharge criteria no later than the first postoperative day. There was no difference in hospital discharge, functional milestone recovery, or validated outcome measures during the first year after surgery with the numbers available. There were no complications directly related to early hospital discharge or the aggressive rehabilitation protocol. While the data suggest earlier hospital discharge and rapid rehabilitation protocols may be implemented successfully we found no difference between the three minimally invasive approaches in early hospital discharge or early functional recovery utilizing a rapid rehabilitation protocol. Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Weight and Activity Change in Overweight and Obese Patients After Primary Total Knee Arthroplasty

Few studies have examined the effect of primary total knee arthroplasty on the weight and physical activity of overweight and obese patients in the United States. We conducted a prospective study of changes in mean weight, body mass index (BMI), and physical activity over 2 years in 188 consecutive overweight or obese patients. Weight, BMI, and physical activity, evaluated using the Lower Extremity Activity Scale (LEAS), were assessed preoperatively and at 1 and 2 years. At 2 years, no significant weight change was found (P = .80), but BMI increased by 0.46 kg/m2 (P = .049). The LEAS score increased from preoperatively to 2 years (P < .001). Preoperative LEAS score was not associated with weight or BMI at 2 years. This finding has implications for patient expectations and preoperative counseling.

Evaluating the Performance of Lower Extremity Activity with Slope-Adjustable Systems

Evaluating the Performance of Lower Extremity Activity with Slope-Adjustable Systems

Measuring patients’ perceptions on their functional abilities: validation of the Haemophilia Activities List

Recently, the Haemophilia Activities List (HAL), a haemophilia-specific self-assessment questionnaire to assess a patient's self-perceived functional ability, was introduced and a limited pilot study warranted its further development. The present study finalizes the HAL and assesses the convergent and construct validity, as well as the internal consistency of its definitive version. Three questionnaires (HAL, Dutch-Arthritis Impact Measurement Scales 2 and the Impact on Participation and Autonomy questionnaire) were completed by 127 patients with severe haemophilia (<1% clotting activity), as well as four performance tests (button test, 50 metre walking test, timed-up-and-go test and figure-8 walking test). After removal of 15 non-informative items from the provisional HAL, three components within the questionnaire were identified (upper extremity activities, basic lower extremity activities and complex lower extremity activities). The internal consistency of these components was high (Cronbach's alpha = 0.93-0.95), as was internal consistency for the seven domains of the HAL (alpha = 0.61-0.96). The convergent validity of the HAL when compared to the other two questionnaires was good (r = 0.47-0.84). The construct validity of the HAL when compared to the four performance tests was generally lower (r = 0.23-0.77). The final version of the HAL has good internal consistency and convergent validity and gives the clinician insight into a patient's self-perceived ability to perform activities of daily life. It is likely that self-assessment instruments (questionnaires) and performance tests consider different concepts of functional health status and it is therefore recommended that both types are included when clinicians assess a patient's functional abilities.

Development and Validation of a Lower-Extremity Activity Scale

Valid outcome measurement tools are required to reliably demonstrate the effectiveness and clinical outcomes of lower-extremity arthroplasty. Having ascertained a lack of a practical and valid measure of the change in actual daily physical activity that occurs prior to and following lower-limb arthroplasty, we developed and validated a lower-extremity activity scale. The eighteen-level self-administered scale was developed with the aid of content experts to ensure face validity. Validity and reliability were assessed with the use of (1) pedometer measurements of seventy subjects over seven days; (2) next-of-kin proxy measurements of the activity levels of ninety patients before they underwent lower-limb arthroplasty; and (3) application, and correlation with the Western Ontario and McMaster Universities Osteoarthritis Index scores, in a prospective seventeen-center clinical study of 297 consecutive patients undergoing revision total knee arthroplasty. In this latter study, demographic and comorbidity data were also collected. Univariate and bivariate correlations were performed, and a multivariate structured equation modeling approach was used to further test responsiveness, reliability, and validity of the lower-extremity activity scale. Pedometer readings correlated with the activity levels derived with the lower-extremity activity scale (r = 0.79). Of note was the finding that age, weight, and body mass index did not correlate well with the average number of steps per day (r = -0.32, -0.32, and -0.25, respectively). A significant correlation was found between the lower-extremity activity scores recorded by the patients and those reported by their next of kin (Pearson correlation, r = 0.715; p = 0.0001) and between the initial lower-extremity activity scores and two-week-retest scores (intraclass correlation = 0.9147; p < 0.0001), demonstrating the validity and reliability of the scale. The lower-extremity activity scale was responsive, accurately reflecting changes in the patient's condition between baseline and the time of follow-up (p < 0.001), and it was reliable, with baseline values correlating with follow-up scores (p < 0.001). The convergent validity of the lower-extremity activity scale was established by correlations with the function scores (r = -0.301, p < 0.001) and pain scores (r = -0.241, p < 0.001) derived with the Western Ontario and McMaster Universities Osteoarthritis Index and with a higher number of comorbidities (r = -0.244, p < 0.001). Multivariate path modeling further demonstrated diminished activity in patients who had more difficulty in functioning and a greater number of comorbidities. We developed a lower-extremity activity scale and validated that it was an effective instrument for the assessment of patients' actual activity levels. It is easy to apply and interpret, and it is valid and ready for use in the clinical setting. This scale will allow more accurate analysis and prediction of outcomes. Consequently, it will become a useful, practical adjunct to objective clinical decision-making and intervention for patients undergoing arthroplasty.

DEVELOPMENT AND VALIDATION OF A LOWER-EXTREMITY ACTIVITY SCALE

Background: Valid outcome measurement tools are required to reliably demonstrate the effectiveness and clinical outcomes of lower-extremity arthroplasty. Having ascertained a lack of a practical and valid measure of the change in actual daily physical activity that occurs prior to and following lower-limb arthroplasty, we developed and validated a lower-extremity activity scale. Methods: The eighteen-level self-administered scale was developed with the aid of content experts to ensure face validity. Validity and reliability were assessed with the use of (1) pedometer measurements of seventy subjects over seven days; (2) next-of-kin proxy measurements of the activity levels of ninety patients before they underwent lower-limb arthroplasty; and (3) application, and correlation with the Western Ontario and McMaster Universities Osteoarthritis Index scores, in a prospective seventeen-center clinical study of 297 consecutive patients undergoing revision total knee arthroplasty. In this latter study, demographic and comorbidity data were also collected. Univariate and bivariate correlations were performed, and a multivariate structured equation modeling approach was used to further test responsiveness, reliability, and validity of the lower-extremity activity scale. Results: Pedometer readings correlated with the activity levels derived with the lower-extremity activity scale (r = 0.79). Of note was the finding that age, weight, and body mass index did not correlate well with the average number of steps per day (r = -0.32, -0.32, and -0.25, respectively). A significant correlation was found between the lower-extremity activity scores recorded by the patients and those reported by their next of kin (Pearson correlation, r = 0.715; p = 0.0001) and between the initial lower-extremity activity scores and two-week-retest scores (intraclass correlation = 0.9147; p < 0.0001), demonstrating the validity and reliability of the scale. The lower-extremity activity scale was responsive, accurately reflecting changes in the patient's condition between baseline and the time of follow-up (p < 0.001), and it was reliable, with baseline values correlating with follow-up scores (p < 0.001). The convergent validity of the lower-extremity activity scale was established by correlations with the function scores (r = -0.301, p < 0.001) and pain scores (r = -0.241, p < 0.001) derived with the Western Ontario and McMaster Universities Osteoarthritis Index and with a higher number of comorbidities (r = -0.244, p < 0.001). Multivariate path modeling further demonstrated diminished activity in patients who had more difficulty in functioning and a greater number of comorbidities. Conclusions: We developed a lower-extremity activity scale and validated that it was an effective instrument for the assessment of patients' actual activity levels. It is easy to apply and interpret, and it is valid and ready for use in the clinical setting. This scale will allow more accurate analysis and prediction of outcomes. Consequently, it will become a useful, practical adjunct to objective clinical decision-making and intervention for patients undergoing arthroplasty.

Bilateral Comparison Of Knee Flexion-extension Isokinetic Strength In Soccer Players

Clinicians often use isokinetic strength testing as a part of return to activity criteria, which are commonly based on the strength exhibited by the injured extremity compared to that of the uninjured extremity. This would be a valid standard assuming no strength differences exist between limbs. However, soccer athletes usually have tendencies to use one leg more than the other making the sport an asymmetrical lower extremity activity. If bilateral strength differences exist, then appropriate adjustments should be made for return to activity standards. PURPOSE To bilaterally compare isokinetic knee extension and flexion strength in experienced soccer players. METHODS Five females (age 20.0 ±0.7 yrs, height 164.1 ±4.53 cm, weight 635.9 ±30.7 N, competitive soccer 7.2±3.8 yrs experience) and 10 males (22.1 ±2.7 yrs, 169.5±12.0 cm, 712.6±153.6 N, 6.3±3.3 yrs), who were free of lower extremity injuries for at least 6 months prior to testing, participated in this study. Knee extension/flexion torques were measured using a KinCom AP125 isokinetic dynamometer at speeds of 60 and 180°/s. Two trials of 3 reciprocal repetitions were conducted for each speed and the highest extension and flexion torques were used in subsequent statistical analyses. A paired 2-tailed t-test was performed on each peak torque (α = 0.05). RESULTS Peak extension torque at 60°/s for the dominant leg was significantly greater than the corresponding value for the non-dominant leg (Table 1). Fourteen of the 15 participants had greater peak extension torque at 60 °/s in the dominant leg compared to the non-dominant leg. If the outlier was excluded from the statistical analysis, the mean peak isokinetic torque for the dominant leg would be 150.1±33.3 Nm compared to the non-dominant mean peak torque of 137±27.9 Nm (p <.001).Table 1: Mean (SD) peak isokinetic torques (Nm) for dominant (D) and non-dominant (ND) legs.CONCLUSION It appears that soccer players possess significantly greater knee extension strength at low contraction speed in the dominant leg. However, further research is needed to confirm this conclusion.

THE RELATIONSHIP BETWEEN ACTIVITY AND IONS IN PATIENTS WITH METAL-ON-METAL BEARING HIP PROSTHESES

Background: Metal-metal bearings are frequently implanted in young, active patients. The relationship between patient activity and Co and Cr ion levels has not been scientifically investigated. Methods: Seven patient subjects with well-functioning metal-metal bearing hip prostheses and one control subject (no implants), all with normal renal function, were monitored during a two-week long activity protocol. Lower extremity activity was continuously assessed by a computerized, two-dimensional accelerometer (Step Activity Monitor; SAM). During the first week, subjects were requested to limit physical activity. Subjects then completed an hour-long treadmill test followed by a week where they were encouraged to be as physically active as possible. Serum Co and Cr ion levels and urine Cr levels were assessed at 10 different time points during these two weeks. Results: Regardless of activity, the serum ion levels for a given patient were essentially constant and there was no correlation between patient activity and serum or urine ion levels. A mean increase in activity of 28% (95% CI, 13 to 43%; SE, 6%) during the high-intensity activity week resulted in a mean decrease of 2.6% (95% CI, −14.2 to 8.9%; SE, 4.7%) in serum Co and a mean increase of 2.0% (95% CI, −5.3 to 9.3%; SE, 3.0%) in serum Cr. During the treadmill test, a mean activity increase of 1,621% (16-fold) (95% CI, 972 to 2,271%; SE, 265%) resulted in a mean increase of 3.0% (95% CI, −5.7 to 11.7%; SE, 3.6%) in serum Co and a mean increase of 0.8% (95% CI, −3.5 to 5.0%; SE, 1.7%) in serum Cr. This effectively constitutes no change in serum ion levels for these changes in activity because the differences are within the variability for the measurement accuracy of these tests. Conclusions: In patients with normal renal function and a well-functioning metal-metal bearing, ion levels are not affected by patient activity. Periodic measurements of serum ion levels can be used to monitor the tribologic performance of prosthesis with a metal-metal bearing without adjusting for patient activity.

The Relationship Between Activity and Ions in Patients with Metal-on-Metal Bearing Hip Prostheses

Total hip replacements with metal-on-metal bearings are frequently implanted in young, active patients. The relationship between patient activity and cobalt and chromium ion levels has not been investigated, to our knowledge. Seven patients with well-functioning metal-on-metal bearing hip prostheses and one control subject (no implants), all with normal renal function, were monitored during a two-week-long activity protocol. Lower-extremity activity was continuously assessed with use of a computerized, two-dimensional accelerometer. During the first week, the subjects were requested to limit physical activity. The subjects then completed an hour-long treadmill test followed by a week in which they were encouraged to be as physically active as practically possible. Serum levels of cobalt and chromium ions and urine levels of chromium were assessed at ten time-points during these two weeks. Regardless of activity, the serum ion levels for a given patient were essentially constant and no correlation was found between patient activity and serum levels of cobalt or chromium, or urine levels of chromium. A mean increase in activity of 28% during the week of high-intensity activity was associated with a mean decrease of 2.7% in the serum cobalt level and a mean increase of 2.0% in the serum chromium level. During the treadmill test, a mean increase in activity of 1621% was associated with a mean increase of 3.0% in the serum cobalt level and a mean increase of 0.8% in the serum chromium level. These results fall within the variability for the measurement accuracy of these tests. For these patients, serum cobalt and chromium ion levels were not acutely affected by patient activity. Periodic measurements of serum ion levels could be used to monitor the tribologic (lubrication, friction, and wear) performance of a metal-on-metal bearing without adjusting for patient activity. Additional research is needed into the kinetics of ion production, transport, and excretion.

Activity groupings reflecting functional characteristics required in daily life in institutionalized dependent females in the old old elderly group

This study aimed to determine the activity groupings reflecting functional characteristics required in daily life for the institutionalized dependent females in the old-old elderly group, by examining the interrelationships of activities based on actual achievement characteristics. The participants were 697 dependent elderly living at welfare institutions in Japan and 344 old-old females were used for analysis. Factor analysis, based on Promax with the Kaiser Normalization method, was conducted using 74 activities of daily living (ADL) items to determine activity groups. Furthermore, whether each activity group could be classified into sub-groups was confirmed by applying factor analysis to the activities consisting of each activity group. Four activity groups of lower extremity activities, manual activities, changing and holding posture activities, and upper extremity and dexterous manual activities were interpreted. Except for the manual activity group, these activity groups were classified into two sub-groups. These activity groupings were characterized by similarities of the body parts used in achievement and the difficulty of activity. The activity groupings obtained in this study are considered to be useful in ADL assessment focusing on evaluating functional characteristics of the dependent elderly.

The interrelationship among achievement patterns of activities of daily living for institutionalized dependent elderly.

The purpose of the present study was to examine the interrelationship of achievement patterns between 74 activities by selecting nine ADL domains, including 27 items used in existing ADL index for the institutionalized disabled elderly (Disabled-ADL). For these 74 ADL items, 706 institutionalized dependent elderly were assessed using a dichotomous scale of "possible" or "impossible" by staff working at the subjects' institutions. The difficulty of each item was examined by calculating the proportion of "possible" responses. The interrelationships among activities were determined by calculating phi coefficients. Furthermore, the degree of agreement assessed between ADL items was calculated by dividing the total response by the number of "possible-possible" and "impossible-impossible" responses, in order to examine the similarity of the achievement pattern of ADL. The phi coefficient values were high among ADL items with comparable difficulty where the item proportions were within about 10%. Even if belonging to a different ADL domain, the relationship was high among ADL items with similar difficulty and kinds of activity. All of the 27 activities used in Disabled-ADL indicated high agreement of over 80% with one or more activities among the other 47 activities used in this study. Especially, three lower extremity activities of "putting on trousers while standing", "going up and down stairs" and "squatting down from a standing posture" agreed more than 90% with many other lower extremity activities. The possibility is suggested in determining lower extremity functional levels by assessing these three activities. The selection of ADL items considering these influences is necessary to comprehensively assess ADL ability of disabled elderly.