Gait analysis in the rat as a model for the study of peripheral vascular disease

Improved gait parameters following surgical revascularization in patients with intermittent claudication

Objective

Intermittent claudication (IC) is known to be associated with impaired gait parameters, with a higher incidence of falls and higher oxygen consumption due to uneconomic walking. However, the influence of arterial disobliteration in patients with IC on their gait pattern has rarely been investigated to date. The aim of this study was to examine the gait patterns before and after inflow revascularization by surgical disobliteration of pelvic and inguinal arteries (ie, common iliac artery, external iliac artery, common femoral artery, profound femoral artery, superficial femoral artery) in IC patients. Successful surgical disobliteration of inflow arteries (improvement of ankle brachial pressure index of ≥0.2 and patent common iliac, external iliac, common femoral, profound femoral, and superficial femoral arteries) is known to improve the painless walking distance for patients with IC due to peripheral arterial disease; however, its influence on gait parameters is unclear. We hypothesized that the gait parameters would also improve after surgery. Improved gait parameters can lead to a more economic walking process, lower oxygen consumption, a lower risk of falls, and a higher quality of life.

Methods

In a single-center, exploratory, longitudinal study, we examined the gait parameters of 20 IC inpatients of our hospital before and after surgical disobliteration of pelvic and inguinal arteries. Spatiotemporal parameters such as range of motion of the hip and knee joint, stance phase, cadence, and foot rotation were obtained using the Diers 4Dmotion Lab (Diers International). The gait parameters were obtained under painful walking conditions preoperatively and with the patients walking pain free at the same speed postoperatively.

Results

A total of 20 patients were examined. Surgical revascularization led to a higher walking cadence (mean, plus 7.88 steps; 95.5 steps/min vs 87.6 steps/min; P = .024), an increased range of motion of the hip joint (mean, plus 2.0°; 35.1° vs 33.1°; P = .038), and improved foot rotation (mean, plus 2.0°; 11.0° vs 9.0°; P = .02). Regarding other parameters such as step length, stance phase, and step duration, smaller differences were detected in this study.

Conclusions

In this exploratory study, we found that surgical revascularization of pelvic and inguinal arteries in IC patients improved certain gait parameters. Further studies with larger patient numbers are needed to confirm these data and provide more evidence on this subject.

Quadrupedal rodent gait compensations in a low dose monoiodoacetate model of osteoarthritis

BACKGROUND

Rodent gait analysis provides robust, quantitative results for preclinical musculoskeletal and neurological models. In prior work, surgical models of osteoarthritis have been found to result in a hind limb shuffle-stepping gait compensation, while a high dose monoiodoacetate (MIA, 3 mg) model resulted in a hind limb antalgic gait. However, it is unknown whether the antalgic gait caused by MIA is associated with severity of degeneration from the high dosage or the whole-joint degeneration associated with glycolysis inhibition.

RESEARCH QUESTION

This study evaluates rodent gait changes resulting from a low dose, 1 mg unilateral intra-articular injection of MIA compared to saline injected and naïve rats.

METHODS

Spatiotemporal and dynamic gait parameters were collected from a total of 42 male Lewis rats spread across 3 time points: 1, 2, and 4 weeks post-injection. To provide a detailed analysis of this low dose MIA model, gait analysis was used to uniquely quantify both fore and hind limb gait parameters.

RESULTS

Our data indicate that 1 mg of MIA caused relatively minor degeneration and a shuffle-step gait compensation, similar to the compensation observed in prior surgical models.

SIGNIFICANCE

These data from a 1 mg MIA model show a different gait compensation compared to a previously studied 3 mg model. This 1 mg MIA model resulted in gait compensations more similar to a previously studied surgical model of osteoarthritis. Additionally, this study provides detailed 4 limb analysis of rodent gait that includes spatiotemporal and dynamic data from the same gait trial. These data highlight the importance of measuring dynamic data in combination with spatiotemporal data, since compensatory gait patterns may not be captured by spatial, temporal, or dynamic characterizations alone.

Collateral Vessel Formation Causes Clinical Recovery From Limb Ischemia in a Mouse Model

Experimental models of recovery from limb ischemia are required for evaluating novel means of treating ischemia. We describe a mouse model to assess gait after inducing limb ischemia. Gait analysis was performed using a Plexiglass tube, the floor of which contained load cells. Gait was measured in 20 mice; 10 underwent ligation of the right hind limb artery and the other 10 underwent a sham operation. The gait of the animals was measured at 1, 2, and 4 weeks following the procedure. In sham-operated animals, the gait showed no measurable change. In the ligated animals, the ratio of the right fore-to-hind limb changed from 1.07 at baseline to 1.4 at day 0 (P = .001), 1.16 (P = .012 compared with control), and 1.04 (P = .37 compared with control) at weeks 2 and 4, respectively. Gait returned to normal within 4 weeks of induction of ischemia. This model may be helpful in testing potential novel therapies.

Assessment of gait dynamics in rats submitted to limb ischemia

PURPOSE

To describe a method for the assessment of gait dynamics in rats submitted to limb ischemia.

METHODS

Twenty-four male Wistar rats (150-160g) were used. Twelve animals were submitted to limb ischemia by ligation of the common left iliac artery (ischemic group: n = 12); and a sham-operated group was used as control (n=12). After a recovery period of 6 weeks, gait dynamics was assessed by counting the complete footprints and the number of hindlimb-floor contacts during a treadmill test for five minutes at a speed of 12 m.min(-1) and angulation of 15°. The number of contacts of the left hindlimb was divided by the right hindlimb values (LRR) for group comparisons. Ischemic disability was quantified by comparing the area under curve (AUC) created by plotting each contact versus time for each hindlimb. The left hindlimb ischemic disability index (LHDI), which was compared between groups, was defined by the formula: LHDI = (1- AUC (left) / AUC (right)) x 100.

RESULTS

Surgery was well tolerated by all animals. Rats did not suffer tissue loss or ulcerations. Complete footprint LRR was 0.3 ± 0.08 for the ischemic group and 1.3 ± 0.9 for controls (p=0.0043). Number of contacts LLR was 0.5 ± 0.2 for the ischemic group and 1.0 ± 0.1 for the control group (p=0.0051). LHDI was 56.83 ± 10.67 for the ischemic group and 2.50 ± 13.10 for the control group (P = 0.031).

CONCLUSION

Assessment of gait dynamics in rats submitted to limb ischemia could be done by footprint analysis and hindlimb contact recording during a treadmill test.

The relationship between bone mechanical properties and ground reaction forces in normal and hypermuscular mice

Understanding the relationship between external load and bone morphology is critical for understanding adaptations to load in extant animals and inferring behavior in extinct forms. Yet, the relationship between bony anatomy and load is poorly understood, with empirical studies often producing conflicting results. It is widely assumed in many ecological and paleontological studies that bone size and strength reflect the forces experienced by the bone in vivo. This study examines that assumption by providing preliminary data on gait mechanics in a hypermuscular myostatin-deficient mouse model with highly mineralized and hypertrophied long bones. A small sample of hypermuscular and wild-type mice was video recorded while walking freely across a force platform. Temporal gait parameters, peak vertical and transverse (mediolateral) ground reaction forces (GRFs), vertical impulse, and loading rates were measured. The only gait parameters that differed between the two groups were the speeds at which the animals traveled and the transverse forces on the hind limb. The myostatin-deficient mice move relatively slowly and experienced the same magnitude of vertical forces on all limbs and transverse forces on the forelimb as the wild-type mice; though the myostatin-deficient mice did experience lower mediolateral forces on their hindlimbs compared with the wild-type mice. These preliminary results call into question the hypothesis that skeletal hypertrophy observed in hypermuscular mice is a result of larger GRFs experienced by the animals' limbs during locomotion. This calls for further analysis and a cautious approach to inferences about locomotor behavior derived from bony morphology in extant and fossil species.

Gait abnormalities differentially indicate pain or structural joint damage in monoarticular antigen-induced arthritis

Gait abnormalities have been suggested to provide an objective measure for joint pain in animal models. Here, we aimed to assess whether parameters of gait analysis correlate with measures of pain-related behavior in experimental monoarthritis. For this purpose, antigen-induced arthritis was induced in the left knee joints of 68 female Lewis rats, of which 30 were treated with tumor necrosis factor-alpha(TNF)-neutralizing compounds. During the course of arthritis, paw print analysis parameters and measures for mechanical and thermal hyperalgesia were obtained. Knee joints harvested on either day 3 or day 21 were scored histologically for signs of inflammation and cartilage and bone destructions. Data were compared to those obtained from 33 immunized control rats and correlated for days 3 and 21. Arthritic rats showed distinct asymmetric gait abnormalities. In the acute stage of antigen-induced arthritis, but not in the chronic phase, there was a significant correlation between the gait parameter 'left-right distance' and measures of primary and secondary hyperalgesia. Both in the acute and chronic phases, however, the gait parameter 'angle between paws' indicating outward rotation of paws mainly correlated with joint destruction as assessed using histology. Etanercept treatment exhibited pronounced anti-nociceptive and pro-locomotional effects, but the described correlations remained. In conclusion, some parameters of gait analysis may represent a good measure for arthritis pain, mainly in acute inflammation, while others are increasingly influenced by mechanical joint deformation as indicated by cartilage and bone destructions. Thus, gait abnormalities may not unequivocally be suitable for objective pain assessment in all stages of experimental arthritis.

Video-gait analysis of functional recovery of nerve repaired with chitosan nerve guides

Quantitative analysis of peripheral nerve regeneration using nerve guides is commonly evaluated through histomorphometry and walking track analysis. We conducted a unique assessment of functional sciatic nerve recovery treated with chitosan nerve guides. We used video-gait analysis to evaluate the extent of functional nerve recovery by measuring the ankle angle at different gait cycle phases. We also correlated the gastrocnemius muscle weight measurements and histological analysis to functional nerve recovery. The chitosan group showed increased functional improvement compared to the control groups at the end of a 12-week period ( p < 0.05). Although both control and chitosan angle measurements were lower than those recorded for presurgery animals, the angle measurements significantly improved over the 12-week period. Stance phase duration of the gait cycle was also recorded, which showed a significant increase over the 12-week time period. The muscle weight parameter indicated a significant decrease in muscle atrophy and restoration of functional strength. Histological analysis revealed that the chitosan nerve guide provided significantly increased axonal growth. The functional results indicated that chitosan nerve guides enhanced functional improvement over no repair processes.

A Sensitive Gait Parameter for Quantification of Arthritis in Rats

Quantification of arthritis is helpful for investigating pain mechanisms of arthritis and for developing new drugs. We assessed and identified a feasible parameter for quantification of rat arthritis using a novel gait analyzing system. Knee-joint injection with small doses of lambda-carrageenan decreased swing time ratio (STR, swing time of the non-treated hindlimb/swing time of the lambda-carrageenan-injected hindlimb) in a dose-dependent manner. Intraperitoneal treatment with indomethacin restored the decreased STR dose-dependently. The arthritis could not be accurately quantified by swing time and swelling, common indices of arthritis. These results show that STR is a sensitive, reliable parameter for quantification of arthritis.

ICAM-1 expression and leukocyte behavior in the microcirculation of chronically ischemic rat skeletal muscles

In muscle microcirculation, short periods of ischemia followed by reperfusion are known to upregulate leukocyte and endothelial adhesion molecules, but little is known about leukocyte adherence and ICAM-1 expression during chronic ischemia or any likely effect of muscle activity which is recommended in chronic ischemia due to peripheral arterial disease. Leukocyte rolling and stationary adhesion were observed in post-capillary venules in ischemic and contralateral rat extensor digitorum longus (EDL) muscles 3 and 7 days after unilateral ligation of the common iliac artery and in 3-day ischemic EDLs that were electrically stimulated on days 1 and 2 post-ligation (7 x 15 min per day). ICAM-1 was localized immunohistochemically to venular vessels in all muscles. Following ligation, use of the ischemic leg was observed to be restricted for the first 3 days, returning to normal by 7 days. After 3 days, leukocyte rolling/adherence and ICAM-1 expression were no different in ischemic than control muscles, but all were increased in contralateral muscles. In ischemic muscles, electrical stimulation doubled the numbers of rolling leukocytes and upregulated ICAM-1 expression. After 7 days, increased muscle activity as a result of natural movement also resulted in greater ICAM-1 expression, a 4- to 5-fold increase in rolling leukocyte numbers and a 3-fold increase in stationary adherent leukocytes. Chronic ischemia thus increases ICAM-1 and leukocyte adherence in muscle microcirculation only when combined with contractile activity. Post-capillary venular endothelium may be modified by muscle acidosis when contractions are performed under low flow conditions or by changes in rheological (shear force) factors.

Force plate for measuring the ground reaction forces in small animal locomotion

The importance of kinetic force plate studies of locomotion in small animals has grown recently with the increasing use of rodent models for studies of musculoskeletal diseases. However, the force plates for use with animals much smaller than a cat are difficult to design and use. Here we present data on a commercially available small force plate that accurately collects whole-body and, in a modified form, single-limb ground reaction forces in mice. The method used here is convenient, inexpensive, and readily adaptable for use with a variety of small species.

Functional assessment of peripheral nerve recovery in the rat: gait kinematics

Computerized rat gait analysis has become an invaluable technique of functional evaluation for some peripheral nerve investigators, comparing the normal and the pathological kinematic data. Appropriate selection of the methods to evaluate the functional outcome should be sensitive enough to moderate changes. By combining kinematic data and traditional methods in regeneration studies, it is possible to achieve better documentation of functional changes with the passage of time. A review of the three commonly kinematic parameters used in nerve regeneration studies, such as the calculation of sciatic function index, stance factor, and ankle angle, will provide the reader with detailed information about this accurate and consistent means of evaluating peripheral nerve function after nerve injury and repair. This study aims to review the different methods and potentialities of the rat gait kinematics as a noninvasive evaluation during regeneration, allowing for measurement of the rate of functional recovery in experimental studies.

Ground reaction force pattern in limbs with intermittent claudication

OBJECTIVES

to investigate the presence of a ground reaction force pattern specific to the patient with unilateral intermittent claudication (IC), and the relationship of this pattern with onset of claudication.

DESIGN

identification of impulse pattern during gait of lower limbs with and without ischaemia, in patients with unilateral IC and controls.

METHODS

thirty patients with unilateral IC and six peripheral arterial disease non-claudicant patients had their gait recorded using the F-Scan system during a treadmill test. Their plantar impulse pattern was calcuated. Examined lower limbs were subdivided into groups: ischaemic limbs (30), contralateral limbs (30) and lower limbs of patients without IC (12). Two impulse patterns were found: the descending one, where impulse values decrease during gait, and the non-descending one, where these values do not decrease during gait. The numerical distribution of patterns among limb groups was determined and their ratios compared. Correlation between claudication onset and impulse pattern was also investigated.

RESULTS

most ischaemic limbs exhibited a descending pattern, in contrast with control and contralateral non-ischaemic limbs (p<0.02). There was no relationship between impulse pattern and claudication onset.

CONCLUSIONS

ischaemic lower limbs present the descending pattern of plantar impulse. No relationship exists between this pattern and claudication pain.

Exercise training for claudicants: changes in blood flow, cardiorespiratory status, metabolic functions, blood rheology and lipid profile

OBJECTIVE

Exercise training improves the walking distance of claudicants. The aim of this study was to investigate factors associated with the improvement in the maximum walking distance (MWD) in respect to cardiovascular, respiratory and metabolic adaptations.

METHODS

Forty claudicants were studied. Common femoral artery blood flow (BF), heart rate (HR), oxygen consumption (VO(2)), respiratory exchange ratio (RER), lactate levels, blood rheology and lipid profiles were measured. Tests were repeated after 3 months of exercise training.

RESULTS

Fifteen patients did not complete the exercise program. For patients who did complete the program, MWD improved by 82%. A significant reduction in HR and VO(2)during exercise was demonstrated. No significant changes occurred in BF or RER. Although MWD increased significantly, there was no increase in recovery VO(2)(oxygen debt). A significant reduction in post-exercise lactate levels occurred. Blood rheology was unchanged, but an improvement in HDL levels was noted.

CONCLUSIONS

Many claudicants could not complete an exercise program, mainly due to osteoarthritis. Exercise training improved exercise tolerance significantly without any increase in BF. The HR and oxygen cost of similar exercise was reduced. An improved MWD did not correlate with a higher oxygen debt or lactate load. Favourable changes in lipid profiles occurred.

Exercise training and peripheral vascular disease

BACKGROUND

Conservative management is advocated as a treatment of choice for patients with intermittent claudication. This is a review of the mechanisms behind the improvement following an exercise rehabilitation programme.

METHODS

All Medline articles from the National Library of Medicine, USA containing the text words 'claudication' or 'peripheral vascular disease' and 'exercise' were reviewed. Cross-referencing from relevant articles was carried out.

RESULTS AND CONCLUSION

The poor physical status of a patient with intermittent claudication is not solely due to a reduction in blood flow to the lower limbs; associated factors, such as metabolic inefficiency, poor cardiorespiratory reserve and exercise-induced inflammation contribute. An exercise programme frequently improves both the physical aspect and quality of life, and the success of such exercise is multifactorial. An increase in the blood flow to the lower extremity is uncommon. Other factors, such as a redistribution of blood flow, changes in oxidative capacity of the skeletal muscles and greater utilization of oxygen, occur and the associated metabolic dysfunction of the skeletal muscles is rectified. Following exercise training, blood rheology improves and exercise-induced inflammation is ameliorated; cardiorespiratory status also benefits and the oxygen cost of exercise decreases.

Correlation of hemodynamic and functional variables with the angiographic extent of peripheral arterial occlusive disease

The aim of the study was to determine whether hemodynamic and functional variables are related to the angiographic extent of lower limb atherosclerosis. In 150 patients with stable intermittent claudication, the Bollinger angiogram score was compared with the resting Doppler pressure values, and the initial claudication distance (ICD) and absolute claudication distance (ACD) with treadmill exercise. The extent of lower limb atherosclerosis correlated significantly with the age of the patients and the duration of the claudication. The angiogram scores of the patients were negatively correlated with the ankle systolic blood pressure (SBP) and the ankle/brachial index (ABI). In a multiple regression analysis, ABI was the most predictive variable for the angiographic severity of disease. ICD, ACD and work on the treadmill failed to correlate with the angiogram summation score. If patients were classified into groups for those with iliac or femoropopliteal disease, a weak correlation between ACD and femoropopliteal angiogram score was found. The comparison between Doppler measurements and treadmill exercise testing showed no significant correlation between SBP/ABI of the more diseased limb and ICD. However, both SBP and ABI did correlate significantly with ACD (r = 0.16, p < 0.05 and r = 0.20, p < 0.01, respectively). In conclusion, SBP and ABI are reliable parameters for indirect assessment of the angiographic extent of lower limb atherosclerosis. In contrast, the walking capacity of claudicant patients is independent of the angiographic severity of the disease.

Oxygen uptake during constant-intensity exercise in patients with peripheral arterial occlusive disease

The purpose of the present study was to evaluate the oxygen uptake (VO2) response to walking in patients with peripheral arterial occlusive disease (PAOD) at a constant velocity and to determine whether the oxygen uptake observed during constant-intensity exercise in this population is associated with the severity of PAOD. Forty-nine PAOD patients with intermittent claudication were recruited (values are mean +/- SD) [age = 66.4 +/- 8.0 years, weight = 83.3 +/- 16.0 kg, body mass index = 28.8 +/- 5.6, ankle/brachial systolic blood pressure index (ABI) = 0.63 +/- 0.18, VO2peak = 13.02 +/- 2.99 ml/kg/min]. Patients were evaluated during a 2.0 miles/h walk on a treadmill until maximal claudication pain or for a maximum of 20 minutes. On average, patients walked for a duration of 10.3 +/- 5.8 min. Despite the constant absolute intensity during the exercise bout, there was a significant (p < 0.01) 4.0% increase in VO2 from min 3 of exercise (10.58 +/- 2.02 ml/kg/min) to min 5 (11.01 +/- 2.18 ml/kg/min) and a further 4.0% increase from min 5 to the end of exercise (11.46 +/- 2.32 ml/kg/min). Expressed as relative exercise intensity, this represented an increase from 80.8 +/- 18.3% to 87.1 +/- 18.0% of VO2peak from min 3 to the end of exercise. The magnitude of increase in VO2 during the exercise bout was not correlated with resting ABI (r = 0.00, p = 0.68) or post-exercise ABI (r = 0.04, p = 0.73). There was a nonsignificant trend towards a correlation between the time to onset of claudication pain and the magnitude of increase in VO2 (r = 0.25, p = 0.08). Results of this study suggest that an increase in VO2 occurs during constant-velocity walking at a high relative intensity in PAOD patients. This increase in VO2 does not appear to be related to the severity of PAOD.

Improved walking economy in patients with peripheral arterial occlusive disease

The effect of exercise rehabilitation on the oxygen cost of ambulation in patients with peripheral arterial occlusive disease (PAOD) was evaluated with specific emphasis on the effects of exercise rehabilitation on the slow component of VO2. Because the slow component of VO2 represents an increase in VO2 despite constant-intensity exercise, it can profoundly affect the relative energy cost of exercise in individuals with a low functional capacity. Twenty-six patients with intermittent claudication performed treadmill walking at 2.0 mph/0% grade for 20 min or until maximal claudication pain before and after 4 months of rehabilitation. The slow component of VO2 during the treadmill test was defined as the difference between the end-exercise VO2 and the VO2 observed at minute 3. Ankle/brachial systolic pressure index (ABI) was measured before and immediately following the exercise test. Rehabilitation consisted of 3 d x wk(-1) of treadmill walking for 15-30 min at 60-70% of VO2peak. The slow component of VO2 and end-exercise VO2 at pretraining (0.75 +/- 0.90 and 11.12 +/- 2.10 mL x kg[-1] x min[-1]) were significantly reduced after 4 months of exercise rehabilitation (-0.07 +/- 1.11 and 10.07 +/- 1.80 mL x kg[-1] x min[-1]; P < 0.05). Exercise rehabilitation also significantly (P < 0.05) increased the post-exercise ABI (pre-rehabilitation = 0.36 +/- 0.26, post-rehabilitation = 0.43 +/- 0.25). These data suggest that 4 months of exercise rehabilitation: 1) improves walking economy in PAOD patients because of a decreased slow component of VO2, and 2) increases post-exercise ABI.