Changes in Passive Mechanical Properties of the Gastrocnemius Muscle at the Muscle Fascicle and Joint Levels in Stroke Survivors

Gao F, Grant TH, Roth EJ, Zhang L-Q. Changes in passive mechanical properties of the gastrocnemius muscle at the muscle fascicle and joint levels in stroke survivors.

Objectives

To investigate the ankle joint-level and muscle fascicle-level changes and their correlations in stroke survivors with spasticity, contracture, and/or muscle weakness at the ankle.

Design

To investigate the fascicular changes of the medial gastrocnemius muscle using ultrasonography and the biomechanical changes at the ankle joint across 0°, 30°, 60°, and 90° knee flexion in a case-control manner.

Setting

Research laboratory in a rehabilitation hospital.

Participants

Stroke survivors (n=10) with ankle spasticity/contracture and healthy control subjects (n=10).

Interventions

Not applicable.

Main Outcome Measurements

At the muscle fascicle level, medial gastrocnemius muscle architecture including the fascicular length, pennation angle, and thickness were evaluated in vivo with the knee and ankle flexion changed systematically. At the joint level, the ankle range of motion (ROM) and stiffness were determined across the range of 0° to 90° knee flexion.

Results

At comparable joint positions, stroke survivors showed reduced muscle fascicle length, especially in ankle dorsiflexion (P≤.048) and smaller pennation angle, especially for more extended knee positions (P≤.049) than those of healthy control subjects. At comparable passive gastrocnemius force, stroke survivors showed higher fascicular stiffness (P≤.044) and shorter fascicle length (P≤.025) than controls. The fascicle-level changes of decreased muscle fascicle length and pennation angle and increased medial gastrocnemius fascicle stiffness in stroke were correlated with the joint level changes of increased joint stiffness and decreased ROM (P<.05).

Conclusions

This study evaluated specific muscle fascicular changes as mechanisms underlying spasticity, contracture, and joint-level impairments, which may help improve stroke rehabilitation and outcome evaluation.     

Gastrocnemius tightness on joint angle and work of lower extremity during gait

Background

Muscular tightness is a common clinical musculoskeletal disorder and is regarded as a predisposing factor for muscle injuries. In this study, a two-way mixed design ANOVA was applied to investigate the effects of the gastrocnemius tightness on the joint angle and joint work during walking.

Methods

Twenty-two patients with muscular tightness of gastrocnemius muscle (<12° of ankle dorsiflexion with knee extended) and 22 age- and gender-matched subjects with normal gastrocnemius flexibility (>15° of ankle dorsiflexion with knee extended) participated in this study. The joint angle and work at hip, knee, and ankle joints during the stance phase were analyzed at two preset cadences of 100 steps/min and 140 steps/min.

Findings

Significantly greater flexion angles at hip (P = 0.025) and knee (P = 0.001) were found in the tightness group at the time of maximal ankle dorsiflexion. Significantly less work generation at knee (P = 0.034) and greater work absorption at ankle (P = 0.024) were detected in the tightness group.

Interpretation

The subjects with gastrocnemius tightness revealed a compensatory gait pattern, which included the changes in the joint angles and associated work productions. The potential disturbance of the knee control and strain injuries of plantar flexors might be crucial in the clinical considerations for subjects with gastrocnemius tightness.     

The association between lower extremity energy absorption and biomechanical factors related to anterior cruciate ligament injury

Background

Greater total energy absorption by the lower extremity musculature during landing may reduce stresses placed on capsuloligamentous tissues with differences in joint contributions to energy absorption potentially affecting anterior cruciate ligament injury risk. However, the relationships between energy absorption and prospectively identified biomechanical factors associated with non-contact anterior cruciate ligament injury have yet to be demonstrated.

Methods

Sagittal plane total, hip, knee and ankle energy absorption, and peak vertical ground reaction force, anterior tibial shear force, knee flexion and knee valgus angles, and internal hip extension and knee varus moments were measured in 27 individuals (14 females, 13 males) performing double leg jump landings. Correlation coefficients assessed the relationships between energy absorption during three time intervals (initial impact phase, terminal phase, and total landing) and biomechanical factors related to anterior cruciate ligament injury.

Findings

More favorable values of biomechanical factors related to non-contact anterior cruciate ligament injury were associated with: 1) Lesser total (R² = 0.178–0.558), hip (R² = 0.229–0.651) and ankle (R² = 0.280), but greater knee (R² = 0.147) energy absorption during the initial impact phase; 2) Greater total (R² = 0.170–0.845), hip (R² = 0.599), knee (R² = 0.236–0.834), and ankle (R² = 0.276) energy absorption during the terminal phase of landing; and 3) Greater knee (R² = 0.158–0.709), but lesser hip (R² = 0.309) and ankle (R² = 0.210–0.319) energy absorption during the total landing period.

Interpretation

These results suggest that biomechanical factors related to anterior cruciate ligament injury are influenced by both the magnitude and timing of lower extremity energy absorption during landing.     

Dynamic joint stiffness and co-contraction in subjects after total knee arthroplasty

Background

Although total knee arthroplasty reduces pain and improves function, patients continue to walk with asymmetrical movement patterns, that may affect muscle activation and joint loading patterns. The purpose of this study was to evaluate the specific biomechanical abnormalities that persist after total knee arthroplasty and examine the neuromuscular mechanisms that may contribute to these asymmetries.

Methods

Dynamic joint stiffness at the hip, knee and ankle, as well as co-contraction at the knee and ankle, were compared between the operated and non-operated limbs of 32 subjects who underwent total knee arthroplasty and 21 subjects without lower extremity impairment.

Findings

Subjects after total knee arthroplasty demonstrated higher dynamic joint stiffness in the operated knee compared to the non-operated knee (0.056 (0.023) Nm/kg/m/deg vs. 0.043 (0.016) Nm/kg/m/deg, P = 0.003) and the knees from a control group without lower extremity pathology (controls: 0.042 (0.015) Nm/kg/m/deg, P = 0.017). No differences were found between limbs or groups for dynamic joint stiffness at the hip or ankle. There was no relationship between dynamic joint stiffness at the knee and ankle and the amount of co-contraction between antagonistic muscles at those joints.

Interpretation

Patients after total knee arthroplasty walk with less knee joint excursion and greater knee stiffness, although no differences were found between groups for stiffness at the hip or ankle. Mechanisms other than co-contraction are likely the underlying cause of the altered knee mechanics. These findings are clinically relevant because the goal should be to create interventions to reduce these abnormalities and increase function.     

Frontal plane compensatory strategies associated with self-selected walking speed in individuals post-stroke

Background

Approximately two out of three individuals post-stroke experience walking impairments. Frontal plane compensatory strategies (i.e. pelvic hiking and circumduction) are observed in post-stroke gait in part to achieve foot clearance in response to reduced knee flexion and ankle dorsiflexion. The objective of this study was to investigate the relationship between self-selected walking speed and the kinematic patterns related to paretic foot clearance during post-stroke walking.

Methods

Gait analysis was performed at self-selected walking speed for 21 individuals post-stroke. Four kinematic variables were calculated during the swing phase of the paretic limb: peak pelvic tilt (pelvic hiking), peak hip abduction (circumduction), peak knee flexion, and peak ankle dorsiflexion. Paretic joint angles were analyzed across self-selected walking speed as well as between functionally relevant ambulation categories (Household < 0.4 m/s, Limited Community 0.4–0.8 m/s, Community > 0.8 m/s).

Findings

While all subjects exhibited similar foot clearance, slower walkers exhibited greater peak pelvic hiking and less knee flexion, ankle dorsiflexion, and circumduction compared to faster walkers (P < .05). Additionally, four of the fastest walkers compensated for poor knee flexion and ankle dorsiflexion through large amounts of circumduction.

Interpretation

These findings suggest that improved gait performance after stroke, as measured by self-selected walking speed, is not necessarily always accomplished through gait patterns that more closely resemble healthy gait for all variables. It appears the ability to walk fast is achieved by either sufficient ankle dorsiflexion and knee flexion to achieve foot clearance or the employment of circumduction to overcome a deficit in either ankle dorsiflexion or knee flexion.     

Talar Positional Fault in Persons With Chronic Ankle Instability

Wikstrom EA, Hubbard TJ. Talar positional fault in persons with chronic ankle instability.

Objective

To determine whether sagittal plane talar position differs between uninjured controls and individuals with chronic ankle instability (CAI) using lateral ankle radiographs.

Design

Single-blind case control.

Setting

University-based sports medicine research laboratory.

Participants

University students (N=48) volunteered to participate. Twenty-four uninjured controls (12 men, 12 women; mean ± SD, 21.8±2.6y; 170±10cm; 73±16kg), and 24 adults with CAI (12 men, 12 women; 21.7±2.8y; 175±13cm; 71±13kg) participated.

Intervention

A single nonweight-bearing lateral radiograph was taken of each ankle. Subjects were positioned side lying with the hip and knee in a neutral position in the transverse plane and the ankle joint in a neutral position (90° of dorsiflexion, 0° of inversion/eversion).

Main Outcome Measure

The sagittal plane talar position was calculated as the distance between the most anterior margin of the inferior tibia and the most anterior margin of the talar dome in millimeters for each radiograph.

Results

Talar position was significantly more anterior in the involved CAI limb (3.69±1.37mm) than the uninvolved CAI limb (2.98±1.61mm; P=.03). Additionally, an anterior talar position was significantly greater in the involved CAI limb than the matched control limb (2.65±1.24cm; P<.01). No differences were found between the uninvolved CAI limb and the matched control group limb (P=.57) or between the limbs of the uninjured control group (P=.75). Intratester reliability was found to be .90, while intertester reliability was .78.

Conclusions

An anterior talar positional fault is present in the involved limb of individuals with CAI relative to their uninvolved limb and compared with the matched limb of a control group. The talar position measurement technique has excellent intratester and intertester reliability.     

The effect of anti-pronation foot orthoses on hip and knee kinematics and muscle activity during a functional step-up task in healthy individuals: A laboratory study

Background

Greater frontal and transverse plane hip and knee motion, and delayed gluteus medius and vastus medialis oblique activation have frequently been identified in patellofemoral pain syndrome populations, whilst prefabricated anti-pronation foot orthoses have been reported to reduce symptoms. The aim of the study was to evaluate the effects of such orthoses on hip and knee kinematics, gluteal and vasti muscle activity, kinematic and electromyographic interactions alongside correlations with specific clinical measures.

Methods

Eighteen asymptomatic individuals (11 male 7 female) had measures taken of static foot posture and ankle range of motion. Hip muscle activity and kinematics were measured using electromyography and an active motion capture system during a step-up task. Order of testing with or without orthoses was determined using a coin toss.

Findings

Between condition paired t-tests indicated significantly reduced peak hip adduction angles (1.56°, P < 0.05) and significantly reduced knee internal rotation (1.3°, P < 0.05) in the orthoses condition. Reduced ankle dorsiflexion range of motion correlated with a reduction in hip adduction following the orthoses intervention (r = 0.59, P = 0.013).

Interpretation

The effects of prefabricated orthoses may be partially explained by kinematic alterations that occur proximal to the foot in the kinetic chain. These clinically and biomechanically relevant effects appear more evident in those with reduced underlying ankle motion. Further research is indicated using a symptomatic population to explore the clinical relevance of these observations.     

Lateral wedge insoles for medial knee osteoarthritis: effects on lower limb frontal plane biomechanics

Background

Lateral wedges reduce the peak knee adduction moment and are advocated for knee osteoarthritis. However some patients demonstrate adverse biomechanical effects with treatment. Clinical management is hampered by lack of knowledge about their mechanism of effect. We evaluated effects of lateral wedges on frontal plane biomechanics, in order to elucidate mechanisms of effect.

Methods

Seventy three participants with knee osteoarthritis underwent gait analysis with and without 5° lateral wedges. Frontal plane parameters at the foot, knee and hip were evaluated, including peak knee adduction moment, knee adduction angular impulse, center of pressure displacement, ground reaction force, and knee-ground reaction force lever arm.

Findings

Lateral wedges reduced peak knee adduction moment and knee adduction angular impulse (− 5.8% and − 6.3% respectively, both P < 0.001). Although reductions in peak moment were correlated with more lateral center of pressure (r = 0.25, P < 0.05), less varus malalignment (r values 0.25-0.38, P < 0.05), reduced knee-ground reaction force lever arm (r = 0.69, P < 0.01), less hip adduction (r = 0.24, P < 0.05) and a more vertical frontal plane ground reaction force vector (r = 0.67, P < 0.001), only reduction in knee-ground reaction force lever arm was significantly predictive in regression analyses (B = 0.056, adjusted R² = 0.461, P < 0.001).

Interpretation

Lateral wedges significantly reduce peak knee adduction moment and knee adduction angular impulse. It seems a reduced knee-ground reaction force lever arm with lateral wedges is the central mechanism explaining their load-reducing effects. In order to understand why some patients do not respond to treatment, future evaluation of patient characteristics that mediate wedge effects on this lever arm is required.     

Association of Dynamic Joint Power With Functional Limitations in Older Adults With Symptomatic Knee Osteoarthritis

Segal NA, Yack HJ, Brubaker M, Torner JC, Wallace R. Association of dynamic joint power with functional limitations in older adults with symptomatic knee osteoarthritis.

Objectives

To determine which lower-limb joint moments and powers characterize the level of gait performance of older adults with symptomatic knee osteoarthritis (OA).

Design

Cross-sectional observational study.

Setting

University motion analysis laboratory.

Participants

Community-dwelling adults (N=60; 27 men, 33 women; age 50-79y) with symptomatic knee OA.

Interventions

Not applicable.

Main Outcome Measures

Physical function was measured using the long-distance corridor walk, the Short Physical Performance Battery, and the Late Life Function and Disability Instrument (LLFDI Function). Joint moments and power were estimated using an inverse dynamics solution after 3-dimensional computerized motion analysis.

Results

Subjects aged 64.2±7.4 years were recruited. Ranges (mean ± SD) for the 400-m walk time and the LLFDI Advanced Lower-Limb Function score were 215.3 to 536.8 (304.1±62.3) seconds and 31.5 to 100 (57.0±14.9) points, respectively. In women, hip abductor moment (loading response), hip abductor power (midstance), eccentric hamstring moment (terminal stance), and power (terminal swing) accounted for 41%, 31%, 14%, and 48% of the variance in the 400-m walk time, respectively (model R²=.61, P<.003). In men, plantar flexor and hip flexor power (preswing) accounted for 19% and 24% of the variance in the 400-m walk time, respectively (model R²=.32, P=.025).

Conclusions

There is evidence that men and women with higher mobility function tend to rely more on an ankle strategy rather than a hip strategy for gait. In higher functioning men, higher knee extensor and flexor strength may contribute to an ankle strategy, whereas hip abductor weakness may bias women with lower mobility function to minimize loading across the knee via use of a hip strategy. These parameters may serve as foci for rehabilitation interventions aimed at reducing mobility limitations.     

Effects of walking with loads above the ankle on gait parameters of persons with hemiparesis after stroke

Background

Walking with a load at the ankle during gait training is a simple way to resist lower limb movements to induce functional muscle strengthening. This study investigated the effects of walking with different loads attached above the paretic ankle on biomechanical gait parameters during over ground walking in post-stroke participants.

Methods

Ten participants with moderate chronic hemiparesis were evaluated while walking over ground with three different loads (0.5, 1.0, and 1.5 kg) attached above the paretic ankle. Gait speed, cadence, step lengths as well as hip and knee angular displacements, joint moments and power of the paretic limb were compared while walking with and without loads.

Findings

Walking with a load led to an increased in gait speed (+ 0.03–0.05 m/s), and in step length of the paretic leg (+ 5.6 to 9.4% step length, effect size = 0.49–0.63), but not of the non-paretic leg. The proportion of the stance and swing phases did not change. Maximal joint moments (+ 20 to 48%, effect size = 0.26–0.55) and power (+ 20 to 114%, effect size = 0.30–0.57) increases varied across participants but were mostly affected in early stance at the hip and during the late swing phase at the knee. Mean angular displacement changes were less than 4°.

Interpretation

Post-stroke participants are able to increase hip and knee power bursts to meet the increased mechanical demand of added loads attached to the paretic ankle, while preserving the basic pattern of walking. Further study is needed before using loading to functionally strengthen paretic muscles.     

Association between energy cost of walking,muscle activation,and biomechanical parameters in older female fallers and non-fallers

Objective

To determine the nervous activation, muscle strength, and biomechanical parameters that influence the cost of walking in older fallers and non-fallers.

Methods

Maximal voluntary isokinetic torque was measured for the hip, knee and ankle of older women. Oxygen consumption was measured at rest and during 8 min of walking at self-selected speed. An additional minute of walking was performed to collect kinematic variables and the electromyographic signal of trunk, hip, knee, and ankle muscles, which was analyzed by the linear envelope. Cost of walking was calculated by subtracting resting body mass-normalized oxygen consumption from walking body mass-normalized oxygen consumption. Stride time and length, and ankle and hip range of motion were calculated from kinematic data.

Findings

Older adult fallers had 28% lower knee extensor strength (p = 0.02), 47% lower internal oblique activation at heel contact (p = 0.03), and higher coactivation between tibialis anterior and gastrocnemius lateralis in each of the gait phases (p < 0.05). For fallers, a higher activation of gluteus maximus was associated with a higher cost of walking (r = 0.55, p < 0.05 and r = 0.71, p < 0.01, before and after heel contact, respectively). For non-fallers, an association between cost of walking and age (r = 0.60, p = 0.01) and cost of walking and thigh muscle coactivation (r = 0.53, p = 0.01) existed.

Interpretation

This study demonstrated that there may be links between lower-extremity muscle weakness, muscle activation patterns, altered gait, and increased cost of walking in older fallers.     

Effects of fatiguing treadmill running on sensorimotor control in athletes with and without functional ankle instability

Background

Sensorimotor control is permanently impaired following functional ankle instability and temporarily decreased following fatigue. Little is known on potential interactions between both conditions. The purpose was to investigate the effect of fatiguing exercise on sensorimotor control in athletes with and without (coper, controls) functional ankle instability.

Methods

19 individuals with functional ankle instability, 19 ankle sprain copers, and 19 non-injured controls participated in this cohort study. Maximum reach distance in the star excursion balance test, unilateral jump landing stabilization time, center of pressure sway velocity in single-leg-stance, and passive ankle joint position sense were assessed before and immediately after fatiguing treadmill running. A three factorial linear mixed model was specified for each outcome to evaluate the effects of group, exhausting exercise (fatigue) and their interactions (group by fatigue). Effect sizes were calculated as Cohen's d.

Findings

Maximum reach distance in the star excursion balance test, jump stabilization time and sway velocity, but not joint position sense, were negatively affected by fatigue in all groups. Effect sizes were moderate, ranging from 0.27 to 0.68. No significant group by fatigue interactions were found except for one measure. Copers showed significantly larger prefatigue to postfatigue reductions in anterior reach direction (P ≤ 0.001; d = − 0.55) compared to the ankle instability (P = 0.007) and control group (P = 0.052).

Interpretation

Fatiguing exercise negatively affected postural control but not proprioception. Ankle status did not appear to have an effect on fatigue-induced sensorimotor control impairments.     

Stepping with an ankle foot orthosis re-examined: A mechanical perspective for clinical decision making

Background

Ankle foot orthoses are used to stabilize the ankle joint and aid toe clearance during stepping in persons after incomplete spinal cord injury. However, little is known about kinematics and kinetics of stepping with an orthosis during the transition from stance-to-swing and swing-to-stance. We intended to examine if an ankle foot orthosis impeded or facilitated optimal ankle, knee and hip joint kinematics, kinetics and spatiotemporal parameters during the transition phases of normal walking.

Methods

Fourteen healthy participants walked on a split-belt instrumented treadmill with and without a posterior leaf spring ankle foot orthosis at 1.2 m/s. Three dimensional motion data and ground reaction forces were captured during 30 second trials of steady state walking.

Findings

During stance-to-swing, the orthosis significantly decreased hip extension [8.6 (5.5) to 6.7 (5.5) degrees, P = 0.001], ankle plantarflexion [19.4 (5.7) to 12.0 (5.2) degrees, P < 0.001] and plantarflexor power [0.18 (0.03) to 0.15 (0.03) watts/body weight, P < 0.001]. During swing-to-stance, the orthosis significantly increased hip flexion [32.7 (4.7) to 35.6 (5.1) degrees, P = 0.028] and ankle plantarflexion [8.4 (3.5) to 10.9 (4.7) degrees, P < 0.001] and decreased loading rate [0.06 (0.01) to 0.05 (0.01) N/kg, P = 0.018] and braking force [0.16 (0.02) to 0.15 (0.02) N/kg, P = 0.013]. Double limb support time increased significantly with the orthosis [0.19 (0.02) to 0.22 (0.03) seconds, P < 0.000].

Interpretation

An ankle foot orthosis affected joint kinematics and kinetics during the transition from stance-to-swing and vice-versa. The use of orthosis to improve transition phase kinematics and kinetics in individuals with incomplete spinal cord injury warrants assessment.     

Correlation of plasma and synovial fluid osteopontin with disease severity in knee osteoarthritis

Objectives

The purposes of this study were to examine osteopontin levels in both plasma and synovial fluid of patients with primary knee osteoarthritis (OA) and to investigate their relationship with severity of the disease.

Design and methods

Thirty-two patients aged 53-83 years with knee OA and 15 healthy controls were enrolled in this study. Anteroposterior knee radiographs were taken to determine the disease severity of the affected knee. The radiographic grading of OA in the knee was performed by using the Kellgren-Lawrence criteria. Osteopontin levels in the plasma and synovial fluid were measured using enzyme-linked immunosorbent assay.

Results

The mean plasma osteopontin concentration of the knee OA patients was significantly higher compared with that of healthy controls (168.8 ± 15.6 vs 67.2 ± 7.7 ng/mL, P < 0.0001). Osteopontin levels in synovial fluid were significantly higher with respect to paired plasma samples (272.1 ± 15.0 vs 168.8 ± 15.6 ng/mL, P < 0.001). In addition, plasma osteopontin levels showed a positive correlation with synovial fluid osteopontin levels (r = 0.373, P = 0.035). Subsequent analysis showed that plasma osteopontin levels significantly correlated with severity of disease (r = 0.592, P < 0.001). Furthermore, the synovial fluid levels of osteopontin also correlated with disease severity (r = 0.451, P = 0.01).

Conclusion

The data suggest that osteopontin in plasma and synovial fluid is related to progressive joint damage in knee OA. Osteopontin may serve as a biochemical marker for determining disease severity and could be predictive of prognosis with respect to the progression of knee OA.     

Resistance training is accompanied by increases in hip strength and changes in lower extremity biomechanics during running

Background

Movement and muscle activity of the hip have been shown to affect movement of the lower extremity, and been related to injury. The purpose of this study was to determine if increased hip strength affects lower extremity mechanics during running.

Methods

Within subject, repeated measures design. Fifteen healthy women volunteered. Hip abduction and external rotation strength were measured using a hand-held dynamometer. Three-dimensional biomechanical data of the lower extremity were collected during running using a high-speed motion capture system. Measurements were made before, at the mid-point, and after a 6-week strengthening program using closed-chain hip rotation exercises. Joint range of motion (rearfoot eversion, knee abduction, hip adduction, and internal rotation), eversion velocity, eversion angle at heel strike, and peak joint moments (rearfoot inversion, knee abduction, hip abduction, and external rotation) were analyzed using repeated measures analysis of variance (P ? 0.05). The independent variable was time (pre-, week 3, and week 6). A separate analysis of variance was conducted with the dependent variables of peak hip abduction and external rotation strength.

Findings

Hip abduction (P = 0.009) and external rotation strength (P < 0.0005) increased by 13% and 23%, respectively. Eversion range of motion decreased (P = 0.05), hip adduction range of motion increased (P = 0.05), and a trend of decreased hip internal rotation range of motion (P = 0.08) were found. Rearfoot inversion moment (P = 0.02) and knee abduction moment (P = 0.05) decreased by 57% and 10%, respectively.

Interpretation

The hip abductors and external rotators were strengthened, leading to an alteration of lower extremity joint loading which may reduce injury risk. These exercises could be used in the rehabilitation, or prevention, of lower extremity injuries.     

Changes in Ankle Mechanical Stability in Those With Knee Osteoarthritis

Hubbard TJ, Hicks-Little C, Cordova M. Changes in ankle mechanical stability in those with knee osteoarthritis.

Objective

To examine ankle joint mechanical stability in patients who had mild to moderate knee osteoarthritis (OA).

Design

Case control study.

Setting

Biodynamics research laboratory.

Participants

Subjects with knee OA (n=15; 5 men and 10 women; mean age ± SD, 60.3±10.2y; mean mass ± SD, 93.9±18.3kg; mean height ± SD, 167.23±9.5cm) were matched to healthy controls (n=15; 5 men and 10 women; mean age ± SD, 59.6±12.6y; mean mass ± SD, 83.5±19.2kg; mean height ± SD, 169.7±12.6cm).

Interventions

Not applicable.

Main Outcome Measures

Mechanical ankle-subtalar joint stability was assessed with an instrumented arthrometer where ankle-subtalar joint motion for anterior/posterior displacement and inversion/eversion rotation was measured. Separate 2 × 2 mixed model analyses of variance were performed.

Results

Significant group × side interactions were observed for anterior and posterior displacement (P<.05) where patients with knee OA had significantly less anterior and posterior ankle displacement compared with the control group, as well as compared with their unaffected extremity. Additionally, patients with knee OA had significantly (P<.05) less inversion/eversion rotation than their respective controls.

Conclusions

These data suggest that altered ankle joint mechanics may be the result of deviations in ankle joint alignment secondary to the structural changes at the knee. Compensatory changes in ankle joint mechanics must also be considered when addressing lower extremity functional deficits in patients with knee OA.     

The effect of neutral-cushioned running shoes on the intra-articular force in the haemophilic ankle

Background

The ankle continues to be one of the most affected joints in the haemophilia patient, and as cartilage damage progresses, the joint can feel unstable, painful and stiff. Anecdotally, patients often report that sports trainers can improve their pain and daily function, however the actual mechanism for this remains unclear.

Methods

Nine patients with ankle haemarthropathy and three controls were examined using ‘CODAmotion’ analysis and a force plate. Kinematic and kinetic variables of the hip, knee and ankle were recorded. Data was imported from CODA to Excel, where a programme using 2D modelling of the ankle joint forces was employed. This calculated intra-articular force from heel strike to toe-off.

Findings

The haemophilia group at midstance showed an increase in intra-articular force in the ankle when wearing the trainer compared to the shoe (P = < 0.05). Overall the haemophilia cohort had an increased joint force in both the trainers and shoes, compared to controls.

Interpretation

The type of footwear worn by individuals with ankle arthropathy has a significant effect on the amount of force acting at the joint surface. Sports shoes, in providing better comfort and foot support, may facilitate an increased muscular activity around the ankle and therefore improved dynamic joint stability, accounting for why some patients with ankle arthropathy report less pain. Further research is needed to establish levels of acceptable force and the combined effects of orthotics and footwear.     

Transmission of whole body vibration in children while standing

Background

Whole body vibration has recently been used as a therapeutic intervention for the treatment of children with disabling conditions. Researchers of these studies observed encouraging results; however, children may not be capable of attenuating high vibration accelerations to the head because of low mass. The purpose of this study was to determine if children transmit vibration differently than adults while standing on a vibration platform.

Methods

The experimental protocol required 11 children and 10 adults to stand on a commercially available vibration platform at progressively greater frequencies (28, 33, and 42 Hz). Transmissibility of vibration to various skeletal landmarks was assessed with a high speed motion analysis system.

Findings

Transmissibility in children was 42% and 62% greater than adults for the ankle and hip, respectively (P = 0.03; effect size = 0.84–1.29). The values at the head were not different between groups (P = 0.92) and remained 86% and 50% lower than values at the ankle and knee, respectively (effect size = 4.75–19.1).

Interpretation

Transmissibility of whole body vibration while standing is not markedly different between children and adults. In fact, the only differences are the transmissibility to the ankle and hip which are greater in children when the vibration platform is set at 33 Hz. More importantly, transmissibility to the head is not different between groups. These results do not suggest vibration therapy is safe as the biological response of children to acute or chronic acceleration impacts during whole body vibration is unknown.     

Bed exercises following total hip replacement: a randomised controlled trial

Objectives

To determine whether the addition of bed exercises after primary total hip replacement (THR) improves functional outcomes and quality of life, in adult patients, during the first six postoperative weeks.

Design

Single-blind randomised controlled trial.

Setting

Inpatient and outpatient orthopaedic departments at a National Health Service hospital.

Participants

Sixty primary elective THR patients.

Intervention

Patients were assigned at random to receive either a standard gait re-education programme and bed exercises, or the standard gait re-education programme without bed exercises after THR. The bed exercises consisted of active ankle dorsiflexion/plantarflexion, active knee flexion, and static quadriceps and gluteal exercises.

Main outcome measures

Iowa Level of Assistance Scale (ILOA), the Short Form-12 Health Survey (SF-12), duration of hospital admission and postoperative complications were assessed at baseline, and 3 days and 6 weeks postoperatively.

Results

There was no statistically significant difference in ILOA scores between the two groups on the third postoperative day [gait re-education and bed exercise group median 40.5, interquartile range (IQR) 17.5 to 44.5; gait re-education alone group median 38, IQR 22.0 to 44.5; P = 0.70]. Although there was a small difference between the median ILOA scores at Week 6 between the two groups (3.5, IQR 0 to 6.4 and 5.0, IQR 3.5 to 12.5; P = 0.05), this difference was not statistically or clinically significant. There was no difference between the groups in duration of hospital admission, SF-12 scores or postoperative complications at Week 6.

Conclusion

This study suggests that during the first six postoperative weeks, the addition of bed exercises to a standard gait re-education programme following THR does not significantly improve patient function or quality of life.