Biomechanical and energetic effects of a stance-control orthotic knee joint

Users of traditional knee-ankle-foot orthoses (KAFOs) walk with either locked or unlocked knee joints depending on the level of stability required. Some users may benefit from new stance-control KAFOs that prevent stance-phase knee flexion but allow swing-phase flexion. We collected data from nine nondisabled adults who walked with KAFOs that incorporated the Horton Stance-Control Orthotic Knee Joint (SCOKJ) in the locked, unlocked, and auto (which provides knee stability during stance phase and knee flexion during swing phase) modes to investigate the biomechanical and energetic effects of stance-control orthoses. Studying nondisabled subjects allowed us to analyze the effects of stance-control orthoses in a homogenous population. In general, gait kinematics for the auto and unlocked modes were more similar than for the auto and locked modes. Despite the elimination of hip hiking in the auto mode, oxygen cost was not different between the auto and locked modes (p > 0.99). The SCOKJ allowed our nondisabled subjects to walk with a more normal gait pattern; however, future research should explore the effect of stance-control orthoses on persons with gait pathology.     

Preliminary kinematic evaluation of a new stance-control knee-ankle-foot orthosis

BACKGROUND: Stance-control knee-ankle-foot orthoses permit free knee motion in swing while providing knee flexion resistance in stance for individuals with quadriceps muscle weakness. However, some stance-control knee-ankle-foot orthoses require full knee extension to engage the knee-joint lock, thereby not providing knee support when climbing stairs or stepping over curbs. Stance-control knee-ankle-foot orthoses that do support a flexed knee are either heavy, bulky, expensive, offer a limited number of locking positions, or cause noise. This paper presents a preliminary kinematic evaluation of a new stance-control knee-ankle-foot orthosis that was designed to address these limitations. METHODS: Kinematic gait analysis was performed on three male knee-ankle-foot-orthosis users with knee extensor weakness in at least one limb (mean age: 56.3 years (SD 4.0)). Three walking trials were performed with the subjects' current knee-ankle-foot-orthosis and then the new stance-control knee-ankle-foot orthosis (non-randomized before-after trial). Subjects completed a questionnaire about the new stance-control knee-ankle-foot orthosis and current knee-ankle-foot-orthosis. FINDINGS: A mean increase in knee flexion of 21.1 degrees (SD 8.2) during swing and a greater total knee range of motion was found when walking with the new stance-control knee-ankle-foot orthosis. Two knee-ankle-foot-orthosis users experienced a reduction in pelvic obliquity and hip abduction angle abnormalities when walking with the stance-control knee-ankle-foot orthosis. Two out of three subjects preferred walking with the new stance-control knee-ankle-foot orthosis over their prescribed knee-ankle-foot-orthosis. INTERPRETATION: The new stance-control knee-ankle-foot orthosis permitted improved gait kinematics for knee-ankle-foot-orthosis users while providing knee support in stance and free knee motion in swing at appropriate instants in the gait cycle. Overall, the new stance-control knee-ankle-foot orthosis provided more natural gait kinematics for orthosis users compared to conventional knee-ankle-foot-orthoses.     

Pelvic and lower limb compensatory actions of subjects in an early stage of hip osteoarthritis

OBJECTIVE: To determine if compensatory actions take place at the pelvis and other joints of the affected lower limb in subjects who were in an early stage of hip osteoarthritis (OA). DESIGN: Nonrandomized, case-control study. SETTING: A gait laboratory. PARTICIPANTS: Seventeen patients with OA of the hip (clinical group) matched with 17 healthy elderly subjects (nonclinical group). INTERVENTIONS: Video data obtained while subjects walked a 10-meter walkway twice and stepped across a forceplate. MAIN OUTCOME MEASURES: Four phasic and temporal gait parameters (walking speed, stance phase relative duration, stride length, cadence) 10 pelvic (pelvic tilt, obliquity, rotation at push-off maximum range of motion for all 3) and hip (3 hip angles at push-off, maximum hip flexion) kinematic parameters, 3 hip moments, and twenty-seven 3-dimensional peak muscle powers (labeled by joint, peak power, plane) developed in the lower limb joints during the gait cycle. RESULTS: Subjects in the clinical group were characterized by a 12.4% slower walking speed. The pelvis was more upwardly tilted (2.5 times) at push-off in the clinical group than in the nonclinical group. Obliquity, measured in the frontal plane, revealed that the pelvis dropped more (2.4 times) on the unsupported limb of the clinical group at push-off. In the sagittal plane, subjects in the clinical group absorbed less energy in their second hip peak power for decelerating the thigh extension and generated less hip pull (third hip peak power) than the nonclinical group by 34% and 29%, respectively. In the sagittal plane, the clinical group had 57% lower second knee peak power to straighten the joint shortly after heel strike, and 43% less knee absorption (third peak power) at push-off. During the push-off phase, the clinical group developed more than twice their third peak knee power in the frontal plane and 5 times more their third peak knee power in the transversal plane than the peak knee power of the nonclinical group in an attempt to control knee adduction and to facilitate body-weight transfer by an internal rotation. At the end of the swing phase, the fourth peak power in the sagittal plane showed the absorption power required to decelerate the leg; it was reduced by 35% in the clinical group, representing a strategy to increase walking speed by lengthening the stride length. CONCLUSIONS: Even at an early stage of hip OA, joint degeneration was compensated by an increase in pelvis motion and muscle power generation or absorption modifications in other lower limb joints.     

Examining outcomes from total knee arthroplasty and the relationship between quadriceps strength and knee function over time

BACKGROUND: Temporal-spatial gait parameters improve following total knee arthroplasty (TKA) but lower limb kinematics and moments fail to match those of age-matched healthy individuals. The aim of this study was to determine whether quadriceps strength, clinical measures of knee function, lower limb kinematics, and joint moments improve following arthroplasty and normalize over time. METHODS: Twelve patients underwent total knee arthroplasty were tested at 3 and 12 months following surgery. Twelve matched controls were also tested. All underwent quadriceps strength testing and gait analysis to calculate knee joint kinematics and kinetics. Function was assessed using clinical tests and self-report. FINDINGS: All clinical measures except for quadriceps strength significantly improved from 3 to 12 months. Gait asymmetry was observed at 3 months (lower stance times, peak knee flexion angle, range of motion and vertical ground reaction force), but ankle, knee and hip moments contributing to the total limb support moment were equivalent between legs. At 12 months, gait speed remained significantly slower than controls. Inter-limb differences in peak knee flexion angle and range of motion persisted. Greater hip and lower knee moments were evident in the operated limb, compared to the non-operated limb and controls. Quadriceps strength was positively correlated with faster times on the Time Up and Go and Stair Climbing Test and greater distances during the 6 Minute Walk test. INTERPRETATION: Patients who have undergone TKA demonstrate improvements in function as measured by self-report and functional performance measures. Gait becomes more symmetric and quadriceps strength becomes stronger. Some approached the values of healthy control subjects. Important differences still remain however. The larger hip extensor contribution to the total support moment may be to compensate for the diminished knee extensor contribution during level walking. Since instrumented gait analysis and functional performance measures appear to reflect different aspects of recovery following total knee replacement, both should be considered when evaluating gait and function.     

The effect of footwear adapted with a multi-curved rocker sole in conjunction with knee-ankle-foot orthoses on walking in poliomyelitis subjects: a pilot study

Background: Knee-ankle-foot orthoses (KAFOs) are used by people with poliomyelitis to ambulate. Whist advances in orthotic knee joint designs for use in KAFOs such the provision of stance control capability have proven efficacy, little attention has been paid to shoe adaptations which may also improve gait.

Aim: The aim of this study was to evaluate the alteration to the kinematics and temporal-spatial parameters of gait caused by the use of heel-to-toe rocker-soled footwear when ambulating with KAFOs.

Method: Nine adults with a history of poliomyelitis who routinely wore KAFOs participated in the study. A heel-to-toe rocker sole was added to footwear and worn on the affected side. A three-dimensional motion capture system was used to quantify the resulting alteration to specific gait parameters.

Results: Maximum hip joint extension was significantly increased (p?=?0.011), and hip abduction and adduction were both significantly reduced (p?=?0.011 and p?=?0.007, respectively) when walking with the rocker sole. A significant increase in stride length (p?=?0.035) was demonstrated but there were no significant increases in either walking speed or cadence.

Conclusions: A heel-to-toe rocker sole adaptation may be useful for walking in patients with poliomyelitis who use KAFOs.

• Implications for Rehabilitation

• The poor functionality and difficulty in walking when using an orthotic device such as a KAFO which keeps the knee locked during ambulation, plus the significant energy required to walk, are complications of orthoses using.

• Little evidence exists regarding the biomechanical effect of walking with a KAFO incorporating fixed knee joints, in conjunction with rocker-soled footwear.

• The main aim of walking with a heel-to-toe rocker sole is to facilitate forward progression of the tibia when used with an AFO or KAFO or to provide easier walking for patients who have undergone an ankle arthrodesis.

• In this study, a rocker sole profile adaptation produced no significant alteration to hip joint flexion, but hip joint maximum extension was significantly increased in subjects suffering from poliomyelitis, and maximum hip adduction and abduction were both significantly reduced.

• The most significant alterations were seen in stride length, and although there was a significant increase in this parameter, there was no statistically significant increase in walking velocity or cadence.

     

Spastic paretic stiff-legged gait: biomechanics of the unaffected limb.

A concern for individuals with hemiparesis affecting their gait, which heretofore has never been studied, is the possibility that various compensations occurring in the unaffected limb may strain or fatigue the muscles or ligaments and/or predispose to joint injury in that limb. We studied the biomechanics of the unaffected limb during walking in 20 subjects with hemiparesis who had stiff-legged gait as a result of stroke. An optoelectronic motion analysis and force platform system was used to estimate torques in all three planes about the hip, knee, and ankle. Sagittal plane joint motion and power about the unaffected hip, knee, and ankle were also studied. Data were compared with control walking data collected from 20 able-bodied controls. On average, peak torques and powers were all either reduced or the same compared with controls, even though in some instances values were >2 standard deviations (SD) above the control means. Our findings suggest that on average the probability of excessive muscular-tendon effort and the risk for biomechanical injury in the unaffected limb are minimal compared with able-bodied, walking controls. However, given individual variability, we recommend routine clinical gait analysis for all people with stiff-legged gait to eliminate excessive values in certain biomechanical parameters, which could, if not addressed, predispose to muscle-tendon strain or joint or ligamentous injury.     

Increased power generation in impaired lower extremities correlated with changes in walking speeds in sub-acute stroke patients

Background

Establishing changes in net joint power in the lower extremity of patients during recovery of walking might direct gait training in early stroke rehabilitation. It is hypothesized that (1) net joint power in the lower extremity joints would increase in sub-acute stroke patients following gait rehabilitation, and (2) the improvements in net joint power would be significantly correlated with changes in walking speed.

Methods

Thirteen sub-acute patients (<3 months from stroke onset) participated in the study. All patients completed 6 weeks of gait training (3 weeks of robotic gait training and 3 weeks of physiotherapy). The gait patterns were analyzed using 3D motion analysis before and after training. The assessed variables were; gait speed and the net peak joint power of the ankle plantar flexors, hip extensors, hip flexors, hip abductors, and knee extensors.

Findings

Ankle plantar flexor power in the impaired limb and hip extensor power in the unimpaired limb increased significantly following training (133% and 77%, respectively; P < 0.002). Improvements (from 20% to 133%) in net joint power of the ankle plantar flexors, hip extensors, hip flexors, and hip abductors of the impaired limb and ankle plantar flexors and hip abductors of the unimpaired limb significantly correlated with the recovery of walking speed following training (0.24 m/s to 0.51 m/s) (r = 0.71–0.86).

Interpretation

The findings suggested investigations for strengthening the plantar flexors, hip flexors, hip extensors, and hip abductors concentrically, and knee extensors eccentrically in the impaired limb to determine the effectiveness in improving gait performance.     

Effect of carbon-composite knee-ankle-foot orthoses on walking efficiency and gait in former polio patients.

OBJECTIVE: To investigate the effects of total-contact fitted carbon-composite knee-ankle-foot orthoses (KAFOs) on energy cost of walking in patients with former polio who normally wear a conventional leather/metal KAFO or plastic/metal KAFO. DESIGN: A prospective uncontrolled study with a multiple baseline and follow-up design. Follow-up measurements continued until 26 weeks after intervention. PARTICIPANTS: Twenty adults with polio residuals (mean age 55 years). INTERVENTION: Each participant received a new carbon-composite KAFO, fitted according to a total-contact principle, which resulted in a rigid, lightweight and well-fitting KAFO. OUTCOME MEASURES: Energy cost of walking, walking speed, biomechanics of gait, physical functioning and patient satisfaction. RESULTS: The energy cost decreased significantly, by 8%, compared with the original KAFO. Furthermore, the incremention energy cost during walking with the carbon-composite KAFO was reduced by 18% towards normative values. An improvement in knee flexion, forward excursion of the centre of pressure, peak ankle moment, and timing of peak ankle power were significantly associated with the decrease in energy cost. Walking speed and physical functioning remained unchanged. CONCLUSION: In patients with former polio, carbon-composite KAFOs are superior to conventional leather/metal and plastic/metal KAFOs with respect to improving walking efficiency and gait, and are therefore important in reducing overuse and maintaining functional abilities in polio survivors.     

脑卒中患者步行能力与下肢三维运动学及动力学相关性分析

目的:通过对脑卒中偏瘫患者下肢三维运动学和动力学的分析,寻找偏瘫患者步态特点,比较分析步行能力与运动学和动力学之间的关系,从运动力学角度探讨偏瘫患者异常步行的原因,寻找康复治疗中需解决的关键问题。方法:选择首次脑卒中后可以独立步行10m以上的右侧偏瘫患者20例为实验组,正常健康中老年人16例为对照组。采用Vicon和AMTOR6-7进行三维步态运动学和动力学检测和分析。结果:实验组与正常对照组比较,脑卒中患者与健康中老年人在步频、跨步时间、双腿支撑时间、步时、离地比率、步长、跨步长和步速同侧比较差异有显著性意义(P<0.05),患侧离地占步态周期百分比和健侧单腿支撑时间实验组与对照组比较差异有显著性意义(P<0.05)。矢状面上同侧髋关节伸展角度、膝关节屈曲角度和踝关节背伸及跖屈角度比较差异都有显著性意义(P<0.05)。同侧髋关节屈伸力矩、同侧膝关节伸直力矩和患侧踝关节背伸力矩实验组和对照组相比差异有显著性意义(P<0.05),步行能力(步速)与患侧髋关节伸展、健侧膝关节屈曲、双侧膝关节伸展、双侧踝关节背伸和跖屈角度相关,均有显著性意义(P<0.05);同时也和双侧髋关节屈伸、膝关节伸展和踝关节背伸力矩相关(P<0.01)。结论:①步长是脑卒中偏瘫患者步态异常的重要参考指数;②髋关节和膝关节伸展,踝关节背伸和跖屈是步态异常的重要表现;③下肢髋关节和膝关节屈伸肌群和踝关节背伸肌群的力量是影响步行能力的重要因素。     

Power at hip,knee and ankle joints are compromised in women with mild and moderate knee osteoarthritis

Background

Analyses of the biomechanical characteristics of gait of women with mild and moderate knee osteoarthritis may identify parameters that could be targeted by physical therapy interventions. Therefore, the purpose of the present study was to compare the joint power profiles during gait between a group of elderly women with mild and moderate levels of knee osteoarthritis and a group of age-matched asymptomatic women.

Methods

Thirty-nine women diagnosed with osteoarthritis at the medial compartment of the knee and 39 healthy women with no diagnosis of knee osteoarthritis participated in the study. Joint power profiles of the hip, knee and ankle joints in the sagittal plane during gait were performed using video and force data obtained using Qualisys ProReflex System synchronized with two force plates. Principal component analysis was applied to extract features from the joint power waveforms characterizing their main modes of temporal variation. The extracted features were compared between groups.

Findings

Women with knee osteoarthritis absorbed and generated less energy at the hip and ankle joints, and absorbed less energy at the knee when compared to the asymptomatic group.

Interpretation

The observed power pattern in women with knee osteoarthritis may be related to their reduced gait speed, a suboptimal strategy possibly used to reduce reaction forces at the knee. Clinical studies should investigate whether interventions designed to improve muscular resources, as a means to control the flow of forces at the knee, would optimize power patterns and gait performance in women with knee osteoarthritis.     

Lower limb muscle power relationships in bilateral able-bodied gait.

OBJECTIVE: The purpose of this study was to test the hypothesis that limb propulsion is mainly associated with the interaction of a number of muscle power bursts developed throughout the stance phase and that the control actions are mainly achieved by the contralateral limb through different power-burst interactions. We also hypothesized that the power activities of the propulsion limb would be related to those of the control limb. DESIGN: Sixty gait trials of 20 subjects with dominant right hands and right legs were chosen for analysis. Each trial represents a performance of an able-bodied gait. Data were assessed using an eight-camera, high-speed, video-based system synchronized to two force plates. The muscle powers and their related mechanical energies were calculated at each joint and in each plane of the lower limbs by use of an inverse dynamic technique. The Pearson correlation method was used to determine the relationships within each limb by use of the data identified by principal component analysis, whereas a canonical correlation analysis was performed to illustrate the interaction between the limbs. RESULTS: Gait propulsion was an activity initiated by the hip shortly after heel-strike and maintained throughout the stance phase. Control was the main task of the left limb as evidenced by the power absorption bursts at the hip and knee. The left limb power generations were generally secondary to control activities and were possibly involved in adjustments to correct the other limb's propulsion. Interlimb interaction further emphasized the functional relationship between forward progression and control tasks developed by each limb and highlighted the importance of the frontal and transverse plane actions during gait. CONCLUSION: These results do not support the hypothesis that the ankle was a major contributor to forward progression.     

Effects of gait training with non-paretic knee immobilization on patients with hemiplegia: Three single-case studies

Patients’ with a hemiplegic gait and difficulties with activities of daily living may improve through intensive training of their paretic lower limbs. This study examined the possibility of improving their gait by immobilizing the non-paretic knee joint in extension and promoting weight shift toward the paretic side. Single-case ABABA studies were conducted, involving three patients with hemiplegia. The patients walked with their non-paretic knee joints immobilized in extension using a dial-lock knee orthosis during the intervention (B1 and B2) periods. Measurement items included (1) temporal and distance factors and (2) hip, knee, and ankle joint angles during gait. In all subjects, the stance phase was significantly prolonged on the paretic side during all intervention periods following the first baseline (A1) period. In Subject 1, hip extension in the stance phase improved during all intervention periods following the A1 period, and, in Subjects 2 and 3, the knee hyperextension in the stance phase, which was observed during the A1 period, was resolved during the second (A2) and third (A3) baseline periods. Gait training with non-paretic knee immobilization may promote weight shift toward the paretic side to overcome a swing limitation on the immobilized side, consequently providing an opportunity for training in weight bearing for the paretic limb and an improved, more symmetrical gait pattern.     

Biomechanical analysis of the influence of prosthetic feet on below-knee amputee walking

Although energy storing prosthetic feet have achieved widespread clinical acceptance, the effect of these components on the biomechanics of below-knee amputee gait is poorly understood. The purpose of this study was to determine the biomechanical adaptations used by the below-knee amputee while wearing a conventional prosthetic foot and to assess the influence of energy storing prosthetic feet on these adaptations. Mechanical power outputs of the lower extremity in five normal and five below-knee amputee subjects using the SACH, Seattle and Flex feet were studied. Ground reaction forces and kinematic data were collected at a walking speed of 1.5 m/s and were used to determine the muscular power outputs of the lower extremity during stance. Consistent patterns of muscular power output at the hip and knee of the residual limb occur. While wearing the SACH foot, negligible energy generation occurs at the prosthetic foot during pushoff. A decrease in energy absorption at the knee during the first half of stance and an increase in energy generation by the hip extensors were the major adaptations noted in the proximal muscle groups. Compared to the SACH foot, the energy storing feet demonstrated increased energy generation during pushoff. Despite the improvements in the performance of the energy storing prosthetic feet, no significant differences were found in the pattern or magnitude of knee and hip power outputs compared to the SACH foot.     

Compensatory advantages of toe walking

OBJECTIVES: The study's hypothesis is that toe walking requires less peak muscle strength distally about the ankle and knee compared with normal heel-toe walking and thus may have compensatory advantages for patients with upper motor neuron injury and distal muscle weakness. DESIGN: Motion analysis and force platform data were collected in able-bodied subjects during toe walking and normal walking. Sagittal plane joint torques reflecting muscle force requirements and joint powers reflecting nonisometric muscle contraction were compared between the two conditions using paired t tests, applying a Bonferroni correction for multiple comparisons. SETTING: A gait laboratory. SUBJECTS: Seventeen able-bodied adults, 9 of whom were ballet dancers. MAIN OUTCOME MEASURES: Peak hip, knee, and ankle joint torque and power variables during walking. RESULTS: Peak ankle plantarflexor torque and ankle power generation during terminal stance and preswing were reduced (p<.001), as compared with normal heel-toe walking. The normal ankle dorsiflexor torque at initial contact-and the knee extensor torque and knee power generation during loading response were all essentially absent during toe walking. Hip extensor torque and hip power generation during the loading response phase were greater for toe walking (p<.001). CONCLUSION: Toe walking may require less ankle plantarflexor, ankle dorsiflexor, and knee extensor strength than normal heel-toe walking and thus may have compensatory advantages for patients with upper motor neuron injury and distal lower extremity weakness.     

The effect of voluntary toe-walking on body propulsion

OBJECTIVE: We studied the kinetics of toe-walking by comparing the linear power flow from the leg to the upper-body. Our hypothesis was that toe-walking has no inherent biomechanical disadvantage with regard to upper-body propulsion and support. DESIGN: We studied healthy subjects capable of both heel-toe gait and voluntary toe-walking so that the two forms of gait could be directly compared. BACKGROUND: Ankle joint power at terminal stance is significantly reduced in toe-walking, which has been presumed to imply impaired propulsion and support. However, linear power analysis may be more appropriate for assessing this aspect of gait. METHODS: We compared the normal heel-toe gait of 10 healthy young adult subjects to their voluntary toe-walking gait using gait laboratory kinematic and kinetic data. Inverse dynamic analysis was performed to determine the net joint moments and joint linear powers. The contribution of each joint moment to the total hip linear power was also determined. RESULTS: Hip linear power for toe-walking was similar to that of heel-toe gait with no significant differences in the linear power peaks. The stance phase contributions of the knee and ankle moments were significantly altered in toe-walking only in early stance. CONCLUSIONS: Toe-walking does not inherently impair propulsion and support. RELEVANCE: Linear power analysis is a useful adjunct to clinical gait analysis, complementing joint power analysis. Understanding the inherent kinetics of toe-walking will enhance our analysis of pathological toe-walking and improve treatment design.     

Hemiplegic gait of stroke patients: the effect of using a cane.

OBJECTIVE: To assess the effects of cane use on the hemiplegic gait of stroke patients, focusing on the temporal, spatial, and kinematic variables. DESIGN: Case-control study comparing the effect of walking with and without a cane using a six-camera computerized motion analysis system. SETTING: Stroke clinic of a tertiary care hospital. PARTICIPANTS: Fifteen ambulatory stroke patients were analyzed, including 10 men and 5 women (mean age, 56.9 years; mean time since stroke, 9.8 weeks). Nine age-matched healthy elderly subjects were recruited as a control group. RESULTS: Stroke patients walking with a cane showed significantly increased stride period, stride length, and affected side step length, as well as decreased cadence and step width (p < .05) in comparison with those who walked without a cane. There were no significant differences in the gait phases and the five gait events of hemiplegic gait walking with or without a cane. Cane use thus may have more effect on spatial variables than on temporal variables. The affected-side kinematics of hemiplegic gait with a cane showed increased pelvic obliquity, hip abduction, and ankle eversion during terminal stance phase; increased hip extension, knee extension, and ankle plantar-flexion during preswing phase; and increased hip adduction, knee flexion, and ankle dorsiflexion during swing phase as compared with hemiplegic gait without a cane. A cane thus improved the hemiplegic gait by assisting the affected limb to smoothly shift the center of body mass toward the sound limb and to enhance push off during preswing phase. It also improved circumduction gait during swing phase. CONCLUSION: Stroke patients walking with a cane demonstrated more normal spatial variables and joint motion than did those without a cane.     

Effects of cadence on energy generation and absorption at lower extremity joints during gait

BACKGROUND: Information regarding kinetic changes associated with walking speed is important for identifying alterations in locomotor disorders caused by pathological processes, as opposed to those arising solely from altered speeds. METHODS: Fourteen healthy subjects were assessed walking at both natural and imposed cadences of 60, 80, and 120 steps/min. A 3D motion analysis system, force platforms, and related software were used to obtain kinematic and kinetic data. Net joint powers were calculated across cycles and the area under the positive and negative phases of the power curves provided the mechanical work generated and absorbed at the hip, knee, and ankle. The relative contributions to the total positive and negative work across the four cadences were calculated for each joint. ANOVAs followed by planned contrasts were used to assess the effects of laterality, joint, and cadence. FINDINGS: Power and mechanical work, as well as the contributions of individual joints to the total energy generated and absorbed, were shown to be influenced by walking cadence, independent of laterality. The ankle, knee, and hip contributions to the total limb generation and absorption at the lowest cadence were 53%, 21%, and 26%, and at the highest cadence, the corresponding values were 34%, 33%, and 33%, respectively. INTERPRETATION: Power and mechanical work, as well as the contributions of individual joints to the total energy generated and absorbed, were shown to be influenced by the walking cadence, independent of laterality. These findings will be helpful for identifying walking strategies and adaptations in populations with gait disorders.     

Compensation by nonoperated joints in the lower limbs during walking after endoprosthetic knee replacement following bone tumor resection

Background

Endoprosthetic knee replacement is often used to preserve joint function in patients with bone tumors of the distal femur or proximal tibia. Recently, because of improved oncologic outcome, surgeons are focusing more on the functional outcome of patients with musculoskeletal tumors. We hypothesized that patients who have undergone endoprosthetic knee replacement are forced to compensate for deficiency in their operated joint during walking. In this study, we investigated differences in gait kinematics, kinetics, and energetics between patients with endoprosthetic knee replacement and healthy subjects.

Methods

We performed gait analysis for 8 patients who underwent endoprosthetic knee replacement after bone tumor resection and 8 matched healthy subjects. Gait kinematics, kinetics, and energetics of patients' ipsilateral and contralateral limbs were compared with those of healthy subjects by using Dunnett's test.

Findings

Compared with healthy subjects, patients showed increased negative joint power around the ipsilateral ankle, greater second peak in the contralateral vertical ground reaction forces, and abnormal hip movement on both sides after initial contact.

Interpretation

Patients tended to compensate for dysfunction of the reconstructed knee by muscles around the ipsilateral ankle and contralateral hip, with increased load on the contralateral limb during walking. These differences could lead to secondary impairments. Further analysis, including musculoskeletal simulation and assessment of long-term functional outcome with regard to secondary musculoskeletal impairment, is needed to verify the significance of the change in gait and to determine the need for special care for secondary musculoskeletal dysfunction in these patients.     

Bilateral accommodations to anterior cruciate ligament deficiency and surgery

OBJECTIVE To determine bilateral lower extremity joint accommodations during gait in anterior cruciate ligament deficient subjects and uninjured controls. DESIGN: Gait testing of 10 chronic anterior cruciate ligament deficient subjects prior to and 3 months following reconstructive surgery, and 10 uninjured controls. BACKGROUND: It is possible that bilateral joint accommodations could occur as a result of anterior cruciate ligament injury and in response to surgical repair. Few studies have investigated bilateral joint accommodations to anterior cruciate ligament injury and there is little consistency in the reported results. METHODS: Bilateral lower extremity kinematic and kinetic data were collected from 12 walking trials and inverse dynamics calculations were made to estimate bilateral knee and hip joint angle, moment, and power patterns during the stance phase of gait. RESULTS: Control subjects exhibited asymmetrical hip but symmetrical knee joint moment and power patterns. In contrast, the anterior cruciate ligament deficient subjects exhibited symmetrical hip and asymmetrical knee joint moment and power patterns prior to and following reconstructive surgery. CONCLUSIONS: Gait asymmetry in healthy subjects should not be considered pathological. In addition, chronic anterior cruciate ligament injury results in joint specific, bilateral lower extremity accommodations in gait mechanics. These accommodations persist 3 months following surgical repair.     

Short term outcomes of hip arthroscopy on hip joint mechanics and cartilage health in patients with femoroacetabular impingement syndrome

BackgroundFemoroacetabular acetabular impingement syndrome consists of abnormal hip joint morphology resulting in painful hip joint impingement. Hip arthroscopy corrects the abnormal morphology and reduces clinical symptoms associated with femoroacetabular impingement syndrome yet the effects of hip arthroscopy on gait mechanics and cartilage health are not well understood.MethodsTen femoroacetabular impingement syndrome patients and 10 matched asymptomatic controls underwent gait analysis consisting of three-dimensional hip joint kinematics and kinetics. Femoroacetabular impingement syndrome patients underwent gait analysis and quantitative magnetic resonance imaging of the surgical hip joint before and seven months post-surgery. Patient reported outcomes were obtained from all study participants and were used to quantify hip joint pain, function and quality of life.FindingsPrior to surgery, femoroacetabular impingement syndrome patients demonstrated hip joint kinematics or kinetics as the control group. After surgery, femoroacetabular impingement syndrome patients exhibited improved patient reported outcomes, similar hip joint kinematic patterns, increased hip flexion and decreased hip extension moment impulses within the surgical limb. The femoroacetabular impingement syndrome patients that ambulated with increased HFMI post-surgery demonstrated a decrease in femoral cartilage T1ρ and T2 values.InterpretationFemoroacetabular impingement syndrome patients exhibited improved clinical symptoms yet ambulated with altered sagittal plane hip joint loading after hip arthroscopy. Increased hip flexion moment impulse post-surgery was associated with improved cartilage health within the surgical limb. These study findings suggest that sagittal plane hip joint loading at short-term follow-up after hip arthroscopy is associated with cartilage health and may be an important biomechanical parameter in post-operative rehabilitation programs.