Validity and sensitivity to change of three scales for the radiographic assessment of knee osteoarthritis using images from the Multicenter Osteoarthritis Study (MOST).

OBJECTIVES: The purpose of this study was to assess the concurrent validity and sensitivity to change of three knee osteoarthritis (OA) grading scales. The Kellgren-Lawrence (KL) and the Osteoarthritis Research Society International (OARSI) joint space narrowing (JSN) grading scales are well-established. The third scale, the compartmental grading scale for OA (CG) is a novel scale which grades JSN, femoral osteophytes, tibial erosion and subluxation to create a total score. METHODS: One sample of 72 posteroanterior (PA) fixed-flexion radiographs displaying mild to moderate knee OA was selected from the Multicenter Osteoarthritis Study (MOST) to study validity. A second sample of 75 radiograph pairs, which showed an increase in OA severity over 30 months, was selected to study sensitivity to change. The three radiographic grading scales were applied to each radiograph in both samples. Spearman's rank correlation coefficients were used to correlate the radiographic grades and the change in grades over 30 months with a Whole-organ Magnetic Resonance Imaging Score (WORMS)-based composite score which included five articular features of knee OA. RESULTS: Correlations between the KL, OARSI JSN and CG grading scales and the magnetic resonance image (MRI)-based score were 0.836, 0.840 and 0.773 (P < 0.0001) respectively while correlations between change in the radiographic grading scales and change in the MRI-based score were 0.501, 0.525 and 0.492 (P < 0.0001). CONCLUSIONS: All three radiographic grading scales showed high validity and are suitable to assess knee OA severity. They showed moderate sensitivity to change; therefore caution should be taken when using ordinal radiographic grading scales to monitor knee OA over time.

Standardized standing pelvis-to-floor photographs for the assessment of lower-extremity alignment.

OBJECTIVES: The objective of this cross-sectional study was to assess the intra-rater, inter-rater and test-retest reliability and concurrent validity of lower-extremity alignment estimated from a photograph [photographic alignment (PA) angle]. METHODS: A convenience sample of participants was recruited from the community. Radiopaque stickers were placed over participants' anterior superior iliac spines. One radiograph and one photograph were taken with the participant standing in a standardized position. The stickers were removed. After 30 min they were reapplied and a second photograph was taken. The hip-knee-ankle (HKA) angle was measured from each radiograph using customized imaging analysis software. The same software was used by three readers to measure the PA angle from each photograph from the first set twice, at least 2 weeks apart. One reader measured the PA angle from the second set of photographs. Reliability was tested using intraclass correlation coefficients (ICC(2,1)), Bland-Altman analyses and the minimal detectable change (MDC95). Concurrent validity was tested using a Pearson's correlation coefficient and Bland-Altman analysis. RESULTS: Fifty adults participated (mean age 41.8 years; mean body mass index 24.7 kg/m(2)). The PA angle was 4.5° more varus than the HKA angle; these measures were highly correlated (r = 0.92). Intra-rater (ICC(2,1) > 0.985), inter-rater (ICC(2,1) = 0.988) and test-retest reliability (ICC(2,1) = 0.903) showed negligible bias (<0.20°). The MDC95 was 2.69°. CONCLUSIONS: The PA angle may be used in place of the HKA angle if a bias of 4.5° is added. A difference of 3° between baseline and follow-up would be considered a true difference.

Falls and injury prevention should be part of every stroke rehabilitation plan.

OBJECTIVE: To evaluate falls incidence, circumstances and consequences in people who return home after stroke rehabilitation, so that appropriate falls and injury prevention strategies can be developed. DESIGN: Prospective cohort study. SETTING: Community. SUBJECTS: Fifty-six subjects with stroke who were participating in a rehabilitation programme and returning to live in a community setting completed the study. MAIN MEASURES: Subjects completed a prospective falls diary for six months after discharge from rehabilitation, and were interviewed after falls. Physical function was measured by the Berg Balance Scale (BBS) and the Functional Independence Measure (FIM). RESULTS: Forty-six per cent of people (26/56) fell, with most falls (63/103 falls) occurring in the two months after discharge from rehabilitation. One subject had 37 similar falls and these falls were excluded from further analysis. Falls occurred more often indoors (50/66), during the day (46/66) and towards the paretic side (25/66). People required assistance to get up after 25 falls (38%) and 36 falls (55%) resulted in an injury. People sought professional health care after only 16 falls, and activity was restricted after 29 falls (44%). The Berg Balance Scale and Functional Independence Measure scores were lower in people who had longer lies after a fall, and who restricted their activity after a fall (p < 0.05). Lower physical function scores were also associated with falling in the morning, wearing multifocal glasses at the time of a fall, and injurious falls (p < 0.05). CONCLUSION: Falls are common when people return home after stroke. Of concern are the small number seeking health professionals' assistance after a fall, the high proportion restricting their activity as a result of a fall and the number of falls occurring towards the paretic side.

Three-dimensional kinematic and kinetic analysis of the hip and knee joints during the stepping exercise in older subjects

O exercicio com o step e uma atividade aerobica normalmente indicada em programas de reabilitacao para idoso. O efeito biomecanico desse exercicio nas articulacoes do quadril e do joelho de pessoas idosas ainda nao foi estudado. Objetivo: Quantificar a cinematica e a cinetica do quadril e do joelho em tres dimensoes durante a atividade de step em participantes acima de 55 anos de idade. Metodo:dados de 9 participantes (media de 64,8 anos) foram coletados. Os dados foram obtidos por meio do sistema Optotrak acoplado a uma plataforma de forca e de raios-X padronizados para determinar com precisao os centros de rotacao das articulacoes e dos dados antropometricos. A altura do step era de 16 cm e estava localizado em frente a plataforma de forca. Resultados: as articulacoes de quadril e joelho geraram maiores momentos internos de forca abdutora de...

Radiographic and non-invasive determination of the hip joint center location: Effect on hip joint angles

A localizacao do centro de rotacao do quadril e importante na analise dos dados cinematicos da marcha. Metodos acurados para localizacao do centor de articulacao envlovem tecnicas invasivas e de alto custo. O objetivo deste trabalho foi obter angulos no quadril durante a marcha, usando quatro metodos nao-invasivos de estimar o centro de rotacao do quadril, e comparar com angulos obtidos usando tecnica radiografica QPR. Dez sujeitos sadios, entre 57 e 73 anos de idade, participaram do estudo. As tecnicas nao-invasivas usam distancias entre proeminencias osseas localizadas na pele e no quadril para estimas o centro de rotacao do quadril. As radiografias no plano frontal obtidas usando o OPR fornecem com precisao a localizacao do centro de rotacao do quadril nas direcoes medio-laterais e proximo-distais. O metodo mais acurado de estimar a localizacao do centro de rotacao do quadril foi determinado o ponto medio de uma limha conectando a espinha iliaca direita anterior-superior e a sinfise pubica, e movendo essa linha 2 cm inferiormente. Essa tecnica estimou o centro de rotacao do quadril 0,7 cm medial e 0,8 cm superior a sua localizacao, como determinado pela tecnica do QPR. Os angulos obtidos no quadril durante ciclo da marcha usando esse metodo gerou erros inferiores 2º em cada plano, quando comparado com o QPR. O s resultado deste estudo indicam que esse metodo nao-invasivo e de baixo custo e valido para estimar o centro de rotacao do quadril em estudos de analise de marcha.

A self-administered pain severity scale for patellofemoral pain syndrome.

OBJECTIVE: To develop a scale for estimating the severity of patellofemoral pain syndrome (PFPS) and to determine its reliability and validity. DESIGN: The PFPS Severity Scale (PSS) was developed following a literature search, input from clinicians, and pilot testing in people with PFPS. The final version of the instrument encompasses 10 statements regarding PFPS pain in a visual analogue format. Reliability and validity of the new scale were determined in a PFPS population. SETTING: All testing was performed at the Canadian Forces Base Kingston, Physiotherapy Department. SUBJECTS: Twenty-nine military subjects (7 female) between the ages of 20 and 48 (32 years +/- 8.9) with subjective and objective findings consistent with PFPS were recruited. Twenty-four of the participants (6 female, 31.8 years +/- 9.4) participated in the reliability phase of the study. METHODS: Reliability of the PSS was determined by comparing the scores obtained on two test days (24 hours apart). Convergent validity of the PSS was determined by comparing data from the PSS with two established knee scales: the WOMAC (Western Ontario and McMaster Universities) Osteoarthritis Index and the Hughston Foundation subjective knee scale. RESULTS: Test-retest reliability was excellent (Spearman's rho = 0.95, p < 0.0001). The correlations between the PSS and the WOMAC and Hughston scales were strong (rho = 0.72 and 0.83, p < 0.001 respectively). CONCLUSIONS: The PSS is reliable and has demonstrated convergent validity making it a useful tool for monitoring rehabilitative or surgical outcomes in clients with PFPS.

Use of visual feedback in retraining balance following acute stroke.

BACKGROUND AND PURPOSE: Visual feedback related to weight distribution and center-of-pressure positioning has been shown to be effective in increasing stance symmetry following stroke, although it is not clear whether functional balance ability also improves. This study compared the relative effectiveness of visual feedback training of center-of-gravity (CoG) positioning with conventional physical therapy following acute stroke. SUBJECTS: Forty-six people who had strokes within 80 days before the study, resulting in unilateral hemiparesis, and who were in need of balance retraining participated. METHODS AND MATERIALS: Initially, subjects were randomly assigned to visual feedback or conventional physical therapy groups for balance retraining until 16 subjects per group were recruited. The next 14 subjects were assigned to a control group. All subjects received physical therapy and occupational therapy (regular therapy) 2 hours a day, and subjects in the 2 experimental groups received additional balance training 30 minutes a day until discharge. The visual feedback group received information about their CoG position as they shifted their weight during various activities. The conventional therapy group received verbal and tactile cues to encourage symmetrical stance and weight shifting. Static (postural sway) and activity-based measures of balance (Berg Balance Scale, gait speed, and the Timed "Up & Go" Test) were contrasted across the 3 groups at baseline, at discharge, and at 1 month following discharge using an analysis of variance for repeated measures. RESULTS: All groups demonstrated marked improvement over time for all measures of balance ability, with the greatest improvements occurring in the period from baseline to discharge. No between-group differences were detected in any of the outcome measures. CONCLUSION AND DISCUSSION: Visual feedback or conventional balance training in addition to regular therapy affords no added benefit when offered in the early stages of rehabilitation following stroke.

Resistance to passive shoulder external rotation in persons with hemiplegia: evaluation of an assessment system.

OBJECTIVES: To determine the LIDO Active System's reliability and validity in measuring resistance to passive external rotation (RPER) of the shoulder in subjects who have sustained a cerebrovascular accident (CVA). STUDY DESIGN: Twenty hemiplegic subjects, between the ages of 38 and 78 yrs, participated in the study; 14 agreed to be tested on two occasions, for the reliability phase of the study. OUTCOME MEASURES: RPER, measured by the LIDO Active system; tone in the internal rotator musculature, measured by the Ashworth Scale; and shoulder external rotation range of motion, measured by a standard goniometer. RESULTS: Test-retest reliability of RPER measured on the LIDO system was demonstrated with intraclass correlation coefficients of .95 and .67 on the affected and nonaffected limb, respectively. Differences in RPER between the affected and nonaffected limb were significant (p<.01) and RPER on the affected limb correlated significantly with Ashworth measures of muscle tone (Spearman's rho = .62). CONCLUSION: The LIDO Active System provided reliable and valid measures of RPER of the shoulder in hemiplegic subjects. The LIDO system may be a useful device for objective measurement of the effectiveness of medical and rehabilitation interventions designed to bring muscle tone into the normal range and decrease contracture in the shoulder musculature.

Hip moments during level walking, stair climbing, and exercise in individuals aged 55 years or older.

BACKGROUND AND PURPOSE: Low bone mass of the proximal femur is a risk factor for hip fractures. Exercise has been shown to reduce bone loss in older individuals; however, the exercises most likely to influence bone mass of the proximal femur have not been identified. Net moments of force at the hip provide an indication of the mechanical load on the proximal femur. The purpose of this study was to examine various exercises to determine which exercises result in the greatest magnitude and rate of change in moments of force at the hip in older individuals. SUBJECTS AND METHODS: Walking and exercise patterns were analyzed for 30 subjects (17 men, 13 women) who were 55 years of age or older (X = 65.4, SD = 6.02, range = 55-75) and who had no identified musculoskeletal or neurological impairment. Kinematic and kinetic data were obtained with an optoelectronic system and a force platform. Results. Of the exercises investigated, only ascending stairs generated peak moments higher than those obtained during level walking and only in the transverse plane. Most of the exercises generated moments and rate of change in moments with magnitudes similar to or lower than those obtained during gait. CONCLUSION AND DISCUSSION: Level walking and exercises that generated moments with magnitudes comparable to or higher than those obtained during gait could be combined in an exercise program designed to maintain or increase bone mass at the hip.

Radiographic and non-invasive determination of the hip joint center location: effect on hip joint moments.

OBJECTIVE: To determine which of four non-invasive measures is most accurate in locating the hip joint center. BACKGROUND: The location of the joint centers must be accurately determined in three dimensions for calculation of the moments of force during gait. It is not known which of the several non-invasive methods available for location of the hip center is most accurate. DESIGN: Hip center location was determined using standardized X-rays and four non-invasive methods which utilized measured distances between bony landmarks in 10 healthy subjects. Hip moments during gait were obtained from optical tracking, force plate and anthropometric data. RESULTS: The most accurate non-invasive method of locating the hip center was by taking the midpoint of a line connecting the antero-superior iliac spine and the symphysis pubis and moving inferiorly 2 cm. Using this approach the hip center was located 0.7 cm medial and 0.8 cm superior to its true location determined using the standardized X-rays. The 95% confidence interval of the maximum error difference in moments measured between this method and the standardized X-rays ranged from -0.15 to 0.4 Nm/kg in the frontal plane, -0.03 to 0.07 Nm/kg in the sagittal plane and -0.05 to -0.03 Nm/kg in the transverse plane. CONCLUSIONS: Locating the hip center based on the distance between the antero-superior iliac spine and the symphysis pubis is a valid technique for estimating the hip center in routine gait analysis.

Lower-extremity muscle force and balance performance in adults aged 65 years and older.

BACKGROUND AND PURPOSE: Measures of postural control may be useful for determining fall risk in older people and for determining the outcomes of treatments aimed at improving balance. Commonly used tools measure the output of the postural control system. The purpose of this study was to determine the degree to which one component of postural control (muscle force) contributes to scores on 3 functional balance measures. SUBJECTS: Fifty community-dwelling volunteers between 65 and 91 years of age (mean = 74.82, SD = 6.11) participated. Based on their histories, 11 subjects were classified as being at risk for falling. METHODS: Measures were the Berg Balance Scale (BBS), the Functional Reach Test (FRT), and the Timed Get Up & Go Test (GUG). The force generated by 12 lower-extremity muscle groups was measured using a handheld dynamometer. RESULTS: In the group reporting no falls, dorsiflexor and subtalar evertor force accounted for 58% of the score on the BBS, ankle plantar-flexor and subtalar invertor force accounted for 48.4% of the score on the GUG, and ankle plantar-flexor force accounted for 13% of the score on the FRT. Ankle dorsiflexor and hip extensor forces were lower in subjects reporting falls, and force of the ankle dorsiflexors predicted fall status. CONCLUSION AND DISCUSSION: Distal muscle force measures may be able to contribute to the prediction of functional balance scores; however, the muscles involved in the prediction differ depending on the measure of balance.

Normal variability of postural measures: implications for the reliability of relative balance performance outcomes.

The reliability of outcome measures obtained using the Balance Master and the limits of stability in anterior, posterior, and lateral directions were evaluated in 70 healthy subjects aged 20 to 32 years. Data relating to static sway and the ability to shift the centre of gravity to preset targets were collected on three occasions one week apart. The centre of gravity position and limits of stability were determined over three trials and data converted from a relative reference system to absolute displacements from vertical. Intraclass correlation coefficients revealed fair to poor reliability of static and dynamic sway measures (coefficients < or = 0.55) and excellent reliability of limits of stability measures and the position of the centre of gravity (coefficients > or = 0.75). The variability in outcome measures from tests which do not maximally challenge the postural control system may be a hallmark of normal balance performance. Further, the intersubject variation in resting centre of gravity position and in limits of stability supports the use of absolute performance measures as the interpretive value of data expressed relative to standard norms is limited.

Comparison of five isometric exercises in the recruitment of the vastus medialis oblique in persons with and without patellofemoral pain syndrome.

Strengthening of the vastus medialis oblique (VMO) has been advocated as a treatment for patellofemoral pain syndrome (PFPS), as weakness of this component of the quadriceps is postulated to contribute to malalignment of the patella. This study investigated the surface electromyographic activity (EMG) of the VMO relative to the vastus lateralis (VL) during five isometric exercises in eight PFPS female subjects and 19 controls. The area under the EMG curve of each muscle was normalized to the EMG area acquired while subjects performed a submaximal isometric contraction (50% of maximum voluntary contraction), and the "normalized" outcome measure was expressed as a proportion (VMO:VL). A two-factor repeated measures analysis of variance indicated no differences in the VMO:VL proportion between the control group and PFPS participants across the five exercises (p > .05). The VMO:VL proportions for medial tibial rotation and knee extension combined and knee extension alone were significantly greater than for the other three exercises (p < 0.005). Hip adduction or the combination of hip adduction and knee extension did not result in greater recruitment of the VMO compared with the VL.

Balance and skeletal alignment in a group of elderly female fallers and nonfallers.

The purpose of this study was to determine whether sagittal plane posture differed between fallers and nonfallers and to explore the relationship between skeletal alignment and balance in elderly females. Forty-eight women > 65 years of age were recruited from various medical and senior citizen centers. Thirteen of these women were classified as fallers. Spinal posture was measured in standing using an inclinometer, and lower extemity joint angles were assessed in standing using a universal goniometer. The Berg Balance Scale, the Functional Reach Test, end a modified Timed Get Up and Go Test were used to measure balance. Spinal alignment did not differ significantly between fallers and nonfallers; however, knee joint angle was significantly greater in fallers compared to nonfallers. Significant, but low, correlations were found between the inclination of the upper thoracic spine and all three balance measures. Lower thoracic slope and knee joint angle in standing were also weakly related to two of the three balance measures. This study supports the hypothesis that a significant but weak relationship exists between balance and skeletal alignment in elderly females.

The effect of initial head position on active cervical axial rotation range of motion in two age populations.

STUDY DESIGN: This study analyzed cervical axial rotation initiated from five different starting positions in asymptomatic subjects. The results were analyzed to ascertain if rationale for certain clinical assessment methods could be justified. SUMMARY OF BACKGROUND DATA: In the assessment of the cervical spine, many clinicians use assessment techniques that propose to isolate anatomic structures by using various permutations and combinations of the three gross rotational movements, for example, evaluation of axial rotation in flexion and extension. OBJECTIVES: The primary purpose of this study was to compare the magnitude of cervical axial rotation when started from neutral, flexion, extension, protraction, and retraction, and the protraction-retraction range of motion also was determined. METHODS: Two groups of 30 subjects, one group aged 18-30 years and the other group aged 50-65 years and stratified by gender, participated in the study. The 3Space Tracker system (Polhemus, A Kaiser Aero-space and Electronics, Co., Colchester, VT), art electromagnetic tracking device, was used to determine the angular and linear position of the head relative to the sternum by detecting the position and orientation of two sensors attached to the forehead and sternum. RESULTS: Analysis of variance of the data revealed a statistically significant difference (p < 0.05) in axial rotation between all of the five starting positions. The younger age group demonstrated greater range of motion when rotation was initiated from neutral and extension, whereas the older group had greater range when the motion was initiated from protraction, retraction, and flexion. CONCLUSIONS: The results suggest that varying the starting sagittal head position may affect the anatomic structures involved in restraining axial rotation. This supports the clinical approach to range of motion assessment in combined movement patterns.

Shoulder complex position and glenohumeral subluxation in hemiplegia.

OBJECTIVES: 1. To determine if scapular and humeral orientation differed between the affected and nonaffected side in two groups of hemiplegic subjects (low tone and high tone). 2. To determine if there was a relationship between these measures and glenohumeral subluxation in either group. DESIGN: Retrospective case-comparison study. SUBJECTS, SETTING: Thirty-four hemiplegic subjects, 41 to 89 years of age, participated in the study. Subjects were divided into high-tone (n = 17) and low-tone (n = 17) groups on the basis of Ashworth scoring of muscle tone. OUTCOME MEASURES: Linear and angular measures of scapular and humeral orientation were calculated from tridimensional coordinates of bony landmarks collected using an electromagnetic device with subjects in a seated position with arms relaxed by their side. Glenohumeral subluxation was measured from radiographs. RESULTS: The scapula was further from the midline and lower on the thorax on the affected side in the low-tone group (p < .05). Glenohumeral subluxation was greater in the low-tone group (p < .05). The scapular abduction angle (ScAb) was significantly greater on the nonaffected in the low-tone group compared with both the affected side in this group and to the nonaffected side in the high-tone group. In the high-tone group, no differences were found between the affected and nonaffected side in either the angular or linear measures. There was no significant correlation between scapular or humeral orientation and glenohumeral subluxation in either group (p > .05). CONCLUSIONS: This study provided little evidence of a consistent pattern of alteration in shoulder complex orientation, particularly in subjects with increased muscle tone, and no support for the concept of a relationship between scapular and humeral orientation and glenohumeral subluxation.

Thoracic kyphosis, rib mobility, and lung volumes in normal women and women with osteoporosis.

STUDY DESIGN: Lung volumes and rib mobility were measured in 15 women with kyphosis resulting from spinal osteoporosis and in 15 healthy women. OBJECTIVES: The study first sought to determine the relationship between thoracic kyphosis and rib mobility and then sought to determine the effect of kyphosis and associated changes in rib mobility on respiratory function. SUMMARY OF BACKGROUND DATA: Spinal deformity in ankylosing spondylitis and scoliosis is associated with alterations in respiratory function. The effect of thoracic kyphosis on respiratory mechanics has not been investigated in an osteoporotic population. METHODS: Lung volumes were measured using a spirometer, and rib mobility, during maximal inspiratory and expiratory maneuvers, was monitored with four motion sensors placed anteriorly, posteriorly, and laterally on the thorax. RESULTS: Vital capacity, inspiratory capacity, total lung capacity, and lateral expansion of the thorax were lower in the osteoporotic group (P < 0.05). There was a significant negative correlation between kyphosis angle and inspiratory capacity, vital capacity, and lateral expansion of the thorax. CONCLUSIONS: Lung volumes and rib mobility were significantly impaired in women with thoracic kyphosis.

Functional anatomy of the shoulder complex.

Recent research findings are incorporated in this review of the functional anatomy of the shoulder complex. The scapulothoracic mechanism is described, including a review of scapular motion and the structure and function of the sternoclavicular and acromioclavicular joints. New information regarding the resting position of the scapula on the thorax and the effect of aging and spinal posture on position has been presented. In the second part of the paper, the anatomy of the glenohumeral joint is reviewed, with emphasis on the articular, periarticular, and muscular mechanisms responsible for stability of this articulation. The article concludes with a discussion of the integrated function of the scapulothoracic and glenohumeral articulations in upper extremity elevation.

Validation of outcome measures in patients with patellofemoral syndrome.

This project was supported by a grant from the Physiotherapy Foundation of Canada. The purpose of this study was to determine the reliability and validity of the following outcome measures in a group of 18 patients with patellofemoral pain syndrome: the visual analog pain scale (VAS), a functional index questionnaire (FIQ), selected temporal components of gait on level walking and ascending stairs, knee joint angle on downhill walking, and electromyographic activity of the quadriceps during stair climbing. Subjects were tested at initial assessment (time 0), after 24 hours (time 1), and after clinically significant improvement, following a course of treatment (time 2). Using the intraclass correlation coefficient (r1), the VAS (r1 = 0.603) and FIQ (r1 = 0.483) exhibited poor day-to-day reliability (time 0 versus time 1). However an ANOVA between time 0 and time 2 showed them to be valid measures for detection of clinical change (p < 0.01). No differences in the gait variables were observed from time 0 to time 1 or time 2, suggesting that gait analysis may not be sensitive enough to detect changes in pain and function in this patient population. J Orthop Sports Phys Ther 1989;10(8):302-308.

Below-knee amputation: a comparison of the effect of the SACH foot and single axis foot on electromyographic patterns during locomotion.

The purpose of this investigation was to measure the effect of two terminal prosthetic components, the SACH foot and the single axis foot, on the locomotion patterns of unilateral below-knee amputees. The ten subjects who participated in the study were evaluated on two occasions, once following prescription of a PTB prosthesis and one terminal device and once following its replacement with the second device. The two devices were allocated alternately at the time of prosthetic prescription to ensure that five of the subjects used the SACH foot initially and five used the single axis foot. The electromyographic activity of the vastus lateralis and medial hamstrings was recorded bilaterally during gait using Beckman surface electrodes. The EMG signals were full wave rectified and low pass filtered to obtain the linear envelope. Pressure sensitive foot-switches were used to correlate the EMG signals with components of the gait cycle. The pattern of quadriceps and hamstring muscle activity of the contralateral limb was similar to that reported for normal individuals and was unaffected by changing the terminal device on the prosthetic limb. The pattern of quadriceps and hamstring activity of the prosthetic limb differed from that of the contralateral limb and was influenced by the change in terminal device. With both devices the muscles were active for a greater percentage of the stance phase when compared to the contralateral limb. With the SACH foot attachment there appeared to be more contraction of the quadriceps and hamstrings during the mid stance phase of gait.