Comparison of the Lumbar Flexion Angle and EMG Activity in Trunk Muscles in Individuals with and without Limited Hip Flexion Range of Motion during Visual Display Terminal Work with Cross-Legged Sitting

[Purpose] The purpose of this study was to compare the lumbar flexion angle and electromyography (EMG) measurements of trunk muscle activity in individuals with and without limited hip flexion range of motion (ROM) during visual display terminal (VDT) work with cross-legged sitting. [Subjects] The 15 participants included a control group with sufficient hip flexion ROM (n = 7) and an experimental group with limited hip flexion ROM (n = 8). [Methods] All subjects performed VDT work with cross-legged sitting. The lumbar flexion angle was measured using a three-dimensional motion capture system, and the trunk muscle activity was recorded using a surface EMG system during VDT work with cross-legged sitting. The differences in trunk flexion angle and trunk muscle activity between the two groups were analyzed using independent t-tests. [Results] The lumbar flexion angle was significantly greater in the experimental group than the control group, although trunk muscle activity did not differ between the two groups. [Conclusion] These findings suggest that limited hip flexion leads to greater lumbar flexion during cross-legged sitting.Key words: Cross-legged sitting, Electromyography, Lumbar flexion     

Radiographic verification of knee goniometry

The accuracy of knee goniometry was examined by comparing goniometric measurements with radiographic bone angle measurements of six positions of the knee, namely, 0 degree, 15 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees. Within the first 15 degrees of knee flexion joint excursion measured by goniometry differed significantly from bone angle measurement (p less than 0.01). With 30 degrees of knee flexion or more, no significant difference was found between goniometric measurements and bone angle measurements of knee motion. These findings suggest that within the first 15 degrees of knee flexion, goniometric measurement of joint excursion may be remarkably wrong. On account of this, it was suggested that when range of motion is limited at the knee joint, caution should be exercised in determining movement gains or losses within the initial 15 degrees of knee flexion.     

Influence of knee flexion on isometric hip extensor strength

The maximum isometric extensor muscle strength was measured in 10 healthy subjects of different combinations of hip and knee angles. An ordinary exercise device was used for the measurements and the method could be useful in clinical work. The results revealed that the knee angle does not affect the hip extensor strength. The highest extensor muscular moments occurred at 90 degrees hip flexion, decreasing with decreasing hip angle. The distribution of the strength over the motion sector differed between male and female. The weight of the body segments was found to utilize 10-24% of the maximum strength at hip angles 60 degrees-0 degrees with subjects in a prone position.     

Limitations in activities in patients with osteoarthritis of the hip or knee: The relationship with body functions,comorbidity and cognitive functioning

Purpose. To determine the relationship between body functions, comorbidity and cognitive functioning on the one side and limitations in activities on the other, in elderly patients with osteoarthritis (OA) of the hip or knee.

Method. A cross-sectional cohort study was conducted in which 288 patients with hip or knee OA were included. Patients were recruited from rehabilitation centres and hospitals (Departments of Orthopedics, Rheumatology or Rehabilitation). Apart from demographic and clinical data, information about limitations in activities, body functions (pain, muscle strength, range of joint motion), comorbidity and cognitive functioning was collected by questionnaires and tests. Statistical analyses included univariate and stepwise multivariate regression analysis.

Results. Self-reported limitations in activities (Western Ontario and McMaster Universities Osteoarthritis Index) were significantly associated with pain, muscle strength knee extension, range of motion (ROM) hip flexion and morbidity count. Performance-based limitations in activities (timed walking test) were significantly associated with ROM (knee flexion, hip flexion and knee extension), muscle strength hip abduction, pain, cognitive functioning and age.

Conclusions. Self-reported limitations in activities in hip or knee OA are largely dependent on pain and to a lesser extent on range of joint motion, muscle strength and comorbidity. Performance-based limitations in activities are largely dependent on range of joint motion and muscle strength, and to a lesser extent on pain, cognitive functioning and other factors. These findings point to the role of body functions in limitations in activities in OA of the hip or knee. Although less important, comorbidity and cognitive functioning play a role as well.     

Inter-rater reliability of DartfishTM movement analysis software for measuring maximum flexion and extension at the hip and knee in older adults with osteoporosis and osteopenia

Various methods are used to measure hip and knee joint motion angles; however, their use is often limited by cost or inability to measure dynamic movements. The assessment of movement patterns is clinically useful in individuals with osteoporosis (OP) and osteopenia (OPe) through its potential to optimize fracture risk assessment. This study evaluates the inter-rater reliability of using Dartfish^TM 2-D Motion Analysis Software to measure maximum flexion and extension angles at the hip and knee in individuals with OP or OPe while performing five tasks of the Safe Functional Motion test. Twelve participants were videotaped performing the pour, footwear, newspaper, sweep, and sit-to-floor tasks. Five raters used Dartfish^TM to analyze maximum flexion and extension angles at the hip and knee, and an intra-class correlation coefficients (ICC) and SEM were calculated for each measurement. In all five tasks, ICC and SEM values ranged from 0.23 to 0.95, and 1.75 to 11.54 degrees, respectively, with maximum knee flexion angles generally having higher ICC, and lower SEM point estimates. The results indicate that Dartfish^TM measurements of maximum knee flexion angles in uniplanar tasks demonstrate a moderate to excellent degree of inter-rater reliability, while measurements at the hip joint should be used with caution. Given that the results of this study display moderate to excellent reliability, they lay the groundwork for future research aimed at determining the validity of these measurements. Such research would help to further develop the base of evidence surrounding the usefulness of Dartfish^TM Motion Analysis in fracture risk analysis among individuals with OP.     

Co-contraction during passive movements of the knee joint in children with cerebral palsy

BACKGROUND: Co-contraction is an impairment commonly reported in children with cerebral palsy. However, co-contraction has not been investigated during passive movements which may be used to assess spasticity in children with cerebral palsy. The purpose of this study was to examine the frequency of co-contraction and the relationship between reflex activity and co-contraction during passive movements of the knee joint in children with cerebral palsy. METHODS: Twenty children with cerebral palsy participated in this study. One set of ten continuous passive movements from 90 degrees of knee flexion to 25 degrees of knee flexion and from 25 degrees of knee flexion to 90 degrees of knee flexion was completed at 15 degrees /s, 90 degrees /s, and 180 degrees /s. The mean percentage of the range of motion of each movement and mean percentage of the number of movements which exhibited electromyographic activity of the vastus lateralis, medial hamstrings, and co-contraction were calculated for each set of movements. FINDINGS: The number of the movement repetitions and the percentage of the range of motion which exhibited co-contraction were considerable regardless of the direction and speed of motion. Significant positive correlations were found between the percentage of the passive range of motion with medial hamstrings activation, vastus lateralis activation, and co-contraction during passive movements into both knee flexion and knee extension at a velocity of 15 degrees /s, 90 degrees /s, and 180 degrees /s (P<0.001). INTERPRETATION: Co-contraction commonly occurs during passive movements of the knee in children with cerebral palsy. The presence of co-contraction may influence measurements of spasticity which use passive movements to assess spasticity.     

Intrinsic and imposed hamstring length influence posterior pelvic rotation during hip flexion

BACKGROUND: The contribution of posterior tilt of the pelvis (pelvic rotation) to hip flexion has been described for individuals who are standing, supine, and suspended. The effects of intrinsic and imposed hamstring length on the motion have not been investigated in a controlled manner. This study investigated the influence of intrinsic and imposed hamstring length on pelvic rotation during bilateral active hip flexion. METHODS: Intrinsic hamstring length was characterized by the maximal active straight leg raise angle. Hamstring length was imposed by immobilizing the knees in 0 degrees, 45 degrees, and 90 degrees of flexion. Pelvic and thigh segments were marked with reflective spheres. Subjects' saggital plane motion was captured using computerized motion analysis during bilateral hip flexion while both knees were immobilized in three positions. Multifactorial analysis of variance was employed to show the effect of intrinsic and imposed hamstring length on pelvic rotation. FINDINGS: Pelvic rotation occurred throughout the hip flexion range of motion. Pelvic rotation was influenced significantly by hip flexion angle, knee position, the interaction between hip flexion angle and knee position, and the interaction between hip flexion angle, knee position, and active straight leg raise angle. INTERPRETATION: Both intrinsic and imposed hamstring length influence pelvic rotation during bilateral hip flexion. These influences should be considered by clinicians who have individuals engage in hip flexion maneuvers.     

Speed variation and resultant joint torques during sit-to-stand

The purpose of this study was to test the hypothesis that a progressively faster speed of ascent requires significantly greater peak resultant joint torque (RJT) at major load-bearing joints of the lower limb during the sit-to-stand (STS) transfer. Eight healthy adults performed the STS at slow, natural, and fast speeds. A motion analysis system and two force platforms were employed to record kinetic data, and equations of motion were applied to compute the RJT for the ankle, knee, and hip. The results of the study supported the hypothesis that when the speed of ascent increased progressively, the peak hip flexion, knee extension, and ankle dorsiflexion RJTs increased disproportionately. However, the peak hip extension and ankle plantar flexion RJTs remained relatively constant across the range of the speeds. Implications for clinical practice pertaining to the timing and magnitude of RJT, as well as for interventions that emphasize the adaptive characteristics of movements, are suggested.     

Patients with total knee arthroplasty do not use all of their available range of knee flexion during functional activities

BackgroundRecent research designed to improve outcome from total knee arthroplasty has included focus on strategies that increase the range of post-operative knee flexion. Patients with knee arthroplasty can now expect > 100° of knee flexion following surgery, but it is not clear whether this improved range of motion facilitates outcome or whether patients take advantage of this range when completing daily functional activities. The aim of this study was to investigate the knee flexion angles used during daily functional activities that specifically required high degrees of knee flexion. It was hypothesised that patients with greater range of passive knee flexion would achieve higher degrees of knee flexion during functional activities.MethodsMotion analysis was used to assess the maximum knee flexion of 40 patients with total knee arthroplasty and 40 control participants as they performed maximum flexion squatting and lunging activities.FindingsPatients with knee arthroplasty used between 80.8 and 91.4° of knee flexion to complete these activities, which was 20 to 30% less than that used by the control participants. Patients with greater ranges of passive knee flexion had greater maximum knee flexion during functional activities. However, they used only between 68% and 77% of their full passive range when lunging and squatting.InterpretationThe development of rehabilitation strategies that aim to increase weightbearing knee flexion capacity may be warranted to improve functional performance following total knee arthroplasty.     

Prostheses for persons with lower-limb amputations: an extra joint increases range of motion.

This report describes two cases in which the addition of an extra joint enhanced range of motion and improved function in persons with unilateral lower-limb amputation. Both individuals had significant disability in the workplace and at home before this modification. In the first case, an individual with a hemipelvectomy had inadequate hip-joint flexion for maneuvering during photo shoots. In the second case, the individual's transfemoral prosthesis provided insufficient knee flexion for kneeling and working in tight spaces. In each case, a manual-locking, single-axis knee joint was added adjacent to the joint with the limited range of motion. In both cases, the addition of the second joint provided the increased flexibility needed. The first person's hip-flexion range improved from 125 degrees to 190 degrees, and the second person's knee-flexion range improved from 140 degrees to 170 degrees. In repeated follow-up, both patients remained highly satisfied with the intervention. The addition of an extra joint is an option that should be considered when inadequate range interferes with function.     

A computer simulation of human walking in persons with joint contractures

Joint contractures decrease the patient's ability to walk, but usually other parts of the body compensate the affected joint contractures. When we restore the gait performance in paraplegic patients by means of functional electrical stimulation, however, we cannot expect complications of compensation. A computer simulation was done to clarify how the contractures affect the gait pattern when no complications of compensation were expected. A seven-segment link mechanical model was used for simulation of human walking in the sagittal plane. In turn, using a personal computer stance and swing-leg joint contractures of the ankle, knee, and/or hip were simulated. When stance-leg contracture was simulated, step length became short with increasing hip flexion contracture. The trunk was tilted backward during knee flexion or ankle plantarflexion contracture simulation. When the swing-leg contracture was simulated, step length became short with increasing knee flexion contracture. We found that hip or knee flexion contracture of < or = 15 degrees, or ankle plantarflexion contracture of < 0 degrees was required to maintain positive step length and forward movement of the center of gravity. These findings suggest that 15 degrees of hip and knee flexion contracture, and 0 degrees of ankle plantarflexion contracture are critical when gait restoration is performed by functional electrical stimulation.     

Biomechanical analysis of sit-to-stand movement in normal and obese subjects

OBJECTIVE: Main purpose of this study was to develop a biomechanical model for the analysis of sit-to-stand movement in normal and obese subjects. DESIGN: A biomechanical model describing sit-to-stand was developed using kinetic and kinematic experimental data. Trunk flexion, feet movement, knee and hip joint torques were assumed as sensible indexes to discriminate between normal and obese subjects. BACKGROUND: Sit-to-stand is a functional task that may become difficult for certain patients. The analysis of its execution provides useful biomechanical information on the motor ability of selected subjects. METHODS: Sit-to-stand was recorded using an optoelectronic system and a force platform in 40 obese patients and 10 normal subjects. A biomechanical model was developed using inverse dynamics equations. RESULTS: Kinematic and kinetic indexes evidenced differences in motion strategy between normal and obese subjects. Obese subjects rise from the chair limiting trunk flexion (mean value: 73.1 degrees ) and moving their feet backwards from initial position (mean deviation: 50 mm). Normal subjects, instead, show a higher trunk flexion (mean value: 49.2 degrees, a lower angular value between trunk and the horizontal means increased flexion) and fixed feet position (mean deviation: 5 mm). As for kinetics, obese patients show knee joint torque higher than hip torque (maximum knee torque: 0.75 Nm/kg; maximum hip torque: 0.59 Nm/kg), while normal subjects show opposite behaviour (maximum knee torque: 0.38 Nm/kg; maximum hip torque: 0.98 Nm/kg). RELEVANCE: We found differences in motion strategy between normal and obese subjects performing sit-to-stand movement, which may be used to plan and evaluate rehabilitative treatments.     

Activation of the quadriceps muscle during semisquatting with different hip and knee positions in patients with anterior knee pain.

OBJECTIVE: We measured the surface electromyographic activities of vastus medialis obliquus and vastus lateralis in 16 subjects with patellofemoral joint pain syndrome. DESIGN: Each subject performed bilateral static knee extension exercises at 60% of his or her maximal voluntary effort under different combinations of hip rotation (30 degrees of medial rotation, neutral, 45 degrees of lateral rotation) and knee flexion (20 and 40 degrees) in a standing position. The ratio of surface-integrated electromyographic signals of vastus medialis obliquus over vastus lateralis was calculated for each of the six conditions. Because of significant interaction of hip rotation and knee flexion in the two-way analysis of variance, data were analyzed separately with paired t tests for the effect of knee positions and one-way repeated measures analysis of variance for hip positions. RESULTS: At 20 degrees of knee flexion, there was no significant difference among the three hip positions, whereas at 40 degrees of knee flexion, medial rotation of the hip resulted in significantly higher vastus medialis obliquus over vastus lateralis activity ratio than lateral rotation (P < 0.05). CONCLUSIONS: There was relatively more activation of vastus medialis obliquus than vastus lateralis at 40 degrees of semisquat with the hip medially rotated by 30 degrees. This finding has clinical implications for training the vastus medialis obliquus in patients with patellofemoral joint pain syndrome.     

Intra-operative joint gap kinematics in unicompartmental knee arthroplasty

Background

The use of an offset type tensor for total knee arthroplasty that can be set with patellofemoral joint reduction and femoral component placement enables surgeons to assess soft tissues in the physiological postoperative knee condition, showing different kinematic pattern of soft tissues in varus osteoarthritic knees between cruciate-retaining and posterior-stabilized total knee arthroplasty. However, gap kinematics in unicompartmental knee arthroplasty is unclear.

Methods

Using a newly developed tensor that is designed to assess soft tissue balance throughout the full range of motion with femoral component placement, we assessed the intra-operative joint gap measurements of unicompartmental knee arthroplasties performed at 0, 10, 30, 45, 60, 90, 120 and 135° of flexion in 20 osteoarthritic patients. In addition, the kinematic pattern of unicompartmental knee arthroplasty was compared with those of cruciate-retaining and posterior-stabilized total knee arthroplasty that were calculated as medial compartment gap from the previous series of this study.

Findings

While the joint gap measurements of unicompartmental knee arthroplasties increased from full extension to extension (10° of flexion), these values remained constant throughout the full range of motion. Of note, the gap values of cruciate-retaining total knee arthroplasty were significantly smaller from midrange to deep flexion compared with posterior-stabilized total knee arthroplasty, and furthermore unicompartmental knee arthroplasty showed a significantly smaller gap from extension to midrange flexion compared with cruciate-retaining total knee arthroplasty.

Interpretation

Accordingly, we conclude that the intra-operative joint gap kinematic pattern in unicompartmental knee arthroplasty differs from the pattern in total knee arthroplasty.     

Concurrent validity and reliability of two-dimensional video analysis of hip and knee joint motion during mechanical lifting

Movement patterns used during mechanical lifting are usually assessed subjectively by clinicians as a stoop or squat based on visual estimation of joint motion and position. Two-dimensional (2D) video analysis has the potential to objectively measure joint motion during a mechanical lifting task. This study investigated concurrent validity, intrarater, interrater, and test-retest reliability of 2D video analysis using Dartfish software for the measurement of sagittal plane angles at the hip and knee during mechanical lifting. Fifteen healthy female participants (mean age 27.1?±?7.1 years) were recruited to perform mechanical lifting on 2 separate test days. Concurrent validity was determined by comparing 2D derived hip and knee flexion angles to goniometric measures. Intrarater and interrater reliability of the 2D kinematic procedures was determined by using examiners with varying experience in the use of Dartfish software. Between-day test-retest reliability of hip and knee 2D kinematics during mechanical lifting was assessed. Concurrent validity of 2D angle analysis using Dartfish software was supported by high correlations (Pearson r?≥?0.95) and nonsignificant differences between 2D and goniometric measures of sagittal plane hip and knee motion. Both intrarater and interrater reliability values of hip and knee flexion angles were excellent (ICC?≥?0.91). ICCs for test-retest reliability were 0.79 and 0.91 for hip and knee flexion, respectively. These findings and the ease of data capture using this system provide support for the clinical utility of 2D video analysis to provide objective measures of movement patterns at the hip and knee during a dynamic functional task.     

A videofluoroscopy method for optical distortion correction and measurement of knee-joint kinematics

Image distortion in video and image intensifier X-ray systems requires appropriate distortion correction methods to obtain accurate biomechanical quantitative measurements for joint kinematics applications. This paper presents an algorithm for coordinate reconstruction and distortion correction using a modified polynomial method. This algorithm was used for the measurement of patellar tendon moment arm, tibial plateau-tibial axis angle and patellar tendon-tibial axis angle during knee extension using videofluoroscopy in vivo. These parameters allow the determination of a two-dimensional biomechanical model of the knee for the measurement of muscle and joint forces during dynamic activities. Five males without knee joint injury history participated in the study. The mean measurement error obtained using an image intensifier-video system was 0.246 +/- 0.111 mm over a 180-mm x 180-mm field of view. The mean maximum patellar tendon moment arm was 39.87 mm at 44.9 degrees of knee flexion. The patellar tendon-tibial plateau angle was 112.9 degrees at full extension and decreased linearly to 87.6 degrees at 90 degrees of knee flexion. The mean angle between the tibial plateau and the tibial long axis was 84.8 degrees. Applications of the method include motion analysis using video and X-ray fluoroscopy systems with non-linear distortion problems. RELEVANCE: Accurate measurement of anatomical parameters from videofluoroscopy systems is important for the determination of joint biomechanical models and measurement of muscular and joint forces.     

Lumbofemoral rhythm during active hip flexion in standing in healthy older adults

The 2D PEAK Motus motion analysis system was used to measure the sagittal lumbofemoral rhythm during active hip (knee) flexion in standing in 34 healthy older adults whose movement may be influenced by age-related changes in the neuromusculoskeletal system. When the thigh was raised, the lumbar spine moved concurrently with the hip joint throughout the movement. Approximately 5° of initial hip flexion occurred before 1° of lumbar flexion. Overall, the lumbar spine contributed 26.6% (29.3°) of the total thigh movement (pelvis + hip joint) during the upward (110.2°) movement phase. Compared to children and young adults, older adults demonstrated some age-related differences in sagittal lumbofemoral rhythm, including decreased hip flexion and a large variation in the hip-to-lumbar movement ratio. Clinicians and exercise instructors need to be aware of the concurrent movement interaction between the hip joint and lumbar spine when measuring hip flexion range or when instructing abdominal, hip, or lumbar exercises. The potential influence of limited range of motion of either hip or lumbar component on the movement should also be addressed.     

Extent and direction of joint motion limitation after prolonged immobility: an experimental study in the rat

OBJECTIVES: To test the hypotheses that contractures progress at different rates in relation to the time after immobilization, that immobilization in flexion leads to loss of extension range of motion, and that joints of sham-operated animals are better controls than the contralateral joint of experimental animals. STUDY DESIGN: Experimental, controlled study in which 40 adult rats had one knee joint immobilized at 135 degrees of flexion for up to 32 weeks and 20 animals underwent a sham procedure. At intervals of 2, 4, 8, 16, and 32 weeks, 8 experimental and 4 sham-operated animals were killed and their knee motion measured in flexion and extension. RESULTS: In the experimental group, the range of motion decreased in the first 16 weeks of immobility at an average rate of 3.8 degrees per week (p<.0001) to reach 61.1 degrees of restriction. A plateau was then observed from which the contracture did not progress further. The loss in range of motion occurred in extension, not in flexion. CONCLUSION: This study defined an acute stage of contractures starting at the onset of immobility and lasting 16 weeks, during which the range of motion was progressively restricted, and a chronic stage during which no additional limitation was detected. The loss in motion was attributed to posterior knee structures not under tension during immobilization in flexion. Contrary to the hypothesis, the contralateral joint was validated as a control choice for range-of-motion experiments.     

A comparison of two stretching programs for hamstring muscles: A randomized controlled assessor-blinded study

Most parameters regarding hamstring flexibility training programs have been investigated; however, the joint (i.e. hip or knee) on which the stretching should preferentially be focused needs to be further explored. This randomized controlled assessor-blinded study aimed to investigate the influence of this parameter. We randomly assigned 111 asymptomatic participants with tight hamstring muscles in three groups: a control group and two groups following a different home-based 8-week (five 10-minute sessions per week) hamstring stretching program (i.e. stretching performed by flexing the hip while keeping the knee extended [SH] or by first flexing the hip with a flexed knee and then extending the knee [SK]). Range of motion (ROM) of hip flexion and knee extension were measured before and after the stretching program by means of the straight leg raising test and the passive knee extension angle test, respectively. Eighty-nine participants completed the study. A significant increase in ROM was observed at post-test. Analyses showed significant group-by-time interactions for changes regarding all outcomes. Whereas the increase in hip flexion and knee extension ROM was higher in the stretching groups than in the CG (especially for the SH group p < 0.05), no differences between the two stretching groups were observed (p > 0.05). In conclusion, the fact that both stretching programs resulted in similar results suggests no influence of the joint at which the stretching is focused upon, as assessed by the straight leg raising and knee extension angle tests.