Juvenile idiopathic arthritis (JIA) patients (
Juvenile idiopathic arthritis (JIA) in children and adolescents is a chronic autoinflammatory affection which might occur in any joint [
A method to analyze the human gait is the 3d-gait analysis. At the German Center for Pediatric and Adolescent Rheumatology Garmisch-Partenkirchen, this technique is performed in JIA patients with multiple affected joints in the lower extremities to quantify kinematics and kinetics to individualize and optimize the physio- and sports therapy.
Physical activities are increasingly considered as an important part of treatment for JIA patients. Moreover inactivity is expected as a major factor of substantial negative effects for the musculoskeletal system, the whole body- composition, and the physical ability of JIA patients. The aim of therapy is to retain or regain an adequate level of activity in order to counteract the loss of coordination and fitness in spite of the disease activity.
In therapy of JIA, prevention of joint dysfunction and reeducation of physiological movements are important issues which might be supported by sport activities.
The aim of this study was to compare the gait of JIA patients with normal gait and further to quantify malpositions in the lower extremities and joint restrictions during walking condition. These data may lead to recommendations about sport activities.
The study is based on a retrospective analysis of JIA patients admitted in the German Center for Pediatric and Adolescent Rheumatology, Garmisch-Partenkirchen between August 2006 and November 2009. The 3d gait analysis is a part of the routine procedures used to quantify movement restrictions to individualize physiotherapy. Written consent was delivered by the participants or parents (legal guardians) for the anonymous use of these data for scientific purpose.
The patient group (JIA-P) (
Comparison of our measured standard values with results from the literature showed only minor deviations [
Gait analysis is performed in a 9 m long and 3 m wide laboratory which is equipped with a 3d-motion analysis system including six infrared cameras (120 Hz) (Vicon, MX3) and one 3d ground reaction force plate (1080 Hz) (AMTI). The participants were marked in accordance to the Plug-in-Gait Model for the lower extremities [
Placement of the Plug-in-Gait Model.
As most of our JIA-patients had walking disabilities, we have asked the participants to select a walking speed which was pleasant for them. Each subject completed at least two attempts in order to get accustomed to the measuring situation before the analysis started. For the kinematic evaluation twelve left and right gait cycles were used. The kinetic data consist of three left and right steps of each individual.
The gait was scaled and normalized in separated gait cycles, consisting of a stance and a swing phase of one limb. A gait cycle starts with the initial contact and ends with the next initial contact of the same leg (Figure
Normal gait cycle with approximated event timings (modified to Perry [
The maximum peak values of kinetic data were calculated in the ankle dorsal flexion moment and in the power that is generated in the ankle (Figure
Statistical analyses for comparison were performed using the
Kinematic and spatio-temporal data included all participants of JIA-P and CG. In five individuals (1 JIA-P, 4 CG) ground reaction force data were not available due to invalid contact or technical difficulties. Thus inverse dynamic calculations were possible only in 35 patients and 16 controls. Subsequently the account will focus predominantly on statistically significant differences, and conspicuous results of the joint assessment will be presented.
Comparison of spatio-temporal parameters showed statistically significant differences in the self-chosen walking speed (
Results of spatio-temporal parameters (
Control group ( | mean (SD) | JIA-Patients ( | mean (SD) | |||
---|---|---|---|---|---|---|
Foot Off | [%] | 59.9 | 1.7 | 61.1 | 2.3 | .049 |
Step Length | [m] | .63 | .05 | .53 | .08 | .000 |
Dimensionless Step Length | .78 | .04 | .69 | .12 | .000 | |
Walking Speed | [m/s] | 1.32 | .08 | 1.06 | .17 | .000 |
Dimensionless Walking Speed | .47 | .03 | .39 | .07 | .000 | |
Step Width | [m] | .09 | .02 | .12 | .04 | .010 |
Patients showed a stronger anterior tilting pelvis than controls (
Kinematic parameters in pelvis, knee, and ankle Joint (
Control group ( | Mean (SD) | JIA-Patients ( | Mean (SD) | |||
---|---|---|---|---|---|---|
Pelvic Tilt-Average | [ | 10,8 | 3,9 | 14,2 | 5,9 | ,027 |
Pelvic Obliquity (ROM ( | [ | 3,6 | 1,2 | 2,7 | 1,5 | ,022 |
Pelvic Obliquity ROM | [ | 11,2 | 5,1 | 12,4 | 5,4 | NS |
Hip Flex/Ext-max. extension | [ | 5,8 | 5,4 | 8,3 | ,002 | |
Hip Flex/Ext-max. flexion | [ | 38,2 | 4,0 | 39,6 | 7,4 | NS |
Hip Flex/Ext-ROM | [ | 44,0 | 3,3 | 38,8 | 5,9 | ,001 |
Hip Abd/Add-max.Abd | [ | 6,0 | 2,8 | 4,2 | 2,0 | ,009 |
Hip Abd/Add-max.Add | [ | 7,8 | 2,6 | 7,2 | 3,0 | NS |
Hip Abd/Add-ROM | [ | 13,8 | 3,5 | 11,4 | 3,4 | ,019 |
Knee Flex/Ext- | [ | 12,7 | 3,2 | 12,4 | 4,8 | NS |
Knee Flex/Ext- | [ | 24,6 | 4,3 | 23,1 | 4,9 | NS |
Knee Flex/Ext- | [ | 8,8 | 4,4 | 13,4 | 4,9 | ,001 |
Knee Flex/Ext- | [ | 65,5 | 3,0 | 59,7 | 6,2 | ,000 |
Knee Flex/Ext (ROM ( | [ | 12,0 | 2,3 | 10,7 | 3,9 | NS |
Knee Flex/Ext (ROM ( | [ | 15,8 | 3,2 | 9,7 | 4,5 | ,000 |
Knee Flex/Ext (ROM ( | [ | 56,7 | 3,8 | 46,4 | 8,3 | ,000 |
Ankle Dorsi/Plan- | [ | 4,2 | 2,6 | 2,6 | 3,9 | NS |
Ankle Dorsi/Plan- | [ | ,6 | 2,8 | 3,2 | NS | |
Ankle Dorsi/Plan- | [ | 17,9 | 2,8 | 18,9 | 3,2 | NS |
Ankle Dorsi/Plan- | [ | 4,5 | 10,0 | ,010 | ||
Ankle Dorsi/Plan-(ROM ( | [ | 3,6 | 1,3 | 3,1 | 1,8 | NS |
Ankle Dorsi/Plan-(ROM ( | [ | 17,4 | 3,0 | 19,4 | 4,0 | NS |
Ankle Dorsi/Plan-(ROM ( | [ | 31,0 | 4,9 | 25,6 | 7,9 | ,008 |
Plantar Angle-Initial Contact | [ | 2,6 | 4,8 | ,012 | ||
Plantar Angle-max (swing phase) | [ | 4,1 | 11,7 | ,001 | ||
Foot-Flat (± | [%] | 23,7 | 4,8 | 27,7 | 8,0 | ,045 |
Comparison of angle progression in the pelvic tilt (a) and obliquity (b). CG (arithmetic mean & SD (- - -)); JIA-P (arithmetic mean and SD (—)).
The maximum ROM during hip flexion and extension during stance phase appeared clearly different (
Results of gait analysis of CG (arithmetic mean & SD (- - -)) and JIA-P (arithmetic mean & SD (—)) in hip (a) flexion/extension, (b) abduction/adduction, and knee joint, (c) flexion/extension.
Results of CG (arithmetic mean & SD (- - -)) and JIA-P (arithmetic mean & SD (—)) in time normalized (%) gait cycle in ankle and plantar angle. (a) In ankle (dorsal/plantar flexion),
It shows kinetic results of CG (arithmetic mean & SD (- - -)) and JIA-P (arithmetic mean & SD (—)) in time normalized (%) gait cycle of the ankle. (a) Ankle moment (dorsal/plantar flexion). (b) Ankle power.
Kinetic results of CG (arithmetic mean & SD (- - -)) and JIA-P (arithmetic mean & SD (—)) in time normalized (%) gait cycle of ground reaction forces (GRF). (a) In the vertical GRF (
From the initial contact (
The dorsal flexion of the ankle joint movement throughout the stance phase (
The plantar angle (Figure
The maximum peak of kinetic ankle dorsal flexion moment showed smaller values in JIA-P compared to the CG (
The comparison of the three turning points
Kinetic parameters of the Ground Reaction Force (GRF) in vertical plane (
Control group ( | Mean (SD) | JIA-Patients ( | Mean (SD) | |||
---|---|---|---|---|---|---|
GRF( | [% BWT] | 107,0 | 15,5 | 110,6 | 9,7 | NS |
GRF( | [% BWT] | 71,7 | 9,8 | 77,4 | 7,2 | ,025 |
GRF( | [% BWT] | 111,8 | 16,4 | 106,9 | 6,9 | NS |
GRF( | [% BWT] | 17,2 | 3,7 | 15,8 | 3,6 | NS |
GRF( | [% BWT] | 3,2 | 4,3 | ,001 | ||
Ankle (max-Dorsi-moment) | [Nm/kg(BWt)] | 1,5 | ,2 | 1,2 | ,2 | ,001 |
Ankle (max-Power generation) | [W/kg(BWt)] | 4,5 | ,9 | 3,0 | 1,2 | ,000 |
Comparison of gait parameters between JIA Patients with a polyarticular pattern of joint involvement of the lower extremities and healthy young individuals showed statistically significant differences. First the decreased walking speed of patients may result from pain, movement restrictions, and compensatory movements but as well from insufficient practice. Decrease of the self-selected walking speed in JIA patients has been observed in other studies as well. There is a statistically significant negative correlation with pain and progressive movement speed in children with JIA [
The measured hip extension restriction during single stance phase in JIA-P together with the smaller ROM in the hip (flexion/extension) may be responsible for the shorter step length and slower walking speed [
Götz-Neumann [
The decreased maximum knee flexion in swing phase measured in JIA-P may be interpreted as a functionally reduced locomotion and thus be a symptom of knee pain or reduced forward motion of the thigh which is in accordance with the data reported by others [
The knee flexion during loading response was found to be in normal ranges and is therefore better than expected from the data of a smaller patient group of JIA patients with minor amount of affected joints that we published before [
The ankle joint of JIA-P showed an increased (not significant) dorsal flexion during stance phase. This must be interpreted together with the observation of the extended time duration while the foot stands flat on the ground and the strongly decreased plantar flexion during push off. The timing of foot off appears in JIA-P 1.2% of a gait cycle later than in CG. Although the toe off in our investigation groups appeared within the normal range of a gait cycle, the previous facts suggest a more passive and decelerated roll off behavior in patients. These results are supported by the decreased plantar flexion in JIA-P during gait which was confirmed in 29 patients by clinical assessment.
The special character of the sagittal joint movement in the gait of JIA-P with hyperflexion in hip and knee joints and reduced plantar flexion in the ankle may be described as a crouch-like gait. This can be characterized as typical gait for patients with polyarticular JIA.
The decreased ROM in the contra lateral drop of the pelvis of JIA-P during loading response might be a sign for a compensatory movement. We and others relate this to hip pain [
Kinetic differences in the lower peaks of ankle joint moments and in ankle power of JIA-P add to a more passive and less dynamic push off compared to controls. This effect also results in the reduced loading of the horizontal ground reaction force (
Although the JIA-P represent a homogeneous sample with similar joint manifestations, standard deviations were increased. This suggests that the disease creates very individual patterns of joint disturbances.
The results of the 3d-gait analysis gave new and affirmative arguments that help to recommend sport therapy. Additionally the expertise in pathophysiology and treatment of JIA-P with polyarticular joint pattern was also taken into account for the following suggestions [
The 3d-gait analysis showed that the patient group suffered from malpositions that can be ascribed to movement restrictions or relieving postures which again can result in further movement restrictions. The main differences compared to controls lay in reduced hip extension, reduced knee extension, and reduced plantar flexion with a passive and decelerated push off of the ankle. Joint restriction goes along with a hypertonic flexor muscle loop and a hypotonic extensor muscle loop. Another study found that the exercise capacity is significantly decreased in a large amount of JIA-P group [
Pain and inflammation reduce the muscle strength for plantar flexion, knee extension and weaken the gluteal muscles [
Continuous sports activity will automatically normalize endurance. So this important part of physical ability can be improved indirectly.
Based on the underlying passivity of the ankle joint and the therefore decelerated progression, as well as on the crouch-like gait, the ability to react on unforeseen situations may be considered to be one of the major limiting factors in JIA-P. In this case, functional joint flexibility is as important as lower limb strength and the ability to coordinate it.
As JIA tends to run with phases of relapses and remission, we suggest integrating a preventive mobility workout (PMW) for the entire body very close to the present state of an individual patient. A short daily workout including mobility and strengthening exercises could lead to a better functional outcome of the lower limb. This must be analyzed by a longitudinal intervention study.
In general sport activities with a hard and irregular underground like alpine skiing may cause imbalanced movements which result in high strains on the muscular skeletal system. This means a large training stimulus but with higher risk of injury and a possible worse joint prognoses when starting before remission [
Bicycle riding is a smooth motion with low impact and is regarded as an optimum activity for JIA patients. However, the fixed sitting position may produce movement restrictions especially concerning hip extension. Therefore an individualized stretching program should be included also in a gentle sport like bicycle riding.
If arthritis is located at the lower extremities, optimized training programs should take in exercises with smooth motions and low impact. Motion patterns in joints should develop a large ROM that works towards the extension of knee and hip joints. Examples are the diagonal technique of classic style cross-country skiing, swimming (crawl), or Nordic Walking.
The results indicate the wide range of disturbances in the mobility of the lower extremities in patients suffering from JIA. 3d-gait analysis has demonstrated to be a powerful tool in quantification of movement abnormalities in patients with JIA. Nearly one third of JIA patients reaching adulthood suffer from limitations in their ability to move [
The authors wish to thank the German Foundation