Tendon release reduced joint stiffness with unaltered leg stiffness during gait in spastic diplegic cerebral palsy.

Biomechanical deviations at individual joints are often identified by gait analysis of patients with cerebral palsy (CP). Analysis of the control of joint and leg stiffness of the locomotor system during gait in children with spastic diplegic CP has been used to reveal their control strategy, but the differences between before and after surgery remain unknown. The current study aimed to bridge the gap by comparing the leg stiffness-both skeletal and muscular components-and associated joint stiffness during gait in 12 healthy controls and 12 children with spastic diplegic CP before and after tendon release surgery (TRS). Each subject walked at a self-selected pace on a 10-meter walkway while their kinematic and forceplate data were measured to calculate the stiffness-related variables during loading response, mid-stance, terminal stance, and pre-swing. The CP group altered the stiffness of the lower limb joints and decreased the demand on the muscular components while maintaining an unaltered leg stiffness during stance phase after the TRS. The TRS surgery improved the joint and leg stiffness control during gait, although residual deficits and associated deviations still remained. It is suggested that the stiffness-related variables be included in future clinical gait analysis for a more complete assessment of gait in children with CP.

Postural adjustments in adolescent idiopathic thoracic scoliosis during walking.

INTRODUCTION: Adolescent idiopathic scoliosis (AIS) is the most common type of three-dimensional spinal deformity. Identifying the postural adjustments or changes for different phases and events is needed for developing programs to improve the AIS gait, but such information has been limited. The current study aimed to fill the gap via three-dimensional motion analysis of quiet standing and level walking in patients with severe thoracic AIS. MATERIALS AND METHODS: Sixteen female adolescents with AIS (Lenke 1 or 2, age: 14.9 ±â€¯1.7 years, height: 154.7 ±â€¯5.0 cm, mass: 41.7 ±â€¯7.2 kg) and sixteen sex-, age- and BMI-matched healthy controls (age: 14.8 ±â€¯2.7 years, height: 154.9 ±â€¯5.6 cm, mass: 44.7 ±â€¯6.3 kg) participated in the current study with informed written consent. The kinematic and kinetic changes between the trunk, pelvis, and lower limb segments, and at the lumbosacral level at different gait events were measured during quiet standing and level walking. RESULTS: The homogeneity of the current patient group helped reduce the effects of the level and severity of spinal deformity on inter-subject variability that has been associated with controversies over reported gait variables in AIS. The current results support the hypothesis that postural adjustments involving the trunk, pelvis and lower limb segments were needed in severe thoracic AIS during both quiet standing and level walking, and differed between concave and convex sides at different key gait events during level walking. CONCLUSIONS: Although scoliotic spinal deformity occurred mainly in the frontal plane, postural adjustments in all three planes were present at key events during level walking with associated joint loading changes in patients with severe thoracic AIS. Monitoring of such adjustments and the associated joint kinetic changes will be helpful for assessing the disease and treatment outcomes.

Effects of gait speed on the body's center of mass motion relative to the center of pressure during over-ground walking.

Preferred walking speed (PWS) reflects the integrated performance of the relevant physiological sub-systems, including energy expenditure. It remains unclear whether the PWS during over-ground walking is chosen to optimize one's balance control because studies on the effects of speed on the body's balance control have been limited. The current study aimed to bridge the gap by quantifying the effects of the walking speed on the body's center of mass (COM) motion relative to the center of pressure (COP) in terms of the changes and directness of the COM-COP inclination angle (IA) and its rate of change (RCIA). Data of the COM and COP were measured from fifteen young healthy males at three walking speeds including PWS using a motion capture system. The values of IAs and RCIAs at key gait events and their average values over gait phases were compared between speeds using one-way repeated measures ANOVA. With increasing walking speed, most of the IA and RCIA related variables were significantly increased (p<0.05) but not for those of the frontal IA. Significant quadratic trends (p<0.05) with highest directness at PWS were found in IA during single-limb support, and in RCIA during single-limb and double-limb support. The results suggest that walking at PWS corresponded to the COM-COP control maximizing the directness of the RCIAs over the gait cycle, a compromise between the effects of walking speed and the speed of weight transfer. The data of IA and RCIA at PWS may be used in future assessment of balance control ability in people with different levels of balance impairments.

Kinematic strategies for obstacle-crossing in patients with isolated posterior cruciate ligament deficiency.

The posterior cruciate ligament (PCL) plays an important role in the structural stability and sensory feedback at the knee. Altered structural and proprioceptive function at the PCL-deficient knee may affect the joint motions and the end-point control during functional activities. The current study identified the effects of unilateral PCL deficiency (PCLD) on the end-point control and joint kinematics of the lower limbs during obstacle-crossing. Eighteen patients with unilateral PCLD and eighteen healthy controls were each asked to walk and cross obstacles of heights of 10%, 20% and 30% of their leg lengths, with the affected and the unaffected limb leading, while their kinematic data were measured. Patients with PCLD were found to cross obstacles with significantly increased toe-clearance (p<0.01), increased trailing toe-obstacle distance (p<0.05) and reduced crossing speed (p<0.01) when compared to the controls. Similar end-point control was observed in the PCLD group whether leading with the affected or unaffected limb, which appears to be as a result of bilateral kinematic accommodation to reduce the risk of tripping. To achieve similar toe-clearances, crossing strategies with the unaffected limb leading involved angular changes at more joints than those with the affected limb leading. The PCLD group appeared to adopt a conservative strategy to reduce the risk of tripping over the obstacle during obstacle-crossing, using different joint kinematic changes depending on whether the affected or unaffected limb was leading. It is suggested that monitoring of the kinematic strategies adopted by patients with PCLD during obstacle-crossing may be needed in future rehabilitation programs with the aim of reducing tripping risks during obstacle-crossing.

Loading rates during walking in adolescents with type II osteonecrosis secondary to pelvic osteotomy.

Although Pemberton osteotomy has shown a high success rate even in older children, the occurrence of osteonecrosis (ON) remains one of the most severe complications, leading to premature osteoarthritis. Patients with type II ON are characterized by a valgus deformity of the proximal femur with altered musculoskeletal conditions, affecting the ability to attenuate or sustain the impulsive loading from the ground reaction force. It remains unclear whether these conditions also predispose these patients to harmful impulsive loadings. This study aimed to bridge the gap by measuring the loading rates in the lower limbs during level walking in adolescents who were treated during their infancy for unilateral developmental dysplasia of the hip by a pelvic osteotomy, with or without having developed type II ON. Patients with type II ON were found to display increased loading rates, not only at both the affected and unaffected hip, but also at other joints of the affected limb during level walking when compared to patients without ON changes (p < 0.05). These results suggest that patients with type II ON may be at a higher risk of developing premature hip osteoarthritis that is closely related to abnormal loading rates during gait. It is suggested that regular monitoring of joint loading rates in patients with type II ON is necessary for early identification of damaging loadings, and that early intervention aimed at reducing these loadings should be considered. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2199-2206, 2016.

Leg and Joint Stiffness in Children with Spastic Diplegic Cerebral Palsy during Level Walking.

Individual joint deviations are often identified in the analysis of cerebral palsy (CP) gait. However, knowledge is limited as to how these deviations affect the control of the locomotor system as a whole when striving to meet the demands of walking. The current study aimed to bridge the gap by describing the control of the locomotor system in children with diplegic CP in terms of their leg stiffness, both skeletal and muscular components, and associated joint stiffness during gait. Twelve children with spastic diplegia CP and 12 healthy controls walked at a self-selected pace in a gait laboratory while their kinematic and forceplate data were measured and analyzed during loading response, mid-stance, terminal stance and pre-swing. For calculating the leg stiffness, each of the lower limbs was modeled as a non-linear spring, connecting the hip joint center and the corresponding center of pressure, with varying stiffness that was calculated as the slope (gradient) of the axial force vs. the deformation curve. The leg stiffness was further decomposed into skeletal and muscular components considering the alignment of the lower limb. The ankle, knee and hip of the limb were modeled as revolute joints with torsional springs whose stiffness was calculated as the slope of the moment vs. the angle curve of the joint. Independent t-tests were performed for between-group comparisons of all the variables. The CP group significantly decreased the leg stiffness but increased the joint stiffness during stance phase, except during terminal stance where the leg stiffness was increased. They appeared to rely more on muscular contributions to achieve the required leg stiffness, increasing the muscular demands in maintaining the body posture against collapse. Leg stiffness plays a critical role in modulating the kinematics and kinetics of the locomotor system during gait in the diplegic CP.

Control of body's center of mass motion relative to center of pressure during uphill walking in the elderly.

Uphill walking places more challenges on the locomotor system than level walking does when the two limbs work together to ensure the stability and continuous progression of the body over the base of support. With age-related degeneration older people may have more difficulty in maintaining balance during uphill walking, and may thus experience an increased risk of falling. The current study aimed to investigate using gait analysis techniques to determine the effects of age and slope angles on the control of the COM relative to the COP in terms of their inclination angles (IA) and the rate of change of IA (RCIA) during uphill walking. The elderly were found to show IAs similar to those of the young, but with reduced self-selected walking speed and RCIAs (P<0.05). After adjusting for walking speed differences, the elderly showed significantly greater excursions of IA in the sagittal plane (P<0.05) and increased RCIA at heel-strike and during single limb support (SLS) and double limb support (DLS) in the sagittal plane (P<0.05), and increased RCIA at heel-strike in the frontal plane (P<0.05). The RCIAs were significantly reduced with increasing slope angles (P<0.05). The current results show that the elderly adopted a control strategy different from the young during uphill walking, and that the IA and RCIA during walking provide a sensitive measure to differentiate individuals with different balance control abilities. The current results and findings may serve as baseline data for future clinical and ergonomic applications.

A dental implant-based registration method for measuring mandibular kinematics using cone beam computed tomography-based fluoroscopy.

PURPOSE: This study aimed to develop and evaluate experimentally an implant-based registration method for measuring three-dimensional (3D) kinematics of the mandible and dental implants in the mandible based on dental cone beam computed tomography (CBCT), modified to include fluoroscopic function. MATERIALS AND METHODS: The proposed implant-based registration method was based on the registration of CBCT data of implants/bones with single-plane fluoroscopy images. Seven registration conditions that included one to three implants were evaluated experimentally for their performance in a cadaveric porcine headmodel. RESULTS: The implant-based registration method was shown to have measurement errors (SD) of less than -0.2 (0.3) mm, 1.1 (2.2) mm, and 0.7 degrees (1.3 degrees) for the in-plane translation, out-of-plane translation, and all angular components, respectively, regardless of the number of implants used. The corresponding errors were reduced to less than -0.1 (0.1) mm, -0.3 (1.7) mm, and 0.5 degree (0.4 degree) when three implants were used. CONCLUSION: An implant-based registration method was developed to measure the 3D kinematics of the mandible/implants. With its high accuracy and reliability, the new method will be useful for measuring the 3D motion of the bones/implants for relevant applications.

Redistribution of intra- and inter-limb support moments during downhill walking on different slopes.

Downhill walking presents a greater risk of falling as a result of slipping or loss of balance in comparison with level walking. The current study aimed to investigate the effects of inclination angles on the intra-limb (inter-joint) and inter-limb sharing of the body support during downhill walking for a better understanding of the associated control strategy. Fifteen young male adults (age: 32.6±5.2 years, height: 168.9±5.5cm, mass: 68.4±8.7kg) performed level and downhill walking while their kinematic and kinetic data were measured for calculating joint moments and total support moments of the lower limbs using inverse dynamics analysis. The peak total support moments of both the leading and trailing limbs increased with increasing inclination angles (p<0.05) with different sharing patterns among individual joints. Being the major contributor to the peak total support moment during early single-limb support, the contribution of the knee remained unaltered (p>0.05), but the contributions of the hip increased with reduced contributions from the ankle (p<0.05). For the increased peak total support moment during late single-limb support, the intra-limb sharing changed from a major ankle contribution to a major knee contribution strategy. The hip contribution was also increased (p<0.05) but the hip flexor moment remained unaltered (p>0.05). During double-limb support, the main contributor to the whole body support changed from the trailing limb to the leading limb with increasing inclination angles (p<0.05).

Influence of inclination angles on intra- and inter-limb load-sharing during uphill walking.

Uphill walking is an inevitable part of daily living, placing more challenges on the locomotor system with greater risk of falls than level walking does. The current study aimed to investigate the effects of inclination angles on the inter-joint and inter-limb load-sharing during uphill walking in terms of total support moment and contributions of individual joint moments to the total support moment. Fifteen young adults walked up walkways with 0°, 5°, 10° and 15° of slope while kinematic and kinetic data were collected and analyzed. With increasing inclination angles, the first peak of the total support moment was increased with unaltered individual joint contributions, suggesting an unaltered inter-joint control pattern in the leading limb to meet the increased demands. The second peak of the total support moment remained unchanged with increasing inclination angles primarily through a compensatory redistribution of the hip and knee moments. During DLS, the leading limb shared the majority of the whole body support moments. The current results reveal basic intra- and inter-limb load-sharing patterns of uphill walking, which will be helpful for a better understanding of the control strategies adopted and for subsequent clinical applications.

Effects of bilateral medial knee osteoarthritis on intra- and inter-limb contributions to body support during gait.

Patients with knee OA show altered gait patterns, affecting their quality of living. The current study aimed to quantify the effects of bilateral knee OA on the intra-limb and inter-limb sharing of the support of the body during gait. Fifteen patients with mild, 15 with severe bilateral knee OA, and 15 healthy controls walked along a walkway while the kinematic and kinetic data were measured. Compared with the controls, the patients significantly reduced their knee extensor moments and the corresponding contributions to the total support moment in the sagittal plane (p<0.05). For compensation, the mild OA group significantly increased the hip extensor moments (p<0.05) to maintain close-to-normal support and a more symmetrical inter-limb load-sharing during double-limb support. The severe OA group involved compensatory actions of both the ankle and hip, but did not succeed in maintaining a normal sagittal total support moment during late stance, nor a symmetrical inter-limb load-sharing during double-limb support. In the frontal plane, the knee abductor moments and the corresponding contributions to the total support moment were not affected by the changes in the other joints, regardless of the severity of the disease. The observed compensatory changes suggest that strengthening of weak hip muscles is essential for body support during gait in patients with knee OA, but that training of weak ankle muscles may also be needed for patients with severe knee OA.

Clinical outcomes following sublaminar-trimming laminoplasty for extensive lumbar canal stenosis.

PURPOSE: Current surgical approaches for treatment of lumbar canal stenosis are often associated with relatively high rates of reoperation and recurrent stenosis. We have developed a new approach for treatment of this condition: sublaminar-trimming laminoplasty. To describe the surgical approach of sublaminar-trimming laminoplasty and to assess associated outcomes. METHODS: Patients with extensive lumbar canal stenosis who received sublaminar-trimming laminoplasty from 2006 to 2008 were considered for inclusion in the study. The surgery comprised aspects of laminotomy and laminectomy. The following were assessed before surgery and 3 years after surgery: leg and back pain by visual analog scale (VAS), extent of disability by Oswestry Disability Index (ODI), severity of back pain by Japanese Orthopedic Association Score for Back Pain (JOA), walking tolerance, and leg numbness. Complications were noted. RESULTS: A total of 49 patients were included in the study (mean age 65.6 ± 10.6 years). VAS leg and back pain, ODI, and JOA scores significantly changed from before surgery to 3 years after surgery (P < 0.001). Mean changes (95 % confidence interval) were -6.2 (-6.7, -5.7), -4.3 (-4.8, -3.8), -21.4 (-23.4, -19.5), and 13.4 (12.1, 14.7) for leg pain, back pain, ODI, and JOA scores, respectively. Patients experienced significant improvements in walking tolerance and leg numbness (P < 0.001). There were no instances of recurrent stenosis or postoperative spinal instability. Complications included intraoperative dural tear (n = 2), postoperative urinary tract infection (n = 2), and inadequate decompression and junctional stenosis during follow-up (both n = 1). CONCLUSION: Sublaminar-trimming laminoplasty shows promise as an effective treatment for extensive lumbar canal stenosis.

Symmetrical kinematic changes in highly functioning older patients post-stroke during obstacle-crossing.

With the advances in stroke care, the number of high-functioning patients after stroke is increasing. However, existing clinical tools may not be sensitive enough to identify the residual deficits in these patients. The current study aimed to investigate the control of the pelvis, and the joints and end-point of the lower limbs in high-functioning older patients post-stroke during obstacle-crossing using motion analysis techniques. Twenty-four high-functioning older patients following unilateral stroke and fifteen healthy controls walked and crossed obstacles of three different heights. End-point variables (leading toe-clearance and trailing toe-obstacle distance) and crossing pelvic and joint angles were obtained for both limbs during leading limb crossing. Whether leading with the contralesional or ipsilesional limb, the stroke group exhibited significantly different joint kinematics from the controls mainly in the frontal and transverse planes, with greater leading toe-clearance, trailing toe-obstacle distance, and posterior pelvic tilt. None of the end-point and joint variables were significantly different between limbs. High-functioning patients post-stroke appeared to have acquired a specific symmetric kinematic strategy with increased leading toe-clearance during obstacle-crossing, most likely in order to prevent tripping. This symmetric strategy, possibly a consequence of brain reorganization, may help in performing functional activities during which symmetric performance between the contralesional and ipsilesional sides is required. Obstacle-crossing training with both limbs leading alternately may be helpful for the development of this symmetric strategy. It is suggested that computerized motion analysis of obstacle-crossing can be a sensitive assessment tool for distinguishing the motor performance between normal and high-functioning patients post-stroke.