High-demand motor tasks are more sensitive to detect persisting alterations in muscle activation following total knee replacement.

Knee osteoarthritis is one of the most frequent indications for total knee replacement (TKR). Unfortunately, many patients still have difficulties during daily life activities after TKR. As the underlying causes of these difficulties are still not fully understood, especially with regard to the role of aberrant muscle activation profiles, the purpose of this study was to examine to what extent muscle activation patterns return to normal after TKR. Furthermore, we aimed to further discuss remaining differences by linking them to pre- and post-operative measurements of the knee and hip kinetics and kinematics during multiple functional motor tasks. Therefore, muscle activity, kinetics and kinematics of knee and hip were measured and analyzed in seven patients during a number of functional tasks by using electromyography and three-dimensional motion analysis. Measurements were performed one week before and one year after surgery. Results were compared to seven matched healthy controls. The analyzed functional tasks included walking at self-selected speed, walking followed by a crossover and a sidestep turn, step descent and ascent. This study suggested that, while muscle activation profiles in patients one year after TKR did return to normal during walking, this was not the case during more demanding motor tasks. These findings may have direct implications for the design of future rehabilitation programs in order to result in faster recovery and ultimately more functional patients after TKR.

Three-dimensional knee kinematics by conventional gait analysis for eleven motor tasks of daily living: typical patterns and repeatability.

The availability of detailed knee kinematic data during various activities can facilitate clinical studies of this joint. To describe in detail normal knee joint rotations in all three anatomical planes, 25 healthy subjects (aged 22-49 years) performed eleven motor tasks, including walking, step ascent and descent, each with and without sidestep or crossover turns, chair rise, mild and deep squats, and forward lunge. Kinematic data were obtained with a conventional lower-body gait analysis protocol over three trials per task. To assess the repeatability with standard indices, a representative subset of 10 subjects underwent three repetitions of the entire motion capture session. Extracted parameters with good repeatability included maximum and minimum axial rotation during turning, local extremes of the flexion curves during gait tasks, and stride times. These specific repeatable parameters can be used for task selection or power analysis when planning future clinical studies.

Age-related changes in kinematics of the knee joint during deep squat.

Researchers frequently use the deep knee squat as a motor task in order to evaluate the kinematic performance after total knee arthroplasty. Many authors reported about the kinematics of a normal squatting motion, however, little is known on what the influence of aging is. Twenty-two healthy volunteers in various age groups (range 21-75 years) performed a deep knee squat activity while undergoing motion analysis using an optical tracking system. The influence of aging was evaluated with respect to kinematics of the trunk, hip, knee and ankle joints. Older subjects required significantly more time to perform a deep squat, especially during the descending phase. They also had more knee abduction and delayed peak knee flexion. Older subjects were slower in descend than ascend during the squat. Although older subjects had a trend towards less maximal flexion and less internal rotation of the knee compared to younger subjects, this difference was not significant. Older subjects also showed a trend towards more forward leaning of the trunk, resulting in increased hip flexion and anterior thoracic tilt. This study confirmed that some aspects of squat kinematics vary significantly with age, and that the basic methodology employed here can successfully detect these age-related trends. Older subjects had more abduction of the knee joint, and this may indicate the load distribution of the medial and lateral condyles could be different amongst ages. Age-matched control data are therefore required whenever the performance of an implant is evaluated during a deep knee squat.

Tibial rotation in single- and double-bundle ACL reconstruction: a kinematic 3-D in vivo analysis.

PURPOSE: The effect of double-bundle ACL reconstruction on knee kinematics has recently been studied by several authors under controlled laboratory conditions however little evidence has been derived from dynamic in vivo evaluations. This study hypothesized that tibial rotation during pivoting motor tasks would be better restored after double-bundle ACL reconstructions when compared with single-bundle procedures. METHODS: Twenty patients with a chronic ACL rupture were randomly assigned to receive a single- or double-bundle ACL reconstruction. Both knees were evaluated pre-operatively by kinematic 3-D gait analysis while performing low- and high-demand motor tasks, including pivoting. At 6 months post-operatively, measurements were repeated in 16 patients. Ten healthy, sex- and age-matched subjects with no history of lower limb pathology formed the control group. The tibial rotational excursion was set as the dependent variable. RESULTS: The results indicate that at 6 months after surgery both "anatomic" single- and double-bundle ACL reconstruction are able to restore tibial rotational excursion when compared with the contralateral knees and with control knees from uninjured subjects. Chronic ACL-deficient patients show an increase in tibial rotation in both knees during high-demand pivoting tasks. CONCLUSIONS: Both "anatomic" single- and double-bundle ACL reconstruction adequately restore tibial rotational excursion in a human, "in vivo" kinematic model. As knee stability measurements by in vivo kinematic 3-D analysis more accurately represent actual knee loading during activities, the results of this study might better correlate with functional outcome after ACL reconstructions compared with static knee stability tests or ex vivo laboratory experiments. In such, the results of this dynamic study do not support the theoretical advantage of a double-bundle ACL reconstruction over an "anatomic" single-bundle ACL reconstruction.

Range of motion and repeatability of knee kinematics for 11 clinically relevant motor tasks.

Standard gait analysis reports knee joint rotations in the three anatomical planes without addressing their different levels of reliability. Most clinical studies also restrict analysis to knee flexion-extension, because knee abduction-adduction and axial rotation are small with respect to the corresponding amount of measurement artefact. This study analyses a set of 11 motor tasks, in order to identify those that are adequately repeatable and that can induce greater motion at the knee than walking. Ten volunteers (mean ± SD age: 29 ± 9 years) each underwent three motion analysis sessions on different days with a standard gait analysis system and protocol. In each session they performed normal walking, walking with sidestep and crossover turns, ascent onto and descent off a step, descent with sidestep and crossover turns, chair rise, mild and deep squats, and lunge. Range and repeatability of motions in the three anatomical planes were compared by ANOVA. The sidestep turns showed a range of axial rotation significantly larger than that in walking (about 8°), while maintaining similar levels of repeatability. Ascent, chair rise, squat, and lunge showed greater flexion ranges than walking; among these, ascent was the most repeatable. The results show that turning increases knee axial rotation in young subjects significantly. Further, squats and lunges, currently of large interest in orthopaedics and sports research, have smaller repeatability, likely accounted for to the smaller constraints than in the traditional motor tasks.

How can push-off be preserved during use of an ankle foot orthosis in children with hemiplegia? A prospective controlled study.

Several studies indicated that walking with an ankle foot orthosis (AFO) impaired third rocker. The purpose of this study was to evaluate the effects of two types of orthoses, with similar goal settings, on gait, in a homogeneous group of children, using both barefoot and shoe walking as control conditions. Fifteen children with hemiplegia, aged between 4 and 10 years, received two types of individually tuned AFOs: common posterior leaf-spring (PLS) and Dual Carbon Fiber Spring AFO (CFO) (with carbon fibre at the dorsal part of the orthosis). Both orthoses were expected to prevent plantar flexion, thus improving first rocker, allowing dorsiflexion to improve second rocker, absorbing energy during second rocker, and returning it during the third rocker. The effect of the AFOs was studied using objective gait analysis, including 3D kinematics, and kinetics in four conditions: barefoot, shoes without AFO, and PLS and CFO combined with shoes. Several gait parameters significantly changed in shoe walking compared to barefoot walking (cadence, ankle ROM and velocity, knee shock absorption, and knee angle in swing). The CFO produced a significantly larger ankle ROM and ankle velocity during push-off, and an increased plantar flexion moment and power generation at pre-swing compared to the PLS (<0.01). The results of this study further support the findings of previous studies indicating that orthoses improve specific gait parameters compared to barefoot walking (velocity, step length, first and second ankle rocker, sagittal knee and hip ROM). However, compared to shoes, not all improvements were statistically significant.

Do dynamic and static clinical measurements correlate with gait analysis parameters in children with cerebral palsy?

The present study documents the correlation between gait analysis data and clinical measurements and evaluates the combined predictive value of static and dynamic clinical measurements on gait data of children with cerebral palsy. Two hundred patients were evaluated using a set of measurements of range of motion (ROM), alignment, spasticity, strength and selectivity, and by three-dimensional gait analysis. Fair to moderate correlations were found between clinical measurements and gait data, the overall highest correlation being 0.60. Clinical data of strength and selectivity had the highest degree of significant correlations with gait data, compared to the ROM and spasticity. ROM, spasticity and strength measurements for the hip in the coronal plane and spasticity of rectus femoris most frequently showed fair to moderate correlations to gait data. Time and distance and EMG parameters mainly correlated with strength and selectivity parameters. Unexpectedly, alignment parameters only fairly correlated with hip rotation in stance. Multiple regression analysis revealed that adding dynamic clinical measurements (spasticity, strength and selectivity) to a static model (ROM) enhanced the link between clinical measurements and gait data. The variance of gait parameters was better explained by a combined model of static and dynamic clinical measurements, compared to a purely static model. However, R(2)-values were low. Gait analysis data cannot be sufficiently predicted by a combination of clinical measurements. The independence of the measurements supports the notion that both, clinical examination and gait analysis data provide important information for delineating the problems of children with CP.