Can Strength Training Predictably Improve Gait Kinematics? A Pilot Study on the Effects of Hip and Knee Extensor Strengthening on Lower-Extremity Alignment in Cerebral Palsy

Functional and Applied Biomechanics Section, Rehabilitation Medicine Department, NIH Clinical Center, Bldg 10, Room 1-1469, Bethesda, MD 20892, USA.
Physical Therapy (Impact Factor: 2.53). 12/2009; 90(2):269-79. DOI: 10.2522/ptj.20090062
Source: PubMed


Computer simulations have demonstrated that excessive hip and knee flexion during gait, as frequently seen in ambulatory children with cerebral palsy (CP), can reduce the ability of muscles to provide antigravity support and increase the tendency of hip muscles to internally rotate the thigh. These findings suggest that therapies for improving upright posture during gait also may reduce excessive internal rotation.
The goal of this study was to determine whether strength training can diminish the degree of crouched, internally rotated gait in children with spastic diplegic CP.
This was a pilot prospective clinical trial.
Eight children with CP participated in an 8-week progressive resistance exercise program, with 3-dimensional gait analysis and isokinetic testing performed before and after the program. Secondary measures included passive range of motion, the Ashworth Scale, and the PedsQL CP Module. To identify factors that may have influenced outcome, individual and subgroup data were examined for patterns of change within and across variables.
Strength (force-generating capacity) increased significantly in the left hip extensors, with smaller, nonsignificant mean increases in the other 3 extensor muscle groups, yet kinematic and functional outcomes were inconsistent. The first reported subject-specific computer simulations of crouch gait were created for one child who showed substantial benefit to examine the factors that may have contributed to this outcome.
The sample was small, with wide variability in outcomes.
Strength training may improve walking function and alignment in some patients for whom weakness is a major contributor to their gait deficits. However, in other patients, it may produce no change or even undesired outcomes. Given the variability of outcomes in this and other strengthening studies in CP, analytical approaches to determine the sources of variability are needed to better identify those individuals who are most likely to benefit from strengthening.

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    • "The resistance pad was attached approximately 3 cm above the lateral malleolus. The total range of motion was set as 708, from 908 of knee flexion to 208 of knee extension; 08 being full extension (Ayalon et al., 2000; Damiano, Arnold, Steele, & Delp, 2010; dos Santos et al., 2013). Additional back support was provided, when necessary, to ensure biomechanical alignment between rotational axis of both knee and dynamometer. "
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    ABSTRACT: This study aimed to investigate the relationship between sit-to-stand (STS) movement, knee extensor torque and social participation in children with cerebral palsy (CP). Seven spastic hemiplegic CP patients (8.0±2.2 years), classified by the Gross Motor Function Classification System as I and II, and 18 typical children (8.4±2.3 years) participated in this study. Trunk, hips, knees, and ankles angles and temporal variables of STS movement were obtained by means of kinematics evaluation. Isokinetic evaluation was performed at 60°/s in the concentric passive mode to measure knee extensors torque. Social participation was assessed by the Assessment of Life Habits for Children (LIFE-H) scale. Results showed that children with spastic hemiplegic CP have lower knee extensor torque in the affected limb and restriction in social participation in dimensions related with fine motor control and language skills when compared to their typical peers. Except for ankle excursion in frontal plane, and ankle excursion and range in transverse plane, patients were similar to typical children regarding the strategies adopted to perform the STS movement, as well as in the participation dimensions related with gross motor function. Moreover, we found a significant non-linear correlation between knee extensors torque and some lower limb and trunk angles for children with CP. Therefore, during evaluation and rehabilitation processes, impairments in body functions and structures should be related with how much they affect a child's ability to perform functional activities, so rehabilitation protocols could be focused on individual needs.
    Research in developmental disabilities 04/2013; 34(6):2023-2032. DOI:10.1016/j.ridd.2013.03.021 · 4.41 Impact Factor
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    • "Biomechanical studies are increasingly utilizing such a platform to derive joint kinematics, to estimate neuromuscular responses, and to understand the cause–effect relationships in musculoskeletal dynamics (e.g. Arnold et al., 2007; Damiano et al., 2010; Fox and Delp, 2010; Riley et al., 2010; Xiao and Higginson, 2010). Although modeling platforms such as OpenSim provide a relatively easy path towards creating musculoskeletal simulations, the veracity of these simulations persists as an issue of concern. "
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    ABSTRACT: This study assessed the accuracy of surface-measured OpenSim-derived tibiofemoral kinematics in functional activities. Ten subjects with unilateral, isolated grade II PCL deficiency performed level running and stair ascent. A dynamic stereo radiography (DSX) system and a Vicon motion capture system simultaneously measured their knee or lower extremity movement. Surface marker motion data from the Vicon system were used to create subject-specific models in OpenSim and derive the tibiofemoral kinematics. The surface-measured model-derived tibiofemoral kinematics in all six degrees of freedom (DOFs) were then compared with those measured by the DSX as the benchmarks. The differences between surface- and DSX-measured tibiofemoral kinematics were found to be substantial: the overall mean (±SD) RMS differences during running were 9.1±3.2°, 2.0±1.2°, and 6.4±4.5° for the flexion-extension, abduction-adduction, and internal-external rotations, respectively, and 7.1±3.2mm, 8.8±3.7mm, and 1.9±1.2mm for anterior-posterior, proximal-distal, and medial-lateral translations, respectively. The differences were more pronounced in relatively higher speed running than in stair ascent. It was also found that surface-based measures significantly underestimated the mean as well as inter-subject variability of the differences between PCL-injured and intact knees in abduction-adduction, internal-external rotations, and anterior-posterior translation.
    Journal of Biomechanics 09/2012; 45(15):2719-23. DOI:10.1016/j.jbiomech.2012.08.007 · 2.75 Impact Factor
    • "Despite the availability of health service frameworks (National Services Framework, 2005)[14] that promote rehabilitation for persons with long-term neurological conditions (LTNC) such as CP; as also clinical guidelines and standards,[15–18] gaining access to the appropriate rehabilitation services continues to be a challenge[121920]. One reason for this is the relatively poor understanding of the specific benefits that may be derived from rehabilitation in the context of this neurological disease.[13] "
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    ABSTRACT: To examine the outcome of inpatient rehabilitation for cerebral palsy (CP), using the Australian Rehabilitation Outcomes Center (AROC) database. De-identified data from the AROC database was analyzed for all rehabilitation admissions during 2003 - 2008, using four classes for the functional level. The outcomes included: Functional Independence Measure (FIM) scores, FIM efficiency, hospital length of stay (LOS), and discharge destination. Of 141 case episodes 56.7% were female, mean age 48.5 years, 87.2% were discharged to the community and 64.5% (n = 91) were in the lowest functional classes (217, 218, and 219). The majority of CP patients were treated in the public hospital system (66.7% versus 33.3%), and had a slightly longer LOS compared with those treated in private facilities (22.6 versus 17.9 days, mean difference - 4.7 days, 95% CI - 9.2 to - 0.2, P = 0.041). The FIM for all classes (216 - 218) showed significant functional improvement during the admission (P = 0.001). As expected those in the most functionally impaired classes showed most change (FIM change: 16.6 in class 217, 15.3 in class 218). FIM efficiency was the highest in classes 217 compared to the other classes. The year-to-year trend demonstrated a mixed pattern for hospital LOS and was not significant (P = 0.492). The AROC dataset is a valuable research tool for describing rehabilitation outcomes. However, more specific information needs to be collected alongside the core AROC data, to allow a more meaningful evaluation of outcomes for CP rehabilitation.
    Journal of Neurosciences in Rural Practice 03/2011; 2(1):43-9. DOI:10.4103/0976-3147.80097
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