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Background
Several investigators have advocated the use of gait analysis for planning surgery and therapy treatments for children with cerebral palsy (CP). Although their rationale appears sound, it has not been supported by clinical outcome studies demonstrating its efficacy beyond visual analysis of gait abnormalities routinely performed by clinicians.
An assessment conducted by the BlueCross BlueShield Association Technology Evaluation Center (2002) concluded that “[t]he evidence does not permit conclusions on whether the use of gait analysis for evaluation of children with cerebral palsy improves health outcomes or is as beneficial as established alternatives.” The assessment noted that several studies have reported that treatment decisions were affected by the results of gait analysis; these studies, however, do not demonstrate whether clinical outcomes were improved by basing treatment decisions on gait analysis. The assessment identified only 1 study that directly addressed the question of whether gait analysis improves patient outcomes, compared with standard clinical assessment. This retrospective study (Lee et al, 1992) reported on the outcomes of 23 children with CP, 15 of whom were treated according to the recommendation of gait analysis data plus clinical assessment, and 8 of whom were treated according to clinical assessment alone. Of the 7 children who were classified as not improved, 5 had been treated according to clinical assessment alone. The TEC assessment noted several problems with this study, including small numbers of study subjects, lack of consideration of confounding factors, and vague definition of outcomes. Most important, however, it was not reported whether children analyzed as treated according to gait analysis data underwent treatments discordant with the recommendations of clinical assessment alone or in agreement with clinical assessment alone (BCBSA, 2002). The TEC assessment notes that, if it is the latter, then the study is severely flawed and can not be used to compare clinical assessment and gait analysis. The TEC assessment concluded that, “[i]n the absence of any well-designed observational or randomized controlled trials, no conclusion can be drawn about whether gait analysis in the clinical evaluation and treatment of cerebral palsy has an effect upon health outcomes.”
Gait analysis studies that have been published since the TEC assessment was released suffer from similar limitations as previous studies, in that they have not included outcomes of internal comparison groups of children with CP who were managed based on clinical assessment alone. Comparisons of outcomes between studies (i.e., comparisons of outcomes of studies where gait analysis was used with studies where gait analysis was not used) is problematic due to confounding factors that may account for differences in outcomes (such as differences in surgical technique and experience, characteristics of study subjects, methods of assessing outcomes, etc.).
Several studies have reported that treatment decisions are affected by the results of gait analysis (Lofterod et al, 2007; Kay et al, 2000; Molenaers et al, 2006; Wren et al, 2005); these studies, however, do not demonstrate whether clinical outcomes are improved by basing treatment decisions on gait analysis. Similarly, studies examining correlations (or the lack thereof) between clinical measurements and quantitative gait analysis (Desloovere et al, 2006; Kawamura et al, 2006) do not prove that the quantitative measurements provided by gait analysis alter the management of patients such that clinical outcomes are improved.
One small retrospective study evaluated the impact of computerized gait analysis on clinical outcomes (Chang et al, 2006). The study included 10 patients with CP and 10 age- and sex-matched controls. Children in the control group chose not to follow the gait analysis recommendation and chose a non-surgical treatment approach, whereas children in the gait analysis group followed a physician's recommendation for gait analysis. The results documented that 74 % of patients in the control group had no change or a negative outcome, 26 % in the control group had a positive outcome. Of the gait analysis group 61 % had no change or a negative outcome, while 44 % of this group had a positive outcome. While the results of this study suggest that gait analysis recommendations may improve clinical outcomes, the control group did not undergo surgery, whereas those in the gait analysis group did. Therefore, it is not possible to determine the relative contributions of gait analysis and surgery.
A study by Wren et al (2009) is a retrospective analysis of numbers of procedures and costs in children whose surgery was planned by gait analysis and those whose surgery was performed without gait analysis. The investigators found no significant differences overall in total numbers of procedures and costs between the 2 groups. Limitations of the study include its retrospective nature and lack of randomized assignment. Since the study was retrospective, the authors were unable to assess other outcomes such as function, participation, and quality of life, which are important outcomes that need to be examined in future prospective studies.
Dobson and colleagues (2007) evaluated the validity of existing classifications of gait deviations in children with CP. The authors noted that numerous efforts have been made to develop classification systems for gait in CP to assist in diagnosis, clinical decision-making and communication. The authors examined the internal and external validity of gait classifications in 18 studies, including their sampling methods, content validity, construct validity, reliability and clinical utility. The authors found that half of the studies used qualitative pattern recognition to construct the gait classification and the remainder used statistical techniques such as cluster analysis. Few adequately defined their samples or sampling methods. The authors found that most classifications were constructed using only sagittal plane gait data, and that many did not provide adequate guidelines or evidence of reliability and validity of the classification system. No single classification addressed the full magnitude or range of gait deviations in children with CP. The authors concluded that, although gait classification in CP can be useful in clinical and research settings, the methodological limitations of many classifications restrict their clinical and research applicability.
Lofterod and Terjesen (2008) evaluated the outcome of orthopedic surgery in ambulant children with CP, when the orthopedic surgeons followed the recommendations from pre-operative 3-dimensional gait analysis. A total of 55 children (mean age of 10 years and 11 months) were clinically evaluated by orthopedic surgeons who proposed a surgical treatment plan. After gait analysis and subsequent surgery, 3 groups were defined. In group A, there was agreement between clinical proposals, gait analysis recommendations, and subsequent surgery in 128 specific surgical procedures. In group B, 54 procedures were performed based on gait analysis, although these procedures had not been proposed at the clinical examination. In group C, 55 surgical procedures that had been proposed after clinical evaluation were not performed because of the gait analysis recommendations. The children underwent follow-up gait analysis 1 to 2 years after the initial analysis. The kinematic results were satisfactory, with improvement in most of the gait parameters in children who had undergone surgery and no significant deterioration in those who were not operated. In group A, there were significant improvements in maximum hip extension in stance, minimum knee flexion in stance, timing of maximum knee flexion in swing and knee range of motion (ROM), maximum ankle dorsiflexion in stance, and mean femur rotation in stance. In group B, there were significant improvements in maximum hip extension in stance, minimum knee flexion in stance, and knee ROM. The authors concluded that gait analysis was useful in confirming clinical indications for surgery, in defining indications for surgery that had not been clinically proposed, and for excluding or delaying surgery that was clinically proposed. The findings of this study need to be validated by well-designed studies.
An additional important factor that limits the ability to interpret the evidence on gait analysis is the fact that the technical parameters, diagnostic variables, and outcome measures vary among studies. Some of the differences included the number and placement of video cameras, reflective markers, and force plates; number and type of gait parameters that are measured; and variations in the use of EMG data. Study participants are heterogenous with regard to the type of gait disorder and clinical history. Studies of the impact of computerized gait analysis on patient management evaluated different types of surgical procedures, and varied in the number and type of muscles that were operated on. In addition, few studies include follow-up data.
Narayanan (2007) reviewed the scientific literature to describe the role of gait analysis in the orthopedic management of ambulatory children with CP and examined the current best evidence to support these roles. The author stated that although gait analysis has been shown to alter decision making, there is little evidence that the decisions based on gait analysis lead to better outcomes. Consequently, clinical gait analysis remains controversial, with wide variation in the rates of utilization of gait analysis in the management of children with ambulatory CP. The author stated that the time is ripe for clinical trials and cohort studies to provide the evidence to establish the appropriate utilization of this technology.
Randomized controlled clinical trials to compare outcomes of surgery planned with and without gait analysis are currently ongoing. One of these studies, sponsored by the Federal Agency for Healthcare Research and Quality (AHRQ) and conducted at 2 children's hospitals in Los Angeles, has been completed, and its results (Wren, et al., 2012) are reported below. The AHRQ explained why this study is needed: "Gait analysis testing has been used to assist orthopedic surgeons in developing treatment plans for children with gait abnormalities, particularly children with cerebral palsy. Previous studies have shown that gait analysis testing significantly impacts surgical decision-making for these patients. However, no controlled studies have been done to determine whether gait analysis and the subsequent changes in surgical decision-making affect clinical outcomes. Consequently, the use of gait analysis in clinical practice remains controversial. The purpose of this study is to conduct a randomized controlled trial to assess the effects of preoperative gait analysis on surgical outcomes in ambulatory children with cerebral palsy" (AHRQ, 2005).
Another randomized controlled clinical study of gait analysis, funded by the Canadian government, is being conducted at 2 children's hospitals in Toronto. The study description explains the need for this trial: "Pre-operative planning is based on the physical examination and visual (observational) analysis of the child's gait. In some centres, patients undergo additional gait analysis in a motion laboratory. While gait laboratory analysis is accepted as an important research tool, there is controversy about its clinical utility in decision making for the surgical management of this population. To date, no clinical trials have been undertaken to answer this question, and the appropriate clinical utilization of this technology is yet to be established. The consequence of this uncertainty is that ambulatory children with cerebral palsy are either being deprived of a useful assessment tool in some centres, or alternatively they are being subjected to an unnecessary evaluation that is both expensive and time consuming in other centres" (Hospital for Sick Children, 2007). Both of these randomized controlled clinical trials will examine the impact of gait analysis on a number of parameters, the most important of which relate to clinical outcomes (i.e., improvements in function and quality of life), as opposed to intermediate outcomes.
Maquet and colleagues (2010) evaluated gait characteristics during simple and dual task in patients with mild cognitive impairment (MCI) and compared them with those of healthy elderly subjects and mild Alzheimer's disease (AD) patients. These researchers proposed a gait analysis to appreciate walking (simple task and dual task) in 14 MCI, 14 controls and 6 AD subjects who walked at their preferred speed. A 20-second period of stabilized walking was used to calculated stride frequency, stride length, symmetry and regularity. Speed walking was measured by electrical photocells. Variables measured during simple and dual tasks showed an alteration of motor function as well in mild AD patients as in MCI patients. The authors concluded that at the end of this preliminary study, they defined a specific gait pattern for each cognitive profile. They stated that further researches appear necessary to enlarge the study cohort. Furthermore, in a review on clinical gait analysis, Chapin (2010) stated that additional research documenting the value of incorporating clinical gait analysis in the treatment planning process may ultimately change the payment patterns of insurers.
Ornetti and colleagues (2010) stated that kinematic gait analysis consisting of measuring gait parameters (e.g., dynamic joint angles, gait speed, and stride length) is a potential outcome measure in osteoarthritis (OA). These investigators evaluated the psychometric properties of gait analysis. A systematic literature search was performed in PubMed and the Cochrane database until January 2008 by selecting manuscripts assessing any psychometric property of gait analysis in knee or hip OA. These researchers assessed feasibility (access, cost, and time); reliability; discriminant capacity by differences between OA and non-OA patients; construct validity by correlation between gait analysis and OA symptoms: pain or functional disability (Lequesne/WOMAC); and responsiveness by improvement of gait analysis after treatment of OA using effect size. Among the 252 articles identified, the final analysis included 30 reports (i.e., 781 knee OA patients and 343 hip OA patients). Gait analysis presents various feasibility issues and there was limited evidence regarding reliability (3 studies; 67 patients). Discriminant capacity showed significant reduction of gait speed, stride length and knee flexion in OA patients compared to healthy subjects. Few data were available concerning construct validity (3 studies; 79 patients). Responsiveness of gait speed was moderate to large with effect size ranging respectively from 0.33 to 0.89 for total knee replacement, and from 0.50 to 1.41 for total hip replacement. The authors concluded that available data concerning validity and reliability of kinematic gait analysis are insufficient to date to consider kinematic parameters as valuable outcome measures in OA. They stated that further studies evaluating a large number of patients are needed.
Calhoun et al (2011) compared kinematic and kinetic gait patterns in children with autism versus age-matched controls. A total of 12 children with autism and 22 age-matched controls participated in the study. An 8-camera motion capture system and 4 force plates were used to compute joint angles and joint kinetics during walking. Parametric analyses and principal component analyses were applied to kinematic and kinetic waveform variables from the autism and control groups. Group differences in parameterization values and principal component scores were tested using 1-way ANOVAs and Kruskal-Wallis tests. Significant differences between the autism and control group were found for cadence, and peak hip and ankle kinematics and kinetics. Significant differences were found for 3 of the principal component scores: (i) sagittal ankle moment principal component one, (ii) sagittal ankle angle principal component one, and (iii) sagittal hip moment principal component two. Results suggest that children with autism demonstrate reduced plantar-flexor moments and increased dorsiflexion angles, which may be associated with hypotonia. Decreased hip extensor moments were found for the autism group compared to the control group, however, the clinical significance of this result is unclear. This study has identified several gait variables that were significantly different between autism and control group walkers. This is the first study to provide a comprehensive analysis of gait patterns in children with autism. The role of gait analysis, if any, in the managment of children with autism has yet to be established.
The American Association of Electrodiagnostic Medicine/American Academy of Physical Medicine and Rehabilitation's technology review on "Dynamic electromyography in gait and motion analysis" (1999) concluded that "its utility in pre-operative planning has not been proven in well-designed, large, multi-center studies. There remains many legitimate differences of opinion as to the relative benefits of surface versus fine-wire techniques that future studies will need to resolve. Also in doubt is the best way of determining onset of electrical activity and other technical variables. Dynamic EMG, as part of comprehensive motion analysis, has found applications in the optimization of athletic performance. The subjects in these studies are not patients in the classic sense and did not necessarily carry any type of medical diagnosis".
A randomized controlled clinical trial (Wren, et al., 2012) found no significant difference in primary outcome measures and most secondary outcome measures with use of gait analysis in cerebral palsy surgery. This study examined the impact of gait analysis on surgical outcomes in 156 ambulatory children with cerebral palsy through a randomized controlled trial. Patients underwent gait analysis and were randomized to two groups: Gait Report group (n = 83), where the referring surgeon received the patient’s gait analysis report, and Control group (n = 73), where the surgeon did not receive the gait report. Outcomes were assessed pre- and 1.3 + 0.5 years post-operatively. An intent-to-treat analysis compared outcomes between the two groups. The primary outcome measures were the walking scale of the Gillette Functional Assessment Questionnaire (FAQ), the Gait Deviation Index (GDI), and the oxygen cost of walking (O2 cost). Secondary outcome measures included the gross motor function measure (GMFM-66) and health-related quality of life questionnaires (Child Health Questionnaire (CHQ), Pediatric Outcomes Data Collection Instrument (PODCI), and Pediatric Evaluation and Disability Inventory (PEDI). The outcomes that differed significantly between groups were change in health component of the CHQ, which was rated as much better for 56% (46/82) of children in the Gait Report group compared with 38% (28/73) in the Control group (p = 0.04), and the upper extremity physical function component of the PODCI. There were no significant differences in outcomes between the Gait Report group and the Control group in the primary outcome measures: the FAQ, the GDI, and O2 cost. There were also no significant differences in most secondary outcomes, including the GMFM-66, all four components of the PEDI, and components of the CHQ other than change in health (i.e., global health, physical functioning, role/social limitations - physical, pain/discomfort, self esteem, general health perception, parental impact - emotional, and parental impact - time), and components of the PODCI other than upper extremity physical function (i.e., sports/physical function, transfer/basic mobility, pain/comfort, and global functioning). The authors posited that one potential reason for the lack of difference between the Gait Report group and the Control group for most measures was because surgeons who received gait reports followed the report recommendations less than half (42%) of the time.
In a cohort study, Chow and colleagues (2012) examined the velocity-dependent change in medial gastrocnemius (MG) activity during the stance phase of gait in patients with moderate-to-severe resting hypertonia after stroke or traumatic brain injury (TBI). Convenience sample of patients with chronic TBI and stroke (n = 11 each), and age- and sex-matched healthy controls (n = 22). Main outcome measures included frequency and gain (steepness) of positive (greater than 0) and significant positive (greater than 0 and goodness of fit p ≤ 0.05) electromyogram-lengthening velocity (EMG-LV) linear regression slope in MG during the stance phase of gait. Positive and significant positive slopes were found significantly more often on the more affected (MA) than less affected (LA) side in patients with TBI but not stroke. Both the frequencies of positive and significant positive slopes on the MA side in patients with TBI were also significantly higher than in controls. However, neither the gain of positive nor significant positive EMG-LV slope was different between the MA and LA sides or in comparison with controls. Positive slope parameters were not related to Ashworth score on the MA side. The authors concluded that the frequency and gain of positive EMG-lengthening slope did not effectively differentiate patients from controls, nor were they related to the resting muscle hypertonia. Motor output during MG lengthening in the stance phase of gait is apparently not exaggerated or related to resting hypertonia in patients with chronic TBI and stroke. Thus, changes in gait during stance cannot be ascribed to increased stretch reflex activity in MG muscle after acquired brain injury.
An evidence review of management of children with cerebral palsy (Narayanan, 2012) stated that there is good evidence that gait analysis does alter surgical decision-making at least some of the time. However, "there remain concerns about the reliability (reproducibility) of these decisions or whether implementing these recommendations would result in different, let alone better outcomes" (Narayanan, 2012). The review reported on one study of gait analysis that found that, when the same gait analysis data were examined by gait analysis experts from 6 different institutions, there was only slight to moderate agreement in the list of problems generated by the experts (citing Skaggs, et al., 2000). Agreement about specific surgical recommendations was similarly poor. The review explained that, although gait analysis data are themselves objective, there is subjectivity in interpretation even among experts, with diagnoses and treatment recommendations varying significantly by surgeon or institution. The evidence review stated that, in another study (citing Noonan, et al., 2003), there was variability in the kinematic data generated in 4 different motion laboratories that tested the same 11 patients. Although the clinical significance of some of this variability has been challenged, the treatment recommendations generated from these data were different across the 4 centers for 9 of the 11 patients. The author of the review stated: "Variability in the interpretation of gait data reflects the prevailing uncertainty (or controversies) about the causes and/or significance of specific findings and will only be resolved with ongoing clinical research and experience using gait analysis. Similarly, variability in treatment recommendations based on the same gait data also reflects differences of opinion about best strategies to deal with specific problems, which in turn can only be definitively resolved with comparative clinical trials or observational studies" (Narayanan, 2012). The review author concluded that "as long as such significant variability exists, the recommendation that gait analysis is essential for all preoperative decision-making before multilevel orthopaedic surgery in clinical (as opposed to research) practice is currently not supported by the literature" (Narayanan, 2012).
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