Gait Analysis: The link to clinical outcomes

The effect of any diagnostic test is difficult to measure. But research suggests gait analysis influences treatment decision making, which in turn affects patient management and, ultimately, clinical results.

iStockphoto.com/Aaron Monts

Gait analysis is a specialized medical technology used to evaluate walking, particularly in patients with complex walking problems such as children with cerebral palsy. In a clinical setting, gait analysis may be used as a diagnostic test or as an outcome measure. This review focuses on the former application.

A comprehensive clinical gait analysis test includes physical examination, videotaping, computerized motion tracking of body segments, recording of ground reaction forces between the feet and floor, and dynamic electromyography. Motions, forces, and muscle firing patterns are measured to assess the patient’s status and to develop an appropriate treatment plan. Each component of gait analysis testing can be performed separately, but the data are most useful when viewed together in a comprehensive evaluation.

Although gait analysis allows for a more accurate assessment of gait deviations than visual gait assessment,^1,2 the use of gait analysis in guiding the care of individual patients in clinical practice remains controversial. Proponents contend that gait analysis provides valuable information essential for optimal management of individual patients with walking problems. Opponents argue that gait analysis adds unnecessary cost and that any benefits to an individual patient remain unproven, although gait analysis may remain an appropriate clinical research tool.

Evaluating the clinical impact of a diagnostic test is complex because diagnostic tests have an indirect effect on patient outcomes.^3,4 However, research suggests that by influencing the treatment decision-making process, gait analysis may affect patient management and, consequently, clinical outcomes (Figure 1).

Impact on treatment decision-making
A number of studies have clearly demonstrated that gait analysis alters surgical decision-making and changes the treatment patients receive.^5-9 These studies generally compare treatment plans without gait analysis to treatment plans for the same patients that do utilize gait analysis. Most studies have focused on the use of pre-operative gait analysis in surgical planning for children with cerebral palsy and other diagnoses^5,6,8,9 or in patients with specific impairments like spastic equinovarus.⁷ One study examined post-operative treatments including bracing, physical therapy, and additional surgery.¹⁰ In some studies, the two treatment plans being compared (with and without gait analysis) are proposed by the same clinician.^5-7 In other studies, the plan without gait analysis is proposed by a referring physician, and the plan with gait analysis is proposed by the gait laboratory team, which may or may not include the referring physician.^8,9 The findings have been consistent, regardless of the details of the study design.

The results of these studies indicate that the treatment plans with and without gait analysis differ in a high percentage of patients (52% to 89%) and procedures (40% to 51%).^5-10 In addition, in patients undergoing gait analysis there are changes between the initial treatment plan and the treatment ultimately performed. Two of these studies found that 37% to 39% of the procedures planned before gait analysis were not ultimately done, and 28% to 40% of the procedures actually done were not planned before gait analysis.^8,9 The change in actual treatment is likely due, at least in part, to the addition of gait analysis since gait analysis recommendations are followed in a high percentage of patients (with 77% having an exact match between the surgeries recommended by gait analysis and the surgeries ultimately performed ¹¹) and specific surgical procedures (92% to 93%).^9,11

Recently, we have used data from a randomized, controlled trial to further examine the influence of gait analysis on surgical decision-making for children with cerebral palsy. The randomized design has the advantage of providing a control group against which the gait analysis group can be compared.

One hundred fifty three surgical candidates underwent preoperative gait analysis testing and were randomized to two groups, where the referring surgeon did or did not receive a copy of the patient’s gait analysis report. When the gait analysis disagreed with the referring surgeon’s original treatment plan, the gait analysis recommendation was followed in a significantly higher percentage of cases in the group receiving the gait analysis report prior to surgery (21% vs. 10%, p<0.001). In addition, when the gait analysis agreed with a surgeon’s planned procedure, the planned procedure was done in a significantly higher percentage of cases in the group receiving the gait report (91% vs. 67%, p<0.001). These results indicate that gait analysis not only changes surgical decision-making as previously reported, but that it also reinforces decision-making and increases the surgeon’s confidence to proceed with a planned surgery when the gait analysis recommendations agree with the original treatment plan.

Impact on clinical outcomes
There are currently no clinical outcomes data available from randomized, controlled trials studying the impact of gait analysis on treatment outcomes and decision-making, although two such trials are currently being conducted. Randomized trials of clinically available procedures are often difficult to justify due to ethical concerns (i.e., the ethics of withholding a potentially beneficial procedure or information from a patient’s plan of care in order to create a control group). This predicament is not unique to gait analysis and often necessitates the use of other study designs such as case-control studies or case series comparisons.^3,4

Several studies have used such designs to evaluate the effect of gait analysis on patient outcomes.^12-17 These studies generally compare outcomes between patients whose treatment followed gait analysis recommendations and patients whose treatment did not follow gait analysis recommendations. The results indicate better gait and functional outcomes when the treatment follows gait analysis recommendations. Specifically, function improves when surgery is done and is consistent with gait analysis recommendations, function is maintained when no surgery is done as recommended by gait analysis, and function deteriorates when surgery is recommended by gait analysis but not done.

The first study of this type graded outcomes as improved or not improved based on temporal and sagittal gait parameters in a small number (n=22) of children with spastic diplegic cerebral palsy.¹⁴ Of 15 children who had surgery in accordance with gait analysis recommendations, 13 improved, and two did not improve because the outcome measures did not capture the impairment being addressed (rotational alignment). Of seven patients who did not have the recommended surgeries performed, two had surgeries similar to those recommended by gait analysis and improved, while the other five had surgeries different from the gait analysis recommendations and did not improve. This study provided the first indication that patients may have better outcomes when their treatment follows gait analysis recommendations.

Several recent studies have continued this line of investigation, comparing groups of patients with CP whose treatment followed gait analysis recommendations to different extents. Gough and Shortland¹⁷ reported that outcome measures related to contracture and gait improved in children who had multilevel surgery as recommended by gait analysis, worsened in children who did not undergo surgery despite having surgery recommended by gait analysis, and remained stable in children who had no surgery as recommended by gait analysis. Filho et al¹³ observed improvement in gait in surgical patients whose surgery agreed, to some extent, with gait analysis recommendations. The significance of the improvement was related to the degree to which the gait analysis recommendations were followed, and no improvement was observed in patients who had surgical or non-surgical treatment that was completely different from that recommended by gait analysis. Lofterod et al¹⁵ reported satisfactory kinematic outcomes in pediatric gait laboratory patients who received surgical or non-surgical treatment consistent with gait analysis recommendations. These studies suggest that gait analysis is useful in defining indications for surgical and non-surgical treatment and that treatment following gait analysis recommendations is associated with better outcomes.

One study has compared outcomes during periods before and after gait analysis was added to the management protocol for children with cerebral palsy.¹⁸ One hundred twenty two patients managed without gait analysis from 1985 to 1989 were compared against 170 patients managed with input from gait analysis from 1996 to 1997 (after the gait analysis equipment and methodology were fully established). The patients managed with gait analysis had a lower prevalence of surgery at all ages as well as a lower rate of multiple surgeries, suggesting that surgeries were delayed or avoided when gait analysis was included in the patient management protocol.

Finally, one case-control study matched 10 children with cerebral palsy who had surgery in accordance with gait analysis recommendations to 10 children who had the same surgeries recommended but no surgery done.¹² The children who were operated on as recommended by gait analysis had a significantly higher percentage of patients with positive outcomes based on surgery-specific kinematic criteria (44% vs. 26%, p<.0001), with an odds ratio for positive outcome of 3.7 (95% confidence interval: 2.0-7.0). Thus, the likelihood of a positive outcome was significantly greater when surgery was performed as recommended by gait analysis.

Cost effectiveness
Little research has been done on the cost effectiveness of clinical gait analysis. Some consider the cost of the test ($500 to $2500) to be high. However, the cost is relatively modest compared with other medical services received by the typical gait analysis patient. The cost of a gait analysis test can be comparable to that of a pair of ankle-foot orthoses, which many patients receive annually. It is much less than ongoing physical therapy and, certainly, surgery. In addition, gait analysis may result in surgery being delayed or avoided, thus reducing or eliminating those costs.

Proponents of gait analysis assert that the primary benefit of gait analysis is that it allows for more comprehensive and appropriate surgical planning in which all necessary corrections are performed simultaneously.^19,20 This should reduce the need for additional surgeries and lower costs by avoiding surgeries staged over time. One simple study has identified the potential cost savings of single event, multilevel surgery compared with staged surgery.²¹ This study showed that common combinations of surgeries are much more expensive when they are performed in a staged manner. The average billable cost per patient for the nine most common surgical combinations is $26,234 for single event multilevel surgery, compared with $46,268 for staged surgery in which the same procedures are performed one or two at a time over multiple surgical sessions, as is common without gait analysis. Thus, by enabling single event multilevel surgery, gait analysis may reduce surgical costs.

We have recently completed a large retrospective study comparing the costs and amount of surgery experienced by children with cerebral palsy who had gait analysis before surgery (n=313) and those who had surgery without gait analysis (n=149).²² Patients in the gait analysis group had more procedures (5.8 vs. 4.2, p<0.001) and higher costs ($43,006 vs. $35,215, p<0.001) during the index surgery, but less subsequent surgery. A higher percentage of patients went on to additional surgery in the group that did not have gait analysis (32% vs. 11%, p<0.001), with more additional surgeries per person-year (0.3 vs. 0.1, p<0.001) resulting in higher additional costs ($3,009/person-year vs. $916/person-year, p<0.001). The total number of procedures (2.6 vs. 2.3, p=0.22) and costs ($20,448 vs. $19,535, p=0.84) per person-year did not differ significantly between the two groups. Thus, without increasing costs, there was a benefit of gait analysis in terms of a reduced rate of additional surgery, which would result in less disruption to the lives of the patients and their families.

Summary
The impact of gait analysis on treatment decision-making is well established through multiple comparative studies and a recent randomized controlled trial. Gait analysis has two primary effects on decision-making: changing decisions when the gait analysis results disagree with the original treatment plan and reinforcing decisions when the gait analysis results agree with the original plan. Gait analysis influences both the physician’s diagnostic thinking and, ultimately, the treatment received by the patient.

The effect of gait analysis on patient outcomes is less well established in the absence of a randomized controlled trial. However, multiple cohort comparisons and a case-control study strongly suggest that gait and functional outcomes are improved when treatment follows gait analysis recommendations. Finally, gait analysis facilitates single event, multilevel surgery in which more procedures are performed in a single surgical session, reducing the incidence of additional surgery. This benefit is achieved without increasing costs and may potentially reduce costs if the same procedures are performed simultaneously during a single surgery instead of being staged over time.

Tishya A. L. Wren, PhD, is an assistant professor of research orthopaedics, radiology, and biomedical engineering at Childrens Hospital Los Angeles and the University of Southern California, Los Angeles, CA.

Carole A. Tucker, PT, PhD, PCS, is an associate professor of physical therapy and electrical engineering at Temple University, Philadelphia, PA.

Robert M. Kay, MD, is an associate professor of orthopaedics at Childrens Hospital Los Angeles and the University of Southern California, Los Angeles, CA.

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