OTA 2006 Posters

OTA 2006 Posters

Scientific Poster #63 Basic Science

The Accuracy and Repeatability of a Novel Gait Analysis Device
Michael J. Gardner, MD (n); Joseph U. Barker, MD (n);
Sherry I. Backus, MA, PT (n); Demetris Demetrakopoulos, BS (n);
David L. Helfet, MD (n); Joseph M. Lane, MD (n); Dean G. Lorich, MD (n);
Hospital for Special Surgery, New York, New York, USA

Purpose: A variety of methods have been used to assess lower extremity function following orthopaedic trauma, including self-reported questionnaires, direct observation, and gait analysis. Gait analysis is particularly useful since it provides objective relevant outcome assessment data, and also can be used to compare different treatments. Formal gait analysis, however, requires specialized equipment, advanced training, and can be costly. A portable microcomputer-based device designed to measure gait parameters has recently been developed (IDEEA [Intelligent Device for Energy Expenditure and Activity], MiniSun LLC, Fresno, CA). This device may be particularly useful to evaluate posttraumatic gait parameters in the office setting, but the precision and accuracy of this device relative to a gait laboratory are unknown. We hypothesized that the IDEEA would be as precise and accurate as gait laboratory foot switches.

Methods: Twelve normal subjects without pre-existing lower extremity pathology were enrolled in the study. Each subject was fitted with the IDEEA device, which consists of a small processor clipped to the subject's belt and 5 surface sensors secured to the body, and simultaneously tested with a gait laboratory foot-switch stride analyzer. For each subject, three 10-meter walking trials were conducted at slow, medium, and fast speeds, which were analyzed with both devices. Parameters evaluated were single-limb support time (SLS), double-limb support time (DLS), swing phase duration (SPD), cycle duration, and cadence. Absolute and percent differences between the devices at the three walking speeds were calculated. Right and left feet were compared for SLS as a percentage of cycle duration to determine the precision of each device. '

Results: For SLS, absolute differences were 0.027 to 0.031 sec for the three speeds. For DLS, differences were 0.029 to 0.033 sec; for SPD, differences ranged from 0.024 to 0.032 sec. Cycle duration differed at slow speeds by 0.044 sec and 3.1%; at medium speeds by 0.040 sec and 3.6%; and at fast speeds by 0.071 sec and 6.7%. Cadence differed at slow speeds by 6.7%, at
medium speeds by 8.0%, and at fast speeds by 9.0%. When comparing right vs. left feet, the differences with the IDEEA and gait laboratory were 0.5% vs. 2.7%, respectively (slow), 1.2% vs. 1.2% (medium), and 0.1% vs. 4.3% (fast), which were not significantly different.

Conclusions: The absolute differences of the timed gait parameters between the two devices were all in the range of 0.03 sec, which is within the resolution of the gait laboratory foot switches (0.04 sec). Furthermore, assuming a 1-sec gait cycle, these differences account for only 3% of the gait cycle, which is also well within the clinical parameters for evaluating and differentiating between treatments. The precision between right and left measurements tended to be better, although not significantly, for the IDEEA at slow and fast speeds, but was at least as good as the foot switches.

Significance: The IDEEA device has an accuracy and precision similar to a standard gait laboratory, and may allow more objective assessment of weight-bearing progress with subsequent implications on fracture healing. This also may allow comparison to the contralateral extremity as an internal control, and facilitate outpatient evaluation of treatment alternatives in different fracture patterns.

If noted, the author indicates something of value received. The codes are identified as a-research or institutional support; b-miscellaneous funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts disclosed, and *disclosure not available at time of printing.

· The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an "off label" use). · · FDA information not available at time of printing.