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1996 Publications

Ultrasound-Based Kinematic Analysis of Gait in Patients Following Anterior Cruciate Ligament (ACL) Autograft Surgeryby Gilbert W. Gleim, Simon Ben-Avi*, Ian J. Kremenic.Nicholas Inst. of Sports Medicine and Athletic Trauma, Lenox Hill Hospital, and *The Cooper Union for Advancement of Science and Art, Albert Nerken School of Engineering, New York, New York, U.S.A. - last modified 2013-02-09 00:00
International Society of Biomechanics, 1996.


INTRODUCTION: Light based 3-D motion analysis requires placement of cameras in two planes. Ultrasound based analysis allows for 3-D analysis with receivers in 1 plane. We have adapted an ultrasound based tracking system (V-scope) to the 3-D study of human gait and report here its ability to detect gait abnormalities in post surgical patients.

METHODS: We have previously described the adaptation of the V-Scope to the study of human gait and have demonstrated its reliability by repeated measurements in 10 normal controls (Kremenic et al, 1995, Trans 2nd Comb ORS). Briefly, three towers placed on a mobile cart next to the treadmill emit infrared light which is detected by small transponders attached to the joints of interest. They emit an ultrasonic "chirp" which is received by the towers. By triangulation, their location in space is known. A custom program provides stick figures, velocities and angles in three planes, averaged over the course of 40 seconds of continous data collection.

In this study we examined 6 controls (C) at a treadmill walking speed of 3.0 mph and compared them to 5 patients (Pts) who were an average of 2 months post ACL reconstruction. The Pts walked at their maximum pace which averaged 2.8 mph (ns, from C). At the time of measurement all Pts had full range of motion measured passively by a physical therapist. We looked at the maximum angles of knee extension/ flexion (EXT/FLEX) during swing, flexion excursion during stance (FLEXEX) and stance excursion (STANEX).

RESULTS: C demonstrated no side to side differences in either the angles mentioned above or the overall shape of their knee angle curves. The left leg of C was arbitrarily chosen for comparison to the affected leg of Pts. FLEX did not differ between Pts and C (59 +/- 5 deg. v. 54 +/- 2 deg.). EXT was significantly less in Pts (-7 +/- 2 deg. v. 2 +/- 1 deg., P=.003). FLEXEX was marginally reduced as well (14 +/- 2 deg. v. 18 +/- 1 deg., p=.07). STANEX was dramatically reduced in Pts (3 +/- 2 deg. v. 12 +/- 1 deg., p=.005). Representative curves from C and Pts are shown in the figure.

CONCLUSIONS: These data demonstrate the ability of ultrasound based kinematic analysis of gait to detect differences in knee motion despite normal passive range of motion assessed independently. The system described allows for 3-D gait analysis on a treadmill with minimum cost and space requirements