The Validity of Motion Capture Analysis System against the Gold Standard Long-Standing Radiography in the Measurement of Lower Extremity Alignment

Abstract

Motion capture analysis (MCA) has the advantage of providing a static and dynamic leg axis analysis without radiation. Nevertheless, there is a lack of evidence regarding the accuracy of this technique. To test whether mechanical femorotibial axis angle (MAA) measurement recorded with a non-invasive MCA system is equal to the gold standard static long-standing full-leg radiographs (LSX) and if the degree of malalignment or other parameters (BMI, body mass, height, age) influence the accuracy, a total of 102 consecutive patients were examined using LSX and MCA. Static as well as all gait motion phases at 3 km/h were analyzed regarding the difference between the two angles. There was no statistical difference for MAA between LSX (MAArad) and MCA (MAAstat) (p = 0.091). There was a strong correlation (rs = 0.858, p < 0.001) between the two methods. The highest accuracy was detected for values of standing MCA. Also, the gait MCA values showed strong correlation with LSX but weaker correlation compared to standing MCA (initial swing rs = 0.549; terminal stance rs = 0.815; p < 0.001). BMI, body mass, and height did not influence the accuracy of MCA. MCA enables frontal alignment analysis with high accuracy and without the side effect of radiation.

Influence of leg axis alignment on MRI T2* mapping of the knee in young professional soccer players

“…Determination of the leg axis was performed as previously described using the DIERS formetric 4D (DIERS international, Schlangenbad, Germany) motion analysis system for each leg of the participants [ 15 ]. This system provides two-dimensional video documentation of leg axis geometry in the frontal plane from a posterior view under static and dynamic conditions.…”

“…This system provides two-dimensional video documentation of leg axis geometry in the frontal plane from a posterior view under static and dynamic conditions. Its accuracy for static as well as dynamic measurements was recently validated by Ossendorf et al in comparison to long-standing-leg radiography [ 15 ]. According to the manufacturers´ instructions five tracking skin markers were placed on defined anatomic landmarks of each leg.…”

“…1 ). Data recording, processing, and export were performed with a system-exclusive software (DICAM 3, DIERS International GmbH, Schlangenbad, Germany) [ 15 ]. Knee angles of < 180° (negative values) indicate valgus alignment and angles of > 180° indicate varus alignment (positive values) [ 15 , 21 ].…”

“…Data recording, processing, and export were performed with a system-exclusive software (DICAM 3, DIERS International GmbH, Schlangenbad, Germany) [ 15 ]. Knee angles of < 180° (negative values) indicate valgus alignment and angles of > 180° indicate varus alignment (positive values) [ 15 , 21 ]. Static measurements were carried out with the patient standing in upright, neutral position, full weight bearing and barefooted, wearing only underwear (Fig.…”

“…Radiation-free measurement methods of the leg axis alignment include the caliper method, long-arm goniometer as well as newer gait analysis systems allowing not only evaluation of static but of dynamic limb angles and loads as well [ 11 – 14 ]. Recently Ossendorf et al reported a high accuracy for a two-dimensional motion capture analysis system by demonstrating strong correlations between full-length radiography and said system under static and dynamic conditions [ 15 ].…”