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

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.

Calculation and correction of secondary translation deformities and secondary length deformities.

External fixation correction of angular deformities leads to secondary translation deformities when occurring around an axis located proximal or distal to the center of rotation of angulation (CORA); secondary length deformities result when correction occurs around an axis concave or convex to the CORA. With circular fixation, the hinge axis can be matched to the CORA. With monolateral fixation, the level of the hinge/angulator is not easily controlled. Axis of correction of angulation can be plotted graphically and secondary deformities calculated trigonometrically. Location of the hinge/angulator can be accurately planned and adjustments incorporated to compensate for expected secondary deformities.

The role of navigation in high tibial osteotomy: a study of 50 patients.

From October 1, 2007, to October 10, 2008, we performed 50 navigated high tibial osteotomies (medial opening wedge). The mean age of the patients was 46.58 years (range, 16-70). Twenty-three osteotomies were performed in women and 27 in men. Two patients received osteotomies on both sites. Average malalignment was 6.4 degrees varus (range, 3 degrees -10.8 degrees ). Sixteen osteotomies were performed on the right side and 34 on the left side. Detailed preoperative planning was performed using the digital MediCad (Hectec GmbH, Niederviehbach, Germany) program based on the malalignment test. Navigation data were compared using full weight-bearing and intraoperative radiographs. Navigation was shown to be an excellent device for intraoperative control of the amount of correction achieved and offers additional information regarding the lateral plain, ligaments, flexion and extension.