Abstract
Background
Few clinical hip score include toe-reach motion after THA (put-on-socks, shoe-ties, nail-cuttingãf»ãf»ãf») Some reports have shown whether THA patients can put on socks or not in daily activity, and not shown how they can do it. The purpose of this study is to investigate real pattern of put-on-socks motion in daily activities after THA, and to evaluate the characteristics of the motion quantitatively.
Materials and Methods
1st step
Reviewing clinical chart, we investigated highly frequent pattern in wearing socks motion that would cause dislocation in ADL in 100 patients with normal lower extremities except for hip more than one year after THA, then, we classified the motion pattern.
2nd step:
Using an optical 3-D motion analysis we measured necessary angles on trunk, hip, knee and ankle in 10 healthy volunteers and 20 THA subjects one month postoperatively, while the volunteers or THA subjects make such frequent patterns of movement based on the 1st step. ALL joint angle was defined as “zero” in static standing position. We also compared the angles in THA subjects with those of the volunteers.
Motion analysis technology with optical sensors is;
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1)
Track 30 infrared reflection sensors on subjects' body surface with infrared camera in the requested motions (MAC3D system, Motion Analysis, USA).
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2)
Collect 3-D coordinates of 30 sensors' positions over time during subjects' motions.
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3)
Calculate joint angle, driving 3-D installed skeletal model combined with motion data collected in 2) on display over time (SIMM, Musculographics).
Results
Resulting from clinical chart, most patients (78%) behave in an individual manner regardless of postoperative guidance for prevention of hip dislocation more than 1 year after THA. High incident pattern of the motion was “Leg raising pattern” (26%), and “Trunk flexion pattern” (23%) (Fig. 1). For above two pattern of the socks-wearing motion, 3-D motion analysis showed that maximum hip flexion angle was 78.7±5.2 degrees for leg raising pattern, 80.4±6.8 degrees for trunk flexion pattern, and they were significantly lower than those of the volunteers. Moreover, it showed that maximum ankle dorsal flexion angle was 13.6±10.5 degrees, 9.5±10.5 degrees respectively and they were significantly larger than those of the volunteers. It was not significant between THA patients and volunteers for maximum trunk and knee joint angle during each motion, respectively (Fig. 2, Fig. 3). Hip angle of abduction/adduction or external/internal rotation was within 15 degrees during each motion.
Discussion
Most reports refer to early postoperative period, and express ability to do the motion, as indicated posture for prevention of hip dislocation. However, current study showed that most patients (78%) behave in an individual manner more than 1 year after THA. During wearing socks motion, in THA group, compared to control group, hip flexion was lower and ankle dorsal flexion was higher, suggesting compensation for the disability of hip joint with the ankle motion one month after THA.
