No abstract

We can use this guide with acceptable accuracy and without consuming an excessive amount of time.

No abstract

We have developed a novel system of four-dimensional motion analysis after total hip arthroplasty (THA) that can aid in preventing dislocation by assessing safe range of motion for patients in several daily activities. This system uses skeletal structure data from CT and motion capture data from an infrared position sensor. A 3-D model reconstructed from CT data is combined with the motion capture data. Using this system, we analyzed hip motion when getting up from and sitting down in a chair or picking up a n object while sitting in a chair in 17 patients (26 hips) who underwent THA. To assess the accuracy of this system's measurements, open MRI was used to evaluate positions of skin markers against bones in five healthy volunteers in various postures. No impingement between bones and/or implants was found in any subjects during any activities. However, mean angle at the point of maximum hip flexion was different for each patient. The open MRI results indicated that average error in hip angle of the present system was within 5" for each static posture. The functional position of the pelvis during daily activities must be taken into account when assessing the real risk of dislocation. The present system enables dynamic analysis involving not only alignment of components and bones of each patient, but also individual differences in characteristics of daily motions. Further investigation using this system can help determine safe ranges of motion for preventing hip dislocation, improving the accuracy of individualized guidance for patients regarding postoperative activities.

Intraoperative pulmonary embolism occurs not only during cemented but also during cementless total hip arthroplasty (THA). We determined whether the ROBODOC femoral milling system can reduce intraoperative pulmonary embolism, by using of transesophageal echocardiography and hemodynamic monitoring. We did a prospective clinical trial with 71 patients (75 hips) who were divided into 2 groups: group 1, 46 patients (50 hips) who underwent cementless THA with preparation of the femoral canal using ROBODOC; group 2, 25 patients (25 hips) who underwent conventional cementless THA surgery in whom separate measurements were made during preparation of the femur, insertion of the stem and relocation of the hip. The incidence of severe embolic events was lower in group 1 than in group 2. Our findings suggest that the ROBODOC femoral milling system may reduce the risk of clinically significant pulmonary embolism during cementless THA.