This preliminary study demonstrated the clinical feasibility of T2 assessment of hip cartilage using 3T MR imaging. T2 mapping classification may enable the early detection of osteoarthritic degeneration and the detection of developmental disorders of cartilage matrix in patients with hip dysplasia.

Objective: The objectives of this study were to evaluate the accuracy of computed tomography (CT)-based navigation and to investigate whether the level of surgeon experience affects the accuracy of cup positioning under navigation. Methods: This study investigated 117 hips in 103 patients who underwent primary total hip arthroplasty (THA) by 7 surgeons using a CT-based navigation system. Pre-and postoperative CT images were matched using a volume registration technique. Postoperative cup angles and positions were then measured using the same pelvic coordinates, and results were compared for experienced and inexperienced surgeons. Results: The mean absolute error of the cup angle was 1.8 AE 1.6 for inclination and 1.2 AE 1.1 for anteversion. The mean absolute errors of cup position were 1.9 AE 1.5 mm, 1.4 AE 1.2 mm, and 1.9 AE 1.3 mm on the x-, y-and z-axes, respectively. No significant differences in accuracy were identified between experienced and inexperienced surgeons. Conclusions:The absolute spatial error of cup position was 2 mm for each axis, and the angle error was 2 for the angles of inclination and anteversion. This navigation system could therefore help surgeons perform accurate cup placement irrespective of the surgeon's level of experience.

ABSTRACT:The ROBODOC system has provided better fit and fill of the stem and less destruction of the bony architecture than with manual surgery. These benefits might affect femoral periprosthetic bone remodeling. We evaluated the effects of robotic milling in cementless total hip arthroplasty (THA) in a longitudinal 24-month follow-up study using dual energy X-ray absorptiometry (DEXA) and plain radiographs of 29 patients (31 hips) after ROBODOC THA and 24 patients (27 hips) after manual THA with the same stem design. To minimize the influence of other factors on bone remodeling, only female osteoarthritis patients, who had no drugs that might affect bone metabolism were enrolled. Significantly less bone loss occurred at the proximal periprosthetic areas in the ROBODOC group. In zone 1, the decrease was 15.5 versus 29.9% using conventional rasping; in zone 7, the loss was 17.0% with ROBODOC compared to 30.5% with conventional rasping (p < 0.05). On radiographs, endosteal spot welds in the proximal medial portion were more pronounced in the ROBODOC group (48 vs. 11% in the conventional group, p < 0.05). Our results suggest that robotic milling is effective in facilitating proximal load transfer around the femoral component and minimizing bone loss after cementless THA. ß

Malalignment of the cup in total hip arthroplasty (THA) increases the risks of postoperative complications such as neck cup impingement, dislocation, and wear. We asked whether a tailor-made surgical guide based on CT images would reduce the incidence of outliers beyond 10°from preoperatively planned alignment of the cup compared with those without the surgical guide. We prospectively followed 38 patients (38 hips, Group 1) having primary THA with the conventional technique and 31 patients (31 hips, Group 2) using the surgical guide. We designed the guide for Group 2 based on CT images and fixed it to the acetabular edge with a Kirschner wire to indicate the planned cup direction. Postoperative CT images showed the guide reduced the number of outliers compared with the conventional method (Group 1, 23.

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