In total hip arthroplasty, steep cup inclination should be avoided because it increases the risk of edge loading. Pelvic posterior tilt should be carefully monitored because it increases cup inclination and anteversion, leading to edge loading or impingement. The authors evaluated how much the pelvic tilt angle changes from the supine position referenced in planning for cup orientation preoperatively to the standing position 1 year after total hip arthroplasty (Δref). The pelvic tilt angle was measured in 124 patients who underwent total hip arthroplasty due to osteoarthritis, and the mean Δref was -9.5°±5.3° (range, -23° to 5°). Preoperative compression fractures, spondylolisthesis, and disk-space narrowing were predictive of increased pelvic posterior tilt after total hip arthroplasty. The authors mathematically calculated how much change in pelvic posterior tilt was clinically possible with the original cup alignment, which ranged from 40° to 45° of radiographic inclination and 0° to 30° radiographic anteversion to more than 50° of inclination. Even if the maximum posterior tilt (23°) occurred, no edge loading would occur in almost half of those original cups. Surgeons should aim for 40° of inclination. When the original cup inclination was 40°, edge loading was prevented. Edge loading caused by steep cup inclination can be prevented by adjusting the cup orientation to account for predicted pelvic tilting, but spinal alignment must also be considered because lumbar kyphosis can increase postoperative pelvic posterior tilt.

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There is no clear consensus about the best management of intra-articular distal ulnar fractures associated with distal radial fractures in older adults. We describe a treatment wherein the distal radial fractures were securely fixed with a palmar plate, leaving the associated ulnar fractures unfixed. The wrists of 14 patients with a mean age of 74 years were reviewed at an average of 18 months after surgery. The results were excellent in 11 cases and good in three, according to the modified Gartland and Werley score. All fracture sites displayed union, and there was no instability of the distal radioulnar joint. A widening of the distal radioulnar joint space was present in one wrist. Angular deformity of the distal ulnar metaphysis was seen in five wrists. This treatment could be an alternative to open reduction with internal fixation for intra-articular distal ulnar fractures in older adults.

A computed tomography (CT)-based navigation system is one of the support tools to place implant with appropriate alignment and position in total hip arthroplasty (THA). To determine whether the higher performance of the navigation would further improve the accuracy of implant placement in the clinical setting, we retrospectively compared the navigation accuracy of two different versions of a navigation system. The newer version of the navigation system had an upgraded optical sensor with superior positional accuracy. Navigation accuracy, defined as differences between postoperative measurements on CT images and intraoperative records on the navigation system, of 49 THAs performed with the newer version of the navigation system was compared with that of 49 THAs performed with the older version. With the newer version, the mean absolute accuracy (95% limits of agreement) of implant alignment was 1.2° (± 3.3°) for cup inclination, 1.0° (± 2.4°) for cup anteversion, 2.0° (± 4.9°) for stem anteversion, and 1.1° (± 2.4°) for stem valgus angle. The accuracy of the implant position was 1.5 mm (± 3.1 mm), 1.3 mm (± 3.0 mm), and 1.5 mm (± 3.1 mm) for cup x-, y-, and z-axes, respectively, 1.6 mm (± 3.2 mm), 1.4 mm (± 2.9 mm), and 1.5 mm (± 2.7 mm) for stem x-, y-, and z-axes, respectively, and 2.4 mm (± 4.5 mm) for leg length discrepancy. The values for the newer version were significantly more accurate with less variation compared to those of the older version. With upgraded navigation performance, more accurate implant placement was demonstrated in the clinical setting.