Does difference in stem design affect accuracy of stem alignment in total hip arthroplasty with a CT-based navigation system?

The efficacy of a computed tomography (CT)-based navigation system to accurately position the stem for intended alignment is unclear. In addition, the influence of stem design on the accuracy of insertion is unknown. We therefore retrospectively compared the accuracy and precision for the intended alignment of two different designs of femoral stem which were implanted with or without the navigation system.

Effect of improved navigation performance on the accuracy of implant placement in total hip arthroplasty with a CT-based navigation system.

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.

Effects of coordinate-system construction methods on postoperative computed tomography evaluation of implant orientation after total hip arthroplasty.

Objective: In total hip arthroplasty, it is important to assess postoperative implant orientation. The computed tomography-based (CT-based) three-dimensional (3D) templating method using 3D preoperative planning software is generally recommended. In this method, postoperative implant orientation within a bony coordinate system can be measured by overlaying a 3D computerized model of the implant on a real postoperative CT image of the implant.

Risk of edge-loading and prosthesis impingement due to posterior pelvic tilting after total hip arthroplasty.

Background: Proper implant orientation is essential for avoiding edge-loading and prosthesis impingement in total hip arthroplasty. Although cup orientation is affected by a change in pelvic tilt after surgery, it has been unclear whether surgeons can prevent impingement and edge-loading by proper positioning by taking into account any change in pelvic alignment associated with alteration of hip range of motion.

Methods: We simulated implant orientation without edge-loading and prosthesis impingement, even with a change in pelvic tilt and associated change in hip range of motion after surgery, by collision detection using implant models created with computer-aided design.

Factors predicting change in pelvic posterior tilt after THA.

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).

Anatomical hip range of motion after implantation during total hip arthroplasty with a large change in pelvic inclination.

The supine functional pelvic plane is the recommended reference pelvic plane for acetabular cup planning in navigation-assisted total hip arthroplasty. However, it is unclear whether it can be used in patients with a large preoperative positional change in pelvic inclination (PC) from the supine to the standing position because it is unknown whether these patients have a different hip range of motion (ROM). We measured the anatomical hip ROM after implantation by computed tomography-based navigation in 91 patients and found it to be similar between those with a small PC (<10°) and those with a large PC (≥10°).

[Successful completion of left total hip arthroplasty by inhibitor neutralization therapy in a hemophilia B patient with high responding inhibitor].

Major surgery in hemophilia patients has been facilitated by the development of coagulation concentrates. However, it is still difficult to manage bleeding during major surgery in patients with inhibitors to FVIII/IX. In addition, there have been few reports of major surgery in hemophilia B with high responding inhibitors.