Three-dimensional rotation of the scapula during functional movements: an in vivo study in healthy volunteers.

The goal of this study was to measure 3-dimensional shoulder motion by use of a direct invasive technique during 4 different arm movements in healthy volunteers. Eight subjects with healthy shoulders were recruited. Optoelectronic marker carriers (ie, infrared light-emitting diodes) were mounted on bone pins, which were inserted into the lateral scapular spine.

The effect of shoulder arthroplasty on humeral strength: an in vitro biomechanical investigation.

Background: Periprosthetic humeral fractures are a serious complication of shoulder arthroplasty. While adequate reaming of the canal and insertion of an oversized implant optimizes fit, such maneuvers also weaken the bone and predispose it to fracture.

Methods: The impact of the humeral arthroplasty was assessed in vitro on human cadaveric specimens.

Improved RSA accuracy with DLT and balanced calibration marker distributions with an assessment of initial-calibration.

Roentgen stereophotogrammetric analysis (RSA) has been used for over 25 years for accurate micromotion measurement in a wide variety of orthopaedic applications. This study investigated two possible improvements to the method. First, direct linear transformation (DLT) was compared to the traditional RSA reconstruction algorithm.