Reliability of a novel 3-dimensional computed tomography method for reverse shoulder arthroplasty postoperative...

Area of Science:

• Orthopedic surgery
• Medical imaging
• Biomechanical engineering

Background:

• Reverse shoulder arthroplasty (RSA) success depends on accurate component positioning and fixation.
• Current postoperative analysis relies on plain radiographs or 2D CT, which have limitations.
• Metal artifacts hinder 3D CT evaluation of RSAs.

Purpose of the Study:

• To introduce a new 3D CT method for postoperative RSA evaluation.
• To compare the interobserver reliability of the 3D CT method with conventional 2D methods.

Main Methods:

• 3D CT models of scapula, implant, and screws were reconstructed from preoperative and postoperative scans.
• Postoperative models were aligned to preoperative coordinates to measure glenoid baseplate version and inclination.
• Screw volume within bone was quantified using Boolean intersection.
• Four reviewers assessed reliability using both 3D CT and conventional 2D methods.

Main Results:

• The 3D CT method demonstrated excellent reliability for baseplate inclination (ICC=0.92), version (ICC=0.97), and screw volume in bone (ICC=0.99).
• Conventional 2D methods showed poor reliability (ICC < 0.4) for most measurements.
• Radiographs had poor reliability for inclination (ICC=0.09) and fair for screw percentage (ICC=0.54).

Conclusions:

• The proposed 3D CT method offers superior interobserver reliability for RSA analysis.
• This technique effectively overcomes metal artifact limitations in postoperative CT.
• The 3D CT approach enhances the evaluation of glenoid implant positioning and screw fixation.