Accuracy of manual vs. motorized trapezium reaming during trapeziometacarpal prosthetic arthroplasty

We compared accuracy of hand and motorized reaming for trapezial cavity preparation in thumb trapeziometacarpal ball-and-socket arthroplasty. A cannulated 9 mm conical reamer (Touch, KeriMedical, Geneva, Switzerland) was used to create cavities in synthetic polyurethane foam blocks of normal and osteoporotic density across six operators (three experienced trapeziometacarpal arthroplasty surgeons and three novices). In this way, 626 cavities were created and analysed by micro-CT scanning to assess diameter, shape ratio, rugosity, and depth, with the data subsequently modelled using mixed-effects regression. Motorized reaming produced significantly smaller, rounder, and smoother cavities than reaming by hand and this effect was most pronounced in dense bone. Operator skill had a modest and inconsistent effect on most outcomes, but novices tend to ream shallower when using motorized reaming compared to manual reaming. This information can be useful to improve primary cup stability in thumb trapeziometacarpal total joint arthroplasty and to guide surgeons in their learning curve.