Efficacy of Robot-Assisted Hip Stem Implantation. A Radiographic Comparison of Matched-Pair Femurs Prepared Manually and with the Robodoc^® System Using an Anatomic Prosthesis

Abstract

The number of robots in operation in the German-speaking orthopaedic community more than doubled last year, reflecting considerable excitement among patients and doctors over the prospects of improving the accuracy of endoprosthesis surgery in both the planning and implantation stages. The purported improvement, however, adds considerable expense to the procedures although little data exist still in many applications to prove its efficacy.

The following study compares pre- and post-operative radiographs of conventionally- and robotically-prepared groups of donor femurs implanted with an anatomic hip stem to quantify their respective preservation of three anatomic parameters– leg length, anterior bow angle, and mediolateral offset. All femurs were planned blindly both with virtual fitting using 3D reconstruction from CT scans and with conventional templates.

Maintenance of leg length as well as anterior bow angle were significantly higher (p<0.05) for the robotically-prepared group than for the manually-prepared group. Maintenance of mediolateral offset, however, was significantly higher for the manually-prepared group, likely due to the common varus implantation experienced with this prosthesis type. Further studies will examine microradiographic slices in the transverse plane to quantify the gap size resulting from the two methods.

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