Study highlights advantages of robot-assisted THA - Academy News at the 2007 AAOS Annual Meeting

Study highlights advantages of robot-assisted THA

By Peter Pollack

Research found no intraoperative fractures and higher functional scores

According to poster exhibit P072, robot-assisted total hip arthroplasty (THA) procedures display some mid-term advantages, when compared to conventional THA. Patients who underwent robot-assisted THA had no intraoperative fractures and scored higher on functional hip scores three years after surgery than patients who had conventional THA.

The benefit of robot-assisted stem implantation in THA has remained controversial, and until now, no clinical reports have been available from the period beyond two years after surgery. In this prospective randomized study, researchers compared the clinical results of 144 consecutive patients who received THA performed by several surgeons at two hospitals. Research focused on the period from 36 months to 66 months post-surgery.

Seventy-three surgeries had been performed using the ROBODOCŪ system and 71 were performed using conventional manual THA. There were no significant differences between the two groups with regard to patient age, gender, height, weight and preoperative clinical scores.

Of those cases, 73 surgeries had been performed using the ROBODOCŪ system and 71 were performed using conventional manual THA. There were no significant differences between the two groups with regard to patient age, gender, height, weight and preoperative clinical scores.

Average surgical time was 11 minutes longer in the robotic milling group (p < 0.05), and there were no statistical differences in intraoperative blood loss, dislocation rate or nerve palsy across the two groups. However, researchers found five intraoperative femoral fissures in the manual group and none in the robotic group.

Three years after surgery, Japanese Orthopaedic Association hip scores measuring pain, range of motion, walking ability and activities of daily living were significantly better among patients in the robotic group (p < 0.01), a fact that carried through to final follow-up (p < 0.05). Finally, although radiographs showed bone ingrowth fixation for all of the stems, researchers found more stress shielding of the proximal femur (Engh’s grade 3 or more) in the hand-rasping group than the robotic group (p < 0.05).

The lead researcher is Nobuo Nakamura, MD, of Osaka, Japan. Additional researchers on the team included Nobuhiko Sugano, MD; Takashi Nishii, MD; Hidenobu Miki, MD; Hideki Yoshikawa, MD; Akihiro Kakimoto, MD; Mitsuyoshi Yamamura, MD, and Daiki Iwana, MD, all of Osaka, Japan. The authors report no conflicts of interest.

Note: The ROBODOCŪ system is not yet approved by the U.S. Food and Drug Administration; clinical trials are ongoing.


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