Two case reports of greater trochanter fracture at the site of femoral array placement after robotic-assisted hip replacement in the posterolateral approach.

Background: Total hip arthroplasty (THA) using robotic assistance aims to improve implant positioning and overall outcomes. However, emerging evidence reveals specific complications such as fractures related to temporary pin or screw placements in these procedures. Case Description: We describe two patients (a 74-year-old woman and a 74-year-old man) who underwent robotic-assisted THA (RA-THA) via a posterolateral approach following the MAKO hip protocol [Mako robotic-arm system (Stryker)]. Both had a relatively proximal femoral array screw placement, selected to avoid possible screw-stem interference as per the manufacturer's guidelines. Postoperative radiographs showed no immediate complications, but each patient returned within 2 weeks complaining of hip pain and difficulty ambulating in the absence of significant trauma. Imaging revealed trochanteric fractures originating through the prior pin or screw tract. One patient was treated conservatively; the other required two surgical interventions, complicated by periprosthetic joint infection. At their most recent follow-ups, both patients reported limping gait related to gluteus medius insufficiency but no persistent pain. Conclusions: These cases highlight greater trochanter fractures as a complication related to femoral array screw placement in RA-THA. Our experiences suggest that current guidelines on "safe zones" for array fixation may require refinement to account for patient-specific bone structure. Additional biomechanical research is needed to identify optimal pin placement and minimize postoperative fractures.