Abstract
Due to the complex anatomical shape of the pelvis, screw placement can be challenging in acetabular fracture surgery. This study aims to assess the accuracy of screw placement using patient-specific surgical drilling guides applied to pre-contoured conventional implants in acetabular fracture surgery. CT scans were made of four human cadavers to create 3D models of each (unfractured) pelvis. Implants were pre-contoured on 3D printed pelvic models and optically scanned. Following virtual preoperative planning, surgical drilling guides were designed to fit on top of the implant and were 3D printed. The differences between the pre-planned and actual screw directions (degrees) and screw entry points (mm) were assessed from the pre- and postoperative CT-scans. The median difference between the planned and actual screw direction was 5.9° (IQR: 4–8°) for the in-plate screws and 7.6° (IQR: 6–10°) for the infra-acetabular and column screws. The median entry point differences were 3.6 (IQR: 2–5) mm for the in-plate screws and 2.6 (IQR: 2–3) mm for the infra-acetabular and column screws. No screws penetrated into the hip joint or caused soft tissue injuries. Three-dimensional preoperative planning in combination with surgical guides that envelope pre-contoured conventional implants result in accurate screw placement during acetabular fracture surgery.
Highlights
The implants currently used in acetabular fracture surgery often require multiple bending and contouring manoeuvres intraoperatively, which may result in malpositioning, suboptimal fitting, longer operation time, and therewith increased risk of infection [1]
The personalized surgical drilling guides translated the virtual planning accurately to the surgical procedure by helping the surgeon steer the screws in the pre-planned direction, with only a median difference in screw direction of 6.1 degrees and a median difference in screw entry point of 3.4 mm between the planning and the actual operative result
Surgical guides have only been used in patients in combination with patient-specific implants so far by our group, which resulted in an
Summary
Besides the in-plate screws, some additional infra-acetabular (Pohlemann screw [3]) and column screws might be required to increase the fixation strength [2,4,5,6,7,8,9,10]. Those screws can be difficult to aim due to narrow bone corridors, differences in pelvic geometry between individuals, soft tissue hindrances, a steep slope at the entry point, and difficulties in verifying the screw positions using fluoroscopy [2,6,7,8,9,11]
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