gms | German Medical Science

Objectives: Due to the anatomic structure of the pelvis, free-hand placement of screws in acetabular fracture management can be difficult. Infra-acetabular screw fixation increases acetabular stability by distal fixation of the cup. Aim of this cadaveric study is to investigate if a plate-referenced drill guide can provide save placement of an infra-acetabular screw over a pre-contoured supra-pectineal quadrilateral buttress plate (SQBP).

Methods: We constructed a drill-guide for an infra-acetabular screw based on the surface of an anatomically pre-contoured SQBP. A total of 12 adult cadaveric acetabularspecimens were used for drill-guide assisted placement of the infra-acetabular screw.

The drill-guide contains a radiopaque spiral to allow longitudinal fine adjustment of the SQBP along the pelvic brim to assure correct position of the plate-drill-guide construct in relation to the Koehler's teardrop. After screw placement, we conducted a computed tomography (CT) scan of all specimens to assess the actual position of the screw in relation of the infra-acetabular corridor and the acetabular joint surface (Figure 1 [Fig. 1]).

Results and Conclusion: The position of the screw was within the infra-acetabular corridor in all cases. We did not see any intra-articular or intra-pelvic screw penetration. The mean distance of the centerline of the screw to the medial border of the infra-acetabular corridor was 3.35 mm. The secure distance to the virtual surface of the femoral head to was 7.3 mm.

A plate-referenced drill guide can provide safe placement of an infra-acetabular screw for treatment of acetabular fractures. Radiographic fine adjustment is necessary to access the optimal entry point.