Failure of Screw/Shell Interface in the Trident II Acetabular System in Total Hip Arthroplasty

Abstract

We report a case series of 2 patients with screw/shell interface failure in the Stryker Trident II Acetabular System. Both failures consisted of screw penetration through the Trident II acetabular shell. One failure was observed postoperatively after a revision from a cephalomedullary nail to a total hip arthroplasty while the other was observed intraoperatively during a primary total hip arthroplasty. Both component failures were managed conservatively with weight-bearing as tolerated and radiographic monitoring. These are the first reported cup/screw failures of the Stryker Trident II system and should raise awareness of the potential complication and implant design flaw. When placing acetabular screws, we recommend obtaining intraoperative orthogonal screw radiographs that are tangential to the shell surface to assess for screw/shell failure.

Keywords: Arthroplasty; Complication; Hip; Orthopedics.

Figure 1

Initial anterior-posterior radiograph of the right hip (a) upon patient arrival in the emergency department demonstrating an intertrochanteric fracture of the right hip. An interoperative c-arm radiograph (b) demonstrates fixation of the right intertrochanteric fracture with a short cephalomedullary nail. Follow-up anterior-posterior radiograph of the right hip (c) 2 months after the initial surgery demonstrates failure of the cephalomedullary nail with screw cutout and penetration into the acetabulum.

Figure 2

Postoperative anterior-posterior (a) and frog-leg (b) radiographs of the right hip after revision from a failed cephalomedullary nail to total hip arthroplasty. Of note, the failed acetabular screw could not be visualized on these views because orthogonal views of the acetabular cup were not obtained.

Figure 3

Two-week postoperative anterior-posterior (a) and cross-table lateral (b) radiographs of the right hip after revision from a failed cephalomedullary nail to total hip arthroplasty. On the cross-table lateral view, there is evidence of failure in 1 of the acetabular screws (red box); (c) magnified image.

Figure 4

Four-month postoperative anterior-posterior (a) and cross-table lateral (b) radiographs of the right hip. There has been no interval change in the position of the failed acetabular screw (c) seen previously at postoperative week 2 (Fig. 3).

Figure 5

Preoperative anterior-posterior radiograph (a) demonstrating bilateral hip osteoarthritis, with the right hip showing more severe cartilage loss and subchondral sclerosis than the right hip. Intraoperative anterior-posterior radiograph (b) of the left hip with acetabular cup and retractors in place with failure of the acetabular screw (red arrow).

Figure 6

Four-week postoperative anterior-posterior (a) and cross-table lateral (b) radiographs of the right hip after left total hip arthroplasty. On the anterior-posterior view, there is evidence of failure in one of the acetabular screws (red box); (c) magnified image.

Figure 7

Four-month postoperative anterior-posterior (a) and cross-table lateral (b) radiographs of the right hip. There has been no interval change in position of the failed acetabular screw (c) seen previously at postoperative week 4 (Fig. 6).

Figure 8

Schematic of the ideal angle to image acetabular screws and detect potential failure. The x-ray tube (black camera) and detector should be aligned tangential to the acetabular cup surface at the site of the screw. An additional orthogonal view should be acquired.

Figure 9

Rendering of the Stryker Trident II Acetabular System demonstrating the solid core screw hole profile. The recessed screw holes and low-profile hex screws enable up to 37 degrees of screw angulation and minimize the risk of interference with the liner bearing. However, the lower profile design may also contribute to the acetabular screw failure [9].