Sister, Sister! Siblings With Simultaneous Early Femoral Insufficiency Fractures After Total Knee Arthroplasty

Abstract

Early periprosthetic fractures after total knee arthroplasty are rare but devastating complications which require revision surgery and lead to poor patient satisfaction. We present 2 siblings who underwent primary total knee arthroplasty on the same day and then both presented 2 weeks after surgery with atraumatic periprosthetic femur fractures. The first patient underwent revision for a cemented distal femoral replacement with stemmed tibial fixation. The second patient underwent an isolated femoral component revision with a stemmed femoral component and distal augment. Histological evaluation identified significant peri-implant osteoporosis. The variation in complexity associated with early periprosthetic femoral insufficiency fractures is highlighted by these 2 cases. Surgeons may consider using stemmed femoral components in similar patients if poor distal femoral bone stock is encountered intraoperatively.

Keywords: Atraumatic fracture; Insufficiency fracture; Osteoporotic fracture; Periprosthetic fracture; Revision knee arthroplasty.

Figure 1

Preoperative anteroposterior radiographs of patient #1 (a, b) and patient #2 (c, d) demonstrating osteoporotic bone, varus alignment (6° and 16°, respectively, according to the hip-knee-ankle angle) and unloaded lateral femoral condyles.

Figure 2

Three-week postoperative anteroposterior radiographs of patient #1 (a, b) and patient #2 (c, d). Both knees are in marked valgus. Patient #1 presented with a displaced lateral femoral condyle fracture. Patient #2 presented with a bicondylar fracture, with compression and displacement of the lateral condyle and avulsion of the medial condyle.

Figure 3

(a) Six-month postrevision radiograph of patient #1, who underwent revision for a distal femoral replacement with a rotating hinge, 80 × 15-mm cemented femoral stem, and extra-small tibial component with a 102 × 10-mm press-fit stem. (b) High-magnification image of cancellous bone retrieved from revision surgery. The low trabecular bone area reflects osteoporosis. Areas of hemorrhage and microvesicular and macrovesicular fat in the marrow reflect recent ischemia (50×, H&E).

Figure 4

(a) Six-month postrevision radiograph of patient #2, who underwent an isolated femoral component revision with a size-3 revision femur, a 10-mm lateral distal femoral augment, a 5-mm posterior augment, and a press-fit 15 × 135-mm stem. (b) Low-magnification image of articular cartilage and subchondral bone excised during surgery. The disrupted trabeculae reflect an insufficiency fracture (10×, H&E).