A unique cause of Gamma 3 cut-out: A case report and literature review

Abstract

Gamma 3 nail is a wide spread intramedullary device for fixation of per trochanteric fractures. Cut out of the lag screw is the most common complication of this implant. We present a 62-year-old female patient, who underwent a total hip arthroplasty following cut out of a Gamma 3 nail in the femoral neck. The cause of the cut out in our case is actually unique. Our intraoperative findings accompanied with the radiographic evaluation argue that the malposition of the set screw was the cause of failure, due to the rotational instability of femoral head-lag screw unit. We present this case with detailed description, highlighting the proper use of this specific nail and appose a brief literature review.

Keywords: Cut out failure; Gamma 3 nail; Head-screw rotation; Intertrochanteric fracture; Set screw malposition.

Fig. 1

Initial anteroposterior x-ray of left hip and proximal femur on admission to our institution shows the cranial cut out of the lag screw of the Gamma 3 nail.

Fig. 2

Photograph from the removed lag screw. The red arrow shows the footprint of the malposition of the set screw outside of the grooves (green arrows). Each lag screw has four grooves, while the correct position of the set screw into the grooves allows lateral sliding and prevents rotation.

Fig. 3

Anteroposterior postoperative x-ray of left hip and proximal femur demonstrates the total hip arthroplasty (cemented femoral stem and an acetabular Müller reinforcement ring) after the removal of the Gamma 3 nail.

Fig. 4

a. Anteroposterior x-ray of left hip and proximal femur demonstrates the initial intertrochanteric fracture of AO type 31 A1.1, a fracture type which traditionally has been considered as rotationally unstable, b. Anteroposterior x-ray of left hip and proximal femur after Gamma 3 nail implantation demonstrates good reduction of the fracture, a low-near to calcar lag screw position, while the H΄/Η ratio is 3.25.

Fig. 5

a. Postoperative anteroposterior x-ray of left hip and proximal femur at 25 days follow up demonstrates more cranial position of the lag screw without any lytic defect behind, while the H΄/H is now 0.65. The grey arrow shows the calcar to the opposite side. All these findings are indicative of the 180° rotation of femoral head-lag screw unit. b. Anteroposterior x-ray of left hip and proximal femur on admission to our institution shows the cranial cut out of the lag screw. After the intraoperative findings, we can now conclude that the grey arrow shows the upside-down calcar, while the green arrow shows the lytic defect from the initial placement of the lag screw, close to the calcar.