A prospective case series for a minimally invasive internal fixation device for anterior pelvic ring fractures

A single centre prospective case series at a single Level 1 Trauma Centre was performed from February 2013 until July 2014. The indication for the use of INFIX (two pedicle screws inserted into supraacetabular bone connected by a cobalt chrome bar subcutaneously) was a fracture that the primary surgeon deemed as an unstable anterior ring fracture, typically with fracture site comminution. Fractures were classified using the Young-Burgess classification. . The INFIX was not used for fixation of pubic symphysis injury. The case series was commenced after a 10 patient learning curve by the primary surgeon. Participants were excluded if there was not a minimum six-month follow up. The primary outcome measures were stability and fracture displacement at time of implant removal (assessed by manual stress of the pelvic ring under anaesthesia) and intra and post-operative complications. Data were collected from the Royal Melbourne Hospital Trauma Registry. Descriptive statistics were used to analyse results. Surgical technique If required, stability of the posterior pelvic ring was achieved prior to application of the INFIX. For application of the INFIX a 3cm vertical or oblique incision was made lateral to the interval between Sartorius and Tensor Fascia Lata (TFL), as per the Smith Petersen or anterior approach to the hip joint. The fascia of TFL was incised and blunt dissection continued to the anterior inferior iliac spine (AIIS) between the belly of TFL and Sartorius, reflecting the fascia medially with Sartorius to protect the Lateral Femoral Cutaneous Nerve (LFCN). A 4.3mm drill was used to open the bony safe corridor for the screws, with an entry point at the AIIS, using fluoroscopy to confirm accurate placement on Judet views of the iliac wing. The drills were exchange for guide wires and the corridors tapped to 9 mm over the guide wire. Cannulated Pedicle screws (DePuy SAI Viper, Warsaw, Indiana) (10mm x 100mm) were inserted, also over the guide wires. Screw position was confirmed with fluoroscopy. The screw head was made to sit such that the connecting bar was subcutaneous and superficial to the fascia of the abdominal wall. A 5.5mm Cobalt Chromium bar was contoured then placed subcutaneously. The rod was connected to the screw heads and locked at one end. Reduction of the anterior pelvic ring injury was achieved by compression or distraction of the rod prior to locking of the remaining screw head.