Minimally Invasive Surgery for Anterior Pubic Rami Fractures Under Fluoro-Navigation Using the Medtronic O Arm System and Calcium Phosphate for Internal Fixation

Introduction: The incidence of anterior pubic rami fractures in elderly female patients over the age of 65 has been reported to be 64 %. Osteoporosis plays a role with these fractures, as they are caused by minimal low energy injuries from a fall. Indications for internal fixation of anterior pelvic ring are controversial because of the etiology being low energy trauma and the location being a non-weight bearing surface. In contrast to conventional open pelvic surgery, percutaneous screw fixation has gained popularity in the treatment of pelvic fractures, mainly because of minimal soft tissue damage, less operative blood loss, early surgical intervention, and comfortable mobilization of the patient. The use of calcium phosphate as a form of internal fixation further advances the advantages of minimally invasive surgery for internal fixation with less morbidity by the use of screw fixation. The incorporation of fluoro-navigation is a new surgical technique in orthopedic trauma surgery. (Figure 1) This study is to report our clinical results of fluoro-navigation surgery in anterior pelvic pubic rami fractures using calcium phosphate as the fixation of choice. This is the first report of this method of treatment using a new combination of visualization and internal fixation. Materials and Methods: From April 2018 to December 2019, 30 patients with anterior pubic rami fractures were treated with percutaneous cannulated calcium phosphate delivery under Medtronic O arm (fluoro-navigation) control. There were 5 male and 25 females, with a mean age of 84.6 years (range 80-104) for females and mean age of 90 years (84 – 99) for the 5 males. According to the AO and Orthopedic Trauma Association classification, all were considered lateral compression types of fractures. All patients were operated on when their general medical condition stabilized after emergency management and admission. The pain score on admission was reported as 10/10 in all cases. Plain standard pelvic x-rays were obtained on admission as well as CT scans of the pelvis. All the anterior pubic rami fractures were fixed using percutaneous delivery of calcium phosphate with the Zimmer trocar system by one senior surgeon. The Medtronics O arm fluoro-navigation was used in all cases. The surgeon was familiar with the navigation system and had much experience in the computer-assisted percutaneous placement of the trocars. Results: A total of 30 patients were treated with this new combination of surgical treatment of anterior pubic rami fractures. No screws were inserted or found to be necessary for fracture treatment. Each case used 2 trocars from the kits supplied from Zimmer. One end delivery trocar was directed to the inferior pubic ramus fracture and the second which was a side delivery trocar was used for the superior pubic ramus fracture. A total of 10 cc of calcium phosphate was used in each case, 5 cc per trocar. The position of the trocars were placed using the fluoro-navigation control of the O arm. Once the trocars were properly placed the calcium phosphate was delivered and viewed under flouro control and then again viewed with the spin sequence using the Medtronics O arm. Total patient time in the operating room was 56 minutes; Total surgery time was 26 minutes. Anesthesia in most cases was MAC or light sedation with local skin infiltration using 1% lidocaine. Blood loss during the operation was considered very minimal with derma bond used to cover the percutaneous sites as well as a small band-aid. No superficial or deep infections occurred. No patient sustained recognized neurologic, vascular, or urologic injury because of the percutaneous pubic rami fixation with calcium phosphate. Extravasation of the calcium phosphate from the fracture’s sites did not pose any sequelae with soft tissue injury or with fracture healing. All patients were encouraged to get out of bed and weight bear according to comfort on post-op day 1. All fractures united at the last follow-up. Conclusions: This study presented for the first time two new techniques for the operative treatment of pubic rami fractures of the pelvis. The delivery of calcium phosphate for fracture fixation of pubic rami fractures has been found to be safe, minimally invasive, providing pain relief and stability permitting early mobilization. The addition of intra-operative fluoro- navigation technique makes the fracture treatment an accurate, and rapid method for the treatment of pubic rami fractures. Consistency of the operative procedure and teaching are mandatory for the success of this procedure. The learning curve for most orthopedists should be very short. The outcomes have been shown to benefit patient mobilization, decrease morbidity and decrease hospital stay