Cannulated Bone Bolt® Screw System Versus Standard Cannulated Screw System Fixation for Lateral Compression Type-1 (LC-1) Pelvic Ring Injuries: Multicenter Prospective Observational Study

Lateral Compression type-1 (LC1) fractures of the pelvis represent the most common injury to the pelvic ring, accounting for more than 50% of all pelvic ring injuries. These injuries occur secondary to a lateral compressive force on the pelvic ring causing an internal rotation force coupled with medialization of the impacted hemi-pelvis. Despite their prevalence, treatment algorithms for these injuries remain controversial. When significant deformity exists (>1cm displacement) the preference is typically for operative fixation as this has been listed repeatedly as an indication for surgery. In the setting of a minimally displaced LC1 fractures surgical indications become less clear. Minimally displaced fractures can have instability that is under appreciated on static imaging and can result in displacement with non-operative management. This has prompted many surgeons to treat the minimally displaced fracture more aggressively. Surgical intervention provides the benefit of preventing displacement, improving pain, and potentially progressing post-operative mobility.

Previous work has demonstrated short term benefit to the surgical treatment of these injuries, although the treatment benefits noted have been small. A recent observational study conducted at 16 trauma centers prospectively measured short-term VAS pain scores in 194 patients with unilateral sacral fractures and noted that patients with surgical fixation reported 2.7 points less pain at 24 hours postinjury (p=0.001) and 1.1 points less pain at 3 months as compared to those patients treated without surgery (p=0.02). Subsequent to this, an investigator demonstrated a small improvement in pain and functional outcome for up to 12 months in minimally displaced LC1 fractures with complete sacral injuries that were treated with surgical intervention as compared to those patients managed conservatively.

With this information at hand, the current treatment controversy for these injuries has shifted to determining how to optimize surgical fixation and pelvic stability, improve short-term outcomes such as pain, time to mobilization, discharge disposition, and physical function. Many surgeons now consider the short term benefits of surgical intervention to outweigh the risks of percutaneous pelvic fixation, and are desiring a more structurally reliable way in which surgical management to further improve consistency of patient outcomes. Present data provides little to no guidance as to which type of surgical fixation strategy may prove most beneficial to these patients and few advancements have been made in the technology used to treat pelvic ring injuries over the past several decades.

Standard treatment strategies for operative LC1 injuries includes management with cannulated sacroiliac (SI) or trans-sacral (TS) screws in the posterior pelvic ring with or without anterior pelvic ring fixation. Standard cannulated screw System fixation work reasonably well, but loosening and loss of fixation integrity are not infrequent. New advances in FDA cleared screw designs that offer greater mechanical stability, may give more reliable results from surgical treatment.

Given that improvements have been noted with surgical intervention but current surgical techniques and technology have only offered modest clinical benefits, the next logical step is to determine if new technology such as the Cannulated Bone Bolt® Screw System with proven increase mechanical strength and stiffness can improve post-operative patient outcomes. Given that these injuries represent the most common pelvic ring fractures but do not yet have a ideal and fully reliable treatment pathway, the results of this prospective study could greatly improve care of these patients. A prospective observational design is preferred given a true equipoise for screw design used in the operative treatments for these patients.