Novel minimally invasive tape suture osteosynthesis for instabilities of the pubic symphysis: a biomechanical study

Abstract

Introduction Open book fractures are challenging injuries oftentimes requiring surgical treatment. The current treatment of choice is symphyseal plating, which requires extensive surgery and entirely limits physiological movement of the symphyseal joint, frequently resulting in implant failure. Therefore, we investigated the biomechanical properties of a semi-rigid implant (modified SpeedBridge™) as a minimally invasive tape suture construct for the treatment of open book fractures and evaluated the superiority of two techniques of implementation: criss-cross vs. triangle technique. Materials and methods Nine synthetic symphyseal joints were dissected creating an open book fracture. The different osteosynthesis methods (plating, modified SpeedBridge™ in criss-cross/triangle technique) were then applied. All constructs underwent horizontal and vertical loading, simulating biomechanical forces while sitting, standing and walking. For statistical analysis, dislocation (mm) and stiffness (N/mm) were calculated. Results Symphyseal plating for the treatment of open book fractures proved to be a rigid osteosynthesis significantly limiting the physiological mobility of the symphyseal joint (dislocation: 0.08 ± 0.01 mm) compared to the tape sutures (dislocation: triangle technique 0.27 ± 0.07 mm, criss-cross technique 0.23 ± 0.05 mm) regarding horizontal tension (p < 0.01). Both modified SpeedBridge™ techniques showed sufficient biomechanical stability without one being superior to the other (p > 0.05 in all directions). Considering vertical loading, no statistical difference was found between all osteosynthesis methods (caudal: p = 0.41; cranial: p = 0.61). Conclusions Symphyseal plating proved to be the osteosynthesis method with the highest rigidity. The modified SpeedBridge™ as a semi-rigid suture construct provided statistically sufficient biomechanical stability while maintaining a minimum of symphyseal movement, consequently allowing ligamental healing of the injured joint without iatrogenic arthrodesis. Furthermore, both the criss-cross and the triangle technique displayed significant biomechanical stability without one method being superior.

The radiographic outcome after plating for pubic symphysis diastasis: does it matter clinically?

“…A rigid fixation of the pubic symphysis restricts the normal physiological movement. Cavalcanti Kußmaul et al performed a biomechanical study, which confirmed that symphyseal plating as a rigid osteosynthesis almost entirely compromised the physiological mobility of the symphyseal joint [ 12 ]. In the long run, physiological micromotion may stress the metalwork of the symphysis, resulting in a gradual increase in the symphyseal space and implant failure, such as screw loosening or plate breakage.…”

“…The goals of treating a symphysis diastasis include an appropriate reduction and a stable fixation to provide pelvic ring stability, which can effectively diminish the pain, and permit early mobility [ 6 – 8 ]. Numerous surgical methods have been described for treating pubic symphysis diastasis, including plating, external fixation, tension band wiring, sutures, and percutaneous fixation [ 6 , 9 – 12 ]. Previous biomechanical studies have indicated that symphysis plating is effective in restoring the anterior ring stability [ 13 ], and it has often been used to treat cases of pubic symphysis diastasis worldwide [ 6 ].…”

How relevant is lumbar bone mineral density for the stability of symphyseal implants? A biomechanical cadaver study

“…Another, potentially biomechanically superior, option could be the insertion of minimally invasive Tape-Suture constructs: these constructs have demonstrated sufficient biomechanical stability while allowing the above-mentioned micromovements of the pubic symphysis as shown by previous studies of our group [ 36 ].…”

Trans-obturator cable fixation of open book pelvic injuries

“…Currently, cranial visualization of the pubic rim and retraction of the bladder remains the favored approach for safety reasons. Beside plating or trans-obturatorial cable fixation other innovative stabilization techniques for the pubic symphysis were described in the past 43 – 45 . Chen et al published an article about 45 patients with pubic disruption, treated using percutaneous screw fixation.…”