Session VIII - Pelvis
Comparative Radiographic and Clinical Outcome of Two-Hole and Multi-Hole Symphyseal Plating
Purpose: Two-hole and multihole symphyseal plates are biomechanically equivalent for the treatment of symphyseal disruptions. Currently, no definitive recommendation exists for choosing between a two-hole or multihole symphyseal plate. The objective of this analysis is to report on the radiographic and clinical outcome of both plating techniques, specifically examining implant failure, reoperation, and ability to achieve and maintain reduction of the pelvic ring.
Hypothesis: Two-hole plates are superior in that they allow some degree of motion at the pubic symphysis. This may be beneficial for two reasons: (1) it allows physiologic motion of the hemipelvis with ambulation, and (2) it will decrease the hardware failure rate as less stress is borne by the plate/screw construct.
Methods: Inclusion criteria were skeletally mature patients with pelvic disruptions associated with pubic symphysis diastasis requiring open reduction and internal fixation (ORIF). Patients were grouped according to plating techniquegroup THP (two-hole plates) and group MHP (multihole plates). Retrospective chart and radiographic review was performed. Collected data analyzed pelvic ring injury, type of anterior and posterior fixation, quality of postoperative reduction, mode and timing of loss of reduction, implant failure and mode of implant failure, and need for reoperation secondary to implant complication.
Results: 81 patients with an average age of 42 years had complete data. Average follow-up was 14 months. There were 47 patients in the THP group and 34 patients in MHP. 25 patients in THP (53%) and 15 patients in MHP (44%) required posterior ring fixation (SI screw or ORIF of crescent fracture). Implant failure rate was 17 of 47 (36%) in THP and 4 of 34 (12%) in MHP (p<0.05). Failure mode for THP was loosening and backing out of screws, while for MHP it was plate or screw breakage. Reoperation for implant-related complications was 7 of 47 (15%) for THP and 3 of 34 (9%) for MHP. A higher failure rate of the posterior fixation occurred in THP (6%) than MHP (3%). The most notable finding, however, was that loss of reduction or malunion of the pelvic ring was significantly higher in THP (36%) than MHP (6%) (p<0.01). Specifically the two-hole plating technique resulted in a sagittal plane rotational deformity of the affected hemipelvis that could not be controlled by the two-hole plate.
Conclusions: The two-hole symphyseal plating technique resulted in a significantly higher rate of implant failure and, more importantly, a significantly higher rate of pelvic malreduction/malunion. It remains to be determined if this sagittal plane rotational deformity is clinically relevant.
Significance: Based on the findings of this study, we believe that multihole symphyseal plating is a superior construct compared to two-hole plating in that it results in a lower implant failure and pelvic malunion rate.