Mini-Plating Can Influence Compression Achieved In Long Bone Fracture Fixed With Dynamic Compression Plating (DCP)

Cary Schwartzbach 1,2,4 Ryan Westbrook 1 Lolita Ramsey 1 Ilia Iliev 3 Jihui Li 1
1Orthopaedic Trauma, Inova Fairfax Medical Campus, Falls Church, USA
2Orthopaedic Surgery, Virginia Commonwealth University School of Medicine, Richmond, USA
3Orthopaedic Surgery, Marshall University School of Medicine, Huntington, USA
4Orthopaedic Surgery, Georgetown University School of Medicine, Washington, USA

Introduction: Compression plating is essential for primary healing of long bone fractures. Mini-plates can be used for provisional fixation but may potentially enhance or block the compression at the fracture and influence its healing. The purpose of this study was to investigate whether mini- plates and screw placement (neutral vs. eccentric) interfered with the compression and pressure distribution achieved by plating.

Methods: Transverse fractures were created on 20 synthetic bone specimens, divided into two groups based on screw placement of the mini-plate. In the Compression group, screws were placed eccentrically generating compression. In the Static group, screws were placed neutrally. A DCP was then oriented parallel to the mini-plate, separated by 90 degrees and three screws were tightened on one side. On the other side, screws were eccentrically placed to generate compression. In the control setting, the mini-plate was removed prior to screw compression, whereas in the experimental setting they were left in place. This generated a 2 x 2 matrix of conditions: compression vs. static x experimental vs. control. A Tekscan pressure sensor was placed in the fracture to monitor the compressive force and pressure distribution during sequential screw tightening.

Results: In the Compression group, mini-plate retention (experimental setting) generated higher fracture compression than the control setting, but lower compressive forces (than the control setting) in the Static group. There were no significant differences in compressive forces between the two control settings, but in the experimental setting the Compression group had higher compressive forces. In the Compression group mini- plate significantly increased the contact area compared to those without mini-plate. Pressure peaks occurred close to the compression plate.

Discussion and Conclusion: This study suggested that mini-plate has a significant impact on the fracture compression.