A comparative cadaveric biomechanical analysis of the differences between dynamic external traction devices for PIP joint fracture dislocation.

Abstract

Purpose: No study in the literature compares different external distractors for PIPJ injury. We compared a device described by Suzuki et al and another by Hynes & Giddins in non-injured cadaveric fingers. Main outcome measures were articular space and PIPJ flexion resistance. Methods: Thirty-two Thiel embalmed fingers were used. The elastics based model was performed with 3 and 5 elastics per side (3E and 5E); the 2-pin model used no elastics (2P). Articular distraction of each device was measured using x-ray imaging. The force required to flex the PIP joint to 45˚ and 90˚ in each group was measured with a dynamometer. Main findings: The articular distraction was statistically significant for all groups. The difference in articular distraction was significant in the AP view between groups 3E and 2P, and 5E and 2P. Flexion forces were only significant between group 5E and 2P at 90˚ flexion, but resistance was notably higher in group 2P than in groups 3E and 5E. Group 2P was more difficult to engage and often disengaged in flexion compared to groups 3E and 5E. Conclusion: All devices achieved significant articular distraction (>99% in AP) but optimal distraction has not been clinically determined and may depend on each unique fracture, hence a variable distraction device may be optimal. The 3E and 5E models can be adjusted for distraction by adding the sufficient elastics to reduce individual fractures. The increased resistance to PIP flexion found in the 2P model may limit post-op mobilization, but clinical correlation is needed.

Keywords

• Suzuki frame
• PIP joint fracture
• biomechanical analysis
• cadaveric model
• pin and rubber traction system