Biomechanical comparison of nitinol compression staples versus fully threaded lag screws for talonavicular arthrodesis

• Published in: Journal of orthopaedics 2023-03, Vol.37, p.64-68
• Main Authors: Reddy, P.J., Manning, B.T., Bezold, W., Garlapaty, A., Cook, J.L., Schweser, K.
• Format: Article
• Language: English
• Subjects: Arthrodesis; Fusion; Lag screws; Nitinol staples; Original article; Talonavicular
• ISSN: 0972-978X; 0972-978X
• DOI: 10.1016/j.jor.2023.02.010

Talonavicular arthrodesis (TNA) is indicated for treatment of disorders that require immobilization of the hindfoot. Lag screw fixation is considered the reference standard technique for TNA. Despite consistently favorable clinical results using lag screw fixation, it is still associated with higher than desired complication and failure rates. Nitinol compression staples have been used for TNA based on potential advantages over lag screw fixation. However, functional biomechanical data comparing lag screw and nitinol compression staples for TNA are lacking. Therefore, the objective of this study was to compare nitinol compression staples to fully threaded lag screws for use in TNA with respect to their biomechanical properties during functional robotic testing. TNA was performed on cadaveric feet (n = 12; 6 matched pairs) using either two nitinol compression staples (Arthrex, Naples, FL) or two fully threaded lag screws (Arthrex, Naples, FL) in random order, alternating between paired left and right feet. After instrumentation, specimens were mounting in a robotic testing system and loaded at 89 N/sec from 30 N to 445 N for 1 min. Then, continuous compressive load of 445 N was applied while cycling from 30° plantarflexion to 15° dorsiflexion for 10 cycles. Optical tracking markers attached to the talus and navicular bone tracked displacements. Translation data were recorded along the X, Y, Z planes. Rotation data were recorded for roll, pitch, and yaw. Significant (p