Nitinol and First MTP Fusion

First metatarsophalangeal (MTP) joint arthrodesis is traditionally fixed using plates and screws. Nitinol, a superelastic alloy, offers dynamic compression, but its biomechanical performance in MTP fusion is unclear.

To evaluate its effectiveness, a cadaveric study was conducted comparing three different fixation constructs: 

1. Titanium plate with a cross screw (PS)

2. Nitinol staple with a cross screw (NSS)

3. Nitinol hybrid screw with a cross screw (NHS)

Twelve paired specimens underwent cyclic loading (100 cycles ranging from 20–90 N) followed by failure testing.

Key findings

The results demonstrated that both Nitinol-based constructs outperformed the traditional PS construct. Specifically, NSS and NHS showed significantly higher failure loads (196 N and 161 N vs. lower in PS), greater stiffness (33 N/mm and 29 N/mm), less deflection after loading, and reduced gapping at failure.

No significant differences were observed between the two Nitinol groups.

Fixation using Nitinol demonstrated superior biomechanical strength and stability, compared to conventional methods, supporting its potential as an improved option for MTP arthrodesis.