Flexor Pollicis Longus Tendon Wear Associated With Volar Plating: A Cadaveric Study

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Hand surgery

Background:

• Distal radius fractures often require surgical fixation.
• Volar locking plates are commonly used, but plate prominence can affect adjacent tendons.
• The flexor pollicis longus (FPL) tendon is at risk of iatrogenic injury from volar implants.

Purpose of the Study:

• To evaluate the effect of different volar plate designs on the flexor pollicis longus (FPL) tendon.
• To compare contact pressures, wear patterns, and mechanical properties of the FPL tendon with low-profile volar rim (VR) plates, proximally placed variable-angle locking plates (pVA-LCP), and distally placed variable-angle locking plates (dVA-LCP).

Main Methods:

• Cadaveric specimens (9 pairs) were used to assess plate-tendon interactions.
• Thin-film pressure sensors measured initial contact loads.
• Cyclic loading (10,000 cycles) simulated tendon actuation.
• Tendon wear was graded using stereomicroscopy and a blinded Likert scale.
• Uniaxial tensile testing evaluated tendon mechanical properties.

Main Results:

• Both VR plates and dVA-LCP resulted in increased contact pressure and tendon wear compared to pVA-LCP.
• No significant difference in contact pressure or wear was observed between VR and dVA-LCP groups.
• No significant differences in ultimate failure load, stress, stress relaxation, elastic modulus, or stiffness were found among the groups.

Conclusions:

• Plates positioned on or beyond the volar rim lead to elevated contact pressures and increased tendon wear.
• The proximally placed variable-angle locking plate (pVA-LCP) demonstrated the lowest contact pressure and wear.
• While low-profile plates aid fixation, their potential for FPL tendon irritation necessitates careful consideration and possible removal.