Single-screw fixation for subtalar joint fusion does not increase nonunion rate

Area of Science:

• Orthopedic surgery
• Foot and Ankle surgery
• Biomechanical engineering

Background:

• Increasing trend towards joint-sparing procedures like isolated subtalar joint (STJ) fusion over triple arthrodesis.
• Controversy exists regarding optimal internal fixation for STJ fusion due to variable union rates (47-100%).
• Potential for motion with single-screw fixation, parallel to the STJ axis, raises concerns about nonunion.

Purpose of the Study:

• To investigate whether single-screw fixation is a predisposing factor for nonunion in isolated STJ arthrodesis.
• To compare nonunion rates between single-screw and two-screw fixation techniques for STJ fusion.
• To evaluate the impact of screw fixation on postoperative complications and revision rates.

Main Methods:

• Retrospective review of 113 isolated STJ arthrodesis procedures.
• Categorization of fusions into single-screw (n=89) and two-screw (n=24) fixation groups.
• Analysis of nonunion rates, hardware removal, and revision surgery incidence over a mean follow-up of 11 months.

Main Results:

• Nonunion occurred in 14.6% of single-screw fusions and 25.0% of two-screw fusions.
• Hardware removal was required in 22.5% of single-screw and 12.5% of two-screw fusions.
• No statistically significant differences were observed in nonunion rates, complication incidence, or revision surgery between the two fixation groups.

Conclusions:

• Single-screw fixation does not appear to predispose subtalar joint fusions to nonunion.
• Comparable rates of nonunion and postoperative complications exist between single and two-screw fixation methods.
• The motion associated with single-screw fixation may not be substantial enough to impede STJ fusion healing.