Axial loading cross screw fixation for the Austin bunionectomy.

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Podiatric Surgery

Background:

• The Austin procedure is a common osteotomy for correcting hallux abductovalgus.
• V-type configurations offer stability but can lead to capital fragment rotation or displacement.

Purpose of the Study:

• To evaluate the biomechanical stability of the Austin osteotomy with a novel double screw fixation technique.
• To compare the stability of single dorsal screw fixation versus combined dorsal and axial loading screw fixation.

Main Methods:

• A biomechanical comparison was performed on 10 Sawbones® metatarsals using an Instron compression device.
• Five metatarsals underwent single dorsal screw fixation.
• Five metatarsals received double screw fixation (dorsal and axial loading screws).

Main Results:

• 100% of single dorsal screw fixation osteotomies failed under compression (average peak load: 205 N).
• Four out of five double screw fixation osteotomies (with axial loading screw) did not fail.
• The axial loading screw, in a crossing orientation, resisted ground reactive forces and provided enhanced fixation.

Conclusions:

• The addition of an axial loading screw significantly increases the stability of the Austin osteotomy.
• This technique reduces the likelihood of capital fragment displacement during hallux abductovalgus surgical repair.
• Cross screw orientation with axial loading enhances mechanical integrity compared to single screw fixation.