Abstract
Previous studies describing drill trajectory for single incision distal biceps tendon repair suggest aiming ulnar and distal (Lo et al). This suggests that the starting point of the drill would be anterior and radial to the anatomic insertion of the distal biceps tendon. Restoration of the anatomic footprint may be important for restoration of normal strength, especially as full supination is approached.
To determine the safest drill trajectory for preventing injury to the posterior interosseous nerve (PIN) when repairing the distal biceps tendon to the ANATOMIC footprint through a single-incision anterior approach utilising cortical button fixation.
Through an anterior approach in ten cadaveric specimens, three drill holes were made in the radial tuberosity from the centre of the anatomic footprint with the forearm fully supinated. Holes were made in a 30º distal, transverse and 30º proximal direction. Each hole was made by angling the trajectory from an anterior to posterior and ulnar to radial direction leaving adequate bone on the ulnar side to accommodate an eight-millimetre tunnel. Proximity of each drill trajectory to the PIN was determined by making a second incision on the dorsum of the proximal forearm. A K-wire was passed through each hole and the distance between the PIN and K-wire measured for each trajectory.
The PIN was closest to the trajectory K-wires drilled 30° distally (mean distance 5.4 mm), contacting the K-wire in three cases. The transverse drill trajectory resulted in contact with the PIN in one case (mean distance 7.6 mm). The proximal drill trajectory appeared safest with no PIN contact (mean distance 13.3 mm). This was statistically significant with a Friedman statistic of 15.05 (p value of 0.00054).
When drilling from the anatomic footprint of the distal biceps tendon the PIN is furthest from a drill trajectory aimed proximally. The drill is aimed radially to minimise blowing out the ulnar cortex of the radius.
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