Original Article
The Effect of Drill Trajectory on Proximity to the Posterior Interosseous Nerve During Cortical Button Distal Biceps Repair

https://doi.org/10.1016/j.arthro.2011.03.084Get rights and content

Purpose

The aim of this study was to evaluate the effect that different drill trajectories across the radius have on the proximity of the drill tip to the posterior interosseous nerve (PIN).

Methods

In 10 cadaveric specimens, we drilled from the bicipital tuberosity across the radius using 4 different trajectories: (1) aiming across the radius at 90° to the longitudinal axis of the radius, (2) distally at 45°, (3) ulnarly, and (4) radially. We measured the distance between the tip of the drill as it exited the dorsal cortex of the radius and the PIN.

Results

Aiming 90° across the radius and aiming ulnarly across the radius resulted in a distance of 11.2 ± 3.2 mm (95% confidence interval [CI], 8.9 to 13.5 mm) and 16.0 ± 3.8 mm (95% CI, 13.3 to 18.7 mm), respectively, between the drill tip and the PIN. Aiming the drill 45° distally and aiming radially resulted in a distance of only 2.0 ± 2.2 mm (95% CI, 0.5 to 3.6 mm) and 4.2 ± 2.2 mm (95% CI, 2.6 to 5.8 mm), respectively. The differences were found to be statistically significant.

Conclusions

On the basis of the results of this anatomic study, when using the cortical button distal biceps repair technique, we recommend drilling across the radius at 90° to its longitudinal axis and aiming from 0° to 30° ulnarly, with the patient's forearm in full supination. This provides an increased margin of safety to prevent injury to the PIN compared with drilling radially or distally.

Clinical Relevance

By avoiding distal and radial drilling, the risks of PIN injury should be minimized during distal biceps tendon repair.

Section snippets

Methods

Ten fresh-frozen unmatched adult cadaveric arms were brought to room temperature. The arms had been harvested at the midhumerus and were intact distally. No visible deformities or evidence of previous surgery was noted in any of the specimens. The gender and side of each specimen were recorded, as well as the length, from the tip of the ulnar styloid to the olecranon process.

The PIN was exposed in each specimen through a longitudinal incision in the proximal dorsal forearm. The PIN was

Results

Of the specimens, 5 were right arms and 5 were left arms. The mean ulnar length was 27.4 cm, with a range of 24.0 to 31.5 cm. Three specimens were female. The mean specimen age was 71.8 years, with a range of 43 to 96 years.

When drilling across the radius using trajectory A, we found that the guide pin exited the dorsal cortex of the radius at a mean of 11.2 ± 3.2 mm (95% confidence interval [CI], 8.9 to 13.5 mm) from the PIN. Drill trajectory B resulted in a mean distance of 2.0 ± 2.2 mm (95%

Discussion

Repair of distal biceps ruptures has been shown to improve subjective and objective outcome measures compared with nonoperative treatment.3, 7, 12 Using a cortical button to repair the biceps to the proximal radius has recently gained popularity. This novel technique, described by Bain et al.,13 has been shown to have several advantages over previously described repair techniques. First, the cortical button repair has consistently shown stronger initial fixation strength compared with

Conclusions

On the basis of the results of this anatomic study, when using the cortical button distal biceps repair technique, we recommend drilling across the radius at 90° to its longitudinal axis and aiming from 0° to 30° ulnarly, with the patient's forearm in full supination. This provides an increased margin of safety to prevent injury to the PIN compared with drilling radially or distally.

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    Statistical support for this publication was made possible by grant UL1 RR024146 from the National Center for Research Resources, a component of the National Institutes of Health (NIH), and NIH Roadmap for Medical Research. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of the National Center for Research Resources or NIH. Information on re-engineering the clinical research enterprise can be obtained from http://nihroadmap.nih.gov/clinicalresearch/overview-translational.asp.

    The author reports no conflict of interest.

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