The currently reviewed study by Rees et al. is a biomechanical study about anterior cervical discectomy and fusion (ACDF) plate screw hole preparation that was published in the North American Spine Society Journal. ACDF is a very common spine procedure for which anterior plates are routinely used. Rees et al interestingly considered one aspect of the plating procedure: how to prepare the pilot hole for the screws. The study compared the commonly used drill versus the less commonly used awl. In making the hole for a screw, a drill removes some bone with the flute of the drill bit, while an awl compresses bone to the side of the hole in preparation for a screw.

Uniformly printed acrylonitrile butadiene styrene filament testing blocks were used for this study. These were based on a high-resolution computed tomography (CT) scan of a normal cervical spine (C5-C6). The blocks were designed to have an inner substance analogous to cancellous bone and a superficial surface analogous to cortical bone. A 1.8 mm central divot was also added to the superficial surface to standardize ACDF plate placement.

ACDF plates (Depuy Synthes Cervical Spine Locking Plates) were aligned to each block, where four pilot holes were made for the plates’ screws. Half (n = 20) used the awl technique, and half (n = 20) used the drill technique. The awl and drill, both with diameters of 3 mm, were marked at depths of 8.5 mm to standardize pilot hole size. ACDF plates with attached cables for pullout testing were then attached to their blocks with four screws (length: 12 mm, core diameter: 2.4 mm, outer diameter: 3.5 mm). The team measured pullout force until the point of hardware failure, defined as the detection of a force 50% or less of the maximum recorded value.

The mean maximum pullout strength for the awl group was 810.8 ± 40.1 N, while that of the drill group was 765.6 ± 43.4 N, indicating a statistically significant 5.6% higher mean maximum pullout for the awl over the drill. Stiffness and strain were also assessed for both groups, but their differences were not statistically significant.

The reviewed study interestingly questioned a specific aspect of a commonly performed surgery: did the method of preparation for ACDF screw holes make a difference? This is a salient question given the importance of optimizing fixation and stability to reduce hardware complications and improve clinical outcomes as a whole. While the current study may or may not have found differences that would translate to differences in clinical outcomes, it makes one think about this procedural difference.

The authors acknowledge study limitations. In addition to the above-noted question of clinical significance, the testing constructs used a three-dimensional, printed, biomimetic system which had advantages and limitations relative to cadaveric models. There also could have been variations in freehand screw placement, limitations to the testing process, and constraints of the specific implants assessed.

Overall, this reviewed study provides insights into a previously underexplored factor with ACDF screw pullout strength. In doing so, the study showcases the potential that an awl-guided technique may have in placing ACDF screws. The findings of this thought-provoking study bear consideration for clinical practice.