CORR Insights®: Using Laser Range-finding to Measure Bore Depth in Surgical Drilling of Bone.

In the current study, Demsey and colleagues [3] developed a laser range finder prototype that can be attached to an existing drill to measure the depth holes drilled in bone. The device consists of two laser displacement sensors mounted on the sides of a conventional surgical drill that measure displacement relative to a custom drill guide held against the bone surface in standard fashion. The protype calculated the distance and depth to the bone surface from the difference between the initial position and the breach of the second cortex. The device had acceptable accuracy (within 1 mm to 2 mm) and good precision (within 1 mm). The authors correctly noted that most of the internal fixation systems currently available rely on mechanical depth gauges that are essentially unchanged since the original description in 1948 [5]. Surgeons who have performed osteosynthesis procedures understand well the challenges of reproducing the drill path to insert the depth gauge, the struggles to “hook” the far cortex, especially when soft tissue constraints intervene, and the difficulty visualizing the numbers, which seem to inevitably be on the side facing opposite the surgeon. This all adds up to increased surgical time or improper implant selection, which can lead to wasted implants or complications from screws that are too short or too long. For these reasons, the work of Demsey and colleagues [3] and others [6, 7] seems important. Device manufacturers have developed drills with built-in depth measurement based on drilling force measurements or other proprietary methods [6, 7]. And while these drill systems are already available for clinical use, the user must purchase a new drill system, which may be cost-prohibitive. Demsey and colleagues [3] used laser displacement as an “add-on” measurement tool that could be applied to existing drill systems, allowing for accurate depth measurement without an additional step.