Summary:
Researchers in the Department of Head and Neck Surgery at UCLA have developed a novel bone depth gauge and deployable mechanism for orthopaedic screw insertion.
Background:
Orthopaedic screws are typically used in surgeries to treat fractures that may have been caused intentionally, such as for tumor resection or joint replacement, or unintentionally, such as those from traumatic events. Screws, whether used in conjunction with plating or as individual lag screws, play a crucial role in stabilizing fractures. An orthopedic depth gauge measures the length of a drill hole in bone to assist with proper screw size selection. Accurate depth measurement is critical, as underestimating screw length can lead to fixation instability while overestimation may cause complications such as tendinopathies, mucosal irritation, or damage to surrounding blood vessels or nerves. Current industry standard depth-gauges consist of a fixed central rod attached to a measuring body, incased in an external sleeve. The rod is inserted into the drill hole, where a hook at the tip catches onto the distant cortex. Once secured, the user can advance the external sleeve until it contacts the bone, revealing a calibrated ruler on the measuring body that corresponds to the hole depth. However, these devices have significant limitations. The central rod is prone to warping and is irreplaceable, while the hook mechanism often catches prematurely on bone, complicating insertion. Many surgeons have raised concerns about instrument retention within drill holes. These challenges contribute to inaccurate measurements across all levels of surgical expertise. Therefore, there is a critical need for a novel depth gauge design to improve accuracy and assist in the ease of use across various orthopaedic procedures.
Innovation:
UCLA researchers in the Department of Head and Neck Surgery have developed a novel bone depth gauge to increase accuracy of measurements, incorporate replaceable parts, improve bone insertion, enhance cortex engagement, and include a deployable mechanism for seamless screw insertion. This design maintains a familiar structure of current industry-standard depth gauges, consisting of a fixed rod, central body, and external sleeve. However, this novel depth gauge introduces a hidden disc and rod locking mechanism for more accurate and secure depth measurements. The fixed rod is detachable, allowing for interchangeability with different drill sizes, ranging from 0.8mm to 6.0mm, or integration with a drill bit for combined drilling and measurement. A lever-operated hidden disc mechanism eliminates premature catching during insertion while enabling a reliable hold. By flipping the lever, the disc rotates horizontally, expanding the rod diameter to create a secure anchor for measurement. The mechanism can be disengaged quickly for easy removal. In rare cases of device stick, the system also allows for quick disassembly, leaving no obstructive parts behind. This innovation has the potential to significantly enhance accuracy, usability, and surgeon confidence across a range of orthopaedic procedures for improved patient outcome.
Potential Applications:
• Orthopedic Surgical Procedures utilizing screws
• Trauma Surgery
• Head & Neck Surgery
• Spinal Surgery
• Pediatric Orthopaedics
• Minimally Invasive Surgeries
• Veterinary Surgeries
Advantages:
• Increased accuracy of depth gauges
• Improved usability through eliminating catching and simplifying insertion
• Replaceable fixed rod and locking mechanism components
• Accommodating of different drill sizes
• Reduced risk of sticking
• Versatile and durable
• Enhanced surgeon confidence
Development Status:
Disclosed in June 2024. A functional PLA prototype is available upon request.
Reference:
UCLA Case No. 2024-185
Relevant Publications:
1. Jernigan, E. W., 3rd, Honeycutt, P. B., Patterson, J. M. M., Rummings, W. A., Jr, Bynum, D. K., & Draeger, R. W. (2018). Accuracy in Screw Selection in a Cadaveric, Small-Bone Fracture Model. The Journal of hand surgery, 43(12), 1138.e1–1138.e8. https://doi.org/10.1016/j.jhsa.2018.04.011
2. Liu, P., Xiao, J. X., Zhao, C., Li, X., Sun, G., Yang, F., & Wang, X. (2022). Factors Associated With the Accuracy of Depth Gauge Measurements. Frontiers in surgery, 8, 774682. https://doi.org/10.3389/fsurg.2021.774682
3. Demsey, D., Gomez Arrunategui, J. P., Carr, N. J., Guy, P., & Hodgson, A. J. (2019). Using Laser Rangefinding to Measure Bore Depth in Surgical Drilling of Bone. Clinical orthopaedics and related research, 477(11), 2579–2585. https://doi.org/10.1097/CORR.0000000000000922
4. Beaty, N. B., & Le, T. T. (2009). Mandibular thickness measurements in young dentate adults. Archives of otolaryngology--head & neck surgery, 135(9), 920–923. https://doi.org/10.1001/archoto.2009.109
5. Asprino, L., Consani, S., & de Moraes, M. (2006). A comparative biomechanical evaluation of mandibular condyle fracture plating techniques. Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons, 64(3), 452–456. https://doi.org/10.1016/j.joms.2005.11.017
Lead Inventor:
Ashley Kita, UCLA Assistant Professor-in-Residence in the Department of Head and Neck Surgery