The effect of tip geometry on the mechanical performance of unused and reprocessed orthopaedic drill bits

Surgical Drill Bit Design and Thermomechanical Damage in Bone Drilling: A Review

As drilling generates substantial bone thermomechanical damage due to inappropriate cutting tool selection, researchers have proposed various approaches to mitigate this problem. Among these, improving the drill bit design is one of the most feasible and economical solutions. The theory and applications in drill design have been progressing, and research has been published in various fields. However, pieces of information on drill design are dispersed, and no comprehensive review paper focusing on this topic. Systemizing this information is crucial and, therefore, the impetus of this review. Here, we review not only the state-of-the-art in drill bit designs-advances in surgical drill bit design-but also the influences of each drill bit geometries on bone damage. Also, this work provides future directions for this topic and guidelines for designing an improved surgical drill bit. The information in this paper would be useful as a one-stop document for clinicians, engineers, and researchers who require information related to the tool design in bone drilling surgery.

Reprocessing Standards for Medical Devices and Equipment in Otolaryngology: Safe Practices for Scopes, Speculums, and Single-Use Devices

Stringent regulatory standards for reprocessing medical devices and equipment have proliferated in response to patient safety incidents in which improperly disinfected or contaminated endoscopes lead to large-scale disease transmission or outbreaks. This article details best practices in reprocessing reusable and single-use devices in otolaryngology, with particular attention to flexible fiberoptic endoscopes/nasophyarngoscopes, nasal speculums, and other clinic and operating room instruments. High-risk devices require sterilization, whereas lower risk devices may be reprocessed using various disinfection procedures. Reprocessing practices have implications for adequacy, efficiency, and cost. Nuanced understanding of procedures and their rationale ensures delivery of safe, ethical, and quality patient care.

Postoperative complications associated with external skeletal fixators in cats

OBJECTIVES

The objective of this study was to quantify complications associated with external skeletal fixators (ESFs) in cats and to identify potential risk factors.

METHODS

A retrospective review of medical records and radiographs following ESF placement was performed.

RESULTS

Case records of 140 cats were reviewed; fixator-associated complications (FACs) occurred in 19% of cats. The region of ESF placement was significantly associated with complication development. Complications developed most frequently in the femur (50%), tarsus (35%) and radius/ulna (33%). Superficial pin tract infection (SPTI) and implant failure accounted for 45% and 41% of all FACs, respectively. SPTI occurred more frequently in the femur, humerus and tibia, with implant failure more frequent in the tarsus. No association between breed, age, sex, weight, fracture type (open vs closed), ESF classification, number of pins per bone segment, degree of fracture load sharing, and the incidence or type of FAC was identified. No association between region of placement, breed, age, sex, weight, fracture type (open vs closed), ESF classification, number of pins per bone segment, fracture load sharing and the time to complication development was identified.

CONCLUSIONS AND RELEVANCE

Complication development is not uncommon in cats following ESF placement. The higher complication rate in the femur, tarsus and radius/ulna should be considered when reviewing options for fracture management. However, cats appear to have a lower rate of pin tract infections than dogs.

When Should We Change Drill Bits? A Mechanical Comparison of New, Reprocessed, and Damaged Bits

OBJECTIVES

We assessed how reprocessed and damaged drill bits perform relative-to-new drill bits in terms of drilling force required, heat generated at near and far cortices, and number of usable passes.

METHODS

Nine pairs of nonosteoporotic human cadaveric femora were tested using 3 types of 3.2-mm drill bits (new, reprocessed, and damaged) in 3 investigations (force, temperature, and multiple usable passes). Operating room conditions were simulated. Force and temperature data were collected for each type. The multiple pass investigation measured only force.

RESULTS

New and reprocessed drill bits performed similarly regarding force required and heat generated; both outperformed damaged bits. New and reprocessed bits had a similar number of usable passes in ideal conditions. Damaged bits required nearly 2.6 times as much force to maintain drilling rate.

CONCLUSIONS

Reprocessed drill bits seem to be a viable alternative to new drill bits for fracture treatment surgery in terms of force required, heat generated, and number of usable passes. Drill bits that are damaged intraoperatively should be replaced. In ideal conditions, new and reprocessed drill bits can be used for multiple consecutive cases.

CLINICAL RELEVANCE

Reprocessed drill bits may be as effective as new drill bits, representing potential cost savings for institutions. Both types can be considered for reuse.

Thermal cycling can extend tool life in orthopaedic operating rooms

Thermal cycling is a temperature modulation process developed to improve the performance, durability and longevity of materials. This process has been successfully utilized in the automotive, aeronautic and manufacturing industries. Surgical cutting tools undergo cyclical loading and generally fail by dulling, suggesting that thermal cycling may improve their performance and longevity. Ten 2.5 mm orthopaedic drill bits were randomized, with five undergoing thermal cycling within their sterile packaging and five serving as untreated controls. Using a servohydraulic testing machine, 100 drilling cycles were performed with each drill bit into the diaphyseal region of bovine femurs. After every 25 cycles, data was collected by performing identical drilling cycles into simulated human cortical bone material. Maximum force, maximum normalized torque and drilling work were measured, and a scanning electron microscope was used to measure outer corner wear. After 100 drilling cycles, the maximum drilling force, maximum normalized torque, drilling work and microscopic outer corner wear were all significantly lower for the treated drill bits (p < 0.05). Thermal cycling has the potential to decrease operating room costs and thermal necrosis associated with dull cutting tools. Application of this technology may also be relevant to surgical cutting tools such as saw blades, burrs and reamers.

Multistepped Drill Design for Single-Stage Implant Site Preparation: Experimental Study in Type 2 Bone

PURPOSE

To evaluate an experimental multistepped drill for single-stage implant site preparation by means of real-time analysis of thermal variations during and postdrilling, and by implant stability evaluation.

MATERIALS AND METHODS

Temperature and time were recorded in real time by paired microprobe thermocouples during simulated osteotomy in type 2 bone similes at the cortical and cancellous zones. Three different drilling groups with a new multistepped drill design were compared: Control (2-mm diameter pilot drill + 3.3-mm three-stepped drill + 4.1-mm three-stepped drill); Test A (3.3-mm three-stepped drill); and Test B (4.1-mm three-stepped drill). Implants were inserted, and implant stability was evaluated with the Perio Test Value (PTV). Two-way anova was used to test the independent effects of osteotomy and implant diameter on temperature and stability.

RESULTS

All the drills induced thermal changes without significant differences between groups (p > .05). Drilling in cortical bone produced significant increase of the temperatures in a range of 1.8 ± 0.9°C compared with drilling in cancellous bone (p < .05). ΔT temperatures were significantly higher for test groups in cortical and cancellous bone (p < .05); ΔT10 for all groups showed a reduction of the temperature in a range of 1.7 ± 0.3°C without significant differences between groups (p > .05); the mean time to accomplish drilling was significantly longer in the control group (p < .05); test groups took 10 ± 0.3 seconds less to reach the required drilling depth. PTV values were higher in test groups compared with controls (p < .05).

CONCLUSIONS

The multistepped drills used for single-stage implant site preparation Increase temperature as in comparison with a conventional incremental protocol; Induce the temperature increment in cortical bone compared with the cancellous bone; Reduce drilling time when a multistepped drill is used alone; and Increase implant stability twofold compared with a conventional incremental protocol.

The effect of drill bit, pin, and wire tip design on drilling

Successful penetration of bone is dependent on several factors, including bone quality, drill bit and pin design, and drilling technique. Wires are also used in bone drilling, and the tip configuration can affect the efficiency of bone penetration. Incorrect use of drill bits, pins, and wires may result in complications such as thermal necrosis and hardware breakage.