Effect of bone density on the drill-hole diameter made by a cannulated drill bit in cancellous bone

BACKGROUND

When a pilot hole is made prior to a screw's insertion into bone, the same drill bit is used irrespective of the bone quality. However, osteoporotic bone is fragile and this may affect the hole diameter, which is of particular concern in cancellous bone. In this study, the relationship between bone density and drill-hole diameter was investigated assuming a pre-drilling process in screw-only osteosynthesis in the metaphysis and epiphysis.

METHODS

Two types of drill bit (triple-flute [T] and quadruple-flute [Q]) with different shapes and diameters were prepared: type T bits with 3.5 mm and 4.4 mm diameters, and type Q bits with 3.5 mm and 4.2 mm diameters. Drilling was performed manually in simulated bones with four densities: 5, 10, 15, and 20 pounds per cubic foot. We measured the hole diameters with a coordinate measuring machine and analyzed the relationship between the drill-hole diameters and the densities of the simulated bones. We then compared the screw pull-out strength between the two 3.5-diameter drill bits.

RESULTS

In all cases, the diameters of the drill holes were larger than those of the drill bits. The relationship between the drill-hole diameters and the bone densities was a negative linear correlation. Enlarging the hole diameter decreased the screw pull-out strength.

CONCLUSIONS

For cannulated drill bits of 3.5, 4.2 and 4.4 mm diameter, the diameter of the drill hole in cancellous bone obtained by the manual drilling technique tends to be larger in low-density (e.g., osteoporotic) compared to high-density (e.g., healthy) bone.

Design modification of surgical drill bit for final osteotomy site preparation towards improved bone-implant contact

Implant stability significantly impacts accelerated osseointegration, leading to faster patient recovery. Both primary and secondary stability necessitates superior bone-implant contact influenced by the surgical tool required to prepare the final osteotomy site. Besides, excessive shearing and frictional forces generate heat causing local tissue necrosis. Hence, surgical procedure necessitates proper irrigation with water to minimize heat generation. Notably, the water irrigation system removes bone chips and osseous coagulums, which may help accelerate osseointegration and improve bone-implant contact. The inferior bone-implant contact and thermal necrosis at the osteotomy site are primarily responsible for poor osseointegration and eventual failure. Therefore, optimizing tool geometry is key to minimizing shear force, heat generation, and necrosis during final osteotomy site preparation. The present study explores modified drilling tool geometry, especially cutting edge for osteotomy site preparation. The mathematical modeling is used to find out ideal cutting-edge geometry that facilitates drilling under relatively less operational force (0.55-5.24 N) and torque (98.8-154.5 N-mm) with a significant reduction (28.78%-30.87%) in heat generation. Twenty-three conceivable designs were obtained using the mathematical model; however, only three have shown promising results in static structural FEM platforms. These drill bits are designed for the final drilling operation and need to be carried out during the final osteotomy site preparation.

Retrieval of broken bone biopsy needle from the sacroiliac joint - A case report and review of literature

Bone biopsies whether Computed Tomography guided or open, are one of the commonest procedures undertaken. Our literature review proves that bone biopsy needle fracture in a bone is a rare complication with no literature available on a needle fracture in a joint. We report a 7-year-old male who underwent an open needle biopsy. During the procedure, the bone biopsy needle fractured with the distal 2.7 cm fragment being completely embedded in the right sacroiliac joint. Considering the location of the fragment, the standard techniques described in literature for extraction could not be applied due to intra-articular nature of the fragment and the risk of complications. We describe a method using a 2.5 mm drill bit to safely extract the foreign body. We have found that reasonable erosion of adjacent cortex, exposes the needle tip, prevents the needle from shattering and avoids further articular damage. There was an uneventful 15 months follow up. This case highlights the fact that bone biopsy procedure mandates correct technique and supervision and as far as possible a disposable pre-sterilized bone biopsy needle should be used.

Drill Bit Guiding System for Implant Placement

Introduction:

The implant angulation plays a very important role in the outcome of prosthetic and functional outcome. The conventional surgical stents uses a ring system to drill the pilot drill, only the CAD printed stents provides a guide sleeves for the sequential drill for implant placement.

The Purpose of this Study:

The purpose of the study was to fabricate a drill bit guide for the stent to transfer the angulation and implant placement planned using conventional method in prescribed drilling sequence.

Material and Methods:

A surgical stent with a threaded guide ring system was fabricated with internal drill bit guiding system. The interchangeable sequential drilling allows the drill bit to be in predetermined position throughout the procedure.

Results:

The surgical stent with the drill bit guiding system provided less than 1% error with a mean deviation of 0.48%.

Conclusion:

The drill bit guide fabricated has a complete limiting system and transfers the angulation and placement as desired with very minimal or no alteration, which enables the predetermined prosthetic outcome.

In-situ tool wear monitoring and its effects on the performance of porcine cortical bone drilling: a comparative in-vitro investigation

Background

Drilling is one of the most widely used process in orthopaedic surgical operation and the same drill bit is used a number of times in hospitals. Using the same drill bit a several times may be the cause of osteosynthesis and osteonecrosis.

Methods

In the present work, the effect of repeated orthopaedic surgical twist drill bit on the tool wear, force, torque, temperature and chip morphology during porcine cortical bone drilling is studied. Results were compared with rotary ultrasonic drilling (RUD) on the same bone using a hollow drill tool coated with diamond grains. A sequence of 200 experiments (100 with each process, RUD and CD) were performed with constant process parameters.

Results

Wear area on the drill bit is significantly increased as the drill bit is used repeatedly in CD, whereas no attritious wear was found on the diamond coated grains in RUD.

Conclusions

Comparative results showed that cutting force, torque and temperature increased as a function of tool wear in CD as the same drill bit was used a number of times. No significant variation in the cutting force and torque was observed in RUD as the number of drilled holes increased.

Performance test of different 3.5 mm drill bits and consequences for orthopaedic surgery

INTRODUCTION

Drilling of bones in orthopaedic and trauma surgery is a common procedure. There are yet no recommendations about which drill bits/coating should be preferred and when to change a used drill bit.

MATERIALS AND METHODS

In preliminary studies typical "drilling patterns" of surgeons concerning used spindle speed and feeding force were recorded. Different feeding forces were tested and abrasion was analysed using magnification and a scanning electron microscope (SEM). Acquired data were used for programming a friction stir welding machine (FSWM). Four drill bits (a default AISI 440A, a HSS, an AISI 440B and a Zirconium-oxide drill bit) were analysed for abrasive wear after 20/40/60 machine-guided and hand-driven drilled holes. Additionally different drill coatings [diamond-like carbon/grafitic (DLC), titanium nitride/carbide (Ti-N)] were tested.

RESULTS

The mean applied feeding force by surgeons was 45 ± 15.6 Newton (N). HSS bits were still usable after 51 drill holes. Both coated AISI 440A bits showed considerable breakouts of the main cutting edge after 20 hand-driven drilled holes. The coated HSS bit showed very low abrasive wear. The non-coated AISI 440B bit had a similar durability to the HSS bits. The ZrO2 dental drill bit excelled its competitors (no considerable abrasive wear at >100 holes).

CONCLUSIONS

If the default AISI 440A drill bit cannot be checked by 20-30× magnification after surgery, it should be replaced after 20 hand-driven drilled holes. Low price coated HSS bits could be a powerful alternative.

Assessment of experimental thermal, numerical, and mandibular drilling factors in implantology

The main factors that cause an increase in the temperature of the jaw during drilling when implanting teeth are the geometric measurements of the surgical drill, its rotational speed, and its feed rate (cutting speed). Using finite element modelling we analysed the effect of the three variables - the angle of the head of the drill bit, the rotational speed, and the feed rate - on the increase in the temperature of the bone at the point of the drill. This showed that drilling with the angle of the head of the drill bit at 70° generates a lower temperature than when it is at 90° or 118°. The same is true when the drill bit is set at 200 rotations/minute (rpm) compared with 400,800, or 1200rpm. When the feed rate of the drill bit is 120mm/minute it generates less heat than when it is at 90 or 60mm/minute. An increase in temperature during drilling of the jaw has a direct relation with the rotational speed of the drill bit, and a reverse relation to its feed rate. The sharper the drill bit, the lower the temperature during drilling.