Abrasive water jet cutting as a new procedure for cutting cancellous bone?In vitro testing in comparison with the oscillating saw

Application of a novel osteotomy instrumentation as a substitute tool in total hip arthroplasty

BACKGROUND

Mechanical failure, power shortage, and inadvertent contamination of the oscillating saw occasionally occurs in actualizing femoral neck osteotomy during total hip arthroplasty (THA); however, no appropriate alternative solution is currently available. This study aimed to introduce a novel osteotomy instrumentation (fretsaw, jig, cable passer hook) as a substitute tool while the oscillating saw was unavailable during THA.

METHODS

This study included 40 patients (40 hips) who underwent femoral neck osteotomy during primary THA using the new osteotomy instrumentation (n = 20) and the oscillating saw (n = 20). Clinical data and intraoperative findings of all patients were evaluated.

RESULTS

The mean osteotomy time was 22.3 ± 3.1 s (range, 17-30 s) and 29.4 ± 3.7 s (range, 25-39 s) in the oscillating saw group and in the new osteotomy instrumentation group, respectively (P < 0.001). The Harris Hip Score (HHS) improved in both groups; the mean HSS was 82.3 ± 2.5 and 83.3 ± 3.5 in the oscillating saw group and new osteotomy instrumentation group at 6 months after surgery, respectively (P = 0.297).

CONCLUSIONS

The original osteotomy instrumentation can be an ideal substitute tool for femoral neck osteotomy in THA, especially when the oscillating saw is unavailable or malfunctioning.

Bone Healing Evaluation Following Different Osteotomic Techniques in Animal Models: A Suitable Method for Clinical Insights

Osteotomy is a common step in oncological, reconstructive, and trauma surgery. Drilling and elevated temperature during osteotomy produce thermal osteonecrosis. Heat and associated mechanical damage during osteotomy can impair bone healing, with consequent failure of fracture fixation or dental implants. Several ex vivo studies on animal bone were recently focused on heating production during osteotomy with conventional drill and piezoelectric devices, particularly in endosseous dental implant sites. The current literature on bone drilling and osteotomic surface analysis is here reviewed and the dynamics of bone healing after osteotomy with traditional and piezoelectric devices are discussed. Moreover, the methodologies involved in the experimental osteotomy and clinical studies are compared, focusing on ex vivo and in vivo findings.

Identification of effective elastic modulus using modal analysis; application to canine cancellous bone

Mechanical properties of cancellous bone is of increasing interest due to its involvement in aging pathologies and oncology. Characterization of fragile bone tissue is challenging and available methodologies include quasi-static compressive tests of small size specimens, ultrasound and indentation techniques. We hypothesized that modal analysis of flexure beams could be a complementary methodology to obtain Young modulus. The sampling methodology was adapted such that the uniqueness of the linear dynamic response was available to determine the elastic modulus from natural frequencies and mode shapes. In a first step, the methodology was validated using a synthetic bone model as control. Then, water-jet cutting allowed collecting fourteen small beam-like specimens in canine distal femurs. X-ray microtomography confirmed the microarchitecture preservation, the homogeneity and the isotropy at the specimen scale to derive effective properties. The first natural frequency in clamped-free boundary conditions was used to obtain mean values of Young modulus, which ranged from 210 MPa to 280 MPa depending on the specimen collection site. Experimental tests were rapid and reproducible and our preliminary results were in good agreement with literature data. In conclusion, beam modal analysis could be considered for exploring mechanical properties of fragile and scarce biological tissues.

Improvements of material removal in cortical bone via impact cutting method

Bone cutting with high efficiency as well as low levels of forces and damage has a great significance for orthopaedic surgeries. Due to the brittleness and anisotropy of cortical bone, a conventional cutting process can cause irregular crack propagation and fractured bone chip, affecting the tissue removal process and postoperative recovery. In this paper, a high-frequency impact cutting method is investigated, and its effect on fracture propagation, chip formation and cutting forces is studied for orthogonal cutting. Experimental results show that cracks are deflected by cement lines in conventional cutting, forming fractured blocks or split chips. In impact cutting, the cutting-induced fractures expand along a main shear direction, generating small pieces of triangular segmented chips. Cutting forces are significantly reduced with vibration-induced impacts; especially, the main cutting force is nearly 70% lower than that in the conventional cutting. The main reason for this is much higher strain rates in high-frequency impact cutting than in a conventional process, and direct penetration of fractures across the osteonal matrix without deflections along the cement lines. This results in a straighter path along the main shear plane and totally different chip morphology; so, a lower consumption of cutting energy in the main shear direction reduces the macroscopic cutting force. The results of this study have an important theoretical and practical value for revealing the mechanism of impact cutting, improving the efficiency of osteotomy and supporting the innovation in bone surgical instruments.

Comprehensive analysis on orthopedic drilling: A state-of-the-art review

Bone drilling is a well-known internal fixation procedure to drill a hole, fixing the bone fragments to reduce the susceptibility of permanent paralysis. The success of bone drilling is evaluated based on the extent of osteonecrosis in terms of heat generation, tissue damage, quality of hole, and drilling forces. The appropriate control of cutting conditions, drill geometric parameters, and bone-specific parameters offer bone drilling a viable solution through conventional and non-conventional drilling techniques. The majority of the published research work considers only limited parameters and tries to optimize the drilling parameters and performance measures. However, bone drilling involves numerous conventional and non-conventional drilling parameters and technologies. In order to develop a better understanding of all the studied parameters and performance measures, there is a dire need to develop a framework. The key objective of this review study is to establish a hierarchy of the framework by collecting almost all the parameters studied until now and addressed the relationship between parameters and performance measures to diminish the controversies in the published literature. Therefore, this framework is novel in nature, organizing all the parameters, performance measures, logical comparisons, and limitations of studies. This holistic review can help medical surgeons and design engineers to understand the complicated relationship among parameters and performance measures associated with this state-of-art technologies. Also, modeling, simulations, and optimization techniques are included to explore the application of such techniques in recent advancements in orthopedic drilling.

Multi-objective performance investigation of orthopaedic bone drilling using Taguchi membership function

Orthopaedic bone drilling attacks the surrounded bone cells and tissues in terms of thermal and mechanical in such a way that these cells can get damaged permanently. This damage to the surrounding of drill point upsurges the rehabilitation time of injury and in some cases leads to the failure of the bone screw joint. This study is based on the optimization of multiple response characteristics to minimize the damage during the bone drilling. All real-life problems, including bone drilling, require the multiple response optimization for getting a combined optimization result for all countable response characteristics. The Taguchi optimization technique is observed as a highly recommended tool for single response optimization. This article uses the Taguchi technique with little modification of membership function that will help to convert the multiple response characteristics into single response and further optimize it as a single function of performance. Rotational speed, feed rate of tool at three different levels with three different kinds of drilling tools are the drilling parameters selected for the study. The objective of this study is to minimize the surface roughness and thrust force simultaneously. Analysis of variance helps to find the percentage contribution and significance of each parameter on the performance.

Robotic guided waterjet cutting technique for high tibial dome osteotomy: A pilot study

BACKGROUND

Oscillating saws generate high levels of heat (up to 150°C), which can lead to tissue necrosis, delayed healing and infection. Abrasive waterjet-cutting techniques have been described as a new tool to perform bone cuts, with less heat generation.

METHODS

Four lower-limbs of four human alcohol conserved cadavers were tested. Navigation references were attached to the tibia and an intraoperative fluoroscopy-based 3D scan was obtained. A 1.2 mm diameter nozzle was attached to a robotic arm, which was guided to follow a pre-specified path. In addition, a self-designed jet-absorber was applied to protect the posterior neurovascular structures. Magnesium was added as an abrasive substance to improve the cutting ability of the waterjet.

RESULTS

In all four cadavers, the osteotomies could be carried out as planned, resulting in smooth cut surfaces. No damage to the soft-tissues was observed.

CONCLUSIONS

The advantages of abrasive waterjet-cutting give it great potential in orthopaedic surgery. A current disadvantage is the amount of magnesium solute that is left on the surgical field and can be harmful to the patient.

Intraosseous heat generation during sonic, ultrasonic and conventional osteotomy

OBJECTIVES

To assess heat generation in osteotomies during application of sonic and ultrasonic saws compared to conventional bur.

METHODS

Two glass-fiber isolated nickel-chromium thermocouples, connected to a recording device, were inserted into fresh bovine rib bone blocks and kept in 20 ± 0.5 °C water at determined depths of 1.5 mm (cortical layer) and 7 mm (cancellous layer) and 1.0 mm away from the planned osteotomy site. Handpieces, angulated 24-32°, were mounted in a vertical drill stand, and standardized weights were attached to their tops to exert loads of 5, 8, 15 and 20 N. Irrigation volumes of 20, 50 and 80 ml/min were used for each load. Ten repetitions were conducted using new tips each time for each test condition. The Mann-Whitney-U test was used for statistical analysis (p < 0.05).

RESULTS

Both ultrasonic and sonic osteotomies were associated with significantly lower heat generation than conventional osteotomy (p < 0.01). Sonic osteotomy showed non-significantly lower heat generation than ultrasonic osteotomy. Generated heat never exceeded the critical limit of 47 °C in any system. Variation of load had no effect on heat generation in both bone layers for all tested systems. An increased irrigation volume resulted in lower temperatures in both cortical and cancellous bone layers during all tested osteotomies.

CONCLUSION

Although none of the systems under the conditions of the present study resulted in critical heat generation, the application of ultrasonic and sonic osteotomy systems was associated with lower heat generation compared to the conventional saw osteotomy. Copious irrigation seems to play a critical role in preventing heat generation in the osteotomy site.

Comparative study for surface topography of bone drilling using conventional drilling and loose abrasive machining

Drilling through the bone is a complicated process in orthopaedic surgery. It involves human as a part of the work so it needs better perfection and quality which leads to the sustainability. Different studies were carried out on this curious topic and some interesting results were obtained, which help the orthopaedic surgeon on the operation table. Major problems faced during bone drilling were crack initiation, thermal necrosis and burr formation. The surface topography of the bone is an indirect indication for the sustainability of bone joint. In this study, a comparison is made between conventional and a loose abrasive unconventional drilling technique for the surface characterization of the bone. The attempt has been made to show the feasibility of bone drilling with non-conventional technique and its aftereffect on the bone structure. The burr formation during conventional bone drilling was found to be more which leads to problems such as crack initiation and thermal necrosis. Scanning electrode microscope and surface roughness tester were used to characterize the surface of the fine drilled bone specimen and the results testified quite better surface finish and least crack formation while drilling with loose abrasive unconventional technique.

Waterjet drilling in porcine bone: the effect of the nozzle diameter and bone architecture on the hole dimensions

Using waterjets instead of rigid drill bits for bone drilling can be beneficial due to the absence of thermal damage and a consequent sharp cut. Additionally, waterjet technology allows the development of flexible instruments that facilitate maneuvering through complex joint spaces. Controlling the drilling depth is of utmost importance to ensure clinical safety, but is challenging given the local variations in structural properties of the bone. The goal of this study was to deduce a descriptive mathematical equation able to predict the hole depth and diameter based on the local structural properties of the bone at given waterjet diameters. 210 holes were drilled in porcine femora and tali with waterjet diameters (Dnozzle) of 0.3, 0.4, 0.5 and 0.6mm at a pressure of 700bar and a 5s jet time. Hole depths (Lhole), diameters (Dhole) and bone architectural properties were determined using microCT scans. The most important bone architectural property is the bone volume fraction (BV/TV), resulting in the significant predictive equations: Lhole=34.3 (⁎) Dnozzle(2)-17.6 (⁎) BV/TV+10.7 (R(2)=0.90, p<0.001), and hole Dhole=3.1(⁎) Dnozzle-0.45(⁎)BV/TV+0.54 (R(2)=0.58, p=0.02), with Lhole, Dhole and Dnozzle in mm. Drilling to a specific depth in bone tissue with a known BV/TV is possible, thereby contributing to the safe application of waterjet technology in orthopedic surgery.

Healing of osteotomy sites applying either piezosurgery or two conventional saw blades: a pilot study in rabbits

PURPOSE

The purpose of this study was to compare bone healing of experimental osteotomies applying either piezosurgery or two different oscillating saw blades in a rabbit model.

METHODS

The 16 rabbits were randomly assigned into four groups to comply with observation periods of one, two, three and five weeks. In all animals, four osteotomy lines were performed on the left and right nasal bone using a conventional saw blade, a novel saw blade and piezosurgery.

RESULTS

All three osteotomy techniques revealed an advanced gap healing starting after one week. The most pronounced new bone formation took place between two and three weeks, whereby piezoelectric surgery revealed a tendency to faster bone formation and remodelling. Yet, there were no significant differences between the three modalities.

CONCLUSIONS

The use of a novel as well as the piezoelectric bone-cutting instrument revealed advanced bone healing with a favourable surgical performance compared to a traditional saw.

Accuracy in planar cutting of bones: an ISO-based evaluation

BACKGROUND

Computer- and robot-assisted technologies are capable of improving the accuracy of planar cutting in orthopaedic surgery. This study is a first step toward formulating and validating a new evaluation methodology for planar bone cutting, based on the standards from the International Organization for Standardization.

METHODS

Our experimental test bed consisted of a purely geometrical model of the cutting process around a simulated bone. Cuts were performed at three levels of surgical assistance: unassisted, computer-assisted and robot-assisted. We measured three parameters of the standard ISO1101:2004: flatness, parallelism and location of the cut plane.

RESULTS

The location was the most relevant parameter for assessing cutting errors. The three levels of assistance were easily distinguished using the location parameter.

CONCLUSIONS

Our ISO methodology employs the location to obtain all information about translational and rotational cutting errors. Location may be used on any osseous structure to compare the performance of existing assistance technologies.