Biologic Augmented Microdrilling Surgery for Multiple and Large Full-Thickness Cartilage Lesions in the Knee: Early Clinical and Radiological Results

Background: Various biologic treatments are available for articular cartilage lesions in the knee, but no one exists that is applicable to the full range of chondral disease and that is compliant with United States Food and Drug Administration regulations. The aim of this study was to evaluate outcomes following microdrilling surgery augmented with postoperative injections of bone marrow aspirate concentrate (BMAC), platelet rich plasma (PRP) and hyaluronic acid (HA). Methods: Eighteen patients with at least one symptomatic, full-thickness chondral lesion underwent arthroscopic microdrilling surgery. Immediately following surgery, patients received an intra-articular injection of fresh BMAC, PRP, and HA. This injection was repeated once per week for 5 consecutive weeks. At 4 and 12 months postoperatively, patients received 3 additional weekly injections for a total of 12 injections. Outcome Measures: IKDC (International Knee Documentation Committee) scores, KS (Knee Society) scores and plain radiographs. Results: The mean treated area was 6.2 ± 4.5 (range, 0.6 - 14.7) cm2. The mean preoperative IKDC and KS scores (±SE) were 43.0 ± 3.2 and 68.3 ± 3.6 respectively. At 24 months postoperatively, IKDC and KS scores improved to 85.3 ± 4.2 and 94.7 ± 4.4, respectively;both changes from baseline were significant (p p = 0.05). This change was greater in patients with preoperative JS p for the difference between groups = 0.1). Conclusions: Microdrilling of cartilage lesions augmented with BMAC, PRP, and HA may be a viable treatment for a range of chondral disease with good early clinical and radiological results.

PENETRATING CHARACTERISTIC OF CHISEL EDGE IN ULTRASONIC VIBRATION MICRODRILLING

It is well known that miniature drills are of poor rigidity. If unbalanced radial forces have occurred, the chisel edge will deviate from the correct position, causing hole positional error and size error. Although some research papers talk about the beginning of the drilling process, most were limited to the study of drill whirling vibration and the distorted polygon shape at the entrance, and few investigated the radial deflection of a drill point in microdrilling. This note chiefly deals with how the drill radial deflection is effectively reduced by a new ultrasonic vibration drilling technology. Also, the authors for the first time present a precise penetration characteristic of ultrasonic vibration drilling.

Research of Ultrafine Cemented Carbides for PCB Microdrills

The nanocrystalline WC-10Co composite powders were produced with the processing method of spray thermal decomposition-continuous reduction&carburization.The grain growth inhibitors of 0.4wt%Cr_(3)C_(2) and 0.4wt%VC were added into the composite powders to obtain advanced ultrafine hardmetals with minimal porosity,defects and discontinuous.The rod samples were formed by extrusion.They were sintered in cacuum with SIP treatment.The sintered rods were made into PCB microdrill samples after polishing.Mechanical properties(such as density,hardness,transverse rupture strenth(TRS),magnetic saturation induction and magnetic coercivity)of the sintered ultrafine cemented carbides were measured.The microstructures of them were investigated by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The experimental results show that the transverse rupture strength of the samples sintered in vacuum with sinterhip(SIP)treatment is more excellent.The grain size could be controlled in a range of 200-400 nm with the help of grain growth inhibitors.And the superfine grained materials have superior strength(3900 MPa)and high hardness(HRA=93.3).These features are ideal for PCB microdrills.

Cutting edge preparation of microdrills by shear thickening polishing for improved hole quality in electronic PCBs

Printed circuit boards(PCBs)are representative composite materials,and their high-quality drilling machining remains a persistent challenge in the industry.The finishing of the cutting edge of a microdrill is crucial to drill performance in machining fine-quality holes with a prolonged tool life.The miniature size involving submicron scale geometric dimensions,a complex flute shape,and low fracture toughness makes the cutting edge of microdrills susceptible to breakage and has been the primary limiting factor in edge preparation for microdrills.In this study,a newly developed cutting edge preparation method for microdrills was tested experimentally on electronic printed circuit boards.The proposed method,namely,shear thickening polishing,limited the cutting edge burrs and chipping on the cutting edge,and this in turn transformed the cutting edge’s radius from being sharp to smooth.Moreover,the edge–edge radius could be regulated by adjusting the processing time.PCB drilling experiments were conducted to investigate the influence of different cutting edge radii on wear,hole position accuracy,nail head value,and hole wall roughness.The proposed approach showed 20%enhancement in hole position accuracy,33%reduction in the nail head value,and 19%reduction in hole wall roughness compared with the original microdrill.However,a threshold is needed;without it,excessive shear thickening polishing will result in a blunt edge,which may accelerate the wear of the microdrill.Wear was identified as the primary factor that reduced hole quality.The study indicates that in printed circuit board machining,microdrills should effectively eliminate grinding defects and maintain the sharpness of the cutting edge as much as possible to obtain excellent drilling quality.Overall,shear thickening polishing is a promising method for cutting edge preparation of microdrills.Further research and optimization can lead to additional improvements in microdrill performance and contribute to the continued advancement of printed circuit board manufacturing.