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Surgical Retractors Literature Search

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Centers for Disease Control and Prevention, Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008,[edit]

Available at: [1].

  • Details sterility and SAL requirements
  • Steam sterilization (autoclave) overview including temperature ranges and pressurization
  • Flash sterilization alternative requirements

Tim Gessmann affiliated with Department of Surgery, University Hospital Zurich, Markus Schäfer, Atlas of Upper Gastrointestinal and Hepato-Pancreato-Biliary Surgery pp 21-26, 2007[edit]

Available at: [2]

  • General requirements for ideal tissue exposure using surgical retractors
  • Brief comment on self-retaining vs. hand-held retractors


Symmetry Surgical, Symmetry Surgical Retractor Portfolio[edit]

Available at: [3]

  • Extensive catalog detailing commonly utilized surgical retractors and associated names


General Use Retractors - Retractors | Sklar Surgical Instruments, General Use Retractors[edit]

Available at: [4]

  • Extensive catalog detailing commonly utilized surgical retractors


Joanna M. Bassert, John Thomas, McCurnin's Clinical Textbook for Veterinary Technicians, Chapter 30 Surgical Instruments and Aseptic Technique, 8th Edition[edit]

  • Discusses use of most common surgical retractors (includes images)
  • Hand-held vs. self-retaining


Joanna Kotcher Fuller, Surgical Technology: Principles and Practice, 6th Edition, pp 238-239[edit]

  • Detailed images on retractor types
  • Discusses suggest use of each retractor type (advantages and disadvantages)


Colleen J Rutherford, Differentiating Surgical Instruments, 2nd Edition, pp 17-23[edit]

  • Contains alias, anatomical use, description and additional comments on retractor types


M Kanbar, J Wilder, Disposable surgical retractors, US Patent US3729006 A, 1973[edit]

Available at: [5]

  • A hand-held surgical retractor fabricated of resilient plastic material


Charles D. Ray, Surgical retractors, US Patent US4738248 A, 1988[edit]

Available at: [6]

  • Excellent general-use shape retractor


==Rajendra P. Pawar, Sunil U. Tekale, Suresh U. Shisodia, Jalinder T. Totre, and Abraham J. Domb, Biomedical Applications of Poly(Lactic Acid), Recent Patents on Regenerative Medicine 2013 Available at: [7]

  • Discusses the use of PLA in medical device applications
  • Biocompatible
  • Biodegradable
  • Easily Processed
  • FDA approved synthetic degradable polymers


==Timothy M. Rankin, MD, Nicholas A. Giovinco, DPM, Daniel J. Cucher, MD, George Watts, PhD, Bonnie Hurwitz, PhD, d, David G. Armstrong, MD, PhD, DPM, Three-dimensional printing surgical instruments: are we there yet?

  • Briefly describes success of producing a rapid prototype 3D printed surgical retractor using PLA
  • glutaraldehyde sterilization (chemical)
  • PCR tested for bacteria
  • Does not describe intention for re-use, surface quality, or retractor dimensions


Sterilization Requirements[edit]

Reusable devices, including surgical retractors, must be designed to safely withstand sterilization cycles in health care facilities. Additionally, the design must be readily sterilizable to prevent the spread of disease and infection.

Med For information regarding cycle temperatures, durations, and operating conditions, the following resource provides tabulated information. Source: Anderson, Broad, Parente, Validating Reusable Medical Devices: An Overview, Medical Device & Diagnostic Industry, January 1999 https://www.namsa.com/Portals/0/Documents/Validating_Reusable_Devices_1-1996%20.pdf


http://www.cdc.gov/hicpac/Disinfection_Sterilization/13_0Sterilization.html

  • An overview of steam and flash sterilization – the most commonly used sterilization techniques. Optimal for high-temp resistant medical devices.

http://www.cdc.gov/hicpac/Disinfection_Sterilization/13_02sterilization.html

  • Low-temperature sterilization techniques (EtO, Plasma). Optimal for polymers. Very expensive when compared against alternatives.

http://www.cdc.gov/hicpac/Disinfection_Sterilization/13_10otherSterilizationMethods.html

  • Liquid chemical sterilization methods and other increasingly novel methods.

Source: Association for the Advancement of Medical Instrumentation, Comprehensive Guide to Steam Sterilization and Sterility Assurance in Health Care Facilities, 2008 Section 7, Cleaning and Other Decontamination Processes

The first step in the process of re-purposing medical devices is a recommended presoak using an enzymatic solution to loosen the soil. This enables a much easier cleaning step. Rinse thoroughly to remove any remaining residue. Following this step, cleaning must occur. Cleaning removes rather than kills microorganisms. A disinfection of sterilization step will be required following cleaning to ensure it is safe for handling. The accepted standard for the degree of cleanliness is "visible clean". An initial cool water rinse will remove the water-soluble components of blood. Cleaning agents should include high pH detergents, enzymatic solutions, mechanical scrubbing or high pressure water spray to ensure adequate removal of fibrin filaments in coagulated blood. An ideal cleaning agent would include/be: a) nonabrasive b) low foaming c)free-rinsing d) biodegradable e) rapidly dissolve/displace soil f)nontoxic g) efficacious on all types of soil h) long shelf life i) cost-effective

Accomplishing the cleaning step itself can be done multiple ways. Any device must be capable of withstanding manual cleaning. Lukewarm water and detergent solutions (24C-44C) and never in excess of 60C should be utilized. Any cleaning brushes used must be intended for medical device use. Mechanical cleaning is also an option. The process removes soil through an automated cleaning and rinse cycles. Ultrasonic cleaning can be used.

All devices should be rinsed following manual or mechanical cleaning. Water used should not cause staining of the device. To validate the completed cleaning cycle, it is recommended to expose the device to a 2% hydrogen peroxide solution. If the solution bubbles, residual material exists that is acting as a catalyst, indicating that cleaning was inadequate.


Surgical ratchets regularly contact blood and other bodily fluids, and are therefore not considered clean by decontamination. They must be subjected to a microbicidal process. Chemical sterilization may be performed by manually soaking an item in a basin of chemical germicide solution. Options include glutaraldehyde, hydrogen peroxide, hydrogen peroxide - paracetic acid, sodium hypochlorite, and peracetic acid. Gaseous chemical sterilants include EO, hydrogen peroxide gas plasma, chemical vapor combinations, and ozone. Thermal disinfection using hot water is the most common alternative to chemical baths. Sterilization temperatures should operate at temperatures between 121C-135C (steam sterilization).

Source: Association for the Advancement of Medical Instrumentation, Sterilization of medical devices, - Requirements for products labeled "STERILE"

Cleaning procedures must be verified for biological adhesion. In accordance with AAMI ST67, products intended to contact breached skin or compromised tissue, such as a surgical retractor, must have a Surgical Assurance Level (SAL) of 10-6. This number represents the probability of a single viable microorganism occurring on a product after sterilization. To determine this value for each sterilization process, ANSI/AAMI/ISO 11134, ANSI/AAMI/ISO 11135, ANSI/AAMI/ISO 11137, and ANSI/AAMI ST63 should be consulted.


FDA recommendations & requirements include: Source: http://www.fda.gov/downloads/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/UCM253010.pdf 1) Validated method of cleaning a. Physical removal of soil and contaminates to prevent accumulation and transfer

2) Validated method of sterilization a. Microbicidal effect

  • Because retractors are considered a Critical device under the Spaulding Classification, they must be cleaned and disinfected with products having EPA claims for activity against Hepatitis B.
  • Specific requirements and recommendations are available in standards AAMI TIR12 and AAMI TIR30, Designing, testing and labeling reusable medical devices for reprocessing in health care facilities: A guide for medical device manufacturers, and A Compendium of Processes, Materials, Test Methods, and Acceptance Criteria for Cleaning Reusable Medical Devices, respectively.

Handling Stainless Steel Surgical Instruments[edit]

Source: ASTM Standards Section 13, Medical Devices and Services

Guide to provide better understanding of the care of stainless steel surgical instruments intended for reuse. The most utilized stainless steels are martensitic and austenitic. Instruments of these compositions should never be exposed to strong acids or contact salt solutions. Prolonged exposure to chloride-bearing solutions including blood and saline can cause localized corrosion. Abrasive pads should not be used during cleaning, as they may eliminate the necessary passivation layer. Ultrasonic cleaning is highly effective at appropriate temperatures. If utilizing steam sterilization methods, cleaning agents must be completely removed prior to the process to prevent staining of the retractor.

Proposed Testing and Validation Outline[edit]

Based on the above information, the following process is presented for producing 3-D printed surgical retractors.


1) Identify optimal printing parameters and retractor geometries (metal vs. polymer)

2)

    a.Identify appropriate cleaning and sterilization methods
       i.Validate sterility utilizing 3-D printed part (according to FDA standards). SAL must meet 10-6. 
         1.AAMI TIR30
    b.Classify mechanical properties of printed part. It must only be shown that tensile stress of the printed material reliably exceeds the anticipated force required for normal   operating conditions. 

3)Long-term condition testing for both sterilization and cleaning (based on average use time in health care environments)

    a.Mechanical property testing (See 2b)

4)Biocompatibility study (not required for materials regularly used in medical applications)

    a.http://www.iso.org/iso/catalogue_detail.htm?csnumber=44908

5)Accelerated aging study (thermoplastics must demonstrate adequate shelf-life without deterioration of mechanical properties or surface quality)

    a.http://www.mddionline.com/article/general-aging-theory-and-simplified-protocol-accelerated-aging-medical-devices


Plastics Utilized in Medical Applications[edit]

Source: Modjarrad, Ebnesajjad, Handbook of Polymer applications in Medicine and Medical Devices, Dec 10 2013 Medical devices utilize a number of plastics with varying degrees of success. These can include:

  • Polyethylene:Low heat deflection means they cannot be sterilized using an autoclave, EO must be utilized.
  • Polypropylene: Melt temp is high enough to withstand an autoclave sterilization process
  • Polystyrene: Low heat distortion temperature, must be sterilized with EO
  • Polyester: Low hydrolytic stability and low glass transition temperatures, not recommended for use with steam and autoclave sterilization. EO must be used.
  • Polyester (PLA and Other Biosorbable Plastics): Susceptible to hydrolysis and deformation at high temperature, EO cannot be used due to plasticizer reaction with polymer. Gamma sterilization at dry ice temperatures is recommended
  • Polycarbonate: Can be sterilized with the autoclave at temperatures below 125C for an extended lifetime. Can also be used readily with 2% peracetic acid.
  • Polyvinyl Chloride: Steam temperatures exceed the glass transition temperature of unplasticized PVC and therefore cannot be used reliably. EO is recommended
  • Polyethersulfone: Regularly sterilized for long-cycle durations in autoclaves with no significant impact to device integrity
  • Polyacrylate (Acrylic, PMMA): Should not be used with autoclave, EO recommended
  • Polysulfone: PSU can withstand exceptionally long lifecycles at higher temp autoclave sterilization (1000 cycles, 140C)
  • Polyetheretherketone: PEEK can be sterilized by autoclave or EO
  • Thermoplastic Elastomers (TPE, TPU): Compatible with EO sterilization techniques
  • Thermoset Elastomers—Silicone: Moisture and heat resistance make it suitable for autoclave sterilization


Specific polymers approved or in approval for use in 3D printing of medical devices include:

  • MED610, Available at: [8]
  • Nylon680, Available at: [9]


Polycarbonate in Medical Applications[edit]

Medical Applications of Polycarbonate, Douglas G. Powell, Labthink Instruments CO

  • Available at:[10]
  • Polycarbonate has a well-defined niche in the medical device market. Very easily sterilizable using both autoclaves and EO. High-heat grades are recommended for long-life applications that require regular steam sterilization. It is already being used in filter cartridges for renal dialysis, cardiac surgery products such as oxygenators, surgical instruments to replace metal, and IV connection components.


Saga Dental Supply

  • Available at: [11]
  • Widely used in dental applications which require significantly higher reliable autoclave lifetimes.


Polycarbonate for Medical and Laboratory Applications - Makrolon by Bayer MaterialScience

  • Avaiable at: [12]
  • Makrolon is the trade name for polycarbonate
  • No change in dimensions due to water, high creep modulus, high heat deflection temp, isotropic behavior
  • Available in medical grades
  • Biological Compatibility has not been established for multiple use in medical applications
  • Sterilization can be done up to 121C and is suitable for ETO. When higher temperatures are required, Apec can be used up to 134C


Polycarbonate Remains Proven and Preferred for Medical Applications, Cheryl Weckle, Styron Medical Applications

  • Available at: [13]
  • PC has been utilized in medical devices for decades
  • BPA controversy
  • Utilized in hemodialyzers, anesthesia containers, blood oxygenators, arterial filters, IV connectors, endoscopic applications


Polycarbonate has healthy growth potential in health care and medical application segments

  • Available at: [14]
  • High-flow medical grades of PC have been developed with MFR of 20-37 g/10 min.area.


High-performance polymers over metals in health care market

  • Available at: [15]
  • Hohmann retractor was selected for replacement of metal components with Ixef PARA because of strength, surface finish, gamma sterilization compatibility.
  • Reusable device uses AvaSpire PAEK


Sterilization - Tough on germs, tough on plastics too, LaVerne Leonard

  • Available at: [16]
  • Covers the breakdown of sterilization techniques and their impacts on polymer stability. These indicate that PC is widely used in the medical device industry.


Polypropylene in Medical Applications[edit]

ExxonMobil™ polypropylene resins are specifically designed for healthcare and medical applications

  • Available at: [17]
  • ExxonMobil manufactures 3 polypropylene grades for use in medical applications
  • All sterilization techniques are applicable


Polypropylene the material of choice

  • Available at: [18]
  • Light weight, low cost, with high chemical and bacterial resistance
  • PP compounding must be done to use steam sterilization
  • Used in medical vials, diagnostics, petri dishes, IV bottles


Polypropylene takes center stage in medical market

  • Available at: [19]
  • Proteus LSG HS PP, heat stabilized polypropylene, can be repeatedly steam and autoclave sterilized.


PP usage in healthcare sector is poised for a good growth

  • Available at: [20]
  • Not as heat resistant as PC
  • Largest medical application is in hypodermic disposable syringes
  • also used as a nonabsorbable synthetic suture material


A self-made disposable iris retractor in small pupil phacoemulsification

  • Available at: [21]
  • Self-made disposable iris retractor was used safely in clinical trials
  • Disinfected used EO


Cheek Retractor

  • Available at: [22]
  • Already utilized extensively in dental applications


3D Printing in Medical Application Sources[edit]

3D Printing Surgical Implants at the clinic: A Experimental Study on Anterior Cruciate Ligament Reconstruction

  • Available at:

[23]

  • A well-defined, orthogonal, porous PLA screw-like scaffold was printed, then coated with hydroxyapatite (HA) to improve its osteoconductivity
  • Results of this study demonstrate that fabricating surgical implants at the clinic (fab@clinic) with D3DPs can be feasible, effective, and economical


New 3D Printed Medical Tool a Breakthrough for ACL Reconstruction Surgery

  • Available at:

[24]

  • Direct Metal Laser Sintering with Inconel 718 alloy
  • Targeted at ACL reconstruction surgery
  • Discusses importance of 3D printing in medical applications


3D-Printing and the effect on medical costs: a new era?

  • Available at:

[25]

  • Discusses the impact of introducing 3D printing technology to the medical device community
  • Applicable section on cost implications of 3DP medical and dental prostheses


Medical Applications for 3D Printing: Current and Projected Uses

  • Available at:

[26]

  • Customization and Personalization discussion
  • Overview of cost efficiency
  • Discusses potential applications for 3D printing in medicine
  • Covers challenges and associated controversies (including patents and regulations)


Emerging Applications of Bedside 3D Printing in Plastic Surgery

  • Available at: [27]
  • Excellent sources of specific examples of 3D printing models
  • Contains several sources regarding surgical tools, including the article "are we there yet"


Medical rapid prototyping applications and methods

  • Available at: [28]
  • Surgical aid tools: hip resurfacing anthroplasty
  • Overview of design process, but no details


Bleach Sterilization Alternative - Viability[edit]

Chemical Resistance Chart Available at: [29]

  • Sodium Hypochlorite (bleach)in a 15% aqueous solution displays no attack, possibly slight absorption and a negligible impact on mechanical properties with Acrylic, CAB, ECTFE, Fluourousint, HDPE, PEEK, PET, Polycarbonate, Polypropylene, Polysulfate, PVC Type 1, PVC Type 2, PVDF, PTFE, Tecator/Torlon, and UHMW.
  • Sodium Hypochlorite (bleach)in a 15% aqueous solution displays slight attack by absorption, some swelling and a small reduction in mechanical properties when exposed to PPS
  • Sodium Hypochlorite (bleach)in a 15% aqueous solution causes material decomposition or dissolution of Nylon Type 6,6


The Effectiveness of Bleach as a Disinfectant of Injection Drug Equipment Available at: [30]