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LimbLogic VS Frequently Asked Questions
What are the lastest developments with LimbLogic VS?
Can LimbLogic VS be used with Thermoplastic Sockets?
What comes in a LimbLogic VS box?
What is in the Thermoplastic Drop-in Adapter kit?
To do a thermoplastic LimbLogic VS socket, do I need a tooling kit?
How many applications are available from the Resin Kit that comes with the Thermoplastic tooling kit?
Will there be any Summit classes for the thermoplastic socket fabrication?
What changed from the old unit to the new waterproof version of LimbLogic VS?
The pump is waterproof?
May I return my current (1500-series) LimbLogic VS units and get the new waterproof ones (1600 series)?
I currently have a patient using the 1500 series in water and has experienced no problems. Are the 1500 units not waterproof and could he be damaging the unit?
What is the product warranty?
Is there a trial period?
What is the weight of the unit?
What is the battery life?
Is there anything special with the fabrication of the socket?
Is there anything special with the sealing?
Does this work for AK amputees?
What type of maintenance is required for the system?
What are the system settings?
What type of liners are needed with the system?
What is the difference between the settings of inches of mercury (in-Hg) and millimeters of mercury (mm-Hg)?
What is the difference between suction suspension and vacuum suspension?
How does vacuum suspension work?
What L-codes are reimbursed for the LimbLogic VS system?
What is the torque required to attach the LimbLogic VS pump to the prosthesis?
What is the difference between the System Maximum setting and the Upper Set Point?

Q. What are the lastest developments with LimbLogic VS?
A. LimbLogic VS may now be used in fresh water and is waterproof to a depth of 3 meters (10 feet) for up to 12 hours at a time. Ohio Willow Wood has also released a thermoplastic drop-in adapter which allows LimbLogic VS to be used in thermoplastic sockets as well as laminated sockets.
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Q. Can LimbLogic VS be used with Thermoplastic Sockets?
A. Ohio Willow Wood has also released a thermoplastic drop-in adapter which allows LimbLogic VS to be used in thermoplastic sockets as well as laminated sockets. When ordering 1600-series LimbLogic VS unit customer need to specify if the unit will be used in a laminated or thermoplastic socket in order for the correct adapter to be packaged and shipped.
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Q. What comes in a LimbLogic VS box?
A. Each single-unit box includes a LimbLogic VS pump, hand-held fob and either a lamination kit (just as has been offered) OR a thermoplastic fabrication kit. The patient accessory kit, patient and prosthetist manuals, battery charger, and international power plug set are unchanged and still included in the box.
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Q. What is in the Thermoplastic Drop-in Adapter kit?
A. kit includes: a drop-in adapter, a Poron Filter, four M6 x 55 screws, a ¼ x 20 Cap Screw, a Plastic Anchor, a Latex Form, and two Forming Sleeves (one large, and one small). The kit also includes a fabrication instructional video.
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Q. To do a thermoplastic LimbLogic VS socket, do I need a tooling kit?
A. The thermoplastic drop-in adapter does require a tooling kit. The LimbLogic VS Thermoplastic tooling kit part number is LLV-02100. The tooling kit is reusable and includes: a Resin Kit, a Hole Saw, a Forming Cap, a Tooling Base, a 10mm Cap Screw with a Hex Nut, and a Fender Washer.
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Q. How many applications are available from the Resin Kit that comes with the Thermoplastic tooling kit?
A. The resin kit that is included with the Thermoplastic tooling kit is adequate for approximately 6-8 applications. The resin is available by the gallon from Ohio Willow Wood. Part number is LLV-02102.
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Q. Will there be any Summit classes for the thermoplastic socket fabrication?
A. Our LimbLogic VS courses will incorporate information on the fabrication of thermoplastic sockets. Our technician courses will go more in-depth on this topic. For customer convenience, included in each LimbLogic VS and Thermoplastic Kit (LLV-1600-T or LLV-16020T) is a fabrication video which shows each step of the fabrication process.
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Q. What changed from the old unit to the new waterproof version of LimbLogic VS?
A. In order to make the new 1600 series of LimbLogic VS waterproof Ohio Willow Wood has improved the sealing process and tests each individual unit to guarantee waterproofing. LimbLogic VS has been tested to meet the International Electrotechnical Commission standards rating of IPX8. The standard says that 8 means "The equipment is suitable for continuous immersion in water under conditions which shall be specified by the manufacturer."
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Q. Is the LimbLogic VS controller waterproof?
A. Yes, the LimbLogic VS controller, which is mounted into a prosthesis, is waterproof for FRESH WATER only. The hand-held fob is NOT waterproof and should not get wet. When released on August 3, LimbLogic VS will be the only electronic vacuum suspension system on the market that is safe to use in fresh water, which could include use in inclement weather or a wet environment.
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Q. May I return my current (1500-series) LimbLogic VS units and get the new waterproof version (1600 series)?
A. If the LimbLogic VS units are unopened and are new in the box, Ohio Willow Wood can issue an RMA and credit a customer's account. Ohio Willow Wood will ship a new 1600-series LimbLogic VS and issue a new invoice. The lead time on this is five business days from the date Ohio Willow Wood receives the 1500 series unit(s).
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Q. I currently have a patient using the 1500 series in water and has experienced no problems. Are the 1500 units not waterproof and could he be damaging the unit?
A. LimbLogic VS has been water resistant since the product was launched. If a patient was in a wet environment the LimbLogic VS was usually not at risk. Meeting the testing standards of the International Electrotechnical Commission ensures a LimbLogic VS controller is safe to use in fresh water. The fob is not waterproof and should never get wet.
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Q. What is the product warranty?
A. It is a two year warranty that is competitive with other electronic vacuum systems. Damage from misuse is not covered.
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Q. Is there a trial period?
A. There is a 30 day trial period.
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Q. What is the weight of the unit?
A. The 4-hole controller weighs 190 gm (0.4 lbs).
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Q. What is the battery life?
A. The battery life is dependent upon the quality of the seal and the amputee's activity level. Our testing has shown the system can normally last between 1 day and one week on a patient. It is recommended that the unit be charged daily to keep a constant routine. The fob has a user replaceable CR2 camera battery that should last 6 months with normal usage.
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Q. Is there anything special with the fabrication of the socket?
A. Yes having an airtight socket is critical to proper operation of the overall system. Ohio Willow Wood provides recommended socket fabrication methodology to achieve airtight sockets with Ohio Willow Wood adapters which are included in the kit instructions and available on our website.
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Q. Is there anything special with the sealing?
A. An airtight sealing sleeve in normally required, but there may be other methods to achieve a good vacuum seal.
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Q. Does this work for AK amputees?
A. Yes the system is suitable for BK and AK amputees.
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Q. What type of maintenance is required for the system?
A. The coarse filter (Poron) in the socket must be kept clear of large debris or lint that would block the airflow. The patient's perspiration will form salt crystals in the vacuum lines, so the system should be flushed with water or isopropyl alcohol on a monthly basis as recommended in the user instructions.
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Q. What are the system settings?
A. The vacuum is adjustable from 0 to 20 in-Hg (508 mm-Hg) with most BK patients using a 10 to 16 in-Hg upper set point. The default control range is a span of 6 in-Hg.
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Q. What type of liners are needed with the system?
A. Ohio Willow Wood testing has been done with Alpha MAX and Alpha DESIGN Liners. The MAX fabric provided the best compatibility with the vacuum.
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Q. What is the difference between the settings of inches of mercury (in-Hg) and millimeters of mercury (mm-Hg)?
A. The LimbLogic system displays vacuum settings in inches of mercury. To convert from inches of mercury to millimeters of mercury simply multiple by 25.4.
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Q. What is the difference between suction suspension and vacuum suspension?
A. Both methods use a difference in atmospheric pressure to attach the socket to the residual limb. Suction suspension normally uses a passive expulsion valve to allow air to exit from socket, but only creates a negative pressure differential when the limb begins to move. Vacuum suspension uses an active pump to create a negative pressure differential which doesn't depend upon the limb position.
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Q. How does vacuum suspension work?
A. The vertical extraction holding force is determined by the diameter of the socket at the sealing point on the limb. The limb in the socket behaves much like a syringe plunger when the syringe is blocked. The vertical holding force is equal to the cross sectional surface area of the limb at the sealing point multiplied by the pressure differential. A negative air pressure is created between the outside of the fabric coated liner and the airtight socket when the vacuum pump pulls the air from the between the liner gel and socket wall. The negative air pressure pulls the liner towards the wall of the socket. The liner gel creates a similar airtight seal to the limb, so when the liner is pulled towards the socket, the body's internal interstitial outward force in the limb is pushed towards the socket and holds the limb firmly in place. The side force stabilizes the limb in the socket.
F ≈ Area * Pressure ≈ π * (C/2)2 * P ≈ 0.39 * C * C * P (assumes a round limb shape at sealing point)

Where
F= approximate vertical extraction force (lbs); C= circumference of limb at sealing point (in); P= negative pressure in socket (in-Hg) [Note: 0.4912 psi/in-Hg]
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Q. What L-codes are reimbursed for the LimbLogic VS system?
A. L-5781 = Vacuum pump, L-7368 = Lithium ion battery charger.
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Q. What is the torque required to attach the LimbLogic VS pump to the prosthesis?
A. The M6 flathead screws provided should be tighten to 9 ft-lbs or 12 N-m of torque.
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Q. What is the difference between the System Maximum setting and the Upper Set Point?
A. The Upper Set Point (USP) and the System Maximum (SM) settings are related, but they are not the same. The Upper Set Point is easily amputee adjustable by the up/down fob buttons and USP is the highest vacuum level that the pump will regulate to when in automatic mode. The Upper Set Point can not be greater than the System Maximum setting i.e. 0<=USP<=SM. The System Maximum is prosthetist adjustable and it sets what a prosthetist determines is the maximum vacuum level that should be applied to a limb. The largest System Maximum value is limited by the capabilities of the pump hardware and it is set equal or less than 20 in-Hg i.e. 0<=SM<=20 in-Hg.
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