by Jeff McDaniel, ATP
Intimidation is the word that comes to mind for many RTS’s when creating a molded seating system. After all, there is little room for error, and modifications after the seating system has been created are usually not possible. And then there is the labor, time, effort, and skill. But we have chosen our career path to help our clients, not to choose the path of least resistance. Even though creating a mold may not be easy, it is rewarding and all of the work is well worth the result when the final product is appropriate.
The first step in creating a molded seating system is knowing when it is needed. It is my opinion that custom molds are under utilized in our industry, probably due to the aforementioned obstacles. However, a custom mold can address numerous issues not attainable via manufactured backs and cushions. A custom mold can:
• Evenly distribute pressure for skin protection
• Relieve pressure points via soft spots
• Correct postural deformities more effectively than standard seating
• Increase function via proper positioning
• Prevent sliding out of the seating system by wedging or troughing
• Improve vision field by accommodating kyphosis
• Improve head control by balancing the torso and bringing the head to midline
In order to create an effective seating system, there are a few tools that are necessary but more importantly, it is critical that the mold be created with the input of an occupational or physical therapist. A knowledgeable therapist not only brings an extra set of eyes but the knowledge necessary to create a functional and appropriate system. Also, an involved family member or caregiver greatly increases the probability of a positive outcome.
First of all, it is critical that a mat exam be performed. This is necessary to ascertain range of motion, flexibility, respiratory function, reflexes, and muscle tone. This is probably the most critical part of the formula as it is the precursor of the mold itself. Once this has been completed, it is time to create the mold. But first, let’s go through the necessary tools.
• Simulator – A frame with a seat and back bag filled with polystyrene beads. This will allow you to create a “simulation” of the mold by pulling a vacuum on the bags resulting in a firm but malleable surface.
• Digitizer – Captures a digital image of the finished simulation and is then emailed to the manufacturer to create the molded seat and back.
• Pressure Mapping System – A digital pad placed under the patient’s bottom and back to isolate pressure areas, which can then be addressed while capturing the mold.
• Pulse Oximeter – Used to monitor respiratory function while creating the mold
• Tape measurer – Used to take measurements of the overall size of the mold in order to configure the size of the wheelchair to accommodate the system.
• Camera – Used for funding and verification of the before and after.
Once you have completed the mat exam, you now know your goals. Are you correcting or accommodating? Are there any pressure concerns such as a history of pressure ulcers? Are there any reflexes present such as hip extension tone? All of these issues will need to be addressed. Common knowledge states to start with the seat cushion but I frequently will start at the seat, complete the back, then finalize the seat. I find that I get a better outcome as molding the back frequently makes changes in the position of the client’s pelvis. If you are correcting an obliquity, it is important to “build up” one side of the seat simulator bag to level the pelvis. Just keep in mind that the more correction there is at the pelvis usually translates into more pressure and/or correction of the back. If accommodating the pelvis, try and build up or trough out the seat simulator enough to bring the client’s head to a midline position. When molding the back, I first fill in the posterior portion of the bag by standing behind the simulator and pushing the beads into the client’s back. This “fills in” the gaps. I then pull the laterals into a supportive position. Just remember not to over do it. A mold does not typically breath very well and can be very hot. Since perspiration is not desired, I frequently will create a “3 point” system by applying pressure at the apex of the convexity and above and below the concavity of the scoliosis. Just remember that less is more. Try to make the system as non-restrictive as possible. If this is not avoidable, holes can be drilled into the final mold to allow air circulation.
Now before the patient is taken out of the system let’s do some checks.
1. Is the client’s head midline?
2. Does the system restrict or facilitate functional movements?
3. Does the system protect and/or reduce pressure in concerned areas?
4. Has respiratory function been compromised?
5. Has range of motion been limited or is range of motion at maximum limits?
6. Has field of vision been improved or limited?
These are some general checks I use but there may be other concerns, just make sure that the end result matches your goal for the system.
At this point I measure the width from left to right lateral on the seat and the back as the system can be altered when transferring the client out of the system. It is also important indicate or mark the desired height of the back, the seat depth and the seat to back angle. Once the client has been transferred out, you can either cast or digitize the simulator, depending on what brand of system being used.
Now all of this process is all for nothing if funding hasn’t been procured. Medicare, Medicaid, and most private insurances will readily fund this type of system. The criteria is fairly simple. Medicare and Medicaid criteria state that a custom seating system is medically necessary when a manufactured seat or back will not correct or accommodate the client’s positioning needs. Additionally, I think it is important to indicate the patient’s current positioning, postural deformities, and skin integrity. These criteria, along with a PT/OT seating assessment will typically provide the justification necessary for funding. Photographs are also a great idea as “a picture is worth a thousand words”, so be sure and take before and after pictures. Some, but not all funding sources also allow billing for time and labor, not just the seating system itself. Having said this, it is important to include all options and accessories for your mold before obtaining authorization. I frequently will add summer/winter hardware to the back laterals to provide an appropriate fit when the client is wearing a coat or jacket. Additional covers, hardware, ventilation holes, and additional t-nuts are all covered items.
Finally, it is important to know and understand the various systems and manufacturers. For example, Ride Designs manufactures a system that is lightweight and narrow for manual wheelchair users. PRM is typically easier to modify after the system has been manufactured. And Contour U and OBSS offer different mounting options that are easier to maintain.
In the end, the goal is to provide a successful outcome that takes into consideration the goals that you, the therapist, and the family have created. Just take your time and remember that practice makes perfect. Happy molding!!!