This is part 16 of a series that should be read in order.
Key Points:
- EVA B1 or B2 Balancing are introduced
- The softest is improved as you advance from C3 to C4 to C5
- The stability is weakened as you advance from C3 to C4 to C5
- Rxs for C3, C4, and C5
The Shock Absorption Orthosis (continued)
C3: C3 has been the standard device of orthotists, making a stable, non-plastic device with EVA material. This is a big divergence away from traditional podiatric type devices, with C4 being my personal favorite. C3 is a shaped based B platform and then EVA is pressed over the mold. Typically the EVA is the frame and frame fill combined. And, this frame fill is full, meaning its depth is from the arch height to the ground. Only a slight arch bevel is made in the frame so that the frame fill clears the side of the shoe. It generally does not matter how strong the EVA is, as the full frame fill makes the device very strong (patients can even complain that it feels too hard). However, the shock absorption for the patient mainly comes from the lessening of shock going up the leg at heel strike and push off. The properties of a full contact device.
Prescription for C3 Device:
- Balanced cast to Heel Vertical (only in B1)
- Lab discretion balancing B2
- Can also use same principles in any P, S, or ML device)
- EVA frame is medium 45 durometer or 65 durometer rigid based on personal preference and durometer chosen
- Frame fill is full and typically same durometer as frame
- 18 mm Heel Cup Heights
- Standard Width and Arch Height
- Length can be typical plastic length (OL), to the toe sulcus (SL), and full length (FL)
C4: This is C3 except the frame fill starts out half thick (does not go to the floor). This immediately gives these devices less support, but more flexibility. You can reinforce the arch if too flexible with felt or another material. Typically for C3 and C4 use durometers 45 to 65 for stability and durability. Since there are readily available durometers of 15 and 30, you can give a full frame fill in these less dense materials and still achieve a C4 device.
Prescription for C4 Device:
- Balanced cast to Heel Vertical (only in B1)
- Lab discretion balancing B2
- Can also use same principles in any P, S, or ML device)
- EVA frame can be soft, medium and rigid based on personal preference and durometer chosen
- Frame fill is one half thick (not to the floor) and typically same durometer as frame (typical 45 durometer frame and same for fill of 1/2 thickness) For those who prefer full thickness, then 30 durometer is used for the fill
- 18 mm Heel Cup Heights
- Standard Width and Arch Height
- Length can be typical plastic length (OL), to the toe sulcus (SL), and full length (FL)
C5: This is your C4 device with less dense EVA, less frame fill and more overall padding for cushion. This is the standard for many podiatrists for shock absorption/cushion, and even as a diabetic insole. All EVA devices can be made normal orthotic length, extend out to the sulcus, or full length giving the most support. Therefore, as you go to more flexibility and shock absorption with EVA, you can design the device to the sulcus for better support, and/or use 3/4 frame fill, not one half. It is good to experiment with support and cushion. More support will mean higher durometers, more frame fill, and longer devices. More flexibility with shorter devices, less durometer, and less frame fill. I have fun making various versions based on their symptoms.
Prescription for C5 Device:
- Balanced cast to Heel Vertical (only in B1)
- Lab discretion balancing B2
- Can also use same principles in any P, S, or ML device)
- EVA frame usually is soft, (typically a 30 durometer for C5)
- Frame fill is 1/2 thickness and typically same durometer as frame
- 18 mm Heel Cup Heights
- Standard Width and Arch Height
- Length can be typical plastic length (OL), to the toe sulcus (SL), and full length (FL)
- Typically 1/8 inch spenco for top cover or for Diabetics 1/8 inch poron and covered with 1/8 inch soft plastazote
Review of all the Orthotic Types Being Presented
Corrective Orthotic Devices
↓
- Balancing (B): (B1 and B2)
- Pronators (P): BP, P1, P2, P3, P4, P5, and P6
- Supinators (S): BS, S1, S2, S3
- M/L Instability (M): BML, ML1, ML2, ML3, ML4, ML5, and ML6
- Shock Absorption (C): BC, C1/C2, C3/C4/C5, C6, and C7
Sagittal Plane (H): BH, H1, H2, and H3
