Biomechanics 1 Q&A
- There is both intrinsic (built within the plastic) and extrinsic (attached to the plastic) forefoot varus support. What seems to be the highest tolerated intrinsic forefoot varus support that does not block first ray plantarflexion at toe off?
- How does the Denton Modification differ from a valgus wedge with both being on the lateral side of the foot orthotic device?
- What is the difference in feel to a patient from 3.0 polypropylene and 5.0 polypropylene?
- What is the difference in feel to a patient with a minimum arch fill to a 4.5 mm arch fill?
- Is the Denton Modification more important for a forefoot varus foot type fully corrected or a forefoot valgus foot type fully corrected?
- If the patient had chronic lateral ankle sprains, or chronic lateral foot and leg symptoms, would you rather see a forefoot varus foot type or a forefoot valgus foot type that you can expertly balance out with your orthoses?
- Making a rearfoot post with 4 degrees of pronatory motion is pretty standard in the industry. Is the motion ground into the plantar medial or plantar lateral side of the rearfoot post after the post is originally made flat to the ground?
- Every Podiatrist that I know has a standard orthotic device that they individualize for various patients. When would you put a 3-4 mm Kirby Skive into your standard prescription?
- Some patients have very prominent medial slips of the plantar fascia requiring a groove into the plastic for less pressure. When this groove is placed on the mold prior to pressing, why does it make the arch less flexible?
- When you watch a patient walk, the first question to ask is: Are they Stable?
When the answer is “No”, ask where is the instability coming from? What are common instabilities patients present with almost everyday in practice?
Bonus Question: Research Required: What is the Australian DC Wedge?
Answers to the above questions:
- 5-6 degrees of intrinsic forefoot varus support
- Denton modification, also called a 0 degree lateral frame fill, does not produce a valgus angulation.
- 3.0 is a softer more flexible feel
- Minimal Arch Fill is fuller support into the arch
- Forefoot Varus when fully corrected can produce a slide effect from medial to lateral and the Denton can block the sliding.
- A Forefoot Valgus foot type corrected supports incredibly under the lateral column.
- Plantar Lateral Grind
- If I say Kirby Skive, you would naturally assume I was talking about a medial skive (as I am here). This intrinsic varus wedge on the medial heel helps control pronation a little bit more. Just remember that there is a lateral Kirby skive for supination control also.
- The groove placed into the plastic makes the plastic much less flexible increasing overall arch support
- Medial pronatory instability, lateral supinatory instability, digital instability, knee instability, pelvic instability, and posterior instability
- DC Wedge is a custom made varus wedge using both inversion canting and Kirby Skives. It does not capture the lateral side of the foot.
