The Importance of Maintaining Close Trim Gaps During Ankle-Foot Orthosis Fabrication

Over the years, we’ve noticed that the trim gaps between the footplate and calf section of some custom-fabricated articulating ankle-foot orthosis (AFO) samples are excessively large, sometimes measuring up to 1/4” between the two sections. The purpose of this post is to highlight the importance of keeping your trim gap as close as possible to ensure proper brace function and joint performance.

Custom Tamarack Orthosis w post relief Poor Flexure Joint Control

We’ve occasionally heard Orthotists report that flexure joints lack sufficient medial-lateral (M-L) stability for some patient diagnoses. However, when the custom fabricated articulating AFO is properly fabricated with narrow trim gaps (no wider than the thickness of a thin-toothed saw blade), flexure joints afford superior rigidity, M-L stability, and performance.

As shown in the image at left, this dorsiflexion assist Tamarack Flexure Joint installation depicts the proper trim lines for both the footplate and calf sections. The footplate and calf section are nearly touching one another; ensuring maximum flexure joint control and better performance.

Shown in the image at right, the trim gap is much too large, resulting in a lack of flexure joint control and potentially reduced device performance. Loss of M-L stability results when the cavity does not sufficiently contain the flexure joint body.

When properly fabricated, flexure joints offer numerous advantages over metal upper and lower extremity joint options, including reduced cost, ease of fabrication, reduced bulk/weight, and extended device performance.

Tamarack Habilitation Technologies developed a comprehensive, step-by-step fabrication guide to help Orthotists, Orthotic Technicians, and Students learn about and optimize their AFO fabrication process when using Tamarack Flexure Joints. This technical resource can be downloaded HERE. Or, if you prefer a hard copy for your orthotic lab, please contact info@tamarackhti.com to request one or more copies. The Tamarack Flexure Joint Product Guide is available in English, French, German, Spanish, and Japanese.

If you have any doubt about whether or not your AFO trim lines are optimized, we encourage you to download or request a copy of the Tamarack Flexure Joint Product Guide. Technical assistance is also available via phone by contacting Tamarack Habilitation Technologies: +1-763-795-0057 o r +1-866-795=0057 toll-free.

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