Written and maintained by CASRAI Editorial Board
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This page describes products and general use; it is not medical advice.
A stack splint is a small, rigid cap that fits over the fingertip and holds the end (distal) finger joint straight. Clinic staff, buyers and students use this page to see how the product is built, which variants exist, and why a size number from one maker’s chart cannot be assumed to match another’s.
What a stack splint is
A stack splint, also called a Stack-type finger splint, is a prefabricated fingertip splint that fixes the distal finger joint in extension. One manufacturer’s catalog lists its indications as avulsion of the extensor tendon, fingertip injuries and nail bed injuries. For how it compares with frog, aluminum, gutter and buddy splints, see finger splint types; for the wider splint family, see what a splint is.
How a stack splint is built
According to the LINK Finger Splints catalog (2022), the splint is a cap over the end of the finger, usually fixed with a hook-and-loop (VELCRO) strap over the middle phalanx. The proximal interphalangeal (PIP) joint is left exposed and remains mobile, and the perforated surface lets air reach the skin. The same catalog lists the cap in skintone (padded and unpadded), clear thermoplastic and black versions.
Types and variants
The variants below are those described in the LINK catalog. Other makers offer their own designs.
| Variant | Indication stated by the maker | Key difference |
|---|---|---|
| Stack type (standard) | Avulsion of the extensor tendon; fingertip and nail bed injuries | Holds the distal joint in extension; PIP joint stays free; perforated surface |
| Stack type, boutonnière | Buttonhole (boutonnière) deformity | 51 mm long; the slight dorsal curvature is left out so the PIP joint is held in extension |
| Stack type, modified according to Drzezga | Avulsion of the extensor tendon; fingertip and nail bed injuries | A continuous slit along the dorsal proximal section lets the splint fit the finger when the strap is fastened and be adjusted as swelling subsides |
| STACTIP (Stactile) | Avulsion of the extensor tendon; fingertip and nail bed injuries | A window over the volar fingertip pad preserves the sense of touch; a large dorsal opening gives air circulation |
Source for every row: LINK Finger Splints catalog (2022), checked 2026-10-30.
Sizes that matter
Stack splints are sized by finger circumference. The table shows one manufacturer’s published chart for the standard stack type in two finishes. The same size number maps to a different circumference in the padded series, so a size number is only meaningful with the maker’s chart for that exact product.
| Size number | Clear thermoplastic (circumference) | Skintone padded (circumference) |
|---|---|---|
| 00 | 3.5 cm | not listed |
| 0 | 4.0 cm | not listed |
| 1 | 4.5 cm | 4.0 cm |
| 2 | 5.0 cm | 4.5 cm |
| 3 | 5.5 cm | 5.0 cm |
| 4 | 6.0 cm | 5.5 cm |
| 5 | 6.5 cm | 6.0 cm |
| 5.5 | 7.0 cm | 6.5 cm |
| 6 | 7.5 cm | 7.0 cm |
| 7 | 8.0 cm | 7.5 cm |
Source: LINK Finger Splints catalog (2022), checked 2026-10-30. The boutonnière version uses a separate, shorter chart (sizes 1 to 7, 4.5 to 8.0 cm in the skintone and clear versions), so it cannot be sized from the table above.
How to choose
The maker pairs each variant with a stated indication (see the variants table) and sizes each product by circumference against its own chart. Check the chart for the exact series and finish, because the padded and thermoplastic series differ by one size step. Use is decided by the treating clinician and the maker’s instructions for use.
Handling and labels
Read the maker’s instructions for use and the size chart printed for the exact product before ordering or stocking it. Assortment packs list their sizes and piece counts: the LINK clear thermoplastic standard assortment is 6 sizes of 5 pieces each, the large assortment is 8 sizes of 5 pieces, and the complete assortment is 10 sizes of 4 pieces. The large and complete assortments include 40 hook-and-loop straps in small and large. For the wider splint family and sizing of related supports, see sling sizes and plaster bandage.
Common mistakes
- Sizing from a different brand’s chart, or from a different series of the same brand. The two series above differ by one size step.
- Treating the standard cap and the boutonnière version as interchangeable. The maker lists them as separate products with separate size charts.
FAQ
What is a stack splint used for?
One manufacturer lists avulsion of the extensor tendon, fingertip injuries and nail bed injuries as indications for its standard stack type, and buttonhole deformity for its boutonnière version (LINK catalog, 2022).
How do you size a stack splint?
By finger circumference against the maker’s own chart for that product series. LINK’s thermoplastic size 1 is listed at 4.5 cm and its padded size 1 at 4.0 cm, so the number alone does not identify a size.
Does a stack splint cover the middle finger joint?
No. The maker states that the PIP joint is exposed and remains mobile in the standard design.
Splints and related first-aid products are listed in the emergency and trauma supplies category at lac.us.
Sources
- LINK Finger Splints catalog, DE/EN edition 2022-11: link-ortho.com catalog PDF, checked 2026-10-30.
