Measurement Support - Lumo Socket and Spacer

Lumo ▸ Lumo Socket and Spacer
Part 1 · Socket

Do you want a Lumo socket?

The socket type determines which measurement reference and which built-in offset the calculator uses.

How do you want to determine your socket size?

Choose photo measurement with a quality check, or manual measurement with a tape.

Lumo socket sizes

Each Lumo socket size is a length letter (A–F) plus a circumference number (1–4). Use your measured stump length and circumference to read off the size.

Measure stump length L4
Stump length L4 (mm)
Measure circumference C0
Circumference C0 (mm)
Stump length L4 (mm)
A45–50 B51–65 C66–85 D86–105 E106–125 F126–145
Circumference C0 (mm) 1110–130 A1B1C1D1E1F1
2131–155 A2B2C2D2E2F2
3156–190 A3B3C3D3E3F3
4191–235 A4B4C4D4E4F4

The socket takes a TPU insert (always in 5 mm steps): 5 mm for size A, 10 mm for size B, 15 mm for the rest.

Provisional sizing — pending final approval.

Next, the app computes the recommended spacer.

Print & Validate Template

Print the macu4 measurement template at 100% scale (no scaling). Make sure you use a credit-card-sized card to control that the template was printed correctly — place it on the card field, it must fit exactly. Note: a business card does NOT have credit-card-sized dimensions. Leave the card on the template for the photos.

Printer White A4 paper White US Letter paper Credit-card-sized card
Print and validate template

Mark Elbow Crease

Using a skin-friendly pen, draw a straight line through the elbow crease. This serves as a reference for the photos.

Skin-friendly pen (dark ink)
Mark elbow crease

Take 3 Photos

Photo 1: Align the affected arm along the dashed line. Elbow touches the logo circle on the template.
Photo 2: Rotate the arm 90° so the medial epicondyle is centered on the logo circle.
Photo 3: Place both arms side by side on the template. Take the photo from at least 75 cm distance.

Smartphone / Camera Helper person
Arm position Both arms comparison

Send photos to macu4 for validation

macu4 will check that the photos meet the measurement requirements before you continue with the spacer calculator.

Select Photos
JPG, PNG, HEIC — max 10MB each

Checking photo quality...

Part 2 · Spacer measurement

L4 — Affected arm

Measure from the Epicondylus Medialis to the distal part of the stump on the affected arm.

L4 measurement on affected arm
mm
Epicondylus Medialis → distal part of the stump

L5 — Non-affected arm

Measure from the Epicondylus Medialis to the middle of the palm on the non-affected arm.

Socket measurement reference
mm
Epicondylus Medialis → middle of the palm (non-affected arm)

Your Lumo Socket and Spacer

Based on your measurements and socket type, the calculator picked the closest available Lumo spacer size.

Recommended spacer
—
mm

Tips

  • Ensure good lighting and no shadows on the template when taking the photos.
  • Hold the camera perpendicular to the template at 75 cm – 1 m distance.
  • Lift the arm slightly so soft tissue does not flatten against the template.
  • Available Lumo spacer sizes: A (20 mm), B (35 mm), C (50 mm), D (65 mm), E (80 mm).