Limbform generates the trim line of a transtibial socket from a limb scan.

The trim line is the rim of the socket, the curve that sets the height of the wall around the knee. A prosthetist currently draws it by hand for each patient either on a cast or in CAD software. Limbform produces that curve and a manufacturing file from a few landmarks the prosthetist marks on a 3D scan.

What it does

The prosthetist scans the residual limb with a commercial handheld scanner and marks about seven anatomical landmarks on the scan. A rule engine draws the trim curve from the landmarks, and the software checks that the curve is a closed loop, lies on the surface and does not cross itself. The work goes from a limb scan to a socket manufacturing file, STEP for CAD/CAM or STL for printing, offline on a small computer beside the scanner.

Current state

The pipeline runs end to end on a synthetic test limb, and the image above is its output. There is no machine learning in it: the curve comes from rules with explicit values that a prosthetist can read and change. Those values are placeholders until prosthetists review them on real scans. The prosthetist makes the clinical decisions at each step, and Limbform is not a medical device.

The how it works page describes each step and lists sample output files.

If you fit transtibial sockets and want to review generated curves on your own scans, use the pilot form.

Who builds it

Limbform is built by Arthur Gouazé. Questions can go to arthurgouaze@gmail.com.