Envelope studio · knee instrument

Plan the envelope, not the angle.

Instrument 01, worked end to end. Enter compartment opening across the flexion arc and a pre-op rating: the studio positions the components inside published boundaries first, and only what positioning cannot reach shapes the implant — a geometry tier and a design sheet you can print, instead of a target angle nobody's knee actually has.

Honest limit. The mapping constants are design hypotheses to validate, not cleared device rules. Nothing here is cleared, validated, or clinical advice — and nothing you enter leaves this browser.

Input

Kinematic envelope

Opening under a 147 N varus/valgus stress at the ankle minus the forceless pose, mm, at each flexion angle. The extension measurement, sampled across the arc.

mediallateral

Deformity anatomy

Pre-op surgeon rating

Rate in clinic from the stress exam and lateral X-ray. The rating predicts the envelope and the implant tier before the skin is open; the intra-op measurement then scores the prediction.

tier —

valgus · laxenvelope

Flexion30°

Output

Design sheet

Patellofemoral

Soft-tissue envelope

Who it is for — today, and not yet

Individual surgeon

Run the envelope on a case and print the design sheet. No login, and nothing you enter leaves this browser.

Live now

Fellowship programme

Teaching cases with the honest-limit callouts intact — fellows see the arithmetic, not a black box. The curriculum uses this studio as the knee practical.

Live now

Hospital group

One rating convention shared across a group is the next build. It does not exist yet, and nothing is collected in the meantime.

Not built yet

Access

The studio above is open to anyone: no login, no account, and no data retained — it runs entirely in your browser. Nothing here is for sale, and no case data is being gathered.