Which knees will fight your robot? The rating is taken before the skin is open.
Functional alignment balances most knees by moving the components inside published boundaries and leaving the ligaments alone. The knees it cannot balance are predictable in clinic: the stiff varus knee with posterior osteophytes tenting the capsule, and the valgus knee whose medial ligament is spent. Under TEAM those are the episodes that carry the manipulation, the revision, and the post-acute spend.
Ten things you already know in clinic.
Deformity items come from the long-leg film and the stress exam; laxity items from varus and valgus stress at 0° and 30°, the drawer, the skyline view, and range of motion. Nothing here needs a device.
Functional alignment should balance this knee.
One question: can the components alone balance this envelope?
The rating sorts every knee into one of four answers. Tiers A through C are handled inside one parametric family. Tier D is the honest limit of articular geometry.
Positioning balances it.
The envelope lands within 2 mm of the patient's own reference after the components move inside the boundaries. Stock medial-stabilised geometry. In the published valgus series, 86% of knees ended here with no releases.
The functional-alignment valgus series →The boundaries run out and the medial side is still loose.
Valgus knee, attenuated medial ligament. Geometry supplies what the ligament no longer does: conformity up, a capped medial-thick step, lateralised sulcus and an offset-dome patella for the laterally tracking patella.
Open the valgus preset →Residual stiffness after the osteophytes are accounted for.
Varus knee, posterior osteophytes, contracture. The osteophyte-caused contracture is subtracted first (2.7° to 4.5° by grade); what remains buys distal resection at about 2° per millimetre, whose mid-flexion cost is fed back into the envelope before conformity is chosen.
Leie 2020, osteophyte removal and extension →The ligament is gone.
Extension opening at the magnitude of a fully released medial ligament, about 7 mm. No articular geometry fills that honestly. A varus-valgus constrained post, outside the family, and the inventory should be on the shelf before the case.
Krackow: complete MCL release opens 6.9° →The components move before the implant changes.
Robotic functional alignment restores the patient's constitutional alignment inside a safe window and adjusts the component positions to the measured soft-tissue envelope. Only what is left after that step should change the implant. The reference envelope is the patient's own constitutional target, read from their own bone morphology, with a population laxity reference where none is available.
| Boundary | Range | What it moves |
|---|---|---|
| Femoral coronal | 3° varus to 6° valgus | Extension gap, medial against lateral |
| Tibial coronal | 2° valgus to 6° varus | Extension gap, opposite sense |
| Femoral rotation | 3° internal to 6° external | Flexion gap, and the trochlear sulcus position |
| Final hip-knee-ankle | 177° to 183° | The limb, with the joint line height preserved |
| Gaps | 1.5 mm to 10 mm | Never tighter, never looser |
Anchored where the literature has a number, flagged where it does not.
The score is not the product. The record of how right it was is.
Every rating saved here would be a prediction. If the knee is opened and the envelope is measured, the residual between the two is what would calibrate the rating for that surgeon. Forty episodes before any refit could be trusted. The ledger would never rank surgeons; it would tell one surgeon how their own eye reads a knee. Today it lives in this browser only.
The record side is SurgeonValue.
If you operate on these joints and want the record side (coding, prior authorization and the episode you’re now scored on), that’s SurgeonValue. Its RTM and registry pieces are still in design. This instrument is research only.
SurgeonValue →The hip is live too.
Its envelope is posture rather than flexion: pelvic tilt from standing to seated. Same structure — measure the envelope, position first, escalate the construct only on the residual. A stiff pelvis leaves a cup window a few degrees wide.
The hip instrument →Put the first row in.
Sending this stores your name, email, practice, role and note, with the rating above, this page’s address and the address of the page that sent you here if your browser shares it, with SolvingHealth, the publisher of this site. Nothing is promised in return: no studio access and no reply.
Do not enter patient details: no names, dates of birth, record numbers or anything else that identifies a patient, in the note or anywhere on this page. Stored for calibration research, not as a clinical record.