VELYS: a technical system profile

In brief

• DePuy Synthes VELYS Robotic-Assisted Solution is an image-free/CT-free knee platform.
• Landmarks are collected in theatre and the surgeon creates and revises the plan.
• A table-rail-mounted arm constrains the saw handpiece in each resection plane and tracks leg movement.
• The surgeon activates, holds and advances the saw; the system does not operate independently.

Architecture and applications

VELYS uses optical tracking and intraoperative landmark capture rather than preoperative CT. FDA K202769 describes TKA with ATTUNE, while K240211 separately covers UKA with SIGMA HP Partial Knee in the relevant configuration. This does not imply open compatibility with every implant.

The robotic device mounts on the operating-table rail. It controls saw handpiece position and orientation for each resection plane. The saw remains surgeon-held and surgeon-activated. Functionally this is not a CORI-style handheld robot because the handpiece is mechanically associated with a positioning arm.

Intraoperative planning

After references are fixed, the clinician collects bony landmarks. Software builds a geometric representation and displays component-position and balance parameters. The surgeon interprets these data and revises the plan before cutting. Avoiding CT removes the preoperative digital stage but makes sound intraoperative registration essential.

During resection, the arm maintains the permitted plane. Tracking enables compensation for leg movement within the documented workflow. The clinician still establishes exposure, protects tissue, controls the saw and verifies depth and final cuts.

Typical sequence

1. Establish the indication clinically.
2. Set up the system and optical references.
3. Capture landmarks and verify registration.
4. Plan component position and balance intraoperatively.
5. The surgeon adjusts and approves parameters.
6. The arm sets the plane and the surgeon controls the saw.
7. Cuts are checked and surgery completed.

Evidence

Constraining a plane is not an autonomous cut

VELYS positions the saw handpiece so the blade retains its planned orientation. The surgeon activates and advances the saw through bone while controlling surrounding structures. The arm does not choose the next resection or begin cutting independently. “The robot makes the cut” is therefore imprecise: the platform mechanically constrains a clinician’s action.

Optical tracking relates the device to moving anatomy. Motion compensation depends on valid registration and visible references. It does not replace limb control, direct observation or verification after each step.

What CT-free means

No preoperative CT does not mean no patient-specific plan. Geometry is captured intraoperatively, after which the clinician selects component parameters and evaluates balance. Avoiding a separate scan should be described alongside the time and verification required to collect those data in theatre.

A CT-free workflow cannot automatically be called faster or less accurate. Those questions need direct studies of comparable cases, including setup, registration, repeat checks and learning curve.

Controls and fallback

Before cutting, the team verifies patient, side, stable references and correspondence between digital landmarks and anatomy. The surgeon approves each plane and needs a safe fallback if tracking is lost or the arm fails. Software completion does not replace measurement of the executed resection.

Bench, cadaveric and clinical findings answer different questions. Reduced angular error in a laboratory shows geometric performance under specified conditions, not pain, function, complications or implant longevity.

A paired cadaveric study involving 40 specimens and five surgeons compared VELYS with conventional instruments. Errors and outliers above 3° were lower for several angular parameters, while other parameters were equivalent. This was an in-vitro study partly funded by DePuy Synthes. It does not establish differences in PROMs, complications, revision or implant survival.

For UKA, the FDA summary identifies bench, cadaveric and usability testing; clinical data were not required for clearance. Clearance itself therefore cannot become a claim of clinical superiority.

Limits and questions

The platform depends on accurate registration and continuous tracking. Functions and implant compatibility are configuration- and market-specific. VELYS Knee properties cannot be transferred to VELYS Hip Navigation or Spine. CT-free does not mean there is no digital model or navigation.

Does the saw move itself? No. The surgeon holds, activates and advances it; the arm constrains the plane.

Is CT required? Not for the described knee workflow.

Is faster recovery proven? The cited study measures cadaveric accuracy, not patient recovery.

This material does not select treatment for an individual. Sources reviewed 8 August 2026; scheduled review August 2027. Author: RoboOrthoClub editorial team. Relevant conflicts must be disclosed.