Robotic vs Software-Only TKA Planning

Key takeaways

Robotic total knee arthroplasty (TKA) is now used in a large share of cases, and it does improve certain intra-operative accuracy metrics. But the debate among senior arthroplasty surgeons has shifted from does the robot cut accurately to is the robot worth its cost. The capital price of a robot, plus per-case consumables, is hard to justify when experienced hands already achieve excellent stability, and randomized evidence for better patient-reported outcomes remains limited. What almost no one disputes is the value of the pre-operative planning layer: the ability to do the "surgery before the surgery" virtually, anticipate problems, and standardize the plan. That planning value is separable from the robot. A software-only, vendor-neutral, computed-tomography-based planner can deliver it without the capital cost, which is exactly where a tool like Salnus is positioned, currently Research Use Only (RUO), not a cleared device.

The debate is about the robot, not the plan

Ask a room of arthroplasty surgeons whether a robot is mandatory for a knee replacement and many will say no. In experienced hands, primary TKA already succeeds at a high rate. Robotic systems help move certain metrics, for example reducing outliers in component position, but the incremental gain on hard outcomes is modest and the cost is large: a capital system plus recurring per-case consumables.

The most rigorous syntheses are cautious. A 2021 systematic review by Kazarian, Barrack and colleagues concluded that component malalignment is not a significant driver of the well-documented 15 to 20 percent dissatisfaction rate after TKA, although rotation does relate to implant survival. In other words, precision alone has not translated into a clear satisfaction advantage. This is the crux of the cost-effectiveness argument against robotics.

What surgeons actually defend: planning and data

When the same surgeons discuss where the value really sits, they point not at the robot arm but at two things: the pre-operative plan and the data. The plan lets a surgeon rehearse the case, foresee gap and tracking problems, and enter the operating room with a defined target. The data captured across cases is a tool for continuous learning and refinement.

Both of these are software functions. Neither requires a capital robot. That is the strategic opening: decouple the planning layer that surgeons value from the expensive, cost-contested hardware.

Where a software-only planner fits

A software-only, computed-tomography-based planner can compute the same pre-operative decisions a robotic plan does, without the robot:

The point is not to replace the robot. It is to be the vendor-neutral pre-operative brain that feeds any robot, patient-specific guide, or manual workflow, and to serve the majority of TKAs still done without a robot. For a fuller market view, see our comparison of orthopedic 3D planning software and our note on how planning tools complement robotic systems.

The honest caveat

This is a decision-support and reproducibility argument, not a claim that planning by itself improves outcomes. The evidence that better planning changes hard endpoints is still developing, and benefit appears strongest at the margins, for example less-experienced surgeons or complex phenotypes, rather than universally. The right framing is: standardized, reproducible, patient-specific planning that a surgeon owns, at a fraction of the cost of a robot, and without locking the choice of implant.

Bottom line

The robotics cost debate is not a headwind for pre-operative planning software. It is a tailwind. The layer surgeons defend is the plan and the data, and that layer does not need a million-dollar robot. A vendor-neutral, implant-agnostic, CT-based planner delivers it directly. Salnus builds toward exactly this, as Research Use Only software today, with the surgeon in control of the plan.