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TPLO planning workflow

A typical TPLO planning session in Librevet Ortho. The app handles the technical work of accurate measurement and templating; clinical decisions remain yours.

Before you start

Have your pre-operative radiographs ready, with a calibration marker visible in each.
Decide on your target TPA based on your standard practice. This determines the rotation you’ll need to plan.

Workflow

1. Open the case and calibrate

Calibrate the radiograph you’ll be planning on. See Calibrating radiographs. Every measurement that follows depends on this.

2. Measure the tibial plateau angle

Switch to Measurement and use TPA mode. Place the two construction lines:

The mechanical axis of the tibia, from the inter-condylar eminence to the centre of the talus.
The tibial plateau line along the joint surface.

The TPA reading appears in degrees. Use the loupe (top-bar view settings) for precise endpoint placement on bony landmarks.

3. Plan the osteotomy

Switch to Osteotomy and choose TPLO. Place the crescentic saw arc on the proximal tibia at your chosen pivot.

If auto-trace is available, it can suggest a tibial cortical boundary. Treat it as a starting point — verify the boundary follows the actual cortex before relying on the suggested pivot.

4. Choose the blade radius

The slider offers 8, 10, 12, 15, 18, 20, 21, 24, 27, 30 and 33 mm — the catalogue radii, with the small and large ends included for cats and giant breeds. Choose based on tibial diameter at your planned cut location and your standard practice. The saw arc updates as you change the radius.

5. Plan the rotation

The Current TPA box under Plateau Leveling decides how the cut is made, and the button below it tells you which you are about to get:

Cut and Rotate — the box has an angle in it, either taken from the TPA you measured in step 2 or typed in yourself. The app makes the cut, works out the fragment for you, and turns it from that angle to your target.
Trace and Rotate — the box is empty. You draw the fragment’s outline round the bone yourself, starting at one end of the cut; it closes when you come back to the other end. Then turn it with the rotation handle.

So measuring the TPA first gives you the automatic version, and clearing that box gives you the hand-traced one. Either way the rotation handle stays available afterwards, and the remaining TPA updates live as you turn the fragment.

If you haven’t measured the TPA on the film, the app has nothing to read the plateau’s slope from, so it assumes the film is laid out the way a TPLO is normally planned — cranial to the left, distal end down — and turns the fragment accordingly. Check the plateau afterwards.

6. Place the implant

From the Implants tab, search for the plate you intend to use. Click to arm, then click to commit on the post-rotation position you plan to fix. See Placing implant templates.

Sister-variant swap lets you compare hole counts and sizes without re-aiming the implant.

The case auto-saves. To share with a colleague or referring vet, see Sharing and referrals.

Things to verify before surgery

Calibration is correct (do the cortices look the right thickness?).
TPA reading aligns with your visual sense of the joint.
Auto-trace boundary matches the actual cortex.
Blade radius is appropriate for tibial diameter at your cut location.
Implant size and screw positions are anatomically reasonable.

The app’s automation is intended to reduce time spent on measurement, not substitute for surgical judgement. Verify every step.

Auto-features and their limits

Auto-calibration — finds the marker. Verify the picked marker is correct, especially with stacked or chained markers.
Auto-side detection — reads the L/R marker. Confidence varies with marker quality.
Auto-trace — suggests a cortical boundary. Always adjust to fit the actual cortex.
TPA auto-measurement (where enabled) — places landmarks automatically. Verify both line endpoints.

All four can be wrong. Numerical outputs are only as good as the inputs.