Planned Before Surgery: Computer-Assisted Deformity Correction at Ortho World

Every deformity correction at Ortho World is measured and planned on a computer before the patient comes to the operating theatre. This article explains what that means, how the planning is done, and how digital tools help us explain the plan to you.

Why planning matters in deformity surgery

A crooked or short bone is a three-dimensional problem. The bone may be bent in one plane, twisted, shortened, and translated all at once. If the surgeon corrects at the wrong level or by the wrong amount, the limb can look straighter but still load the knee or ankle unevenly, which leads to pain and early arthritis.

Modern deformity surgery therefore follows a simple rule: measure first, then plan, then operate.

What we measure

Planning starts with calibrated full-length standing X-rays of both legs, from hip to ankle, and side views where needed. On these images we measure:

• The mechanical axis – the line of weight-bearing from the centre of the hip to the centre of the ankle, and whether it passes through the centre of the knee
• Joint orientation angles – standard angles at the hip, knee and ankle that are compared with normal values
• The CORA (Centre of Rotation of Angulation) – the exact point where the deformity lies, which tells us where the bone should be cut
• Limb length difference – measured, not estimated
• Rotation – assessed clinically and, when needed, with CT scans

How the digital planning works

We use Bone Ninja, a deformity-planning application developed at the Rubin Institute for Advanced Orthopedics in Baltimore, together with standard planning methods taught in deformity-correction courses. On the patient's X-ray we can:

1. Mark the joints and draw the mechanical axes
2. Locate the CORA and simulate the bone cut
3. Simulate the correction on screen, angle by angle, and see where the new axis will fall
4. Plan the frame or implant and the correction schedule
5. In growing children, estimate the expected leg length difference at the end of growth using established prediction methods (such as the multiplier method), and review that estimate at each visit

Showing patients their plan

One of the most useful parts of digital planning is that we can show you the plan on screen: where the deformity is, where the bone will be corrected, and how the leg is expected to align afterwards. Families tell us this makes a long treatment far easier to understand and follow.

Where AI fits – and where it does not

We use digital and AI-based tools to help document and review each case in a structured way, organise measurements, and prepare clear explanations and teaching material. These tools help us work carefully and consistently.

They do not make clinical decisions. Every measurement is checked and every plan is made by the surgeon, based on examination, imaging and discussion with the patient. Patient images are de-identified before any digital analysis.

What planning cannot do

Planning improves precision, but bone and soft tissue still heal individually. Muscles, nerves, joint stiffness, bone quality and how closely the treatment plan is followed all affect the final result. That is why every plan includes regular X-rays and adjustments during treatment.

Frequently asked questions

Do I need special X-rays? Usually yes: full-length standing X-rays of both legs, taken with a calibration marker. We will tell you exactly which views are needed.

Can you plan from X-rays sent on WhatsApp? A first opinion is often possible from clear photos of your X-rays. Final planning needs proper calibrated images.

Does computer planning mean robotic surgery? No. The surgery is performed by the surgeon. The computer is used to measure and plan before surgery.

For doctors: Planning follows the standard mechanical-axis and CORA methodology (Paley principles), with Bone Ninja for simulation and the multiplier method for growth prediction. Colleagues are welcome to share full-length radiographs for case discussion.