Robotic-assisted systems, such as the ROSA technology, are designed to assist surgeons by providing data-driven insights into a patient’s unique anatomy. The system utilises three-dimensional mapping to help plan implant positioning, aiming to achieve precise alignment and soft tissue balance. While traditional methods rely on mechanical guides and surgical experience, robotic assistance provides a digital interface to verify bone cuts and ligament tension during the procedure.
Unlike conventional techniques that rely on mechanical guides and intraoperative estimation, robotic knee replacement in Singapore provides continuous feedback during surgery. The system tracks bone position throughout the procedure. It automatically adjusts the surgical plan if your leg moves even slightly. This dynamic response ensures the final implant position matches the preoperative plan, regardless of minor shifts that occur during bone preparation.
How ROSA Technology Maps Your Knee
The robotic system begins by collecting anatomical data through two methods: preoperative X-ray imaging (specialised imaging taken before surgery) or intraoperative bone registration (mapping performed during surgery). X-ray-based planning involves imaging your knee before surgery. This generates anatomical data that surgeons use to plan implant positioning and alignment. X-ray-free protocols register bone landmarks during surgery using a probe that touches specific points on your femur (thighbone) and tibia (shinbone).
Both approaches create what surgeons call a “virtual knee”—a digital representation showing bone geometry, existing deformity, and the mechanical axis of your leg (the line running from your hip through your knee to your ankle). The software calculates where implants should sit to restore neutral alignment whilst preserving your natural joint line height. Surgeons can adjust these parameters, testing different implant sizes and positions before any bone is removed.
Registration and Tracking Arrays
Small reflective markers attach to your femur and tibia through pins placed early in the procedure. Infrared cameras positioned above the operating table track these arrays with sub-millimetre precision, creating a live coordinate system. Every surgical instrument also carries tracking markers. This allows the system to display the tool position relative to your bone anatomy on a monitor that the surgeon views throughout the operation.
This continuous tracking serves two functions: it verifies that planned bone cuts match actual execution, and it detects any bone movement that would invalidate the surgical plan. If your leg shifts during the procedure, the system recognises the change and recalculates cutting parameters instantly.
The Bone Preparation Process
Traditional knee replacement uses mechanical jigs—metal guides attached to rods inserted into your bone canals—to direct saw blades during bone cuts. These guides assume average anatomy and require manual adjustment based on visual assessment. ROSA technology replaces this approach with robotically-guided cutting blocks positioned according to your personalised surgical plan.
The surgeon places cutting guides on bone surfaces whilst watching a screen showing real-time deviation from the planned position. The display indicates millimetre and degree corrections needed in all planes: varus-valgus (side tilt), flexion-extension (forward-backwards tilt), and rotation. Only when the guide sits within an acceptable tolerance does the surgeon proceed with bone removal.
Gap Balancing and Soft Tissue Assessment
Knee replacement success depends on balanced ligaments—the implant should create equal tension on inner and outer knee structures through the full range of motion. ROSA quantifies this balance by measuring gaps between bone surfaces in flexion (when the knee is bent) and extension (when the knee is straight). It displays numerical values rather than relying on subjective “feel.”
The system shows whether your medial (inner) and lateral (outer) gaps match, and whether flexion and extension gaps are symmetric. If an imbalance exists, surgeons can adjust bone cuts by fractions of a millimetre or perform targeted ligament releases (carefully loosening tight ligaments). They immediately see how each intervention affects overall balance. This feedback loop continues until measurements fall within appropriate parameters.
Surgical Workflow Differences
A robotic knee replacement procedure follows the same general sequence as conventional surgery—skin incision, joint exposure, bone cuts, trial components, final implantation—but each step incorporates technological verification.
- Joint Exposure: Standard medial parapatellar approach, identical to conventional technique. The kneecap is moved aside to access the joint surfaces.
- Array Placement: Pins with tracking markers are inserted into the femur and tibia, away from the areas where bone will be cut.
- Registration: The surgeon touches specific landmarks on bone surfaces with a tracked probe, teaching the system your anatomy.
- Planning Verification: Preoperative implant positioning is confirmed or adjusted based on registration data. The surgeon reviews alignment, rotation, and sizing before cutting.
- Guided Bone Preparation: Each cutting block is positioned under robotic guidance. The surgeon uses a standard oscillating saw; the robot does not perform cutting autonomously.
- Gap Assessment: Trial components are inserted, and the knee is moved through its range of motion whilst the system measures ligament tension.
- Final Implantation: Permanent components are cemented in place using the verified positions.
💡 Did You Know?
The ROSA system’s tracking cameras can detect positional changes as small as a fraction of a millimetre. This precision exceeds what the human eye can perceive, allowing corrections that would be impossible with manual techniques alone.
Implant Positioning Accuracy
Mechanical alignment in knee replacement refers to restoring your leg to a straight line from hip to ankle. Deviation from neutral alignment correlates with accelerated implant wear and potential instability. Robotic assistance reduces this variability. The system physically cannot position cutting guides outside programmed tolerance; the software prevents progression until alignment requirements are met.
Component Rotation
Rotational positioning of the femoral component (the part attached to your thighbone) affects patella tracking—how your kneecap glides over the implant during bending. Malrotation can cause anterior knee pain (pain at the front of the knee), a complaint after knee replacement. Traditional techniques estimate rotation using anatomical landmarks that vary between patients and can be difficult to identify during surgery.
ROSA technology defines rotational targets based on your preoperative imaging or registered landmarks. It then guides component placement to match these parameters. The surgeon sees rotational deviation in real-time, making adjustments before committing to bone preparation.
Recovery Considerations
The surgical incision, anaesthesia protocol, and rehabilitation timeline for robotic knee replacement mirror those of conventional surgery. Most patients begin walking with assistance on the day of surgery and progress to independent mobility within several days.
Some evidence suggests that precise soft-tissue balancing achieved with robotic assistance may translate into improved early function and reduced pain during rehabilitation. The theory holds that a well-balanced knee may require less protective muscle guarding, potentially allowing faster progression through physiotherapy exercises.
Incision Size and Tissue Handling
ROSA technology does not inherently require a smaller incision than conventional surgery. The surgical exposure must accommodate cutting instruments, trial components, and visual assessment regardless of the guidance method. Surgeons using robotic assistance may achieve adequate visualisation through modestly smaller incisions due to enhanced planning precision. However, this varies by surgical technique and patient anatomy.
⚠️ Important Note
Robotic assistance enhances surgical precision but does not replace the skill and judgement of your orthopaedic surgeon. The technology serves as a guidance tool. All decisions regarding bone cuts, ligament releases, and implant selection remain under the surgeon’s control.
Clinical Considerations for Robotic-Assisted Surgery
Robotic assistance is one of several modalities available for total knee replacement. Clinical considerations for this approach include:
- Personalised Mapping: The ability to create a digital model of the joint to assist in pre-surgical planning.
- Intraoperative Data: Provides real-time measurements of ligament tension (gap balancing), which the surgeon uses to guide adjustments.
- Consistency: Aims to provide a reproducible method for executing bone cuts according to the planned alignment.
The long-term clinical outcomes of robotic-assisted knee replacement compared with conventional techniques are the subject of ongoing clinical studies. The choice of technique should be discussed with your surgeon based on your specific joint anatomy and medical history.
What Our Orthopaedic Surgeon Says
“The ROSA system allows me to execute the surgical plan I’ve developed based on each patient’s imaging, rather than adapting during surgery to what I find. This doesn’t change my approach to patient selection or rehabilitation—it gives me better tools to achieve the alignment and balance I’m aiming for. Patients often ask whether the robot performs the surgery. I explain that I make every decision and perform every cut. The technology ensures my execution matches my intention.”
Putting This Into Practice
- Obtain preoperative imaging: If your surgeon uses CT-based planning, you’ll need a knee scan several weeks before surgery. This allows adequate time for 3D model construction and surgical planning.
- Review the surgical plan: During preoperative consultation, your surgeon can show you the virtual knee model and explain planned implant positions, expected alignment correction, and anticipated outcomes.
- Arrange postoperative support: Recovery requirements are identical to conventional knee replacement. Plan for assistance at home during the initial recovery phase and schedule physiotherapy to begin within days of surgery.
- Prepare your home environment: Remove tripping hazards, arrange commonly used items at accessible heights, and consider installing temporary grab bars in bathrooms.
- Optimise medical conditions: Blood pressure, blood sugar, and any other chronic conditions should be well-controlled before surgery. Discuss medication adjustments with your medical team.
When to Seek Professional Help
- Knee pain limits daily activities such as walking, climbing stairs, or rising from chairs.
- Stiffness that does not improve with movement or prevents full bending and straightening
- Knee swelling that persists despite rest, ice, and anti-inflammatory medication
- Grinding or catching sensations during knee movement
- Knee deformity that has progressed over time
- Night pain that disrupts sleep
- Previous treatments, including physiotherapy and injections, no longer provide relief.
Commonly Asked Questions
Does robotic surgery mean a shorter hospital stay?
Robotic surgery is often combined with enhanced recovery techniques, which may help reduce pain, support faster recovery, and potentially lead to shorter hospital stays. However, discharge timing depends on multiple factors including pain control, functional recovery, and the availability of home support. Individual experiences vary, and your surgical team will determine the most appropriate hospital stay duration based on your specific recovery progress.
Will I set off metal detectors after a knee replacement?
Most knee implants contain enough metal to trigger sensitive detectors. Airport security staff are accustomed to this. You may request a card from your surgeon documenting your implant, though this is rarely required. The implant will not interfere with MRI scans performed at appropriate settings.
How long do robotic knee replacements last?
Implant longevity depends on multiple factors, including patient activity level, body weight, implant design, and surgical technique. Modern knee replacements typically function well for many years or longer.
Is robotic surgery more painful than conventional surgery?
The incision and bone preparation are similar between techniques, so pain profiles are comparable. Pain management protocols are identical for both approaches.
Can all orthopaedic surgeons perform robotic knee replacement?
Surgeons require specific training and credentialing to use ROSA technology. The system has a learning curve for efficient use, though the fundamental surgical skills translate from conventional knee replacement experience. Ask your surgeon about their training and case volume with robotic assistance.
Next Steps
Robotic knee replacement combines surgeon expertise with computer-assisted precision to achieve optimal implant positioning and soft-tissue balance. When conservative treatments no longer provide adequate relief, evaluation by an orthopaedic surgeon can determine whether joint replacement is appropriate.
If you’re experiencing persistent knee pain, stiffness, or deformity affecting your daily activities, an orthopaedic surgeon can evaluate your condition and discuss whether robotic knee replacement is appropriate for your situation.
