Robot-Assisted Partial Knee Arthroplasty: Joint Preservation and Compartmental Resurfacing

Preservation Arthroplasty for High-Proprioception Partial Knee Replacement

Partial knee arthroplasty is a joint-preserving resurfacing technique designed for localized arthritis. Under the surgical direction of Dr. Saminathan Suresh Nathan, the protocol prioritizes the retention of native cruciate ligaments (ACL and PCL) and healthy compartments to maintain physiological proprioception. This approach addresses the historical failures of partial knee replacements, which were largely due to inaccurate manual placement and excessive bone resection.

The Evolution of Robotic Navigation

Traditional navigation systems were frequently "imageless," relying on theoretical norms rather than patient-specific anatomy. As noted in our Computer-Assisted Knee Arthroplasty audit, using Western normative data for Eastern body types often leads to mechanical failure. Recent data confirms that traditional navigation-assisted surgery does not significantly improve long-term outcomes for total knee replacements.

The MAKOplasty system differs by utilizing a CT-based workflow:

Customized Modeling: A mandatory preoperative CT scan creates a 3D model, allowing for patient-specific planning.
Intraoperative Registration: The surgeon registers physical anatomy against the digital model.
Haptic Control: The robotic arm ensures surgical cuts remain within predefined parameters, preventing accidental violation of healthy bone or soft tissue.
Cartilage Mapping: Unlike CT scans which only see bone, the surgeon manually maps the cartilage surface during the procedure, ensuring the implant fits flush with the joint surface.

Surgical Considerations

Ligamentous Integrity: Retention of the ACL and PCL is mandatory to maintain the native kinematic feel.
Precision Inlay: The robot utilizes a burr rather than a saw. This allows for an "inlay" implant where mostly cartilage and minimal bone are removed, sculpting the defect to the exact dimensions of the device.
Recovery: Reduced surgical trauma and bone removal facilitate faster recovery compared to traditional total knee arthroplasty.

Clinical Utility and Future Outlook

The technology has demonstrated a significant improvement in the accuracy of partial joint replacements. We prioritize this approach for patients with:

Unicompartmental Arthritis: Arthritis confined to a single area (medial, lateral, or patellofemoral).
Ligamentous Loss: Can be combined with simultaneous ligament reconstruction.
Biological Preference: It represents a more definitive and cost-effective alternative to stem-cell therapy in the older patient.

Table. This is a summary of the essential differences between MAKOplasty using the RIO robot and other forms of robotic and non-robotic surgery.

Figure 1. In the pre-operative planning stage, CT scan data is used to recreate an accurate model of the patient in the computer program. This allows the optimal positioning of the tibial (a) and femoral (b) component in virtual space. The tibia is that matched onto the real patient by a series of dots (c) and with that we are able to determine how it would function in real life.

Figure 2. This video of an actual case in progress shows the fine cuts that are done in the MAKO system using the RIO robot. Towards the end, the actual procedure is highlighted and shows the minimal precise movement required to achieve these highly accurate cuts. These cuts are more like a sculptors tool rather than the more crude saws and chisels that are used in traditional knee replacement surgery.

Figure 3. The system allows a very accurate matching of the fit in the knee. The bars in the top right corner (a) show the play in the knee in millimeters. In (b) the femoral component is accurately placed and matches the pre-operative simulation in figure 1 above. This is possible because the system actually matches not only bone through the CT image but also cartilage (yellow areas in C). It is co accurate that if bone is removed less than a millimeter in would stop burring and show up in red.

Figure 4. We are proud to be able to bring this service to our patients having been trained by the original team of surgeons in MAKO in the United States and credentialed to perform the procedure in Singapore.

Figure 5. The essential steps in performing a MAKOplasty knee replacement are pre-planning, registration of bone, ligament tension and cartilage, confirmation and milling of bone. It transforms the way we think about knee replacements in being more patient and less implant-centred.

Figure 6. Ever thought of what's in store in a knee replacement procedure? We present here a comparison of a knee replacement with (left panel) and without (right panel) a tourniquet. We do resort to the latter in the difficult cases of patients with significant vascular risk. On the top panel are the salient steps in MAKOplasty surgery. You will see how there is reduced blood loss and less bone removed in the MAKOplasty procedure.

Figure 7. Afraid of blood? Well we produced this video so you can understand the MAKOplasty procedure better without having to see the blood and cuts!

Clinical Authority and Training

The surgical techniques utilized at this practice are the result of over 25 years of frontline execution in Arthroplasty and Limb Salvage. Having served as an International Trainer and Chairman of the Clinical Competency Committee, we mentored the current generation of surgeons on the strict mechanical principles of precision and soft-tissue balancing. We apply these exact, uncompromising standards to your reconstruction. Learn more about our Academic Distinctions here.

Uncompromising care requires clinical independence. We operate outside standard network panels to ensure your treatment is tailored entirely to your clinical needs, not corporate quotas. Verify your coverage here.

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