Patient-Specific Knee Replacement – Customized Implants Vs Customized Cutting Blocks

If knee discomfort intensifies, interrupts daily activities, or is associated with swelling and redness, it is crucial to consult a healthcare professional. At Complete Orthopedics, our expert team is committed to treating posterior cruciate ligament injuries using tailored approaches and surgical procedures. We strive to understand your symptoms, identify the underlying causes, and recommend suitable treatments or surgeries.

Our facilities are spread across New York City and Long Island, connected to six top hospitals, ensuring access to exceptional knee care. You can schedule an appointment with our orthopedic specialists online or by phone. Learn about the causes and treatments for knee pain and discover when surgical intervention is the best option.

Overview

Total knee replacement surgery has revolutionized the management of knee arthritis requiring replacement surgery. The number of patients undergoing knee replacements has increased drastically over the past decade. A number of young patients are undergoing knee replacement surgeries due to various knee conditions.

Over the past decade, several new techniques and technologies have emerged raising the patient satisfaction bar. Customized implants and customized instruments (cutting blocks) are two such surgical techniques designed to make knee replacements patient-specific. They both allow greater kinematic movement around the artificial knee joint.

The use of custom implants and instruments is associated with greater efficiency of the surgery and a reduction in operative time. The reduction in operative time is linked to decreased risk of thromboembolic disease, reduction in intraoperative blood loss, and decreased risk of infection. The increase in efficiency and kinematics of the prosthetic joint with custom implants and instruments is also linked with decreased need for revision surgeries.

X-ray showing a custom knee replacement.

Customized implants are 3D printed along with customized cutting blocks. The customized implants are made specific to the patient’s natural anatomy of the knee. Unlike generic off-the-shelf implants, these are tailored according to the patient’s biomechanics.

A preoperative CT scan of the patient’s knee and both lower extremities is obtained. A 3D model of the knee anatomy is created with the help of computer software. An assessment of the biomechanical axis of the lower limbs is also made.

Custom 3D printed cutting blocks.

The data is then used to create patient-specific cutting blocks to minimize bone loss and ensure accurate placement of the customized implants. The result is a more kinematic knee and patients may experience a more natural-feeling knee joint.

Another system utilizes customized instruments/cutting blocks without custom-made implants. The patient’s knee CT/MRI images are used to create 3D anatomy and assess the mechanics of the patient’s knees. The resulting cutting blocks are used to make accurate bone cuts and minimize bone loss. The implants used are off-the-shelf implants.

Although the customized cutting-blocks only system does not use customized implants it offers several benefits. The operating surgeons’ choice while fixing the implant is vastly reduced to only one or a few custom sizes.

The operating surgeon may face difficulties during the surgery while balancing the ligaments and structures around the knee. Some of the patients may have contractures of the knee joint where the knee may have a limited motion before the surgery. The surgeon utilizes specific cutting and loosening of the tissue to obtain full movements around the joint.

Intraoperative image showing custom cutting blocks.

The above intra-operative challenges may warrant additional bone cuts and may require additional sizes of the implants to fit the changed anatomy. Off-the-shelf implants come in various sizes that may fit the customized bone cuts.

Both customized cutting blocks and customized implants are aimed towards increasing the efficiency of the surgery and achieving better kinematic results of the surgery. While customized cutting blocks help in accurate cutting of the bone, the customized implants are designed according to the patient’s knee anatomy. Speak with your orthopedic surgeon what type of customized knee surgery is best suited in your case.

Traditional Knee Replacement

In a traditional knee replacement, surgeons use standardized implants that come in a range of sizes. During the surgery, the surgeon shapes the patient’s bone to fit the selected implant. This method has been successful for many years, but it has some limitations. Standard implants may not fit every patient perfectly, leading to potential issues such as discomfort, limited range of motion, and a less natural feeling in the knee.

Customized Knee Implants

Customized knee implants are designed to match the unique anatomy of each patient. This approach involves taking detailed images of the patient’s knee using MRI or CT scans. These images are used to create a 3D model of the knee, which guides the manufacturing of an implant that fits the patient’s bone precisely.

Benefits of Customized Knee Implants:

Better Fit: Customized implants match the patient’s anatomy more closely than standard implants, potentially improving comfort and function.

Natural Movement: A better fit can lead to a more natural feeling in the knee, with smoother and more natural movement.

Reduced Surgery Time: The precise fit may reduce the time needed for bone preparation during surgery.

Faster Recovery: Some studies suggest that patients with customized implants may experience faster recovery times due to the more accurate fit and less invasive bone cutting.

Customized Cutting Blocks

Customized cutting blocks, also known as patient-specific instrumentation (PSI), involve creating surgical guides tailored to the patient’s knee anatomy. Like customized implants, this process begins with detailed imaging of the knee. The 3D model generated from these images is used to design cutting blocks that guide the surgeon in making precise bone cuts. The actual implants used can still be standard sizes, but the bone preparation is more tailored to the patient’s anatomy.

Benefits of Customized Cutting Blocks:

Precision: Customized cutting blocks improve the accuracy of bone cuts, leading to a better fit of the standard implants.

Reduced Surgical Errors: The use of patient-specific guides helps reduce the risk of surgical errors.

Efficiency: These blocks can make the surgery more efficient by simplifying the bone-cutting process.

Cost-Effective: Customized cutting blocks can be a cost-effective alternative to fully customized implants while still offering many of the same benefits.

Comparing the Two Approaches

Accuracy and Fit:

• Customized implants offer the highest level of personalization, as both the implant and the surgical guides are tailored to the patient’s anatomy. This can result in a more accurate fit and natural movement.
• Customized cutting blocks provide improved precision in bone cutting compared to traditional methods but use standard implants. This approach still offers a better fit than traditional knee replacements but may not be as precise as fully customized implants.

Surgical Procedure:

• Both methods start with detailed imaging and 3D modeling, but customized implants involve manufacturing a unique implant for each patient. This can add time to the pre-surgical process.
• Customized cutting blocks simplify the surgical procedure by providing precise guides for bone cuts, potentially reducing surgery time and complexity.

Recovery and Outcomes:

• Studies suggest that patients with customized implants may experience quicker recovery times and better long-term outcomes due to the improved fit and function of the implant.
• Patients using customized cutting blocks also benefit from improved surgical precision, which can lead to better outcomes and faster recovery compared to traditional knee replacement

Conclusion

Advancements in knee replacement technology have made it possible to tailor the procedure to individual patients through customized implants and cutting blocks. Both approaches offer significant improvements over traditional knee replacement methods by enhancing the accuracy of the surgery and the fit of the implants. Customized implants provide the highest level of personalization and potential benefits, while customized cutting blocks offer a cost-effective and efficient alternative. Patients should work closely with their surgeons to determine the best option based on their specific needs, anatomy, and recovery goals.