Everything You Need to Know About 3D-Printed Knee Replacement

The process of creating objects with materials like plastic, ceramic, or metal using three-dimensional (3D) model data is known as three-dimensional printing. These days, a lot of orthopedic implant manufacturing uses this technology. It is an advancing technology that has the potential to create patient-specific instruments and implants for arthroplasty, considering individual anatomical variations and defects. This process involves using materials such as plastic, ceramic, or metals to construct objects based on three-dimensional model data. Unlike previous technologies where materials were carved into 3D objects, 3DP has become more sophisticated with technological advancements.

The widespread application of 3DP in various healthcare branches, including complex trauma and orthopedics, has grown significantly. 3D models serve as visual and tactile aids for surgeons to study complex cases and plan procedures before surgery. This includes determining implant size, the quantity and type of graft needed, osteotomy site, and rehearsing the procedure on models to minimize intra-operative obstacles and risks. The technology is also valuable for training surgeons and educating patients about planned surgeries. In orthopedic surgery, a combination of plastic or metal is currently used to manufacture 3D-printed knee and hip implants.

3DP has become widely accessible, benefiting various orthopedic disciplines such as scoliosis correction, complex intra-articular trauma cases, pediatric deformity correction, osteotomies, custom prostheses and braces, as well as arthroplasty. The ideal implant in arthroplasty should be well-fitted and have a prolonged lifespan. In knee arthroplasties, precise femoral and tibial cuts are essential for soft tissue balancing, implant positioning, and overall femorotibial alignments.

Traditional surgeries heavily rely on the expertise and skill levels of the operating surgeon, with the high scope for human errors. Even slight variations in determinants like implant positioning could lead to suboptimal outcomes. Therefore, there is a demand for technical improvements in all aspects of surgery. Technical modalities like 3D-printed knees that enhance planning and reduce intra-operative errors are highly efficient, especially in challenging cases such as revisions or patients with poor bone density and bone defects. This article will provide you an insight to developments and current status of 3DP in the field of knee arthroplasties or replacement surgeries.

It is possible to create 3D printed knees. Since 3D printing cannot currently be used to create a functional human knee, the technology has been utilized to make prosthetic limbs or knee implants. Since these implants are custom-made to fit each patient's unique anatomy, they are more precise and specific than conventional off-the-shelf knee replacements.  A CT or MRI scan or other contemporary imaging technique is used to create a digital replica of the patient's knee joint. The 3D-printed implant's design and production are utilized in this model. This technology enables improved biomechanics, alignment, and fit. Which improves the functionality as well as efficiency of the knee replacement.

How are 3D-Printed Knees Made?

• The process 3D printed knee manufacturing involves obtaining an initial image of the required design through a 3D CT scan or MRI
• This initial image is then converted it to an STL (standard triangulation language) format, and sent to a 3D printing machine 
• The 3D printing machine then produces the desired model following the STL as well as required set by the surgeon
• Customized designs allow the production of theoretically superior implants that could better integrate with the bone

Advantages of 3D-Printed Knee Replacement

• 3D printed knee replacement offers several advantages over conventional knee replacement techniques. Here are a few key benefits:
• One of the main advantages of the 3D knee replacement procedure is its ability to be customized to the unique anatomy of each patient. Using state-of-the-art imaging methods and computer-aided design (CAD), a patient's knee joint can be evaluated, leading to the creation of a custom implant. Effective alignment, a more appropriate fit, and optimized biomechanics are ensured by this personalisation, which may lead to better long-term outcomes and improved functionality.
• Thanks to the use of 3D technology, the planning and placement of the knee implant can be completed with the appropriate level of accuracy and precision. Surgeons can simulate the procedure and guarantee optimal soft tissue harmony, implant dimensions, and alignment by using a digital model. This also lowers the chance of errors and increases the range of motion as well as stability of the implant.
• Customized fit and better implant alignment can be achieved with 3D knee replacement, potentially extending the implant's lifespan. A better-fitting implant may experience less wear and tear, which lowers the risk of early failure or implant loosening. This could prolong the implant's lifespan and prevent the need for revision surgery.
• Because of the precise alignment and customized fit, there may be fewer soft tissue changes during surgery, which could lead to less discomfort, less inflammation, and faster recovery to normal activities.
• If individuals can see and understand their own digital model, participate in decision-making, and have access to it, their satisfaction and confidence in the procedure could rise.
• This presents opportunities for additional advancements in biocompatibility, implant strength, and the application of cutting-edge technology, potentially yielding even greater benefits for patients.

Disadvantages of 3D-Printed Knee Replacement

• 3D printed knee replacements could be more expensive than conventional off-the-shelf knee implants.
• Not every healthcare facility could have the resources or expertise to use 3D printing. Therefore, the availability and accessibility of 3D knee replacements may vary depending on where you live. 
• Despite being a more recent procedure, surgeons and other medical professionals may need to go through a learning curve when using 3D knee replacement.
• There might still be restrictions on implant design options, despite the amazing customisation benefits of 3D knee replacements. 
• Even though 3D printed knee replacements are showing promising early results, there continues to be a lot to learn regarding the durability and long-term functionality of these implants.
• In the unlikely event that revision surgery is required, a 3D-printed implant could present challenges.

There are following types of 3D Printed Knees on the basis of material used: 

• Titanium alloy 3D printed knees
• Cobalt-chromium alloys 3D printed knees
• Medical-grade polymers  3D printed knees

Success Rate of 3D-Printed Knee Replacement

Patients undergoing joint replacement surgery can now have safer and more durable procedures than ever before thanks to advancements in 3D printing technology and increased use. 3D printing helps in planning and executing more precise and accurate joint replacements. Elderly patients have fewer risks thanks to these technologies, which also improve outcomes and accelerate recovery. Research indicates that with good patient satisfaction, there is a 99% survival rate three years after surgery and a 92% survival rate five years later.

Read More: Knee Replacement Surgery Cost In Delhi

What distinguishes a conventional knee replacement from a 3D-printed one?

The implants used in conventional knee replacement procedures are not manufactured or customized to meet the specific anatomical needs of the patient. There are several distinct dimensions available for these implants. On the other hand, with a 3D-printed knee replacement, the implants are customized based on the patient's knee's CT or MRI images.

Are knee replacements made via 3D printing appropriate for everyone?

3D printed knees are more appropriate and functional for the majority of patients. But, if you are coming for revision surgery for a previously placed 3D printed knee, your doctor might not recommend this type of replacement.

How is knee implant customization done using 3D printing?

The process of 3D-printed knee manufacturing involves obtaining an initial image of the required design through a 3D CT scan or MRI. This initial image is then converted to an STL (standard triangulation language) format, and sent to a 3D printing machine. The 3D printing machine then produces the desired model following the STL as well as the required set by the surgeon. Customized designs allow the production of theoretically superior implants that could better integrate with the bone

Is it possible to modify or replace knee replacements made using 3D printing?

In the unlikely event that revision surgery is required, a 3D-printed implant could present challenges. Therefore, it is difficult to modify or replace knee replacements made using 3D printing.

How much time does it usually take to have a knee replacement using 3D printing?

There is not much difference in operation time between knee replacement using 3D printing and conventional knee replacement. However, the procedure time depends upon the condition and needs of the patient.

Are there any particular hazards or side effects connected to knee replacements made using 3D printing?

Even though 3D-printed knee replacements are showing promising early results, there continues to be a lot to learn regarding the durability and long-term functionality of these implants. The hazards or side effects connected to knee replacements made using 3D printing are the same as that of conventional knee replacement.

Are insurance companies covering 3D printed knee replacements?

Yes, some of the insurance companies covering 3D printed knee replacements under certain policies. Discuss this thoroughly with your insurance provider before going for surgery.

Is it possible to use 3D printed knees for partial knee replacements?

Yes, it is possible to use 3D printed knees for partial knee replacements also. Yes, it depends on the conditions and needs of the patient.