Knee replacement surgery helps relieve the symptoms of severely diseased knee joints such as pain, stiffness, instability, or loss of function. In healthy knees, the end of your bones is covered with cartilage that allows the bones to move easily against each other. In osteoarthritis, the cartilage becomes severely damaged or may wear away. In these cases, the bones rub against each other and become worn.
In knee replacement surgery, the worn ends of the joint’s bones and the damaged cartilage are removed and replaced with artificial joints (prostheses).
Taking into consideration your weight, age, activity level, knee size, knee shape, and overall health, your surgeon will choose from several different types of knee replacement surgery and a variety of surgical techniques and prostheses.
Let us take a detailed look at the two main types of knee replacement surgery – total knee replacement and partial knee replacement:
Types of Knee Replacement Surgery
Total Knee Replacement: What does it Involve?
During total knee replacement, the surgeon cuts away the damaged bone and then shapes the healthy bone underneath to fit precisely into the artificial implant.
Procedure
- 1. Making the incision in the front of your knee: The surgeon makes an incision of about 6 to 10 inches long to gain access to the patella (commonly referred to as kneecap).
- 2.Turning the patella (kneecap): The patella will be the first part of your knee that is exposed after making the incision. Your surgeon will rotate the patella to view the area needed to perform the surgical procedure.
- 3.Resurfacing the femur (thighbone) and tibia (shinbone): Your surgeon will remove the damaged cartilage surfaces at the ends of the thighbone and shinbone as well as the underlying damaged part of these bones.
- 4.Implanting the femoral and tibial components: In this step, the surgeon implants the femoral and tibial components of the artificial knee at the end of the resurfaced femur and tibia bones. The surgeon will either use bone cement to seal these metal parts or press fits them. Press fitting refers to implants that are built with coarse surfaces to support the bone in your knee to grow into them, thus promoting natural adhesion.
- 5.Readjusting the patella (kneecap): If the kneecap has also degraded, the surface on its underside may be removed and replaced with a polyethylene implant. Before returning the healthy patella to its original place, your surgeon might need to flatten the patella and fix it with another plastic implant to ensure a proper fit with the rest of your implant
- 6.Finalising the procedure: To ensure that the implant is working properly and the alignment, size and positioning are suitable, your surgeon will bend and flex the knee. After that, the procedure will be finalised by closing the incisions with stitches or staples. The surgery lasts about two hours.
Results
Desired results will be visible during the first year after the knee replacement surgery.
For a comprehensive guide to the timeline for your recovery, click on the link to our article:
Recovery from Knee Replacement Surgery in the UK
According to research studies ( 1), for most people, a successful knee replacement surgery leads to significant improvements in:
- Pain
- Stiffness
- Physical and social functioning
- Vitality
Partial Knee Replacement: What does it Involve?
In this type of knee replacement, only one side of the lower end of the thighbone is replaced along with the corresponding part of the top end of the shinbone that is opposite to it.
Procedure
- 1.Inspection of the joint: Your surgeon will make an incision at the front of your knee and explore the knee’s compartments to verify the damaged area.
- 2.Preparing the bone: The surgeon will remove the damaged bone.
- 3.Positioning the implant: In this step, your surgeon will replace the removed bone with metal coverings that recreate the surface of the joint. The implants are either cemented onto the bone or pressed-fit on it.
- 4.Inserting the spacer: The surgeon inserts a plastic spacer between the two metal components to ensure a smooth gliding surface.
- 5.Finalising the procedure: In order to ensure that the implant is working properly and the alignment, size and positioning are suitable, your surgeon will bend and flex the knee. After that, the procedure will be finalised by closing the incisions with stitches or staples.
Results
| - | Total Knee Replacement | Partial Knee Replacement |
|---|---|---|
| Implant Durability | According to a study, approximately 82% of total knee replacements last 25 years (4) . | Many studies demonstrated that more than 90 percent of partial knee replacements are still functioning well 10 years after the surgery. However, about 10% of these implants have to be exchanged within ten years. |
| Recovery | The surgery and the hospital stay are followed by 3 weeks of a rehabilitation program. You can go back to most activities after 3 months. However, muscle and ligament recovery can take up to one year. | You can return to most activities after six weeks. The rehabilitation treatment only involves outpatient physical therapy. |
| Patient Satisfaction after one year of the surgery | About 80% of the patients who have had total knee replacement would choose this type of surgery again. | About 90% would choose a partial knee surgery again. |
| Risk of infection or loosening of the implant | About 5% have suffered complications in the first year after surgery. | About 3% have suffered complications in the first year after surgery. |
Knee Implants
Knee implants are made up of ceramic material, metal alloys and medical-grade plastic.
These are the following components of knee implants:
- 1.Femoral Component: The femoral component is made up of metal that curves around the end of the femur (thighbone or upper-leg bone). It is grooved so the kneecap can smoothly move up and down against the bone as the knee twists or straightens.
- 2.Tibial Component: This component replaces the top surface of the lower leg (tibia). It is typically made up of a flat metal plate with a cushion of polythene plastic. For better fixation, the metal portion may have a stem that inserts into the centre of the tibia bone. In some designs, there is no metal portion and instead, the polyethylene portion is fastened directly onto the bone.
- 3.Plastic Spacer: This is made of polyethylene and placed between the femoral and tibial components. This substitutes the joint space and meniscus and helps the implant move.
- 4.Patellar (Kneecap) component: If osteoarthritis damages the back of the patella (kneecap), it can be replaced with the patellar component. In some cases, the patella does not need to be resurfaced.
Implant Designs
Implant designs reflect the complexity of the joint and closely mimic the motion of a normal knee. Some implants are designed to preserve the patient’s own ligaments, while others act as a substitute for them.
There are 150 implant designs available on the market today; however, surgeons may have a preference for a particular implant, depending on the individual patient’s knee anatomy.
Currently, the most popular knee replacement prostheses manufacturers are “Zimmer Biomet”, “Stryker”, “DePuy” and “Smith & Nephew”.
| Posterior Stabilized Implants | This design is appropriate for those patients in which the posterior cruciate ligaments (PCL) are removed and part of the implant act as a substitute for the ligaments. Cruciate ligaments manage the back and forth motion of your knee. The posterior stabilized design has components that work together to do what the PCL does. |
| Cruciate-Retaining Implants | This implant is appropriate for those whose PCL is healthy enough. So, the PCL is preserved with this implant and the anterior cruciate ligament (ACL) is removed. |
| Bicruciate-Retaining Implants | With this implant, both the ACL and PCL are preserved. This design is appropriate for those whose PCL and ACL are healthy enough. By preserving both ligaments, the knee will function and feel more like a non-replaced knee. |
| Unicompartmental Implants | These implants are those in which only one side of the knee joint is damaged (partial knee replacement), so the unicompartmental implants can be used to substitute just that side. |
| Fixed-Bearing Implants | In fixed-bearing implants, the plastic of the tibial component is firmly attached to the metal component beneath so that the femoral component can roll on this cushioned surface. |
| Mobile-Bearing Implants | In this design, the polyethylene component can rotate short distances inside the metal tibial tray. This design enables the patients a few degrees of greater rotation. |
Latest Developments in Knee Replacement Surgery
Knee replacement technologies have significantly improved both patient outcomes and cost-effectiveness in the different types of knee replacement surgery. The current advances result in:
- Improved accuracy in implant positioning, limb alignment, implant sizing and reliability
- Less trauma
- Reduced blood loss
- A shorter hospital stay
- Quicker recovery
- Less pain & scarring
- A lower rate of infection
- Lower readmission rate
Below are some of the latest developments in knee replacement surgery:
1. Minimally Invasive Surgery
Minimally invasive knee surgery entails the use of micro-incisions and powerful miniature tools that significantly simplify joint resurfacing. This approach reduces the incision to 3 to 4 inches. The key difference between standard and minimally invasive surgery, is that the kneecap is pushed to the side rather than being turned over. This results in smaller incisions and thus fewer traumas.
2. Mako Robotic Assisted Knee Surgery
The initial maker of Mako Robotic technology, Mako Surgical Corporation, was acquired by Stryker in 2013. Stryker’s goal was to transform the orthopaedic industry.
The United States Food and Drug Administration or FDA approved this technology in August of 2015.
Traditional knee replacement surgery uses information from static imaging such as X-rays, CT scans, or an MRI scan taken before surgery, which allows your surgeon to plan the overall implant and bone alignment.
With Mako robotic-assisted technology, your surgeon combines the “static imaging data” taken before surgery with “dynamic joint motion data” collected during your surgery to truly customize the procedure for each patient.
Procedure
| - | Steps | Description |
|---|---|---|
| 1 | Customized Patient’s Surgical Plan | The first step is patient-personalized surgical planning. A CT scan of your knee is taken before the surgery to develop a 3D virtual model of your joint, to evaluate: Bone configuration Joint alignment Disease severity Surrounding tissues It helps your surgeon to determine the exact size, alignments, and placement of the implant. |
| 2 | Motion assessment | Your surgeon makes an incision in your knee to expose your knee joint. Using Mako robotic software, your surgeon will be able to assess how your joint moves. It helps to adjust the surgical plan if needed. |
| 3 | Preparing the Bone | Your surgeon will guide Mako’s robotic arm to remove the arthritic bone and cartilage. |
| 4 | Positioning the Implant | The implant is placed into the knee joint with high precision. Your surgeon will finalise the procedure after balancing the ligament and joint precisely. |
Mako Robotic Assisted Knee Surgery In The UK
| Hospital Name | City/Town | Consultants | Cost |
|---|---|---|---|
| The Princess Grace Hospital (5) | London |
| £14,670 (6) |
| Bath Clinic (7) | Bath |
| £14,000 |
| The Beardwood Hospital (8) | Blackburn |
| £13,625 |
| The Albyn Hospital (9) | Aberdeen |
| £14,720 |
| The Alexandra Hospital (10) | Cheadle |
| £15,450 |
| The Princess Margaret Hospital (11) | Windsor |
| £13,625 |
| Woodlands Hospital (12) | Rothwell |
| £13,625 |
| Fortius Clinic (13) | London |
| Consultant fees £3,000 (Excluding hospital fees) (14) |
| The Royal Orthopaedic Hospital Private Wing Spire Little Aston Hospital(16) | Birmingham |
| £15,352 |
3. NAVIO Robotic-Assisted Technology
Smith & Nephew, the global medical technology business, launched its NAVIO handheld robotics-assisted technology that was approved by the FDA in 2016.
NAVIO is a computer-guided robot design that is built with open-source hardware and software components. By using open source hardware, research expenses can be reduced thus benefitting the development of the process.
The NAVIO robot targets specific soft tissue anatomy and allows precise robotic drilling of bony surfaces in preparation for the surgery with millimetre accuracy.
| - | Steps | Description |
|---|---|---|
| 1 | Personalized surgical planning | Prior to surgery, the surgeon will create a 3D model of your knee without the need for a pre-operative CT scan or MRI. It helps your surgeon collect anatomic and alignment information about your knee for a precise surgery plan. |
| 2 | Advanced image-free navigation | NAVIO technology uses advanced image-free navigation to develop a virtual reconstruction of the patient’s: Knee anatomy Ligament Tension Kinematic motion This information helps your surgeon to assess your unique cartilage wear, joint shape and soft-tissue balance. |
| 3 | Preparing the Bone | Your surgeon makes an incision in your knee to expose your knee joint. After collecting patient-specific data, boundaries are established for the robotics-assisted hand piece. The hand piece helps the surgeon to remove the damaged-bone surfaces within the defined plan, ensuring precise removal of the bone surfaces and accurate positioning of the implant as intended. |
| 4 | Positioning the Implant | After preparing the site for the prosthesis, the surgeon will precisely position the implant. |
NAVIO Robotic Assisted Knee Surgery In The UK
| Hospital Name | City/Town | Consultants | Cost |
|---|---|---|---|
| The Clementine Churchill Hospital (17) | Harrow |
| £15,045 |
| The London Clinic (18) | London |
| £16,560 |
| Nuffield Health Tunbridge Wells Hospital (19) | Royal Tunbridge Wells |
| £13,093 |
| Spire Bushey Hospital (20) | Bushey |
| £13,130 (21) |
4. CORI Assisted Knee Surgery
Smith & Nephew launched its next-generation CORI surgical system which obtained its FDA approval in February 2020 for both total and unicompartmental knee arthroplasty.
Compared to the NAVIO system, CORI’s new technology has:
- Next-generation cameras that are more than four times faster
- Cutting technology that can handle twice the cutting volume
- Super system that sends precise information about your knee to a robotic-assisted hand piece more than 300 times per second.
- Modular design that can also handle other types of orthopedic surgeries
CORI Assisted Knee Surgery In The UK
| Hospital Name | City/Town | Consultants | Cost |
|---|---|---|---|
| The Highfield Hospital (22) | Rochdale |
| £12,050 to £15,250 |
The above quoted prices are “Guide Prices” and may vary depending on your individual needs.
For a comprehensive guide to the cost of knee replacement surgery in the UK, follow this link to our recent article:
Knee Replacement Surgery: Should you Stick with the NHS or Go Private?
Conclusion
Knee replacement surgery is increasingly become more sophisticated and safe. New developments in the different types of knee replacement surgery are paving the way for millions of people to get benefit from more accurate and precise surgical procedures. Talk with your surgeon to determine which procedure is best for your specific needs.
