Robotic hip replacement surgery can be associated with some very satisfying outcomes. To improve the longevity of joint replacement surgery, there have been attempts to harness newer technologies. The hope is to improve the long-term outcomes after the joint replacement surgery.
It is important to use modern technology to improve postoperative function, decrease postoperative pain, and improve the longevity of joint replacements. Computer-assisted systems and robotics have shown to improve the alignment and the position of the prosthesis. Studies have shown that improving alignment can lead to improvement in postoperative outcomes including longevity of joint replacements.
Computer navigation and robotics were introduced in the joint arthroplasty world to reduce outliers in the placement of components and to improve the accuracy and the precision of component placement. These modern technologies offer a promising future towards improving the outcome of your surgery.
Most studies have shown that these newer technologies do not come without any downsides. The problems are increased cost of equipments and longer operating times.
In addition, using new technology comes with a learning curve and a potential increase in complications during the early period of use. It is the hope with new technologies that despite the increased upfront cost, the eventual decreased risk of complications and the need to avoid future surgeries will be decreased.
For total hip arthroplasty there are two types of computer navigations systems- “imageless” and “image-based” navigation systems.
The femoral stem shown in the image above consists of a plasma porous-coated upper segment. The porous coating aids in bone on-growth after the stem is press-fitted in the femoral cavity.
The rasp is used to prepare the femoral canal to press-fit or cement the prosthetic stem in the canal.
Proper registration is the key to success for “imageless navigation” and also for navigation with “imaging based” systems. Imageless navigation systems rely on intraoperative registration marks in the bone obtained by the surgeon and can introduce inaccuracy because it relies on the patient’s judgement on where the component should be placed.
The advantages of imageless navigation in robotic hip replacement is that the technology is cheaper and there is no radiation to the patient and the setup is very minimal. The systems that currently allow imageless navigation are “OrthAlign” and “HipXpert” and “Intellijoint”. These systems use computers to help to calculate mechanical axis and the orientation in a patient.
They then help to compare the position of the prosthesis compared to the preoperative planning. Fluoroscopic navigation is also similar imageless navigation, but I feel that preoperative imaging will be important part of planning of the procedure and it will help to improve the accuracy of placement of components.
There is no preoperative imaging and no preoperative planning in imageless navigation. Although imageless navigation can help improve the precision of arthroplasty, I mainly use “Image-based” systems for surgical navigation.
Image Based Navigation
In today’s day and era, I feel that image-based navigation utilizing preoperative CT scan is much more accurate way to improve the precision of placement of prosthesis. For robotic total hip arthroplasty, the patient undergoes CT scan prior to the procedure and the entire planning is done before the surgical procedure starts.
The surgeon knows the size of the components, orientation of the components as well as the “off-set” and limb lengths prior to starting the procedure. The procedure is done with constrain from the robot and there is less possibility of moving away from the plan that was made preoperatively for the patient.
Pins are placed into the patient’s pelvis and the array is connected in a manner so that the robotic equipment recognizes the pelvis of the patient and integrates the plan into the computer. The preoperative plan is profiled with the data gathered in real time from the pelvis.
The robotic arm then guides the surgeons hand to do the total hip replacement procedure. The robotic arm guides a surgeon’s hand and this type of robotic assistant is called as a “semiactive” system. The surgeon is the person actually making the cuts and the surgeon’s hand is guided by the robot.
There are two types of robotic surgery assistants; one is fully “active” and the other is “semiactive”. Mako is a semiactive type of robotic system. Robodoc was earlier system in the 1980s that was fully active system.
However, there were increased complications with the system because of injury to the soft tissues around the hip. Today, we use the semiactive system which offers active constrain to the cuts and to the reaming done in the bone.
The surgeon has good control over the process sand there is auditory as well as tactile feedback given to the surgeon based on a boundary created by the surgeon in the computer based on the preoperative planning. Using a robot for drilling the bone permits one stage reaming of the cup (as against going one size after the other) because the surgeon knows exactly the size of the components. There is a good consensus in literature that robotics decrease the outliers while improving the accuracy of component positioning.
There is literature to show that accuracy in size and positioning of components may contribute to better placement of the prosthesis which in turn will affect hip stability, and help with better gait and, therefore help in patient outcomes. There are downsides to using a robot. Surgical time still may be increased, especially in the initial part of the learning curve of the surgeon, especially with registration of the bone that is needed for the robot to pick up the architecture of the pelvis and of the femur.
Robotic systems in addition require upfront financial cost for the robot and also for software increments that happen over time. The potential technical complications could include bone motion that can happen during the registration process, the pins may move and may change the alignment, registration may not be accurate, milling and broaching defects if the robot is not used correctly.
Robotic hip replacement surgery is still in an incipient stage and we are still generating data. I feel it is an useful tool in the orthopedic surgeons armamentarium in alleviating pain in patients suffering hip arthritis. I feel there is still room for improvement in technology for robotics in joint replacement surgery.
The surgical time is still a little bit more than a conventional hip replacement. I feel there is room for improving the dose of radiation that is required for a preoperative CT scan. There is still a room for human error which should be minimized.
If we consider a placement of the pins in the pelvis that is needed, I feel that is additional invasiveness that is mandatory for a robotic hip replacement at the current time. There is also an increased cost of equipment and longer operating room times, which need to be reduced as further research goes into improving the robotics involve in the total joint replacement.
The major advantages that I see in robotic hip replacement are:
- To improve the accuracy of component positioning, improve the off-set and the limb length.
- Decreased radiographic outliers
- Possibly decreasing blood loss
- Possibly decreasing bone that is resected during a hip replacement
- Therefore improving patient reported outcomes
I feel the surgeon should use robotics in joint replacement surgery carefully. This is a useful tool in the orthopedic surgeons armamentarium to improve the accuracy of component placement and in alleviating pain in patients suffering hip arthritis.
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