Robot-assisted hip replacement and why it's different

Introduction

Hip replacement surgery is not as common as knee replacement surgery in Asians. While patients tend to need hip replacement surgery in cases of osteonecrosis and developmental dysplasia in the East, hip arthritis is more common in the West. The techniques of hip replacement in the East and West are therefore slightly different and speak to different outcome measures. The use of computers in hip replacement surgery in the form of navigation never really took off in a big way. A big reason for this is the generally forgiving nature of the ball and socket joint in the hip as opposed to the complicated bicondylar joint of the knee. In the hip therefore even if the cup or socket is misplaced, it will function well for quite a while before it wears out. Increasingly however, patients and doctors have become aware for the need of better placed cups to ensure their longevity. Certainly, the experience of the surgeon is the most important arbiter of cup positioning although that is not the case with the knee. Nevertheless there are a number of advantages that can be posed by a hip replacement system that uses navigation technology and a robot.


Figure 1. Accuracy of the hip is best thought off in terms of hip centre, leg length and offset. All three of these parameters are programmable pre-operatively to achieve the most optimal implant placement.

MAKOplasty in the hip

In the MAKOplasty system, all these factors have been considered in total hip replacement and so in a sense it's like everything and nothing that has come before. It uses a robot to assist in placing a hip replacement in an accurate manner based on navigation data. Apart from the robot, does it not sound like the "same old stuff"?

Well, firstly the navigation used in MAKO is not the "usual" navigation that is used by most surgeons which is "imageless". In MAKO one needs to undergo a CT scan of the hip. This information is fed into the computer so that measurements on the computer are more accurate and customised to the patient. During the surgery the surgeon then registers the anatomy of the patient with that of the images making the surgery very much more accurate. This level of accuracy is then ensured by the robot which ensures that the surgeon is not able to make cuts outside what is determined to be accurate by the surgeon. In addition to this, the robot is able to deliver the reamers into the hip in a single pass ensuring that the bed prepared to received the cup is crafted with the highest precision- manually driven reamers tend to be slightly oblong.

The implant itself is a toal joint replacement and because the robot ensures accurate tracking of the device, it can be done through a smaller incision making post-operative pain much lesser. It is driven by the robot into the socket and ensures an accuracy of 2 degrees and 5 milimeters. The surgeon is even able to see simulations of this even before the implants go in which allows the most accurate placement of trials and reducing costs of voided non-fitting implants at the time of surgery.

 

Promises for hip replacement in the future

The new technology offered by the MAKO system has resulted in a dramatic improvement in accuracy of placement of hip replacement protheses. This has prompted a number of surgeons to now seriously consider this technology as a viable service for their patients. We are proud to announce that our surgeons at Limb Salvage and Revision Arthroplasty Pte Ltd are now credentialed in the procedure having been trained in the United States by the pioneering surgeons of MAKO. It is our opinion that this technology is best suited to the patient with complex challenges posed by hip arhritis in congenital abnormalities of the hip and in revision surgery or hip replacement surgery after trauma.


Figure 2. The real power in the MAKO system in the hip comes during the surgery which allows a real time appraisal of the critical parameters by making the adjustments and capturing it on the computer. This gives an accuracy unheard of previously. The experienced surgeon may not actually benefit too much from this aspect of the surgery. Nevertheless, the ability to fix a cup after one pass of a reamer is potentially beneficial to all surgeons of all levels of expertise.


Figure 3.  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