Computer-assisted hip replacement

Hip arthroplasty, as it is officially known, involves the replacement of the ball and socket joint — the ball is the round-tipped, uppermost portion of the femur, and the socket, known as the acetabulum, is a forward-positioned, cup-like indentation in the pelvis. Hip arthroplasty has been practiced worldwide for decades, and has been refined to the point where hundreds of thousands of people who undergo it every year are returning to a life of pain-free mobility.

During the procedure, the surgeon removes this top portion of the femur, replacing it with a metal stem with a ball on one end. He also frequently replaces the acetabulum with a metal and a polyethylene (plastic) cup.

The new solution

Computer-assisted surgery helps surgeons obtain the most accurate implant alignment and position by providing them with an advanced convergence of multiple medical technologies. Smith & Nephew’s computer-assisted hip replacement software helps surgeons visualize bony structures beyond what they can easily see through the incision and it helps them take critical measurements throughout the procedure that are not possible without the assistance of computers.

How it works

Before beginning the procedure, the surgeon uses the computer to locate specific anatomic landmarks and to take critical measurements of the patients anatomy. Once the computer has this basic information, it can track the precise position of the patient’s leg and pelvis, the implant, and the surgeon’s instruments at all times during the procedure.

Throughout the procedure, the computer provides constant feedback and information to the surgeon. Do not fear; your surgeon is in charge and does the work. The computer simply puts together all of the information coming in from the patient and the instruments and tells the surgeon when he has achieved his desired placement.

Given that every patient’s bone geometry is different and a patient’s physical position on the operating table may change during the procedure, this level of real-time, patient-specific, computer-guided accuracy is unprecedented in the history of hip replacement surgery.

Patient Benefits

A surgeon armed with these tools has the potential to achieve better outcomes. And as computer-assisted total hip replacement surgery evolves, surgeons will be better able to perform less invasive procedures due to the enhanced visualization of the surgical site.

Already, many surgeons have reduced the length of the required incision by as much as 75-percent without the assistance of computer guidance. However, by incorporating Smith & Nephew’s exclusive software and instruments, your surgeon can see better when using this less invasive incision while increasing the accuracy and overall success of the procedure.

A smaller incision made during hip surgery means less muscle is cut and less blood is lost. In turn, this leads to shorter hospital stays and shorter rehabilitation for patients. The benefits to the patient include:

  • The increased visualization provided by the procedure facilitates minimally invasive surgery. This means a shorter scar, less physical therapy and a faster return to your normal life
  • Precise alignment and placement of the implant may extend its lifespan by reducing uneven wear, thus preventing future corrective surgeries
  • Precise placement of the acetabular component may help reduce the risk of post-operative dislocation, and more accurate placement contributes to better long-term implant stability and increased range of motion

The Equipment


The Arrays

“Arrays” are metal prongs with small reflective spheres at their extremities. These devices attach to the surgical instruments and to the patients pelvis. Once they are fixed in place, their positions in space are tracked throughout the procedure. That way, the computer will know exactly where the instruments are in relation to the patient’s bones, based on where the spheres are at any given second.

The Camera

The camera emits infrared light that reflects off the spheres connected to the arrays. It collects this reflected infrared light, and sends the information about the location of the source of the reflection (the spheres on the arrays) to the computer.

The Computer

The computer receives information about where the spheres are in space, and combines that data with three-dimensional virtual images of the orthopaedic implants and surgical instruments.

The Software

The software displays the virtual images of the instruments, implants, and bones on the computer screen, and guides the surgeon through each step of the procedure. The software alerts the surgeon when the instrument is in the most accurate position to make the ideal cut. Also, it helps the surgeon determine where to best position the acetabular component in the pelvis.