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HipMainPageImageComputer Assisted Surgery for Total Hip Replacements

Orthopaedic surgeons may use computer assisted surgery (CAS) technology, also known as surgical navigation, during total hip replacement procedures to help ensure that the implants are properly aligned to the patient’s unique anatomy. Accurate alignment of the hip components is crucial to the overall function of the new hip joint.[1][2] Proper alignment may also help the new joint feel more natural, and enable it to potentially last longer.[3]
Hip replacement surgery involves replacing the femur (head of the thighbone) and the acetabulum (hip socket) with an artificial prosthesis consisting of three parts: a cup (replacing the hip socket), a metal stem (replacing the neck of the thighbone) and a metal or ceramic ball (replacing the damaged head of the thigh bone and linking the cup and stem together).
Stryker’s CAS technology for orthopaedic surgery is an interactive monitoring system consisting of 1.) an infrared navigation camera, 2.) Smart Instruments with light-emitting diode (LED) technology and 3.) a computer with specialized surgical navigation software.

The general premise behind computer assisted surgery is the computer software generates a virtual model of the patient’s hip joint anatomy and that serves as a digital roadmap for the surgeon to follow and carry out the surgical plan. The navigation camera tracks the location and movement of Smart Instruments during the procedure and relays this information to the navigation computer. The software then displays in real-time on the virtual model the exact position of Smart Instruments and implant components in relation to the patient’s anatomy.
In the operating room, Smart Instrument trackers are attached to the patient, so the navigation camera is able to track the location and movement of the patient’s hip joint throughout surgery. In a process called patient registration, the surgeon puts the leg through a series of motions and uses a Smart Instrument pointer to touch off on distinct anatomical landmarks of the patient’s hip. This data is used by the computer software to generate the virtual model of the patient’s hip joint. Once patient registration is complete, the computer software provides the surgeon with valuable information including the angles, lines and measurements of the patient’s unique anatomy and displays the exact location of Smart Instruments and implants in relation to the hip joint…all in real time.

CAS does not replace a surgeon’s skills but provides the surgeon with a comprehensive understanding of the patient’s own unique anatomy and kinematics to help determine proper placement of the implants. This information and guidance is not available with conventional, mechanical instruments. For example, the surgeon will utilize the real-time guidance when placing the artificial cup to make adjustments within a fraction of a degree, helping to ensure the cup is angled properly and the new joint has the stability and range of motion needed for a successful replacement.

In addition to arming an orthopaedic surgeon with valuable information throughout the procedure, CAS has other advantages. CAS allows for enhanced visualization of the anatomy, which is particularly important when minimally invasive techniques are used. This technology further provides the surgeon with feedback and the ability to correct potential misalignment in surgery. It delivers assessments of the patient’s joint stability, range of motion, leg length and leg offset all while still in the operating room.

CAS technology offers a total hip replacement patient several benefits including:

  • With CAS technology, surgeons are able to make precise adjustments to ensure the optimal implant fit, range of motion and joint stability. This may help to reduce joint wear and extend the life of the implant.
  • Stryker’s technology does not require a pre-operative CT scan.
  • CAS may allow for less invasive techniques which have other potential advantages including: smaller incisions with reduced muscle disruption[4] and decreased rehabilitation time.[1]

If you are reading this, chances are you or someone you know might be considering total hip replacement surgery. There are risks associated with computer assisted hip replacement surgery as with any surgery. To read more about the risks associated with total hip replacement surgery you may visit  Be sure to talk to your doctor about what treatment options are appropriate for you and the risks associated.

Common Conditions & Treatment

While hip pain can stem from deformity, trauma or sports-related injury, the most common cause is osteoarthritis, also known as degenerative joint disease.  Based on factors such as age, weight, joint function, and activity, osteoarthritis gradually erodes the hip’s cartilage lining. Eventually, bones begin to rub against each other, resulting in friction, swelling, pain, stiffness, and instability. Read More.

Surgeon Testimonials


Computer assisted surgery in my practice has many benefits. The accuracy that I am able to achieve during surgery is greater and more consistent than previously possible.  Also, the information I am able to retrieve from the computer system about my patient in real time, allows me to make changes to the procedure as I operate in order to improve my results and reduce complications."

Dr. Paul Saadi,
Orthopaedic Surgeon,
Dallas Bone and Joint Clinic
Dallas, TX

Video Resources

Image Gallery

OrhoMap Hip Final Cup InsertionIntuitive software provides surgeons with real-time data on implant positioning helping to achieve optimal results during total hip replacement surgery.

Hip ImageDr. Paul Saadi, orthopaedic surgeon with the Dallas Bone and Joint Clinic, Dallas, TX, uses the Stryker Navigation System to create a virtual model of the patient’s hip anatomy during a total hip replacement surgery. This virtual model provides the surgeon with real-time information about the positioning of Smart Instruments and implants throughout the procedure to aid in the accurate placement of the total hip implant.

OrthoMap HipDuring a computer assisted total hip surgery, the computer software provides the surgeon with detailed information about the patient's hip joint kinematics. The surgeon uses this information to help ensure implant stability, range of motion as well as proper leg length are achieved.


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