What are the Advantages of Computer-Assisted Orthopedic Surgery (CAOS) Systems?

Computer Assisted Orthopedic Surgery (CAOS)

Oscillating surgical saw blades are used for bone shaping in total knee arthroplasty. In order to facilitate these cutting procedures, cutting guides have been designed for all implant systems. These guides show which area to cut and at what angle. However, it cannot completely prevent the blade from deviation in medial-lateral (inside-outside) direction. (K. Dimitris et al., 2010)In orthopedics and traumatology surgeries, procedures such as cutting, drilling and reaming bones should be performed as precisely as possible. The accuracy of these procedures directly affects the postoperative results. In this article, we’ll try to explain to you Computer Assisted Orthopedic Surgery (CAOS) and its advantages.

Digital orthopedics helps orthopedists to manage the entire surgical procedure. The entire procedure includes preoperative decisions, intraoperative guidance, and postoperative management. Technologies in digital orthopedics include virtual operation planning, computer-assisted navigation in operations, rapid prototype-assisted operations, virtual operations training, and etc. The application of digital orthopedics in clinical practice is shown in Figure 1. (Pei, 2014)

Figure 1. The application of digital orthopedics in clinical practice (Pei, 2014)

What is Computer Assisted Orthopedic Surgery System (CAOS)?

Computer-assisted orthopedic surgery systems (CAOS) used for navigation provide surgeons access to real-time feedback on ongoing surgery by displaying a virtual image of the operating site on a computer device.

For image-based CAOS systems, clinical images containing anatomical information are very important for surgical navigation. These images are used to model bones and to guide surgeons in surgery. The first important element of a CAOS system is the acquisition of clinical images that report the patient’s anatomy and pathology. Such images serve as input data for computer analysis and guide surgeons during the surgical procedure. Data in orthopedics and traumatology are obtained from a variety of sources, including 2D / 3D fluoroscopy, CT (Computed Tomography) scans, and in some cases, MR (Magnetic Resonance) images. (Kubicek, 2019)

Figure 2. Navigation using surgeon-defined anatomy approach. This virtual model of a patient’s knee is generated intra-operatively by digitizing relevant structures. Although a very abstract representation, it provides sufficient information to enable navigated high tibial osteotomy. (Zheng, 2015)

What are the Advantages of Computer-Assisted Orthopedic Surgery (CAOS) Systems?

1) Provides the surgeon with comprehensive data on patient anatomy.

2) It gives the surgeon the opportunity to plan the surgery with the computer-generated model of the area to be operated.

3) It prevents possible errors by allowing the surgeon to access the feedback instantly during the operation.

4) It helps to align the implant correctly and fit the implant properly into the bone.

5) Thanks to the correctly placed implant, it enables the revision time to be delayed.

6) It helps the patient recover quickly with a lower risk of infection and a lower early failure rate.

In 2010, a study of 1000 consecutive CAOS knee replacements was conducted over a five-year period at Mercy Medical Center in Rockville, New York. It has been determined that CAOS procedures result in better leg alignment, less risk of infection, and a much lower early failure rate than traditionally performed surgeries.

Using traditional techniques, the best surgeons have achieved an alignment with a maximum deviation of three degrees between 50% and 80% of surgeries.

In this study, all operations (100%) performed with CAOS for 5 years managed to stay within 3 degrees of deviation tolerance. In addition, early failures and revision operations due to misalignment, instability or aseptic loosening did not occur in the patients studied. ( Vigdorchik, 2017)

You can click on this link to see the cutting, drilling and reaming surgical power tools used in orthopedics and trauma operations.

For more detailed information about CAOS and the studies carried out in this field in the world, you can access the website of the international association called CAOS International here.


The success of the joint replacement surgery is directly proportional to the accuracy of the alignment of the guides required to shape the bone. Providing a smooth surface and preventing bone necrosis in cutting, drilling and reaming operations performed with surgical power tools are important factors for the success of the surgery. However, if the correct alignment of the implant does not occur, it does not matter that other factors have successful results. Researches reveal the benefits of computer-assisted systems for doctors and patients.

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  • Zheng G and Nolte LP. Computer-Assisted Orthopedic Surgery: Current State and Future Perspective. 2015. Front. Surg. 2:66.doi: 10.3389/fsurg.2015.00066

  • Guo-Xian Pei*, Ya-Bo Yan. Current status and progress of digital orthopaedics in China. Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi’an, P.R. China. 2014. http://dx.doi.org/10.1016/j.jot.2014.05.001

  • Jan Kubicek *, Filip Tomanec, Martin Cerny , Dominik Vilimek, Martina Kalova and David Oczka. Recent Trends, Technical Concepts and Components of Computer-Assisted Orthopedic Surgery Systems: A Comprehensive Review. 2019. Sensors 2019, 19, 5199; doi:10.3390/s19235199

  • Jonathan Vigdorchik, MD. The Benefits of Computer Assisted and Robotic Assisted Joint Replacements. 2017.  https://www.hipsurgerynyc.com/blog/the-benefits-of-computer-assisted-and-robotic-assisted-joint-replacements-22395.html

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