• Eric Hanyak, PT, DPT

Robotic vs. Traditional Knee Replacements

Total knee replacements -- or total knee arthroplasties (TKA) have become one of the most performed orthopedic surgeries in the world. According to the Agency for Healthcare Research and Quality, in 2017, more than 754,000 knee replacements were performed in the United States. In the PT clinic I treat as many patients after total knee replacements as any other orthopedic surgery. In orthopedic healthcare, total knee replacements are widely regarded as one of the most successful surgeries. The AAOS notes that over 90 percent of replacement knees are still functioning after 15 years.

Knee replacements are most often done when a person’s knee joint develops severe arthritis. This is when the cartilage in the knee joint -- at the bottom of the femur (“thigh bone”) and the top of the tibia (“shin bone”) -- degrades and the joint becomes painful and usually inflamed. Cartilage acts as padding in the knee joint and to decrease friction as the knee moves. When a person loses most of the cartilage in the knee this can be described as “bone on bone” arthritis and can require a TKA. Most of the time this loss of cartilage is due to wear and tear and is described as osteoarthritis. In some cases this can be caused by an inflammatory condition called rheumatoid arthritis or trauma like a motor vehicle accident.

Knee replacement surgery was first performed in 1968. Since then, improvements in surgical materials and techniques have greatly increased its effectiveness. Recently more and more surgeons are utilizing robotic guided surgical techniques and generally with excellent outcomes.

In a traditional TKA the surgeon uses preoperative x-rays, intraoperative anatomical landmarks, and manually positioned alignment jigs to guide bone cutting and implant positioning. These handheld techniques can lead to less reliable alignment-guide positioning, inadvertent sawblade injury to the knee muscles and ligaments, and limited ability to fine-tune the implant positioning. Suboptimal implant positioning may lead to poor functional recovery and reduced implant survivorship. (At this point I should note that I work with many surgeons who have done hundreds or thousands of these traditional TKAs with great clinical outcomes.)

Robotic TKA uses computer software to convert anatomical information into a virtual patient-specific 3D reconstruction of the knee joint. The surgeon uses this virtual model to plan optimal bone cutting and implant positioning based on the patient’s unique anatomy. An intraoperative robotic device helps to execute this preoperative patient-specific plan with a high level of accuracy. The action of the sawblade is confined to the preoperative surgical plan which limits soft-tissue injury and bone trauma.

A 2019 systematic review about robotic total knee replacement found the following:

  • Robotic TKA improves the accuracy of implant positioning compared to conventional jig-based TKA.

  • Cadaveric studies have shown robotic TKA is associated with reduced injury to the soft tissue around the knee compared to conventional jig-based TKA.

  • Robotic TKA is associated with decreased postoperative pain, enhanced early functional rehabilitation, and decreased time to hospital discharge compared to conventional jig-based TKA. However, there are no differences in medium- to long-term functional outcomes between conventional jig-based TKA and robotic TKA.

  • Limitations of robotic TKA include high installation costs, additional radiation exposure, learning curves for gaining surgical proficiency, and compatibility of the robotic technology with a limited number of implant designs.

If you are considering getting a TKA there is clearly a lot of evidence that robotic TKA are effective and in some ways superior to a traditional TKA. That being said, there are many other factors to consider when looking for a surgeon to do your TKA including:

  • Number of TKAs the surgeon has done: in general I recommend surgeons who have done hundreds of TKAs as they are both proficient and efficient in the operation. The less time you are on the operating table, the less opportunity for tissue damage or infection.

  • Relationship with a surgeon: if you have a surgeon you know and trust who uses a traditional technique you are still likely to have excellent outcomes.

  • Proximity to home: if there aren’t surgeon’s in your immediate area who do robotic TKAs you may have to travel for your surgery and pre-op and post-op visits.

Once you've made your decision don't forget the importance of rehab! All of our physical therapists are experts in both pre and post op knee replacement rehab. For more information about what to do once you've made this big decision, reach out to one of our clinics to set up an appointment!

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