Long-term results of computer-assisted TKA show low revision, reoperations rates
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Long-term results showed computer-assisted surgery used in 1,048 patients who underwent total knee arthroplasty was associated with average alignment of 1.52° varus and Kaplan-Meier survivorship of 98.34%, a presenter said.
At the Orthopaedic Research Society Annual Meeting, Mary Bayers-Thering, MS, MBA, research manager in the department of orthopedics at Kaleida Health/Buffalo General Medical Center in Buffalo, New York, presented patients’ minimum 5-year results after computer-assisted TKA procedures performed between October 2001 and December 2010.
“The reoperation rate in our large consecutive series was 1.38%. Most reoperations done were manipulations under anesthesia. Our revision rate was also low. These results help demonstrate that the use of the computer helps place our components in good position,” she said.
The revision rate for these computer-assisted TKA cases was 1.7%, which, according to the researchers’ abstract, is lower than what is reported in the registries and in the literature.
Patients had an average age of 66 years and average BMI of 33.6 kg/m2. About 94% of patients had a diagnosis of primary osteoarthritis and about 94% of patients received a cemented cruciate-retaining prosthesis, according to the abstract.
Concerning alignment, Bayers-Thering said investigators only measured 475 long, standing weight-bearing radiographs, which she noted as one weakness of the study. Nevertheless, “81.3% of the X-rays were either neutral or plus or minus 3°. The average alignment was 1.52° varus,” Bayers-Thering said.
In addition, she said patients whose knees exceeded 8° varus or 8° valgus knees were limited to 2.32% and 0.84%, respectively.
Other study weaknesses included the absence of a control group of patients who underwent TKA without computer assistance and longer follow-up, Bayers-Thering said.
She told Healio Orthopedics she was on the research team in Buffalo when Kenneth A. Krackow, MD, developed a TKA navigation system. He performed the first case with it in 1997.
“In 2001, he started using a commercial system he helped develop. Move to 2021 [and] we now have long-term data to support the use of navigation for total knee arthroplasty ... The navigation system allows our surgeons to keep revisions and reoperation rates low while assisting in good component placement. We now know the navigation system is providing better longevity and survivorship for our patients,” she said.
Perspective
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Krackow and his research team should be commended for such a robust single-surgeon report on his computer-assisted orthopedic surgery (CAOS) TKA experience. The 1.7% revision rate at 8.6 years demonstrated superior survivorship vs. Australian registry CAOS reports of 4.6% at 9 years and, more recently, 7.4% at 15 years. It also outperformed the 4.9% revision rate at 5 years that Antonios and colleagues noted in a Medicare-based study. The current study exhibits intriguing advantages compared with such registry studies, as many inter-surgeon variables were controlled by one surgeon.
The next generation of CAOS, collectively noted as robotic-assisted, allows for similar precision to hit a given alignment target reproducibly. As alternative alignment philosophies emerge, like constitutional varus, surgeons will have to follow similar survivorship trends as this important variable can be a moving target. However, the question of whether a computer assistant can benefit a surgeon in mechanical alignment, reproducibility and survivorship seems further validated by studies like that of Krackow.
References:
Antonios JK, et al. J Am Acad Orthop Surg. 2020;doi:10.5435/JAAOS-D-19-0054.
de Steiger RN, et al. J Bone Joint Surg Am. 2015;doi:10.2106/JBJS.M.01496.
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