Seper Ekhtiari MD MSc, Vickas Khanna MD, and Anthony Adili MD Division of Orthopaedic Surgery, Department of Surgery, McMaster University, Hamilton, ON, Canada One of the most promising aspects of robotic‐assisted knee arthroplasty is the achievement of more accurate component positioning by eliminating human error and variability. Thus, it is important to understand if, and by how much, robotic‐assisted surgery improves accuracy. Despite improvements in technology and technique,1 about one in five patients undergoing total knee arthroplasty (TKA) are unsatisfied, usually due to persistent postsurgical pain and stiffness.2 The knee is a complex joint, with simultaneous rotation, pivot, and translation in multiple planes throughout its range of motion.3 As well, proprioception in the knee is an important aspect of balance, gait, and overall lower limb function.4 The ability to precisely determine patient‐specific bone cuts and implant positioning, while preserving native anatomy may help to create a knee that feels and behaves more like the patient’s native knee, thereby resulting in improved satisfaction. Robotic‐assisted surgery has the potential to achieve this level of accuracy. Multiple randomized controlled trials (RCTs) have investigated the impact of robotic‐assisted surgery on the accuracy of final component position. In 2007, Park et al. reported the results of the one of the earliest studies on robotic knee arthroplasty (level I).5 They randomized 72 patients to robotic or conventional TKA. They found no difference in the overall mechanical axis alignment between the two groups, but did find that components placed using the robotic‐assisted technique were significantly more accurate in terms of component axis and alignment. Similarly, Song et al. (level I) randomized 100 patients to robotic‐assisted versus conventional TKA.6 They found no significant difference between the two groups in terms of overall mechanical axis alignment or tibial component positioning between the two groups. Femoral prosthesis alignment in the coronal plane was significantly more accurate in the robotic‐assisted group compared to the conventional group. In addition, there were significantly fewer outliers in terms of mechanical axis alignment in the robotic‐assisted group compared to the conventional group (0% vs 24%, p <0.001).6 Liow et al. randomized 60 patients to robotic or conventional TKA (level I).7 Once again, they reported no significant difference in terms of mechanical axis alignment, but did find significantly higher rates of coronal plane outliers and femoral notching in the conventional group. In addition, the robotic‐assisted group had significantly more accurate restoration of the joint line compared to the conventional group (3.2% shift vs 20.6% shift, p = 0.001).7 The same appears to be true for unicompartmental knee arthroplasty (UKA). Bell et al. (level I) randomized 139 patients to conventional or robotic UKA. They found that there were significantly fewer errors in component positioning for all components and in all planes.8 Overall, level I evidence suggests that robotic‐assisted knee arthroplasty is significantly more accurate than conventional surgery in terms of component positioning, but it does not affect overall mechanical axis alignment.5–8 There are limitations in postoperative alignment assessment using only plain radiographs, as these measurements are affected by lower limb loading, rotation, and flexion angles. Importantly, most studies report significantly fewer outliers in terms of component positioning with robotic surgery compared to conventional surgery.6,7 Further, most clinicians’ assessments of TKA alignment are based primarily on the coronal plane with less attention given to sagittal plain alignment. Robotic‐assisted surgery may be particularly important in patients with significant deformity or bone loss. While conventional surgery may still allow the achievement of an acceptable mechanical axis, accurate component positioning is significantly more difficult in these patients due to the loss of normal anatomical landmarks. With robotic‐assisted surgery, there is the potential for less invasive, more tissue‐friendly, and more patient‐specific surgical techniques. Do these technical improvements then translate into the potential for patients to experience faster postoperative recovery and better functional outcomes? It is important to understand if this potential is borne out in clinical practice. As with any new healthcare intervention, it is crucial to understand the impact on patient outcomes. Robotic‐assisted prostatectomy is one of the first widely used robotic surgical procedures, and has shown promise for improving patient‐important outcomes. A recent meta‐analysis found that robotic‐assisted prostatectomy was associated with better outcomes in terms of blood loss, nerve injury, urinary incontinence, and erectile dysfunction compared to open or laparoscopic surgery.9 As well, studies of minimally invasive surgery across different surgical specialties have consistently demonstrated lower levels of postoperative pain and faster recovery with less invasive techniques.10–12
42 Robotics in Total Knee Arthroplasty
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Top three questions
Question 1: In patients undergoing knee arthroplasty, does robotic‐assisted surgery result in more accurate component positioning compared to conventional knee arthroplasty?
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Available literature and quality of the evidence
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Resolution of clinical scenario
Question 2: In patients undergoing knee arthroplasty, does robotic‐assisted surgery result in improved patient‐centered outcomes compared to conventional knee arthroplasty?
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