Augmented reality in total knee arthroplasty: Balancing precision, promise, and challenges in surgical innovation

Abstract

Augmented reality (AR) is a technology that superimposes digital information onto real-world objects via head-mounted display devices to improve surgical finesse through visually enhanced medical information. With the rapid development of digital technology, AR has been increasingly adopted in orthopedic surgeries across the globe, especially in total knee arthroplasty procedures which demand high precision. By overlaying digital information onto the surgeon's field of view, AR systems enhance precision, improve alignment accuracy, and reduce the risk of complications associated with malalignment. Some concerns have been raised despite accuracy, including the learning curve, long-term outcomes, and technical limitations. Furthermore, it is essential for health practitioners to gain trust in the utilisation of AR.

Key Words: Augmented reality; Total knee arthroplasty; Orthopedic; Surgical precision; Postoperative rehabilitation

Core Tip: Augmented reality (AR) revolutionises total knee arthroplasty by enhancing surgical precision, improving prosthesis alignment, and reducing complications. It also aids in postoperative pain management and rehabilitation, offering immersive experiences that improve patient outcomes. However, challenges such as a steep learning curve, device limitations, and unknown long-term efficacy need to be addressed for broader clinical adoption. Despite these limitations, AR promises to advance orthopedic surgery and patient recovery.

TO THE EDITOR

In the past decade, orthopedic surgery has witnessed a paradigm shift towards digital and precision medicine, driven by the growing demands for improved post-operative quality of life after joint replacements. Augmented reality (AR), emerging as a powerful tool, has gained growing interest in total knee arthroplasty (TKA) procedures. The article by Sakellariou et al[1] comprehensively evaluated the Knee+™ AR navigation system experience in a TKA context. Since the 20^th century, orthopaedic surgeons' interest in computer-assisted systems has been increasing day by day, and they are eager to achieve more satisfactory surgical results through the use of AR, so this study is timely and provides an important reference value for the application of AR technology in orthopedics.

The number of knee replacement surgeries is steadily increasing, with approximately 1 million procedures performed annually in the United States[2]. However, An average rate of 10% to 20% of patients remain partially dissatisfied with their postoperative outcomes[3,4]. Integrating AR into joint arthroplasty represents a significant advancement in orthopedic surgery. It is well known that many complications after TKA are caused by non-optimal knee joint balance in the postoperative period. AR systems provide real-time visualisation of anatomical structures, enabling surgeons to improve the precision of surgical operations, shorten operative time, and improve biomechanical angulation and alignment-specifically ensuring optimal positioning of joint prostheses and restoring proper lower limb mechanical axis[5]; thus, this technology can address long-standing challenges in TKA, including malalignment, implant loosening, and postoperative complications. Integrating AR into TKA is expected to shorten prolonged hospital stays and increase hospitalisation costs due to adverse effects such as postoperative pain and soft tissue imbalance; in addition, many patients have difficulty accessing traditional rehabilitation care after TKA due to mobility issues and distance from healthcare facilities, and AR-based telerehabilitation can address the difficulty in implementing postoperative rehabilitation for patients[6], and reduce the time and financial cost, thereby reducing the financial burden on both patients and the healthcare system.

WHY AR MATTERS IN TKA

Numerous studies have demonstrated that AR systems possess unique advantages, particularly in achieving high precision in prosthesis alignment and mechanical axis restoration. The mechanical axis refers to a straight line connecting the center of the femoral head to the center of the ankle joint. In 2019, a single-center pilot study by Tsukada et al[7] found that the AR-KNEE system could provide reliable accuracy for tibial resection in the coronal, sagittal, and rotational planes during TKA. In 2021, they further confirmed that, compared to traditional intramedullary guides, AR-based navigation systems enable surgeons to perform distal femoral osteotomy more accurately during TKA[8]. These findings are also supported by Bennett et al[9]. Compared to conventional techniques, AR-assisted TKA significantly reduces alignment errors[10,11], shortens surgical time[12], and achieves precision comparable to robot-assisted TKA[13] while being more cost-effective and time-efficient[14].

In addition, the application of AR has been proven effective in postoperative pain management for TKA, effectively alleviating patient anxiety. It is well-known that severe acute pain following knee replacement surgery is a widespread yet underestimated issue[15]. Wearing AR devices provides patients with immersive and multisensory experiences, diverting their attention from pain, effectively regulating pain management, and improving balance in patients with knee pain[16], enhancing early postoperative quality of life[17].

Furthermore, AR integrates well with postoperative rehabilitation, improving patient recovery outcomes. A randomised controlled trial divided TKA patients into AR and conventional rehabilitation groups, with both groups undergoing 12 weeks of rehabilitation training. The study concluded that AR-based rehabilitation for TKA patients resulted in higher satisfaction, significant functional improvement, and enhanced quality of life, making it a viable alternative to traditional rehabilitation[6]. Compared to conventional rehabilitation methods, AR-based rehabilitation training is more engaging, effectively motivating patients, and beneficial for the restoration of knee structure and function, demonstrating broad clinical application prospects[18]. A randomized controlled trial by Su et al[19] reached similar conclusions, showing that AR-enhanced rehabilitation within the first month post-TKA improved pain, function, and anxiety compared to traditional rehabilitation. However, in contrast to previous findings, Su et al[19] noted that AR-based rehabilitation did not improve postoperative quality of life. Nevertheless, the overall benefits of AR for TKA postoperative recovery are undeniable. To better contextualize the role of AR in TKA, we present two Tables (Tables 1 and 2)[6-9,19].

Table 1 The comparison between commonly used techniques in joint replacement.

	Augmented reality	Surgical robot	Traditional navigation
Accuracy	High precision, real-time visualization, close to robotic levels	Extremely high precision, relies on robotic arm and algorithms	Moderate precision, heavily dependent on surgeon experience
Cost-effectiveness	Lower cost, affordable equipment, faster recovery	High cost, expensive maintenance, suitable for high-budget centers	Moderate cost, longer surgery and recovery times
Learning curve	Steep but easier than robotic systems	Very steep, requires mastering complex operations	Low difficulty, mature and easy to learn
Clinical adoption	Gradually increasing, limited by device performance and acceptance	Low adoption, mainly in large hospitals and complex cases	Widely adopted, but limited in precision and efficiency
Surgery time	Shorter, with real-time guidance improving efficiency	Longer, due to robotic setup and calibration	Moderate, requiring intraoperative adjustments
Postoperative recovery	Faster recovery, less trauma, higher satisfaction	Faster recovery, but higher financial burden	Slower recovery, more trauma
Technical limitations	Limited battery life, potential neck fatigue, lack of long-term data	High cost, complex maintenance, limited flexibility	Depends on preoperative imaging, limited real-time adjustment
Future potential	High, with artificial intelligence, 5G, and augmented reality integration, broad applications	Significant for complex surgeries, but limited by cost	Limited, likely to be replaced by augmented reality and robotics

Table 2 Summary of key studies on augmented reality-assisted total knee arthroplasty.

Ref.	Study design	Sample size	AR system	Key focus	Main findings
Tsukada et al[7], 2019	Single-center pilot study	10	AR-KNEE	Tibial resection accuracy	AR provided reliable accuracy in coronal, sagittal, and rotational alignment
Tsukada et al[8], 2021	Prospective controlled trial	74	AR-KNEE	Distal femoral osteotomy accuracy	AR enabled more accurate osteotomy compared to conventional intramedullary guides
Bennett et al[9], 2023	Prospective study	20	AR-AN	Coronal component alignment	Low rate of component malposition in the coronal plane
Su et al[19], 2023	A systematic review and meta-analysis	-	AR-based rehabilitation vs conventional	Pain, function and anxiety	AR-based rehabilitation improved early pain, function, and anxiety
Shim et al[6], 2023	Randomized controlled trial	56	AR-based rehabilitation vs conventional	Function	AR-based rehabilitation may be useful treatment as an alternative to conventional rehabilitation

AR: Augmented reality.

WHAT REMAINS TO BE IMPROVED

With technological advancements, an increasing number of orthopedic surgeons recognise the benefits of using AR technology in surgery. However, in clinical practice, AR technology also has its limitations. First, the learning curve for surgeons using AR technology is relatively steep[20,21]. The learning curve largely depends on the surgeon’s clinical experience and familiarity with the AR device’s interface and operating protocols. As a result, the early adoption phase may be associated with prolonged operative times and an increased risk of intraoperative errors. Second, prolonged use of AR devices can lead to inevitable neck fatigue for orthopedic surgeons. This physical strain may reduce concentration and contribute to operator fatigue, potentially compromising surgical precision and safety. Third, the current battery life of AR devices is limited, making it impractical for use throughout complex knee replacement surgeries involving severe deformities. Battery depletion during procedures may interrupt visualization, forcing the surgeon to switch to conventional tools mid-surgery, thereby disrupting workflow continuity. Finally, while AR technology has shown promising short-term outcomes in TKA, its long-term efficacy remains unknown. In summary, while AR technology offers significant advantages in precision and postoperative recovery, addressing its limitations is crucial for its broader adoption and integration into routine clinical practice.

Further, the study has several limitations. The sample size of 30 patients is relatively small, and the predominantly female population may limit the generalizability of the findings. Additionally, the study focused on short-term outcomes, and long-term data on implant longevity and patient satisfaction are needed to fully evaluate the system's efficacy.

FUTURE DIRECTION

In the future, the application may exceed the surgeon’s imagination by optimising device performance, lowering weight for long-term use (like glasses), shortening the learning curve, conducting long-term efficacy studies, and promoting interdisciplinary integration. Augmented reality technology is expected to further improve surgical accuracy, reduce recovery time, and lower healthcare costs. The integration of AR with artificial intelligence (AI), 5G networks, and robotic systems is poised to revolutionize orthopedic surgery by enabling (1) Highly personalized preoperative planning through AI-driven anatomical modeling and predictive analytics; (2) Real-time remote surgical guidance via ultra-low latency 5G connectivity; and (3) Enhanced intraoperative adaptability via robotic-AR hybrid control systems. These technological synergies will facilitate precision-tailored interventions and expand the feasibility of complex remote surgical procedures. Furthermore, AR's immersive interfaces significantly improve postoperative rehabilitation and patient education through interactive three-dimensional visualizations and gamified training modules, ultimately enhancing recovery outcomes and satisfaction metrics. In addition, large-scale, multi-center randomized controlled trials with longer follow-up durations and more diverse populations are needed to investigate whether patients with different demographic characteristics derive varying levels of benefit from AR-assisted TKA. Such studies will be crucial in identifying the patient populations that are most suitable for AR-assisted procedures, thereby promoting more personalized and effective surgical care. With continuous technological advancements, AR is poised to become a key driver of digital transformation in the medical field, fostering the comprehensive evolution of precision medicine and intelligent healthcare.

CONCLUSION

AR has emerged as a transformative tool in TKA. Its ability to provide real-time visualisation and address critical challenges such as malalignment, implant loosening, and imbalanced knee joint biomechanics, which is expected to enable precision medicine in orthopedic surgery and improve patient recovery and satisfaction. Despite these benefits, AR technology is limited by several technical challenges that remain to be solved. Future efforts should focus on optimising AR systems, integrating them with state-of-the-art techniques, and being more user-friendly. Overall, the integration of AR into orthopedic workflows represents a promising, albeit evolving, direction in surgical innovation.