Total Shoulder Arthroplasty and the Role of Robotic Surgery Systems

Total shoulder arthroplasty (TSA) is a widely accepted surgical procedure for treating severe shoulder arthritis and other degenerative conditions affecting the glenohumeral joint. The procedure involves replacing the humeral head and glenoid cavity with artificial components, aiming to restore mobility, reduce pain, and improve the patient’s quality of life.

Traditional TSA relies heavily on manual techniques, and implant positioning is critical to achieving successful outcomes. However, challenges such as misalignment, implant instability, and varying patient anatomy have historically made TSA outcomes inconsistent.

Similar to hip and knee arthroplasty, the introduction of robotic-assisted surgery offers an innovative solution. There are many parallels between TSA and hip robotic surgery, particularly in terms of clinical benefits. However, there are unique clinical and technological challenges that differentiate the problem. These challenges include visibility of the bony structures, particularly with the scapula.

Basics of Robotic Surgery in TSA

Robot-assisted TSA utilizes advanced imaging, navigation, enabled instruments, and robotic arms to assist surgeons in planning and executing the procedure to achieve improved accuracy. The integration of robotic technology in TSA aims to enhance both the preoperative planning phase and the intraoperative execution of the surgery.

Preoperative imaging and planning involve CT scans, which generate 3D models of the patient’s anatomy. These models allow surgeons to customize implant selection and positioning before surgery begins. By using the scan data, surgeons can identify any anatomical abnormalities and determine the optimal implant placement, tailored to the patient’s specific shoulder structure and desired range of motion.

During the procedure, intraoperative navigation provides real-time tracking of instruments and anatomical landmarks, ensuring continuous updates to the surgical plan and alignment. The robotic arm, guided by the preoperative plan and real-time data, aids the surgeon in bone preparation and implant positioning. This level of precision helps reduce the risk of implant malalignment, which is a common cause of TSA failure.

Artificial intelligence (AI) and machine learning play an integral role in robotic-assisted TSA. These technologies continuously analyze data from previous procedures, refine surgical techniques, and provide predictive analytics to optimize outcomes. The inclusion of AI helps surgeons adjust their approach dynamically during surgery, leading to improved implant positioning and better long-term stability of the joint.

Studies have shown that robotic-assisted TSA improves glenoid component placement accuracy and significantly decreases the risk of implant malpositioning, one of the leading causes of TSA failure. Early clinical outcome data suggest that reduced intraoperative variability results in better postoperative function and higher patient satisfaction.

Challenges with Robotic Surgery in TSA

Despite the numerous advantages of robotic-assisted TSA, several challenges must be addressed for its widespread adoption.

Cost

One of the most significant barriers is the high cost of robotic surgical systems. Acquiring and maintaining these systems requires substantial investment, limiting their availability to high-volume surgical centres and well-funded healthcare institutions. Smaller hospitals and outpatient surgical centres may struggle to justify the cost of integrating robotics into their TSA procedures.

Unlike hip surgery, TSA is not ‘high-volume’; procedures are rising, but the amortized cost of the robotic system per surgery is significantly more. For instance, dedicated TSA surgeons may perform 80% of surgeries in the US, while general orthopedists perform the other 20%. As such, a general orthopedist may only be doing one per month. It is hard to justify a robotic system costing hundreds of thousands of dollars for this low volume.

Training

There is a steep learning curve associated with robotic-assisted TSA. Surgeons must undergo extensive training to operate robotic systems effectively, which can delay widespread adoption.

Although robotic systems provide enhanced precision, improper use due to insufficient training can lead to complications, negating the benefits of the technology. This is a similar problem to the cost; how can a general orthopedic surgeon climb the learning curve when they perform so few surgeries? And are their hip robotic skills transferable to the TSA application?

Limited Long-Term Clinical Outcome Data

While early studies suggest improved accuracy in implant positioning, more research is needed to confirm whether robotic-assisted TSA leads to better patient outcomes over the long term compared to traditional methods. Robot-assisted TSA has been at least 10 years behind robotic-assisted total hip arthroplasty (THA). As such, clinical data showing the clinical benefits are still being collected and published.

Hospitals and surgical centres must also adapt their workflows and infrastructure to accommodate large robotic systems. Integrating robotic-assisted TSA requires modifications to operating rooms, staff training, and updates to existing surgical protocols, which can be disruptive and time-consuming. Again, for the general orthopedic, if the system is different to their robot-assisted THA system, then how do they swap in and out of the systems effectively?

Key Surgical Steps

In robot-assisted TSA, there are four key surgical steps that the technology should solve for:

1. Glenoid pin insertion

To achieve optimal alignment, carefully position the guide pin on the precise location of the glenoid surface. Once the pin is accurately placed, drill it at the correct angle and depth to ensure into the scapular spine.

2. Glenoid reaming

Place the glenoid reamer over the pin and ream the glenoid surface to achieve the depth required for optimal placement. While it is possible to merge the initial steps of pin insertion and reaming into a single operation, doing so might introduce an excessive number of variables that could compromise the accuracy of the procedure.

3. Humeral head resection

Head resection at the correct angles, both version and inclination.

4. Humeral reaming/broaching

The reamer needs to be guided into and down the humeral shaft at the planned angle and depth until the desired diameter is achieved.

Tracking for TSA

Tracking systems are essential for robotic-assisted joint surgery, providing accurate spatial localization of surgical instruments and anatomical structures. These systems typically use optical markers and electromagnetic tracking to enhance precision.

Optical markers, which can be either passive or active, are placed on surgical instruments and bones. Infrared cameras track these markers in real time, allowing surgeons to see the exact positioning of the instruments relative to the patient’s anatomy.

Electromagnetic tracking, on the other hand, utilizes sensors embedded in instruments to detect their position and orientation relative to a reference frame. Both tracking methods help improve the accuracy of implant placement, reducing the risk of complications such as implant loosening and instability.

Marker placement is the key challenge for a number of reasons.

1. The operating room set-up and the surgeons’ positions can block the camera’s view of optical markers. The two surgeons are standing close together, shoulder to shoulder, beside the patient, close to the patient’s head, and, as such, next to the anesthetist’s drapes.
2. The bony structure of the scapula is not well exposed. The coracoid process and acromion are apparent places to insert the pin or attach a marker clamp, but access to either of these may require a larger incision. Other bony anatomy of the scapula, such as the scapula spine, could be used with any additional ‘stab’ incision. However, the spine may not be wide or deep enough to fix a pin securely. This is a very different problem from the femur, pelvis, or tibia.
3. The humerus is large enough to attach a pin. However, if a pin and array are placed when the humeral is in anatomical position, when the humeral head is dislocated anteriorly or posteriorly, depending on the surgical approach, the marker array would be pointing to the floor.
4. The biomechanics of the shoulder also present an issue. The shoulder joint is ‘floating’ in the rib cage; it is not attached to other bony structures of the torso (excluding the clavicle). When the surgeon performs a range-of-motion assessment, the humerus is manipulated in a wide-angle range. The camera’s ability to track this significant motion is challenging.

The four distinct challenges presented by robotic-assisted total shoulder arthroplasty set it apart from robotic-assisted total hip arthroplasty. Each challenge necessitates a specialized technological solution, making it challenging to adapt an existing robotic system. This uniqueness underscores the need for tailored innovations in robotic assistance specific to the complexities of shoulder surgery.

Key Competitors in Robotic TSA

Medical device companies are increasingly competing in the market for robotic-assisted orthopedic surgery. Several major companies have developed robotic systems designed for TSA and other joint replacement procedures.

Zimmer Biomet

Zimmer Biomet introduced the ROSA Shoulder System, the world’s first robotic assistant explicitly designed for shoulder replacement surgeries. This system supports surgeons in performing both anatomic and reverse shoulder arthroplasty, offering real-time, intra-operative data to control, execute, and validate personalized surgical plans.

In April 2024, Zimmer Biomet announced the successful completion of the world’s first robotic-assisted shoulder replacement surgery using the ROSA Shoulder System at the Mayo Clinic.

Key features:

• It allows surgeons to adapt the system to their preferred workflows, enhancing confidence through an intuitive interface and robotic-assisted procedures.
• CT-based 3D modeling provides a virtual simulation of the patient’s shoulder anatomy.
• Real-time tracking of surgical instruments and robotic arm movement on a high-resolution screen means surgeons can see bone cuts, implant placements, and adjustments in real time, reducing alignment errors.
• A haptic feedback system aids surgeons by displaying positional data, force application, and bone removal metrics, ensuring a precise bone preparation process.

Johnson & Johnson MedTech

Johnson & Johnson MedTech offers the VELYS Robotic-Assisted Solution, initially designed to assist in total knee arthroplasty. The system simplifies surgeons’ workflows by providing a table-mounted robot that resects bones and aligns implants relative to soft tissue without requiring preoperative imaging. While primarily focused on knee procedures, Johnson & Johnson is expanding its robotic platforms to support hip and shoulder surgeries.

Key features:

• AI-driven visualization and real-time kinematic feedback.
• AI-assisted imaging analysis that generates a dynamic 3D map of the shoulder joint, helping surgeons determine the optimal implant position.
• A table-mounted visualization system to track soft-tissue balance and bone preparation through high-definition optical sensors.
• Graphical representation of soft tissue balance and joint stability, allowing surgeons to make data-driven decisions on implant positioning.

Stryker

Stryker’s Mako System is a robotic arm-assisted technology widely used for partial knee and total hip arthroplasty. The system enables surgeons to create a patient-specific 3D model to preplan surgery and assists in bone preparation and implant placement during the procedure. It has been primarily utilized for knee and hip surgeries.

Key features:

• Preoperative CT scans to create a customized 3D reconstruction of the shoulder joint.
• Haptic and visual feedback to ensure precise bone resection and implant alignment.
• High-resolution display shows color-coded mapping of bone structures, implant positioning angles, and cutting depths, reducing surgical variability.

Exactech

Exactech has focused on augmented reality (AR) visualization rather than full robotic assistance for TSA. Their ExactechGPS system combines navigation tools and AR overlays to provide surgeons with real-time anatomical guidance.

Key Features:

• Instead of relying solely on a screen, surgeons wear AR glasses or a display headset to view 3D reconstructions of the patient’s shoulder anatomy in real time.
• The system shows interactive overlays that indicate ligament tension, glenoid orientation, and impingement zones.
• Unlike robotic systems that require large operating room setups, Exactech’s AR approach provides direct visualization without requiring a robotic arm.

Interventional Systems (INS) and IJX Navigation (IJX)

INS and IJX have partnered to develop a compact robotic navigation solution optimized for ambulatory surgery centers (ASCs). This integrated system combines clinically validated miniature technology to address the complexity of shoulder anatomy while providing a small footprint and portability suitable for ASCs. This collaboration aims to make robotic-assisted shoulder arthroplasty more accessible in outpatient settings.

Key features:

• The system uses electromagnetic sensors rather than optical tracking, displaying real-time positional data on an integrated surgical monitor.
• It provides a portable tablet-based visualization, reducing space constraints in the operating room.

In summary, Zimmer Biomet currently leads the way in providing a dedicated robotic system for total shoulder arthroplasty with its ROSA Shoulder System. Other companies, such as Johnson & Johnson and Stryker, offer robotic-assisted solutions primarily focused on knee and hip procedures but are exploring expansions into shoulder surgeries. Innovations from collaborations like Interventional Systems and IJX Navigation indicate a trend toward making robotic-assisted shoulder arthroplasty more accessible across various surgical settings.

Conclusion

Robot-assisted total shoulder arthroplasty marks a significant advancement by enhancing precision, reducing intraoperative errors, and potentially improving long-term clinical outcomes.

For a robotic-assisted TSA system to be successful, it must fulfill several technical and operational criteria. Real-time navigation and tracking are essential for monitoring surgical instruments and anatomical structures with high accuracy, thereby minimizing errors during the procedure.

As robotic TSA technology advances, enhanced visualization capabilities and imaging integration are likely to become critical differentiators, enabling compatibility with CT, MRI, and fluoroscopy for both preoperative planning and intraoperative adjustments.

The system should also allow for surgeon-controlled robotic assistance, enabling surgeons to maintain complete control over the procedure while benefiting from improved precision.

Despite challenges such as cost and training, the ongoing evolution of robotic technology is anticipated to transform TSA into a more precise, efficient, and effective procedure. With major medical technology companies making significant investments in this area, the future of TSA is poised for transformative improvements that will benefit both surgeons and patients.