Computer‐assisted Orthopaedic Surgery

Abstract

Nowadays, operating rooms can be inefficient and overcrowded. Patient data and images are at times not well integrated and displayed in a timely fashion. This lack of coordination may cause further reductions in efficiency, jeopardize patient safety, and increase costs. Fortunately, technology has much to offer the surgical disciplines and the ongoing and recent operating room innovations have advanced preoperative planning and surgical procedures by providing visual, navigational, and mechanical computerized assistance. The field of computer‐assisted surgery (CAS) broadly refers to surgical interface between surgeons and machines. It is also part of the ongoing initiatives to move away from invasive to less invasive or even noninvasive procedures. CAS can be applied preoperatively, intraoperatively, and/or postoperatively to improve the outcome of orthopaedic surgical procedures as it has the potential for greater precision, control, and flexibility in carrying out surgical tasks, and enables much better visualization of the operating field than conventional methods have afforded. CAS is an active research discipline, which brings together orthopaedic practitioners with traditional technical disciplines such as engineering, computer science, and robotics. However, to achieve the best outcomes, teamwork, open communication, and willingness to adapt and adopt new skills and processes are critical. Because of the relatively short time period over which CAS has developed, long‐term follow‐up studies have not yet been possible. Consequently, this review aims to outline current CAS applications, limitations, and promising future developments that will continue to impact the operating room (OR) environment and the OR in the future, particularly within orthopedic and spine surgery.

Introduction

Operating room technology is in a period of accelerating innovation, in which recent advances have revolutionized preoperative planning and surgical procedures by providing visual, navigational, and mechanical computerized assistance1, 2. The field of computer‐assisted surgery (CAS) broadly refers to surgical techniques involving both surgeons and machines; CAS has allowed for greater precision, control, and flexibility in carrying out surgical tasks than conventional methods have afforded3, 4. The present review highlights key information regarding the nature, applicability, and limitations of CAS. Special emphasis is given to the review of existing, emerging, and promising future applications within the field of orthopaedic surgery.

Computer‐assisted surgery is an innovative technology that enhances surgical guidance. First employed clinically nearly 20 years ago, CAS has since developed rapidly, earning its place as a routine fixture in surgical practice and operating rooms5. CAS was initially developed to locate brain tumors based on a surgical intervention that used a three‐dimensional coordinate system. Since its creation, the field of CAS has expanded its range of functions and applications to include many other surgical subspecialties, leading to the emergence of computer‐assisted orthopaedic surgery (CAOS) 6. In fact, orthopaedic surgery has proven to be particularly well suited for CAS. Over the years, computer assistance has gained wide acceptance for use in a variety of orthopaedic procedures, such as total joint arthroplasties, arthroscopic surgery, spinal surgery, and trauma surgery7.

The success of CAS is partially attributable to the relative ease and accuracy of evaluating bones and soft tissues using diagnostic technologies such as radiography, fluoroscopy, CT scans, and MRI. Using digital X‐rays, CT, MRI, ultrasound, or fluoroscopy, CAS can allow surgeons to more accurately visualize the patient's anatomy on a monitor 8, 9. In addition, CAS may provide real‐time operative views of surgical instruments and their relative positioning with respect to the anatomy of the patient and previously existing implants. The applications of CAS and CAOS are vast, as is their promise; these technologies have the potential to be used as research or training tools, in routine clinical practice, and to pave the way for less or minimally invasive surgical techniques.

Methodology

The searches for descriptors “orthopaedic surgery,” “computer‐assisted surgery,” and “DaVinci System,” in combination with using the Boolean connector “AND” and indicating a year for articles published between 2000 and 2016, yielded 16 results each. Of the 16 results, approximately 9 articles met the inclusion criteria, and after applying the exclusion criteria the selection usually decreased to approximately 6 articles in each database. Three articles per search did not reported detailed descriptions for the computer‐assisted surgery system used and, therefore, were excluded from the selection. As a result, the description of the methodology used to carry out the search, collection, recording, and the refined posterior search was established and is presented in Fig. 1.

Figure 1.

Illustration of the methodology followed to develop this review article as sequential steps. First, a literature search was performed using the descriptors listed above (1), mostly in PubMed, Healio, and Science Direct databases (2). Second, the type of studies reviewed included review articles, original research, and clinical reports (3), which were chosen according to the inclusion criteria (4.1) and exclusion criteria (4.2) defined prior to the start of the search. Finally, the recording of all the articles reviewed was registered chronologically (5), and subsequently the search was refined (6) looking up the references of the articles chosen that met the inclusion and exclusion criteria.

Types of Computer‐assisted Surgery

Computer‐assisted surgery involves technologies that directly participate in surgery as well as systems that do not immediately take part but may assist in the navigation or positioning of instruments5. Specifically, CAS can be categorized into three systems, each with important but distinct functions: (i) passive systems, (ii) semi‐active systems, and (iii) active systems. Passive systems do not perform any surgical actions on patients; instead, they serve a crucial role in assisting surgeons with preoperative planning, making surgical simulations, and with intraoperative guidance. Navigation is the primary mode of passive systems, which may be CT‐based, imageless, or fluoroscopic10. An example of a passive system is Optotrak 3020, an optical system that uses infrared light to garner positional information intraoperatively10 (Fig. 2).

Figure 2.

The optical 3‐D position sensor (Optotrak 3020), used for intraoperative surgical navigation, is an example of a passive computer‐assisted surgery (CAS) technology10.

Unlike passive systems, semi‐active systems perform some actions, such as moving a drill guide sleeve or a cutting jig. However, they do not perform direct surgical actions. For example, Acrobot, a semi‐active system, allows surgeons to control a drill bit using a robotic arm in real‐time. Finally, active systems perform some surgical actions that are programmed preoperatively8. An example of an active system is ROBODOC, which prepares the femoral canal for prosthesis placement based on pre‐surgical plans11 (Fig. 3).

Figure 3.

ROBODOC is an active system of many components (displayed above). The ROBODOC system performs preoperatively‐planned surgical actions and has been particularly useful for placing femoral implants10.

Current Applications

Hip Replacement

Hip replacement, or total hip arthroplasty (THA), involves surgical replacement of the hip joint with prostheses. CAOS technologies for THA range from surgical robots and surgical navigation devices to patient‐specific templates and other types of instruments that allow for speedier, more effective, and safer surgeries. Computerized assistance for THA is particularly useful for ensuring proper alignment of implants. By improving visualization and surgical precision, CAS can help situate implants with respect to one's unique anatomy. Proper alignment of the implants improves the functionality of hip joint replacements and has also been shown to enhance the durability and fit of the new joint12. Specifically, a main positioning concern of THA is malposition of the acetabular component of the implant, which can result in impingement, reduced range of motion, and increased risk of dislocation13. However, computer‐assisted placement of the cup component of the prostheses has reduced the risk of malpositioning and has been proven to be a reproducible, accurate, and better alternative to traditional methods of cup replacement3.

Other functions of CAOS in hip surgery include measuring limb‐length changes and allowing for minimally invasive surgery14. These functions are most often fulfilled with CT‐based and imageless navigation systems, which provide a real‐time virtual model of the surgical field, consisting of the placement of anatomy, instruments, and implants14. CAOS better allows the surgeon to perform the procedures by providing virtual feedback throughout surgery, as well as improving the visualization of the patient's anatomy, which is especially useful for carrying out minimally invasive THA. Minimally invasive approaches, by nature, limit visualization of the surgical field, and thus, their use in THA necessitates computer navigation to assist with component placement. These minimal incision approaches are controversial, but studies have found that their use has not compromised accuracy of component positioning and also that they allow for significantly higher accuracy placement in hip surgery15, 16. Computer‐assisted navigation has also been valuable for obtaining post‐operative leg‐length equality, which is an important outcome measurement for THA success14. Limb‐length inequality has been shown to contribute to stiffness, pain, and early implant failure in addition to being a leading cause of dissatisfaction and legal disputes proceeding THA14, 17.

Patient‐specific templates (PST) and instruments are another form of CAOS that are a lower resource‐consuming alternative to the costlier, more time‐consuming, and spatially‐constraining robotic and navigational CAOS systems. PST, like navigation, can be used for 3‐D preoperative planning and precision surgery10. PST contain a base component, which is placed on the bone surface prior to surgery, and a guide component, which is used to achieve preoperatively planned placement of prostheses or instruments10 (Fig. 4). PST have shown promise for guide wire insertion involved with hip arthroplasty resurfacing as well as with cup placement for THA10.

Figure 4.

A patient‐specific template specific for guide wire insertion may be used in hip arthoplasty10.

Knee Replacement

In order to have a successful outcome for total knee arthroplasty (TKA), the surgeon must achieve a good rotational and translational alignment of the prosthetic components and the limb18. Proper alignment allows for knee stability and sufficient range of motion, providing adequate movement to attain improved quality of life. With regards to the efficacy of CAOS for knee replacement, there is controversy surrounding the outcomes and benefits. The benefits of CAOS have been reported in terms of decreased variance in the prosthesis alignment in total knee replacement (TKR) as well as reduced blood loss. In addition, computer assistance using extramedullary guides has reduced the risk of fat embolisms, which are a major known complication of TKA19. In contrast, the drawbacks include a lengthened duration of surgery by 23% as well as no improvement in infection rates or thromboembolic events20. However, it does appear that CAOS provides for better outcomes. Sparmann et al. compared the positioning of TKA with and without navigation support and report a very significant difference between the two groups in favor of CAOS navigation21. CAOS also seems to be quite useful in revision TKR surgeries, for which significant bone defects are often encountered and bone grafting is required.

There have been prospective randomized studies comparing the outcomes of using a navigation system during TKA with the traditional hand‐guided technique. One study found no difference in functional and clinical scores or implant survival between TKA performed with and without the assistance of a navigation system shortly after the surgery22. However, other studies have shown that the use of a navigation system does, indeed, improve the alignment of the implant, leading to significantly better outcomes. Despite the promising results, complications do arise in approximately 5%–8% of cases due to loosening, instability, dislocation, infection, or fracture23. The consensus between studies was that navigated knee arthroplasties achieve greater accuracy in implant alignment and that this difference also correlates with better knee function and improved quality of life. Although computer assistance is important for the success of TKA, the joint replacement also depends on many factors, such as patient selection, prosthetic design, soft‐tissue balancing, and proper alignment of the leg and the implant.

Shoulder Arthroplasty

Like knee and hip arthroplasty, shoulder arthroplasty can also be performed successfully, but it is highly dependent on technique. An incorrect component alignment can lead to instability, loosening, and suboptimal function24. Clinical experience with navigation shows that the procedure is safe and can provide significant surgical measurements by providing real‐time feedback of the magnitude of the deformities. Computer‐aided shoulder navigation appears to be useful in the majority of situations where shoulder arthroplasty is appropriate. It is especially useful in situations where normal anatomy is distorted, such as with fractures, revisions, and glenoid wear or dysplasia25.

Spine Surgery

The complexity of current spinal surgery techniques and instrumentation has led to the development of image guidance technologies. Computer‐assisted navigation has been used in virtually all types of spinal surgical procedures, as its use allows surgeons to better identify and avoid neurovascular structures26. CAS was first used in spinal surgery to allow for spinal fusion through the placement of lumbar pedicle screws. The navigation technology in pedicle screw placement avoids the incidence of incorrect placement of the screws under fluoroscopy guidance27. The accuracy of the insertion of pedicle screws with computer assistance has been studied since 1995. Schlenzka et al. analyzed the accuracy of insertion of 139 screws using post‐operative CT‐scans, with 133 (95.7%) correctly positioned screws in the pedicle28. The use of CAS in spine surgery has since expanded beyond its original purpose, now being used for minimally invasive techniques, decompression, and implant placement, among other procedures.

Malplacement of screws or implants, such as artificial discs for disc replacement, are common and potentially dangerous complications of spine surgery, affecting even the most experienced surgeons29. Misplaced screws can place organs in danger and may result in damaged nerves, failure of fixation, and the need for revision surgery30. The incidence of misplaced screws has been reported in the literature to be as high as 42% with the use of traditional surgical techniques, whereas studies have largely placed the rate of misplaced screws using CAS techniques to be less than 10%30. There is an overwhelming consensus based on clinical experience that computer‐assistance improves the accuracy of pedicle screw placement and can be used reliably for spinal surgery31, 32, 33.

Computer‐assisted spine surgery provides surgeons a 3‐D picture of their patient's anatomy, allowing for improvements in outcomes and decreases of intraoperative complications. Often, the computer‐assisted spine surgery system is complex and may have several components. The first part is a digital camera and computer, which work by using infrared signals to track instruments along the spine34. The smart instrumentation is made up of wireless devices, including a pedicle prober, an awl for scratching holes in bone, and a spine tracker to ensure correct positioning34, 35. Finally, software and monitors are also needed to produce the 3‐D images of the surgical site and to display the real‐time view34. Examples of CAS systems used in spine surgery are the Arcadis Orbic 3D and NaviVision navigation systems, which work together to transmit and display images30(Fig. 5).

Figure 5.

Real‐time pictures from the NaviVision spinal surgery navigation system monitor displaying the guidance and insertion of pedicle screws35.

Other uses of CAS include decompression of the spine, oncologic surgery, and minimally invasive techniques. Spinal decompression is a spinal therapy carried out to relieve symptoms such as chronic back pain brought about by compression of the nerves of the spinal cord. Improved visualization of the anatomy for this procedure, which can be provided by CAS, allows for better outcomes and reduced risks, resulting in proper decompression and reduced incidence of damage to surrounding neurovascular structures. Navigational and CT‐based technologies have shown promising results of reliable and accurate decompression with minimizal complication rates36.

Similarly, CAS has paved the way for minimally invasive techniques in spinal surgery, which are advantageous to traditional methods for a variety of reasons. Minimally invasive spine surgery involves less tissue injury and has been associated with shorter recovery, reduced postoperative pain, and improving overall function. CAS allows for greater visualization, thereby supporting these procedures; in particular, navigation systems, including 3‐D fluoroscopy‐assisted navigation, have proven useful in several types of procedures, such as percutaneous screw insertion and kyphoplasty37, 38. Finally, CAS has also proven useful for oncologic spine surgery. Certain complex pelvic and spinal tumor cases benefit from preoperative surgical planning tools, such as CT‐based and MRI‐based navigation systems, which provide the surgeon with a 3‐D assessment and visualization of the tumor bulk via a computer graphic39, 40.

Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) rupture is one of the most common sports injuries in young athletes, with an estimated 250,000 new ACL ruptures in the United States each year41. One of the more popular ACL rupture treatments is surgical reconstruction, which allows most patients to return to a normal lifestyle. Several studies have concluded that the worst clinical results leading to higher rates of revision are oftentimes caused by inaccurate placement of either the tibial or femoral tunnel in ACL reconstructions42. In fact, 70%–80% of the complications are the result of malpositioned tunnels43. As a result, computer‐assisted navigation systems were designed to improve accuracy and consistency of femoral and tibial tunnel positioning to efficiently restore knee function.

Popular opinion on CAS use for ACL surgery is divided. While proponents of navigation systems argue that CAS improves the positioning of the graft, leading to better clinical results by avoiding graft failure, the opposition highlights that these systems are associated with more operating time, which can lead to higher costs. Navigation is still an invasive procedure with accompanying risks44. Although there have been reported improvements in tunnel placement compared to conventional techniques, there are no reported improvements in functional outcomes. Andersson et al. found no significant differences between computer‐assisted and conventional ACL reconstruction with regard to tunnel placement and clinical results after a median follow‐up period of 2 years45. Although computer‐navigated systems may improve the accuracy and consistency of tunnel placement, based on clinical outcomes during short‐term follow‐up, they provide few advantages over conventional techniques. There is a clear need for further investigation.

Trauma Surgery

Current clinical applications of navigation techniques in trauma surgery include percutaneous iliosacral screw placement, percutaneous fixation of hip fractures, alignment and fixation of long bone, and spine fractures. All these applications share the need for an accurate placement of implant which can be achieved with fluoroscopy or CT‐based navigation46. Computer‐assisted navigation can be helpful in fracture treatment, especially with minimally invasive techniques, such as percutaneous fixation of femoral head fractures with cannulated screws, fractures of the acetabulum, the sacroiliac joint and the tibial plateau, and four‐part fractures of the humeral head.

Limitations and Future Directions

Computer‐assisted orthopaedic surgery has revolutionized the face of modern orthopaedic surgery, but its use is neither universal nor perfect. There are several disadvantages and pitfalls of CAS among the specialties and procedures described throughout. Namely, the cost of purchasing the CAS system, the time needed for its use, both in terms of preparation and intraoperative use, and the questionable accuracy of these technologies has limited CAS's acclaim30. In addition, surgeon expertise and practice with CAS is necessitated before mastery, and the above disadvantages can be exasperated in the early stages of transition. Many of the technologies employed in CAOS are still in the early stages of clinical use, and more clinical studies are merited to further evaluate their immediate and long‐term efficacy and safety.

In the near future, as the health‐care industry is facing changes, CAS will face and need to overcome many obstacles. For example, issues such as malpractice liability, credentialing, training requirements, health insurance, and licensing for telesurgeons are likely to be controversial. However, the vast array of advantages provided by CAS ensures its continued development and expansion. CAS offers surgeons better visualization and targeting of sites, allowing for improved diagnostic capabilities, which enhances the efficacy, safety, and cost‐effectiveness of existing clinical procedures. In addition, it decreases redundancy in the task of the surgeon and surgical errors3. The most outstanding disadvantage of CAS is the high expenses both in terms of capital costs as well as running expenses. In addition, it requires training of specialized personnel (which can also be costly) to properly repair and care for the equipment; furthermore, training is still being developed and not yet easily accessible47.

Some possibilities for expansion lay in improving the controls and the dexterity of the DaVinci system. Said improvement will further allow increased mobility without compromising the visual field to make microanastomosis possible. Another possibility for improvement in the future is the sophistication of long‐distance consultation or guidance, which may provide new opportunities for teaching and assessment of new surgeons through mentoring and simulation.

Focus on the high costs of CAS and ways to accommodate or reduce these costs should also be a priority for the future. Undoubtedly, the high cost is one of the main limitations of future progress and development of CAS. So far, CAS has been shown to be currently more expensive than conventional laparoscopic or open surgery. The incremental costs are due mainly to high surgical supply costs and the utilization of fluorescence imaging, dual consoles, simulation, and additional upgrades. CAS is expensive, but the increasing patient demand requires more comprehensive health‐care system study designs for the inevitable adoption of these costly new technologies48. Another topic that must be considered in the coming years to provide for the continued progress of CAS is the issue of surgical training. The need to increase resources for students and learning of these technologies is more imminent than ever. The lack of training hours constitutes a significant challenge to train the future surgeons in newer technologies such as robotics. Possible ways to provide a simulation experience comparable to real patients could be through computer simulation experiences or animal models.

One of the main complaints of surgeons regarding assistance and robotics is the limited tactile feedback. As a result, much research is currently underway to overcome this barrier. In 2006, Schostek et al. successfully incorporated a tactile sensor system in a laparoscopic grasper for surgical palpation in minimally invasive surgery. Subsequently, the tactile data was visually shown to the surgeon49. Fischer and Trapp have designed a system in which tactile data is fed as vibration onto the fingertips of the surgeon50. Although initial experiences appear promising, CAS is still complex and sensitive to failures due to pitfalls in software. Therefore, there is still much room for future advances to be made in this niche of surgical innovation.

More specifically, in terms of orthopaedic surgery, CAOS faces many issues going forward, despite its rapid clinical success. In spine surgery, navigation techniques have already proven their clinical relevance. Especially in orthopaedic trauma surgery, CAS will have clinically relevant implementations. The current options are probably too time consuming and expensive for basic trauma surgery, but as soon as orthopaedic and trauma surgery progressively evolve from a surgical skill based on 3‐D feel and experience into interventions based on computer‐guided planning and execution, these systems will become easy to learn and intuitive to use51. CAOS has already experienced much success in usage, applicability, and acceptance, and will continue to grow in each of these aspects provided that future directions continue to improve its functionality and decrease or accommodate for its associated risks and expenses.

Conclusions

In recent years computer technologies have become increasingly integrated in surgical procedures. The potential advantages of CAS include increase of accuracy of surgical interventions, less invasive operations, better planning and simulation, and reduction of radiation exposure for both patient and surgeon. However, there are disadvantages, such as the elevated cost, the prolonged operative times, and lack of tactile feedback as far as robotics is concerned.

After the introduction of CAS in neurosurgery, the clinical applications of this technique expanded into trauma and orthopaedic surgery. The first application of this new technique in orthopaedic and trauma surgery was for placement of lumbar pedicle screws. After its introduction into spine surgery, CAS had expanded into other fields of orthopaedic surgery like hip, knee replacement, ACL repair, as well as hip and shoulder arthroplasty. Despite all of the progress that has been made, there is still a vast amount of work to be done in the research and development of navigation systems for CAS, and, more specifically, for CAOS. Said work relies on a continued dialogue between engineers and health‐care providers to understand the perspectives of the other, keeping in site the paramount goal of providing the most cost‐effective and safe technologies and patient care.