Do New Technologies Help Knee Surgeons Meet Their Goals for Improvement?

By: R. Judd Robins, M.D.,
Member, AANA Communications and Technology Committee

As 2024 draws to a close this December, many of us enjoy the balance of participating in long-established traditions with looking forward to “the new” that comes from gifts received and resolutions to set for a new year. As we are now living in the “Fourth Industrial Revolution” defined by  internet communications, digital programming and artificial intelligence, many of us are gifted and gift new technologies to friends and loved ones with the hopes of improving quality of life. Some of these new technologies increase our capabilities to do and accomplish things in ways never imagined 5 or 10 years ago. For instance, a wearable device that measures vital signs, sleep patterns and activity levels gives an individual who sets a New Year’s resolution to “get in shape” much more objective data that hopefully supports improved fitness performance and better health.  However, the availability of more data is only helpful when used with a  “get in shape” resolution if applied with a determination to do better and be better.     

As Orthopaedic Surgeons practicing evidence-based medicine, we often leverage new technologies to improve our surgical techniques with the end goal of improving patient outcomes. We are active participants in our current Industrial Revolution as we utilize tools such as digital imaging reconstruction, computer-assisted surgery and artificial intelligence analysis that provide us with increased data points and tools for increased precision in surgical performance. One area that has seen rapid expansion of these technologies over the last fifteen years is in the performance and utilization of osteotomies around the knee.

As originally described, high tibial osteotomy was utilized to treat osteoarthritis primarily affecting those with genu varum¹. Utilization of high tibial osteotomy (open or closing wedge) has expanded to additional indications such as for a genu varum knee with failed ACL reconstruction to improve the biomechanical environment to optimize outcomes and reduce re-tear rates for revision surgery². Utilization of tibial osteotomy in ACL revision surgery has led to improved results, making this procedure a standardized tool for knee and sports medicine surgeons³. Efforts to improve the biomechanical environment to enhance ligament reconstruction surgery has expanded to other applications that utilize newer techniques (opening vs. closing)  and various osteotomy sites (distal femur, tibial tubercle) for treating osteochondral lesions, meniscal deficiency and patellofemoral maltracking^4-7. With recognition of posterior tibial slope greater than 12 degrees being a risk factor for failure after ACL revision reconstruction, anterior closing wedge osteotomies of the proximal tibia have been popularized in recent years in revision ACL reconstruction surgery⁸.

Osteotomies about the knee are not without complications. Traditionally, high tibial osteotomy has a higher rate of deep vein thrombosis (DVT), and a small but documented risk of intraarticular fracture, anterior compartment syndrome, peroneal nerve palsy, neurovascular injury, infection rate of 3% and re-operation rate of 15%^9-10. Over- and under-correction remains a challenging aspect of tibial osteotomy that can significantly affect patient outcomes, and opening wedge high tibial osteotomy (HTO) has a documented tendency to increase posterior tibial slope using conventional techniques, which can lead to unintended and adverse outcomes - in particular for ACL revision surgery^{4; 11-12}. 

As a result, leveraging technology to aid surgeons in improving their techniques has been explored since the early 2000’s^13-14. As of 2024, we have several technologies available to assist with performing osteotomies about the knee that are surgical forefathers hadn’t considered possible.

Computer-Assisted Surgery (CAS)

The purpose of using computer navigation or assistance is to increase the precision or intended correction the surgeon intends to execute.  Computer-assisted or computer navigation surgery falls into two categories: one approach utilizes CT and or MRI imaging to create 3D models of the patient’s anatomy in which preoperative and intraoperative planning and execution can be accomplished, and the second  approach utilizes a computer in the operating room to create a 3D model based upon intraoperative mapping of the patient’s anatomy which is then used to calculate angled correction. With computer assistance, the surgeon can receive feedback intraoperatively based upon the computer-generated model to execute a more precise correction. Van de Bempt and colleagues in their metanalysis in 2016 identified that computer navigation significantly improved coronal plane axis correction compared to conventional HTO surgery¹⁵. The most recently published metanalysis identified significantly improved precision with use of computer assistance to navigate osteotomy surgery¹⁶. However, surgery times averaged 10 minutes longer and no difference in outcomes were identified. In contrast, Bae and colleagues found improved outcomes, more surgeries that accomplished a corrected mechanical axis within the accurate range and non-statistically significant increase survival rates at mid-term follow-up when utilizing computer-assisted navigation in HTO¹⁷. Two additional studies identified less posterior tibial slope change, better accuracy in coronal plane correction and less radiation with use of computer navigation^18-19. While computer navigation has demonstrated improved precision in performing HTO, the significance of increased precision surgery on long-term patient reported outcomes remains to be studied.

Patient-Specific Instrumentation

There has been an increased interest over the last decade in utilizing computer 3D models to design specific surgical osteotomy corrections around the knee and utilize patient-specific instrumentation (PSI) and implants to then execute these surgeries. Most systems utilize leg length and CT imaging of the lower extremity and then take advantage of engineering software (computer-assisted design or CAD) to design an individualized surgical approach. Utilizing these technologies allow surgeons prior to surgery to first determine what angular corrections in the coronal and sagittal planes are necessary and then design the appropriate surgery and implants to match the desired correction. Advantages to utilizing this approach include determining if opening vs. closing wedge is more appropriate; allowing for a medial or lateral approach to perform both opening or closing wedge techniques; determining if distal femoral or proximal tibial osteotomy (or combined osteotomy) is more appropriate and direct plate design and screw trajectories to match the patient’s corrected anatomy and potentially accommodate concomitant procedures, such as revision ligament reconstruction, meniscal repair or allograft transplantation²⁰. Recognized goals to leveraging these technologies are their potential to reduce operative time, minimize fracture and neurovascular risk with more accurate cutting and drilling guides, less intraoperative radiation exposure, higher precision with performed correction, and preoperative planning that accounts for joint line obliquity, tibial slope and patient-specific anatomic variation. Both preclinical and clinical studies have demonstrated PSI has significantly improved precision between preoperative and executed operative angular correction when compared to conventional and computer navigation techniques^20-24.  When evaluating for accuracy in correction and short-term outcomes, two studies published in the last two years demonstrated no differences between free-hand conventional and patient-specific osteotomies^25-26.  However, the advantage to using PSI for knee osteotomies may be increased accuracy with less outliers outside the desired range for angular correction, less operative time, decreased fluoroscopy and radiation exposure and reduction in potential iatrogenic injury as identified in the most recent systematic review of PSI surgery for tibial osteotomy²⁷. In addition, the use of CAD software for preoperative planning and PSI for surgical execution can assist in more complex surgical and biplanar correction. Two recent publications in Arthroscopy Techniques demonstrate the value of leveraging these technologies to assist with performing tibial osteotomies concomitantly with ACL revision and meniscal allograft transplantation surgery^28-29.

As the year draws to a close, it is a good time for self-reflection and assessment. For Orthopaedic Surgeons who care for complex knee conditions, osteotomies about the knee are a powerful tool with already demonstrated efficacy but a reasonable risk profile. Let us each make resolutions on how to improve upon the care we render to our patients. Sometimes the benefits of leveraging technology may not be captured with patient-reported outcome measures in short to mid-term time frames. However, if we can do a surgery with greater precision in less time with a lower risk profile and lower potential for harm to our patients, let’s have the resolve to implement change, measure the impact of those changes and report our findings. Doing so is in line with the highest ideals of the profession of orthopaedic surgery and honors the spirit of our New Year’s resolutions to do better and be better.