Recent History of Osteotomies Around the Knee: From the Evolution of Planning to the Development of Personalised Approaches (and the Best is Yet to Come...)

Giacomo Dal Fabbro, MD, AUSTRALIA Gian Andrea Lucidi, MD, ITALY Claudio Belvedere, PhD, ITALY Stefano Zaffagnini, MD, Prof., ITALY

ISAKOS eNewsletters   Current Perspective 2025   Not yet rated

Introduction

After a period of low popularity corresponding to the spread of joint replacement procedures, osteotomies around the knee have been receiving increasing attention over the last two decades. Advances in 3D digital planning and additive metal manufacturing technology have made personalised approaches feasible, leading to the rapid development of patient-tailored knee osteotomies. The purpose of the present communication is to summarise key aspects of the modern history of knee osteotomies that have led to the development of the planning process and the introduction of patient-specific devices. Furthermore, the authors’ experiences and the aims of future research into personalised approaches for knee osteotomies are presented.

The Advances in Surgical Techniques and Securing Devices

In the early 1940s, based on the experience of osteotomy pioneers of the 19th century such as Rhea Barton and MacEwen, deformity-correction procedures were applied to the treatment of osteoarthritis, with early reports of promising clinical results. The work of Mark Coventry in 1965 highlighted the indications and surgical principles that are still relevant today, such as the degenerative disease of only one compartment of the knee and the need for full correction of the deformity . He developed and described a closing-wedge technique involving the use of one or two stepped staples, which improved the congruence and the contact surface of the bone with the device. In later years, stepped staples were used for fixation during closing-wedge tibial osteotomy (Figure 1). Later, the application of the AO foundation fixation devices provided good results and the potential to achieve early stable fixation with the use of the AO T-plates for the tibia and the 90° AO distal blade plate for the femur. In the 1990s, dynamic external fixation was utilised for proximal tibial osteotomies, offering the advantages of early weight-bearing and the potential postoperative control of the correction, but high surgical technical demand and patient compliance were significant limitations of this method. Puddu, whose work was responsible for a revival of the opening-wedge technique osteotomy in the late 1990s and early 2000s, developed a widely used stainless plating system that featured a spacer to fill the gap and help maintain the correction (Figure 2). In the same years, Lobenhoffer and the German school described the cornerstones of the current surgical techniques: the use of stable angular devices such as the TomoFix plate (Figure 2) to secure the osteotomy, and the consideration of the location of the malalignment in the planning of the correction.

Fig. 1 Stepped staple for lateral closing-wedge osteotomy securing

Fig. 2 The 5-hole Puddu plate for opening-wedge osteotomy securing (left) and the Tomofix stable angular plate for proximal tibial osteotomy securing (right)

The Development of Planning: From the First Correction Targets to the Three-Dimensional Analysis of Deformities

The recent publication of the consensus of the European Society of Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA) on varus knee osteotomy affirms the crucial role of surgical planification and deformity definition in expanding the indications for successful knee osteotomy. The development of the current concept of deformity analysis and correction and planification has been a long and complex process. In the first half of the 20th century, thanks to the development and spread of radiographic analysis, surgeons involved in the analysis and correction of limb deformities began to discuss alignment goals, gradually evolving from the concept of an anatomical axis to a mechanical axis, evaluating malalignments on full-leg-length images.

However, a clear definition of the goal of correction was lacking until 1979, when Fujisawa and colleagues demonstrated that shifting the weight-bearing line to a lateral point 30%-40% relative to the midpoint of the tibial plateau resulted in histological regeneration of fibrocartilage in varus patients with medial osteoarthritis who were treated with a valgus-producing HTO. In the following years, further preoperative planning techniques were introduced in the surgical practice, such as those proposed by Miniaci and Dugdale, which take into account not only mechanical alignment but also ligamentous laxity assessed by stress testing in varus and valgus. In 1989, concluding a decade full of significant innovations, Dror Paley described the principles of deformity correction and highlighted the cardinal role of the center of rotation of deformity, laying the foundation for contemporary methods of deformity assessment and correction planning. In the late 1990s and early 2000s, Chambat and the Lyon School highlighted and made significant contributions to the understanding of the relationship between changes in the coronal and axial planes at different degrees of flexion after knee osteotomies. The importance of considering the center of rotation of the deformity in the setting of knee osteotomy was highlighted in the early 2000s by Babis, who linked it to the concept of maintaining neutral joint line obliquity in addition to addressing limb malalignment around the knee by considering a two-level correction. Since then, double-level osteotomy and the need to preserve joint line obliquity have influenced the evolution of surgical planning and today continue to be significant topics of debate in the field of osteotomy. At the beginning of the second decade of the 21st century, the development of planning was suddenly accelerated by the application of new technologies and a renewed interest in joint preservation surgery. The classic correction target described by Fujisawa was updated with a more individualized approach based on the degree of osteoarthritis of the affected compartment, as described by the Munich school in an approach-proposal paper by Feucht et al. To achieve real-time intraoperative assessment of alignment and correction, computer navigation has been applied to osteotomies around the knee, with results showing improved accuracy and reproducibility of correction, as reported by Neri et al. However, increased surgical cost and time and the need to use pins, along with the lack of clear evidence of clinical benefit, have been barriers to the widespread adoption of the use of computer navigation in this setting.

With regard to the selection of the most suitable patient for knee osteotomy, efforts have been made to understand the demographic and preoperative factors associated with higher or lower rates of clinical success, as reported by Batailler and Mabrouk in studies published in 2023 and 2024. This type of research has become the cornerstone of the development of predictive analytics for patients who are candidates for knee osteotomy and will makea significant contribution in the massive application of machine learning processes in this field. Regarding the execution of planning, Elson observed the high reliability of digital planning using Miniaci's method, and Charre and colleagues recently confirmed the significantly higher accuracy provided by digital planning compared with previous non-digital methods, expressed as the “dogma of one millimeter equals one degree.” Despite these good results, the quest for further improvement in planning has continued to advance, and, with the availability of advanced imaging technologies and the development of specific software, 3D planning systems have been introduced in the context of knee osteotomy. In addition, along with 3D analysis, surgeons recently have paid increasing attention to multiplanar features of the deformity, with the primary goal of avoiding complications and addressing knee instability by performing tibial slope modification osteotomies.

The Input of Patient-Specific Devices for Osteotomies Around the Knee

Although the importance of achieving the specific desired correction goal for each patient undergoing knee osteotomy has been confirmed, a significant recurrence of correction inaccuracy has been reported in association with both standard and computer navigation-assisted surgical techniques. In addition, the persistence of a risk of complications, including neurovascular injury, in the setting of knee osteotomy has been described, leading to the perception that these procedures are technically challenging. Moreover, clear evidence of the detrimental effect of posterior tibial slope in cases of knee instability or cruciate ligament reconstruction has highlighted the need to consider multiplanar deformities.

Patient-specific devices, which were tested and introduced to address these issues early in the second decade of the 2000s, have made the direct link between three-dimensional digital planning and the surgical procedure a practical reality. Most of the available literature on patient-specific devices for knee osteotomy has evaluated customized cutting guides to achieve accurate osteotomy position and avoid surgical complications during bone cutting. The good results provided by cadaver studies were confirmed by the first in vivo pilot study using 3D planning and custom cutting guides, published in 2013 by Victor and colleagues, who reported excellent correction accuracy in both the coronal and sagittal planes.

The results were later confirmed by Chaouche and the Marseille group in the larger prospective cohort of patients undergoing valgus-producing high tibial osteotomy with a patient-specific cutting guide, which demonstrated average differences of 1° and 0.4° between the target and achieved coronal mechanical alignment and posterior tibial slope, respectively. Because of the increase in accuracy and the reduction of outliers, along with the need for more complex corrections in different planes, the interest and application of patient-customized devices in the setting of knee osteotomy are continuously increasing, and several types of custom systems that rely on 3D digital planning and 3D printing technologies have been described and tested before being introduced into surgical practice. The higher cost of the patient-specific instrumentation as compared with standard devices should be considered in the assessment of the cost-effectiveness of a personalised approach. However, the Marseille group, in a study by Jacquet et al., found that patient-specific devices resulted in decreasing operating time and the number of fluoroscopic images taken during surgery. Therefore, while the cost of patient-specific devices represents a limitation of the personalised approach, such devices are worth considering in the setting of high tibial osteotomy due to the promising clinical results and surgical advantages reported in the literature.

Personalised Protocol for Knee Osteotomy with 3D-Printed Devices and the Biomechanical Evaluation of Knee Function: The Rizzoli Experience

A clinical study aimed at developing and testing a fully customized system for high tibial osteotomy was conducted at the authors’ institution. The system being tested (TOKA [Tailored Osteotomy Knee Alignment system], Orthoscape, UK) is based on a standard preoperative long-leg radiograph and a 3D scan of the knee with cone-beam computed tomography (CT), both performed under loaded conditions. The position and angle of the osteotomy line and hinge, along with any desired changes in the posterior tibial slope, are selectable using the 3D cone beam CT data. The surgeon is also able to select screw positions and plan around any existing hardware related to previous knee procedures. TOKA planning software, using CT data, evaluates the depth of the anterior and posterior osteotomy cut. The planning software then generates the geometries of the surgical guide, high tibial osteotomy stabilization plate, and screws (Figure 3). The surgical guide and plate are produced by 3D printing from medical-grade titanium alloy powder (Ti6AL4V).

Positioning of the cutting template, which is the most crucial aspect of the procedure, was improved during the case series with the addition of a posterior grasping function to align with the patient’s posterior tibial cortex and with the provision of synthetic fluoroscopic images of the surgical guide positioning. In addition, the surgical guide also incorporates an integrated screw-opening system, which eliminates the need for multiple instruments and allows the desired correction to be precisely achieved.

The study protocol also included preoperative and postoperative gait analysis and electromyography associated with the collection of objective clinical data and patient-reported outcomes. The infrared fiducial markers that were used during gait analysis also were used during cone beam CT in order to enable researchers to perform morphological reconstruction and data recording. Gait analysis and complete image evaluation, including cone beam CT, were performed at 6 months after high tibial osteotomy.

The first clinical analysis at 1 year of follow-up demonstrated the safety of the customized system that was analysed, which provided good accuracy in correcting coronal and sagittal alignment. In addition, excellent clinical results were found, particularly in terms of the resolution of pain and the restoration of function.

The availability of data obtained from gait analysis and cone beam CT allowed the researchers to perform preoperative and follow-up biomechanical analyses. With use of the same reflective markers around the knee during gait analysis and cone beam CT, functional data collected through gait analysis during flat walking were recorded on images acquired with CT, and the corresponding DICOM files were used to reconstruct 3D models for the additional bones and markers; this combination was used to record the positions of ground reaction force vectors on the tibial bone model during various gait tasks. The results of these analyses showed a clear lateralization of ground reaction force after high tibial osteotomy and highlighted the potential role of this 3D bone modelling combined with motion analysis to improve high tibial osteotomy planning. In addition, the accuracy of the correction deformity was evaluated using distance map analysis obtained with 3D cone beam CT. Geometric differences between the 3D morphology of the proximal tibia in preoperative planning and the actual proximal tibia assessed at follow-up were performed with distance map analysis, showing accurate planned correction and plate placement.

The functional and biomechanical analysis performed in the presented study, in association with 3D planning and printing technologies, provided a huge interaction of information and potential tools that can lead to the completion of a personalized and functional approach for knee osteotomy. The same system has also been applied for distal femoral osteotomy with varus production in patients with valgus malalignment and lateral osteoarthritis, with promising results (Figure 4). The next major challenge is to incorporate the various information to define a safe and effective treatment pathway tailored to the needs and functional characteristics of the specific patient. Data-driven decision-making made possible by artificial intelligence (AI) technologies and, in particular, its subset called machine learning, seems to be a powerful and promising tool to achieve this. Despite the many limitations that still need to be addressed, such as the lack of rigorous validation of machine learning models on different study populations and the absence of standardized evaluation metrics, the future direction of research for an increasingly personalized treatment approach seems to be the application of these analysis and decision algorithm systems to the field of joint preservation interventions and knee osteotomies. Because the possibility of using one of the most powerful tools available to improve treatment efficacy and patient outcomes is at stake, further research efforts and studies aimed at applying AI to the personalization of knee osteotomy are strongly needed.

Fig. 3 TOKA customised cutting guide with the screw opening mechanism for medial opening-wedge high tibial osteotomy (left) and TOKA customised plate and screws for medial opening-wedge high tibial osteotomy securing (right)

Fig. 4 TOKA medial distal femoral closing-wedge customised cutting guide (left) and TOKA customised plate and screws for medial distal femoral closing-wedge osteotomy (right)

Conclusion and Take-Home Message

The need for an effective approach in the management of active patients with degenerative joint disease and malalignment has been responsible for reconsidering the role of osteotomies around the knee in the last twenty years. Recently, surgical techniques and technologies have been applied in the setting of knee osteotomies with the aim to improve the correction’s accuracy and the patients’ outcomes. Furthermore, predictive factors for success or failure of knee osteotomies have been investigated, including clinical and biomechanical data. The next challenge will be to apply the machine learning technology to provide surgeons with predictive algorithm of the outcomes and information about the best approach in terms of technique and amount of correction.

References

1. Roussot MA, Huijs S, Oussedik S. From Hippocrates to Coventry and Beyond: The History of Joint Realignment. In: Oussedik S, Lustig S, eds. Osteotomy About the Knee. Springer;2020.
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