**5. New technologies**

#### **5.1 Computer-assisted navigation in valgus knee**

Computer-assisted navigation (CAN) was developed to improve the position of the implants, achieving more accurate postoperative alignment through more precise and reproducible bony resection and ligament balancing [28].

Regarding the use of CAN in valgus TKAs, there are some published case series. Hadjicostas et al. [29] described the results of 15 knees with a mean valgus deformity of 21° (17–27°) and a mean follow-up of 28 months (24–60). All the knees were corrected to a mean of 0.5° of valgus (0–2 degrees).

Shao et al. [30] presented the results of six cases of CAN-assisted valgus TKA, in which ideal mechanical and prosthetic alignment was achieved with an image-free, computer-assisted navigation system. A primary, posterior-stabilized prosthesis was utilized in all cases. The average preoperative overall mechanical axis of the seven knees was 19.6° ± 4.6° of valgus, and the average postoperative mechanical axis was 0.4° ± 0.7°.

Between 2002 and 2009, Huang et al. [31] reported in a retrospective study, the results of 62 patients (70 knees) with Ranawat type-II valgus deformity who underwent primary TKA with or without CAN. At a mean follow-up of 6.2 years, both groups had significant postoperative improvements in clinical performance.

Unfortunately, there are still no good-quality randomized clinical trials that demonstrate evidence for the routine use of CAN in valgus TKAs. The decision remains based on the surgeon's common sense and experience.

#### **5.2 Robotics and 3D printed implants in valgus knee**

In recent years, the launch of new robotic platforms has caused great interest on the part of orthopedic surgeons. The use of robotic surgery in TKA improves the accuracy of knee alignment, implant positioning, and ligament balance, although

it does not demonstrate superiority in clinical-functional outcome [32]. However, surgeons new to the robotics technique have been advised by more experienced ones to avoid valgus deformities at the beginning of the learning curve. The opinion of experts is that this is a challenge that requires more experience with the technique.

Marchant et al. [33] analyzed a series of cases with complex deformities undergoing knee arthroplasties and noted that robotic devices can help correct severe deformities, both in valgus with varus and in cases of flexion contracture. New studies should be carried out to analyze the clinical superiority of the use of robots in cases of valgus deformity. It was observed in another study that in seven knees with valgus deformity, all were corrected for alignment in neutral and without overcorrection [34].

Another recent technology is the manufacture of personalized implants. The use of 3D modeling techniques based on computed tomography in challenging cases of valgus deformity allows components to be placed in positioning according to the patient's anatomy in the coronal, sagittal, and transverse planes. This type of technology allows surgeons to make intraoperative adjustments and can place components outside of preoperative planning guidelines based on each patient's clinical need [35].
