Study to Evaluate the Performance of Navigated TKA With OrthoPilot® pheno4u TKA Level 1

The primary variable delta (aHKA), is defined as the difference in the arithmetic hip-knee-angle (aHKA) between the 3 months postoperative and the intraoperatively planned value. The aHKA is calculated as the difference of the mechanical medial proximal tibial angle (MPTA) and the mechanical lateral distal femoral angle (LDFA), both measured in degrees.

Secondary interventions at the index knee

The Oxford Knee Score (OKS) is a validated joint-specific patient-reported outcome measure that is commonly employed to assess the outcome of TKA. It is a 12-item, patient-reported questionnaire originally developed and validated specifically to assess function and pain in patients undergoing TKA. It is short, reproducible, valid and sensitive to clinically important changes over time. OKS ranges from 0 to 48 with 48 being the best outcome.

The FJS-12 contains 12 questions. Every question is scored 1 (never) to 5 (mostly) according to the selected response categories. Thus, the raw score ranges from 12 to 60. The raw score is linearly transformed to a 0-100 scale and then reversed to obtain the final score.

Final score = 100 - ((sum(item01 to item12) - 12)/48*100). Lower scores indicate less awareness of the operated knee during daily activities. The range of the final score is from 0 to 100 (where 0 is worst and 100 means best score)

Quality of life of the patients will be analyzed using the 5-dimensions 5-level measure of the EuroQol Group (EQ-5D-5L), which is a simple and generic measure for clinical and economic assessment.

The questionnaire covers five different dimensions (mobility, self-care, usual activities,pain/discomfort, anxiety/depression) rated in 5 levels (from "the worst health you can imagine" to "the best health you can imagine"). The questionnaire is filled by the patients themselves.

The Net Promoter Score (NPS) was developed for measuring satisfaction in economic research.

Colloquially, it is referred to as the "friends and family test". In the healthcare sector, the NPS is used as an overarching measure of patient satisfaction. The NPS metric evaluates the likelihood that a patient will recommend the received healthcare service to others. The NPS is assessed using a scale from 1 to 10. A rating between 9 and 10 is classified as a promoter. A rating between 7 and 8 is considered neutral, and a rating between 0 and 6 is deemed a detractor. The overall score is simply calculated by subtracting the percentage of detractors from the percentage of promoters.

Scores range from -100 (everyone is a detractor) to +100 (everyone is a promoter). In the industry, a positive score is viewed favorably, and scores above 50 are considered indicative of strong performance.

Anterior knee pain will be used to evaluate the performance of the implantation and the implant itself.

Rating Description Points:

0 = No pain (0 Points) I = Mild pain that does not intrude on daily activities (5 Points) II= Moderate pain that is a nuisance; patient not considering further surgery (10 Points) III= Severe pain; patient considering further surgery (15 Points)

Routinely performed radiographic images are used to evaluate the status of the affected knee, preoperatively, and the status of the implant components, postoperatively. Analysis of parameters will be defined in the radiographic protocol, where precise definition of the implant alignment parameter of the tibial and femoral component by measurement of the LDFA (laterale distale Femurankle) and MPTA (medial proximal Tibiaankle) is given. Both ankles have the same unit and are measured in degrees.

During the course of the study, any upcoming intra- or postoperative (serious) adverse will be documented. The total number of AEs will be summarized and further evaluated by the sponsor and reported according to local legislation and necessity. Recorded complications will be categorized and analyzed to assess the safety of the investigational product.