Guided Personalized Surgery (GPS) in Posterostabilized Total Knee Replacement: A Radiological Study

Background: Surgical accuracy in total knee replacement (TKR) may vary with the surgeon, the patient preoperative deformity, and the guiding system to perform the procedure. Navigation systems attempt to increase the intraoperative information the surgeon requires to make the appropriate decisions, sometimes associating cumbersome procedures and unclear effectiveness to place the implant more precisely than conventional instruments. Methods: We conducted a retrospective case-control study with prospective data collection of radiographic measurements (alignment, joint line and patellar height) in a sample of 100 consecutive patients receiving TKR Optetrak Logic PS, either with standard surgical technique with Trulion Instrumentation (n = 59) or with the Guided Personalized Surgery (GPS) system (n = 41). Results: The GPS group improved the alignment of the mechanical Lateral Distal Femoral Angle (mLDFA) in 1.6° compared to the control (p = 0.003), but not evident in the mechanical Medial Proximal Tibial Angle (mMPTA) (p = 0.132). The GPS system achieved a normal patellar height in 98% of cases, according to the Blackburne-Peel Index (BP), compared to 71% in the control group (p = 0.002). This was obtained in the femoral side, as measured in the Epicondylar Ratio (ER) (p = 0.004). A lower dispersion of postoperative measurements was observed in the GPS group in comparison with the control, being statistically significant in mMPTA (p = 0.000), CD-Index (p = 0.011), IS-Index (p = 0.002), mIS-Index (p = 0.008), BP-Index (p = 0.011), and ER (p = 0.004). Conclusions: Better post-surgical restoration of joint line and patellar height is observed in surgeries performed with the GPS system, as well as a tendency to more accurate mechanical alignment and lower inter-patient variability, suggesting higher reproducibility.