Trochlear sulcus modeling for femoral implant positioning during navigated TKA

Background: Patellofemoral complications and mid-flexion instability remain significant causes of patient dissatisfaction following total knee arthroplasty (TKA). While femoral component malpositioning and overstuffing are known contributors to anterior knee pain, the sagittal geometry of the trochlear groove in osteoarthritic patients has not been extensively characterized using intraoperative data.

Objective: This study aimed to quantify the sagittal curvature of the trochlear sulcus in patients undergoing TKA and to evaluate the clinical utility of using this geometry as an intraoperative landmark for femoral component positioning.

Key Points: Intraoperative navigation was used to map the trochlear sulcus in 110 consecutive patients. The sagittal geometry was accurately modeled as a circular arc with a mean radius of 25.5 ± 5.6 mm. The sulcus exhibited a mean external rotation of 3.2° ± 4.3° relative to the posterior condylar axis and 3.9° ± 5.3° relative to the mechanical axis. No significant correlations were found between the trochlear radius and gender or femoral length. In a clinical cohort of 60 cases where this modeling guided implant positioning, significant improvements were observed in Knee Society Scores and patellar pain scores at 12-month follow-up, with 60% of patients reporting no pain by the first postoperative month.

Conclusion: The native trochlear groove in osteoarthritic knees maintains a consistent circular sagittal profile that is independent of gender or femoral dimensions. Utilizing this geometry as an intraoperative reference allows for precise femoral component alignment, potentially reducing patellofemoral complications and improving early clinical outcomes.