Computer Assisted Surgery Evaluation of Femoral Component Rotation in Well-Balanced and Well-Aligned Total Knee Arthroplasty Using Gap Technique
Pruk Chaiyakit MD*, Surapoj Meknavin MD*
Affiliation : * Department of Orthopedic Surgery, Vajira Hospital School of Medicine, Navamindradhiraj University, Bangkok, Thailand
Objective : Using computer assisted surgery (CAS) to assess femoral component rotation in well-balanced, well-aligned total
knee arthroplasty (TKA) implanted with Posterior Cruciate Ligament (PCL) excision type prosthesis using gap technique.
Material and Method: Using CAS, well-balanced TKA was defined by both flexion/extension and medial/lateral gap difference
of less than 2 mm and well-aligned TKA was defined by final mechanical axis within + 3 degrees deviation and flexion
contracture of less than 5 degrees without hyper extension. Femoral component rotation was determined by posterior
condylar axis versus proximal tibia resection plane. The present study analyzed data from January 1, 2009 to September 30,
2009.
Results : Out of 65 knees, 34 knees (14 fixed and 20 mobile bearing prosthesis) were considered well-balanced and well-
aligned. Mean femoral component rotation was 2.12 + 3.38 degrees. Seven knees were within 2-4 degrees external rotation.
There was no statistically significant difference of femoral component rotation between fixed and mobile bearing.
Conclusion : Wide range of femoral component rotation occurred in well-aligned and well-balanced TKA using PCL excision
type prosthesis.
Keywords : Computer assisted surgery, CAS, Femoral rotation, Well-balanced TKA
