In vivo comparison of femorotibial contact positions for Press-Fit posterior stabilized and posterior cruciate–retaining total knee arthroplasties

• Published in: The Journal of arthroplasty Vol. 17; no. 2; pp. 209 - 216
• Main Authors: Komistek, Richard D., Scott, Richard D., Dennis, Douglas A., Yasgur, David, Anderson, Dylan T., Hajner, Mary E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2002
• Subjects: Arthroplasty, Replacement, Knee; Computer Simulation; Femur - anatomy & histology; fluoroscopy; Humans; in vivo; Knee Joint - diagnostic imaging; Posterior Cruciate Ligament - physiology; Posture; Prosthesis Fitting; Radiography; Tibia - anatomy & histology; total knee arthroplasty; fluoroscopy; total knee arthroplasty; in vivo
• ISSN: 0883-5403; 1532-8406
• DOI: 10.1054/arth.2002.29329

The objective of this study was to determine the in vivo medial and lateral femorotibial condyle contact positions for 20 subjects having either a posterior cruciate–retaining (PCR) or posterior-stabilized (PS) total knee arthroplasty (TKA) while sitting and kneeling. The two-dimensional radiographic images were converted into three-dimensional images using an iterative computer model-fitting technique. Anteroposterior contact positions, axial rotation, and condylar lift-off were assessed for each subject. In a seated position, the femorotibial contact points were, on average, posterior for both TKA groups (PCR: medial = −2.4 mm, lateral = −3.4 mm; PS: medial = −5.1 mm, lateral = −8.9 mm; medial, P=.21; lateral, P=.08). In a kneeling position, the contact position shifted anteriorly for the PCR TKA group (medial = 0.9 mm, lateral = −0.8 mm), whereas the contact positions in the PS TKA group remained posterior (medial = −5.6 mm, lateral = −8.3 mm; medial, P=.002; lateral, P=.0004). It is hypothesized that while in a kneeling position, the posterior cruciate ligament has less resistance to the anterior thrust of the femur relative to the tibia than in a PS TKA, in which this force is absorbed in the cam-and-post mechanism.