PURPOSE: Poor knee extension function after total knee arthroplasty (TKA) is associated with factors including articular geometry and alignment. Femoral trochlear geometry has evolved from symmetrical to become more prominent proximal-laterally, with the groove aligned proximal-lateral to distal-medial. This study in vitro tested the hypothesis that a modern asymmetrical prosthesis would restore patellar tracking and stability to more natural behaviour than an older symmetrical prosthesis. METHODS: Six knees had their patellar tracking measured optically during active knee extension. Medial-lateral force versus displacement stability was measured at fixed angles of knee flexion. The measurements were repeated after inserting each of the symmetrical and asymmetrical TKAs. RESULTS: Significant differences of patellar lateral displacement stability, compared to normal, were not found at any angle of knee flexion. The patella tracked medial-laterally within 2.5 mm of the natural path with both TKAs. However, for both TKAs near knee extension, the patella was tilted laterally by approximately 6° and was also flexed approximately 8° more than in the natural knee. CONCLUSION: The hypothesis was not supported: The more anatomical component design did not provide more anatomical patellar kinematics and stability.
PURPOSE: Poor knee extension function after total knee arthroplasty (TKA) is associated with factors including articular geometry and alignment. Femoral trochlear geometry has evolved from symmetrical to become more prominent proximal-laterally, with the groove aligned proximal-lateral to distal-medial. This study in vitro tested the hypothesis that a modern asymmetrical prosthesis would restore patellar tracking and stability to more natural behaviour than an older symmetrical prosthesis. METHODS: Six knees had their patellar tracking measured optically during active knee extension. Medial-lateral force versus displacement stability was measured at fixed angles of knee flexion. The measurements were repeated after inserting each of the symmetrical and asymmetrical TKAs. RESULTS: Significant differences of patellar lateral displacement stability, compared to normal, were not found at any angle of knee flexion. The patella tracked medial-laterally within 2.5 mm of the natural path with both TKAs. However, for both TKAs near knee extension, the patella was tilted laterally by approximately 6° and was also flexed approximately 8° more than in the natural knee. CONCLUSION: The hypothesis was not supported: The more anatomical component design did not provide more anatomical patellar kinematics and stability.
Authors: D T T Lie; N Gloria; A A Amis; B P H Lee; S J Yeo; S M Chou Journal: Knee Surg Sports Traumatol Arthrosc Date: 2004-05-04 Impact factor: 4.342
Authors: Carolyn Anglin; Jill M Brimacombe; David R Wilson; Bassam A Masri; Nelson V Greidanus; Jérôme Tonetti; Antony J Hodgson Journal: J Arthroplasty Date: 2009-07-29 Impact factor: 4.757
Authors: Farhad Iranpour; Azhar M Merican; Ferdinando Rodriguez Y Baena; Justin P Cobb; Andrew A Amis Journal: J Orthop Res Date: 2010-05 Impact factor: 3.494
Authors: Daniel N Bracey; Matthew L Brown; Hoyt R Beard; Sandeep Mannava; Omar F Nazir; Thorsten M Seyler; Jason E Lang Journal: Int Orthop Date: 2015-03-18 Impact factor: 3.075
Authors: In Jun Koh; Il Jung Park; Charles C Lin; Nilay A Patel; Christen E Chalmers; Mauro Maniglio; Michelle H McGarry; Thay Q Lee Journal: Knee Surg Sports Traumatol Arthrosc Date: 2018-10-28 Impact factor: 4.342