Femoral rollback of cruciate-retaining and posterior-stabilized total knee replacements: in vivo fluoroscopic analysis during activities of daily living.
Restoration of the physiological flexor/extensor mechanism at the knee in terms of appropriate muscular lever arms, proper required quadriceps force, and suitable patellofemoral compressive force, is fundamental for the success of total knee replacement. Therefore, measurements of anteroposterior translation of the femoral component over the tibial base-plate against joint flexion during daily living activities are essential for the assessment of the in vivo performance of current prosthesis designs. Patients treated with posterior stabilized and cruciate retaining prostheses with excellent clinical scores were evaluated during stair climbing, sitting and rising from a chair, and step up and down, using a three-dimensional pose reconstruction technique based on videofluoroscopy. The posterior stabilized patients experienced a fairly consistent and physiological rollback specific of each motor task, demonstrating proper function of the spine-cam mechanism. Rollback was somehow inconsistent among subjects in the cruciate retaining group, accompanied with a smaller range of knee flexion. In this group, more posterior locations of the condyles correlated significantly with higher clinical and functional scores. Articular surface conformity restores physiological rollback in the presence of a spine-cam mechanism, but not coherently in the presence of the posterior cruciate ligament.
Fantozzi
Silvia
S
Department of Electronics, Computer Science and Systems, Università di Bologna, Viale Risorgimento 2, 40136 Bologna, Italy. fantozzi@ior.it
Catani
Fabio
F
Ensini
Andrea
A
Leardini
Alberto
A
Giannini
Sandro
S
D000203:Activities of Daily Living; D016118:Anterior Cruciate Ligament / Q000502:physiology*; D019645:Arthroplasty, Replacement, Knee; D001696:Biomechanical Phenomena / Q000379:methods*; D005269:Femur / Q000502:physiology*; D005471:Fluoroscopy; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D007720:Knee Prosthesis; D009068:Movement; D016119:Posterior Cruciate Ligament / Q000502:physiology*; D011474:Prosthesis Design; D012399:Rotation