Umberto Cardinale1, Laura Bragonzoni2, Marco Bontempi3, Domenico Alesi4, Tommaso Roberti di Sarsina4, Mirco Lo Presti5, Stefano Zaffagnini6, Giulio Maria Marcheggiani Muccioli7, Francesco Iacono8. 1. University of Bologna, Italy. 2. University of Bologna, Italy. Electronic address: laura.bragonzoni4@unibo.it. 3. University of Bologna, Italy. Electronic address: m.bontempi@biomec.it. 4. II Orthopaedic and Traumatologic Clinic - IRCCS - Istituto Ortopedico Rizzoli, Bologna, Italy. 5. II Orthopaedic and Traumatologic Clinic - IRCCS - Istituto Ortopedico Rizzoli, Bologna, Italy. Electronic address: m.lopresti@biomec.ior.it. 6. II Orthopaedic and Traumatologic Clinic - IRCCS - Istituto Ortopedico Rizzoli, Bologna, Italy. Electronic address: stefano.zaffagnini@unibo.it. 7. II Orthopaedic and Traumatologic Clinic - IRCCS - Istituto Ortopedico Rizzoli, Bologna, Italy; University of Bologna, Italy. Electronic address: marcheggianimuccioli@me.com. 8. Department of Biomedical Sciences, Humanitas University, Via Manzoni 113, Rozzano, Milan 20089, Italy; Humanitas Clinical and Research Center, Via Manzoni 56, Rozzano, Milan 20089, Italy.
Abstract
PURPOSE: This work presents a kinematic evaluation of a cruciate retaining highly congruent mobile bearing total knee arthroplasty design using dynamic Roentgen sterephotogrammetric analysis. The aim was to understand the effect of this implant design on the kinematics of prosthetic knees during dynamic activities. METHODS: A cohort of 15 patients was evaluated at nine month follow-up after surgery. The mean age was 74.8 (range 66-85) years. The kinematics was evaluated using the Grood and Suntay decomposition and the Low-Point (LP) methods. RESULTS: ?tlsb=-0.15pt?>From sitting to standing up position, the femoral component internally rotated (from -11.3 ± 0.2° to -7.0 ± 0.2°). Varus-valgus rotations were very close to 0° during the whole motor task. LP of medial condyle moved from an anterior position of 12.0 ± 0.2 mm to a posterior position of -12.4 ± 0.2 mm; LP of the lateral condyle moved from an anterior position of 8.1 ± 0.2 mm to a posterior position of -12.4 ± 0.2 mm, showing a bi-condylar rollback where both condyles moved parallel backward. Moreover, the femoral component showed anterior translation with respect to the tibia from 80° to 20° (from -4.9 ± 0.2 mm to 3.3 ± 0.2 mm), then a posterior translation from 20° to full extension was identified (from 3.3 ± 0.2 mm to 0.5 ± 0.2 mm). CONCLUSIONS: Paradoxical anterior femoral translation and absence of medial-pivoting motion were recorded, highlighting the role of the symmetric deep dishes insert as main driver of the kinematic of this TKA design.
PURPOSE: This work presents a kinematic evaluation of a cruciate retaining highly congruent mobile bearing total knee arthroplasty design using dynamic Roentgen sterephotogrammetric analysis. The aim was to understand the effect of this implant design on the kinematics of prosthetic knees during dynamic activities. METHODS: A cohort of 15 patients was evaluated at nine month follow-up after surgery. The mean age was 74.8 (range 66-85) years. The kinematics was evaluated using the Grood and Suntay decomposition and the Low-Point (LP) methods. RESULTS: ?tlsb=-0.15pt?>From sitting to standing up position, the femoral component internally rotated (from -11.3 ± 0.2° to -7.0 ± 0.2°). Varus-valgus rotations were very close to 0° during the whole motor task. LP of medial condyle moved from an anterior position of 12.0 ± 0.2 mm to a posterior position of -12.4 ± 0.2 mm; LP of the lateral condyle moved from an anterior position of 8.1 ± 0.2 mm to a posterior position of -12.4 ± 0.2 mm, showing a bi-condylar rollback where both condyles moved parallel backward. Moreover, the femoral component showed anterior translation with respect to the tibia from 80° to 20° (from -4.9 ± 0.2 mm to 3.3 ± 0.2 mm), then a posterior translation from 20° to full extension was identified (from 3.3 ± 0.2 mm to 0.5 ± 0.2 mm). CONCLUSIONS: Paradoxical anterior femoral translation and absence of medial-pivoting motion were recorded, highlighting the role of the symmetric deep dishes insert as main driver of the kinematic of this TKA design.