"The realignment of PF joint is also a major concern in total knee arthroplasty. The rate of PF complications after knee arthroplasty ranged from 4% to 41% . To improve the success rate, the design of prosthesis is still developing in terms of restoring the physiological PF kinematics . "
[Show abstract][Hide abstract] ABSTRACT: Patellofemoral (PF) maltracking is a critical factor predisposing to PF pain syndrome. Many novel techniques of measuring patellar tracking remain research tools. This study aimed to develop a method to measure the in vivo patellar tracking and finite helical axis (FHA) by using a static magnetic resonance (MR) based methodology. The geometrical models of PF joint at 0°, 45°, 60°, 90°, and 120° of knee flexion were developed from MR images. The approximate patellar tracking was derived from the discrete PF models with a spline interpolation algorithm. The patellar tracking was validated with the previous in vitro and in vivo experiments. The patellar FHA throughout knee flexion was calculated. In the present case, the FHA drew an “L-shaped” curve in the sagittal section. This methodology could advance the examination of PF kinematics in clinics, and may also provide preliminary knowledge on patellar FHA study.
"Factors associated with atraumatic patellar fractures include patellar subluxation, improper patellar resection, vascular compromise, component designs and thermal necrosis [13,15]. Even restoration of postoperative flexion in a previous stiff knee has been proposed as a potential cause of fracture [13,15]. "
[Show abstract][Hide abstract] ABSTRACT: Conversion of a knee arthrodesis to a Total Knee Arthroplasty is an uncommon procedure. Revision Total Knee Arthroplasty in this setting presents the surgeon with a number of challenges including the management of the extensor mechanism and patella.
We describe a unique case of a 69 years old Caucasian man who underwent a revision Total Knee Arthroplasty using a tibial tubercle osteotomy after a previous conversion of a knee arthrodesis without patella resurfacing. Unfortunately 9 months following surgery a tibial tubercle pseudarthrosis and spontaneous patella fracture occurred. Both were managed with open reduction and internal fixation. At 30 months follow-up the tibial tubercle osteotomy had completely consolidated while the patella fracture was still evident but with no signs of further displacement. The patient was completely satisfied with the outcome and had a painless range of knee flexion between 0-95[degree sign].
We believe that patients undergoing this type of surgery require careful counseling regarding the risk of complications both during and after surgery despite strong evidence supporting improved functional outcomes.
[Show abstract][Hide abstract] ABSTRACT: In order to study the influence of some position changes of prosthesis in patello-femoral joint on knee mechanism after total knee arthroplasty, a three-dimensional model of knee joint including patello-femoral joint has been developed. Changes in position parameters of patellar or femoral prosthesis were simulated. Patellar lateral transition, ratio of patellar tendon force to quadriceps force, and ratio of patello-femoral compressive force to quadriceps force are choosing to response performances of knee extensor mechanics. Results show that patellar thickening, patellar medial rotation, lateral rotation and forward rotation of femoral prosthesis will all increase the patello-femoral compressive force. And patellar thickening, patellar medial rotation, medial rotation and forward rotation of femoral prosthesis will also result in increase of ratio of patellar tendon force to quadriceps. And patellar medial rotation, medial rotation and forward rotation of femoral prosthesis will result in increase of patellar lateral translation.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2005; 6:6180-3. DOI:10.1109/IEMBS.2005.1615906
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