Evolution of customization design for total knee arthroplasty.

Total Knee Arthroplasty (TKA) is a highly successful surgical procedure with more than 600,000 TKA's performed annually in the US. Interest in improving surgical outcomes has led to improvements in surgical technique, instrumentation, and implant design. Computer navigation and robotic systems were introduced to further refine the mechanical alignment of joint replacement procedures.

Unicompartmental knee resurfacing: enlarged tibio-femoral contact area and reduced contact stress using novel patient-derived geometries.

Advances in imaging technology and computer-assisted design (CAD) have recently enabled the introduction of patient-specific knee implant designs that hold the potential to improve functional performance on the basis of patient-specific geometries, namely a patient-specific sagittal and coronal curvature, as well as enhanced bone preservation. The objective of this study was to investigate the use of a novel implant design utilizing a patient specific sagittal J-curve on the femoral component combined with a novel constant, patient-derived femoral coronal curvature and to assess tibio-femoral contact area and contact stress on a femur matched curved tibial polyethylene insert. Mean contact area and standard deviations were 81+/-5, 96+/-5 and 74+/-4 mm(2) for the heel strike, toe off and mid-stance positions, respectively.

Osteolysis after total knee arthroplasty.

Osteolysis ranks as the most significant cause of revision surgery in both total hip arthroplasty and total knee arthroplasty (TKA). The factors leading to osteolysis in TKA are unique and sometimes preventable. Changes in polyethylene manufacturing and implant design are striving to improve overall wear.

Patellar crepitation in the P.F.C. sigma total knee system.

Painless and painful patellar crepitation and patellar clunk syndrome represent a spectrum of peripatellar scar formation particular to posterior-stabilized knee components, although it may occur with cruciate-retaining designs as well. The formation of peripatellar inflammatory scar tissue is related to implant design and surgical technique, with microscopic and gross findings indicating varying degrees of inflammatory fibrous hyperplasia. These well recognized clinical entities have an incidence ranging between 1% and 5% in different series.

Tibial forces measured in vivo after total knee arthroplasty.

An instrumented tibial prosthesis was developed to measure forces in vivo after total tibial arthroplasty. This prosthesis was implanted in a 67-kg, 80-year-old man. The prosthesis measured forces at the 4 quadrants of the tibial tray.