Increased patellofemoral pressure after TKA: an in vitro study

Abstract

Despite correct implantation of the patellar implants and largely unchanged patellofemoral offset, a highly significant increase in pressure after patellar resurfacing was measured. Therefore, from a biomechanical point of view, the preservation of the native patella seems reasonable if there is no higher grade patellar cartilage damage.

Does patellofemoral congruence following total knee arthroplasty correlate with pain or function? Intraoperative arthroscopic assessment of 30 cases

“…While several authors quantified changes in retropatellar pressures in vitro (16)(17)(18)(19), to the authors' knowledge, there are no published studies that demonstrated whether such forces and pressures have any relation to pain or function. Patellar morphology is known to influence patellofemoral pressure (18,20,22), congruence (23,24) or instability (23,25), and while it is often associated with tilt (23,24), it does not necessarily correlate with poor outcomes (22,25).…”

“…Numerous authors observed that TKA increases patellofemoral pressures, particularly in mid-and late flexion (16)(17)(18)(19). Recent in vitro studies demonstrated that retro-patellar pressures are influenced by trochlear geometry, as well as the morphology of the native patella, or the shape of the patellar button (16)(17)(18)20).…”

“…Recent in vitro studies demonstrated that retro-patellar pressures are influenced by trochlear geometry, as well as the morphology of the native patella, or the shape of the patellar button (16)(17)(18)20). Furthermore, when the patella is not resurfaced, the extent of patellar cartilage erosion could affect the incidence of pain and revision (21).…”

“…Various studies investigated the influence of patellar morphology, using the Wiberg classification, on patellofemoral pressure (18,20,22), congruence (23,24) or instability (23,25). While patellar morphology is often associated with excessive tilt, Wiberg type C being most predisposed (23,24), it does not necessarily correlate with patellar subluxation or osteosclerosis (22,25), and pressure distribution data cannot be extrapolated to conclude on AKP or clinical outcomes.…”

The importance of the third knee compartment on outcome following total knee arthroplasty

“…The data were in contrast to the biomechanical findings reported by others. It has been shown that patellofemoral pressure increases up to 1.5-2.5 times after TKA in comparison with the natural knee [13]. Studies have also reported about the impact of the component design on femoropatella pressure [4].…”