The knee prosthesis constraint dilemma: Biomechanical comparison between varus-valgus constrained implants and rotating hinge prosthesis. A cadaver study

The real degree of constriction of rotating hinge knee (RHK) and condylar con-strained prostheses (CCK) is a matter of discussion in revision knee arthroplasty.The objectives of this study are to compare the tibial rotation of both implantsand validate the use of inertial sensors with optical tracking system as movementmeasurement tools. A total of 16 cadaver knees were used. Eight knees werereplaced using a RHK (Endomodel LINK), and the remaining eight received a CCKprosthesis (LCCK, Zimmer). Tibial rotation range of motion was measured in fullextension and at 30°, 60°, and 90° of flexion, with four continuous waveforms foreach measurement. Measurements were made using two inertial sensors withspecific software and compared with measurements obtained using the goldstandard technique - the motion capture camera. The comparison of the accuracyof both measurement methods showed no statistically significant differencesbetween inertial sensors and motion capture cameras, withp>.1;themeanerrorfor tibial rotation was 0.21°. Tibial rotation in the RHK was significantly greaterthan in the CCK (5.25° vs. 2.28°, respectively),p<.05.WehaveshownthatRHKpermit greater tibial rotation, being closer to physiological values than CCKs.Inertial sensors have been validatedas an effective and accurate method ofmeasuring knee movement. The clinical significance: RHK appears to represent alower constriction degree than CCK systems.

The knee prosthesis constraint dilemma: Biomechanical comparison between varus-valgus constrained implants and rotating hinge prosthesis. A cadaver study Articles