Medial congruent polyethylene design show different tibiofemoral kinematics and enhanced congruency compared to a standard symmetrical cruciate retaining design for total knee arthroplasty—an in vivo randomized controlled study of gait using dynamic radiostereometry

Abstract

Purpose New total knee arthroplasty implant designs attempt to normalize kinematics patterns that may improve functional performance and patient satisfaction. It was hypothesized that a more medial congruent (MC) anatomic bearing design (1) inluences the tibiofemoral kinematics and (2) enhances articular congruency compared to a standard symmetrical cruciate retaining (CR) bearing design. Methods In this double-blinded randomized study, 66 patients with knee osteoarthritis were randomly included in two groups: MC (n = 31) and CR (n = 33). Clinical characteristics such as knee ligament lesions and knee osteoarthritis scores were graded on preoperative magnetic resonance imaging and radiography. At the 1-year follow-up, dynamic radiostereometric analysis was used to assess tibiofemoral joint kinematics and articulation congruency. Patient-reported outcome measures, Oxford Knee Score, the Forgotten Joint Score, and the Knee Osteoarthritis Outcome Score, were assessed preoperatively and at the 1-year follow-up. Results Compared to the CR bearing, the MC bearing displayed an ofset with approximately 3 mm greater anterior tibial drawer (p < 0.001) during the entire motion, and up to approximately 3.5 degrees more tibial external rotation (p = 0.004) from mid-swing to the end of the gait cycle at the 1-year follow-up. Furthermore, the congruency area in the joint articulation was larger during approximately 80% of the gait cycle for the MC bearing compared to the CR. The patient-reported outcome measures improved (p < 0.001), but there were no diferences between groups. In addition, there were no diferences in clinical characteristics and there were no knee revisions or recognized deep infections during follow-up. ConclusionThe study demonstrates that the MC-bearing design changes tibiofemoral kinematics and increases the area of congruency towards more native knee kinematics than the CR bearing. In perspective this may contribute to a more stabilized knee motion, restoring the patient's conidence in knee function during daily activities.

Dynamic radiostereometry can objectively quantify the kinematic laxity patterns and rotation instability of the knee during a pivot‐shift test

“…The clinical application of the precise, accurate and radiation low‐dose dRSA imaging method for the assessment of knee kinematics with the pivot‐shift test is limited to small‐scale experimental or clinical studies, such as for evaluating new surgical methods [3, 10, 21, 22, 39, 40, 48]. There are several reasons, including that image analyses are user‐intensive, and there is a need for a surgeon/specialist to perform the pivot‐shift test during imaging with radiation dose being applied to the surgeon's hands (although minimised with the use of lead gloves).…”

PCL retention demonstrates better functional scores and gait patterns in total knee arthroplasty using a medial congruent insert—a prospective study

“…Jones et al reported better sagittal stability using an MC insert [11]. Petersen et al [18], Shi et al [21] and Cacciola et al [4] also report better stability and excellent clinical and patient reported outcomes in patients undergoing TKA using a medial pivot insert. Sabatini et al [20] similarly reported good to excellent results using a third‐generation prosthesis system with a MC polyethylene insert.…”

“…Several authors have reported on the rationale behind the evolution of the MC polyethylene insert design in providing a greater level of stability with minimum constraint [9, 18, 21]. Alesi et al [1].…”

“…The MC insert with a medial “ball and socket” design provides medial conformity, anterior constraint and stability while allowing rotational freedom in the lateral compartment. These features attempt to approximate normal knee biomechanics [8, 18]. The improved articular geometry reduces polyethylene wear by minimizing contact force concentration and condylar lift‐off [19, 25].…”

Posterior Cruciate Ligament Preservation versus Posterior Cruciate Ligament Sacrifice: Comparing Patient Outcomes in Medial Congruent Total Knee Arthroplasty

“…Additional evidence from Sun et al 10 and Konno et al 11 indicates that congruent inserts decrease patellofemoral pressures, mimic near-normal joint kinematics, and reduce the risk of patellofemoral complications. Enhanced anteroposterior stability is a distinct advantage of the MC articulation, which also diminishes the likelihood of anterolateral pain post-TKA 7,12,13 . Nishio et al 14 conducted an investigation utilizing a CT-based navigation system to examine intraoperative kinematics, finding that PROMs, including functional activities and patient satisfaction, fared better with a medial pivot insert.…”