No clinical differences at the 2-year follow-up between single radius and J-curve medial pivot total knee arthroplasty in the treatment of neutral or varus knees

Abstract

PurposeModern total knee arthroplasty (TKA) systems are designed to reproduce the normal knee kinematics and improve patient outcome. The authors compared two different third‐generation medial pivot TKA implants, having a single‐radius or a J‐curve design in their sagittal plane, hypothesizing no clinical differences. MethodsTwo cohorts of 50 patients who underwent primary TKA were first preoperatively matched by sex, deformity, body mass index (BMI), Oxford Knee Score (OKS), Knee society score (KSS) and range of motion (ROM) and then statistically analyzed at a minimum follow‐up (FU) of 2 years. An identical surgical technique, which aimed to reproduce a slightly tighter medial than lateral compartment, was used in all knees. ResultsAt a minimum follow‐up of 2 years (range 24–34 months) there were no statistically significant differences in OKS and KSS between the two implant groups. The final ROM differed statistically between the two groups: the average maximum active flexion was 123° in the J‐curve femoral design group with an adapted “medially‐congruent” polyethylene insert, and 116° in the single radius femoral design with a medial “ball‐in‐socket” articulation. ConclusionNo clinical and radiological differences were found when the two cohorts of patients were compared. This study showed that the implant design played a minor role in the final outcome as opposed to a precise surgical technique. Level of evidenceRetrospective case‐control study, Level III.

Kinematic Comparison between Medially Congruent and Posterior-Stabilized Third-Generation TKA Designs

“…Acknowledging these limitations, the results of this study are consistent with the experimental work of the current and other authors [11,17,[20][21][22][23][24]27,34,38], where contemporary pivoting, fixed-bearing TKA designs have failed to reproduce normal knee kinematics [43]. On the other hand, the TKA pivoting design evaluated in this study and other dual-pivoting designs studied by different authors have demonstrated bettercontrolled kinematics that are correlated to better active flexion [23] and better functional muscle coordination [44,45], favoring clinically detectable improved knee stability.…”

“…Acknowledging these limitations, the results of this study are consistent with the experimental work of the current and other authors [11,17,[20][21][22][23][24]27,34,38], where contemporary pivoting, fixed-bearing TKA designs have failed to reproduce normal knee kinematics [43]. On the other hand, the TKA pivoting design evaluated in this study and other dual-pivoting designs studied by different authors have demonstrated bettercontrolled kinematics that are correlated to better active flexion [23] and better functional muscle coordination [44,45], favoring clinically detectable improved knee stability. From a purely surgical perspective, after a precise surgical balancing of ligaments and soft tissues has been obtained, the medial-conforming design studied in this comparative series, characterized by a 1:1 medial compartment radius ratio and correlated to the asymmetrical tibial baseplate, gives a clear technical advantage in the correct reproduction of the medial dwell point of a natural knee.…”

“…All patients received a third-generation TKA design (Persona, Zimmer-Biomet, Warsaw, IN, USA) performed by a single surgeon (PFI) who had more than five years of clinical experience with the system at the beginning of the current study [ 21 , 22 , 23 ]. This TKA system has two options for the J-curve femoral design (posterior-stabilized (PS) and cruciate-retaining (CR)) and a single anatomical tibial baseplate that allows us to use two different polyethylene inserts: PS (for the PS femur) and medially congruent (MC; when a CR femur is selected).…”

“…The reproduction of these dual pivoting kinematics is extremely challenging since the anterior cruciate ligament (ACL), which is routinely removed during TKA, plays a major role in normal knee mechanics [ 20 ]. The current authors have previously described a surgical technique [ 21 ], adapted to a third-generation TKA medial pivot design [ 22 , 23 ], that has shown very satisfactory results when compared to other classical techniques and posterior-stabilized implants [ 11 ].…”

Sensor-guided technology helps to reproduce medial pivot kinematics in total knee arthroplasty

“…10,11 Despite these advancements in TKA design, which aimed to reproduce a more anatomical kinematic, there is evidence that implant design plays a minor role in the final outcome as opposed to a precise surgical technique. 12 Therefore, proper balancing of soft tissue has become of primary importance as it is estimated that improper balancing causes up to 35% of TKA revisions in the United States. [13][14][15] To address this problem and to make ligament balancing less operator dependent, several advances in technology have been proposed over the past decades.…”