Early Clinical Outcomes of a New Posteriorly Stabilized Total Knee Arthroplasty Prosthesis: Comparisons with Two Established Prostheses

Abstract

PurposeWe sought to determine whether early clinical performance of new posterior stabilized (PS) knee system, the Vega-PS (Aesculap), is better than that of two established total knee arthroplasty (TKA) prostheses, the E.motion-PS (Aesculap) and the Genesis II (Smith & Nephew) in terms of functional outcomes, patient satisfaction, and incidence of adverse events.Materials and MethodsWe compared the clinical outcomes of 206 consecutive TKAs using Vega-PS with those of 205 TKAs using E.motion-PS and 216 TKAs using Genesis II at 2 years of follow-up.ResultsOverall, the knees with the Vega-PS had better functional outcome scores than the knees with the E.motion-PS, but had similar outcome scores to the knees with the Genesis II, as evident from the American Knee Society knee score (94.2 vs. 92.5 vs. 93.2), Western Ontario McMaster Universities Osteoarthritis (WOMAC) stiffness index (1.8 vs. 2.3 vs. 2.0), WOMAC function index (11.8 vs. 16.8 vs. 18.5), Short Form 36 (SF-36) physical component summary score (41.9 vs. 39.3 vs. 41.6), and SF-36 mental component summary score (50.0 vs. 45.8 vs. 46.9). Patient satisfaction was higher in the Vega-PS and Genesis II groups than the E.motion-PS group. No notable group differences were found in terms of the incidence of adverse events.ConclusionsThe Vega-PS, a newly developed PS fixed bearing prosthesis, had comparable or superior clinical performance in comparison with the two established fixed or mobile bearing PS prostheses.

Tibial Implant Fixation Behavior in Total Knee Arthroplasty: A Study With Five Different Bone Cements

“…These findings are in contrast to the promising short-term clinical behavior of the Vega PS knee system reported by Jain et al [44]. In 3 cohorts they compared the clinical outcomes of 206 consecutive TKAs using Vega PS with those of 2 clinically long-term established posterior-stabilized designs (e.motion PS n ¼ 205; Genesis II n ¼ 216) in a 2-year follow-up study and found comparable or superior functional clinical performance of Vega PS without incidence of implant-related adverse events [44]. Lionberger et al [48] further hypothesized that the ceramic hardened implant surface may be a potential factor for limited cement adhesion and early debonding in the later loosenings and proposed further testing to ascertain the root cause for these failures, but his cementation technique lists that he was using Palacos R and cementing in the late window we investigated in this study and he also lists 2 other cementation techniques that are specifically contrary to manufacturer recommendations.…”

“…They hypothesized that the new design of the Vega PS tibial tray may be a factor to be considered for their unfavorable clinical outcomes [48]. These findings are in contrast to the promising short-term clinical behavior of the Vega PS knee system reported by Jain et al [44]. In 3 cohorts they compared the clinical outcomes of 206 consecutive TKAs using Vega PS with those of 2 clinically long-term established posterior-stabilized designs (e.motion PS n ¼ 205; Genesis II n ¼ 216) in a 2-year follow-up study and found comparable or superior functional clinical performance of Vega PS without incidence of implant-related adverse events [44].…”

“…Under the aspect of clinical long-term behavior, the fatigue properties of the bone cements are of particular significance. Under flexural fatigue testing (ISO 16402:2008(E)) of bone cements, Palacos R with a remaining fatigue strength of 16.6 MPa at 10 7 cycles shows a significantly better fatigue performance than Surgical Simplex P (12.9 MPa at 10 7 cycles), whereas under quasi-static test conditions both cements are in a range of around 60 MPa [42,44]. The leading factor hereto is the molecular weight of the polymer powder and the cured bone cement, whereby sterilization by ethylene oxide has no influence on the molecular weight of the cement powder, but g-irradiation significantly reduces it [42].…”

Posterior-stabilized inserts are preferable to cruciate-substituting ultracongruent inserts due to more favourable kinematics and stability

“…PS inserts, which have a central polyethylene tibial post articulating with a transverse metal femoral cam, aim to decrease shear forces and wear via the physiologic rollback of the femur on the tibia and by improving anterior–posterior stability [14]. PS inserts provide reliable long‐term fixation and functional improvements [13, 19]. However, PS inserts can lead to unfavourable results, including intercondylar fracture of the distal femur, post‐breakage, post‐dislocation, and patellar clunk syndrome [9, 25].…”

Mid-term clinical and radiological results do not differ between fixed- and mobile-bearing total knee arthroplasty using titanium-nitride-coated posterior-stabilized prostheses: a prospective randomized controlled trial

“…Thus, enhancements in the range of motion (ROM) and deep knee flexion were expected from MB prostheses due to their more physiological kinematics [13]. However, previous randomized controlled trials [19, 22] and meta‐analyses [13, 17] comparing fixed‐bearing (FB) and MB TKA revealed no significant differences in the clinical or radiographic results, or survival rates, between these prostheses.…”