Comparison of Revision Rates of Non-modular Constrained Versus Posterior Stabilized Total Knee Arthroplasty: a Propensity Score Matched Cohort Study

Abstract

Background: Attaining stability during total knee arthroplasty (TKA) is essential for a successful outcome. Although traditional constrained total knee prostheses have generally been used in conjunction with intramedullary stems, some devices have been widely used without the use of stems, referred to as non-modular constrained condylar total knee arthroplasty (NMCCK). Questions/Purposes: The aim of this study was to compare revisions rates after total knee replacement with a non-modular constrained condylar total knee (NMCCK) compared to a posterior-stabilized (PS) design. Methods: Between 2007 and 2012, primary PS total knees were compared with NMCCK implants from the same manufacturer. Propensity score matching was performed, and implant survivorship was examined using a Cox proportional hazards model. The cohort consisted of 817 PS knees and 817 NMCCKs matched for patient demographics, surgeon volume, and pre-operative diagnosis. Results: All cause revisions occurred in 11 of 817 (1.35%) in the PS group compared to 28 of 817 (3.43%) in the NMCCK group (p = 0.0168). Excluding revisions for infection and fracture, 8 of 817 (0.98%) PS knees required revision for mechanical failure compared to 18 of 817 (2.20%) NMCCK knees (p = 0.0193). Conclusions: While revisions rates in both cohorts were low, there was a significantly higher revision rate with NMCCKs. Given that cases requiring the use of NMCCK implants are likely more complex than those in which PS implants are used, our findings support the judicious use of NMCCK prostheses.

Failure After Modern Total Knee Arthroplasty: A Prospective Study of 18,065 Knees

“…This may be due to those patients with CCK implants having poor bone stock, ligamentous deficiency, or large preoperative deformities. A large proportion of the CCK TKAs that failed in our series was a specific non-modular CCK without stem extensions that may be predisposed to aseptic loosening of the femoral component [19]. Previous literature provided evidence that use of a second generation CCK implant in primary TKA is safe in the short to medium follow up period [20][21] [22], but contradictory reports exist that in long-term follow up, CCK implants have higher complication rates and decreased survival compared to standard TKAs, but again the majority of patients with a CCK primary TKA implant may have severe deformity or instability pre-operatively [23].…”

Clinical and Functional Outcomes: Primary Constrained Condylar Knee Arthroplasty Compared With Posterior Stabilized Knee Arthroplasty

“…There is no need to recut the femur or use stems because of a common femoral box cut across different levels of constraint, which may be used without femoral or tibial stems. 6 , 21 Moussa et al 22 reported that there is an increased revision rate in a stemless constrained condylar prosthesis compared with a PS prosthesis. The basic tenets of careful soft-tissue balancing for stable total knee arthroplasty with equal flexion and extension gaps still hold true; however, a case can be made for the routine use of a more constrained prosthesis, such as a CCK prosthesis, prophylactically.…”

Early Clinical and Radiological Outcomes of the Metaphyseally Fixed Totally Stabilized Knee Prosthesis in Primary Total Knee Arthroplasty

“…14,35,37 However, some studies have cautioned against higher aseptic loosening rates in the use of similar stemless VVC knee implants in the primary setting. [41][42][43] The findings of these studies, however, should be interpreted with caution as they have the same VVC implant design in common. The predominant cause of failure in these studies was femoral component loosening.…”