Abstract
Introduction:
Non-hinged constrained condylar components (CCK) may be used for primary TKA in presence of severe deformity, fixed contractures and ligamentous laxity. Several authors have recommended use of stem extensions to accompany CCK type of components. However, use of stem extensions in primary TKA, not only invades the medullary canal, but may also be associated with increased surgical time, implant cost, and thigh or leg pain. The purpose of this study was to assess the short-term outcomes of primary CCK knees without stem extensions and to compare this to a control group of standard posterior stabilized (PS) knees, otherwise using the same implant design.
Materials and Methods:
We retrospectively reviewed the clinical and radiographic data on 503 consecutive TKA's performed by 2 arthroplasty surgeons at the same institution between 2008–2010. Surgical technique, implant type, bone-cement and cementation technique was similar. The only difference between groups was the use of CCK polyethylene insert in one group and a PS insert in the other. Knee society scores (KSS) were used to determine pain, function and ROM. Radiographic evaluation was done using the knee society's criteria to determine implant fixation. Failure was defined as revision for any reason. Statistical analyses were performed using SPSS software.
Results:
There were 250 primary CCK (2–3 degrees of varus-valgus and rotational constraint) and 253 PS knees (7–8 degrees of varus-valgus and rotational constraint) with a mean follow-up of 3.1 years in the study cohort. Both groups had similar patient demographics, preoperative tibio-femoral alignment and KSS. Postoperative component alignment, tibio-femoral alignment, poly thickness, ROM, KSS, prevalence of radiolucent lines and revision rates were similar. No difference was found specifically for aseptic loosening between groups.
Discussion:
Use of stem extensions may not be needed despite use of CCK in primary cemented TKA.
