Constrained prosthesis in primary total knee arthroplasty.

Abstract

Background: This paper presents the functional results and indication criteria for prostheses for total knee arthroplasty with more constraint than posterior stabilization more constraint than posterior-stabilized. Methods: Retrospective analysis of 43 TKA in 40 patients with an average follow up of 6.2 years. The preoperative diagnoses were valgus osteoarthritis in 38 cases and varus in 5. We classified the sufficiency of the collateral ligaments as sufficient, attenuated or incompetent. We developed a classification system for the valgus Osteoarthritis, which related the type of knee with the selected prosthesis. Results: Posterior-stabilized plus implants were used in 28 cases, with an average alignment of 15.9°: 26 were valgus knees, 21 of which presented sufficient and 5 attenuated ligaments. Constrained prosthesis were used in 7 patients with an average valgus alignment of 21.6°, (2 with sufficient and 5 with attenuated ligaments.) Rotating-Hinge prosthesis were used in 8 patients, 5 with an average valgus alignment of 24.6 ° (3 of them associated to recurvatum), 4 with incompetent ligaments and one with attenuated ligaments. Conclusions: We recommend using: Posterior-stabilized plus implants in deformities lower than 20°, with sufficient collateral ligaments and no bone defects; constrained prosthesis in patients with greater deformity (>20°) with collateral ligaments with some degree of sufficiency (attenuated at the most); and rotating-hinge implants in knees with collateral or multidirectional ligament insufficiency, associated with recurvatum, significant bone defects or severe deformities in rheumatoid arthritis or neuropathic origin.

Keywords

• genu valgo
• recurvatum
• inestabilidad
• constreñido
• bisagra rotatoria. Valgus
• recurvatum
• instability
• constrained prosthesis
• rotating-hinge implants.