Abstract
Long-term implant failure in the form of aseptic loosening and periprosthetic fracture is the most common cause of revision procedures in total knee arthroplasty (TKA). While early loosening can often be attributed to failure of primary fixation, late implant failure could be associated with loss of fixation secondary to bone resorption, as a result of stress shielding in the proximal tibia. This current review study was performed to identify the clinical effects of different implant-, patient-, and surgery-related biomechanical factors on TKA-related tibial bone loss in clinical reality. Implant-related factors considered were the fixation method, and the implant type, geometry, and stiffness. In terms of patient characteristics, the effects of age, sex, knee alignment, bone density, body weight, and activity level were analyzed. The clinical literature on these topics mostly concerned longitudinal radiographic studies investigating the effect of a single factor on changes in the proximal tibia over time using bone densitometry. Implant stiffness, implant geometry and knee alignment were the only factors consistently found to affect regional bone density changes over time. Each clinical study used its own specific study design, with different definitions used for the baseline density, time points of baseline and follow-up measurements, and regions of interest. Due to the differences in study design, direct comparison between the clinical impact of different biomechanical factors was not possible. Based on the findings over the densitometry studies, a standardized guideline was proposed to allow reliable comparison between consistently reported outcome of future radiographic TKA studies.
Highlights
Total knee arthroplasty (TKA) is one of the most successful surgical interventions, but the number of primary TKA failures is increasing as a result of the aging population and the acceptance of TKA in younger patients [1]
Based on the different used methods and findings over the studies, conclusions were drawn on the effects of the discussed factors on long-term bone density outcome, and recommendations were provided for future densitometry studies regarding study design and reporting of relevant data
Studies covering the effects of multiple factors on bone density changes have been reviewed more than once over this section
Summary
Total knee arthroplasty (TKA) is one of the most successful surgical interventions, but the number of primary TKA failures is increasing as a result of the aging population and the acceptance of TKA in younger patients [1]. Two common causes of long-term tibial implant failure are aseptic loosening and periprosthetic fracture [1, 2], which can be linked to stress shielding-related osteolysis observed around the implant [3]. Due to an alteration of stress distribution in the bone after TKA, by the introduction of a homogenous. 1 3 implant and change in physiological loading, adaptive bone remodeling will take place over time following Wolff’s law [4], which typically leads to periprosthetic bone resorption [5]. Many longitudinal clinical studies have been conducted on postoperative bone changes, by measuring bone density in the proximal tibia over time. The goal of most studies was to establish the effect of a single factor in TKA on subsequent regional density changes as a result of bone remodeling
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