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Modulation and predictors of periprosthetic bone mineral density following total knee arthroplasty.

Mau-Moeller A, Behrens M, Felser S, Bruhn S, Mittelmeier W, Bader R, Skripitz R - Biomed Res Int (2015)

Bottom Line: BMD of the distal femur was significantly reduced by 19.7% (P = 0.008) 3 months after surgery, while no changes were found in BMD of the tibia.The results of SEM demonstrate that 55% of the BMD variance was explained by the model (χ(2) = 0.002; df = 1; P = 0.96; χ(2)/df = 0.002; RMSEA < 0.01; TLI = 1.5; CFI = 1.0).A significant direct effect was only evidenced by the variable lean mass (β = 0.38; b = 0.15; SE = 0.07; C.R. = 2.0; P = 0.046).

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics, University Medicine Rostock, Doberaner Straße 142, 18057 Rostock, Germany ; Department of Exercise Science, University of Rostock, Ulmenstraße 69, 18057 Rostock, Germany.

ABSTRACT
Total knee arthroplasty (TKA) leads to a loss of periprosthetic bone mineral density (BMD). Great importance is attached to the prevention of periprosthetic bone loss with a view to ensuring a long service life of the prosthesis. In order to provide appropriate recommendations for preventive movement therapy measures to combat peri-implant bone loss, it is necessary to know the predictors of periprosthetic BMD. The aim of this study was (1) to determine the change of periprosthetic BMD of the femur and tibia and (2) to analyse the effects of different predictors on periprosthetic BMD. Twenty-three patients with primary TKA were evaluated 10 days and 3 months postoperatively. The data analysis comprised (1) the change in periprosthetic BMD from pretest to posttest and (2) the correlations between BMD and the variables isometric maximum voluntary force, lean mass, physical activity (step count), and BMI using multiple linear regression and structural equation modelling (SEM). BMD of the distal femur was significantly reduced by 19.7% (P = 0.008) 3 months after surgery, while no changes were found in BMD of the tibia. The results of SEM demonstrate that 55% of the BMD variance was explained by the model (χ(2) = 0.002; df = 1; P = 0.96; χ(2)/df = 0.002; RMSEA < 0.01; TLI = 1.5; CFI = 1.0). A significant direct effect was only evidenced by the variable lean mass (β = 0.38; b = 0.15; SE = 0.07; C.R. = 2.0; P = 0.046). It can be assumed that a large muscle mass with accompanying distribution of high mechanical load in the bones can contribute to local changes of periprosthetic BMD. Concrete recommendations for preventing peri-implant bone loss therefore include exercises which have the aim of maintaining or building up muscle mass.

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A priori structural equation model. BMD, periprosthetic bone mineral density; iMVF, isometric maximum voluntary force. Chi-square (χ2) = 0.002; degrees of freedom (df) = 1; χ2/df = 0.002; root mean square error of approximation <0.01; Tucker-Lewis index = 1.46; comparative fit index = 1.00. Significant path coefficients are indicated in blue (P ≤ 0.050).
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fig2: A priori structural equation model. BMD, periprosthetic bone mineral density; iMVF, isometric maximum voluntary force. Chi-square (χ2) = 0.002; degrees of freedom (df) = 1; χ2/df = 0.002; root mean square error of approximation <0.01; Tucker-Lewis index = 1.46; comparative fit index = 1.00. Significant path coefficients are indicated in blue (P ≤ 0.050).

Mentions: For the SEM, the direct and indirect effects of the independent variables step count and BMI—as well as the intervening variables iMVF and lean mass—on periprosthetic BMD of the femur were analysed. The SEM with the relationships between the variables was made clear a priori in graphical terms by a path diagram (Figure 2).


Modulation and predictors of periprosthetic bone mineral density following total knee arthroplasty.

Mau-Moeller A, Behrens M, Felser S, Bruhn S, Mittelmeier W, Bader R, Skripitz R - Biomed Res Int (2015)

A priori structural equation model. BMD, periprosthetic bone mineral density; iMVF, isometric maximum voluntary force. Chi-square (χ2) = 0.002; degrees of freedom (df) = 1; χ2/df = 0.002; root mean square error of approximation <0.01; Tucker-Lewis index = 1.46; comparative fit index = 1.00. Significant path coefficients are indicated in blue (P ≤ 0.050).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4352471&req=5

fig2: A priori structural equation model. BMD, periprosthetic bone mineral density; iMVF, isometric maximum voluntary force. Chi-square (χ2) = 0.002; degrees of freedom (df) = 1; χ2/df = 0.002; root mean square error of approximation <0.01; Tucker-Lewis index = 1.46; comparative fit index = 1.00. Significant path coefficients are indicated in blue (P ≤ 0.050).
Mentions: For the SEM, the direct and indirect effects of the independent variables step count and BMI—as well as the intervening variables iMVF and lean mass—on periprosthetic BMD of the femur were analysed. The SEM with the relationships between the variables was made clear a priori in graphical terms by a path diagram (Figure 2).

Bottom Line: BMD of the distal femur was significantly reduced by 19.7% (P = 0.008) 3 months after surgery, while no changes were found in BMD of the tibia.The results of SEM demonstrate that 55% of the BMD variance was explained by the model (χ(2) = 0.002; df = 1; P = 0.96; χ(2)/df = 0.002; RMSEA < 0.01; TLI = 1.5; CFI = 1.0).A significant direct effect was only evidenced by the variable lean mass (β = 0.38; b = 0.15; SE = 0.07; C.R. = 2.0; P = 0.046).

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics, University Medicine Rostock, Doberaner Straße 142, 18057 Rostock, Germany ; Department of Exercise Science, University of Rostock, Ulmenstraße 69, 18057 Rostock, Germany.

ABSTRACT
Total knee arthroplasty (TKA) leads to a loss of periprosthetic bone mineral density (BMD). Great importance is attached to the prevention of periprosthetic bone loss with a view to ensuring a long service life of the prosthesis. In order to provide appropriate recommendations for preventive movement therapy measures to combat peri-implant bone loss, it is necessary to know the predictors of periprosthetic BMD. The aim of this study was (1) to determine the change of periprosthetic BMD of the femur and tibia and (2) to analyse the effects of different predictors on periprosthetic BMD. Twenty-three patients with primary TKA were evaluated 10 days and 3 months postoperatively. The data analysis comprised (1) the change in periprosthetic BMD from pretest to posttest and (2) the correlations between BMD and the variables isometric maximum voluntary force, lean mass, physical activity (step count), and BMI using multiple linear regression and structural equation modelling (SEM). BMD of the distal femur was significantly reduced by 19.7% (P = 0.008) 3 months after surgery, while no changes were found in BMD of the tibia. The results of SEM demonstrate that 55% of the BMD variance was explained by the model (χ(2) = 0.002; df = 1; P = 0.96; χ(2)/df = 0.002; RMSEA < 0.01; TLI = 1.5; CFI = 1.0). A significant direct effect was only evidenced by the variable lean mass (β = 0.38; b = 0.15; SE = 0.07; C.R. = 2.0; P = 0.046). It can be assumed that a large muscle mass with accompanying distribution of high mechanical load in the bones can contribute to local changes of periprosthetic BMD. Concrete recommendations for preventing peri-implant bone loss therefore include exercises which have the aim of maintaining or building up muscle mass.

Show MeSH
Related in: MedlinePlus