The relationship between lower extremity swelling, quadriceps strength, and functional performance following total knee arthroplasty

Abstract

Background: The relationships between swelling after total knee arthroplasty (TKA) and quadriceps strength and functional performance are poorly understood. Therefore, the aim of this study was to examine the relationships between lower extremity swelling, measured using bioelectrical impedance assessment (SF-BIA), and quadriceps strength and timed up and go (TUG) times following TKA.

Methods: 53 participants (64 ± 9.5 y/o, 43% male) undergoing primary unilateral TKA were recruited for the longitudinal observational study with repeated measures. Quantities of swelling were examined for contribution to two and six-week outcomes of strength and TUG time using hierarchical regression controlling for age, sex, and the baseline value of the dependent variable. Swelling was assessed using bioelectrical impedance assessment and quantified as the peak level of swelling and cumulative swelling (integral) over the post-TKA time window. Maximum isometric quadriceps strength (MVIC) was measured using a electromechanical dynamometer and participant functional performance measured using the TUG.

Results: Neither peak swelling nor cumulative swelling significantly contributed to the variance of two-week quadriceps strength. At six weeks, peak swelling significantly improved the variance in maximal quadriceps strength by an additional four percent (p = 0.05), while cumulative swelling did not significantly contribute. Peak swelling significantly contributed to the variance in two-week (16%) and six-week (five percent) TUG times (p < 0.05), but the cumulative swelling did not.

Conclusions: Peak swelling represents a value of post-TKA swelling that is associated with strength and function. Reducing the peak level of swelling, occurring early after surgery, may improve patient functional recovery.

Level of evidence: Level II - Prospective observational study.

Conflict of interest statement

Conflict of Interest Statement:

Copyright © 2019 Elsevier B.V. All rights reserved.

Figures

Figure 1.

Examples of the calculation of A) Early cumulative swelling (integral of ~14 days) and B) full cumulative swelling (integral of ~ 42 days) using trapezoidal integration.

Figure 2.

Relationship between peak swelling and A) two-week TUG time and B) six-week TUG time from the linear model when controlling for baseline TUG time, age, and sex.