A Performance Test to Assess Strategies to Transfer Weight During Knee Flexion and Extension With Rotation for Individuals With a Total Knee Replacement

Stability has been defined as the ability to transfer the vertical projection of the center of gravity to the supporting base and keep the knee as still as possible¹. The transfer of weight (load) to a single limb while still in double-stance is functional and simulates every day activities such as loading the dishwasher, transferring laundry, or reaching to pick up an item. Adding rotation in a transverse plane to this weight shift challenges knee stability, especially those with a total knee replacement (TKR). A clinical sign of laxity in mid-flexion indicates a risk for developing symptomatic instability; a common reason for TKR revision². Laxity is usually measured clinically in a single plane (anterior-posterior) and functionally with added turning maneuvers. Single-leg weight acceptance has been analyzed during athletic activities such as hopping, landing with cutting as well as in the older population with stair ascent and descent^3–5. Although single-leg performance tests are a good indicator of knee stability, weight shift during double-stance may be more functional for individuals with a TKR. A functional double-stance test should include both flexion/extension with rotation and loading. Our study utilizes a novel approach (Target Touch Task) in order to facilitate transfer of load to one extremity during squatting or extending while still in double-stance. The objective of this study was to identify strategies utilized by individuals with a TKR while in double-stance transferring load during rotational activities.