Quantifying patient recovery following Total Knee Arthroplasty (TKA) is vital for clinicians in planning rehabilitative protocols and tracking return to function. Patient knee extensor strength has been used to quantify rehabilitative success but lacks the patient perspective. The Forgotten Joint Score (FJS) is being used as an increasingly popular patient reported outcome measure (PROM) to gain additional understanding and include patient perspective regarding surgical outcomes. PURPOSE: To determine if the FJS can be a suitable predictor of patient performance in functional tests compared to a traditional objective measure, leg extensor strength, at 1-year following robotic-assisted TKA. METHODS: Twelve patients (height: 1.76 ± 0.1 m, mass: 85.5 ± 22 kg, BMI: 27 ± 5, age: 65 ± 6 years) 1-year postop from receiving a Posterior Stabilizing Total Knee implant with robotic-assisted surgery completed an FJS questionnaire, the Timed-up and go (TUG) test and the 30 second sit-stand-sit (STS) test followed by measuring peak knee extensor isometric strength. Both the operative and nonoperative leg were measured using a force transducer attached to the patient's ankle in a seated position. Leg extensor asymmetry (LEA) was calculated as the percent difference between the operative and nonoperative leg. RESULTS: Non-linear regression analysis for patient-reported FJS could explain 38% of the variance of the TUG (p = 0.046, significant) and 1% of the variance of the STS (p = 0.958, not significant). Non-linear regression model for the LEA explained 15% of the variance of the TUG (p = 0.45, not significant) and 57% of the variance of the STS (p = 0.02, significant). FJS explained 1% of the variance of the LEA (p = 0.91, not significant). FJS explained 5% of the variance in patient range of motion (ROM) (p = 0.32, not significant). CONCLUSION: Regression analysis of the FJS revealed high predictive value for the TUG, but not the STS, LEA or ROM. While the LEA revealed high predictive value for the STS, but not the TUG or ROM. FJS may not be sufficient to quantify patient recovery on its own, but when combined with more objectively measured variables like performance tests, ROM, and strength, PROMs may have the potential to provide clinicians with a more holistic understanding of patient recovery and function following robotic-assisted TKA.
IntroductionAccurate measurement of knee motion is necessary for assessment of natural joint function and in the diagnosis of pathology. In particular, precise knowledge of natural knee mechanics provides useful metrics for comparison to knee function following total knee arthroplasty (TKA). Reported measurements of natural knee kinematics during activities of daily living are rare, and often do not include both tibiofemoral (TF) and patellofemoral (PF) articulations. What's more, most studies record knee motion of younger subjects that are not necessarily representative of the age range associated with degenerative changes and TKA. The purpose of this study was to measure TF and PF kinematics of healthy older adults as they performed activities of daily living, including tasks considered more demanding for the knee [1].MethodsHigh speed stereo radiography (HSSR) was used to measure the kinematics of the PF and TF joints. HSSR utilizes two views of the knee to capture 3D sub-mm measurements accurate to wi...
