Longitudinal Course of Physical Function in People With Symptomatic Knee Osteoarthritis: Data From the Multicenter Osteoarthritis Study and the Osteoarthritis Initiative

Abstract

Objective Pain and functional decline are hallmarks of knee osteoarthritis (OA). Nevertheless, longitudinal studies unexpectedly reveal stable or improved physical function. The aim of this study was to impute missing and pre–total knee replacement (TKR) values to describe physical function over time among people with symptomatic knee OA. Methods We included participants from the Multicenter Osteoarthritis Study (MOST) and the Osteoarthritis Initiative (OAI) with incident symptomatic knee OA, observed during the first 30 months in MOST and 36 months in OAI. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function (WOMAC-PF), the 5-times sit-to-stand test, and the 20-meter-walk test were assessed at 4 and 5 years in MOST and at 6 years in OAI. We used a multiple imputation method for missing visits, and estimated pre-TKR values close to the time of TKR, using a fitted local regression smoothing curve. In mixed-effect models, we investigated the physical function change over time, using data before and after imputation and calculation of pre-TKR values. Results In MOST, 225 (8%) had incident knee OA, with corresponding 577 (12.7%) in OAI. After adjusting for pre-TKR values and imputing missing values, we found that WOMAC-PF values remained stable or slightly declined over time, and the 20-meter-walk test results changed from stable in nonimputed analyses to worsening using imputed data. Conclusion Data from MOST and OAI showed stable to worsening physical function over time in people with incident symptomatic knee OA after imputing missing values and adjusting pre-TKR values.

Risk of Knee Osteoarthritis Over 24 Months in Individuals Who Decrease Walking Speed During a 12-Month Period: Data from the Osteoarthritis Initiative

“…It is possible that important potential confounders exist for the relationship between walking speed and incident rKOA that were not measured in OAI. Multiple previous studies 15,16,28 have been published using the 20-meter walk times from the OAI, yet we are not aware of any published reliability data on this physical function outcome at the different OAI sites. While measuring 20-meter self-selected walking pace is a commonly collected clinical outcome of physical performance, a previous study has described a learning effect where individuals with rKOA walk faster in the first of three 20-meter walking trials compared to the subsequent two.…”

“…14 Participants were instructed to walk at their usual walking speed from the start to finish points of marked 20-meter distance. 15 As previously reported, 15,16 2 trials were collected and the mean of these trials was used for data analysis. We included two periods of exposure assessment to determine change in walking speed, resulting in two potential observations for each participant.…”

Improvements in physical function and pain sustained for up to 10 years after knee or hip arthroplasty irrespective of mental health status before surgery

“…This is consistent with findings from the MOST and OAI studies (Øiestad et al. 2016). Recovery rates for physical function were over 80% in those with TKA or THA, which is in the same range as previously reported recovery rates (i.e.…”

The quality-of-life burden of knee osteoarthritis in New Zealand adults: A model-based evaluation

“…[ 19 ] Subjects with knee OA were initialised with a mean WOMAC pain score of 30 (standard deviation 15), and an increase of 0.5 points (standard deviation 5) for each subsequent year. The mean WOMAC pain level of 30, based on cohort research data,[ 20 , 21 ] was used to generate a cohort with mild to moderate pain from knee OA with substantial variation around the mean. The subsequent year increase in pain was used to give subjects a relatively stable pain trajectory over the course of their OA progression.…”