A Decline in Walking Speed Is Associated With Incident Knee Replacement in Adults With and at Risk for Knee Osteoarthritis

Causal effects of walking pace on osteoarthritis: a two-sample mendelian randomization study

Background: Osteoarthritis (OA) is one of the most common joint diseases worldwide, imposing a substantial burden on individuals and society. Numerous pieces of evidence suggest that walking pace (WP) can serve as a predictive indicator for the risk of various diseases, and observational studies have also found a potential link between WP and the risk of OA. However, the causal relationship between WP and the risk of OA remains unclear. Methods: We conducted a mendelian randomization (MR) study using data from the European Genome-wide Association Study, which included WP (including 459,915 participants), OA (including 10,083 cases and 40,425 controls), knee OA (including 24,955 cases and 378,169 controls), and hip OA (including 15,704 cases and 378,169 controls). Single nucleotide polymorphisms (SNPs) associated with WP were utilized to infer causal associations with OA and its subtypes. The Inverse Variance Weighted (IVW) technique served as the primary causal analysis method. Three auxiliary MR methods - MR-Egger, weighted median, and maximum likelihood - were used to substantiate the IVW results. Sensitivity analyses were performed to examine heterogeneity and pleiotropy. In addition, multivariate MR (MVMR) analysis was used to assess causality after adjustment for three potential confounders. Results: According to the results of the IVW method, every 1 standard deviation increased in genetic WP corresponds to an 89% reduction in the risk of OA (odds ratio (OR) = 0.11; 95% confidence interval (CI), 0. 06-0.19; p = 1.57 × 10-13), an 83% reduction in the risk of knee OA (OR = 0.17; 95% CI, 0.11-0.28; p = 2.78 × 10-13), and a 76% reduction in the risk of hip OA (OR = 0.24; 95% CI, 0.14-0.43; p = 1.51 × 10-6). These results were confirmed by the three additional MR methods and validated by the sensitivity analysis. Ultimately, the MVMR analysis confirmed that the role of WP in reducing the risk of OA and its subtypes remains consistent regardless of potential confounders. Conclusion: The results of our MR study highlight a significant causal association between WP and the susceptibility to OA, including its knee and hip subtypes. These findings propose that WP could be utilized as a potential prognostic factor for OA risk.

Knee symptoms do not affect walking biomechanics among women 6 months after anterior cruciate ligament reconstruction

Women with anterior cruciate ligament reconstruction report worse pain and knee-related symptoms, and also exhibit biomechanical changes that may be related to knee osteoarthritis (OA) development. This is particularly concerning as symptom state has been previously associated with knee OA development. The purpose of this study was to compare lower extremity walking biomechanics between women (age: 21.40 ± 8.54 years) experiencing clinically significant knee-related symptoms and women with acceptable symptoms 6 months following surgery. Twenty-eight women with history of primary, unilateral anterior cruciate ligament reconstruction who completed a lower extremity walking biomechanics assessment 6 months following surgery were included in this analysis. Women were dichotomized as experiencing acceptable or clinically significant knee symptoms according to Knee injury and OA Outcomes Score cut-offs described by Englund et al. Walking biomechanics were compared between women with clinically significant and acceptable symptoms using one-way analysis of covariances for involved limb biomechanics. Biomechanical variables of interest were: peak vertical ground reaction forces (vGRFs), vGRF loading rates, knee flexion angles, knee extension moments, knee adduction angles, and knee adduction moments, and gait speed. Nearly 60% of women reported clinically significant knee symptoms 6 months postoperative. There were no statistically significant differences between symptom groups for walking biomechanics and gait speed outcomes. These findings suggest patient reported knee symptoms may not be a primary influence on walking biomechanics 6 months following anterior cruciate ligament reconstruction. Though, longitudinal assessment of changes in symptom state and walking biomechanics may be warranted as poorer walking biomechanics and symptoms are indicators of knee OA.

A Narrative Review on Measurement Properties of Fixed-distance Walk Tests Up to 40 Meters for Adults With Knee Osteoarthritis

Knee osteoarthritis (OA) is a serious disease and has no cure to date. Knee OA is a leading cause of functional limitation (e.g., difficulty walking). Walking speed is 1 method of quantifying difficulty with walking and should be assessed in clinical practice for adults with knee OA because it has prognostic value and is modifiable. Specifically, slow walking speed is associated with increased risk of adverse health outcomes, including all-cause mortality in adults with knee OA and can be modified by engaging in physical activity or exercise. However, at present, there is little consensus on the distance and instructions used to conduct the walk test. Distance is often selected based on space availability, and instruction varies, from asking the participants to walk at a comfortable pace versus as fast as possible. Therefore, the purpose of this narrative review is to summarize the measurement properties, strengths, and limitations of a fixed-distance walk test ≤ 40 meters in adults with knee OA. Good measurement properties in terms of reliability and validity were observed across the different testing protocols for fixed-distance walk test (i.e., any distance ≤ 40 m and fast- or self-paced). Therefore, clinicians and researchers can select a testing protocol that can safely and consistently be performed over time, as well as provide a practice trial to acclimatize the patients to the fixed-distance walk test.