Hip joint loading during walking in people with hip osteoarthritis: a systematic review and meta-analysis

Abstract

Purpose: Hip osteoarthritis (OA) is a prevalent and costly chronic musculoskeletal condition that often results in pain and physical dysfunction. Evidence-based modifiable treatment targets for hip OA remain somewhat elusive and are largely based on evidence from the knee OA literature. Osteoarthritis is considered, at least in part, a mechanical disease. Preliminary evidence implicates abnormal hip joint loading in the pathogenesis of hip OA. Given that hip joint loading is potentially modifiable, there is a need to synthesise the evidence regarding hip joint loading during walking in individuals with hip OA to inform appropriate treatment targets. This systematic review and meta-analysis investigated hip joint loading during walking in people with hip osteoarthritis (OA). Methods: Five databases were searched up to March 29th, 2017. Studies that measured hip joint moments in the frontal or sagittal plane during walking in people with hip OA and contained either a healthy control group or the unaffected leg for comparison were included. Standardised mean differences (SMD) in measures of sagittal and frontal plane loading were pooled as appropriate, using a random effect approach. Univariate meta-regressions were further performed to explore if study and participant characteristics could explain heterogeneity. Among the variables evaluated as predictors of study heterogeneity were sample size, age, body mass index, sex, and walking speed. A further disease-stage sub-group analysis between studies with participants with end-stage hip OA, defined as awaiting hip replacement, and studies with participants with less severe hip OA (early, mild-to-moderate; not awaiting hip replacement) was performed. Methodological quality was assessed using the Downs and Black checklist. Results: Eleven studies with 1,036 participants were eligible and 10 studies were suitable for meta-analyses. Overall, people with hip OA had lower sagittal (SMD −0.83; 95%CI −0.99, −0.67) and frontal plane loading (SMD −0.70; 95%CI −1.12, −0.12) compared to controls. However, substantial heterogeneity was observed (I2 ≤ 90%). Meta-regression analysis determined no association between the SMD in peak external hip flexion moment with any of the study or participant characteristics investigated. In the frontal plane, the meta-regression analysis found an association between the SMD in peak external hip adduction moment and sample size (unstandardized ß −0.01; 95%CI −0.03, 0.00), such that the difference increased as sample size increased. Results by disease stage suggest that people with less severe hip OA have comparable sagittal (SMD 0.04; 95%CI −0.50, 0.58; I2 = 70%) and frontal (SMD 0.01; 95%CI −0.41, 0.43; I2 = 0%) plane loading compared to controls. People with end-stage hip OA have lower sagittal (SMD −1.04; 95%CI −1.45, −0.64; I2 = 74%) and frontal (SMD −0.67; 95%CI −1.12, −0.12; I2 = 71%) plane loading compared to controls. The methodological quality of the studies was generally moderate (and ranged from 53%–92%), with higher scores indicating better quality. Conclusions: Collective consideration of all studies and findings from the meta-analyses suggests that people with hip OA have lower sagittal and frontal plane hip joint loading compared with healthy controls. However, analysis on a limited number of studies indicates that differences in hip joint loading may be dependent on disease stage. People with end-stage hip OA exhibit lower hip joint loading compared to controls, while those with less severe disease appear to be comparable with controls. These findings may have relevance for management in early stages of the disease pathway.