Hip symptoms contribute to low back pain-related disability in older adults with a primary complaint of low back pain: the Delaware spine studies

Abstract

Purpose: Low back pain (LBP) is the most frequently reported musculoskeletal problem among older adults. Clinicians specializing in the care of musculoskeletal conditions have often proposed a link between hip dysfunction and LBP among older adults. Offierski and McNab originally described hip-spine syndrome as the presence of symptoms due to an abnormal biomechanical relationship between the hip joint and spine likely related to degenerative pathology in one or both joints; but, little work has been done to elucidate this relationship. The purpose of this study was to determine the prevalence of clinical hip symptoms, which are indicative of hip osteoarthritis (OA), among older adults with a primary complaint of low back pain, and determine whether these hip symptoms contribute to LBP severity and LBP-related disability. Methods: We have conducted an analysis of baseline data from the Delaware Spine Studies cohort study of 228 older adults with a primary complaint of LBP that is greater than any other musculoskeletal pain complaint (mean age: 69.75+/−6.85 years). We examined clinical hip symptoms that were proposed predictors of radiographic hip OA according to American College of Rheumatology (ACR) guidelines by Altman et al, including hip joint pain, morning stiffness in the hip that lasts less than 60 minutes and pain with hip internal rotation (IR). We assessed movement-evoked pain in the lower back during the six minute walk test (6 MW) using a numeric pain rating (0–10). We also assessed LBP-related disability using the Quebec Low Back Pain Disability Scale (0–100). For both outcomes, higher scores indicate worse status. Descriptive statistics were used to estimate the prevalence of the hip symptoms. Analysis of covariance (ANCOVA) was used to determine the association between presence of each individual hip symptom and our outcomes of interest, movement-evoked LBP and LBP-related disability. ANCOVA was also used to explore the cumulative contribution of hip symptoms (presence of 0, 1 or 2+ hip symptoms) to LBP and disability. ANCOVA models were adjusted for age and sex. Results: Hip joint pain (66.2%), morning stiffness (58.8%) and pain with hip IR (18.9%) were fairly common among our sample of older adults with LBP. In fact, 72.8% of all participants with LBP had at least one hip symptom. Of the 228 participants with LBP, 62 (27.2%) had no hip symptoms, 66 (28.9%) had one symptom and 100 (43.8%) had 2 or more symptoms. Presence of either hip joint pain or painful hip internal rotation alone were associated with greater LBP-related disability (p&lt.015), but only hip joint pain was associated with greater pain severity (p = .034). Morning stiffness in the hip alone was not associated with either elevated pain or disability (p&gt.05). Among these older adults with LBP, presence of 2 or more hip symptoms was associated with greater pain severity (+1.07 points, 95%CI: .14, 2.01, p = .019) and LBP-related disability (+10.63 points, 95%CI: 3.97, 17.29, p&lt.0001) as compared to absence of hip symptoms. Conclusions: Hip symptoms are prevalent among older adults with a predominant complaint of LBP and are associated with greater movement-evoked pain severity and LBP-related disability. There has long been consensus that researchers should focus on classifying patients into clinically relevant subgroups that share similar clinical characteristics to improve treatment outcomes. It appears that one such subgroup among older adults with LBP consists of those with co-existing hip symptoms. Our data suggests that the relationship between LBP and co-existing hip symptoms should be systematically studied in a longitudinal fashion to determine if hip joint dysfunction should be a potential treatment target for a subgroup of older adults with LBP.