Hip Osteoarthritis Prognostic Factors and Treatment Effect Modifiers

Research output: ThesisPh.D. thesis


The overall aims of this PhD thesis are to investigate prognostic factors for total joint replacement in hip OA and imaging findings as effect modifiers of non-surgical treatment in knee and hip OA. The thesis includes a systematic literature review on whether imaging findings are modifiers of treatment effect in non-surgical knee and hip OA interventions, a reliability study on diagnostic ultrasound imaging in hip osteoarthritis, and a registry study on prognostic factors for total hip replacement.

The systematic review of subgroup analyses from randomized controlled trials (study I) appraises the literature on diagnostic imaging findings as treatment effect modifiers for non-surgical knee and hip osteoarthritis treatment. The aim was to assess if baseline diagnostic imaging findings on radiographs, CT, MRI, and ultrasound identifies subgroups of patients with knee or hip osteoarthritis who respond better (or less) to various non-surgical interventions. Seven studies investigating treatment effect modifiers in knee or hip osteoarthritis were identified, and only two fulfilled the methodological criteria for subgroup analysis. In one study, participants with moderate to severe radiographic knee OA (Kellgren-Lawrence 3-4) had additional symptomatic benefits of wearing unloading shoes compared to conventional walking shoes compared to those with mild OA (KellgrenLawrence 2), indicating that radiographic severity potentially modifies the effect of unloading shoes in knee osteoarthritis. However, the methodological limitations in the included studies, the limited number of suitable studies, and the heterogeneity between them did not permit conclusions about imaging findings as treatment effect modifiers in people living with knee and hip osteoarthritis. In conclusion, the review identified a knowledge gap and frequently occurring subgroup analysis limitations.

In the reliability study (study II), the objectives were to assess the inter-and intra-rater reliability of ultrasound imaging in patients with hip osteoarthritis between two experienced ultrasound operators and the agreement between findings on ultrasound and radiographs. To our knowledge, this is the first reliability study on hip ultrasound to include differences in the scanning technique between the two operators. The study demonstrated excellent inter-rater reliability of ultrasound findings related to hip effusion/synovitis and substantial to almost perfect inter-rater reliability on the most common ultrasound findings related to hip osteoarthritis. Intra-rater reliability was similar or higher. The agreement between the severity of different radiographic findings and osteoarthritis graded with diagnostic ultrasound and on radiographs using Kellgren-Lawrence grading was fair to moderate, indicating that radiographs and ultrasound scorings only assign similar gradings to some extent. In conclusion, the study supports ultrasound imaging as a reliable tool in assessing hip osteoarthritis. These results form the basis for further research on the prognostic and diagnostic value of ultrasound findings in hip osteoarthritis patients.

The registry study (study III) used data from the ongoing nationwide initiative ‘Good Life with osteoArthritis in Denmark’ (GLA:D®) and national registers. The aim was to describe the total hip replacement rate and prognostic factors for total hip replacement in participants with hip osteoarthritis in a large cohort of patients with hip osteoarthritis. The study is relevant because it provides insight into a population where the evidence on prognostic factors is conflicting. Potential prognostic factors included demographic and disease-specific baseline characteristics and measures of physical activity and quality of life. Within two years, 30% received a total hip replacement. Of 22 baseline candidate prognostic factors, 14 were statistically significant for total hip replacement. The rate of total hip replacement was significantly greater among individuals with higher pain scores, lower hip-related quality of life, better general health, previous total joint replacement in another joint, those wait-listed for total hip replacement, and those with self-reported radiographic osteoarthritis. Interestingly, 40% of those already wait-listed for total hip replacement,when enrolled in the program, had not received a total hip replacement after two years, suggesting that even those eligible for surgery can change the course towards total hip replacement.
Original languageEnglish
Awarding Institution
  • University of Southern Denmark
  • Hartvigsen, Jan, Principal supervisor
  • Skou, Søren Thorgaard, Co-supervisor
  • Arnbak, Bodil Al-Mashhadi, Co-supervisor
  • Fredberg, Ulrich, Co-supervisor
Publication statusPublished - 20. Apr 2022

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