The HIP Self-management Study

Background:

Continuous or intermittent lateral hip pain, also known as greater trochanteric pain syndrome (GTPS), is a common chronic and disabling musculoskeletal condition. It usually occurs during the fourth to sixth decades of life, predominantly among women. The prevalence and incidence rates have been reported to be 4.2 and 3.3 per 1000 person-years, respectively, in the general practice population. The impact of GTPS is reported to be debilitation, as it typically disturbs sleep and limits daily function and participation in work.

Exercise and education are considered the cornerstone of treatment, and in recent randomized controlled trials this combination has demonstrated significant improvements in pain and function. However, studies have failed to show any difference between specific hip exercises and non-specific (sham) exercises in combination with patient education. As GTPS is recurrent and persistent of nature, person-centered care and the incorporation of self-management strategies could be beneficial. To the investigators knowledge, this study will be the first one to investigate self-management for the current patient population. Results from the study may change the type, delivery, and content of treatment for patients with GTPS, relevant for both primary- and secondary care.

The main objective of the study is to evaluate the clinical effectiveness of a self-management program compared to usual care for patients with GTPS.

Methods and analyses:

110 patients will be recruited and randomly allocated into one of two groups: 1) self-management or 2) usual care. The randomization sequence will be computer-generated with blocks of various size, unknown to any of the research team. Due to the nature of therapeutic studies, blinding of the participants and the treating physiotherapist is not possible. The investigator assessing the outcome measures will be blinded to group allocation.

Descriptive statistics will be collected at baseline, and presented as means with standard deviation (SD) or as medians with inter quartile range (IQR). The primary analysis will be conducted on the intention to treat population and compare the two intervention groups (self-management vs usual care) on mean difference in pain and disability (VISA-G-N score) at baseline, 3 and 6 months. The estimated mean difference between groups at 6 months (main endpoint) will be analyzed using a longitudinal mixed effects model analysis of covariance. Baseline score on VISA-G-N, time, intervention and interaction between time and intervention will be included as covariates. Secondary outcomes assessed at multiple time points (baseline, 3, 6 and 12 months) will be analyzed by the same approach as described for the primary outcome, on both the intention to treat population and the per protocol population.

The degree of missingness will be explored using sensitivity analysis with multiple imputation and/or the use of an alternative repeated measures mixed model analysis accordingly, to assess the robustness of data. In addition, multivariable logistic and linear regression analysis will be used to explore predictive factors, such as demographics, expectations, clinical findings, and psychosocial factors for primary and secondary outcomes. Model building will be done in a way that is appropriate for the given sample sizes, by restricting the number of potential predictive factors and considering shrinkage methods to stabilize predictions. Mediation analysis will be performed to explore the causal pathway between treatment allocation and the primary outcome of pain and disability by considering, amongst others, pain self-efficacy and emotional distress as potential mediators that may be part of the causal pathway between intervention and outcome.

Inclusion criteria

• Participants between 18 and 70 years of age
• History of lateral hip pain > 3 months
• Reported average pain intensity the last week ≥ 3 on a numeric rating scale
• Lateral hip pain is the main complaint
• Pain on palpation of the greater trochanter region
• In addition, lateral hip pain on at least one of the following tests:

• Single leg stance test: standing 30 seconds on the affected leg
• FADER: passive stretch/compression of gluteus medius/minimus
• FADER-R: static muscle test with resistance to internal hip rotation
• ADD: passive stretch to hip adduction in sidelying
• ADD-R: resisted hip abduction in sidelying
• FABER (Patrick's) test

A positive test is defined as a spontaneous reproduction of the participant's lateral hip pain. In participants with bilateral lateral hip pain, the worst hip will be included, and the presence of bilateral pain will be documented.

Exclusion criteria

• Significant back pain causing referred pain to the lateral hip
• Clinical signs of radiculopathy
• Symptomatic osteoarthritis
• Other hip joint pathologies
• History of trauma or surgery on the affected side
• Pregnancy or post-partum pelvic pain (under 12 months since birth)
• Active cancer
• Not able to write, read, and comprehend Norwegian (without the use of an interpreter)