To our knowledge this is the first randomized clinical trial comparing the effect of a patient specific education program and manual therapy to a minimal intervention consisting of a simple home stretching exercise regimen in patients diagnosed with unilateral hip OA.
Such a trial is warranted because the vast majority of trials in hip OA until now have been dealing with surgery (73%) or pharmacological interventions (20%) in spite of the fact that recent guidelines for the management of this condition recommend a combination of non-pharmacological and pharmacological interventions as first line treatment [4–7].
The relevance of this research is further based on the continuous increase in the number of patients suffering from OA which is anticipated during the coming decades when both life expectancy and the elder population will rise accordingly . With exploding health care costs and maybe even increased mortality for this patient population the evaluation of simple interventions with proven beneficial effect on functional disability, pain and quality of life should be high on the agenda both from an individual and societal perspective [43, 44].
The results so far of the effect of hip school or manual therapy have been based on only a few RCTs [15, 20, 45] or uncontrolled pre-post comparisons [46, 47], and with respect to the direct comparison of manual therapy versus hip school no studies have been performed until now. Our long term interest is in the effect of manual therapy in addition to hip school versus hip school alone, so we included these two groups in our trial. However, for several reasons it is uncertain how well these two therapies will work in our setting: First, the results published so far may reflect publication bias. Second, none of the studies have been performed in Denmark. The hip school does not yet have a tradition in Denmark and manual therapy for hip OA is, to our knowledge, not a common line of intervention. Third, our measurement instruments for success are not identical to those used in the previous studies. Hence we decided to start with a small study assessing the efficacy of the two active treatments. Deciding on a primary outcome in OA research is challenging as it is common for OA patients to rate different domains of the disease experience, e.g. pain and/or reduction in activities of daily living, as their primary complaint. We have decided on pain as the primary outcome which is measured on an eleven-point NRS. At initial contact patients are phoned and asked about possible criteria for exclusion and to avoid a large floor effect on the primary outcome patients are excluded if their pain experience is rated as two or less on the eleven-point NRS.
Strictly speaking the intervention period applies only for the manual therapy and the hip school groups. For the minimal intervention group it is arbitrary because they only receive a one time, five to ten minutes instruction on the exercise program. The purpose of the hip school is to teach the patients an understanding of their condition, to cope with it as well as improve and adapt activities of daily living. This learned effect is of course expected to continue after the intervention period. Any effect of the stretching exercises is expected in all three groups and will not favor any one group over another.
For practical purposes all three groups have a follow-up immediately after the hip school and manual therapy interventions and are then followed at 3 and 12 months to detect changes between groups over time. This does however not reflect common practice as patients with chronic conditions often are followed and treated over months and even years with varying time between consultations depending on symptom severity and flare-ups. Specifically regarding the hip school follow-up sessions would likely encourage modifications of activities of daily living as well as adjustments of exercise regimes. Specifically regarding the manual therapy, it is not uncommon to schedule future consultations for evaluation and treatment if this is perceived beneficial by the chiropractor/therapist and the patient in order to maintain the obtained progress. This practice of follow-up visits is also performed with exercise regimes and patient education programs for reinforcement of confidence and positive behavior as well as adjustments and progression of exercises.
The reasons for inclusion of a control intervention are threefold. First, home programs delivered in the form of a leaflet are often given to this patient group at the time of first diagnosis and our group C thus reflects common practice in many settings. Second, including a control group or minimal intervention group is common in clinical trials that examine the effectiveness of non-pharmacological interventions particularly when long-term follow-up is performed in order to investigate efficiency and cost-effectiveness [48–51]. Third, the effect of a hip school has not previously been compared to a minimal non-pharmacological intervention. It is however possible that patients ending up in the minimal intervention group will feel they are missing out on "treatment" and on their own seek care similar to the hip school or the manual therapy. In order to prevent this, patients in all three groups are encouraged NOT to seek other interventions from baseline to the three months follow-up. This information is provided both in the written material and it is repeated orally at the baseline clinical examination, at randomization and at the 6 weeks clinical examination. Furthermore, patients will be asked specifically at all follow-up points if they have initiated other treatments for their hip condition since the last examination and follow-up.
Any added effect in the group receiving hip school with or without the addition of manual therapy in comparison to the minimal control intervention is of course not necessarily directly linked to the physical component of the interventions. Empathy, social and psychological interactions are important factors in any clinician/therapist patient relationship but the ratio of each to the effect of the physical components is not known. Any measured effect regarding increase in the secondary outcome hip range of motion is however less likely to be influenced by any verbal or empathic contact between patient and clinician/therapist.
The internal validity of the trial is influenced by a positive performance bias by patients participating in the groups receiving hip school with or without the addition of manual therapy whereas patients ending up in the minimal intervention group may experience negative performance bias and feel neglected and not subjected to a "real" treatment. Finally, the list of exclusion criteria may limit the external validity and generalizability, for example, the results may not be directly transferable to patients with hip OA who have a variety of co-morbidities or have hip OA due to moderate or severe hip dysplasia.
Blinding of participants and the providers of the three interventions is another potential problem that may influence the results of the trial. The results from the groups are likely to be influenced by the complex interactions between participants and providers. This includes the verbal communication, physical interaction and empathy between participant and provider. Blinding of the assessor is however possible and this will be done by coding the ID numbers of the participants by a person not involved in the study.
We have designed a study with the main purpose of comparing a patient education program with or without the addition of manual therapy to a minimal intervention in patients with hip OA. The results of this proof of principle study will further inform the design of future RCTs involving non-pharmacological interventions and potentially also the management of patients with early unilateral hip OA.
The results of the study will be submitted to a peer-reviewed journal for publication irrespective of the outcome in accordance with the CONSORT guidelines for reporting of clinical trials .