Ask the Expert: Pain in Hip and Knee Osteoarthritis

KEYWORDS:

• cognitive-behavioral
• exercise
• hip
• knee
• osteoarthritis
• pain management

Jari Arokoski is Adjunct Professor in Physical and Rehabilitation Medicine at the University of Eastern Finland, Kuopio and Consultant at the Department of Physical and Rehabilitation Medicine in Kuopio University Hospital. He received his medical degree from the University of Kuopio in 1990 and completed his specialisation in Physical and Rehabilitation Medicine in 1998 at the University of Kuopio. He finished his PhD thesis titled ‘Altered properties of articular cartilage and subchondral bone after long-term joint loading. An experimental study of young beagles’ in 1996. He became Adjunct Professor (docent) of Physical and Rehabilitation Medicine at the University of Kuopio in 2001. He received his Special Competence in Pain Management in 2001, in Rehabilitation Medicine in 2002, in Insurance Medicine in 2007 and in Medical Education in 2008. He has published over 100 peer-reviewed scientific publications on different aspects of musculoskeletal issues particularly on cartilage structure and function, joint loading, physical function and gait in osteoarthritis and the effects of exercise and rehabilitation in knee and hip osteoarthritis. He is Chairman of the Working group for Current Care Guideline for Treatment of Knee and Hip Osteoarthritis in Finland (Finnish Medical Society Duodecim) and President of Finnish OsteoArthritis Research Society (FOARS).

Q To what extent does pain play a factor in the rehabilitation & treatment of hip and knee osteoarthritis?

Pain is the most common complaint of individuals with osteoarthritis (OA) and is also the usual reason for seeking advice. Effective pain management is of utmost important for patients with hip and knee OA. Because the natural history of OA is still poorly understood and there is currently no cure or treatment proven to slow OA progression, the main goals of OA treatment are the management and alleviation of pain, as well as the maintenance and improvement of functional capacity. The guidelines on hip and knee OA management emphasize the need for individualized multimodal approaches that involve a combination of non-pharmacological, pharmacological and surgical treatment modalities [1–3].

Q What are the predictors of pain in patients with hip & knee osteoarthritis, & what preventative strategies are available to the clinician?

A structure–symptom discordance in OA has been widely noted, and the experience of pain in OA differs between individuals for the same degree of joint pathology [4]. The determinants of pain in OA are believed to involve multiple interactive pathways that are best framed in a biopsychosocial framework [4]. OA pain is a subjective experience, influenced by a number of factors, for example, genetic predisposition, prior experience, current mood, coping strategies and catastrophizing, and the sociocultural environment [5].

Pain in hip and knee OA appears to worsen slowly over the years [6]. Rather few studies have provided prospective evidence on the predictors of pain in patients with hip and knee OA. Our 2-year prospective study revealed that a higher educational level, the absence of knee OA and comorbidities, supervised exercise training and habitual conditioning physical activity predicted a lower presence of pain in patients with hip OA [7]. The radiographic severity of hip OA showed no association with pain or disability in this prospective study. Peters and colleagues demonstrated that cardiovascular problems and general morbidity are associated with a greater deterioration for both hip and knee OA, as is social disadvantage and a higher BMI for knee OA [8].

Factors predicting pain in hip and knee OA are multidimensional, and no single factor has been identified as more significant than others. Earlier cross-sectional and these longitudinal studies emphasize the requirement for not only focusing on disease-specific impairment (e.g., radiological severity of OA), but also taking into account individual background (education), psychological factors, obesity and comorbidities, as well as general support when developing optimal treatment and preventative strategies for hip and knee OA.

Q Some of your work has considered effectiveness and cost consequences of exercise therapy in hip osteoarthritis, in your opinion, how important is exercise in the pain management of patients in this population?

According to evidence-based recommendations for the management of hip OA, exercise is commonly prescribed [1–3]. However, there is currently a lack of unambiguous data to support the putative benefits of land-based exercise programs in relieving pain associated with hip OA [9,10]. No optimal exercise regimen (intensity, frequency and progression) has yet been determined and no clear differences have been detected between different types of exercise programs in hip OA.

However, land-based exercise therapy may confer the slight benefits of improved self-reported physical function in individuals with hip OA [9,10]. Our 2-year randomized study also revealed that participants in the combined exercise and general practitioner care group used less NSAIDs and physiotherapy than the GP care group at some follow-up time points, and the mean costs of physiotherapy (not as part of the intervention) per patient were significantly lower in the combined exercise and GP care group than the GP care group [10]. These results may support the positive effect of exercise on pain in hip OA in the long term. On the other hand, based on the results of the systematic Cochrane review, water-based exercise was found to have a small to moderate effect on function and quality of life and a minor effect on joint pain in patients with hip and/or knee OA [11]. Aquatic exercise might be considered as the first part of a longer exercise program for hip OA patients.

Q What forms of exercise do you think hold the most promise for patients in this population, & what is the current gold standard?

Clinical studies have demonstrated muscle weakness, joint motion restriction and deconditioning in patients with hip OA [12]. Thus, the goal of hip OA treatment with exercise is not only to alleviate joint pain, but also to improve functional status, that is, to maintain or increase joint mobility and muscle strength and improve general physical fitness.

Despite the limited research evidence, in my opinion, general aerobic fitness training is a core recommendation in the non-pharmacological management of patients with hip OA. Exercise can be implemented in a variety of formats. Aerobic exercises may include water-based exercises, walking, cycling, skiing and dancing. In particular, water-based exercises might be less painful compared with land-based training as an initial exercise program, especially for patients who are obese. Of course, the decision should be individualized and based on patient preferences and the ability to perform exercises [1]. General aerobic exercise recommendations for the dosage and progression of exercise in older people and people with chronic disease are also suitable for hip OA patients, for example, aerobic moderate-intensity training for at least 30 min/day, or up to 60 min for greater benefit [9,13]

Every hip OA patient should also be encouraged to undertake regular supervised lower extremity strengthening and flexibility exercises developed for patients with hip OA to enhance the functional capacity and neuromuscular performance [9,10]. The exercise program usually consists of several exercises, including a warm-up session and strengthening and flexibility parts. The recommendations suggest progressive strength training, involving the major lower extremity muscle groups, at least 2 days/week at a moderate to vigorous level of intensity (60–80% of one repetition maximum) for eight to 12 repetitions [9,13].

Q Recently you published on cognitive-behavioral therapy interventions for knee pain in osteoarthritis. What does your, & the research at large, suggest about this type of intervention for osteoarthritic-related pain?

Pain research has revealed the psychological factors (e.g., cognitive, behavioral and emotional) influencing and associated with the treatment, coping and chronicity of people with chronic pain [14]. A growing body of evidence suggests that these factors are also important among people with knee OA. Psychological distress, including depression or a depressed mood, or anxiety has been associated with higher levels of pain in OA patients [15,16]. Moreover, pain catastrophizing [17] and social isolation [16] have predicted higher levels of pain in OA patients, and poor coping strategies [18,19] have predicted higher levels of both pain and dysfunction.

Since psychological factors play a role in the experience of OA pain, interventions targeted at improving them should be investigated. Different behavioral and cognitive-behavioral (CB) treatment modalities have been studied alone and in combination with other interventions in knee OA patients. However, the number of randomized controlled trials (RCTs) so far conducted in this field has been relatively small and the results have been inconsistent [20]. Our randomized cognitive-behavioral therapy intervention study aims to explore the effectiveness of the CB group intervention described by Linton, modified for patients with knee OA [20,21]. The preliminary results will be presented in the near future.

Q How important do you believe a multi-disciplinary approach is in the treatment of pain in this population?

The latest OA treatment recommendations support a patient-centered, combined multidisciplinary approach rather than a discipline-specific approach [1–3]. However, previous RCTs on hip and knee OA treatment have mainly evaluated single types of separate non-pharmacological, pharmacological or surgical treatment modalities. Earlier treatment protocols have also mainly aimed at alleviating symptoms and functional consequences, whereas several other factors, for example, comorbidities, social, psychological and other personal factors, should to be taken into account when developing an individualized treatment plan for hip and knee OA patients.

A multidimensional treatment program with a multidisciplinary team that includes a doctor, physiotherapist, psychologist, nutritionist, social worker and occupational therapists might constitute an appropriate comprehensive treatment program. However, there is currently insufficient evidence regarding the effectiveness of multidimensional interventions for hip and knee OA. I believe that some OA patients with multiple long-term health, social and psychological problems would benefit from this type of treatment approach.

Q What future studies are needed & what areas of intervention do you believe hold the most hope in tackling pain in patients with knee and hip osteoarthritis?

In daily clinical practice, the conservative treatment of hip and knee OA is usually multimodal, combining different nonpharmacological and pharmacological treatment options. However, there is limited evidence supporting this type of global multi-disciplinary rehabilitation approach. The effectiveness and cost consequences of this type of rehabilitation, as well as single types of treatments, should be evaluated in actual OA patients, for example, patients with multiple comorbidities, as well as socioeconomic and psychological problems, in pragmatic randomized controlled trial settings. The factors explaining and predicting the rehabilitation outcomes should also be investigated.

Treatment targeted more specifically at different OA phenotypes, for example post-traumatic, metabolic, ageing, genetic and pain phenotypes, might lead to improved outcomes in the future [22]. Currently, obesity is the only main modifiable biomechanical and systemic risk factor for hip and knee OA [23]. Better insight into how obesity and weight loss affect joint structures would open new opportunities for the prevention and treatment of OA.

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The opinions expressed in this article are those of the interviewee and do not necessarily reflect the views of Future Science Ltd.

Financial & competing interests disclosure

The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.