Brain-targeted treatment in people with painful knee osteoarthritis in tertiary care: was it feasible?

Knee osteoarthritis (OA) is a complex disorder that commonly results in diminished physical function, poor quality of life, and reduced life expectancy [1]. While several treatments such as exercise therapy [2] (Pilates, strength, flexibility, conditioning training) have been effective at reducing pain in people with knee OA, unfortunately, the results are often short-lived.

The present study [3] aimed to pilot a new treatment called brain-targeted treatment (BT) for knee OA that targets the way the painful knee is represented in the brain (i.e., the sensory representation for the knee). This was based on recent findings demonstrating that people with knee OA have alterations to their sensory representation [4,5]. Previous studies in other painful conditions (i.e., phantom limb pain or complex regional pain syndrome) have demonstrated that targeting these representations can reduce pain and disability [6-7]. Thus, the aim of the study was to evaluate whether BT was feasible and had clinical impact (i.e., reduced pain and improved function) in people with knee OA, when implemented in a tertiary care setting.

Ten participants with knee OA were recruited. The study involved 3 phases: (a) no treatment control phase; (b) BT; and (c) usual care. Each phase lasted 2 weeks. All participants completed a baseline assessment which was followed by the no treatment control phase. Participants then undertook a second assessment and were randomly allocated to an intervention group (BT or usual care). Participants then underwent a third assessment and the alternate treatment (usual care or BT). The fourth and final assessment was made on completion of the second treatment.

Brain-targeted Treatment (BT) included:

  1. Left/right foot judgment training: Participants were required to spend 5 minutes every hour identifying whether a series of images (30 images) of feet or lower limbs belonged to the left side or the right side of the body.
  2. Touch discrimination training (TDT): For 15 minutes twice a day, participants were required to identify the location of a stimulus that was delivered to their affected knee (without viewing the knee) by a trained second person/helper, and indicate whether the stimulus was sharp or blunt.

Usual conservative care included strength and flexibility training, including passive knee joint mobilization [4].

Feasibility outcomes were timely recruitment, intervention completion, treatment compliance (time, and availability of helper), follow-up rates, pain and functional impact of treatment.  In addition, fear avoidance beliefs, left/right judgment performance and two-point discrimination threshold were assessed.

The study found that BT in a tertiary care setting was not feasible and that changes would need to be made before considering a larger trial. Recruitment was difficult with only 5% of all assessed patients eligible to participate (19/355), with most ineligible due to lack of translation services for non-English speakers. Eleven of the 19 eligible subjects agreed to participate and a further 1 participant was excluded due to a diagnosed neurological disorder. Treatment compliance for the touch discrimination portion of BT was poor, however intervention completion and follow-up rates were both excellent, suggesting that the study processes worked well. Last, there was no effect of these short interventions on pain or function, although both treatments reduced fear avoidance beliefs, improved left/right judgment performance and reduced two-point discrimination threshold.

Despite some interesting clinical findings this study had some significant limitations. They reported that they were unable to access interpreters which impacted on recruitment and also meant that they missed out on a large demographic of patients in a tertiary care sitting.

Treatment compliance was also low, most likely due to the low willingness/availability of helper in TDT. The authors concluded that a system that eliminates the second-person dependency barrier might be helpful.

Indeed, one possibility could be to use mobile devices such as laptops, personal digital assistants, or mobile phones, to run a program which is delivered to the patient via skin contact (e.g., with a tensor sleeve on the area with embedded sensors).  For example, using an iPhone/iPad app to run tactile stimulation may be applicable and would certainly decrease the need for a helper. Given that effects of tactile discrimination are only seen when the patients actively discriminates location [7], it would be imperative that such a system allows patients to respond in real-time to the tactile stimuli via the installed app and receive feedback about whether they have correctly responded. However, regardless of the use of such technology, physiotherapists should take into account the patients’ lifestyle when recommending any intervention. Tailoring an intervention plan to every patient based on his/her unique time barriers and interests can be helpful to promote treatment compliance. It is interesting to consider whether creating TDT into an app based game (where you can compete against yourself or others) might help to increase interest in the face of ever-present time barriers.

About Pouya Rabiei

Pouya has a Masters in sports injury from the school of sports science, Azad University, Iran. His research interests are the prevention of musculoskeletal injuries especially in athletes, understanding of brain function and its relation with biomechanics in patients with spinal pain, and the effect of movement-based interventions combined with psychological ones for LBP.

References

[1] Palmer KT. The older worker with osteoarthritis of the knee. British medical bulletin. 2012;102:79-88.

[2] Mazloum V, Rabiei P, Rahnama N, Sabzehparvar E. The comparison of the effectiveness of conventional therapeutic exercises and Pilates on pain and function in patients with knee osteoarthritis. Complement Ther Clin Pract. 2018;31:343-8.

[3] Harms A, Heredia-Rizo AM, Moseley GL, Hau R, Stanton TR. A feasibility study of brain-targeted treatment for people with painful knee osteoarthritis in tertiary care. Physiother Theory Pract. 2018:1-5.

[4] Stanton TR, Lin CW, Smeets RJ, Taylor D, Law R, Lorimer Moseley G. Spatially defined disruption of motor imagery performance in people with osteoarthritis. Rheumatology. 2012;51:1455-64.

[5] Stanton TR, Lin CW, Bray H, Smeets RJ, Taylor D, Law RY, Moseley GL. Tactile acuity is disrupted in osteoarthritis but is unrelated to disruptions in motor imagery performance. Rheumatology. 2013;52:1509-19.

[6] Moseley GL. Graded motor imagery for pathologic pain: a randomized controlled trial. Neurology. 2006;67:2129-34.

[7] Moseley GL, Zalucki NM, Wiech K. Tactile discrimination, but not tactile stimulation alone, reduces chronic limb pain. Pain. 2008;137:600-8.