Osteoarthritis (OA) is a frequent chronic musculoskeletal pathology that usually causes great disability and significant healthcare costs. Substantial scientific evidence indicates a role for central sensitization in OA pain. Reconceptualization of pain through Neuroscience Education (NE) is an intervention that has already been used successfully in some chronic musculoskeletal pain conditions characterized by alteration on CNS pain processing or central sensitization (i.e. chronic low back pain, chronic fatigue syndrome, widespread pain and chronic whiplash associate disorders).There is compelling evidence that NE have a positive effect on pain, disability, catastrophization and physical performance for chronic musculoskeletal pain disorders, yet studies examining the value of NE for OA patients are essentially lacking.

The primary aim of this study is to assess the effect of NE on pain, disability and physical performance in subjects with chronic OA knee pain waiting for replacement surgery. This will be the first time NE will be addressed specifically to OA pain. To investigate the benefits of NE on pain related to knee OA, the effect of a manual therapy intervention combined with NE (MT+NE) will be compared with this same manual intervention plus an educational program based on a traditional patho-anatomical or biomedical model (MT+E). The following secondary aims will be addressed as well:

• Examining the effects of the two interventions on the mechanism of central sensitization in patients with knee OA;
• Examining the effects of the two interventions on pain catastrophizing, illness perceptions and kinesiophobia in patients with knee OA;
• Finally, it is aimed at identifying effect moderators for NE in patients with knee OA.

Osteoarthritis (OA) is a frequent chronic musculoskeletal pathology that usually causes great disability and significant healthcare costs. Substantial scientific evidence indicates a role for central sensitization in OA pain. Pathophysiological mechanisms underlying central sensitisation are complex and numerous, but the net effect is an amplification of neural signaling within the CNS than elicits pain hypersensitivity. Central sensitization management is an area of great interest at least in a subgroup of patients with OA pain.

Reconceptualization of pain through Neuroscience Education (NE) is an intervention that has already been used successfully in some chronic musculoskeletal pain conditions characterized by alteration on CNS pain processing or central sensitization (i.e. chronic low back pain, chronic fatigue syndrome, widespread pain and chronic whiplash associate disorders). Moreover, some clinical guides to help clinicians to identify and explain central sensitization through NE, have been recently published. However, this kind of intervention has never been tested specifically for chronic pain related to OA.

Preoperative education centered on a biomedical model of anatomy and pathoanatomy as well as procedural information has limited effect in reducing postoperative pain after total hip arthroplasty and total hip arthroplasty surgeries. Preoperative educational sessions that aim to increase patient knowledge of pain science (i.e. NE) may be more effective in managing postoperative pain. NE is a cognitive-based educational intervention that aims to reduce pain and disability by helping patients gain an increased understanding of the biological processes underpinning their pain state. There is compelling evidence that NE have a positive effect on pain, disability, catastrophization and physical performance for chronic musculoskeletal pain disorders, yet studies examining the value of NE for OA patients are essentially lacking.

Joint mobilization has been shown to be a useful modality to reduce pain related to osteoarthritis. Regarding the knee joint, two recent systematic reviews demonstrated the usefulness of manual therapy and exercise for the management of knee OA. Moreover, Deyle et al reported a preliminary clinical prediction rule which may help to identify the minority of knee OA patients who are unlikely to respond to this management approach.

The primary aim of this study is therefore to assess the effect of NE on pain, disability and physical performance in subjects with chronic OA knee pain waiting for replacement surgery. This will be the first time NE will be addressed specifically to OA pain. To investigate the benefits of NE on pain related to knee OA, the effect of a manual therapy intervention combined with NE (MT+NE) will be compared with this same manual intervention plus an educational program based on a traditional patho-anatomical or biomedical model (MT+E). The following secondary aims will be addressed as well:

• Examining the effects of the two interventions on the mechanism of central sensitization in patients with knee OA;
• Examining the effects of the two interventions on pain catastrophizing, illness perceptions and kinesiophobia in patients with knee OA;
• Finally, it is aimed at identifying effect moderators for NE in patients with knee OA.

Inclusion Criteria:

1. An established diagnosis of knee OA according to American College of Rheumatology criteria and Kellgreen/Lawrence scale grades.
2. To be in a waiting list and scheduled to undergo primary knee arthroplasty.
3. To have sufficient Spanish language skills to comprehend all explanations and to complete the assessment tools.

Exclusion Criteria:

1. Previous knee joint replacement surgery of the affected joint or any other lower limb surgery within the past 6 months.
2. Stated inability to attend or complete the proposed course of intervention and follow-up schedule.
3. Presence of co-morbidities associated with cognitive impairment.
4. Co-existing inflammatory, metabolic, neurological or severe medical conditions, defined as a diagnosis in the medical record severe enough that the patient cannot participate fully in the study procedures (i.e. cardiovascular disease).
5. Functional illiteracy.