Process of change for people with knee osteoarthritis undergoing cognitive functional therapy: a replicated single-case experimental design study

Figures & data

Figure 1. Schematic representation of the study design and procedures. Footnote to Figure 1. Short questionnaire measured the following items: patient-specific function, pain intensity, and psychological factors (bothersomeness, fear beliefs, knee confidence, pain control and pain catastrophising). Long questionnaires measured the following items: disability and pain (Knee injury and Osteoarthritis Outcome Scale using the daily living and pain sub-scales), and psychological factors including, fear beliefs (Knee Osteoarthritis Fears and Beliefs Questionnaire), Pain control (Brief Pain Coping Inventory-2), and Pain catastrophising (pain catastrophising scale). Functional tests included: 40m fast-paced walk test (Wright et al 2011), and a 30 second chair stand test (Jones et al 1999). Both functional tests are OARSI guideline recommended (Dobson et al 2013).

Table 1. Multidimensional factors and cognitive functional therapy (CFT) management for the four clinical cases.

Examination findings	Case 1	Case 2	Case 3	Case 4
Interview
History	60-Year-old female, property manager and cleaner developed right antero-lateral knee pain insidiously over the last 3 years. She continued to work and be active but the pain started interfering with daily activities. Progressively reported worsening of function. She was scanned and told by a Surgeon that she had degeneration in her knee and would need a total knee replacement in the near future. She had undergone massage, knee and hip strengthening exercises, orthotics, pain medication, and a hyaluronic acid injection, without long term benefits. She had no long-term self-management plan.	50-Year-old male, manual worker with right knee pain for the last 30 years, and worsening symptoms over the last 10 years. At age 16, injured his knee playing football and had a meniscectomy and several subsequent arthroscopic ‘clean ups’ with short-term benefit, but progressive functional deterioration. He was scanned and told by the surgeon that he had the “knee of a 65-year-old” and that a knee replacement is warranted. Rehabilitation over the years has included gym exercises, but it has been inconsistent. Currently, he has no active management plan. His pain condition is worsening in severity over the past 12 months.	73-Year-old male, farmer with bilateral knee pain worsening over the last four years. Significant illness 4 years ago. Currently impacting on working on the farm climbing silos, getting in and out of the truck, carrying, etc. He had several arthroscopic ‘clean ups’ and bilateral lateral release surgery followed by rehabilitation with limited success. Stopped playing tennis which he described ‘kept him fit and in touch with friends’. Orthopedic surgeon reviewed latest scans and said that a total knee replacement is inevitable. However, he should try to hold off due to medical history including bowel cancer and recent infection. Condition worsening. He has no current rehabilitation plan.	66-Year-old female, business manager with life-long history of right knee pain. Pain gradually worsened over the last 15 years, impacting on her ability to walk long distances, play tennis, deal with stairs, and get up from sitting. Has seen several GPs and physiotherapists. Tried different exercise programs, including Pilates, GLA:D and an individualized gym program with limited success. Orthopedic surgeon said the cause of the pain was cartilage degeneration due to having bowed legs, and recommended knee replacement surgery. Currently attending rehabilitation class but not noticing any improvement.
Patho-anatomical factors	Grade 1 Kellgren-Lawrence score on X-ray and MRI.	Grade 2 Kellgren-Lawrence score on X-ray and MRI.	Grade 3 Kellgren-Lawrence score on X-ray and MRI.	Grade 3 Kellgren-Lawrence score on X-ray and MRI.
Pain characteristics	Antero-lateral knee (patellofemoral joint) pain with loading activities such as during sit to standing, stepping up, and stepping down.	Postero-medial knee pain along the tibiofemoral joint with knee flexion such as sitting and kneeling, and with load in flexion such as climbing up and down ladders.	Antero-lateral knee pain along the tibiofemoral joint with walking, squatting, knee flexion climbing stairs, and lateral movements or changing directions.	Antero-medial knee pain along the tibiofemoral and patellofemoral joints on palpation, and with activities such as walking, stepping down, and getting up and down from sitting.
Psychological factors: Cognitive	Beliefs – knee pain during activities was causing more damage to her knee. Low pain self-efficacy. Avoidant coping style relating to loading, and physical activities.	Beliefs – “I’m old and I used my knees too much…this (pain) is wear and tear…not much space in there”. Very careful with knee	Beliefs – pain related to damage in knee joints due to repetitive loading; not much can be done about it. Worried about causing more damage – protective of the knee, avoidant of painful activities.	Beliefs – pain related to wear and tear of the cartilage due to having bowed legs. Worried about further damage and the potential need for knee replacement surgery. Very protective of the knee.
Emotional	Fear of movement and loading Fear about her capacity in the future Keen to “try and get another 10yrs out of the knee”	High pain-related anxiety Low mood due to pain Fear of movement and loading Hopeful about the future, but unsure on what to do	Fear of movement and loading Fear about future and overall health Worried that mother had knee issues	Fear of movement and loading Fear about future and need for surgery High social stress
Social factors	Working Good social support. Physically demanding job	Self-employed – work is biggest worry Impacting on interaction with family Little social support Significant ongoing stressors (work; home)	High social stress Significant ongoing stressors Misses socializing through tennis	High social stress. Positive social interactions in exercise class
Lifestyle factors	Active but has progressively been avoiding exercise and stopped playing squash, and horse riding due to pain, but she was still able to ski.	Walks the dog daily (20–30 min) Inconsistent with the gym Weight loss due to stress last year Poor sleep Work is physically demanding	Work is physically demanding Poor sleep – averages 5–6h/night (diagnosed with obstructive sleep apnoea – wears air pressure machine)	Reduced physical activity significantly (walking and tennis) High demands at work and home Little time for herself Moving less and less
Health related factors	Good overall health Within normal weight range	Poor mental health affected by pain and stress overweight	Poor mental health affected by own health and family stress Within normal weight range	High stress Slightly above normal weight
Physical examination
Sensory profile	Localized hyperalgesia over the lateral aspect of the patellofemoral joint and lateral knee soft tissue with light palpation. Pain increases with knee loading.	Localized hyperalgesia over the postero-medial aspect of the tibiofemoral joint. Pain increases with knee flexion. No pain with loading, unless flexion loading.	Localized hyperalgesia over the antero-lateral aspect of the tibiofemoral and patellofemoral joints. Pain increases with knee loading.	Localized hyperalgesia over the antero-medial aspect of the tibiofemoral and joints. Thigh muscles – tense and sensitive on palpation. Pain increases with knee loading.
Observation of pain provocative functional behaviours	Pain reported during sit to stand and stepping up and down. Sit to stand: Tendency to avoid right leg loading during load transfer. Internal hip rotation of right hip was also noted. Stepping up and down: Upright trunk posture, tensing quadriceps muscle and stiffening knee was noted.	Keeps right leg straight in sitting; puts right leg forward and loads the left leg when getting up from sitting to standing (avoidance of R leg loading). Guarded during active knee flexion (limited to 80 degrees of flexion with report of pain), braces quadriceps and breath-holds. Avoidance of right leg loading during standing. Loss of knee flexion during step down, guarding the knee, hurrying the movement and reluctant to load it during stepping up and stepping down.	Keeps feet tucked under the chair in sitting Use hands to stand up from sitting Braces and breath-holds when loading the knee; moves slowly Weakness and pain pushing off on lateral movement and tennis specific movements	Use hands to get up from sitting; narrow base, breath-holding – slow, stiff and painful. Braced into extension in standing and walking – stiff, unsteady, slow with report of knee pain. Walking with a narrow base and minimal push off, keeping ankles ‘locked’ in neutral (stiff legs). Avoidance of right leg loading during stepping down.
Guided behavioural experiments	Sit to stand: forward bend of the trunk, aligning knee over foot and equalising weight though both legs reduced pain. Stepping up and down: Forward bend of the trunk with a focus on driving power into the foot with a relaxed knee and knee alignment over foot reduced pain. Repetition of these tasks with reduced pain allowed the physiotherapist to guide the patient to reflect on the experience where relaxing and loading the knee provided pain relief – and protecting and avoiding leg loading increased knee pain.	Active knee flexion with focus on engaging hamstrings while relaxing of the quadriceps resulted in reduced the knee pain and increased flexion. Sit to standing with knee flexion and loading of both legs did not increase his pain. Although the knee was pain sensitive during repetitive sit to standing, it did not result in an increase in knee pain. Repetition of knee flexion and loading resulted in greater movement without an increase in pain disconfirming the belief that bending and loading is harmful.	Relaxation of the trunk and diaphragm breathing while getting up from sitting – encouraged to use a wide stance and push through legs to get up (instead of trunk and arms) – led to improved ease of movement and reduced intensity of pain. Side stepping keeping body relaxed, diaphragm breathing, and pushing through the legs to move was less painful and more mobile. Repetition of these tasks increased his confidence and challenged his beliefs that loading equals damage and pain.	Breathing and relaxation of thigh muscles before getting up from chair, leaning body forward and transferring weight to centre of feet; wide base and pushing through the feet to stand up led to pain reduction and increased speed. Walking with a wider base, relaxing the ankles and engaging feet during push off led to less discomfort and ease of walking. Engaging foot when stepping down led to increased confidence and reduced discomfort. Repetition of these tasks increased her confidence and challenged her belief that protection was necessary.
Conditioning	Repeated loading during sit to stand – and stepping resulted in fatigue of the leg muscles.	Deconditioning of hamstrings and hip extensors.	Deconditioning of quadriceps, hamstrings and calf muscles.	Weak calf muscles (soleus). General deconditioning.
CFT intervention	Case 1 6 sessions over 3 months	Case 2 6 sessions over 3 months	Case 3 8 sessions over 3 months	Case 4 8 sessions over 3 months
Making sense of pain Education focused on reconceptualising pain within a biopsychosocial context related to the person’s story. This process addressed any misconceptions about knee osteoarthritis the participant held (e.g., about the role of radiological imaging, the meaning of pain, activity avoidance and movement). Participants were guided to reflect on new ways to conceptualise their condition, behavioural responses to it and their lifestyle, in order to reach their functional goals and improve their knee and general health.	Explain how negative beliefs, fear of movement, activity avoidance and protective muscle guarding sets up a vicious cycle of pain sensitivity and loss of functional capacity. Behavioural experiments disconfirmed the belief that pain equals harm, and led to an experience that that loading her knee is safe. Reinforce that her knee health is optimised by a positive mindset towards her knee, engaging in regular, graduated and confident movement and loading of the knee. Also educate that her pain originates from the patella-femoral joint and not the tibiofemoral joint. Goals – achieve pain control during functional tasks, return to physical activity including horse riding and potentially squash.	Explain that knee replacement surgery is good for knees that can’t sustain load, not for knees that can’t bend. Avoidance of bending and loading the knee is unhealthy for it and keeps it sensitive. Explain how stress, poor sleep, increased body weight, high physical demands and low physical capacity can interplay and lead to joint sensitivity. The loss of knee flexion is associated with quadriceps guarding and weakness/inhibition of the hamstrings. Behavioural experiments disconfirmed the belief that protecting the knee is helpful, and confirmed that the muscles that bend the knee are inhibited, but once engaged he can bend the knee more. Goals – return to normality and do things without having to worry, including playing with the kids, getting in and out of the car, kneeling and climb ladders.	Explain how his activity levels and lifestyle significantly changed after his illness leading to a loss of muscle strength and likely contributing to joint sensitivity. The adoption of movement habits to protect the knee is not helpful and makes the knee sore and less healthy, setting up a vicious cycle of disuse, protection and tissue sensitivity. In addition, the social stressors and poor sleep may contribute as pro-inflammatory factors and further sensitise the knee joint. Behavioural experiments challenged his belief that loading the knee causes damage and pain, building his confidence to use the knee more. Reassurance that despite the changes seen on the scan, the sensitivity of his knees is also influenced by other factors such as muscle weakness, protective guarding, stress and sleep that are modifiable. Goals – reduce pain to work without worrying about his knee; return to playing tennis (singles).	Explain that the adoption of protective habits such as avoidance of movement, activity and stiffening of the knee and ankle increased knee load, contribute to a vicious cycle of disuse, protection and tissue sensitivity. It was also discussed that her activity levels have reduced over the last couple of years due to husband’s health and how this impacted on her conditioning, confidence, and tissue sensitivity. Behavioural experiments disconfirmed the belief that protecting the knee is helpful, and provided confidence to engage her knee and leg in a more relaxed manner during walking, sit to standing and stepping down. It was also discussed how stress and body weight can influence tissue sensitivity, and the importance of regular physical activity on her overall health and well-being. Goals – reduce pain, avoid surgery, and stay active (gym, play tennis, walk).
Exposure with ‘control’ Guided behavioural experiments aimed to promote pain controllability, and confidence, by discouraging unhelpful protective behaviours (e.g., reducing protective guarding through body relaxation) while engaging in provocative, feared or avoided functional tasks. Discrepancies between pain expectations and actual pain experiences were addressed, providing experiential learning opportunities. Newly learnt movement behaviours were then incorporated into valued daily tasks in a graduated manner, while respecting the person’s level of pain and distress. Strengthening and conditioning exercises were introduced according to participant’s presentation and goals.	Sit-to-standing, stepping up, and stepping down with a focus on adopting a relaxed trunk and forward lean posture while driving the movement from her feet. Visual feedback with mirror, video and written instruction. Integrate new strategies into daily life. Graduated conditioning with graded progressions towards sustained and repeated squats, forward trunk lean – focus on engaging the hip and foot while loading both legs equally.	Replace guarding of knee flexion by engagement of knee flexion (hamstring) muscles. Sit with both knees flexed. Sit-to-stand with equal knee flexion and loading Squatting with equal weight to facilitate eccentric lengthen of his quadriceps. Graduated targeted exercises to retrain knee flexors. Stairs training, taking weight through the leg with knee flexion, relaxed and controlled (not hurrying). Encouraged to integrate new movement strategies at work and at home, including kneeling and stepping up and down a ladder.	Replace guarding of the knee and avoidance of pushing through the legs, by relaxing the body and engaging the legs through graded movement and loading of the knee. Sitting with knees relaxed. Sit-to-stand keeping the trunk and arms relaxed, and loading both legs equally. Graded exposure to leg loading. Graduated exercises to target conditioning quadriceps, hamstrings and calf muscles (e.g., squats, steps, ½ lunges). Progress program towards tennis-specific exercises and practice. i.e., Side-side step movements keeping the trunk and arms relaxed, and engaging the legs (mimic tennis).	Replace knee protection with relaxation of thigh muscles and engagement of knee and foot. Sit to stand with wide base, relaxing body forward, no hand support, and engaging the feet and legs to stand up. Walking at a faster and more relaxed pace, wider base, and engaging foot and ankle to move forward Taking weight into leg and controlling own weight with foot when stepping down. Graded exposure to leg loading. General and targeted conditioning of the lower leg and feet muscles
Lifestyle change Participants were encouraged to perform physical activity based on their goals, preference, and accessibility, if they were not doing so. Physical activity was gradually increased in a time-contingent manner. For instance, if the participant’s goal was to be able to walk for 60 min daily, this activity was introduced at the level of their ability and progressed on a time-contingent fashion (e.g., increase of 10% or initially progressing frequency, then time). While engaging in physical activity, emphasis was placed on relaxed, confident movement. Where a person reported high level of stress or poor sleep, relaxation techniques and healthy sleep habits were taught.	Physical activity – daily walking program progressed to gym based on person’s preference.	Physical activity – continue with walking; added graduated stationary cycling to train knee flexion. Weight loss – importance of healthy diet, good sleep habits, and consistent exercise to reduce body weight and decrease inflammatory load on knee.	Physical activity – encouraged to continue being active, and to relax and carry on in the presence of pain (rather than worry, protect and rest until pain subsides). Based on preference – bike, walk, tennis. Sleep – aim for regular sleep routine	Physical activity – encouraged to make time for herself to exercise daily. Encouraged to exercise every day for at least 30 min. Weight loss – importance of healthy diet, and regular exercise to reduce body weight, manage stress, and decrease inflammatory load on knee.

Table 2. Process of change for each participant.

	Phase A	Phase B		Phase A′
Case 1	Pre-intervention	Early-intervention	Post-intervention	Follow up
Understanding of pain (cause)	Biomedical conceptualisation of the cause of her pain “… I’ve been told by the doctors that there’s no cartilage and the bones are rubbing.”	An alternative understanding of the cause of her pain “… I need to exercise to use my muscles properly and get my knee mobile without surgery and less pain.”	A shift in her conceptualisation about osteoarthritis “… the pain is less, definitely… it must be the way I use it, and how much I use it … I’ve realized the value of getting strong and active without fear. Understanding it was healthy to use my knee was key”
Pain control	No control over pain, and avoidance was the only strategy to manage symptoms “… oh no, no I can’t control it. I can’t stop the pain from coming unless I stopped the work. Or stopped the exercising or whatever I’m doing with my knee.”	A new and helpful way of using her knee “… different to what I thought, using my knee is actually helpful.”	Pain control through active engagement. “… just being able to use the leg a lot more confidently and with less pain. I can do leg exercises now which is great”
Behavioural response	Exercise was ineffective. “I tried exercising but it hurt my knee more…. resting also doesn’t work……I’m just trying to think what else could deteriorate your bones so quickly you know? Apart from old age!… … sometimes my knee will lock up and I don’t trust it walking downstairs.”	Exercise may be helpful. “… the exercises, are all to strengthen glute muscles and to teach me to use my knee differently…and it helps.”	Exercising confidently to keep joint healthy. “It (this program) definitely made a difference that’s for sure… so I don’t feel like I need to go and have surgery now …just keep working at the exercises, you know. But confident.”
Emotional response	Low knee confidence and worried about causing damage. “I’m lacking confidence… and I worry about the pain and damage that (using the knee) it’ll cause because it does, it swells up.”	Hopeful about the approach. “… it’s quite exciting to think there is maybe another way…to get my knee better without surgery and less pain. That gives me hope”	Improved knee confidence and reduced worry “I’m able to use it a lot more and I don’t worry about it – I don’t feel so frightened about using it… it feels stronger so I’m more confident. It’s great, and I don’t feel that I need surgery or anything at this stage.”
Case 2	Pre-intervention	Early-intervention	Post-intervention	Follow up
Understanding of pain (Cause)	Pain caused by a worn-out knee that is bone on bone.. “…on the scan, it was just basically bone on bone sort of thing, you know, there was no sort of gap there where cartilage should be…”	Pain due to damage and the way he uses his knee.. “(…) it’s not being used properly you know like my muscles and stuff around it … I am not bending the knee like I should.”	Pain influenced by damage and behaviour. “… you go and see the specialist and he just basically said after you seen the x-ray, you can see how degenerated it was I suppose and that’s where I thought the pain was just from that … but obviously, the pain is also from me not using it correctly. The damage is done, but I’m finding that there’s things that can be done to help… it won’t fix the inside of the knee though.”
Pain control	Avoidance of painful or potentially damaging activities. “I try and watch what I’m doing a lot… if I can avoid getting up on the ladder or something I will. I may take some painkillers, but generally I just try and rest it up.”	Changing the way in which he uses the knee may help. “… the [physiotherapist] just went over a lot more things and just made a lot of sense of what’s wrong with me and what I need to do to make things a bit better….so, I’ll try to change some bad habits and use this leg a bit more now.”	Engaging with knee in a new way has been helpful. “Mostly it’s not hurting now so, I gotta continue to do that and eventually I will be able to bend it more and then I won’t have any pain at all…but kneeling is still sore…the inside is still damaged – hopefully this program will still help it.”
Behavioural response	Protection and avoidance. “Nothing really helps…I tried exercises but … not having cartilage in the knee and just the wear and tear on it over the years…you just don’t wanna make it worse.”	Protect less and use more. “the plan is good, yeah….I’m gonna probably just continue on, use my knee more, and hopefully strengthen around it and make that sort of like less painful in the knee joint …”	Active engagement with less protection.. “…I seem to be able to do more and it’s not hurting now. I mean just even just going up stairs – I can sort of do it easier, than what it used to be like… I hope it continues this way but with time I am not sure this will be enough I still have trouble kneeling and stuff like that…”
Emotional response	Fear about future ability to work and interact with kids. “I’ve got my kids playing footy now and I’d like to go and have a kick with them but I can’t… I got to be careful … it’s sad when you can’t play with your kids. Also, at work, “… you can’t say ‘I don’t want to do that job because it’s going to hurt my knee’… it’s scary and is making me sort of think about my future….my career.”	Happy about having a sensible explanation and plan.. “I was just a lot happier yesterday now that I’ve seen someone and found out that… I can sort of rectify this problem.”	Low confidence in key tasks; unsure about surgery. “I’m hoping, it’s improved that much that I wouldn’t even have to look at getting a knee replacement…it’s heading that way, I can mostly use it more, but, I’m still worried I will need one…. time will tell.”
Case 3	Pre-intervention	Early-intervention	Post-intervention	Follow up
Understanding of pain (cause)	Pain caused by joint degeneration. Further damage is inevitable. “You’ve got bone on bone… if that cushion is gone and it starts wearing away the bone structure and the contact areas I can’t expect improvement, I wouldn’t expect improvement I’d expect further deterioration and probably further pain and increased angle or – I’d like to think the reverse but I’m trying to be a realist.”	Pain caused by degeneration, protection and weakness. “My knee is worn out and I have been compensating for my knee, sort of protecting it. So, my muscles around the knee are weak and they are not supporting the knee…there is more pressure in the joint, and pain.”	Using the knee is good, but further damage is possible. “What I’ve learnt is that you shouldn’t be protecting it, it should be taking some of that pain, and making the joint work to feel better, which is what I wouldn’t have expected. I’d say there’s still some reservations about damaging a bit of bone… Well when you look at the – my x-rays like, because they’re so lop sided and um, you know out of alignment… and there’s no meniscus or cartilage there to cushion… I’m yet to be convinced.”
Pain control	Control of pain through avoidance. “Not doing things is the only way to control it really!”	Exercise may be helpful. “Some exercises that make me use my knee and make my muscles stronger. I shouldn’t be protecting my knee so much, I should be out there doing more with it.”	Exercise has been helpful. “I only get pain when I push the limits um, it’s not very restrictive at all anymore. But if I were to lunge or move quickly in tennis, I still get it…not much I can do about that.”
Behavioural response	Avoidance of important daily tasks. “Not much has helped the pain. I had deterioration in the last four years… I’ve started getting pain when I do the activities I enjoy, then going down stairs and putting socks on, you only got to bend a little fraction at a certain angle and you get that jabbing pain… quickly it (knee) just collapses and gives me a sharp and really painful short period of time and I back off – I can’t stand, it – the knee collapses. I try to avoid these activities but it’s hard.”	There are better ways to use the knee. “I learned some strategies to sort of make me use my knee in a better way, so I can do more with it”	Actively engaged but not confident “My function is less and less restricted, still some restriction… bending down to pick stuff up off the floor and drying my feet like, there’s still pinching sometimes, but less pain and I don’t feel quite as clumsy. But the damage is still there, so you never know…”
Emotional response	Frustration with loss of function and social interaction.. “It’s frustrating, but at least I know if all else fails I can get a knee replacement and so that – that’ll be compromised ability to move but I’ll be free of pain and won’t have to worry about the knee as far as that (…) we are now the old people so trying to get another social group where you enjoy socialising is as important as the activity.”	Hopeful with plan and the potential to prevent surgery. “I am hopeful that there is something I can do to improve my pain and maybe prevent surgery.”	Fearful that may still need surgery. “I fear I may not be able to avoid surgery… because of my previous experience with surgery (compromised drainage) there’s an extra incentive to avoid surgery, but you ought to be careful with it… As I said, I’m yet to be convinced this will work.”
Case 4	Pre-intervention	Early-intervention	Follow up
Understanding of pain (cause)	Pain caused by degeneration and damage in the knee. “… it’s obviously damaged so it’s swelling up … it is a hindrance…. I guess it’s a degeneration of some sort and I think spurs grow and all sorts of things happen that um, and I don’t think I have much cartilage left in the knee so – in fact there’s probably none… I had an MRI on my right and that told me that. The x-rays I had on both… said it was bone on bone.”	Broader understanding about pain and its contributors. “I know there’s inflammation….it all comes to influence it you know, what stresses are in your life and how they affect you… I understood where the physiotherapists were coming from, and where they were heading. How much things outside of your knee that you don’t imagine actually affect you.”	Biopsychosocial understanding about pain. “… now I know stress can cause problems in your body, wherever; obviously, my problem is my knees.”
Pain control	Protection and avoidance to control pain. “Being careful with my knee is the only way to have a bit less pain. I don’t want it [the knee] to give way. If there’s a nerve pain there and it suddenly grabs then I don’t know what would happen.”	Relaxation and active engagement may control pain. “New ways of using my body, protecting less and using it more. They are saying that pain is not necessarily a sign to stop, it’s a sign that you need to do more I guess to, to right the problem.”	Reframing pain helped active engagement. “Understanding it is not all about damage helped a lot, and enabled me to use it more, do more exercise, walk and even play tennis… I guess all the exercise helps inflammation and that has helped the pain too.”
Behavioural response	Exercise is provocative. “I have to be careful with my knee; it catches…. when it catches, I can’t walk or I could fall I suppose. I have to watch, I do watch it…I tried exercising and being active, but when I do a bit more with the knee, it swells up and it aches…it’s the damage in there.”	An active plan is helpful. “[The physiotherapist has] given me a plan with all the things I have to do…all very sensible, and I’ve got it on video so I can see what I’m supposed to do and all of that. I have been doing more and, it’s been good so far”	Being active is key for joint and overall health. “So generally they’re heaps better. I can do more things than I could before. I used to not be able to walk very far, now I can walk further, I can do steps and I can actually go down steps, it’s much better”
Emotional response	Fear of surgery as the only option. “Well I’ve been told there’s no option but a replacement…that scares me… so I don’t really want that so I will do as much as I can to stop that but in 5 years’ time I don’t know… and it can be quite a dehumanising process going to hospital. Especially publically…”	Relief about having a plan to self-manage her condition. “I was feeling quite lost really…. It is relieving to have a clear and sensible plan. There is hope!”	Confident about a future without surgery. “Some of the things I can do now, I couldn’t do before. It still hurts at times but I don’t worry about it anymore; I am confident it is ok and that I can keep going without the surgery…Well, personally I think it’s now up to me, to keep doing what I’m doing.”

Footnote: The Radar graphs displaying the participant’s change in patient-specific function, pain and psychological factors across the three phases of the study (Phase A – pre-intervention; Phase B – early after commencement of the intervention and post-intervention; Phase A’ – long-term follow up after commencement of the intervention). Outcomes have been adjusted so that a reduction in value indicates improvement for all outcomes. The graph ‘PRE’ graph displays average data from weeks 1 and 10 of the baseline period. The graph ‘EARLY’ displays data for week 2 after commencement of the intervention. The graph ‘POST’ displays average data from weeks 6 and 12 of the intervention period. The graph in Phase A’ displays data for one week at months 6, 9, and 12 after the commencement of the intervention.

Qualitative description using the Common Sense Model constructs across three timepoints of the study, and supporting objective data across the three phases of the study.

Figure 2. Patient-specific function and pain intensity. Simulation Modeling Analysis for significant change between baseline and treatment period over the course of the intervention (correlation of data stream with phase vector and respective p-values for patient-specific function and pain intensity). Significant values are displayed in bold. Footnote to Figure 2. NRS: Numerical Rating Scale.

Table 3. Patient self-reported outcome measures and functional tests across the three phases of the study.

Measures	Phase	Case 1	Case 2	Case 3	Case 4
Activity limitation (KOOS Daily Living Scale)	A. (week 1)	83.8	48.5	58.8	60.3
	A. (week 10)	80.9	45.6	57.3	57.4
	B. (week 12)	92.6	67.7	80.9	77.9
	Change Score (A – B)	−10.25	−20.65	−22.85	−19.05
	A’. (month 6)	94.1	61.8	79.4	76.5
	A’. (month 9)	94.1	64.7	82.3	77.9
	A’. (month 12)	97.1	75	86.8	79.4
	Change Score (B – A')	2.50	−0.53	1.93	0.03
	MCIC	8–10 points
Pain (KOOS Pain scale)	A. (week 1)	69.4	41.7	58.3	61.1
	A. (week 10)	66.7	36.1	55.5	55.6
	B. (week 12)	80.6	50	69.4	72.2
	Change Score (A – B)	−12.55	−11.1	−12.5	−13.85
	A’. (month 6)	83.3	50.80	66.7	72.2
	A’. (month 9)	86.1	53.90	69.4	72.2
	A’. (month 12)	94.4	49.40	66.7	75
	Change ScoRE (B – A')	7.33	1.37	−1.80	0.93
	MCIC	8–10 points
Pain catastrophising (PCS)	A. (week 1)	8	26	29	11
	A. (week 10)	8	28	27	12
	B. (week 12)	2	25	26	2
	Change score (A – B)	6	2	2	9.5
	A’. (month 6)	1	17	14	3
	A’. (month 9)	0	17	12	3
	A’. (month 12)	1	17	11	2
	Change score (B – A')	−1.33	−8.00	−13.67	0.67
	MCIC	6 points
Knee osteoarthritis fear & beliefs (KOFBeQ)	A. (week 1)	50	75	76	29
	A. (week 10)	51	69	74	31
	B. (week 12)	110	62	74	87
	Change score (A – B)	−59.5	10	1	−57
	A’. (month 6)	107	55	74	85
	A’. (month 9)	109	63	87	79
	A’. (month 12)	109	61	82	89
	Change score (B – A')	−1.67	−2.33	7.00	−2.67
	MCIC	Not available
30s Chair stand test (number of repetitions)	A. (week 1)	7.0	6.3	11.0	11.0
	A. (week 10)	6.5	6.0	10.5	10.5
	B. (week 12)	10.5	8.0	15.5	17.0
	Change Score (A – B)	−3.8	−1.9	−4.8	−6.3
	A’. (month 6)	10	9	15	*
	A’. (month 9)	10	8	15	15
	A’. (month 12)	10	9	16	17
	Change Score (B – A')	−0.50	0.67	−0.17	−1.00
	MCIC	2 − 3 Repetitions
	40 Metre fast-paced walk test (speed in metres/s)	A. (week 1)	1.44	1.18	1.88	1.40
A. (week 10)		1.48	1.61	2.08	1.42
B. (week 12)		1.8	1.7	2.2	20.62
Change score (A – B)		−0.34	−0.31	−0.22	−19.21
A’. (month 6)		1.932	1.739	2.198	*
A’. (month 9)		1.702	1.778	2.235	1.990
A’. (month 12)		2.010	1.810	2.198	1.896
Change score (B – A')		0.08	0.08	0.01	−18.68
MCIC		0.2–0.3m/s

KOOS (score range 0–100. High scores indicate lower knee osteoarthritis -related problems); PCS (score range 0–52. High scores indicate higher pain-related catastrophic thoughts); KOFBeQ (score range 0–99. High scores indicate lower fear and negative beliefs about osteoarthritis). *Due to COVID-19 restrictions, we could not collect data for Case 4 at this timepoint.

Figure 3. Process of change based on the Common Sense Model, for people with knee osteoarthritis undergoing CFT.

Table A1. Participants’ characteristics.

Participants	Body mass index (BMI)	Pain and disability (WOMAC)	Mental health (SF-12)	Osteoarthritis grade (KL)	Risk of poor-response (%)
Case 1	24	33	61.1	KL < 4	24.7
Case 2	29.8	77	53.6	KL < 4	19
Case 3	25.9	57	37.8	KL < 4	33.1
Case 4	27.05	57	61.9	KL < 4	23

BMI (body mass index); WOMAC (The Western Ontario and McMaster Universities Osteoarthritis Index – ranges 0–96 – higher scores indicate worse pain, stiffness, and functional limitations) – The WOMAC score was calculated from the Knee Injury and Osteoarthritis Outcome Score (KOOS); SF-12 (lower scores indicate worse mental health); KL (Kelgren-Lawrence radiographic osteoarthritis grading scale – KL < 4 indicates low to moderate joint changes).

Table A2. Pain-related psychological factors.

Data availability statement

Data for the four participants of this study is embedded in the manuscript and individually presented either in a graphic or table format.