Patient perspectives of using a single home-based exercise when eligible for knee replacement due to severe osteoarthritis: A qualitative interview study

The QUADX-1 trial

The QUADX-1 trial,^32,33 was designed to test the efficacy of a simplified exercise approach and to address gaps in the care pathway for patients with severe knee OA considering TKA. At the time, only 23% of patients received guideline-adherent non-surgical treatment prior to consulting with an orthopedic surgeon, and there was no systematic care pathway in place for reassessing of the need for TKA after referral to guideline treatments.³⁴ To improve the care pathway, the QUADX-1 trial introduced a 12-week, 1-exercise, structured, home-exercise intervention followed by a systematic re-evaluation of the need for surgery.

Additional details on the design, content, context, and results of the QUADX-1 trial are available open access from the trial protocol³³ and primary report³² as well as findings from interviews with the clinical staff involved in the trial.³⁵

The purpose of the current study was to explore patients’ perceptions (before) and experiences (after) with the 1-exercise intervention of the QUADX-1 trial and the enhancement of their care pathway. The participants’ descriptions served as determinants influencing their thoughts about the exercise intervention and the systematic re-evaluation of their need for surgery. By conducting a qualitative analysis of patient interviews, this research explored the perceptions and lived experiences of participating in the intervention as part of their care pathway.

Study design

A qualitative study design was selected, as it is well-suited for gaining in-depth knowledge of a particular phenomenon, topic, or someone’s opinions, perspectives, and experiences.³⁶ Semi-structured interviews were conducted before and after the intervention to capture and compare participants’ perceptions and experiences and explore whether their views transformed over time and why. This qualitative study was conducted in accordance with the Standards for Reporting Qualitative Research: A Synthesis of Recommendations (SRQR) checklist³⁷ (Extended data - S1. SRQR checklist). Participants for the interviews were recruited from the QUADX-1 trial, which ran from October 25^th, 2016, to January 8^th, 2019. It was registered at ClinicalTrials.gov under identifier NCT02931058 on October 3^rd, 2016.

Setting

The current study was conducted in Denmark, where the Danish welfare state provides free care for all citizens, as the healthcare system is publicly funded via taxes. The Department of Orthopedic Surgery, where this study was based, has >600 annual knee replacements and more than 45,000 annual ambulatory visits.³⁸ Following discharge from the hospital, all Danish municipalities have outpatient rehabilitation centers where patients can be referred for rehabilitation. As mentioned in the previous section, pre-habilitation (i.e., exercise before surgery) is not standard-of-care. This means that outside being referred to an orthopedic surgeon by their general practitioner (to address their need for surgery), it is essentially up to the patient to seek information, arrange, manage, finance, and adhere to a symptom management plan.

Participants

We chose purposeful sampling to ensure a broad representation of patients of varying sexes and ages^32,33 as shown in Table 1. As the participants’ group allocation (i.e., allocated exercise frequency in the QUADX-1 trial) was blinded to the interviewer (not yet allocated at first interview, and still blinded at the second), it was not possible to ensure equal allocation between groups. Patients were approached by the primary interviewer (RSH) before the baseline assessment for the QUADX-1 trial and asked whether they were willing to participate in the interviews. As transcription and initial analyses were conducted simultaneously, the participants were enrolled until no new categories were created during the review and analysis of the two concurrent interviews. Recruitment for interviews took place between 1^st of March and 12^th of December 2018. The final interview was conducted on the 26^th of March 2019.

Data collection method

Semi-structured single interviews³⁹ were conducted at two time points with ten participants during their enrolment in the trial: 1) before they started their home-based exercise intervention and 2) after they completed the exercise intervention. After the intervention, the interviews were conducted before the participant and orthopedic surgeon re-evaluated the participant’s needs for future care and made a final decision (i.e., need for surgery).

Interviews were conducted in a private clinical setting to create trust between the RSH and participants. This approach aimed to establish a calm and secure atmosphere, which was deemed important when discussing the determinants influencing patient engagement and exercise adherence.

Interview procedures

The interviews were guided by semi-structured pilot-tested interview guides containing open-ended questions (Extended data - Supplementary files S2 and S3). Both interview guides followed a “funnel approach”, starting with broad, open-ended questions followed by more focused sensitizing and probing questions. This approach aimed to generate detailed and in-depth information, allowing for an exploration of participants’ perceptions before the intervention and their subsequent experiences afterward.³⁶

The following literature informed the topics in the interview guides: coordinative efforts in managing non-surgical and surgical care for patients eligible for knee replacement,^12,40–46 knee-replacement,^12,46,47 shared decision-making,⁴⁸ contemporary organization of care and effect of exercise therapy in patients with severe knee OA (e.g. knee pain),^49–55 and lastly, patient experiences of management and/or treatment of OA symptoms through exercise therapy and surgery.^{20–22,24–26,56}

The two interview guides were developed through an iterative process between RSH, TB, and JK, focusing on the participants’ preconceptions and experiences with pre-habilitative home-based exercise using the 1-exercise program. Pilot testing was carried out by RSH with two QUADX-1 patients who were not included in the present interview study prior to data collection. Based on feedback from these pilot interviews, RSH and JK adjusted the interview guides and revised the questions that were difficult for participants to understand. RSH conducted all face-to-face interviews used for analysis, which lasted between 16 and 33 minutes (average 22 minutes).

Data processing

Data collection, processing, and analysis occurred concurrently with RSH and JK reviewing the audio recordings after each interview to identify emerging topics for exploration in subsequent interviews. The interviews were recorded using a Philips Voice Tracer LFH0882 digital voice recorder and transcribed verbatim by two assistants, with no prior involvement in the study. The fully transcribed interviews were merged into one text, totaling 182 pages, which constituted the unit of analysis. The analysis was conducted using NVivo 20 in an iterative process, following the content analysis approach described by Graneheim and Lundman.^57,58

Data analysis

RSH and BG began by reading the entire dataset (unit of analysis) multiple times to obtain a comprehensive understanding of it, in its entirety. The unit of analysis was then divided and condensed into meaning units by RSH and BG. The condensation process involved the following steps: 1) condensing the text into meaning units, while noting potential facilitators and barriers; 2) condensing the manifest meaning units, simplifying the text while preserving its essence; 3) abstracting and coding the condensed meaning units, categorizing the content based on its immediate meaning; and 4) sorting sub-categories by differences and similarities to identify patterns. To validate the initial coding by RSH and BG, a randomly selected data sample was independently coded by TB and JK, and all four code sets were compared and discussed. Once an agreement was reached between the coding of RSH, BG, TB, and JK, RSH and BG continued with the full coding process. The final phase involved developing the subcategories into categories, which reflected the underlying patterns in the data (see Table 2 for an example of the analysis).

To further explore and understand the participants’ perceptions and experiences of the 1-exercise program, tentative categories were reflected upon and discussed by RSH, BG, MSR, TB, and JK. These discussions allowed for a richer, more nuanced interpretation of the data and strengthened the validity of the results. This iterative process facilitated an ongoing reanalysis of codes, sub-categories, and categories⁵⁹ by RSH and BG, further enhancing the validity of the findings. An audit trail of the analysis, as well as a section on trustworthiness, are provided in the Supporting Information (Extended data - S4. Audit trail).

Ethics

This study was conducted in accordance with the Declaration of Helsinki.⁶⁰ All participants were informed about the study’s aims, anonymity, and confidentiality and received both oral and written information. All participants provided written informed consent to participate in the interviews. All participants were pseudo-anonymized and all reported data were de-identified (no mention of names or date of birth). The study was approved by The National Committee on Health Research Ethics under The Committees on Health Research Ethics in the Capital Region of Denmark (protocol ID: H-16025136, approved September 13^th, 2016). In addition to adhering to standard ethical guidelines, RSH applied situational ethics, assessing the interview situation based on the participants’ comfort and ease during the interview.⁶¹ Therefore, RSH acted based on his own judgment and decisions in relation to the interview situation.

Category 1 – Less-is-more, unless it is too “less”

Sub-category 1.1 – Simplicity and accessibility makes the exercise manageable and easier to initiate

During the pre-interviews, participants perceived that home-based exercise would be easy to fit into their everyday lives. Elements such as transportation to and from rehabilitation centers and flexibility when the exercise could be performed were mentioned. A participant stated:

Further, during the pre-interviews, participants perceived that being prescribed only one exercise would make doing exercise more manageable and easier to initiate. Factors like time-effectiveness and “easy to fit” into daily routines were mentioned by the participants, as described in the statement below:

In the post-interviews, when patients elaborated on their experiences, they confirmed that being prescribed one home-based exercise made it easier to manage and fit their everyday lives, as it was considered flexible. Participant 3 explained:

Sub-category 1.2 – Simplicity has a positive effect on competence and adherence

Before the participants began the 1-exercise program, they perceived that its simplicity would have a positive effect on their exercise technique and that their exercise program would be easier to master compared to a more extensive exercise program. They also perceived that simplicity would increase adherence, as Participant 8 described in the following quote:

In the post-interviews, the patients had experienced that the 1-exercise program had indeed made it easier for them to master the exercise, which had increased the likelihood of them “getting it done” (improved their exercise adherence) during the program. One participant explained how the simplicity of the intervention made it easy to remember and follow, in the following way:

Another participant elucidated another aspect of “getting it done,” emphasizing that the duration of the exercise was a crucial factor, as elaborated in the following quote:

Sub-category 1.3 – Doubt and skepticism towards the efficacy of the 1-exercise program

The positive determinants towards the 1-exercise program described in Sub-categorie s 1.1 and 1.2, were nuanced and challenged by doubt and some skepticism towards it as well. For example, in the pre-interview, some skepticism, or at least ambivalence, was presented. This pertained to whether a single exercise was sufficient to influence the need for surgery or knee pain, as seen in the quote from Participant 8:

In the post-interviews, skepticism towards the effectiveness of using only a single exercise was confirmed, mainly by participants who did not benefit from the 1-exercise program. This was expressed as experiencing a lack of pain relief or a physiological response to the exercise, for example, sweating or the muscle working hard. Most participants who mentioned experiencing a lack of pain relief and exercise “response/reaction” described that it negatively affected their motivation to continue exercising. Participant 4 explained his experience and thoughts towards the 1-exercise program in the following way:

Some participants experienced challenges during the intervention. Particularly the participants who were motivated to exercise more, as they felt “limited” by the 1-exercise approach. Others, as participant 4 quoted above, lost motivation to exercise if they did not feel a physiological response (e.g., sweating or muscle fatigue) during exercise. Therefore, both these situations present potential barriers towards adherence to the 1-exercise program.

In summary, the analysis revealed a dynamic transformation from the participants’ initial perceptions of their lived experiences with the exercise program. As it was easy to remember and required minimal time, it enhanced adherence and helped maintain motivation. Participants who perceived the program as beneficial highlighted its simplicity and accessibility as key facilitators/enablers, which facilitated integration of the exercise into their daily lives. For some, this simplicity and short timeframe became a key determinant for successfully adhering to home-based exercise with the 1-exercise program. Conversely, participants who experienced the exercise lacking in intensity or relevance experienced disengagement, underscoring the importance of aligning exercise-program elements with participant expectations. Post-interviews predominantly confirmed pre-interview perceptions, with nuances emerging when the exercise failed to meet the participants’ expectations of pain relief and exercise intensity, or when participants desired more exercise variation in their exercise program. See Extended data: Supplementary Table (S5) for a summary of examples.

Category 2 – Feedback-loops to motivation and adherence

Sub-category 2.1 – Intentions: Pain relief and avoiding surgery

During the interviews, participants identified two central motivation drivers (intentions) that influenced their adherence to the 1-exercise program: the desire to 1) achieve pain relief and 2) avoid surgery. Their desire to achieve pain relief originated from their limitations in activities of daily living and the negative impact it had on their quality of life. The motivation to avoid surgery was driven by perceptions of and previous negative experiences with anesthesia and surgery. Negative experiences included problems with sick leave, conflicts with other life-challenges taking up time (compounding life-challenges), fear of anesthesia, and the risk of post-surgical complications. Participant 4 described his motivation to avoid surgery as follows:

In the post-interviews, the participants’ experiences did not alter their end goal of achieving pain relief, nor did they wish to avoid surgery. Many patients experienced a reduction in their knee pain by adhering to the 1-exercise program and had improved their level of physical function, which positively affected their quality of life. The participants who experienced pain relief from the exercise intervention found that it aligned with their desire to avoid surgery and felt motivated to adhere to and continue exercising as they did not need surgery in the future. Participant 2 described the benefits of exercise and motivation as follows:

Not all participants were able to adhere to the exercise intervention, and some lost their motivation to continue the exercise during the 12-week intervention period. Participants explained that increased knee pain and challenges with fitting exercises into a busy schedule limited their adherence. The quote below describes one such experience.

Sub-category 2.2 – An artifact as a reminder and mediator for changing habits

In the pre-interviews, some participants implied that the elastic exercise band could serve as a reminder to help them develop exercise into a new habit. The simplicity and physical size of the elastic exercise band – compared to the “bulky” exercise equipment commonly seen in fitness centers – was expected to make it suitable to have at home without taking up much space while being a reminder to exercise. Participant 7 described her thoughts towards exercising with an elastic band:

After the exercise intervention, the participants who employed this strategy confirmed that having the exercise band visible at home helped them remember to exercise and form a new (exercise) habit. Participant 3 explains:

After the exercise program, both having success in establishing exercise as a habit and having elements in place to support it were highlighted as important for exercise adherence. Scheduled and structured time points, calendar reminders, and time-effective solutions where exercise could be completed while doing something else, such as cooking, were thereby linked to improving adherence. Participants 6 and 8 explained their approaches.

Participant 9 attempted to form a habit by integrating both the artifact reminder (elastic band) and coupling it to the daily routine:

Some participants described how the artifact (the exercise band) influenced and/or was integrated into their routines or behaviors (habits). Others attributed combinations with daily routines or scheduling to improve adherence. Having the artifact physically visible in the participants’ daily environment facilitated adherence to the exercise routine, and some participants successfully integrated with daily routines, opening the possibility of forming a habit.

Sub-category 2.3 – Social influence and commitment

Before the exercise intervention, some participants described that their relatives were important for supporting their motivation and adherence during the 12 weeks of the 1-exercise program. Relatives were mentioned to function as both motivation boosters and exercise reminders. Participant 10 explained:

After the exercise intervention, the influence of relatives in supporting exercise adherence and maintaining motivation was confirmed by participants. Receiving praise for effort and using humorous inputs to maintain positive energy around exercise were described as examples. The following quote describes one of these situations:

By contrast, other participants in the post-interviews expressed that support from others was not important for their motivation or exercise adherence. Some participants stated that they preferred to exercise alone, as quoted by Participant 7:

While reflecting on what they expected of benefits from home-based exercise, the participants mentioned that follow-up visits with the physiotherapist could become important. Uncertainty about the correct exercise technique and timely correction were mentioned as potentially important aspects of the follow-up visits by the physiotherapist. Participant 6 said the following:

The importance of the social influence of the follow-up visits with the physiotherapist was also confirmed by the participants in the post-interviews, where these visits were described as being very important to their experience with the exercise. Examples such as adjustment of exercise technique and elastic band resistance, pacing, reminders to regularly exercise, questions related to experienced symptoms or pain, and how to react to these were mentioned in relation to follow-up visits with a physiotherapist. Participant 4 responded as follows when asked what he gained from the follow-up visit:

However, not all participants preferred a home-based setting, and some expressed that they preferred supervised exercise sessions at an outpatient rehabilitation center. They believed that the presence of a physiotherapist in a rehabilitation setting would ensure a better result and increase motivation and adherence, especially in the long term. One participant explained this as follows.

Most participants mentioned that a positive and supportive social environment facilitated motivation and adherence. This was not unanimous though as some participants preferred to exercise alone and described that they had no need (at neither pre- nor post-intervention) for social support or group exercise sessions to stay motivated and adhere to the exercise program. Monthly follow-up visits with physiotherapists during the exercise period were generally described as facilitating adherence to the home-based exercise. The lack of a “social commitment” was a barrier for participants who described having accountability towards the physiotherapist or an exercise group, helped them not skip sessions, or cut exercises short (out of discomfort). Interestingly, all these preferences were presented in the pre-interviews, suggesting that they were based on prior experiences.

In summary, the transformation from initial perceptions to lived experiences with the exercise intervention revealed key factors influencing the individual’s motivation and adherence. While the core goals of reducing pain and avoiding surgery remained unchanged, pain paradoxically acted as both a facilitator and a barrier to exercise. Time constraints persisted as a barrier for all, but facilitators such as visible reminders (e.g., the elastic band), structured routines, and social support were frequently presented as pivotally important in maintaining the adherence of individual participants. These findings highlight the interplay between personal intentions, practical tools, and external influences in maintaining adherence and motivation to a home-based exercise program. Extended data: Supplementary table S5 provides an overview of the results.

Category 3 – Comprehensive re-assessment and healthcare-support empowers patient-centered care

During the pre-interviews, all participants were positive towards their need for surgery, being evaluated both before and after the 12-week program as part of the clinical care pathway. The trial design ensured that participants were reassessed for their surgical needs directly after the exercise intervention. The participants described that this process seemed sensible and reassuring in re-assessing their need for surgery directly after completing the exercise program. Ultimately, it was intended to reduce knee symptoms. This issue was brought up by participants, who described that the system of referrals to test and diagnose their knee at times felt poorly coordinated with long waiting times (multiple physical sites/wards and no healthcare professionals that follow them across). This led them to feel that they had to fend for themselves and that they were left to their own devices (i.e., without adequate support).

Participants expressed that it was positive to try an alternative to surgery, and that the coordinated care pathway supported them well. Participant 4 explained:

When the participants reflected on this coordinated care pathway, which ensured that they were re-assessed after exercise, the positive elements mentioned before the intervention were repeated after the intervention. For example, when participants did not experience any changes in their knee symptoms during the exercise program, it gave them peace of mind to know that they were scheduled to re-evaluate the need for surgery after the exercise program was completed. The participants who experienced an improvement in their symptoms (e.g., decreased knee pain) after exercise also appreciated the re-assessment because they were given confirmation by the orthopedic surgeon that they could safely postpone surgery and continue exercising. In both scenarios, the participants described that knowing they would be reassessed created a sense of security, or control, in their care pathway. This was a recurring experience for all participants, for example, in the way Participant 7 explained:

In summary, the transformation from initial perceptions to lived experiences with the coordinated care pathway, including a systematic re-assessment of surgical needs, was universally valued by the participants. It contributed to a sense of security, patient empowerment, and instilled trust in the care process. The care pathway helped create a structured and supportive environment that facilitated adherence to the exercise program while also ensuring that surgical decisions were well-informed.

Despite the facilitating aspects of the coordinated care pathway, challenges related to the broader healthcare system, such as long waiting times and fragmented services, were still noted. However, the reassessment process itself was a key facilitator, enhancing participants’ confidence in their care plan. This highlights the importance of a cohesive and patient-centered approach that empowers the patient and supports informed decision-making.

Behavioral change

If we view our results regarding simplicity and short timeframe through a theoretical lens of behavioral theory,⁶² it provides insight into how these determinants influenced participants’ adherence to the 1-exercise program. Participants’ capabilities, motivations, and opportunities played a significant role in their adherence to exercise. For many, the simplicity of the 1-exercise program enhanced participants’ capabilities (knowledge and skills) and facilitated adherence. Similarly, a short duration of exercise sessions boosted adherence and sustained motivation by integrating into daily routines with low effort. These findings align with those of other studies demonstrating the effectiveness of simple(r) exercise programs for adherence across various patient populations.^63,64 However, participants desiring a more varied exercise program often found the program’s simplicity to be a limiting factor, posing a barrier to some wishing to engage in more, or different, exercises (confined by the QUADX trial intervention). As posited in Self-Determination Theory (SDT), unfulfilled expectations negatively affect motivation.^65,66 In the above interviews, unmet psychological needs, such as unfulfilled expectations of pain reduction or a physiological response, were described to negatively influence motivation and adherence.

Adherence and social influence

To better understand adherence, we need to examine how social and contextual factors influence participants’ experiences. For patients with mild-to-moderate knee OA, a common exercise care package in Denmark is the GLA:D program, which is commonly arranged as a combination of supervised and home-based exercise via outpatient clinics⁶⁷ – the supervised component is frequently structured as group-exercise with set timepoints at outpatient clinics. In contrast, the participants in this study experienced that the advantage of home-based exercise was flexibility and ease of integration with daily routines, precluding the need for planning and spending time on transportation to outpatient clinics. This resonates with findings in a study of patients managing shoulder pain, where home-based exercise programs simplify the integration of exercise into daily life.⁶⁸ This suggests that the role of physiotherapists, as exercise supervisors in the care of patients with knee OA, is less important to some participants once thorough exercise instructions have been provided when the exercise program is simple. This contrasts with other studies in which physiotherapists are positioned with a fundamental role in promoting adherence to treatment^68,69 or where they are positioned as a driving force in dismantling inequalities in social power to achieve better health.⁷⁰ Several participants in this study also supported the importance of the physiotherapist, pointing out that the monthly follow-up visits with physiotherapists were perceived as important (pre-intervention) and transitioned to being experienced as very important (post-intervention). The ambiguity could stem from the participants’ unique preferences for organizing their exercise setup to align with everyday life, as well as their diverse perceived needs for follow-up with the physiotherapist. These contrasting perspectives suggest that adherence may be better facilitated in a personalized, preference-based approach with or without exercise supervision after the initial instruction and depend on how the patient’s needs change over time. The pre-planned follow-up visits, with both physio- and surgeon, helped mitigate potential uncertainty related to correct exercise technique, clarifications around knee OA-related symptoms, and provided structure in the care pathway. This need for a balance between supportive independence and the provision of professional support underscores the nuanced interplay between behavioral determinants and social influences in shaping adherence.

Some participants described an uncertainty regarding “correct” exercise technique, which could be an indicator of why they prefer supervision by the health professional, as they fear that exercising incorrectly could worsen their condition. Such uncertainty (or fear avoidance) has been observed in other studies in populations of adults with various long-term illnesses (stroke, low back pain, cancer, etc.),⁷¹ hip and knee OA,^21,11 and knee OA populations,²² which have concluded that structure and a plan for exercise can influence motivation for supervised exercise. The importance attributed to health professionals touches upon elements of social influence, such as authority and source credibility, as described by Cialdini and Pratkanis,^72,73 where the influence of physiotherapists as credible healthcare professionals facilitates patients to exercise and maintain their adherence. It is not unthinkable that the authority and credibility of the physiotherapists helped mitigate fear avoidance in the current study, which has also been reported in previous reviews of OA populations.⁷⁴ These diverse perceptions and experiences suggest that home-based exercise fits the preferences of some patients, but not all, and that clarification of the patient’s preferences towards this should be considered a part of individualized care.

Key desires driving exercise motivation and adherence despite skepticism

The motivation for non-surgical care (e.g., exercise) can be low in patients with knee OA, as many do not believe that exercise will help reduce knee pain.^10,24,75,76 This skepticism was also mentioned by participants in this study, who questioned the efficacy of the 1-exercise program. Despite this, the participants highlighted two key desires that motivated them to engage in exercise: (1) avoiding surgery and (2) achieving pain relief. Fear of anesthesia and surgical procedures was a central factor driving their desire to avoid surgery, often influenced by negative personal experiences or stories from family members and friends about poor surgical outcomes, which is consistent with previous findings.^21,75,76

Most participants were motivated to exercise during the 12-week period. These motivated participants had predominantly had a reduction in knee pain and an improvement in their physical function. They felt that exercise improved their quality of life, which stimulated their motivation to continue. Many patients in the QUADX-1 trial chose to postpone joint replacement surgery, likely attributable to improvements in pain and physical function.³² The participants who experienced pain relief from exercise likely changed their behavior and became able to self-manage their knee OA condition and adherence, with minimal contact with healthcare professionals during the trial. Some participants attributed part of this improved self-management ability to the simplicity of the exercise, which could, at least theoretically, result in long-term adherence.²⁰

Habits, artifacts, & cues

The change in behavior could be attributed to the acquisition of a new habit, that is, exercise became a habit. A habit is defined as ‘an automatic response to contextual cues, acquired through repetition of behavior in the presence of these cues’.⁷⁷ Several participants mentioned that the elastic exercise band functioned as a reminder (cue). This experience is supported in the literature, where reminders are recognized as effective when changing behavior.^78,79 A key predictor of behavioral change is intention.⁸⁰ Intention refers to an individual’s motivation related to the performance of a given behavior (e.g., exercise to avoid surgery or pain relief ). The connection between intention and behavioral change is moderated by the strength or power of the intention (how much something is desired),⁸⁰ but also by the degree to which the behavior is habitual.^81–83 In this process, the elastic exercise band can function as a mediator, supporting a gradual shift in cognitive control from intentional to automatic behavior (a habit). When a habit is formed, cognitive shortcuts are used and less scrutiny is applied to the consequences of a new behavior.⁸⁴ Further, when the response to a new behavior satisfies a person’s motivation (intention) to engage in exercise (i.e., leading to pain relief or avoiding surgery), it facilitates a degree of automaticity – exercise can become a habit. This was seen in the interview excerpts above, where Participant 2 described that the 1-exercise program enabled her to walk to the station again, which motivated her to continue exercising. According to affordance theory, what an artifact affords (i.e., what one can do with it) is significant in how individuals use the artifact and, over time, learn and adapt while using it.⁸⁵ Participants described keeping the elastic band in sight to remind them to exercise, which is a good example of developing an affordance, in action, for example, when one participant described contempt for bulky exercise equipment, but not for the elastic band. In this example, the participant linked the perceived benefits of the exercise with the elastic band (artifact) and adapted their perception of the exercise equipment from something they did not want at home into something useful. The use of the elastic band in the 1-exercise program thereby provided participants with an opportunity to learn and adapt their exercise setup. It did so by affording a setting via an artifact that could remind them to elevate their motivation and improve the potential for adherence. Several participants described their spouse or family members, reminding them to exercise, which helped their adherence. Lack of social support has previously been described as a barrier to physical activity in OA populations,⁷⁴ which was not detected in the current study.

Simplicity – boon or bane?

The simplicity of the 1-exercise program presented both strengths and limitations. The straightforward approach helped many maintain confidence in their ability to perform the exercise correctly and consistently, where others found it insufficient to meet their needs. These participants, particularly those with previous exercise experience, missed physiological responses such as muscle fatigue or sweating, which they associated with effective workouts. Without these bodily feelings, they struggled to perceive the exercise as “real” or “effective”, which led to a loss of motivation. This lack of physiological response (or reaction) became a barrier and caused a loss of motivation, which confirmed an expectation in the pre-exercise interviews that it might not be sufficient.

A similar loss of motivation was also seen in a study of two-year exercise adherence for persons with knee osteoarthritis, where ambivalence towards the benefits of exercise was described in participants with low exercise adherence.²² The 1-exercise program was, however, also positively attributed as being “easy” and tangible/manageable, which led to higher confidence in mastering the exercise technique and improved exercise adherence. Participants expressed that the simplicity of the 1-exercise approach made supervision at every exercise session unnecessary and that it fit well with the home-based setup. In the current study, we observed that participants were driven by the intention to reduce pain and avoid surgery, both of which, we argue, are strong drivers of intent. As mentioned in the background section, long-term adherence (habit formation) to exercise is difficult to achieve. Considering that effective exercise reduces both pain and the intention to alleviate it (along with the perceived need for surgery), it is not surprising that a person may stop exercising when driving intent wanes. Interestingly, participants also lost motivation when they found the exercise ineffective or inadequate. We believe that this underscores a primary challenge with long-term adherence to therapeutic exercise, being that it is either deemed “effective, but not necessary anymore” or “in-effective for me”. The review cited at the end of the previous section also described a similar pattern, named “no pain, no maintenance” in relation to OA populations and exercise/physical activity.⁷⁴

The coordinated care pathway

All participants expressed a positive attitude towards the idea of the coordinated care pathway, which included systematic follow-up and reassessment. Their progress during the exercise program was monitored once per month by a physiotherapist, and their need for surgery was reassessed after the 12-week exercise period by the orthopedic surgeon. This ongoing contact and support was confirmed at follow-up interviews, echoing findings reported from previous research on therapy-based exercise in populations with long-term health conditions.⁷¹ While similar studies have shown the value of coordinated care efforts in other chronic conditions, to the best of our knowledge, this is the first such presentation for patients with knee osteoarthritis (OA) severe enough to be eligible for knee replacement. For both the follow-up visits at the physiotherapist and orthopedic surgeon, the participants described that the coordinated care pathway created a sense of security and structure in their care pathway. A sense of security is a complex emotional state in which individuals feel safe, confident, and free from doubt.^86,87 The planned reassessment after exercise provided a foundation for the participants to feel safe and confident about the next steps in their care pathway, reinforcing the sense of security in managing their knee OA. This concept of a sense of security is comparable to the concept of “safety netting” where planned follow-up assessments and advice on symptoms are highlighted as important for patients’ experiences with their care pathway.⁸⁸ Such findings are not unique to knee OA, as similar findings have been observed in other contexts, such as planned follow-up rehabilitation after total hip arthroplasty.^89,90 In those studies, planned follow-up and structured care pathways were found to improve patients’ confidence in their recovery, similarly to the current study.

Determinants in implementing coordinated care pathways for knee OA patients in the Danish Healthcare System

Previous reviews have found that patients undergoing therapy-based exercise often feel abandoned if they are left to self-manage their exercise.⁷¹ The 1-exercise program, however, applied a coordinated care pathway that included a planned reassessment, which may have mitigated such feelings of abandonment. Continuous follow-up and systematic re-evaluation could play an important role in the participants’ overall positive reception of a program. In the current study, it appears to have aligned well with the participants’ desire for structured support and reassurance regarding their knee OA management. As shown in our study, participants reported feeling more confident and secure in their exercise routine, knowing that they had scheduled check-ins with healthcare providers. This sense of security reinforced their commitment to the program as it helped them feel that their needs were being adequately met and that they were not navigating the exercise regimen alone.

At the time the interviews were conducted, the Danish Healthcare system lacked a systematically implemented coordinated care pathway, similar to the model applied in the QUADX-1 trial. As a result, many patients with knee OA are left to self-manage their care without consistent follow-up or guidance, potentially undermining their adherence to recommended non-surgical treatments such as exercise. The current study suggests that this gap in care provision could be a barrier to long-term adherence, as some participants expressed concerns about the limited structure and guidance of standard treatment pathways. For those in the 1-exercise program, however, the regular re-assessment not only supported their continued motivation but also helped to manage their expectations about the program’s efficacy, especially considering initial skepticism regarding whether one exercise could provide pain relief. Such skepticism was previously reported among orthopedic surgeons towards the long-term efficacy of exercise therapy for knee OA patients, particularly those eligible for knee replacement.³⁵

In the context of the Danish healthcare system, where non-surgical care was predominantly managed in general practice, implementing a coordinated re-assessment plan could bridge this gap and provide patients with the ongoing support they need. By systematically re-evaluating patients following first-line treatment (i.e., weight management, exercise, medication), healthcare providers could better support patients in maintaining their motivation to exercise and preclude a feeling of abandonment that often arises when patients are left without guidance after initial consultations.

Implications for (therapeutic) practice

To improve exercise adherence when using a simplified exercise intervention, such as the 1-exercise program, for patients with knee OA, we recommend the following: