The influence of an 8-week therapeutic exercise program on the patient experience of patellofemoral pain: a qualitative descriptive study

ABSTRACT Objective The aim of this study was to explore patients’ experience of patellofemoral pain (PFP), in order to help improve the mutual understanding between the patient and the physiotherapist and consequently enhance the efficacy of treatment. Methods A qualitative study design with focus groups was used to explore patient experience prior to the implementation of the therapeutic exercise program, during its duration, and up to twelve months after its conclusion. Results Patients provided a detailed description of their lifestyle prior to the enrollment in the therapeutic exercise program, their experience of the therapeutic exercise program and the behavioral changes that remained after its conclusion. Three main themes emerged from our data: 1) PFP characteristics and the impact of PFP on daily life; 2) experience with the therapeutic exercise program; and 3) changes in PFP and daily behaviors following the therapeutic exercise program. Conclusion Our findings suggest that a targeted therapeutic exercise program effectively reduces short- and long-term PFP and enhance overall well-being. Further research is needed to investigate the effects of different therapeutic exercise programs with a focus on the role of self-motivation.


Introduction
Patellofemoral pain (PFP) is one of the most common knee conditions that affects almost 23% of the general population at some point in life, with the point prevalence in adolescents being 7.2% (Smith et al., 2018b). Although clinical symptoms may vary among patients, pain around or behind the kneecap is aggravated by everyday activities such as squatting, running, prolonged sitting, jumping or stair climbing . Such a broad variety of pain-inducing activities may put a significant strain on a person's life as they are forced to adapt to a new, more vigilant lifestyle. Furthermore, a long-term study on 22 patients has reported that 91% of the patients diagnosed with PFP in childhood continue to experience knee pain for up to 18 years after the initial diagnosis (Stathopulu and Baildam, 2003), while another study has established that 57% patients continue to have significant symptoms (i.e. severe pain and functional impairments) up to 8 years after the initial diagnosis (Lankhorst et al., 2016). Additional evidence showing that approximately one quarter of PFP patients eventually stop participating in sports activities (Rathleff, Rasmussen, and Olesen, 2012) highlights the need for designing, implementing and evaluating effective therapeutic exercise programs for this condition.
Exercise programs tailored to alleviate specific impairments are recommended to reduce PFP in the short, medium and long term, as well as to enhance functional performance in the medium-and long-term (Crossley, van Middelkoop, Barton, and Culvenor, 2019). Recent systematic reviews have encouraged the use of resistance training targeting proximal muscle groups in addition to the knee muscles (Lack et al., 2015;Manojlović and Šarabon, 2020). However, exercise descriptors are still inconsistent. Thus, poor long-term outcomes may originate from disregarding specific characteristics of different subgroups of PFP patients. For example, unlike adults, adolescents with PFP do not exhibit deficits in quadricep strength (Rathleff et al., 2013) and show greater hip muscle strength, which can be probably attributed to the fact that up to two thirds of adolescents with PFP are highly active and engage in sports activities (Rathleff, Roos, Olesen, and Rasmussen, 2015).
Although often overlooked, psychological factors such as kinesiophobia and catastrophizing have emerged as important factors to be considered in the management of PFP (Domenech, Sanchis-Alfonso, López, and Espejo, 2013;Piva et al., 2009). Health beliefs have already been well examined in patients with low back pain (Wertli et al., 2014) and shoulder disorders (Jones, Hanchard, Hamilton, and Rangan, 2013) while knee conditions have only lately received increased attention. A recent qualitative study of people living with PFP has identified several psychological problems, including loss of selfidentity, physical and functional abilities, and painrelated confusion and fear (Smith et al., 2018a). Robertson, Hurley, and Jones (2017) have studied people's beliefs about the meaning of crepitus in PFP. They have concluded that crepitus may elicit negative emotions and unfounded etiological beliefs as well as eventually alter behavior. However, to the best of our knowledge, no study to date has qualitatively assessed the effects of an implemented therapeutic exercise program on the experience of living with PFP. Therefore, this study explores the effects of an 8-week therapeutic exercise program on the perceptions and experiences of people with PFP before, during, and after the implementation of a therapeutic exercise program. This in-depth understanding may benefit both people with PFP and physiotherapists seeking long-lasting and improved clinical outcomes, as well as open up a new direction in physiotherapy research. The research question we set for this study was: Do the perceptions and experiences of patients diagnosed with PFP change after their participation in an 8-week therapeutic exercise program?

Design
A qualitative descriptive study design with focus group (FG) discussion upon completion of the therapeutic exercise program was used to explore the patients' experience of PFP before, during and after the implementation of the therapeutic exercise program. The last focus group was conducted within one year from the conclusion of the intervention. The qualitative descriptive study design is widely used in health science research as it summarizes factual and everyday language through which it is possible to gain an in-depth and accurate understanding of patients' perspectives, experiences and beliefs (Colorafi and Evans, 2016). The FG method was chosen as it offers the researcher an opportunity to study how patients collectively make sense of a phenomenon and construct meaning around it (Bryman, 2015). Both an inductive and deductive approach was used. This hybrid approach was used in order to allow new themes to emerge while testing preexisting concepts (Fereday and Muir-Cochrane, 2006). The inductive approach was used to explore the patient experience of PFP before, during and after the implementation of the therapeutic exercise program as well as the impact this condition has on their daily lives. The deductive approach was used to answer the question whether people change their daily habits and behaviors after participating in the therapeutic exercise program (Bryman, 2015). Thus, a topic guide was created based on the study objectives and interview organization, with a view to facilitating the distribution and coding of information. The deductive approach was chosen to address and analyze all contextual (i.e. intrinsic and extrinsic) elements related to the experience of PFP before, during and after the implementation of the therapeutic exercise program. The checklist Consolidated Criteria for Reporting Qualitative Research (COREQ) was used to ensure that all the important aspects of the research team, study methods and context, analysis and findings were reported (Tong, Sainsbury, and Craig, 2007).

Patients
A purposive sample of four male and ten female patients of all ages diagnosed with PFP by a sports physician participated in the 8-week therapeutic exercise program. The patients were recruited after presenting at a sports clinic. They were diagnosed with PFP if they experienced both: 1) knee pain ≥ 3 on the Visual Analogue Scale during at least two of the following activities: stair climbing or descending, squatting, jogging, jumping, isometric quadriceps contraction or prolonged sitting with knee flexion greater than 90° (Rasti, Rojhani-Shirazi, Ebrahimi, and Sobhan, 2020); and 2) positive patellar compression or tilt test (Nakagawa, Moriya, MacIel, and Serrão, 2012). The patients were included in the study if they enrolled in the therapeutic exercise program and attended at least 80% of the exercise sessions. Patients were divided into two consecutive groups and enrolled in a professionally guided and deficitoriented exercise program. Each patient received an individualized exercise plan based on their previously determined deficits. The patients attended the therapeutic exercise sessions 3 times a week, while performing home therapeutic exercises in the days between. All patients were contacted by e-mail or phone ten to twelve months after completing the program and being recruited to participate in focus groups. One patient declined to participate, while two were unable to attend FG due to personal reasons. The remaining fourteen patients were allocated to three different FG based on their demographic characteristics to achieve group homogeneity. According to Guest, Namey, and McKenna (2016), three focus groups are sufficient to identify most prevalent themes within a data set.

Data collection
Data were collected in December 2020, ten to twelve months after the exercise program concluded. All patients gave written and verbal informed consent to participate in FG after receiving full written and verbal information about the study. The study was approved by the Slovenian National Medical Ethics Committee (0120-99/2018/5). The International Classification of Functioning model was used as a base for data collection, since the psychosocial aspect of PFP was being assessed (World Health Organization, 2001). Due to epidemiological reasons (the COVID-19 outbreak), all FG were conducted remotely using online tools (synchronous online FG) and recorded on a digital audio recorder after obtaining the patients' informed consent. No notes were taken during FG to reduce interruptions in the conversation. Instead, reflective notes were taken after each FG on the basis of relistening and pausing of the recording (Robertson, Hurley, and Jones, 2017;Smith et al., 2018a). All FG were conducted by the same researcher, who is experienced in clinical physiotherapy and is also gaining experience in qualitative data collection. The process was controlled and supervised by two senior researchers, both experienced in clinical practice, qualitative data collection and focus group conduction. No other relationships existed between the researcher and the patients.
There was no pre-set time limit on the duration of FG. Each FG lasted approximately 45 minutes and was transcribed afterward. As in the previous studies focusing on low back pain (Ogwumike, Bashir-Bello, and Kaka, 2020;Traeger et al., 2020) FG with semistructured questions were conducted to identify different aspects of PFP related to the implemented therapeutic exercise program which included: 1) Level of physical, psychological and social well-being and experience of PFP before, during and after participation in the therapeutic exercise program; 2) Limitations in sports and daily activities before participation in the therapeutic exercise program; 3) Difficulties encountered at baseline and during and after the implementation of the therapeutic exercise program as well as its effect on physical, psychological and social lifestyle; 4) Personal discipline including home therapeutic exercises, attendance and compliance with knee loading instructions, and medium and long-term influence of the therapeutic exercise program on habits and behavior; 5) Overall experience with the therapeutic exercise program and suggestions for further improvement; and 6) a topic guide including questions which also elicited spontaneous discussion among patients (i.e. How did your PFP influence your daily living prior to enrolling in the therapeutic exercise program; Have you experienced any limitations in terms of daily or sports activities due to PFP; How did you experience the start of the therapeutic exercise program and did you have any difficulties; How would you evaluate the effect of the therapeutic exercise program on your quality of life during its implementation; What limitations and obstacles did you encounter during the implementationof the therapeutic exercise program; How would you evaluate the effect of the therapeutic exercise program on your quality of life immediately after its conclusion; Has participating in the therapeutic exercise program had any lasting effect on your habits and behaviors; How did you family and friends influence you during the implementationof the therapeutic exercise program; How would you briefly describe the effect of the therapeutic exercise program on your daily life; and Based on your experience, do you have any suggestions for improving the therapeutic exercise program?

Data analysis
The researcher transcribed each FG audio recording immediately after FG's conclusion. The transcripts were entered into pre-prepared spreadsheets in MS Word Software (Version 2019, Microsoft, Redmond, Washington, USA). Data obtained from FG were analyzed thematically according to Bryman (2015): 1) transcripts were read and re-read several times by all researchers to ensure that they were thoroughly familiar with the dataset before they begun with the initial coding; 2) researchers then generated initial codes; 3) clustered codes into themes; 4) evaluated the higher-order codes of themes/sub-themes and named them; 5) examined the links and interconnections between the concepts and how they vary in terms of the cases' characteristics; and 6) wrote a compelling narrative about the phenomenon with examples that justify the identified concept.
Several measures were taken to ensure trustworthiness of the study. The investigator triangulation was used to minimize bias and enhance the trustworthiness of the results (Salazar, Crosby, and DiClemente, 2015). Thus, the codes were analyzed and discussed by two researchers, both experienced in qualitative data collection and FG conduction. The final conceptualization of findings was achieved with a consensus among all three researchers. During the analytical phase, fieldnotes were taken with critical reflection on the research process, which was possible due to the linear, six-phased method of thematic analysis. The researchers kept this process logical and well documented in all phases of the study, not only to achieve dependability but also transferability (Nowell, Norris, White, and Moules, 2017).

Results
Fourteen patients (four male and ten female) with PFP included in the 8-week therapeutic exercise program participated in three FG. Seven patients were aged between 10 and 20 years, all of them female; two patients (one male and one female) were aged between 21 and 30 years; three (one male, two females) were aged between 31 and 40 years; one, a male, was aged between 41 and 50 years, and another male was above 50 years of age. The patients' characteristics are presented in Table 1.
Three main themes emerged from FG data, extending further into specific sub-themes ( Figure 1). Each theme was present in all three FG and was relevant to the research question. All the themes are presented here in the chronological order in which they appeared.

PFP characteristics and their impact on patients' lifestyle
The patients provided a detailed description of their lifestyle before participating in the therapeutic exercise program. Many began by explaining the duration and etiology of their PFP. In accordance with the tendency of  PFP to become a chronic knee condition, most patients reported experiencing PFP for 3 or more years. The onset of PFP was widely attributed to inappropriate training or the overuse of the lower extremity: Although coping with physical pain was the prevalent challenge for most patients, many noticed an important impact of PFP on their psychological well-being: Participation in any kind of sport was generally banned, which was killing me. This was one of the worst periods. Prohibition of movement is a cruel punishment for me.

I got on my own nerves because I was always complaining and feeling grumpy. (F_27)
Finally, a particular but important aspect of the lack of social understanding emerged. PFP is by nature a condition that greatly affects women and adolescents and, accordingly, six female adolescents participated in our study. All of them described a lack of trust and understanding from others and their openly expressed doubts about the patients' PFP:

Experience of the therapeutic exercise program
During FG, the patients emphasized several times that they were glad they had the chance to participate in the therapeutic exercise program. They commented on the organization of the program, indicating their satisfaction with the coach, the lead researcher and the whole team: However, a few patients pointed out some organization weaknesses. These were mostly related to the schedule of the therapeutic exercise program. With their daily duties, patients found it stressful to get to the location of the therapeutic exercise program in time: Self-motivation was associated with the reported attendance and commitment to the therapeutic exercise program. The patients seemed to be highly motivated to participate in the program as they soon noticed positive changes regarding their PFP. Another factor that affected participation in the therapeutic exercise program was social support. Six adolescent patients participated in our study, and they were particularly affected by social support because they depended more than other patients on their social environment for understanding and transportation. The adult patients also described their social environment as supportive and understanding:

PFP relief and patients' behavior after the conclusion of the therapeutic exercise program
The patients expressed their satisfaction with the improvements regarding their PFP immediately after the conclusion of the therapeutic exercise program. Thirteen patients described short-term effects on PFP relief and improvements in daily function: However, one patient reported an increase in PFP immediately after the conclusion of the therapeutic exercise program: I actually felt more pain right after the program. Maybe I was exaggerating a bit or doing some exercise wrong.
Some patients found it difficult to maintain their level of commitment to the therapeutic exercises without the support and guidance of a professional coach and a support group. However, a long-term positive effect on PFP relief was expressed by ten patients: One of the main goals of the therapeutic exercise program was to affect patients' habits and behavior after its conclusion. Patients gave a rich description of how they incorporated the newly gained knowledge into their daily life after the conclusion of the program:

Discussion
This study expands the existent knowledge on PFP that has been established through quantitative research. We aimed to understand how a targeted therapeutic exercise program influences the experience of PFP. Three main themes emerged from our data: 1) PFP characteristics and their impact on daily life, 2) experience of the therapeutic exercise program, and 3) PFP relief and patients' behaviors following the therapeutic exercise program. One of the key findings of this study is that a targeted therapeutic exercise program can greatly contribute to the physical, psychological and social well-being in patients with PFP. To fully understand this common condition, we initially asked the patients to describe their overall wellbeing in relation to their perceived PFP. The patients described difficulties in coping with daily life challenges as their PFP limited them. This finding is consistent with a previous study by Smith et al. (2018a) who reported a profound loss of physical ability in patients with PFP. Moreover, a significant impact of PFP on psychological well-being was noticed before the implementation of the therapeutic exercise program. It has also been suggested that chronic pain may exert a significant impact on social life (Harris, Morley, and Barton, 2003). The patients in our study viewed their inability to fully participate in sports and daily activities as a source of personal frustration. Previous research has determined that the inability to find an underlying reason for chronic pain may lead to further catastrophizing (Van Wilgen, Van Ittersum, Kaptein, and Van Wijhe, 2008). Regardless of the uncertainty regarding the etiology of PFP (Glaviano, Bazett-Jones, and Norte, 2019) many patients try to explain their condition.
Growing quantitative evidence has shown a positive effect of muscle strengthening programs on PFP (Saltychev et al., 2018). However, to the best of our knowledge, this is the first study to explore patients' experience with such a targeted therapeutic exercise program. Many patients expressed satisfaction with the overall organization of the program and appreciated its simplicity and effectiveness. Similar results were reported for patients participating in multidisciplinary programs treating knee osteoarthritis (Lawford et al., 2021) and focusing on fall prevention (Finnegan, Bruce, and Seers, 2021). Accordingly, the patients in our study were highly committed to the program. However, after the conclusion of the therapeutic exercise program, many patients reported difficulties in adhering to home therapeutic exercises. It has been previously suggested that up to 50% of the patients who participate in aerobic exercise programs stop doing the prescribed exercises within the first six months, even though regular physical activity is known to be essential for maintaining the achieved health benefits (Robison and Rogers, 1994). Therefore, it is important to focus on the long-term maintenance of self-motivation in PFP patients. This could potentially be achieved through a pre-set schedule that includes follow-up checkpoints. Moreover, educating patients about their condition and the importance of performing home therapeutic exercises has been shown to have a positive impact on PFP (Rathleff, Roos, Olesen, and Rasmussen, 2015).
Another important finding of this study concerns the PFP relief and patients' behavior after the conclusion of the therapeutic exercise program. The overall financial burden of sports-related injuries of the knees and lower legs has been estimated to be approximately 56 million euros annually (Finch, Kemp, and Clapperton, 2015). Therefore, it is essential to design and implement effective therapeutic exercise and prevention programs for the management and prevention of PFP. The main goal of these programs should be changing patients' habits in order to improve and, most importantly, maintain the level of well-being achieved through the program. The patients in our study confirmed that their behavior changed after enrolling in the therapeutic exercise program, which was reflected in positive changes in their physical, psychological and social well-being.
Until recently, studies exploring PFP have lacked the in-depth focus on patients' perspectives. The patients in our study expressed a clear need for an early diagnosis and, most of all, targeted therapeutic exercise programs. Future studies combining a qualitative and quantitative approach are needed to better understand the background and the impact of various therapeutic exercise programs on PFP. Combining these methodologies could provide a complete assessment of different rehabilitation approaches and their effect on patients' daily life.

Limitations
Some limitations of our study should be noted. First of all, our sample included only patients who participated in an 8-week targeted therapeutic exercise program. Therefore, it is not possible to draw conclusions about shorter or longer programs. Moreover, we included fourteen patients of all ages and backgrounds. Although this was done to ensure the heterogeneity of FG, it has been suggested by previous research that adolescents demonstrate specific characteristics which need to be considered in further studies. The use of online FG overcame some of the limitations of the classical FG, but also limited other aspects of communication, i.e. non-verbal communication (Bryman, 2015). Despite certain shortcomings, the study provides a greater understanding of perceptions of patients with PFP.

Conclusion
This was, to the best of our knowledge, the first study to explore the patients experience of a therapeutic exercise program in patients with PFP. Previous literature has focused primarily on kinematic and muscular impairments in PFP, overlooking patients' experience. Patients provided rich and detailed descriptions of their physical, psychological, and social well-being prior to the enrollment in the therapeutic exercise program. Our findings suggest that a targeted therapeutic exercise program is effective in reducing short-and long-term PFP and increasing overall well-being. However, further research is needed to explore the impact of different therapeutic exercise programs on the experience of PFP and toexamine the importance of maintaining self-motivation.

Disclosure statement
No potential conflict of interest was reported by the authors.