Lower extremity osteoarthritis is associated with lower health-related quality of life among retired professional footballers

ABSTRACT

Objective: The objective of the current study was to explore whether retired professional footballers suffering from lower extremity OA have a lower health-related quality of life than those without OA or current professional footballers.

Methods: An observational study based on a cross-sectional design by means of questionnaires was conducted. Participants were retired and current professional footballers recruited by the World Players’ Union (FIFPro). Information about lower extremity OA (clinically diagnosed by a medical professional) was gathered, while health-related quality of life (Global Physical Health and Global Mental Health scores) was assessed through a validated scale.

Results: A total of 396 retired and 361 current professional footballers were included in the analyses (response rate of 54%). The group of retired professional footballers was on average 36 years old, and they had competed in professional football for 11 years (retired for 5 years). The group of current professional footballers was on average 25 years old, and they had been active in professional football for 7 years. Within the group of retired professional footballers, prevalence of lower extremity OA was 33%. Both Global Physical Health and Global Mental Health scores among retired professional footballers with lower extremity OA were significantly lower than among retired players without OA and current players, but these scores were nearly similar to the norm for the general population (regardless the presence of OA or not).

Conclusions: Health-related quality of life among retired professional footballers with lower extremity OA was significantly lower than among retired players without OA and current players but nearly similar to the norm for the general population (regardless the presence of OA or not). A rational recommendation is that a support measure such as the After Career Consultation should be introduced among retired professional footballers in order to empower their sustainable health and quality of life, focussing especially on the prevention of the occurrence or worsening of lower extremity OA.

KEYWORDS:

• Professional football
• osteoarthritis
• quality of life
• epidemiology

Introduction

In professional football, the overall risk of injury was estimated to be 1000 times higher when compared to typical high-risk industrial occupations like in manufacturing, construction or in the service sector [1]. During their career, professional footballers are at risk to suffer from severe lower extremity injuries. In the UEFA Elite Club Injury Study during more than 10 seasons, an overall knee and ankle injury rate of 0.06 and 1.00 per 1000 h was found, respectively [2,3]. Among Australian professional footballers, a 5-year prospective cohort study showed that a typical squad with 25 players can expect up to 8 severe time-loss knee injuries and up to 3 severe time-loss ankle injuries every season [4]. These severe lower extremity injuries are likely to lead to sub-maximal performances but also to long-term health consequences, especially osteoarthritis (OA).

Expecting to become the world’s fourth leading cause of disability in 2020, OA is worldwide the most common rheumatic disease and leads to symptoms and activity limitations [5,6]. Asides from age, gender, obesity, and cumulative exposure to sport and occupational activities, severe joint injuries have been recognized as a risk factor for developing OA [5,7–9]. Therefore, retired professional footballers have an earlier onset and higher prevalence of lower extremity OA (hip, knee, ankle) than would be expected based on their age, especially those with a history of joint injury [10–14]. The prevalence of OA among retired players has shown to reach up to 13% for the hips, 80% for the knees and 17% for the ankles [10–14]. As recently emphasized, the adverse physical and mental impacts of OA on retired professional footballers should not be neglected: nearly 90% of those suffering from lower extremity OA reported to have moderate or severe joint pain and discomfort, while their condition was also associated with lower knee function as well as with symptoms of common mental disorders [15,16]. A rational assumption is that retired professional footballers suffering from lower extremity OA have a lower health-related quality of life than those without OA or than players being still active in professional football. Consequently, the objective of this study was twofold, namely: (1) to explore whether retired professional footballers suffering from lower extremity OA have a lower health-related quality of life than those without OA; and (2) to explore whether retired professional footballers suffering from lower extremity OA have a lower health-related quality of life than current professional footballers.

Methods

Design

An observational study based on a cross-sectional design by means of questionnaires was conducted, using the ‘Strengthening the Reporting of Observational Studies in Epidemiology’ statement in order to guarantee the quality of reporting [17]. Ethical approval for the study was provided by the Ethical Committee of the Yokohama City Sports Medical Center (17.003; Yokohama, Japan) and the Medical Ethics Review Committee of the Academic Medical Center (W16_366#16.431; Amsterdam, The Netherlands). The present study was conducted in accordance with the Declaration of Helsinki (2013).

Participants

The study population consisted of current and retired professional footballers recruited by the World Players’ Union (FIFPro). Inclusion criteria for the current players were: (1) being a current professional footballer; (2) being between 18 or older; (3) being male; (4) being able to read and comprehend texts fluently in English, French, or Spanish; (5) not suffering from lower extremity OA; (6) haven’t suffered from severe knee or ankle injuries (time-loss of 4 weeks or more) [18]; (7) haven’t undergone knee or ankle surgeries; (8) having access to their medical record or last team doctor. Inclusion criteria for the retired players were: (1) being a retired professional footballer; (2) being between 18 and 50 years; (3) being male; (4) being able to read and comprehend texts fluently in English, French, or Spanish; (5) having access to their medical record or last team doctor. In our study, the definition for a current or retired professional footballer was that he (1) trained (current) or had trained (retired) to improve football performances, (2) competed (current) or have competed (retired) in the highest or second highest national league, and (3) had (current) or have had (retired) training and competition as major activity (way of living) or focus of personal interest, devoting several hours in all or most of the days for these activities, and exceeding the time allocated to other types of professional or leisure activities. Sample size calculation with regard to our first research question indicated that 196 participants in each study group were needed (power of 80%, confidence interval of 95%; absolute precision of 5%) under the assumption of an anticipated population proportion of 20% [19]. Expecting a response rate of approximately 30% (based on previous studies in professional sports), we intended to reach at least 1300 participants (650 in each study group) [16,20].

Lower extremity OA

The presence of lower extremity OA, clinically diagnosed by a medical professional, was examined through a single question (‘Have you been diagnosed with OA in the hips, knees or ankles by a medical professional?’). In our study, OA was defined accordingly to the NICE criteria (adapted for age), namely as the damage of the joint’s cartilage that leads to activity-related joint pain and either no morning joint-related stiffness or morning stiffness that lasts no longer than 30 min (definition stated to participants) [21]. For this question, participants were requested to consult either their medical record or their last team doctor.

Health-related quality of life

The Patient-Reported Outcomes Measurement Information System Global Health (PROMIS-GH) was used to assess multiple domains related to health-related quality of life such as health, functioning, pain, social activities and fatigue [22]. The PROMIS-GH has been validated in several populations and languages among which English, French and Spanish (for detailed information, see www.nihpromis.org) [22]. Based on 10 items each measured on a 5-point scale (from 1 to 5) and subsequently converted, the Global Physical Health and Global Mental Health scores were calculated [22]. These subscale scores ranged from 0 to 100, with a higher score indicating better quality of life and a mean score of 50 indicating the norm for the general population [22].

Procedures

An electronic and/or paper anonymous questionnaire available in English, French and Spanish was compiled (LimeSurvey Professional), including the following descriptive variables (if applicable): age, body-height, body-weight, duration of professional football career, level of play, level of education, duration and nature of retirement, severely injured in knees and/or ankles during career (time-loss of 4 weeks or more), employment status [18]. Information about the study was sent per email to potential participants by FIFPro, procedures being blinded to the principal researcher for privacy reasons. If interested in the study, all participants gave their informed consent and completed the electronic questionnaire. Participants were asked complete the questionnaire within 2 weeks, reminders being sent after 2 and 4 weeks. The responses to the questionnaires were coded and depersonalized for reasons of privacy and confidentiality. Once completed, the electronic questionnaires were saved automatically on a secured electronic server that only the principal researcher could access. Players participated voluntarily in the study and did not receive any reward for their participation.

Statistical analyses

The statistical software IBM SPSS 24.0 for Windows was used to perform all data analyses. Analyses were conducted separately for current and retired professional footballers (with and without lower extremity OA). Descriptive analyses (mean, standard deviation, frequency and range) were performed for all variables included in the study. Prevalence of lower extremity OA was calculated in the group of retired professional footballers [19]. Prevalence (expressed as percentage) was calculated as the proportion of the number of participants with lower extremity OA relative to the total number of participants [19]. Descriptive analyses of health-related quality of life (Global Physical Health and Global Mental Health) were conducted, while comparisons between groups (retired players with OA vs. retired players without OA or current players) were made using Mann-Whitney test for independent samples [19].

Results

Participants

From a total of 2500 footballers contacted, a total of 1360 gave their written informed consent (response rate of 54%) to participate in the study. From the group of current players, 603 were excluded because of lower extremity OA, previous severe injuries or previous surgeries. Therefore, 396 retired and 361 current professional footballers were included in the analyses.

The group of retired professional footballers was on average 36 years old (SD = 6 years), and they had competed in professional football for 11 years on average (SD = 5 years). Retired professional footballers were retired from professional football for 5 years on average (SD = 4; 29% not voluntarily). About 90% of these retired players were employed in a salaried position. The group of current professional footballers was on average 25 years old (SD = 4), and had been active in professional football for 7 years on average (SD = 4). All characteristics of the retired (total; without OA; with OA) and current professional are presented in Table 1.

Table 1. Descriptive characteristics of retired and current professional footballers.

	Retired players (N = 396)			Current players
	Total	No OA	OA	(N = 361)
Age (in years; mean ± SD)	36 ± 6	36 ± 6	37 ± 5	25 ± 4
Height (in cm; mean ± SD)	181 ± 7	181 ± 7	181 ± 6	180 ± 8
Weight (in kg; mean ± SD)	82 ± 9	82 ± 9	83 ± 10	75 ± 9
Career duration (in years; mean ± SD)	11 ± 5	11 ± 5	12 ± 5	7 ± 4
Level of play (top league; %)	81	78	87	52
Educational level (%)
No schooling completed	0	0	2	1
Nursery/Elementary school	3	3	2	6
High school	28	31	23	48
Vocational/technical school	8	7	9	14
College, university or equivalent	61	59	64	31
Retirement duration (in years; mean ± SD)	5 ± 4	5 ± 4	6 ± 4
Forced retirement (%)	29	24	39
Employed (%)	89	87	91

N: number of participants; No OA: group without lower extremity osteoarthritis; OA: group with lower extremity osteoarthritis; SD: standard deviation; cm: centimetres; kg: kilograms; %: percentage

Lower extremity OA and health-related quality of life

Within the group of retired professional footballers, prevalence of lower extremity OA was 33% (mostly knee OA). As presented in Table 2, retired professional footballers with lower extremity OA suffered more often from severe injuries (91% vs. 70%) and surgeries (76% vs. 47%) during their career than those without OA. The mean Global Physical Health score among retired professional footballers with lower extremity OA was around 48, this score being significantly lower than among retired players without OA (Mann-Whitney test: U = 9923.50; Z = −6.11; p = 0.00) and current players (Mann-Whitney test: U = 13,297.00; Z = −6.32; p = 0.00), namely 53. The mean Global Mental Health score among retired professional footballers with lower extremity OA was around 50, while this score was significantly higher among retired players without OA (Mann-Whitney test: U = 13,421.00; Z = −2.56; p = 0.01) and current players (Mann-Whitney test: U = 18,654.50; Z = −2.13; p = 0.03), namely 52. Although both Global Physical Health and Global Mental Health scores among retired professional footballers with lower extremity OA were significantly lower than among retired players without OA and current players, these scores were nearly similar to the norm for the general population.

Table 2. Health-related quality of life among retired and current professional footballers.

		Retired players
		No OA	OA	Current players
Severe injuries (%)	No	30	9
	Yes	70	91
Surgeries (%)	No	53	24
	Yes	47	76
Global Physical Health*		52.7	47.6	52.6
Global Mental Health*		52.2	49.9	51.7

No OA: group without lower extremity osteoarthritis; OA: group with lower extremity osteoarthritis; %: percentage; *: a lower score indicate a lower level of global health

Discussion

The objective of this study was to explore whether retired professional footballers suffering from lower extremity OA have a lower health-related quality of life than those without OA or current professional footballers. The principal findings were that: (1) prevalence of lower extremity OA was 33% among retired professional footballers; (2) health-related quality of life (both Global Physical Health and Global Mental Health) among retired professional footballers with lower extremity OA was significantly lower than among retired players without OA and current players; and (3) health-related quality of life (both Global Physical Health and Global Mental Health) among retired professional footballers with lower extremity OA was nearly similar to the norm for the general population (regardless the presence of OA or not).

Perspective of our findings related to lower extremity OA

Within the group of retired professional footballers, the prevalence of lower extremity OA was 33%, being reported mostly in the knees (75%). This prevalence of lower extremity OA is similar to the available epidemiological information. Systematic literature reviews showed that the prevalence of lower extremity OA among retired professional footballers was 32%, ranging from 13% in the hips to 80% in the knees [11,13,23]. Worldwide, the current prevalence of OA has been reported to range from 10% to 25% in the male general population (from age 35 and above), while the prevalence of radiographic knee OA was reported to be 6% in male miners and 2% in male manual workers [11]. Consequently, it seems that the prevalence of lower extremity OA is higher among retired professional footballers. One rational explanation is that severe injuries and surgeries, especially in the knees and ankles, are common in professional football, and that those increase the likelihood to suffer from OA [5,7]. In our study, 70% of the retired players reported to have suffered from at least one severe knee or ankle injury during their career, and 50% reported to have undergone at least one joint surgery during their career.

Health-related quality of life

We found that retired professional footballers with lower extremity OA reported a lower health-related quality of life (both Global Physical Health and Global Mental Health) than among retired players without OA and current professional footballers, which was in line with our expectation. However, this health-related quality of life reported by retired professional footballers with lower extremity OA was nearly similar to the norm for the general population (regardless the presence of OA or not), which was not in line with our expectation. Potential explanations for that are difficult to formulate but one might assume that retired professional footballers with a mean age of 36 years being in the early years of their retirement, regardless to the presence of lower extremity OA, are experiencing a good quality of life, both physically and mentally. Even more, 9 out of 10 of the retired players were employed, which is likely to contribute significantly to their quality of life. On the other hand, recent scientific evidence has shown that the early years of transitioning out of professional football are likely to be associated with symptoms of common mental disorders [24,25]. These mental health problems, as well as physical problems such as lower extremity OA, do not seem to affect negatively the health-related quality of life of retired professional footballers. This was already suggested in one of our previous studies, in which 45% of the enrolled retired players reported that mental health problems did not affect negatively their quality of life after retirement [25]. Another potential explanation is that lower extremity OA, being symptomatic or not and leading or not to a decrease in joint function, is not likely to affect the quality of life of retired player because these players were used to cope during their football career with physical pain and discomfort. Despite our findings, scientific studies have shown that lower extremity OA among retired professional footballers is associated with a lower level of physical knee function [10,13,15]. Therefore, the question, whether a specific management of retiring professional footballers is warranted, can be unequivocally answered, namely yes.

The management of retiring professional footballers

With regard to the physical (and mental) health problems likely to occur while transitioning out of professional football, for instance lower extremity OA, players should be enabled to apply to and rely on a support measure being specifically developed for their needs and particular situation. However, both current and retired professional footballers have mentioned that such a support measure for their retirement years was not available yet [25,26]. Therefore, FIFPro has developed for retired professional footballers the After Career Consultation in order to empower their sustainable physical, mental and social health, and their quality of life [27,28]. According to the view and needs of both current and retired professional footballers, the After Career Consultation focusses on several relevant domains, especially (1) detraining from professional football, (2) prevention of the occurrence or worsening of lower extremity OA, (3) promotion of healthy life style, and (4) preventing mental and cognitive health problems [27,28]. Through this After Career Consultation, retired professional footballers (1) received information (leaflets) to raise their awareness about the transitioning period and its potential related risks, (2) undergo a medical examination (60 min) related to all major body systems that might lead to advices for the upcoming period, and (3) are monitored/coached during 3–6 months (if necessary) [27,28]. With regard to lower extremity OA, this After Career Consultation aims to promote the prevention of the occurrence or worsening of lower extremity OA and provides retired professional footballers with relevant basic information about risk and worsening factors, treatments, recommended exercise programs, sport activities, occupational activities, and life style [28]. The relevancy, suitability, satisfaction, and added value of the After Career Consultation were positively evaluated by retired professional footballers during a pilot-study in The Netherlands, while such a concept is nothing less than a duty of care that should be funded and implemented by all stakeholders in professional football [29].

Methodological reflection

In our study, the recruitment procedures were blinded to the research team for privacy and confidentiality reasons. Therefore, non-response analysis could not be conducted. Also, as in any scientific study, participants were free to be included in the study and thus self-selected. This might have led to selection bias as participants with more interest with OA might have been more likely to participate. However, with regard to the response rate achieved in our study (54%) and the enrolment of 396 retired and 361 current professional footballers, we are confident that potential bias was avoided and that the external validity of our findings is not limited.

Health-related quality of life was self-reported and assessed with the PROMIS-GH. The authors are well aware that other self-report instruments or scales are available to assess such a construct. However, the PROMIS-GH fulfilled the necessary conditions to increase the feasibility and quality of our study, namely: (1) short thus time efficient; (2) valid in English, French and Spanish; (3) covering physical- and mental-related quality of life. Even more, Patient-Reported Outcome Measures as validated instruments that reflect the patient’s perspective about their health status, have been in the past few years exponentially applied to assess the aspects that matter most to patients and to enable important clinical questions to be answered [30].

Clinical lower extremity OA diagnosed by a medical professional was reported by the participants. The ideal measurement of OA would have been the clinical examination of all participants, which is barely feasible in large international research. Nevertheless, we strived to guarantee the validity of the data collected by stating clearly to all participants the definition of lower extremity OA in our study and requesting them to consult either their medical record or last team doctor with regard to OA. In order to precisely appreciate the validity of the data collected, the concurrent validity of self-reported clinical lower OA with radiological OA might be explored in the future.

Conclusions

Prevalence of lower extremity OA among retired professional footballers was 33%. Health-related quality of life (both Global Physical Health and Global Mental Health) among retired professional footballers with lower extremity OA was significantly lower than among retired players without OA and current players but nearly similar to the norm for the general population (regardless the presence of OA or not). A rational recommendation is that a support measure such as the After Career Consultation should be introduced among retired professional footballers in order to empower their sustainable health and quality of life, focusing especially on the prevention of the occurrence or worsening of lower extremity OA.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. Peer reviewers on this manuscript have no relevant financial relationships or otherwise to disclose.

Acknowledgments

The authors are grateful to all retired and current professional footballers who participated in the study.

Additional information

Funding

None.