Osteoarthritis of the hip and knee in former male professional soccer players

Does Playing Football (Soccer) Really Increase the Risk of Knee Osteoarthritis? A Systematic Review and Meta-analysis

OBJECTIVE: To evaluate the relationship between football (soccer) participation and tibiofemoral knee osteoarthritis (OA), considering the influence of competitive level and previous knee injuries. DESIGN: Etiology systematic review with meta-analysis. LITERATURE SEARCH: PubMed, Embase, AMED, and Cochrane were searched for relevant publications. STUDY SELECTION CRITERIA: Studies of football players that included a control group consisting of mainly sedentary nonfootball players, and the relationship of knee OA, were considered. The studies had to report radiographically verified knee OA and specify football activity. DATA SYNTHESIS: Eleven studies, involving 1805 football players and 4022 control individuals were included. Subgroups consisting of data regarding level of play and previous injuries were also synthesized. RESULTS: The overall prevalence of knee OA among football players was increased among professional and recreational players, compared with controls. When knee injuries were excluded, there was no difference in knee OA between football players and controls (OR = 1.25; 95% CI: 0.61, 2.54). Football players with a previous knee injury had a greater risk of knee OA when compared with football players with no history of previous knee injury (OR = 4.16; 95% CI: 1.97, 8.77). CONCLUSION: Football players were at increased risk of knee OA. However, after excluding participants with a history of previous knee injury, there were no differences in knee OA between football players and controls. Previous knee injury was important for developing knee OA. Playing football, in the absence of major knee injuries, did not increase the risk of knee OA. J Orthop Sports Phys Ther 2024;54(5):1-12. Epub 26 February 2024. doi:10.2519/jospt.2024.12029.

Strength Training Is Associated With Less Knee Osteoarthritis: Data From the Osteoarthritis Initiative

OBJECTIVE

We aimed to evaluate the relationship of a history of strength training with symptomatic and structural outcomes of knee osteoarthritis (OA).

METHODS

This study was a retrospective, cross-sectional study within the Osteoarthritis Initiative (OAI), a multicenter prospective longitudinal observational study. Data were collected at four OAI clinical sites: Memorial Hospital of Rhode Island, the Ohio State University, the University of Pittsburgh, and the University of Maryland/Johns Hopkins. The study included 2,607 participants with complete data on strength training, knee pain, and radiographic evidence of knee OA (male, 44.2%; mean ± SD age 64.3 ± 9.0 years; mean ± SD body mass index 28.5 ± 4.9 kg/m2 ). We used a self-administered questionnaire at the 96-month OAI visit to evaluate the exposure of strength training participation during four time periods throughout a participant's lifetime (ages 12-18, 19-34, 35-49, and ≥50 years old). The outcomes (dependent variables) were radiographic OA (ROA), symptomatic radiographic OA (SOA), and frequent knee pain.

RESULTS

The fully adjusted odds ratios (95% confidence interval) for frequent knee pain, ROA, and SOA among those who participated in strength training any time in their lives were 0.82 (0.68-0.97), 0.83 (0.70-0.99), and 0.77 (0.63-0.94), respectively. Findings were similar when looking at the specific age ranges.

CONCLUSION

Strength training is beneficial for future knee health, counteracting long-held assumptions that strength training has adverse effects.

Prevalence of hip femoroacetabular impingement deformities in high-level (La Liga) male professional football players

BACKGROUND

Femoroacetabular impingement (FAI) is considered one of the main causes of hip osteoarthritis in young adults, especially in athletes. In recent years, morphological changes in FAI in the hip have been linked to early and intense sports participation, but studying top-level athlete samples is not easy. This paper presents the prevalence of FAI radiological markers in 120 active white male professional football players in the Spanish First Division League (La Liga) and compares the morphological changes with those of a control group of healthy individuals without significant sport activity.

METHODS

The precontract medical evaluation hip X-rays of 120 white male professional football players from four different First Division Spanish football teams were prospectively filed and retrospectively reviewed by a dedicated skeletal radiologist. The footballers' hip X-rays were compared with those of a control group of 80 healthy individuals (age-sex matched) without significant sport activity (obtained from routine work medical checks).

RESULTS

The femoral head-neck deformity associated with the Cam type of femoroacetabular impingement was observed in 61.6% of professional football players and only in 11.6% of the control group (p <0.01). The presence of "herniation pit" (11.6%) and os acetabuli (13.3%) also reached statistical significance in the professional football players group. In the other analyzed parameters, no statistically significant differences between the groups were observed.

CONCLUSIONS

White professional top-level football players have an increased incidence of abnormal lateral epiphyseal extension ("pistol grip deformity"), os acetabuli and herniation pits.

The association between lateral hip muscle size/intramuscular fat infiltration and hip strength in active young adults with long standing hip/groin pain

OBJECTIVES

To investigate associations between lateral hip muscle size/intramuscular fat infiltration (MFI) and hip strength in active young adults with longstanding hip/groin pain.

DESIGN

Cross-sectional study.

SETTING

University/Clinical.

PARTICIPANTS

Sub-elite soccer and Australian Football players (n = 180; 37 female) with long standing hip/groin pain.

MAIN OUTCOME MEASURES

Muscle size (volume) and MFI of gluteus maximus, medius, and minimis, and tensor fascia latae (TFL) were assessed using magnetic resonance imaging. Isometric hip strength was measured with handheld dynamometry. Associations between muscle size/MFI were assessed using linear regression models, adjusted for body mass index and age, with sex-specific interactions.

RESULTS

Positive associations were identified between lateral hip muscle volume and hip muscle strength, particularly for gluteus maximus and gluteus minimus volume. For all muscles, hip abduction was associated with an increase in strength by up to 0.69 N (R2 ranging from 0.29 to 0.39). These relationships were consistent across sexes with no sex interactions observed. No associations were found between MFI and strength measures.

CONCLUSION

Greater lateral hip muscle volumes are associated with greater hip strength in active young adults with long standing hip/groin pain, irrespective of sex. Gluteus maximus and minimus volume showed the most consistent relationships with hip strength across multiple directions.

Intra-articular injections in sport-active patients with degenerative cartilage lesions or osteoarthritis of the knee: a systematic review

PURPOSE

The aim of this systematic review was to analyse the available clinical evidence on intra-articular knee injections for the treatment of degenerative cartilage lesions and osteoarthritis (OA) in sport-active patients.

METHODS

A literature search was performed in July 2023 according to the PRISMA guidelines on three electronic databases (PubMed, Cochrane, Web of Science). Studies addressing intra-articular injections for degenerative knee cartilage lesions or knee OA in sport-active patients were included. The Downs and Black's "checklist for measuring quality" was used to evaluate risk of bias and quality of the included studies.

RESULTS

Only 10 clinical studies for a total of 296 sport-active patients were included, with a publication trend increasing over time. The studies were 9 case series and 1 RCT; 7 studies focused on hyaluronic acid (HA), 2 studies focused on platelet-rich plasma (PRP), while 1 study compared HA and PRP. Overall, safety and positive clinical findings were for both HA and PRP, although not always with satisfactory results in terms of return to sport. The Downs and Black evaluation showed an overall poor quality of the included studies, with an average score of 21.1 points (range 19-25).

CONCLUSIONS

The available clinical evidence is still limited, with only a few studies published and an overall low-quality of evidence, suggesting a potential role of HA and PRP injections to treat these patients. However, further high-level trials are needed to confirm the real benefits of these treatments for the management of sport-active patients affected by degenerative cartilage lesions or OA of the knee.

Determination of the Prevalence of Knee and Hip Clinical Osteoarthritis in the Active Professional Male Footballer and Its Association with Pain, Function, Injury and Surgery

OBJECTIVE

To comment on and explore (1) the prevalence of clinical knee and hip osteoarthritis (OA); (2) the association between pain or function and clinical knee or hip OA; (3) the association between injury or surgery and clinical knee or hip OA.

METHODS

Participants were recruited from FIFPRO members. A total of 101 footballers consented to answer (1) a developed questionnaire, (2) patient-reported outcome measures, and (3) be evaluated by their team physician for clinical knee or hip OA.

RESULTS

Of the 53% evaluated for clinical knee and hip OA, a prevalence of 9.43% and 7.55% of knee and hip OA, respectively, was found. There was a significant and strong association between knee (p = 0.033; Cramers v Value = 0.523) and hip pain (p = 0.005; Cramers v Value = 0.602) and clinical OA. A significant association existed between Hip dysfunction and Osteoarthritis Outcome short form Scores and clinical OA of the hip (p = 0.036). The odds of clinical knee OA were 1.5 and 4.5 times more after one or more injuries or surgeries, respectively. There was no association between playing position and clinical OA.

CONCLUSION

There is a low prevalence of a clinical knee or hip OA in the active professional male footballer. Pain may be a valid symptom to predict or monitor knee or hip OA. Validated assessment tools should be utilised to identify a negative effect on function. The odds of developing clinical OA in the knee with the number of injuries or surgeries. The hip presents with earlier clinical signs of OA compared to the knee.

Risk of total hip arthroplasty after elite sport: linking 3304 former world-class athletes with the Norwegian Arthroplasty Register

OBJECTIVES

At present, there is no cure for osteoarthritis (OA), but severe hip joint degeneration can require total hip arthroplasty (THA). The literature on OA after elite sport is limited. We hypothesise that elite athletic activity increases the risk of receiving a THA later in life.

METHODS

We linked a cohort of former Norwegian world-class athletes (1402 females and 1902 males, active 1936-2006) to the Norwegian Arthroplasty Register (THA performed 1987-2020). We used standardised incidence ratio (SIR), one-minus Kaplan-Meier and relative Cox regression (relative HR, RHR), with 95% CIs, and funnel plots at age 75, to assess THA risk for different sport disciplines, joint impact categories of sport disciplines and sex. The risk of THA for the corresponding general Norwegian population was used as reference.

RESULTS

We found an overall increased risk for THA for the former elite athletes (SIR 2.11, 95% CI 1.82 to 2.40) at age 75 years, compared with the general population. THA risk at age 75 years was 11.6% for female athletes and 8.3% for male athletes. SIR was 1.90 (95% CI 1.49 to 2.31) for female and 2.28 (95% CI 1.87 to 2.70) for male athletes. Among males, high joint impact sport disciplines were associated with increased risk compared with low-impact sport disciplines (RHR 1.81, 95% CI 1.06 to 3.08, p=0.029).

CONCLUSION

Having been an elite athlete was associated with a doubling of THA risk compared with the general population for both sexes. High joint impact sport disciplines were associated with subsequent THA for male athletes.

Osteoarthritis Risks and Sports: An Evidence-based Systematic Review

PURPOSE

Regular sports activities are associated with multiple physical and psychological health benefits. However, sports also may lead to injuries and the development of osteoarthritis (OA). This systematic review investigated the association between sports activity, sports type, and the risk of developing OA.

METHODS

A systematic review was performed by assessing studies that have investigated the risk of OA development in sports. Data extracted included general information, study design, number of participants, related body mass index, sports type, and assessment of OA. The methodological quality of the studies was assessed using the Newcastle-Ottawa Scale.

RESULTS

A total of 63 studies were included in this systematic review. The overall Newcastle-Ottawa Scale score was 6.46±1.44 demonstrating a good methodological quality of the articles included in the present study. A total of 628,036 participants were included, with a mean follow-up of 8.0±8.4 years. The mean age of the included athletes was 45.6±15.8, with a mean body mass index of 24.9±2.3 kg/m 2 .

CONCLUSION

Football and soccer players seem to be at higher risk for the development of OA, although the injury status of the joint should be considered when assessing the risk of OA. High equipment weight and increased injury risk also put military personnel at a higher risk of OA, although elite dancing leads to more hip labral tears. Femoroacetabular impingement was also often diagnosed in ice-hockey players and ballet dancers.

Prior Injury, Health-Related Quality of Life, Disablement, and Physical Activity in Former Women's Soccer Players

CONTEXT

Former collegiate athletes may be at risk for negative health outcomes such as lower health-related quality of life (HRQoL), greater disablement, and lower lifetime physical activity (PA) participation. A history of severe sport injury may play a role in these outcomes.

OBJECTIVE

To assess the role of prior sport injury in self-reported HRQoL, levels of disablement, and PA behaviors of former National Collegiate Athletic Association Division I women's soccer players.

DESIGN

Cross-sectional study.

SETTING

Online survey.

PATIENTS OR OTHER PARTICIPANTS

Former Division I women's soccer players (n = 382, age = 36.41 ± 7.76 years) provided demographics and injury history and completed the Patient-Reported Outcomes Measurement Information System (HRQoL), the Disablement in the Physically Active Scale (disablement), and the Godin Leisure Time Physical Activity Questionnaire (PA).

MAIN OUTCOME MEASURE(S)

The dependent variables were the physical and mental component summary scores for HRQoL and disablement and the frequency of moderate-to-vigorous PA. Means, SDs, and correlations among the main outcome variables were examined for those who reported a severe injury (n = 261) and those who did not (n = 121). To address our primary aim, we conducted multiple regression analyses to predict HRQoL, disablement, and PA based on a history of severe injury, accounting for age.

RESULTS

Having a severe injury significantly predicted worse physical HRQoL and worse physical disablement. Severe injury predicted a >2-point decrease and 5-point increase on the respective scales. Injury status did not predict mental HRQoL, mental disablement, or PA.

CONCLUSIONS

Most participants reported sustaining a prior severe soccer-related injury, which may have had a negative long-term effect on health outcomes for former women's soccer players. Athletic trainers should be aware of the risk for decreased HRQoL and increased disablement with injury and encourage continued monitoring of relevant patient-reported outcomes.

Arthroscopic Management of Femoroacetabular Impingement in Adolescents: A Systematic Review

BACKGROUND

Femoroacetabular impingement (FAI) is highly prevalent in adolescent athletes. There has been an increasing trend for arthroscopic surgery for FAI, and the results of several clinical studies on outcome after arthroscopic surgery for FAI are available.

PURPOSE

To conduct a systematic review to investigate the role of arthroscopic management for FAI in adolescents.

STUDY DESIGN

Systematic review.

METHODS

This systematic review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. In August 2020, PubMed, Scopus, Google Scholar, and EMBASE were accessed. All clinical trials concerning the arthroscopic treatment for adolescents with FAI were identified. Only studies on patients aged less than 18 years at the time of surgery reporting data over a minimum follow-up of 12 months were considered.

RESULTS

Data from 406 adolescents (470 procedures; mean age at surgery, 15.9 years; mean follow-up, 30.4 months) with FAI were retrieved. At a mean of 28.0 months of follow-up, 94% of the adolescents had already returned to sport. All the scores of interest were improved at the final follow-up: visual analog scale (P = .01), modified Harris Hip Score (P < .0001), Non-Arthritic Hip Score (P = .03), Hip Outcome Score-Activities of Daily Living (P = .01), Hip Outcome Score-Sport-Specific Subscale (P < .0001), and Tegner score (P < .0001). Complications occurred in 1.1% (5/470) of procedures, and revision arthroscopy was performed in 4.7% (22/470) of procedures.

CONCLUSION

Arthroscopic surgery in adolescents with FAI achieves excellent outcomes and a high rate of return to sport, with rates of complication and revision surgery of 1% and 5%, respectively.

The Risk of Knee Osteoarthritis in Professional Soccer Players

BACKGROUND

We address the question whether professional soccer players with and without macroinjury of the knee joint are at an elevated risk for knee osteoarthritis.

METHODS

A systematic review with meta-analyses was conducted. The study protocol was prospectively registered (registration number CRD42019137139). The MEDLINE, EMBASE, and Web of Science databases were searched for relevant publications; in addition, forward searching was performed, and the listed references were considered. All steps of the process were undertaken independently by two reviewers, and any discordances were resolved by consensus. For all publications whose full text was included, the methods used were critically evaluated. The quality of the evidence was judged using the GRADE criteria.

RESULTS

The pooled odds ratio for objectively ascertained osteoarthrosis of the knee was 2.25 (95% confidence interval [1.41-3.61], I² = 71%). When only radiologically ascertained knee osteoarthrosis was considered, the odds ratio was 3.98 [1.34; 11.83], I² = 58%). The pooled risk estimator in studies in which knee joint macroinjury was excluded was 2.81 ([1.25; 6.32], I² = 71%).

CONCLUSION

A marked association was found between soccer playing and knee osteoarthritis in male professional soccer players. For female professional soccer players, the risk of knee osteoarthritis could not be assessed because of the lack of data. Knee injuries seem to play an important role in the development of knee osteoarthritis in professional soccer players.

Clinical Hip Osteoarthritis in Current and Former Professional Footballers and Its Effect on Hip Function and Quality of Life

The objective of the study was to establish the prevalence of clinical hip osteoarthritis in current and former professional footballers and to explore its consequences on hip function and health-related quality of life (HRQoL). A cross-sectional study by means of questionnaire was conducted among current and former professional footballers fulfilling the following inclusion criteria: (1) male (2) active or retired professional footballer (3) member of FIFPRO (Football Players Worldwide) (4) between 18 and 50 years old (5) could read and understand texts in French, Spanish, or English. Controls (matched for: gender, age, body weight and height) were also recruited. The main outcome measures were clinical hip osteoarthritis, hip function and HRQoL. Questionnaires were sent to 2,500 members of which 1,401 participated (1,000 current and 401 former professional footballers). Fifty-two controls were recruited. Prevalence of hip osteoarthritis was 2% among current and 8% among former professional footballers. Hip function was significantly (p ≤ 0.001) lower in both types of footballers with hip osteoarthritis than in footballers without hip osteoarthritis and controls. Current and former professional footballers with hip osteoarthritis reported significantly lower physical health scores (p = 0.032, p = 0.002) than those without. Hip osteoarthritis led to a significantly lower score in the physical (p = 0.004) and mental (p = 0.014) component of HRQoL in former footballers compared to the controls, while in current footballers only the physical component was significantly (p = 0.012) lower compared to the controls. Hip osteoarthritis has a higher prevalence in former than in current professional footballers and impacts hip function and HRQoL negatively.

Football-related injuries are the major reason for the career end of professional male football players

PURPOSE

Little is known about the consequences of injuries on professional male football players' career and retirement period. The aim of this study is to investigate the impact of injuries that male professional football players endure during their career, reasons for the end of their career and the post-career phase of retirement.

METHODS

In a retrospective cross-sectional cohort study, retired male professional football players of the German Bundesliga were investigated by a standardised questionnaire to analyse the history of injuries sustained during their professional football career, the reasons for ending their career, their current health status and their suggestions for future prevention strategies.

RESULTS

Most of the 116 analysed players (n = 73 (62.9%)) stated an injury as the reason for ending their professional career. Relevant injuries were mainly located in the lower extremities (n = 587 (61.3%)) with a focus on the knee (p < 0.001) and ankle (p < 0.001). A significant majority of the participants who had retired due to injury described degenerative symptoms, such as pain or instability, and were diagnosed with osteoarthritis after retirement (p < 0.001). These players had also often been affected by symptoms of depression during their career, which had decreased significantly after retirement. Moreover, players who had not retired due to injury had significantly better overall health status and quality of life after retirement.

CONCLUSION

Football-related injuries have a significant impact on the career end of professional male football players and their health status after retirement. Future prevention strategies need to particularly address injuries to the knees and ankles and to implement measures for preventing osteoarthritis after retirement.

LEVEL OF EVIDENCE

Level III.

Retirement of professional soccer players - A systematic review from social sciences perspectives

Retiring professional athletes face multifaceted changes and potential issues of adjustment, occupational development, and well-being, which raises concerns around the world. The study systematically reviewed the available research investigating professional soccer players' sport retirement from social sciences perspectives. The literature search in electronic databases and a "snowballing" procedure yielded 17 eligible studies investigating > 2,200 retired professional soccer players. The review followed the PRISMA statement. Nine studies focused on an early transition phase to retirement period; four studies investigated later periods of ten years or longer after retirement. Around half of the players reported involuntary retirement, often associated with declining performance and/or injury. Studies suggest issues of adjustment and mental health during early years after retirement, while psychological issues had apparently declined around 1-2 decades after retirement. However, available studies had notable limitations including lack of evidenced representative samples, report of measures' reliability, and control for confounders. Furthermore, while theoretical models emphasise a holistic perspective, quantitative research often took a narrow rather than holistic perspective. In summary, available knowledge is fraught with some uncertainty regarding reliability and representativeness of the population of retired professional soccer players. We offer future directions to advance the development of a theory of sport retirement.

Every second retired elite female football player has MRI evidence of knee osteoarthritis before age 50 years: a cross-sectional study of clinical and MRI outcomes

PURPOSE

To assess knee health in retired female football players, using magnetic resonance imaging (MRI) and self-report. The focus of analysis were degenerative changes of the tibiofemoral joint, and their relationship to osteoarthritis symptoms and previous knee injury.

METHODS

Forty-nine retired elite, female football players (98 knees) aged 37 years on average participated. Tibiofemoral cartilage and meniscus status of both knees were evaluated using MRI and graded according to modified Outerbridge and Stoller classifications, respectively. Symptoms were assessed through a standardised questionnaire (Knee Osteoarthritis Outcome Score: KOOS). Knee injury history was recorded via a semi-structured interview. To investigate how injury variables relate to outcomes, binary logistic regression models were used and reported with odds ratios (OR).

RESULTS

Fifty-one per cent of players (n = 25) fulfilled the MRI criterion for knee osteoarthritis, 69.4% (n = 34) had substantial meniscal loss and 59.6% (n = 28) reported substantial clinical symptoms. Chondral- and meniscal loss were associated with significantly lower scores on three of five KOOS subscales (p < .05). Both chondral and meniscal loss were significantly predicted by previous traumatic knee injury (OR = 4.6, OR = 2.6), the injury affecting the non-striking leg (OR = 8.6, OR = 10.6) and type of injury; participants with combined ACL/meniscus injuries had the highest risk for substantial chondral and meniscal loss (OR = 14.8, OR = 9.5). Chondral loss was significantly predicted by isolated meniscus injury treated with partial meniscectomy (OR = 5.4), but not by isolated reconstructed ACL injury. Clinical symptoms were only significantly predicted by previous traumatic knee injury (OR = 5.1).

CONCLUSIONS

Serious degenerative changes were found in a high number of retired female football players' knees 10 years after their career. Meniscal integrity is key for knee osteoarthritis outcomes in young adults, and thus, its preservation should be a priority.

One-staged combined hip and knee arthroplasty: retrospective comparative study at mid-term follow-up

Background

To date, few knowledge is available about safety and effectiveness of one-staged combined hip and knee arthroplasty. The aim of our study was to evaluate, in a comparative fashion, complications and outcomes in patients who underwent one-staged hip and knee arthroplasty.

Methods

Forty-two patients were enrolled and allocated into two groups of 21 patients each: one-staged hip and knee arthroplasty (group A) and two-staged hip and knee arthroplasty (group B). The follow-up averaged 50.2 months. Postoperative complications and implant survivorship were assessed prospectively. Outcomes were evaluated with Harris Hip score (HSS), Western Ontario Mc-Ministry score for the hip (h-WOMAC), Knee Society score (KSS), and Western Ontario Mc-Ministry knee score (k-WOMAC). Hip and knee range of motion (ROM) were measured both preoperatively and at the last follow-up.

Results

Two (9.5%) patients in group A and three (14.3%) patients in group B developed complications (P = 0.8). Although a significant decrease in postoperative haemoglobin (Hgb) values was found in group A patients during the hospital stay, no differences in blood transfusions were found (P = 0.8). No significant differences were found comparing clinical-functional outcomes between the two groups, while a significant reduction of hospital length of stay was shown in group A patients.

Conclusions

One-staged combined hip and knee arthroplasty could be considered in patients with co-existing severe hip and knee osteoarthritis, providing similar complications and mid-term outcomes of two-staged procedures. However, the reproducibility safety and reliability of these procedures should be confirmed in prospective comparative randomised trials with more numerous patients.

Trial registration

Retrospectively registered

Post-football Gonathrosis: Injuries and Surgeries are A Risk

Football is one of the most popular sports in the world. Many studies have shown there is a high incidence of gonarthrosis in football players. The reason for this increase is said to be injuries to the meniscus, the anterior cruciate ligament (ACL) and the resulting surgeries. The incidence is significantly increased in players with knee injuries. The knee is also the most commonly injured site in football and the most common cause of surgery in football players. Together these injuries, particularly of the ACL or meniscus and the resulting surgeries, increase the risk of developing gonarthrosis in post-football years.

How far have biological therapies come in regenerative sports medicine?

INTRODUCTION

Regular engagement in sports produces many health benefits, but also exposes to increased injury risk. The quality of medical care available is crucial not only for sports trauma but also to avoid overuse syndromes and post-traumatic degenerative conditions.

AREAS COVERED

We provide background information on some clinical needs in sport injuries and describe the main families of biological products used in clinical practice. We also discuss limitations of the current clinical experience.

EXPERT OPINION

Sport and exercise impairment affects different segments of the population with different needs. The exceptional demands of elite athletes and subsequent media coverage have created hype around regenerative therapies. Statistical evidence, whether weak (cell products) or moderate (PRPs), is not enough to drive medical decisions because of the heterogeneity of the biological products available and their application procedures. Moreover, the specific needs of the different segments of the population along with the available clinical evidence for each musculoskeletal condition should be considered in the decision-making process. There is urgent need to develop regenerative protocols combined with post-intervention rehabilitation, and gather meaningful clinical data on the safety and efficacy of these interventions in the different populations segments.

Bowlegs and Intensive Football Training in Children and Adolescents

BACKGROUND

In many countries around the world, football (association football, or "soccer" predominantly in North America) is the sport most commonly played by children and adolescents. It is widely thought that football players are more likely to develop genu varum (bowlegs); an association with knee arthritis also seems likely. The goals of this systematic review and meta-analysis are to provide an overview of the available evidence on genu varum after intensive soccer training in childhood and adolescence, and to discuss the possible pathogenetic mechanisms.

METHODS

We systematically searched the PubMed, Medline, Embase, and Coch- rane Library databases for studies of the relation between leg axis development and intensive football playing during the growing years.

RESULTS

Controlled studies employing the intercondylar distance (ICD) as the target variable were evaluated in a meta-analysis, with the mean difference as a measure of effect strength. This meta-analysis included 3 studies with a total of 1344 football players and 1277 control individuals. All three studies individually showed a signifi- cant difference in the mean ICD values of the two groups. The pooled effect esti- mator for the mean difference was 1.50 cm (95% confidence interval [0.53; 2.46]). Two further studies that could not be included in the meta-analysis had similar con- clusions. Asymmetrical, varus muscle forces and predominantly varus stress on the osseous growth plates neighboring the knee joint, especially during the prepubertal growth spurt, seem to be the cause of this phenomenon.

CONCLUSION

Intensive soccer playing during the growing years can promote the devel- opment of bowlegs (genu varum) and, in turn, increase the risk of knee arthritis. Phy- sicians should inform young athletes and their parents of this if asked to advise about the choice of soccer as a sport for intensive training. It cannot be concluded, however, that football predisposes to bowlegs when played merely as a leisure activity.