Asymptomatic lumbar spine pathology was found in 83% of participants within a cohort of elite male academy footballers. The pathologies detected varied with disc degeneration being the most prevalent abnormality seen. Both goalkeepers included in the study had the most extensive disc degeneration (at L4/L5, L5/S1 respectively), and this may be reflective of their specific positional demands (e.g. diving, repetitive lumbar spine extension). Though more research into goalkeepers is needed to confirm this observed trend.
Clinical implications of findings
These findings highlight the importance of interpreting MRI findings in elite male academy footballers in the context of the clinical signs and symptoms. Team doctors should exercise caution when requesting MRI lumbar spine imaging unless there is a clear clinical indication, and thought has been given as to how to deal with clinically insignificant findings. This study also demonstrates the potential utility of MRI 3D VIBE sequencing to diagnose and assess healing of pars injuries in elite footballers and could negate the need to expose players to ionising radiation (e.g., CT).
Are these findings normal in young athletes?
These findings are consistent with an emerging body of research which has identified that both symptomatic and asymptomatic lumbar spine pathology is common amongst young athletes and the active population.18 Disc degeneration amongst this cohort of professional footballers was the most prevalent abnormality seen (39%), and was marginally higher than that seen in non-athletes of a similar age profile (31–37%),19,20 Other youth sport athletes have shown higher rates of disc degeneration, e.g. tennis players (62%)4 and elite gymnasts (75%).20 The prevalence of facet joint arthropathy (6%) was considerably lower than that seen amongst tennis players (90%)4, but mirrored findings in the general population for those aged under 30 years of age (4–9%).19 No data from the age-matched general population is, to the authors’ knowledge, available for comparison. The prevalence of asymptomatic pars injury, although reasonably high (22%), was less than that seen in diving (35%) or cricket (32%) where repetitive spinal flexion, rotation and hyperextension actions increase the risk of pars injury.21 It therefore seems that partaking in high volumes of highly specialized sport from a young age increases the risk of both asymptomatic and symptomatic lumbar spine pathologies. The risk of these pathologies appears to be dependent on the sport and its sport-specific demands on the lumbar spine (e.g., repeated spinal rotation, lumbar flexion or rapid sprint decelerations).
Should we be concerned about the findings?
Four asymptomatic participants were identified to have pars fractures on MRI. There was no clear trend between the player’s dominant foot and the side on which the pars fracture presented, and their playing position did not appear to be contributory. Detailed clinical examination may have elicited positive findings in these cases, however, the absence of symptoms may also be explained by different pain coping mechanisms among elite athletes, the possibility that the players may be truly asymptomatic or that the imaging changes precede the symptoms as has been shown in cricket.9,22 One player had endplate concavities at L2, L3 and L5 which can be suggestive of sickle cell disease.23 In accordance with the pre-established protocol for managing incidental findings, a sickle screen blood test was performed which was negative.
It is unknown whether these findings are unique to the team assessed or a common trend in football. Until larger studies identify prevalence values, these findings of concern highlight the importance of regularly screening youth academy footballers despite being asymptomatic, similar to standards already in place in sports such as cricket.9 Considering the burden of these injuries in Academy footballers, such screening may prove beneficial to the long-term health and performance of players.2
As asymptomatic lumbar spine pathologies have been shown to be common when partaking in high volumes of a highly specialised sport from a young age, it is important to not just screen but also aim to minimise the risk of these pathologies. The football physician should ensure early identification of symptoms to enable appropriate strength training and load management in order to prevent progression to a significant time-loss injury. With specific reference to preventing pars stress fractures, other plausible interventions may include Vitamin D supplementation and ensuring adequate energy availability to meet training demands.25,26 This is particularly important as, prolonged absence through injury leads to significant ‘lost development time’ for academy players which can hinder career progression.27
Strengths and limitations
This is the first study to describe the MRI lumbar spine findings of asymptomatic elite male adolescent footballers. A rigorous study design protocol was adhered to using the STROBE checklist. Novel and emerging imaging techniques (e.g., MRI 3D VIBE) were employed to describe common injuries (e.g., pars).
The most obvious limitation to this study is the small sample size; although this is comparable to other studies investigating elite sporting populations. Our study may have benefitted from including more extensive baseline data such as height, weight, peak height velocity, ethnicity and Vitamin D levels but with the low sample size any investigated associations would have been exploratory and limited. Future studies should look to include a larger sample size, from a variety of different clubs to more accurately identify prevalence and to explore the relationship between clinical examination findings and imaging results. Long-term follow-up of these athletes over the course of their career may also provide insight into the specific effects of professional football on spine health, as well as helping to predict which imaging findings may precede symptom-onset.