This is the first report of injury surveillance of elite para-athletes with limb deficiency. Irrespective of location and level of limb deficiency, injuries to the glenohumeral joint were the most frequently reported in this population of elite athletes with limb deficiency. This is in line with previous research [4] regarding shoulder injuries in athletes with various physical impairments.
Frequency of injury
Athletes with single and double trans-tibial limb deficiency reported glenohumeral joint, neck and shoulder and elbow joint injuries. This is perhaps not surprising given maximal strength and power needed for optimising overhead performance is dependent on the transmission of kinetic energy, created in the lower limbs, to the shoulder via the pelvis [17]. According to Kibler [18], the shoulder is central to the kinetic chain, through transference of force from the lower limbs to the hand via the trunk. In athletes with lower limb deficiency, this is disrupted and results in significant strength discrepancies between the residual and contralateral limb [10, 11].
Where fewer injuries were reported in athletes with transfemoral limb deficiency this may be a consequence of participation in wheelchair rather than ambulant sports, and there being a protective effect of the equipment for the upper quadrant, contributing to fewer shoulder injuries [19]. Athletes with upper limb deficiency present with spinal asymmetries, lateral shift, scoliosis, and shoulder elevation on the side of limb deficiency [20], potentially contributing to injuries in this region. Disruption to the kinetic chain in athletes with lower limb deficiency could result in an increase in forces being transmitted through the thorax resulting in musculoskeletal injury [21].
Neck and shoulder were most the most frequently reported site in relation to exacerbation. For some, this could be a consequence of wheelchair propulsion [22]. Recovery from neck and shoulder injuries may require rest from sporting activity however, wheelchair dependant athletes will require their upper limbs for activities of daily living e.g. transfers, which may account for the increased numbers of injury exacerbations and reoccurrences.
There are many variations and inconsistencies of injury types within injury surveillance literature [16] making comparison difficult. Early consensus statements advocated that injury types are based on return-to-play criteria allowing for improved reporting consistency and comparisons to be made across sporting populations [23, 24]. The most recent consensus statement from the International Olympic Committee (IOC) details a robust methodological framework to support comprehensive recording and reporting of epidemiological data on injuries [15] which is needed to improve injury surveillance in Paralympic populations.
Clinical findings
From the athlete history, a recent increase in training volume or intensity was reported as a contributing factor. There is no research investigating training workloads and injury onset in a Paralympic population yet it has been reported that an increase in acute training loads can be a predictor of injury in able-bodied athletes [25], particularly subjective workloads [26]. In the absence of more detailed internal and external training load data and a lack of understanding regarding the impact of unique individual biomechanics, definitive conclusions cannot be drawn. Finding from this study infer that athletes with traumatic limb deficiency may be more susceptible to training-related injuries. This may be a consequence of taking up sport at a later age, compared with athletes with congenital limb deficiency, and therefore demonstrate a reduced chronic workload.
Falls were also reported, particularly in athletes with lower limb deficiency, and supported by previous research in a non-athletic limb deficiency population [27]. The authors are not aware of research investigating the cause of falls in an athletic population with limb deficiency. It is feasible that an athletic population participates in higher level activities compared with a non-athletic population thus increasing their risk of falls. The contribution of equipment, such as prosthetics to falls is unknown with only 2% reporting this as a contributing factor to injury onset.
Joint stiffness was the largest clinical finding for injury presentation followed by posture, and scapular dyskinesia. It is documented in the literature that there is an association between altered scapula kinematics and upper quadrant pathology [25, 28] which could have contributed to the high levels of injuries reported within the shoulder complex. Whilst relatively under researched the relationship between the thoracic spine and upper quadrant has recently gained some momentum, with evidence of a kinematic relationship between mobility in the thoracic spine and shoulder [29] and neck [30]. With a recent review synthesising evidence of thoracic spine exercises for mobility, motor control, work capacity and strength, there now exists a clinical reasoning framework to support personalised exercise prescription and rehabilitation for athletes with impairments [31].
Conservative injury management and onward referral
Injury diagnosis in the majority of cases was based on clinical assessment by a physiotherapist, supported in some cases by a doctor, rather than medical investigation. Clinical diagnosis may vary between and within professions [32] and is in part illustrated here with the number of different terms used to suggest an injury if the shoulder region. Diagnoses such ‘non-specific shoulder injury’ may have an unclear diagnosis, and thus account for the increased number of injury recurrences and exacerbations. In the absence of a clear clinical diagnosis along with etiological factors contributing to a clinical complaint, management is likely to be less effective and recovery may take longer [33].
Where just 50% of athletes received exercise rehabilitation, this was likely a consequence of collaborative and multidisciplinary management involving strength and conditioning coaches. Where these data were not recorded by the physiotherapists, caution should be taken in drawing definitive conclusions regarding scope of injury management and in particular the use of exercise within rehabilitation.
In this study, it was unclear on termination of treatment whether the injury had fully resolved and if the athlete had successfully returned to play. This limits the accuracy of the results as the level of sporting activity that the athlete returned to and when, remains unclear [16]. As a result, we defined injury recurrence as occurring more than 6 months after the onset of the index injury, proposing that at this stage of tissue healing, injuries would be in the remodelling phase and therefore athletes are likely to have returned to play.
Strengths and limitations
Data was drawn from all elite athletes with limb deficiency during a 12-year period. Despite the relatively small sample, important findings regarding injury frequency across different groups with limb deficiency provide a foundation for further research. Where the researcher was blinded to each individual sport, researcher bias was minimised. Blinding to individual sports was on the contrary a significant limitation and precluded evaluation of injuries for specific sports. To draw valid conclusions and make recommendations for injury prevention strategies for specific sports this information would be useful. Information regarding wheelchair dependency would also give an insight into possible risk factors for this population and a deeper insight into protective effects from shoulder injury e.g. disruption across the kinetic chain.
Poor reporting and lack of standardisation precluded the assessment of injury severity, previously defined by Fuller in 2006 as, ‘the number of days from date of injury to the date of return to full participation in training, and availability for match selection’ [16]. We are therefore unable to compare current findings with previous research of athletes with disabilities [4]. Additionally and in line with recently published guidelines [15] data to accurately report time for return to play following injury was not possible.
Data were taken from medical notes that lacked sufficient detail, with over 50% of injuries providing no aetiological data or clinical findings for analysis, including 34 data sets with missing information. The main reason for missing data was treatment by a practitioner who did not have access to either of the electronic medical record systems, ‘PDMS’ and ‘I-Zone’. In addition, inconsistencies in terminology used between clinicians, and diagnoses based on clinical assessment at this time may have influenced the number of specific injuries recorded.
Practice and research recommendations
Consistent use of language, terminology and accurate medical records are required for detailed injury surveillance and the development of effective strategies to mitigate the threat of injury in Paralympic sport. The adoption of IOC Consensus Statement [15] would enhance the consistency and quality of data used to underpin preventative approaches directly relevant and accessible to practitioners and athletes with limb deficiency. As Finch states, ‘standardised injury data collection is crucial to underpin the provision of safe opportunities for all those who participate in sport’ [34] and this is no different for athletes with physical impairments.
