The present study retrospectively analyzed patients with acute LAS treated between 2015 and 2018 in the BG Klinikum Duisburg, Germany. Using PROMS (CAIT & FADI) we collected relevant epidemiological information on the distribution of the CAI rate. We identified a higher risk for CAI in females and persons in the age group of 41 to 55 years and we could show that a later therapy onset after acute LAS is associated with increased functional impairments of the ankle. Therefore, early functional treatment following acute LAS seems to be favorable.
The overall CAI rate was about 17% and thus slightly lower than the CAI rates reported in literature ranging between 20 and 40% (6–8). This could be related to methodological differences in study design such as inclusion criteria and inconsistent terminology according to the definition of CAI. In this study CAI was classified according to the CAIT score, which is a recommended criteria from the International Ankle Consortium (14). Our classification is also supported by the FADI since there was a significant difference in the FADI score between the CAI (78.99%) and COPER groups (97.05%).
According to the sex of our patients we found a higher CAI rate in females (21.2%) than in males (10.3%). The females also had higher CAI rates in each of the three age groups. Literature shows that there is a general higher incidence of ankle sprains in females compared with males (13.6 vs 6.94 per 1,000 exposures) (4). This is supported by a higher CAI rate for females in sport (female athletes 32% vs male athletes 17%) (18). Yet there is no explanation for this prevalence, but there are several assumptions such as increased ankle laxity or decreased postural control in females which may contribute to these injuries (19). Additionally, we speculate that the reduced financial and sportsmedical support in female professional sport compared to their male counterparts might also be a contributing factor. Derived from this, females should focus more on specific prevention programs to reduce the occurrence of LAS.
Doherty et al. (2014) state that the incidence of LAS appeared to decrease with age (4). Our data supports this trend but additionally shows that there is a higher CAI rate in older age groups. Currently there is no literature investigating the age distribution of CAI. On the one hand, the higher CAI rate in older age groups could be related to greater levels of sarcopenia with decreased muscle mass and connective tissue as well as increased impairments in postural or sensorimotor control leading to increased ankle instability (20). On the other hand, we suppose that there is a higher CAI rate with increasing age because older individuals might have a longer history of multiple ankle sprains in their life, which is a major risk factor for developing a CAI (5). This is supported by our data in which patients experiencing 1–3 and 3–5 recurrent sprains have significantly worse CAIT outcomes than patients having no recurrent sprains. Furthermore, the mean CAIT of the groups with 1–3 and 3–5 recurrent sprains is below the cut-off score of the CAIT (CAIT < 24), respectively. This implicates that LAS as an injury should be taken seriously and that the focus should be on regaining function as early as possible to prevent recurrent LAS.
Most subjects experienced their LAS during sport (54.5%). This is in line with literature since ankle sprains have a high incidence among physically active persons (5). Herzog et al. (2019) state that the highest rates in LAS were typically reported in sports that are characterized by running, cutting and jumping (5). In contrast, 33.8% reported everyday life as the cause of injury. The prevalence of LAS is therefore not only limited to a sporting population, instead it is present in a huge variety of patients. Thus, the rehabilitation of LAS should be individualized and adapted to the need of the patient.
Our data show that most treatments started more than four weeks after the initial LAS. Interestingly, there was a significant difference in the CAIT score between patients receiving their therapy immediately and patients receiving therapy after more than four weeks. The latter had a worse outcome because of the later therapy onset (Fig. 4). This is supported by studies showing better outcomes for groups with functional support and exercise therapy in contrast to immobilization (21). Additionally, there was a higher percentage of COPER receiving immediate therapy after acute LAS and accordingly a higher percentage of CAI receiving therapy after more than four weeks or no therapy at all following acute LAS (Fig. 4). We suggest that the timepoint of therapy onset can be seen as a relevant risk factor for the development of CAI. It seems the later the therapy onset after LAS the worse the functional outcome.