The right ankle. Always the same one. The first time was in September, at training, a twisted landing on a slippery pitch: ice, three days' rest, a bandage, and back to it. The second time in February, in a match. The third in May, and this time he did not even call from the pitch because it was "the usual one". You, meanwhile, are doing the sums and realising that there have been three of the "usual" in one season, and that each time the swelling seems to take a little longer to go down.
You are not the only one doing this sum: in American high schools, out of 5,373 ankle sprains recorded over six sporting seasons, 15.7% were recurrences, an ankle that had already been hurt. That is the share of sprains that were repeats, not the individual risk of getting hurt again, but it shows that the phenomenon you have at home is as common as it seems.
It is not bad luck, and it is not that your child "is just made that way". And once the situations below are ruled out, it is usually not a problem that gets solved by ordering one more test.
It is one of the best-documented phenomena in sports medicine: among the most solid predictors of a new injury is having already had one. And when the first episode involved a specific body part, the risk of a new injury in that same part is also higher, with the caution you will see shortly, because it is better documented in some groups than in others. The point is that this is not a sentence: it is a description of what happens when recovery stops too early. And a recovery that stops too early can be recognised and corrected.
Red flags: when it is not a sports recurrence
There are pains that look like an injury coming back but are not. Some should not be managed at home or left until the next match.
A&E today, not tomorrow:
- after the trauma, cannot put weight on it or take a few steps, the limb looks bent or deformed, the joint locks or gives way, or it has swollen within a few hours, especially if a pop was heard at the moment of impact;
- fever together with a swollen, hot and painful joint without any trauma: an infection of the joint must be ruled out today, not waited on;
- a blow to the head followed by loss of consciousness, repeated vomiting, drowsiness, confusion that gets worse, or a severe and increasing headache.
Out of play immediately, and seen in the following days:
- a blow to the head with confusion, nausea, headache or even just a feeling of being slowed down: they come off straight away and do not return that day, even if they say they feel fine;
- pain that is there at night, at rest, and wakes them, instead of appearing with movement and easing with rest, especially if it comes with general malaise or weight loss;
- a point that is tender to pressure in exactly the same millimetre of bone, that gets progressively worse for more than two or three weeks: this is the typical pattern of overuse bone stress, to be seen before it becomes a fracture, and in the meantime the movement that causes pain is stopped;
- the same spot has hurt for more than four to six weeks despite rest, or they have been limping for more than a week.
Outside these cases, what follows concerns exactly the situation you have at home.
The first injury is one of the strongest predictors of the second
The clearest data on young people come from a prospective study of young American footballers from the under-12 to under-18 categories. 1,483 boys and girls were followed, for a total of 5,139 player-seasons and about 171,957 exposures between training sessions and matches: numbers that make the result hard to explain by chance.
The overall rate was 4.6 new injuries per 1,000 exposures. But when broken down by clinical history, the picture changes: those who reported one previous injury had a rate of new injuries 2.6 times higher (95% CI: 2.0-3.3) than those who had never had any; those who reported two or more reached 3.0 times (95% CI: 2.3-3.8). More than half of the young people, 59.7%, reported at least one injury in their past.
It must be said honestly what this study measures and what it does not: the injury history was self-reported, and only 19% of the young people contacted responded to the initial questionnaire, which makes it possible that those who had been hurt were more motivated to take part. And above all: here the count concerns new injuries in general, not necessarily in the same spot.
For the same spot another study is needed. A cohort of young basketball and floorball players up to age 21 (211 boys with a mean age of 16.1 years, 183 girls with a mean age of 15.5 years) was followed for up to three years to record acute knee injuries. In girls, a previous acute knee injury multiplied by 2.6 the risk of a new acute injury in the same region (95% CI: 1.3-5.2), adjusted for age and body mass index. In boys the association appeared in the crude analyses, but the authors could not adjust it: there were only 18 knee injuries among the boys, too few. It is a limitation that must be reported, not hidden.
In the most studied case of all, the anterior cruciate ligament, the scale of the phenomenon becomes striking, provided one is clear about who is being referred to. A systematic review selected 19 studies on people who had undergone cruciate reconstruction and combined the data by subgroup, each with its own set of studies: the rate of a second cruciate injury (same knee or contralateral) was 15% overall (7 studies, 23,740 patients), rising to 21% under 25 years old (6 studies, 2,140 patients) and to 23% in those who are young and return to sport (4 studies, 913 patients): nearly one in four. These are teenagers and young adults who had cruciate surgery and returned to high-risk sport, not children training twice a week: the figure describes that situation. We cover this in more detail in when a teenager can return to play after an injury.
What is left behind: strength, control, confidence
If the first episode predicts the second, the question becomes: what exactly is left behind? Three things. And the feature they share, the one that makes the whole mechanism so insidious, is that none of the three hurts.
Strength. The muscle that protects the joint weakens during the days of rest, and its recovery does not keep pace with the disappearance of pain. In the Delaware-Oslo cohort, of 106 athletes from disciplines involving changes of direction, aged 13 to 60, mean age 24, followed for two years after a cruciate reconstruction, greater quadriceps strength symmetry before return significantly reduced the rate of knee re-injury: about 3% fewer re-injuries for every percentage point of symmetry gained (p = 0.03). It did not "make them feel better": it reduced the re-injuries that were measured. It is worth stating this clearly, because it is the easiest mistake to make: that cohort consists of older teenagers and adults who had knee surgery, not of children with an ankle. The principle, measuring instead of inferring from the absence of pain, can be transferred; the figure cannot.
And that the moment of return often comes before recovery is shown well by a study of 115 young athletes already cleared to resume sport after a cruciate reconstruction: only 13.9% met all the recommended criteria together (strength and jump symmetry above 90%, plus the questionnaire on knee function); on the individual tests the share passing each one ranged from 43.5% to 78.3%. Cleared does not mean recovered.
Control. This is how they land from a jump, how they brake, how they change direction. After an injury, compensation strategies often remain that no symptom signals any more. It is the most widely accepted explanation for why the movement becomes risky again, but it must be said that in young people the evidence on this point is still limited: what is measured well is the symmetry of strength, the only one of the two that, in the data, withstood statistical testing.
Confidence. It seems the vaguest of the three and yet it is the only one that someone has tried to measure directly in relation to re-injuries. Among 329 patients who returned to sport after a cruciate reconstruction, 52 (16%) had a second injury. Looking at the whole group, the difference in psychological readiness at 12 months between those who got hurt again and those who did not did not reach statistical significance (60.9 versus 67.2 points; p = 0.11), and this must be said, because the figure is often presented as if it were clear-cut. But breaking it down by age something emerges: in young people aged 20 or under the difference was there and significant (60.8 versus 71.5 points; p = 0.02), while in older patients it disappeared (60.9 versus 64.6; p = 0.58). In the younger group, then, the signal is there, and in adults it is not. However, this is a comparison between subgroups, arising from an analysis by age band within a single study: a solid clue, not a closed proof.
Why "when it no longer hurts" is exactly the mechanism that generates the re-injury
Now the pieces fit together. Pain is usually the first symptom to go. Strength, control and confidence run on a slower clock. If the criterion for returning to the pitch is the absence of pain, the return very often falls in the window in which the joint is still exposed: this is exactly what is seen in the young people already cleared to resume, where fewer than one in seven met all the criteria.
The teenager is not exaggerating or lying. They are reporting with precision the only information they have access to. A strength deficit compared with the other leg is not felt; a landing that has stopped being symmetrical is not felt. They are measured, and if nobody measures them, nobody sees them, until something breaks again.
Still in the Delaware-Oslo cohort, among those who completed the battery of return criteria, those who did not pass it were re-injured in 38.2% of cases (21 of 55), against 5.6% of those who passed it (1 of 18). But it must be reported in full: that comparison rests on 73 people and a single injury in the passed group, and it did not reach statistical significance (risk ratio 0.16; 95% CI: 0.02-1.20; p = 0.075). The direction is marked and consistent with the rest of the literature, but the single study is not enough to prove it on its own. What did reach significance is the finding on time: the rate of re-injury fell by 51% for every month in which the return was delayed up to 9 months after surgery, with no further gains beyond that threshold.
Training load that rises too quickly: what is known and what is not
Then there is the chapter on training that suddenly increases: the tournament, the move up a category, the summer camp, two sports in the same period. Here honesty requires scaling down a story that circulates widely.
On one hand, in a study of young tennis players followed for seven months, both the ratio between the load of the last week and the four-week rolling average (p < 0.001) and the history of previous injuries (p = 0.003) predicted injury in the following week. In the week before an injury that ratio was on average 1.57: roughly one and a half times the usual load. But the players included in the final analysis were 26, a small number on which to build a rule.
On the other hand, a cohort of 244 middle-school children monitored week by week found no association between that ratio and injuries. On the contrary: a higher and steadier training volume in the 2, 3 and 4 weeks before was associated with fewer acute injuries in the following week.
The cautious reading, the one that holds across both studies, is this: the problem is not that your child trains a lot, it is that they go abruptly from little to a lot. The consistently trained child is not the most exposed; if anything, the opposite. If you want to look more closely at how overload is recognised before it becomes an injury, we have written about it in the teenager who trains too much: the signs.
What to do: return criteria, not just dates
The change of mindset is all here: you return when tests are passed, not only because time has gone by, with one caveat that comes from the same data. In the Delaware-Oslo cohort the statistically solid result was precisely the one about the calendar (fewer re-injuries for every month gained up to 9 months after surgery), while the comparison between those who passed and those who did not pass the criteria did not reach significance. Criteria and time are not alternatives: after a cruciate operation both are needed. In practice this means four things.
Measure instead of asking. Before returning, the strength of the injured limb is compared with the healthy one, single-leg hops are checked, a landing is observed. In the Delaware-Oslo cohort the threshold for considering the criteria passed was a score above 90% on all the tests.
Rebuild strength for real. Not the exercises of the first few days repeated for weeks, but a load that increases over time until the gap with the healthy side closes.
Retrain the movement that caused the injury. If they got hurt landing, you retrain the landing; if changing direction, you retrain the change of direction, progressively, before they do it in a match at full speed.
Do not treat fear as a detail. In younger people it is associated with re-injuries, and it is worked on by exposing them gradually and in a controlled way to what they fear, not by asking them to be brave. No study has yet shown that working on fear reduces re-injuries: what we know is that those who carry it with them have suffered more of them.
On prevention, fortunately, the evidence is better. A systematic review of youth sport included 25 studies and limited the meta-analysis to randomised studies only: neuromuscular training programmes (strength, balance, control of jumping and landing, done consistently as part of the warm-up) reduce the risk of lower-limb injury by 36% (incidence rate ratio 0.64; 95% CI: 0.49-0.84). For the knee alone the estimate pointed in the same direction but did not reach significance (0.74; 95% CI: 0.51-1.07): the protection shown concerns the lower limbs as a whole. The authors stress that the real obstacle is not effectiveness: it is that these programmes are adopted rarely and kept up even less.
The step that is usually missing
If you reread the story of the right ankle in the light of all this, what stands out is not what was done after the first episode. It is what was not done afterwards: nobody measured when that ankle was as strong as the other again, because the pain had gone and that seemed enough. The second and third episodes, very often, are not new injuries: they are the same injury that never finished healing.
With Ri-Hub Junior you start with a free 20-minute first consultation by video call with a physiotherapist on the Italian professional register who works with children and teenagers: you tell us the story of the episodes, we look together at how they move and how they load, and we tell you what has been left behind and what is needed to close the circle. Up to age 10 sessions last 50 minutes and cost 59,90 €; from age 11 to 18 the standard session at 29,90 € applies.
Sources
- Injury history as a risk factor for incident injury in youth soccer: British Journal of Sports Medicine, 2005
- Injury History and Perceived Knee Function as Risk Factors for Knee Injury in Youth Team-Sports Athletes: Sports Health, 2023
- Risk of Secondary Injury in Younger Athletes After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis: The American Journal of Sports Medicine, 2016
- Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study: British Journal of Sports Medicine, 2016
- Psychological Readiness to Return to Sport Is Associated With Second Anterior Cruciate Ligament Injuries: The American Journal of Sports Medicine, 2019
- The Acute:Chronic Workload Ratio Is Associated with Injury in Junior Tennis Players: Medicine and Science in Sports and Exercise, 2020
- Training Load and Injury Among Middle School-Aged Athletes: Journal of Athletic Training, 2020
- Neuromuscular training injury prevention strategies in youth sport: a systematic review and meta-analysis: British Journal of Sports Medicine, 2015
- Young Athletes Cleared for Sports Participation After Anterior Cruciate Ligament Reconstruction: How Many Actually Meet Recommended Return-to-Sport Criterion Cutoffs?: Journal of Orthopaedic & Sports Physical Therapy, 2017
- Epidemiology of U.S. high school sports-related ligamentous ankle injuries, 2005/06-2010/11: Clinical Journal of Sport Medicine, 2013
Last source check: September 2026.
