Fear of reinjury after ACL surgery: how common, what helps

The short answer: being afraid of doing it again is the most common reason people give for not going back to their sport after ACL reconstruction, ahead of a knee that does not work. In a pooled review of 28 studies, two thirds of those who did not return gave a psychological reason, and three quarters of those named fear of reinjury. The fear is measurable, it usually eases over the first year, and the thing it tracks most closely is how the knee itself feels and performs. Whether your own knee is ready for sport is a decision for your surgeon and physiotherapist; what follows is what the research says about the fear, not about you.

How common it is

Kvist and colleagues questioned patients three to four years after reconstruction: 53 per cent had returned to their pre-injury level of activity, and those who had not scored higher on the Tampa Scale of Kinesiophobia, a questionnaire about fear of movement. Larger studies have found the same since. Ardern and colleagues surveyed 164 people in Sweden one to seven years after surgery: 40 per cent had returned to their pre-injury activity, and the reasons the rest gave were not trusting the knee (28 per cent), fear of a new injury (24 per cent) and poor knee function (22 per cent). Psychological readiness was the factor most strongly associated with being back; age, sex and pre-injury level were not related at all.

Nwachukwu and colleagues pooled 28 studies with 2,918 patients in 2019: of the 795 who had not returned to play, 64.7 per cent cited a psychological reason, and 76.7 per cent of those named fear of reinjury. The 2023 Aspetar clinical practice guideline states it without hedging: psychological factors, particularly fear of reinjury, are the most significant contributors to not returning to sport.

What the ACL-RSI scale measures

The questionnaire you are most likely to meet is the ACL-RSI, the ACL Return to Sport after Injury scale, which Webster, Feller and Lambros published in 2008. Its twelve questions cover emotions about playing, confidence in your performance and how you weigh the risk, combined into a score out of 100, higher meaning readier; in the original 220 patients, those who had given up sport scored clearly lower than those who had returned or meant to. In McPherson and colleagues’ young patients who went on to a second injury, the items that set them apart were being more nervous about playing, less confident in playing without thinking about the knee, more frustrated at having to consider it, and more afraid of reinjuring it.

What the scale is good at is prediction. Ardern and colleagues followed 187 athletes: psychological readiness, fear of reinjury, a sense of control over recovery and the athlete’s own estimate of how long it would take, measured at four months, predicted who would be back at their pre-injury level twelve months after surgery with 86 per cent accuracy. Faleide and colleagues tested 129 patients at nine months with hop tests, strength tests and the ACL-RSI, then checked two years after surgery: 42 per cent had returned to their pre-injury level, the ACL-RSI score and age predicted who, and the hop and strength tests did not.

The scores rise, and they come with no pass mark

Sadeqi and colleagues tracked the ACL-RSI in 681 patients of the French FAST cohort. The average score was 41 before the operation, 55 at four months, 58 at six, 65 at one year and 65 at two years, by which time 58.4 per cent were back in their original sport; a score of 65 or more was the threshold that best separated them. On average, people feel considerably readier at a year than at four months, and the gain then flattens.

Other cohorts draw the line elsewhere: under 47 at nine months flagged the risk of not returning in Faleide’s, and a score under 77 marked the risk of a second injury in McPherson’s younger patients. There is no single pass mark, and a physiotherapist reads the number against the rest of what they can see.

Does fear predict a second injury?

Two cohorts, reported in three papers, say it is associated with one, with the usual cautions. Paterno and colleagues followed 40 patients cleared for sport: those scoring 19 or more on the Tampa scale had a relative risk of 13 for a second tear within two years, with a confidence interval from 2 to 81, a pilot study’s way of saying the direction is clear and the size is not. McPherson and colleagues followed 329 patients back in sport, of whom 52 (16 per cent) suffered a second ACL injury. Across the whole group the injured had scored a little lower at twelve months, 61 against 67 points, not a significant difference, but among patients of 20 and under the gap was 61 against 72 and was. In a second paper on 115 patients of 20 and under, the 21 who were reinjured had barely moved from their pre-operative score while the uninjured had gained about 25 points.

Fear in these studies is a marker, not a demonstrated cause: Paterno’s fearful patients were also six to seven times more likely to fall short on quadriceps strength and hop symmetry, and a person who is frightened of a knee that is objectively behind is not wrong. And none of the 29 patients in Faleide’s cohort who passed its strength, hop and knee-function criteria sustained a second knee injury in two years, although six reinjuries in the whole cohort is too few to build much on.

What helps, on the evidence

A knee that works. Webster and colleagues looked for what explained readiness in 635 athletes cleared for sport at about twelve months: self-reported symptoms and function, together with age, accounted for 37 per cent of the variance, and hop symmetry was associated with higher scores too. The association runs both ways, but the practical reading is that confidence follows evidence from the knee more than it follows reassurance. The measurements clinics use to produce that evidence are covered in hop tests after ACL surgery.

Exposure, in stages. The Aspetar guideline suggests one reason fear persists is that patients are not exposed enough to sport-specific training before they play, and it separates clearance to train from return to competition. The 2016 Bern consensus statement on return to sport, from Ardern and seventeen expert clinicians, describes the return as a continuum alongside rehabilitation rather than a verdict at the end of it, decided jointly by clinician, athlete and coach, and Noyes’ Knee Disorders describes the same structure of phases ending in running, jumping and cutting before sport. Fear has more to feed on when the first full-speed cut happens in a match.

Psychological interventions, so far thinly tested. Coronado and colleagues found four randomised trials of psychosocial treatments after reconstruction, 210 people in all, testing guided imagery and relaxation, coping modelling and visual imagery. The findings were inconsistent for function, pain and self-efficacy, limited for quality of life, anxiety and fear of reinjury, and no trial measured return to sport. That is an absence of good evidence rather than evidence against; a clinic with a sports psychologist may well involve one.

Saying it. The Aspetar guideline lists psychological readiness, measured by the ACL-RSI or the Tampa scale, among its criteria for clearance. Fear is otherwise invisible to a clinic that is measuring strength, and a score that has not moved while the knee’s numbers have is worth putting into words at an appointment.

Where the app fits

Fear of reinjury belongs to Levels 6 to 10 of the programme in ACL Recovery Tracker, our free ACL rehab app for iOS and Android: the levels that build single-leg strength, landing, running and finally cutting, the last of which asks for a clinician’s clearance and at least nine months since surgery. The app has no ACL-RSI and does not measure fear, and how to choose an ACL rehab app says what one can reasonably be expected to do. What it holds is the record of the knee doing more each week, the sessions logged and the criteria you tick off yourself, a record of what the knee can do, which is what Webster’s study found readiness tracks most closely, and the pain diary, which records whether the knee itself complained afterwards.

Fear of reinjury is not a weakness and not a verdict. It is the most frequent reason this operation ends with someone watching from the touchline, it responds to time and to a knee that proves itself, and the people clearing you for sport have a questionnaire for it. The person who has to fill it in honestly is you.