Predicting Full Return-To-Sports After ACL Surgery

Athletes are often surprised when the surgery they had for a torn anterior cruciate ligament (ACL) doesn't get them back in the game at their preinjury level of participation. That's why they had the surgery. And that's what they expected as a final outcome. Physical therapists are asking the question, Could it be because rehab ends too soon?

What is the optimal length of time for rehab after ACL reconstruction? What impairments (physical problems, loss of function) are present to keep the athlete from returning to sports full speed ahead?

In this study, sports physical therapists look at how knee impairments such as loss of motion, decreased strength, and swelling interfere with function after surgery. They also investigate the effect of kinesophobia (fear of movement and/or reinjury) on return-to-sports activities.

Other studies have attempted to look at the association between knee impairments and sports performance. But the authors say that a closer look at those studies reveals too many demographic differences among patients to really make a comparison. Demographics refer to patients' age, gender, weight and height or body mass index (BMI), general health, time from surgery, and so on.

The patients included in this study had an ACL reconstruction procedure six to 12 months ago. They were all involved in some type of moderate-to-high level recreational or competitive sports before the injury occurred (and before the surgery was done). After surgery, everyone went through a rehab program but not necessarily the same one. The study did not require a uniform rehab protocol.

Impairments such as knee effusion (swelling), joint range of motion, joint laxity (looseness), and muscle strength were measured by highly specialized sports physical therapists. The specific clinical tests and measures for each of these variables was described in detail. All tests were conducted on the surgical as well as the nonsurgical side (for comparison).

The patients also filled out a survey asking them questions about their pain intensity and general quality of life (physical and mental health). They also completed the Tampa Scale of Kinesophobia (TSK-II) to test for fear of movement or reinjury. The higher the score on the TSK, the greater the likelihood of pain-related fear of movement/reinjury.

Patients who interpreted pain to mean they had injured themselves or who were afraid they might injure themselves if they exercised had higher scores on the TSK-II indicating various levels of kinesiophobia. The patients also completed a self-report on knee (physical) function.

A well-known test called the International Knee Documentation Committee (IKDC) subjective form was given. This 10-question test relates knee symptoms with physical function. It is very reliable for assessing function after ACL injury and/or repair or reconstruction.

The surveys and questions were all considered self-report measures. A second category of clinical tests referred to as performance-based measures were also administered. The performance-based test used in this study was a single-legged forward hop test. Standing on one leg, the patient hopped forward as far as possible (always landing on the same leg). Both sides were tested (nonsurgical side first) and compared.

The data was collected and analyzed taking into account all the demographic variables. The results showed that what patients thought they could do and what they could really do were two different things. By self-report, their physical function was much lower than what they could actually do during the physical tests (motion, strength, hop-test). Thus, it appears that self-report versus performance-based assessment can give different results.

In the self-report area, patients perceived that pain intensity and fear of movement limited function. Fear-avoidance behaviors of this type are commonly reported in studies on back pain. Fear-avoidance is considered a psychologic variable.

The concept has been less well studied in knee injuries such as after ACL surgery. The authors suggest that these two areas (pain intensity and fear-avoidance behaviors) would be good targets for rehabilitation. This is especially true for athletes who are not satisfied with function after surgery and want to get back to a preinjury level of activity.

Performance-based testing with the single-legged hop test showed that joint swelling was the main factor preventing a passing score. Strangely enough, the more effusion the patient had, the more likely they were to be able to complete the single-legged hop test. The authors could offer no logical reason for this finding.

Not everyone met the necessary criteria to even take this test. Only 39 of the 58 patients had enough motion and strength to perform the test safely. Patients were more likely to be able to take (and pass) the test 12 months after surgery compared to six months postop.

The authors conclude that this study has identified pain intensity as the main knee impairment and kinesiophobia as a psychologic barrier for some athletes who want to return to full sports participation but don't. The next step would be to see if it's possible to predict (ahead of time) which patients will develop participation restrictions.

If a decline in self-report function can be tested early on, it may be possible to develop a rehab program and guidelines for these athletes. It would be aimed at maximizing the number of athletes who get back to full sports participation. They would also look for other (better) ways to assess performance than the hop test. Having both a self-report and performance-based assessment might yield more accurate predictions.


Trevor A. Lentz, PT, CSCS, et al. Factors Associated with Function After Anterior Cruciate Ligament Reconstruction. In Sports Health. January/February 2009. Vol. 1. No. 1. Pp. 47-53.


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