Patient characteristics and predictors of return to sport at 12 months after anterior cruciate ligament reconstruction: The importance of patient age and postoperative rehabilitation

BACKGROUND & OBJECTIVE

Returning back to pre-injury levels of sport following anterior cruciate ligament reconstruction (ACLR) is a common goal that patients strive for, however the amount of non-professional patients that achieve this goal by 12 months is around 60% [1] compared to 83% of professional athletes [2]. Although ACLR patients may return back to some level of sport at around 12 months post-op, studies show that they may be returning back to sport prematurely with inadequate levels of strength and function, which ultimately may put their ACL graft, or their opposite ACL, at risk of injury [3, 4].

The objectives of this paper were three-fold:

1. Compare the physical profile of patients who had, and who had not, returned to sport at 12 months.
2. Attempt to identify predictors of return to sport at 12 months.
3. For those who had returned to sport, attempt to evaluate differences in strength, hop function and self-reported function based on the patient’s age and rehab quality.

Ensure that you and your ACL reconstruction patients meet the current best practice guidelines for rehabilitation: A structured and supervised rehab plan for at least 6 months post-op, and returning to sport after 9 months after passing a series of strength, function and patient-reported outcome measures.

METHODS

113 ACLR patients (75 male and 38 female) who were involved in either level I or II sports prior to ACL injury were evaluated between 10-14 months post-op following ACLR (hamstring autograft). One of the main objectives of the evaluation was to see if they had “passed” a strength/hop test battery. A “pass” was considered if they achieved >90% limb symmetry index (LSI) on all strength and hop tests. A “fail” was considered if they did not meet >90% LSI on one or more of these tests.

The evaluation consisted of:

• Strength tests: Isokinetic strength testing for both quadriceps and hamstrings assessed at an angular velocity of 90 degrees/second
• Hop tests: Single-leg hop for distance, triple hop for distance, triple crossover hop for distance and 6m timed hop test
• Self-reported function: International Knee Documentation Committee (IKDC)
• Rehabilitation quality: Overall ACLR rehab quality was assessed via the grading scale below (directly from the paper - Edwards et al 2018). Note: based on current best practice ACLR guidelines, rehabilitation was classified as “complete” if grades 5-6 were met; and rehabilitation was classified as “incomplete” if grades 0-4 were met.

RESULTS

Of the 113 patients, 64% had returned to their pre-injury level of sport at the time of evaluation (mean 12 months). This is consistent with previous work [1].

In regard to age, those who had returned to sport were not only significantly younger than those who had not (mean age 22yrs vs 31yrs); but across the board, a significantly higher number of ACLR patients who had returned to sport were aged under 25yrs.

In regard to “complete” or “incomplete” rehab, 51% of patients had returned to sport after “incomplete” rehabilitation. Of interest, those who were considered to have “completed” their rehab were significantly more likely to have returned to sport and passed all of the strength and hop test battery.

Furthermore, and although under 25yr patients were significantly more likely to return to sport, 52% of them returned to sport despite not “completing” rehab. In these participants who were aged under 25yrs and performed “incomplete” rehab, only 4% passed the strength and hop test battery compared to 40% who were aged under 25yrs and “completed” rehabilitation.

Overall, a statistical analysis (logistic regression analysis) revealed that “complete” rehabilitation (nearly 8x more likely), aged under 25yrs (nearly 4x more likely) and higher IKDC scores (>88) were predictive of a return to pre-injury level of sport at 12 months post-op.

LIMITATIONS

The authors acknowledged that the study was largely focused on strength and hop test performance symmetry, with other important psychological variables (confidence, fear of re-injury, etc) not assessed. Furthermore, using LSI as an objective measure can over-estimate an ACLR patient’s function as it does not account for contralateral deficits in strength, power and neuromuscular control, and certainly does not account for ipsilateral movement quality during hopping tasks.

CLINICAL IMPLICATIONS

The findings in this study on a cohort of non-professional, community-based ACLR patients are concerning. The fact that there are very low numbers of young ACLR patients “completing” rehab, and “passing” return to sport criteria, is the biggest concern.

Previous work showed that ACLR patients are 4x more likely to sustain a 2nd ACL injury if they do not pass discharge criteria [4]. With previous research also showing that 35% of ACLR patients aged under 20yrs sustaining a 2nd ACL injury (contralateral ACL and ipsilateral graft) within 2-3 years upon return to sport [5], the results of this current study do not bode well for the future knee health of those involved in this study.

Personally, I would be making every effort possible to ensure that you and your ACL reconstruction patients meet the current best practice guidelines for rehabilitation: A structured and supervised rehab plan for at least 6 months post-op, and returning to sport after 9 months after passing a series of strength, function and patient-reported outcome measures.

+STUDY REFERENCE

Edwards P, Ebert J, Joss B, et al (2018) Patient Characteristics and Predictors of Return to Sport at 12 Months After Anterior Cruciate Ligament Reconstruction: The Importance of Patient Age and Postoperative Rehabilitation. Orthopaedic journal of sports medicine, 6(9).

SUPPORTING REFERENCE

1. Ardern CL, Webster KE, Taylor NF, Feller JA. Return to sport following anterior cruciate ligament reconstruction surgery: a systematic review and meta-analysis of the state of play. British journal of sports medicine 2011; 45(7): 596-606.
2. Lai CCH, Ardern CL, Feller JA, Webster KE. Eighty-three per cent of elite athletes return to preinjury sport after anterior cruciate ligament reconstruction: a systematic review with meta-analysis of return to sport rates, graft rupture rates and performance outcomes. British journal of sports medicine 2018; 52(2): 128-38.
3. Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. British journal of sports medicine 2016; 50(13): 804-8.
4. Kyritsis P, Bahr R, Landreau P, Miladi R, Witvrouw E. Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. British journal of sports medicine 2016; 50(15): 946-51.
5. Webster KE, Feller JA. Exploring the High Reinjury Rate in Younger Patients Undergoing Anterior Cruciate Ligament Reconstruction. The American journal of sports medicine 2016; 44(11): 2827-32.