Return to sport following an ACLR

Return to sport following an ACLR

Adrian D'Costa



  1. To assess the percentage of patients achieving symmetrical knee function 6 months after primary ACLR.

  2. To identify factors affecting its achievement, in a large cohort.



  1. A total of 4341 patients who underwent primary ACLR from 2000 to 2015 and were assessed at the 6-month follow-up with the isokinetic quadriceps and hamstring muscles strength tests and the single-leg-hop test were identified.

  2. Subjects with concomitant ligament injuries and contralateral ACL injuries were excluded.

If you want to learn more about ACL rehab, you can subscribe and watch the lectures of ACL experts Kieran Richardson, Bart Dingenen, Lee Herrington here: Click here

OUTCOME MEASURES (Limb Symmetry Index - LSI):

  1. Isokinetic quadriceps strength.

  2. Isokinetic hamstrings strength.

  3. Single leg hop test.

*Patients who reached a LSI of ≥ 90% in all three tests were considered to have achieved symmetrical knee function.*



  1. A total of 1463 patients (35.7%) in the studied cohort achieved symmetrical isokinetic quadriceps muscle strength. The odds of achieving symmetry reduced with age (>30), females and associated meniscal injury. Hamstrings (HT) autografts increased the odds of achieving symmetry compared to bone-patellar (BPTB) autografts (36.6% vs. 16.1%).

  2. The total number of patients who achieved symmetrical isokinetic hamstring muscles strength was 1,935 (47.3%). The odds of achieving symmetry reduced with age (>30), delayed ACLR (>3/12), HT autograft and cartilage injury.

  3. The patients who achieved a symmetrical performance in the operated limb in relation to the healthy limb for the single-leg-hop test were 2,405 (67.9%) - *data for the single-leg-hop test were available for 3541 patients*. The odds of achieving symmetry reduced with age (>30), females, delayed ACLR (>3/12), meniscus injury/repair and cartilage injury. A high Tegner score of >6/10 increased the odds of symmetry along the use of a HT autograft.

  4. A total of 693 patients (19.6%) achieved symmetrical knee function, reaching a LSI of ≥90% in all three tests.


This might seem like a repetitive message - “athletes being under-cooked during an ACL rehab.” Sure you’re right, but advocating the message with multiple pieces of evidences, starts to form a clearer and strong message that WE NEED TO BE BETTER.

What this article demonstrates really well is compensation. Subjects performed quite well (comparatively) in a single leg hop test with 67.9% attaining >90% LSI. In isolation, this would suggest that the subjects attained a reasonable level of strength. When you look at single leg hop data against the isokinetic data for both Hamstrings and Quads there is far different picture being painted. The cumulative data demonstrates a very likely compensation in landing strategy (hip) that would require far less quad control. This would look like a subject landing with a more extended knee, which has its own implications.

This study also demonstrates the deficits in strength and hop distance in older subjects and females. Subsequently, when treating individuals that fall into this group, it's important to implement age and gender specific parameters in your rehabilitation program. Similarly, those suffering additional meniscal injury may need to have a longer and slower progressing rehab.

Choice of chosen graft will also influence rehab. Those who have HT autografts are more likely to experience deficits in knee flexion strength vs. knee extension strength deficits in those having BPTB autografts. Subsequently this should be reflected in your rehab programs.

This study does state that they did not take baseline measures on the contralateral limb, so we need to factor in what we now know about deconditioning to the contralateral limb. Perhaps the data presents better that it should? Regardless, the data is NOT a good display of how much importance we need to place on testing appropriately and passing LSI markers prior to return to sport.

What are your thoughts?

Only one patient out of five achieves symmetrical knee function 6 months after primary anterior cruciate ligament reconstruction - Cristiani et al. (2019)



If you want to learn more about ACL rehab, you can subscribe and watch the lectures of ACL experts Kieran Richardson, Bart Dingenen, Lee Herrington here: Click here

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