Athletes Are Returning To Sport Too Early Following ACL Surgery

Athletes Are Returning To Sport Too Early Following ACL Surgery

ACL , Education

Often athletes define success by getting back on the field first, they want to beat every deadline, and rush back too quickly. The result is that athletes are returning from ACL surgery too soon and it is contributing to higher re-injury risk and decreased performance.

Current guidelines suggest an average ACL rehabilitation period lasts 9-12 months and suggests an assessment of readiness for return to sport using strength and hop tests as well as movement quality measures1.  Thus, simply measuring the time following surgery does not ensure all athletes are actually ready to return to sport. Subjective and objective testing measures must be passed, demonstrating that the athlete is capable of meeting or exceeding their sport demands physically, psychologically, and emotionally. As mentioned in a previous article, rate of force development and strength measures should be taken as distinct measures and thus both variables need to be passed prior to return to sport. Beischer et al. found that 42% of adolescent and adult athletes returned to sport at 8 months and 67% returned after 12 months. Interestingly, adolescents were more likely to have returned at 8 months than their adult counterpart. Going further into the research, when evaluating the limb symmetry index (meaning how equal their strength was from the uninvolved to the involved leg) at 8 months and 12 months, only 29% and 20-28% of patients had achieved > 90% limb symmetry index respectively using isokinetic strength tests, and single leg hop tests2. Meaning, that less than one-third of athletes are actually meeting objective criteria but are still cleared to return to sport.

Considering the findings that muscle strength is often improved prior to rate of force development after ACL, it is possible that rate of force development measures were even further lacking in these subjects, although this is only speculative. To validate this speculation Knezevic et al. and Larsen et al. found that both rate of force development and maximal quadriceps strength were below the standard considered safe to return to sport but asymmetries in rate of force development were greater than asymmetries in maximum strength3,4. These findings further support the notion that passing validated tests should be essential to determine appropriate return to sport instead of time since surgery.

One variable to consider when assessing limb symmetry index for return to sport is that the uninjured leg may experience disuse atrophy and functional deficits which may alter the validity of the current limb symmetry index. Thus, it has been suggested that the use of pre-injury values or comparing to age, sex, and ability matched healthy controls be a more valid comparison5. Individuals that were 6 months post ACLr and cleared to return to sport were found to have 22% deficit in maximal strength and 26-28% deficit in RFD measures when compared to contralateral limb. Additionally, when the operated limb was compared to pre-ACLr values, the asymmetry was even greater, at 39% deficit3.  Meaning, single leg strength was still significantly reduced comapred to pre-injury status.

These results are additionally supported at time points of 9-12 months which found deficits in limb symmetry index and greater deficits in maximal strength, rate of force development, and functional capacity when compared to a healthy control group4. The data suggests that although may be useful to compare measures between limbs, it may be less valid when using the limb symmetry index to determine readiness for return to sport and thus may under prepare the athlete. Unfortunately, we do not have normative data specific to age, gender, body size, sport, position to be able to reliably compare to, but O’Malley et al. sought to provide normative values in a subgroup of young adult males involved in multidirectional field sports. Their findings suggest that this specific population should strive to achieve an isokinetic knee extension peak torque of 260% of their body mass, single leg vertical jump of >17cm, and achieve > 90% limb symmetry index in strength and hop tests before discharging to RTS6. This is a novel guideline and should be applied cautiously to only the population of young adult male multidirectional field sport athletes but is perhaps more rigorous and specific to achieve the ability to safely meet sport demands.

If you want to see where you stack up in your ACL rehab, download our Free ACL Scorecard which lays out objective criteria to meet before you go back to play.

Following along for our next post discussing the Clinical Practice Guideline’s final variable recommended to return to sport: assessment of movement quality.

Are you an athlete who recently suffered an ACL injury, is currently undergoing ACL Rehabilitation or are looking for that next step to bridge the gap from ACL physical therapy to Return-to-Play? We work with all types of athletes recovering from ,ACL injuries, taking them through a detailed process to return them back to sport safe and prepared to play!  We focus on areas such as strength restoration, movement re-education and objective testing with the latest strength and force plate technology to assess progress and readiness for return-to-play. Learn more about our 5 step approach to ACL Rehabilitation, or reach out today to schedule a free consultation to see if we can help you.



  1. Van Melick N., van Cingel R.E.H., Brooijmans F., Neeter C., van Tienen T., Hullegie W., der Sanden M.W.G.N. Evidence-based clinical practice update: Practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus. Br. J. Sports Med. 2016;50:1506–1515. doi: 10.1136/bjsports-2015-095898
  2. Beischer S, Senorski EH, Thomee C, Samuelsson K, Thomee R. Young athletes return too early to knee-strenuous sport, without acceptable knee function after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 2018;26(7):1966–74.
  3. Knezevic OM, Mirkov DM, Kadija M, Nedeljkovic A, Jaric S. Asymmetries in explosive strength following anterior cruciate ligament reconstruction. Knee. 2015;21:1039–1045.
  4. Larsen JB Farup J Lind M Dalgas U. Muscle strength and functional performance is markedly impaired at the recommended time point for sport return after anterior cruciate ligament reconstruction in recreational athletes. Hum Mov Sci. 2015;39:73–87.
  5. 18Mirkov DM, Knezevic OM, Maffiuletti NA, Kadija M, Nedeljkovic A, Jaric S (2017) Contralateral limb deficit after ACL-reconstruction: an analysis of early and late phase of rate of force development. J Sports Sci 35:435–440.
  6. O’Malley E, et al. Countermovement jump and isokinetic dynamometry as measures of rehabilitation status after anterior cruciate ligament reconstruction. J Athletes Train. 2018;53(7):687–95.