Non-operative Treatment of ACL Injury

Description[edit | edit source]

The main objective of ACL reconstruction is to restore the anterior-posterior and rotational joint stability for successful a return to sports, prevention of instability and long-term joint degeneration. The majority of ACL-deficiencies undergo surgical treatment[1].

Despite the wide use of reconstruction, the rate of recurrence is still high, particularly in the first 24 months following the operation[2]. The restoration of joint mechanics may not be sufficient for returning to competency in sports. A systematic review investigated the rate of return to sports after reconstruction and reported 82% of participants return to sports, 63% returning to pre-injury level with only 44% had returned to competitive sport[3] despite successful outcome on knee impairment-based function scales.

In addition, osteoarthritis was still evident 14 years after ACL reconstruction[4] and the evidence supporting ACL reconstruction over conservative treatment is considered weak [5]. A 2018 study by Krause and colleagues found that in terms of functional outcome, it is not possible to conclude whether surgery or conservative management of ACL rupture produces better results.[6] Another study from 2018 found that early ACL repair is not necessarily a prerequisite for individuals to return to recreational physical activities after injury.[7]

Surgical treatment can also be costly and time consuming for a percentage of the population.

The “rule of thirds” was described by Noyes et al. in 1983, stating that at least 1/3 of patients will benefit from nonoperative treatment without instability ''giving way''[1].

For these reasons and to avoid surgical complications some patients choose to undergo conservative treatment but due to the complexity and complications of ACL-deficiency there should be some criteria to identify the right candidates for nonoperative treatment.

Screening to Identify Copers[edit | edit source]

Potential "Copers" are those who can potentially return to pivoting/cutting sports with conservative treatment.[8][9] To identify copers, a cluster of screening tests[10] was developed:


Potential copers are those who:

  • Presented without concomitant injuries: you can identify isolated ACL-injury in your subjective examination by asking about post injury swelling pattern. A two or three-hour post-injury swelling indicates an ACL injury. A delayed swelling, for instance in the following day, indicates associated chondral pathology or other injuries. Isolated ACL injuries are mostly presented with full ROM whilst restricted mobility can possibly be due to other associated injuries.
  • Achieved a minimum score of 80% limb symmetry on all hop testing
  • >80% on the KOS-ADLS,
  • >60 on the self-report of knee function
  • ≤1 subjective report of knee giving way: asking about instability after injuries. If the athlete doesn't sustain further buckling or giving way after injuries, then probably they can cope well with non-operative management.

Failure to meet all of these criteria results in a patient identified as non-coper and hence, surgery will be recommended[1].

Activity Modification[edit | edit source]

Meeting the screening tests is essential if the patient is willing to return to pivoting/cutting sports. The other option is to return to modified activity or lower load sports. A 10-year cohort followed up with ACL patients who were identified as potential copers and found very little return to sport rates among this category[15].

Sports such as football, basketball, soccer, and skiing are identified as level I/II pivoting and cutting activities requiring a high level of stability and may not be suitable for patients who chose not to undergo surgical treatment. Sedentary occupations or those who participate in less demanding sports (straight-line sporting) such as jogging and cycling have a better chance successful return to their sports with a non-operative course[1].

Rehabilitation[edit | edit source]

In the acute phase after injury, the aims of rehabilitation are restoring joint homeostasis and ROM. A patient will be presented with haemarthrosis, inhibited quads and motion deficits. To address these deficits, you can include activities such as wall slides and stationary bike to improve the joint mobility and reduce swelling. Gentle quadriceps contraction can also be introduced starting with teaching patellar glide and progressing to terminal knee extension.

Following the acute phase, exercise parameters should be adjusted to meet the following rehabilitation phases:

  • Strength
  • Power
  • Running Capacity
  • Speed and agility: starting with single-plane and progressed to multi-planes with speed to ensure returning to sports with less risk for instability.
  • Return to training
  • Return to sports

The rehabilitation frame is similar to post-operative rehabilitation which is discussed in further details in this page: ACL Rehabilitation: Rehabilitation Planning. If the athlete is keen on returning to twisting/cutting sports, Neuromuscular training should be included in the rehabilitation to restore joint stability.

Neuromuscular training[edit | edit source]

Also known as perturbation training, neuromuscular training is an essential phase in nonoperative rehabilitation with the aim of improving knee stability. Prior to starting this phase, the patient must meet the following criteria:

  • Full ROM
  • Full resolution of swelling
  • Sufficient lower limb strength

This phase can be introduced prior to building running capacity. Perturbation training comprises of a series of balance tasks with unanticipated perturbations to the unstable surface such as rocker board progressed to roller board[16]. Maintaining balance on an unstable surface with perturbation has been reported to improve knee kinematics, gait mechanics and reduced episodes of giving way[1].


Return to Sport[edit | edit source]

Completion of a series of perturbation training without any reported episodes of giving way is essential before returning to sport. In addition, demonstrating sufficient quadriceps and hamstring strength on isokinetic testing at 90% or more compared to the contralateral limb[1]. Hop tests can be used to evaluate the athlete's readiness to return to sport.

A functional performance brace is recommended when returning to pivoting/cutting sports. A reduction of anterior tibial translation and improved proprioception is believed to be the function of a functional performance brace thus, improving the sense of stability[1].

References[edit | edit source]

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Paterno MV. Non-operative care of the patient with an ACL-deficient knee. Current reviews in musculoskeletal medicine. 2017 Sep 1;10(3):322-7.
  2. Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of second ACL injuries 2 years after primary ACL reconstruction and return to sport. The American journal of sports medicine. 2014 Jul;42(7):1567-73.
  3. 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. Br J Sports Med. 2011 Jun 1;45(7):596-606.
  4. Barenius B, Ponzer S, Shalabi A, Bujak R, Norlén L, Eriksson K. Increased risk of osteoarthritis after anterior cruciate ligament reconstruction: a 14-year follow-up study of a randomized controlled trial. The American journal of sports medicine. 2014 May;42(5):1049-57.
  5. Smith TO, Postle K, Penny F, McNamara I, Mann CJ. Is reconstruction the best management strategy for anterior cruciate ligament rupture? A systematic review and meta-analysis comparing anterior cruciate ligament reconstruction versus non-operative treatment. The Knee. 2014 Mar 1;21(2):462-70.
  6. Krause M, Freudenthaler F, Frosch KH, Achtnich A, Petersen W, Akoto R. Operative Versus Conservative Treatment of Anterior Cruciate Ligament Rupture. Dtsch Arztebl Int. 2018;115(51-52):855-62.
  7. Kovalak E, Atay T, Çetin C, Atay IM, Serbest MO. Is ACL reconstruction a prerequisite for the patients having recreational sporting activities? Acta Orthop Traumatol Turc. 2018;52(1):37-43.
  8. Musahl V, Diermeier T, de Sa D, Karlsson J. "ACL surgery: when to do it?". Knee Surg Sports Traumatol Arthrosc. 2020;28(7):2023-6.
  9. Thoma LM, Grindem H, Logerstedt D, Axe M, Engebretsen L, Risberg MA et al. Coper Classification Early After Anterior Cruciate Ligament Rupture Changes With Progressive Neuromuscular and Strength Training and Is Associated With 2-Year Success: The Delaware-Oslo ACL Cohort Study. Am J Sports Med. 2019;47(4):807-14.
  10. A decision-making scheme for returning patients to high-level activity with nonoperative treatment after anterior cruciate ligament rupture
  11. Single Leg Hop for Distance _Old . Available from: [last accessed 18/09/19]
  12. Single leg Triple Hop Test for Distance . Available from:[last accessed 18/09/19]
  13. Single Hop/Crossover Hop/Triple Hop for Distance Test . Available from: [last accessed 18/09/19]
  14. Single Leg 6m Timed Hop Test. Available from:[last accessed 18/09/19]
  15. Hurd WJ, Axe MJ, Snyder-Mackler L. A 10-year prospective trial of a patient management algorithm and screening examination for highly active individuals with anterior cruciate ligament injury: part 2, determinants of dynamic knee stability. The American journal of sports medicine. 2008 Jan;36(1):48-56.
  16. Di Stasi SL, Hartigan EH, Snyder-Mackler L. Unilateral stance strategies of athletes with ACL deficiency. Journal of applied biomechanics. 2012 Aug 1;28(4):374-86.
  17. The ACL Road to Recovery - Advanced Balance and Perturbation Training . Available from: [last accessed 18/09/19]