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Research Review By Dr. Joshua Plener©


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Date Posted:

March 2023

Study Title:

Primary surgery versus primary rehabilitation for treating anterior cruciate ligament injuries: a living systematic review and meta-analysis


Saueressig T, Braun T, Steglich N, et al.

Author's Affiliations:

Science and Research, Physio Meets Science GmbH, Leimen, Baden-Wurttemberg, Germany; Department of Applied Health Sciences, Division of Physiotherapy, Hochschule fur Gesundheit, Bochum, North Rhine-Westphalia, Germany; HSD Hochschule Dopfer, Cologne, North Rhine-Westphalia, Germany

Publication Information:

British Journal of Sports Medicine 2022; 56: 1241-1251.

Background Information:

Anterior cruciate ligament (ACL) injuries are one of the most common and serious knee injuries. There is an ongoing clinical and scientific debate that certainly matters to our patients – whether the management of these injuries should primarily consist of surgery or rehabilitation (1-4)? Currently, the quality of evidence from existing randomized trials (RCTs) cannot provide an answer as to which approach is superior. From a patient’s perspective, the experience with these two interventions can be drastically different, so it would be nice to be able to offer some evidence-based advice!

The aim of this living systematic review is to examine the comparative effectiveness of surgery versus rehabilitation treatments after an ACL rupture. A living systematic review, as defined by the Cochrane Library, is a systematic review which is continually updated, incorporating relevant new evidence as it becomes available. This approach is useful for this topic as it is expected that the evidence base for the outcomes assessed in this review will evolve over time. The authors plan to update this review every year for a minimum of 6 years.

Pertinent Results:

Literature Search:
From the literature search, 9514 articles were identified. After removing duplicates and screening titles and abstracts, 104 full text articles were assessed and three studies (320 subjects in total) were included (5-7). The sample sizes ranged from 32 to 167 participants and the average age of all participants was 29.5 years. Two study outcomes were rated as low risk of bias overall and the other study outcomes were rated as some concerns or a high risk of bias overall. The certainty of evidence was generally rated as low or very low certainty.

In the short and medium-term, there was no statistical difference between surgery or rehabilitation for self-reported knee function, as well as no clinically meaningful findings identified. These findings were rated as low certainty of evidence.

One study reported on the development of new or worsening meniscal damage and found that there was no difference between early surgery compared with primary rehabilitation at long-term follow-up, which was rated as low certainty of evidence.

Two studies assessed the occurrence of radiographical knee osteoarthritis and the authors found no statistically significant effect at long term follow-up between the two treatments. This evidence was rated as very low level of certainty.

Two studies assessed health-related quality of life and found no effect for early surgery compared to rehabilitation at the medium term follow-up. This evidence was rated as low level of certainty.

One study reported on the number of patients with any meniscal surgery during the study and found that there was no difference observed in individuals receiving surgery compared to rehabilitation. This evidence was rated as low level of certainty.

All studies assessed self-reported return to activity and found that at medium to long-term follow-ups, there was no difference between the two treatments. This finding was rated as very low certainty of evidence.

Clinical Application & Conclusions:

This living systematic review (which currently includes three studies with 320 total subjects) found that there is very low to low certainty of evidence that there are no clinically relevant differences in most outcomes between early surgical reconstruction of an ACL rupture and primary rehabilitation with optional reconstruction. With regards to improving knee function, more than 90% of patients achieve the minimally clinically important difference on the Knee Injury and Osteoarthritis Outcome Score scales after 2 years, regardless of the treatment. Therefore, the current evidence suggests that both early surgery and primary rehabilitation result in clinically meaningful improvements in the long term for subjective knee function.

Early ACL reconstruction did not show any protective effects on the development of post traumatic osteoarthritis. In fact, this review showed a trend for less cartilage loss when receiving primary rehabilitative therapy and/or delayed reconstruction. This challenges the historical paradigm that anatomical instability must be stabilized with surgery in order to prevent knee osteoarthritis. As well, this supports the notion that posttraumatic osteoarthritis is a complex and multifactorial process and the prevention of degenerative cartilage damage by surgical or conservative treatments doesn’t seem possible.

With regards to the occurrence of meniscal surgery, there is no statistically significant difference between early surgery and primary rehabilitation, which was rated as low certainty of evidence. However, the analysis did indicate that the observed differences that the authors found were primarily due to delayed ACL reconstruction. Therefore, early ACL reconstruction in patients with functional instability may be sensible, as the analysis in this review demonstrated less favourable meniscal health for delayed surgery. As it is best practice to operate on unstable knees (8), it is suggested that in the case of functional instability of the knee, a surgical reconstruction of that knee is warranted.

When considering a return to activity, in the medium to long term, there was no difference found between groups, which was rated as very low certainty of evidence. The current expert recommendations are that athletes with a high functional demand should undergo surgical treatment. However, this recommendation is based on low quality evidence and future RCTs will help provide clarity to this clinical scenario.

Overall, there appear to be no clinically meaningful differences between treatment approaches and therefore individualized and patient centered care is needed. Depending on the medical situation and individual anatomical differences, functional demands in daily life or sports, a shared decision process should be undertaken in order to identify the best treatment option for the patient. It appears that for ACL injuries without serious concomitant injuries, a stepped care approach with a rehabilitation focus first seems appropriate. Despite the lack of high quality evidence, it is suggested that functional instability should be treated surgically in order to minimize secondary joint damage. Future research should work to develop and validate a treatment algorithm and clinical decision making process. Moving forward, RCTs with longer follow-ups are necessary and assessing and developing a best practice recommendation is critically important.

Study Methods:

An electronic database search of MEDLINE, EMBASE, CINAHL, Web of Science Core Collection, CENTRAL and SPORTDiscus was conducted from inception to June, 2022. There were no language restrictions to the searches and two independent reviewers evaluated all the trials based on their title and abstracts, and subsequent full texts.

The inclusion criteria were:
  • Participants of any age with an ACL rupture.
  • The interventions of interest were reconstructive surgery of the ACL with any method and technique, and the comparator groups were rehabilitation interventions with or without delayed surgical reconstruction of the ACL.
  • The primary outcomes measured were self-reported knee function, radiological osteoarthritis, and meniscal injuries at all follow-ups. The secondary outcomes were adverse events, health related quality of life, return to activity or level of sport participation, functional assessments, knee stability and objective measures of muscle strength.
  • Study designs that were included were parallel randomized controlled trials.
The risk of bias was assessed using the Cochrane Risk of Bias Tool version 2 (9), with two independent assessors performing the assessment. Furthermore, the certainty of evidence was assessed using GRADE.

Effect size measurements were determined using standardized mean differences to determine small, medium or large effect sizes. The International Knee Documentation Committee Questionnaire for patient-reported knee scores was used as a measure of the minimally clinically important difference (MCID) (10). The MCID values used were 16.7 points for short-term, 17 points for medium-term, and 17 points for long-term (10).

Study Strengths / Weaknesses:

  • This systematic review was conducted with rigorous methodology.
  • As a living systematic review, it will be updated every year, ensuring that the latest evidence is incorporated into the results.
  • There were a low number of included studies which led to a lot of uncertainties regarding the best treatment approach for ACL ruptures. This is a weakness of the literature and not the systematic review itself.
  • The only MCIDs that were specified were for self-reported knee function and not for any other outcomes, making it difficult to assess clinically relevant differences.

Additional References:

  1. Filbay SR, Grindem H. Evidence-Based recommendations for the management of anterior cruciate ligament (ACL) rupture. Best Pract Res Clin Rheumatol 2019; 33: 33–47.
  2. Zadro JR, Pappas E. Time for a different approach to anterior cruciate ligament injuries: educate and create realistic expectations. Sports Med 2019; 49: 357–63.
  3. Diermeier TA, Rothrauff BB, Engebretsen L, et al. Treatment after ACL injury: panther symposium ACL treatment consensus group. Br J Sports Med 2021; 55: 14–22.
  4. Paschos NK, Howell SM. Anterior cruciate ligament reconstruction: principles of treatment. EFORT Open Rev 2016; 1: 398–408.
  5. Tsoukas D, Fotopoulos V, Basdekis G, et al. No difference in osteoarthritis after surgical and non-surgical treatment of ACL-injured knees after 10 years. Knee Surg Sports Traumatol Arthrosc 2016; 24: 2953–9.
  6. Reijman M, Eggerding V, van Es E, et al. Early surgical reconstruction versus rehabilitation with elective delayed reconstruction for patients with anterior cruciate ligament rupture: compare randomised controlled trial. BMJ 2021; 372: n375.
  7. Frobell RB, Roos EM, Roos HP, et al. A randomized trial of treatment for acute anterior cruciate ligament tears. N Engl J Med 2010; 363: 331–42.
  8. Diermeier T, Rothrauff BB, Engebretsen L, et al. Treatment after anterior cruciate ligament injury: panther symposium ACL treatment consensus group. Knee Surg Sports Traumatol Arthrosc 2020; 28: 2390–402.
  9. Sterne JAC, Savović J, Page MJ, et al. Rob 2: a revised tool for assessing risk of bias in randomised trials. BMJ 2019; 366: l4898.
  10. Celik D, Coban, Kilicoglu O. Minimal clinically important difference of commonly used hip-, knee-, foot-, and ankle-specific questionnaires: a systematic review. J Clin Epidemiol 2019; 113: 44–57.

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