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. 2024 Jun;28(27):1–97. doi: 10.3310/VDKB6009

Comparison of surgical or non-surgical management for non-acute anterior cruciate ligament injury: the ACL SNNAP RCT.

David J Beard, Loretta Davies, Jonathan A Cook, Jamie Stokes, Jose Leal, Heidi Fletcher, Simon Abram, Katie Chegwin, Akiko Greshon, William Jackson, Nicholas Bottomley, Matthew Dodd, Henry Bourke, Beverly A Shirkey, Arsenio Paez, Sarah E Lamb, Karen L Barker, Michael Phillips, Mark Brown, Vanessa Lythe, Burhan Mirza, Andrew Carr, Paul Monk, Carlos Morgado Areia, Sean O'Leary, Fares Haddad, Chris Wilson, Andrew Price; ACL SNNAP Study Group
PMCID: PMC11228690  PMID: 38940695

Abstract

BACKGROUND

Anterior cruciate ligament injury of the knee is common and leads to decreased activity and risk of secondary osteoarthritis of the knee. Management of patients with a non-acute anterior cruciate ligament injury can be non-surgical (rehabilitation) or surgical (reconstruction). However, insufficient evidence exists to guide treatment.

OBJECTIVE(S)

To determine in patients with non-acute anterior cruciate ligament injury and symptoms of instability whether a strategy of surgical management (reconstruction) without prior rehabilitation was more clinically and cost-effective than non-surgical management (rehabilitation).

DESIGN

A pragmatic, multicentre, superiority, randomised controlled trial with two-arm parallel groups and 1:1 allocation. Due to the nature of the interventions, no blinding could be carried out.

SETTING

Twenty-nine NHS orthopaedic units in the United Kingdom.

PARTICIPANTS

Participants with a symptomatic (instability) non-acute anterior cruciate ligament-injured knee.

INTERVENTIONS

Patients in the surgical management arm underwent surgical anterior cruciate ligament reconstruction as soon as possible and without any further rehabilitation. Patients in the rehabilitation arm attended physiotherapy sessions and only were listed for reconstructive surgery on continued instability following rehabilitation. Surgery following initial rehabilitation was an expected outcome for many patients and within protocol.

MAIN OUTCOME MEASURES

The primary outcome was the Knee Injury and Osteoarthritis Outcome Score 4 at 18 months post randomisation. Secondary outcomes included return to sport/activity, intervention-related complications, patient satisfaction, expectations of activity, generic health quality of life, knee-specific quality of life and resource usage.

RESULTS

Three hundred and sixteen participants were recruited between February 2017 and April 2020 with 156 randomised to surgical management and 160 to rehabilitation. Forty-one per cent (n = 65) of those allocated to rehabilitation underwent subsequent reconstruction within 18 months with 38% (n = 61) completing rehabilitation and not undergoing surgery. Seventy-two per cent (n = 113) of those allocated to surgery underwent reconstruction within 18 months. Follow-up at the primary outcome time point was 78% (n = 248; surgical, n = 128; rehabilitation, n = 120). Both groups improved over time. Adjusted mean Knee Injury and Osteoarthritis Outcome Score 4 scores at 18 months had increased to 73.0 in the surgical arm and to 64.6 in the rehabilitation arm. The adjusted mean difference was 7.9 (95% confidence interval 2.5 to 13.2; p = 0.005) in favour of surgical management. The per-protocol analyses supported the intention-to-treat results, with all treatment effects favouring surgical management at a level reaching statistical significance. There was a significant difference in Tegner Activity Score at 18 months. Sixty-eight per cent (n = 65) of surgery patients did not reach their expected activity level compared to 73% (n = 63) in the rehabilitation arm. There were no differences between groups in surgical complications (n = 1 surgery, n = 2 rehab) or clinical events (n = 11 surgery, n = 12 rehab). Of surgery patients, 82.9% were satisfied compared to 68.1% of rehabilitation patients. Health economic analysis found that surgical management led to improved health-related quality of life compared to non-surgical management (0.052 quality-adjusted life-years, p = 0.177), but with higher NHS healthcare costs (£1107, p < 0.001). The incremental cost-effectiveness ratio for the surgical management programme versus rehabilitation was £19,346 per quality-adjusted life-year gained. Using £20,000-30,000 per quality-adjusted life-year thresholds, surgical management is cost-effective in the UK setting with a probability of being the most cost-effective option at 51% and 72%, respectively.

LIMITATIONS

Not all surgical patients underwent reconstruction, but this did not affect trial interpretation. The adherence to physiotherapy was patchy, but the trial was designed as pragmatic.

CONCLUSIONS

Surgical management (reconstruction) for non-acute anterior cruciate ligament-injured patients was superior to non-surgical management (rehabilitation). Although physiotherapy can still provide benefit, later-presenting non-acute anterior cruciate ligament-injured patients benefit more from surgical reconstruction without delaying for a prior period of rehabilitation.

FUTURE WORK

Confirmatory studies and those to explore the influence of fidelity and compliance will be useful.

TRIAL REGISTRATION

This trial is registered as Current Controlled Trials ISRCTN10110685; ClinicalTrials.gov Identifier: NCT02980367.

FUNDING

This award was funded by the National Institute of Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 14/140/63) and is published in full in Health Technology Assessment; Vol. 28, No. 27. See the NIHR Funding and Awards website for further award information.

Plain language summary

The study aimed to find out whether it is better to offer surgical reconstruction or rehabilitation first to patients with a more long-standing injury of their anterior cruciate ligament in their knee. This injury causes physical giving way of the knee and/or sensations of it being wobbly (instability). The instability can affect daily activities, work, sport and can lead to arthritis. There are two main treatment options for this problem: non-surgical rehabilitation (prescribed exercises and advice from physiotherapists) or an operation by a surgeon to replace the damaged ligament (anterior cruciate ligament reconstruction). Although studies have highlighted the best option for a recently injured knee, the best management was not known for patients with a long-standing injury, perhaps occurring several months previously. Because the surgery is expensive to the NHS (around £100 million per year), it was also important to look at the costs involved. We carried out a study recruiting 316 non-acute anterior cruciate ligament-injured patients from 29 different hospitals and allocated each patient to either surgery or rehabilitation as their treatment option. We measured how well they did with special function and activity scores, patient satisfaction and costs of treatment. Patients in both groups improved substantially. It was expected that some patients in the rehabilitation group would want surgery if non-surgical management was unsuccessful. Forty-one per cent of patients who initially underwent rehabilitation subsequently elected to have reconstructive surgery. Overall, the patients allocated to the surgical reconstruction group had better results in terms of knee function and stability, activity level and satisfaction with treatment than patients allocated to the non-operative rehabilitation group. There were few problems or complications with either treatment option. Although the surgery was a more expensive treatment option, it was found to be cost-effective in the UK setting. The evidence can be discussed in shared decision-making with anterior cruciate ligament-injured patients. Both strategies of management led to improvement. Although a rehabilitation strategy can be beneficial, especially for recently injured patients, it is advised that later-presenting non-acute and more long-standing anterior cruciate ligament-injured patients undergo surgical reconstruction without necessarily delaying for a period of rehabilitation.

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