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

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.