ACL injury research samples commonly involve young athletic adults aged 18–35 years, particularly those participating in pivoting and cutting sports (Filbay et al., 2017; Porter & Shadbolt, 2025; Beard et al., 2024).
Female athletes are 1.5 times more likely to injure their ACL than male athletes (Montalvo et al., 2019).
Elite and recreational athletes demonstrate different return-to-sport expectations and recovery patterns (Feyzioğlu et al., 2020).
Typical acute presentation includes:
a mechanism of injury such as non-contact twisting or sudden deceleration, stopping, or change of direction with a fixed foot, or forceful hyperextension.
a sudden, painful popping sensation or audible pop.
significant rapid swelling (haemarthrosis developing within two hours).
pain and functional instability.
(Arumugam et al., 2021; NICE 2022, Bregenhof et al., 2023).
Subacute and post-operative presentations include:
quadriceps inhibition.
reduced range of motion.
persistent strength asymmetry.
impaired proprioception
fear of reinjury
(Chmielewski et al., 2016; Zheng et al., 2025).
Key diagnostic tests include the Lachman test, Anterior Drawer test, Pivot Shift test and Lever Sign (Bregenhof et al., 2023; Arumugam et al., 2021).
Functional performance testing, particularly single-leg hop batteries, provide objective assessment of dynamic knee control and readiness for progression (Chmielewski et al., 2016).
Limb symmetry index (LSI) of ≥90% is commonly recommended prior to RTS, although this should be interpreted alongside movement quality and sport-specific demands (Zheng et al., 2025). Isokinetic or handheld dynamometry is used to quantify quadriceps and hamstring deficits, which are strong predictors of reinjury risk (Feyzioğlu et al., 2020).
Psychological readiness screening is essential, as fear avoidance and low confidence negatively influence functional outcomes (Zebis et al., 2019).
ACL injuries rarely occurs in isolation. Bone bruising is very common. Other structures frequently injured include the medial meniscus and the MCL. Injuries to the lateral meniscus, LCL, joint cartilage and associated fractures can also accompany ACL injury (Cristiani et al., 2024).
Differential diagnoses following traumatic knee injury include meniscal tears, collateral or cruciate ligament injury, posterolateral corner injury, tibial plateau fracture, patellar dislocation, and focal cartilage lesions, all of which should be considered during assessment (Matthewson et al., 2021; Filbay et al., 2017; Porter & Shadbolt, 2025).
Red flags include traumatic haemarthrosis (Porter & Shadbolt, 2025), inability to weight-bear (Chmielewski et al., 2016), and indicators of infection, both local and systemic (Bregenhof et al., 2023).
ACL literature distinguishes between:
accelerated versus standard rehabilitation protocols (Beard et al., 2024),
supervised versus home-based rehabilitation models (Carter et al., 2021),
and the use of
progressive resistance and neuromuscular training (Arumugam, A. et al. (2021).
Return-to-sport criteria and the ACL-RSI scale are widely used to assess functional and psychological readiness (Filbay et al., 2017).
ACLR = ACL Reconstruction.
Lateral Extra-articular Tenodesis (LET) and Anterolateral Ligament Reconstruction (ALLR) are surgical procedures often used alongside standard ACLR to improve knee rotational stability and reduce the risk of graft failure.
Whilst physiotherapy oversight is recommended during ACLR rehabilitation, the number or frequency of supervised sessions does not appear to significantly affect outcomes. Physiotherapy should focus on education to support independence with rehabilitation, ensuring patients are competent performing their exercises and are able to identify warning signs such as increased pain and swelling. Shared Decision Making (SDM) should be implemented to ensure effective individualised care. Supervised sessions should be offered as required / based on individual patient need (Gamble et al., 2021).
Prehabilitation (prehab):
Focused prehab can help manage the acute stage of injury, improve knee function (ROM and strength) and address associated psychosocial issues. It can improve quality of life for patients awaiting or considering ACLR and may improve long term post-operative outcomes including return to sport (Alshewaier et al. 2016, Granicher and Scherr, 2021).
Open and closed chain exercise:
A systematic review by Luque-Seron and Medina-Porqueres (2016) comparing ACL strain during Open Chain (OC) and Closed Chain (CC) exercises found that the strain values produced by both types of exercises are similar. However, it was noted that applying external resistance during OC exercises increases strain values whilst this is not the case with CC exercises, where strain values did not increase significantly in response to increased compressive load.
Plyometrics:
Plyometric exercise improves knee function and psychosocial status post ACLR (Elias et al., 2018, Chmielewski et al., 2016).
Buckthorpe and Della Villa (2021) provide a comprehensive 4 stage plyometric rehab. programme for ACLR patients (see below).
Proprioceptive and functional training:
The inclusion of proprioceptive training in the rehabilitation of ACL deficient or post op ACLR patients improves knee function, dynamic balance and psychological readiness (Zheng et al., 2025, Arumugam et al., 2021).
The inclusion of functional training can significantly aid proprioceptive recovery, neuromuscular control and range of movement during the early post-operative stage (Chuanjia et al., 2024).
Emerging evidence:
Blood Flow Restriction training may be an effective rehabilitation adjunct during the early post-operative phase following ACL reconstruction (Hughes et al., 2019). Please note BFR is currently not employed in NSHGGC.
Surgical versus non-surgical management:
The ACL SNNAP trial by Beard et al. (2022) showed that although benefit can still be obtained from initial non-surgical treatment, ACLR had superior outcomes when compared with non-surgical management after 18 months. Porter and Shadbolt (2025) found that ACLR resulted in a significantly lower risk of recurrent instability and meniscal tears, and improved outcomes when compared with non-operative management over a 3 year period.
Early versus delayed surgical intervention:
The KANON trial found that delaying ACLR and managing initially with exercise therapy can positively affect prognosis by allowing the acute stage of the injury to settle (Filbay et al., 2017). A review by Matthewson et al. (2021) found that delaying ACLR (until 4-12 weeks post injury) did not increase the incidence of meniscal or chondral lesions of the knee. It also did not negatively affect post–op outcomes including ROM, activity level or knee stability.
Relevant biopsychosocial factors:
The below biopsychosocial factors have all been associated with inferior post operative outcomes:
meniscal injury, +/- meniscal intervention, full thickness cartilage damage.
psychological issues including external locus of control, reduced knee self-efficacy and fear of re-injury.
smoking and low education levels.
(Filbay et al., 2017).
In acute suspected ACL (often not seen in msk acutely):
May warrant XR imaging in first instance to rule out osteochondral defect (particularly if increased force involved and/ or significant haemarthrosis indicated)
If suspect ACL injury on testing:
Gold standard investigation for diagnosis ACL rupture is MRI; options for imaging via
Primary Care- GP/ Primary Care APP's have rights for MRI knee in individuals <60 who have indications of instability
MSK APP staff can also arrange for MRI for appropriate patients- follow referral guidance to request review
via orthopaedic referral
If suspect re-rupture/ new injury to ACLR when attending for rehab
contact consultant / relevant ortho knee ESP to discuss
Ortho ESP staff have advised if chronic ACL tear/ reconstruction and knee pain in patients > 40 years old consider applicability of XR to grade degree of OA change
Escalation of care should be considered in the presence of persistent subjective instability, recurrent giving-way, ongoing mechanical symptoms such as locking, failure to achieve ≥90% strength or hop-test symmetry or significant psychological barriers to rehabilitation (Gamble et al., 2021; Coronado et al., 2020).
Referral for orthopaedic review, enhanced psychological support, or more intensive supervised rehabilitation may be required to optimize outcomes.
Other guidelines for possible interest:
Plyometric resource:
Buckthorpe and Della Villa 2021 - plyometric rehab. programme
Psychological readiness resource:
ACL-RSI | PDF & Online Calculator
Mick Hughes blogs:
4 Pillars of Better ACL Rehab - by Mick Hughes
Stop Waiting, Start Loading. - by Mick Hughes - The ACL Hub
Stronger After ACL Surgery? Absolutely! - by Mick Hughes
Late Stage ACLR Rehab - by Mick Hughes - The ACL Hub
Alshewaier, S., Yeowell, G. & Fatoye, F. (2017) The effectiveness of pre-operative exercise physiotherapy rehabilitation on ACL outcomes: a systematic review. Clinical Rehabilitation, 31, pp. 34–44. Available at: https://doi.org/10.1177/0269215516628617
Arumugam, A. et al. (2021) Effects of neuromuscular training on knee proprioception in individuals with ACL injury: a systematic review and GRADE evidence synthesis. BMJ Open, e049226. Available at: https://doi.org/10.1136/bmjopen-2021-049226
Ashour, A.A. et al. (2024) Crossover knee and ankle joint training on knee mechanics after ACLR: RCT. Gait & Posture, 113, pp. 512–518. Available at: https://doi.org/10.1016/j.gaitpost.2024.08.011
Beard, D.J. et al. (2024) ACL SNNAP RCT – surgical vs non-surgical management for non-acute ACL injury. Health Technology Assessment, 28, pp. 1–97. Available at: https://doi.org/10.3310/VDKB6009
Bregenhof, B.O. et al. (2023) Progressive resistance exercise and persistent hamstring deficit after ACLR: RCT. JOSPT, 53, pp. 40–48. Available at: https://doi.org/10.2519/jospt.2022.11360
Buckthorpe, M. and Della Villa, F., 2021. Recommendations for plyometric training after ACL reconstruction–A clinical commentary. International journal of sports physical therapy, 16(3), p.879.
Carter, H.M. et al. (2021) Preoperative physiotherapy strategies worldwide: survey. Knee, 28, pp. 300–310. Available at: https://doi.org/10.1016/j.knee.2020.12.018
Chao, W. et al. (2018) Functional movement training after ACLR: RCT. Journal of Sport Rehabilitation, 27, pp. 541–545. Available at: https://doi.org/10.1123/jsr.2017-0022
Chmielewski, T.L. et al. (2016) Low vs high intensity plyometric exercise after ACLR. American Journal of Sports Medicine, 44, pp. 609–617. Available at: https://doi.org/10.1177/0363546515620583
Chuanjia, D.U. et al. (2024) Three-month functional training improves joint function post-ACLR. Journal of Rehabilitation Medicine, 56:1–10. Available at: https://doi.org/10.2340/jrm.v56.18701
Coronado, R.A. et al. (2020) Cognitive-behavioural-based PT to improve RTS after ACLR. Physical Therapy in Sport, 42, pp. 82–90. Available at: https://doi.org/10.1016/j.ptsp.2020.01.004
Cristiani, R., van de Bunt, F., Kvist, J., & Stålman, A. (2024). High prevalence of associated injuries in anterior cruciate ligament tears: A detailed magnetic resonance imaging analysis of 254 patients. Skeletal Radiology, 53, 2417–2427. https://doi.org/10.1007/s00256-024-04665-9
Elias, A.R.C. et al. (2018) Jump training with BW support after ACLR: RCT. American Journal of Sports Medicine, 46, pp. 1650–1660. Available at: https://doi.org/10.1177/0363546518759052
Feyzioğlu, Ö. et al. (2020) Accelerated programme outcomes in elite athletes vs non-athletes. Journal of Sport Rehabilitation, 29, pp. 572–575. Available at: https://doi.org/10.1123/jsr.2018-0346
Filbay, S.R. et al. (2017) Effect of delaying ACLR on 5-year prognosis: exploratory KANON trial. BJSM, 51, 1622–1629. Available at: https://doi.org/10.1136/bjsports-2016-097124
Gamble, A.R. et al. (2021) Supervised vs less supervised rehab after ACLR: meta-analysis. J Sci Med Sport, 24, pp. 862–870. Available at: https://doi.org/10.1016/j.jsams.2021.03.003
Granicher, P. & Scherr, J. (2021) Do athletes benefit from pre-operative PT? Sport Orthop Traumatol, 37, pp. 126–131. Available at: https://doi.org/10.1016/j.orthtr.2021.04.038
Hughes, L. et al. (2019a) Comfort and pain with BFR rehab after ACLR. Phys Ther Sport, 39, pp. 90–98. Available at: https://doi.org/10.1016/j.ptsp.2019.06.014
Hughes, L. et al. (2019b) BFR vs heavy resistance post-ACLR: RCT. Sports Medicine, 49, pp. 1787–1805. Available at: https://doi.org/10.1007/s40279-019-01137-2
Luque-Seron, J.A. & Medina-Porqueres, I. (2016) ACL strain review. Sports Health, 8, pp. 451–455. Available at: https://doi.org/10.1177/1941738116658006
Matthewson, G. et al. (2021) Delay to ACLR and incidence of secondary pathology: SR & meta-analysis. Clin J Sport Med, 31, pp. 313–320. Available at: https://doi.org/10.1097/JSM.0000000000000762
Montalvo, A.M., Schneider, D.K., Yut, L., Webster, K.E., Beynnon, B., Kocher, M.S. and Myer, G.D., 2019. “What’s my risk of sustaining an ACL injury while playing sports?” A systematic review with meta-analysis. British journal of sports medicine, 53(16), pp.1003-1012. Available at: 1003.full.pdf
National Institute for Health and Care Excellence (NICE) (2022) Knee pain – assessment: traumatic causes. NICE Clinical Knowledge Summaries (CKS). Available at: https://cks.nice.org.uk/topics/knee-pain-assessment/diagnosis/traumatic-causes/ (Accessed: 28 July 2026).
Porter, M.D. & Shadbolt, B. (2025) Surgical vs non-operative ACL rupture outcomes: 3-year cohort study. Orthopaedic Journal of Sports Medicine, 13, pp. 1–9. Available at: https://doi.org/10.1177/23259671251320647
Zebis, M.K. et al. (2019) EMG evaluation of rehabilitation progression post-ACL injury. Am J Phys Med Rehabil, 98, pp. 998–1004. Available at: https://doi.org/10.1097/PHM.0000000000001232
Zheng, Q. et al. (2025) Proprioceptive training post-ACLR: RCT. BMC Musculoskeletal Disorders, 26:364. Available at: https://doi.org/10.1186/s12891-025-08621-z
GGC - MSK Index