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  • Writer's picturePaul Monaro

'Prehabilitation' after ACL Injury

When a patient is given a diagnosis of ACL rupture or booked for ACL reconstructive surgery (ACLR), it is essential that they undertake a preoperative rehabilitation programme. There are several studies that highlight the implications this has for the patient’s long-term success.

Surgeons have different approaches to the timing of knee surgery. Some recommended early surgery – based on the earliest time available for surgeon and patient. Others, generally the more experienced surgeons, recommend a delay of at least six weeks to allow tissue healing and an adequate rehabilitation period (7).

Numerous studies have shown worse outcomes with surgery performed in the weeks immediately after an ACL injury. It is recognised that there is a high risk of developing postoperative arthrofibrosis if surgery is undertaken on an acutely inflamed and swollen knee. This finding was verified by several authors in a 2014 systematic review (4). The overall recommendation was that the timing of surgery should be based on when the patient has minimal to no swelling and has regained adequate strength and a full range of motion (4,7).

Preoperative strength has been shown to have a significant impact on the patient’s success in regaining strength postoperatively. The better the improvements in quadriceps strength, the better the function for at least two years post-ACLR. In one study, quadriceps deficits of 20% or more preoperatively led to persistent large strength deficits at two years post-ACLR (2). Quadriceps deficits are greatest in the first few weeks after injury when there is persistent pain and swelling. Swelling has been shown to be a powerful inhibitor of quadriceps function due to arthrogenic muscle inhibition (8,9), with peak knee extensor torque decreasing up to 75% within the first few days and taking several weeks to recover (8).

Better preoperative function has been linked with superior outcomes many years after surgery. In one study, patients were assessed on quality of life and overall knee function, both preoperatively and for up to 6 years postoperatively (6). It was found that those who had better function and quality of life preoperatively had significantly better outcomes and function for the entire duration of the study period (6).

A 2016 controlled study followed patients for 2 years postoperatively (5). The study group had 10 sessions of preoperative physiotherapy over 5 weeks, while the control group had standard care. The study group had significantly higher rates of return to sport at 2 years. They also scored significantly better for symptomatology, quality of life, and ability to engage in recreation and activities of daily living (1,5).

A 2010 study looked at functional improvement in a group of 100 patients who underwent a 10-week preoperative programme. The rehabilitation consisted of aerobic exercises, strength training (heavy resistance), plyometric exercises, balance/stability exercises, and perturbation training. Measurements of hamstring and quadriceps strength, hop tests, and self-perceived function improved significantly in 96% of subjects (3). 36% did so well they decided to forego surgery at the end of the programme (3).

There is no urgency to progress to surgery after an ACL injury. Patients recover well from the acute trauma, and generally regain normal function for activities of daily living within a few weeks. The risk of further injury during this time is low. While the patient recovers and undertakes valuable rehabilitation, they can take their time deciding on the best longer-term management.


1. Alshewaier, S et al (2017). The effectiveness of preoperative physiotherapy rehabilitation on outcomes of treatment following ACL injury: a systematic review. Clin. Rehabilitation, 31, 1, 34-44.

2. Eitzen, I et al (2009). Preoperative quadriceps strength is a significant predictor of knee function two years after ACL reconstruction. British Journal of Sports Medicine, 43, 5, 371-376.

3. Eitzen, I et al (2010). A progressive 5-week exercise therapy programme leads to significant improvements in knee function early after ACL injury. JOSPT, 40, 11, 705-721.

4. Evans, S et al (2014). ACL reconstruction – it’s all about timing. International Journal of Sports Physical Therapy, 9, 2, 268-273.

5. Fallia, M et al (2016). Does extended preoperative rehabilitation influence outcomes 2 years after ACL reconstruction? A comparative effectiveness study between the MOON & Delaware-Oslo ACL cohorts. AJSM, 44, 10, 2608-2614.

6. Mansson, O et al (2013). Preoperative factors predicting good outcome in terms of health-related quality of life after ACL reconstruction. Scand. J. Science & Med in Sport, 23, 1, 15-22.

7. Pinczewski et al (2020). ACL rehabilitation protocol. North Sydney Orthopaedic & Sports Medicine Centre.

8. Shakespeare, D et al (1985). Reflex inhibition of the quadriceps after meniscectomy: lack of association with pain. Clinical Physiology, 5, 137-144.

9. Spencer J, et al (1984). Knee joint effusion and quadriceps reflex inhibition in man. Arch. Phys Med & Rehab, 65, 171-177.

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