ACL Injuries – Surgical Vs Non Surgical


ACL Injuries

Anterior cruciate ligament (ACL) injuries are common among both adolescent and adult ages, and often have large physical and psychological impacts on individuals who sustain ACL injuries.

The primary role of the ACL is preventing forward movement of the tibia (shin bone) in excessive degrees, as well as limiting rotational forces in the knee. Therefore, the ACL is an important stabilising structure for the knee. Given the important role the ACL plays in stabilising the knee and ultimately the lower limb, regaining this stability after ACL rupture is one of the most important factors when considering long term implications following ACL injury.

Following ACL injury there are two different paths that can be considered for recovery and return to pre injury levels. These approaches are surgical – which involves the reconstruction of the tendon using a tendon graft (commonly harvested from either the patients hamstring or patella tendons) or nonsurgical – which involves a comprehensive rehab program aimed at improving the strength and neuromuscular control of the knee, as well as allowing for ligament healing of the ACL.

There is growing interest in the non surgical management of ACL injuries and whether adequate knee function and stability can be regained without surgical invention. In response to this, classification has been given to different patient responses following ACL injury. Copers – can return to their pre-injury levels without surgery and without self reported instability. Adapter – reduces their level of activity to avoid any reported joint instability. Non coper – cannot return to pre-injury activity levels due to reported instability and episodes of ‘giving way’.

There are many factors that influence an individual’s classification following ACL injury, and often these can be relatively uncontrollable. However, most commonly is the neuromuscular control of the major muscle groups helping stabilise the knee. This refers to the ability to have these muscles contract quickly and effectively to stabilise the knee, acting as a dynamic ligament / dynamic stabiliser. In non surgical management following ACL injury this becomes an important consideration and it is essential to have adequate neuromuscular control for someone to be successful in non surgical management following ACL injury. The development of neuromuscular control in the muscles surrounding the knee is gained by appropriately prescribed exercises programs considering both muscle strength and speeds of muscle contraction. These exercises are specifically designed to regain instantaneous and forceful muscle contractions to support the joint. Prior to this, the individual will progress through acute management of the injury, including reducing swelling, regaining range of motion and improving muscle contractile function. Followed by improving muscle peak force values before progressing to improving the rate of force progression, which essentially gives the knee its dynamic stability.

There is no firm guarantee that each individual can function at pre-injury levels when taking part in non surgical management as this depends on many factors. Some of the most important considerations are the quality of the ligament healing and whether the ligament has been able to mend back to a fibrous tissue, as well as the individual differences that come with neuromuscular control, or potentially lack thereof. If in some cases the ACL has not been able to reattach its torn ends and there is insufficient neuromuscular control to account for this, then there may be ongoing episodes of instability experienced. If after progressing through non surgical rehab the knee still shows instability then surgical intervention may be appropriate. However, this does not mean that this rehab time has been a waste! This process can help significantly in the recovery from surgery.

More recently, research has been conducted into ways to allow the ACL to heal its torn ends and to return to a healthy, sturdy ligament. The Cross Bracing Protocol is a recently developed method for ACL healing. It involves using a brace to immobilise the knee at 90 degrees of flexion for four weeks before gradually increasing the brace settings and movement of the knee. This allows the ACL to be put into a position that is believed to be optimal for healing and to allow the torn ends of the ligament to mend back together. Following the period of bracing, the patient would then commence their physical rehabilitation without having surgery and with an intact ACL.

After acute ACL injury, 90% of those in completing the cross bracing protocol demonstrated signs of ACL healing on a three month MRI (Filbay et. al, 2003).

The Cross Bracing Protocol does involve a selective criteria for those it may be suited for and not all ACL injuries may be appropriate for cross bracing. If after an ACL injury, timely consultation with your physiotherapist is most important to determine your eligibility for cross bracing and to start the process.


Zac Turner (APAM)

Doctor of Physiotherapy, Bachelor of Education


  1. Filbay, S. R., Dowsett, M., Chaker Jomaa, M., Rooney, J., Sabharwal, R., Lucas, P., Van Den Heever, A., Kazaglis, J., Merlino, J., Moran, M., Allwright, M., Kuah, D. E., Durie, R., Roger, G., Cross, M., & Cross, T. (2023). Healing of acute anterior cruciate ligament rupture on MRI and outcomes following non-surgical management with the Cross Bracing Protocol. British Journal of Sports Medicine, 57(23), 1490–1497.
  2. Filbay, S. R., & Grindem, H. (2019). Evidence-based recommendations for the management of anterior cruciate ligament (ACL) rupture. Baillière’s Best Practice and Research in Clinical Rheumatology/Baillière’s Best Practice & Research. Clinical Rheumatology, 33(1), 33–47.
  3. Grindem, H., Wellsandt, E., Failla, M., Snyder‐Mackler, L., & Risberg, M. A. (2018). Anterior Cruciate Ligament Injury—Who succeeds without Reconstructive Surgery? The Delaware-Oslo ACL Cohort Study. Orthopaedic Journal of Sports Medicine, 6(5), 232596711877425.

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