The anterior cruciate ligament (ACL) runs obliquely through the middle of the knee and plays a roll in stabilising the joint. Sports that involve rapid change in direction, pivoting, side stepping, sudden stops, jumping and landing, or physical contact, can all place stress on the ACL. Some sports that have a higher risk of ACL injury are: skiing, soccer, AFL, rugby league, rugby union, touch football, Oz tag, netball, basketball, martial arts, mountain biking, motor cross, and gymnastics.
Studies show the annual rate of ACL rupture in Australia is 0.05% per person per year. Professional athletes in basketball, soccer, and the other football codes report an annual incidence of 0.15%–3.7% (ref).
Female athletes tear their ACL at a higher rate than males, with a frequency of two to eight times higher depending on the sport. The increased risk is attributed to differences in anatomy, muscle strength, and hormonal influences (ref).
For athletes younger than 25 who return to high-risk sport, the incidence of recurrent ACL injury after reconstructive surgery is 23% (ref).
Studies show the annual rate of ACL rupture in Australia is 0.05% per person per year. Professional athletes in basketball, soccer, and the other football codes report an annual incidence of 0.15%–3.7% (ref).
Female athletes tear their ACL at a higher rate than males, with a frequency of two to eight times higher depending on the sport. The increased risk is attributed to differences in anatomy, muscle strength, and hormonal influences (ref).
For athletes younger than 25 who return to high-risk sport, the incidence of recurrent ACL injury after reconstructive surgery is 23% (ref).
HAVE I RUPTURED MY ACL?
Symptoms will vary depending on how severely the ACL has been injured and also the other possible associated injuries sustained in the accident.
Symptoms may include (but not always):
If you think you have injured your ACL:
A damaged ACL may involve a partial or complete tear of the ligament. A mild injury may stretch the ligament but leave it intact. If an ACL injury is suspected, your doctor or physiotherapist will refer you for an MRI (Magnetic Resonance Imaging) scan, which will provide detailed images of inside the knee. The MRI should take place within the first few days after injury. The MRI will allow a doctor to determine where and how badly you have injured the knee. You may also need an X-ray to rule out any bone fracture(s).
Symptoms will vary depending on how severely the ACL has been injured and also the other possible associated injuries sustained in the accident.
Symptoms may include (but not always):
- Feeling the knee “giving way”
- Hearing a “snap" or “pop"
- Instant pain followed by swelling
- Feeling of ongoing instability
- Pain with weight bearing
- Pain and stiffness with full flexion (bending) and extension (straightening).
If you think you have injured your ACL:
- First-aid instructions are here
- Range of Motion brace set to 30°-90°
- NWB on crutches
- Arrange for an "emergency" X-ray and MRI, specifically requesting a full sequence / double oblique sequence
with slices no greater than 3mm. PRP Radiology at The Stadium Clinic reserve emergency MRI slots for ACL ruptures. - If in pain, use paracetamol. Avoid anti-inflammatories (NSAIDS) such as Nurofen.
A damaged ACL may involve a partial or complete tear of the ligament. A mild injury may stretch the ligament but leave it intact. If an ACL injury is suspected, your doctor or physiotherapist will refer you for an MRI (Magnetic Resonance Imaging) scan, which will provide detailed images of inside the knee. The MRI should take place within the first few days after injury. The MRI will allow a doctor to determine where and how badly you have injured the knee. You may also need an X-ray to rule out any bone fracture(s).
TREATMENT OPTIONS
After ACL rupture, you can choose the treatment pathway most suited to your particular injury and circumstances. This includes surgical and non-surgical treatment options. Whatever pathway you chose, the aim is to restore functional stability to the knee and return safely to your preferred activities, and importantly, reduce the risk of sustaining another ACL injury.
Following acute injury to the ACL there have traditionally been two main treatment options, (1) surgery or (2) non-surgical rehabilitation. There is more recently a third option, the ACL Cross Bracing Protocol.
1. ACL RECONSTRUCTION SURGERY
In North America, Europe, and Australia, most ACL ruptures are treated with ACL reconstruction (ACLR) and the rate of ACLR is increasing. ACL reconstruction, using graft material from the patient or a donor, has been practiced for decades, is well understood, and offers reliable results.
Reconstruction uses either hamstring tendons or a part of the patella tendon as graft material. This is fixed in place at the origin and insertion of the patient’s ACL. The procedure requires the removal of any remaining ACL tissue and the points of fixation of the graft material do not exactly match the pattern of attachment that the native ACL enjoyed.
Advantages:
Disadvantages:
After ACL rupture, you can choose the treatment pathway most suited to your particular injury and circumstances. This includes surgical and non-surgical treatment options. Whatever pathway you chose, the aim is to restore functional stability to the knee and return safely to your preferred activities, and importantly, reduce the risk of sustaining another ACL injury.
Following acute injury to the ACL there have traditionally been two main treatment options, (1) surgery or (2) non-surgical rehabilitation. There is more recently a third option, the ACL Cross Bracing Protocol.
1. ACL RECONSTRUCTION SURGERY
In North America, Europe, and Australia, most ACL ruptures are treated with ACL reconstruction (ACLR) and the rate of ACLR is increasing. ACL reconstruction, using graft material from the patient or a donor, has been practiced for decades, is well understood, and offers reliable results.
Reconstruction uses either hamstring tendons or a part of the patella tendon as graft material. This is fixed in place at the origin and insertion of the patient’s ACL. The procedure requires the removal of any remaining ACL tissue and the points of fixation of the graft material do not exactly match the pattern of attachment that the native ACL enjoyed.
Advantages:
- A long history (over 40 years) of results giving a measure of outcome certainty.
- Other knee injuries, such as meniscal tears, can be addressed simultaneously.
Disadvantages:
- An invasive procedure.
- Expensive in the private health system, or 12-month waiting list in the public health system.
- 15%-30% re-rupture rate, depending on age / sport.
- Requires a long period of rehabilitation. Return to sport is not recommended before 12 months.
2. NON-SURGICAL REHABILITATION
An alternative treatment option to ACL reconstruction surgery is management with exercise-based rehabilitation. Non-surgical rehabilitation is widely practiced, especially in northern Europe, where the public health authorities, after extensive research, deem this is the preferred initial management of acute ACL injury. This is also practiced by default in the UK where the wait time for any reconstructive surgery is at least one year. Patients adopt this treatment and patients who suffer recurrent knee instability and/or significant symptoms (pain, swelling, loss of function) “cross-over” to delayed ACL reconstructive surgery.
A 2014 prospective cohort study found there were essentially no differences in outcomes following non-surgical and surgical treatment of ACL injury. This included knee function, strength, time, sports participation, level of sport, and re-injury rate at 2-year followup (ref). A 2022 meta-analysis concluded that primary rehabilitation with optional surgical reconstruction results in similar patient-reported outcomes for ACL rupture as early surgical reconstruction (ref).
Rehabilitation aims to strengthen the surrounding muscles to provide dynamic stability to the knee, to replace the static stability of the ACL. Recent research is showing that in some of these patients the ACL actually heels without surgery. 2022 research suggests that about one-third of ruptured ACLs display evidence of healing on MRI when patients are managed with rehabilitation only, and that ACL healing is associated with favourable outcomes compared with early or delayed ACLR (ref). Approximately half (53%) of all participants randomised to rehabilitation who did not cross over to delayed ACL reconstruction (ACLR) had evidence of ACL healing on MRI at 2-year and 5-year follow-up.
Advantages:
Disadvantages:
An alternative treatment option to ACL reconstruction surgery is management with exercise-based rehabilitation. Non-surgical rehabilitation is widely practiced, especially in northern Europe, where the public health authorities, after extensive research, deem this is the preferred initial management of acute ACL injury. This is also practiced by default in the UK where the wait time for any reconstructive surgery is at least one year. Patients adopt this treatment and patients who suffer recurrent knee instability and/or significant symptoms (pain, swelling, loss of function) “cross-over” to delayed ACL reconstructive surgery.
A 2014 prospective cohort study found there were essentially no differences in outcomes following non-surgical and surgical treatment of ACL injury. This included knee function, strength, time, sports participation, level of sport, and re-injury rate at 2-year followup (ref). A 2022 meta-analysis concluded that primary rehabilitation with optional surgical reconstruction results in similar patient-reported outcomes for ACL rupture as early surgical reconstruction (ref).
Rehabilitation aims to strengthen the surrounding muscles to provide dynamic stability to the knee, to replace the static stability of the ACL. Recent research is showing that in some of these patients the ACL actually heels without surgery. 2022 research suggests that about one-third of ruptured ACLs display evidence of healing on MRI when patients are managed with rehabilitation only, and that ACL healing is associated with favourable outcomes compared with early or delayed ACLR (ref). Approximately half (53%) of all participants randomised to rehabilitation who did not cross over to delayed ACL reconstruction (ACLR) had evidence of ACL healing on MRI at 2-year and 5-year follow-up.
Advantages:
- Non-invasive
- A degree of efficacy found in clinical trials
- Less expensive
- Return to sport between 3 and 6 months depending on damage to other structures in the knee
- Surgery is still an option for those who do not get a good result.
Disadvantages:
- Potentially an ACL deficient knee
- Concern regarding not doing "everything" possible.
3. ACL CROSS BRACING PROTOCOL (CBP)
The Cross Bracing Protocol (CBP) is a form of non-surgicalrehabilitation where the chance for the ACL to heal in a functional fashion is facilitated and enhanced.
This outcome is achieved through careful selection of the type of injury to the ACL, and through the bracing protocol which puts the injured ACL in a position to heal naturally and protects it while this healing is happening. In effect this is an extension of Rehabilitation alone, an extension which can be offered to about half of all acutely injured ACL patients. The half of patients that have an injured ACL who are unlikely to benefit from the CBP can be offered surgery in the first instance or to consider adopting “rehabilitation alone”.
Advantages:
Disadvantages:
More information on the ACL Cross Bracing Protocol is here.
The Cross Bracing Protocol (CBP) is a form of non-surgicalrehabilitation where the chance for the ACL to heal in a functional fashion is facilitated and enhanced.
This outcome is achieved through careful selection of the type of injury to the ACL, and through the bracing protocol which puts the injured ACL in a position to heal naturally and protects it while this healing is happening. In effect this is an extension of Rehabilitation alone, an extension which can be offered to about half of all acutely injured ACL patients. The half of patients that have an injured ACL who are unlikely to benefit from the CBP can be offered surgery in the first instance or to consider adopting “rehabilitation alone”.
Advantages:
- An anatomically healed ACL is hypothesised to be as strong as the patient’s original ACL tissue.
- Non-invasive
- A degree of efficacy found in clinical trials
- Less expensive
- Surgery still an option for those who do not get a good result.
Disadvantages:
- Long period committed to the process
- The need to wear a knee brace for twelve weeks. This is both challenging and inconvenient. The analogy that a ruptured ACL is equivalent to a fractured tibia that will heal without surgery, but there is a need for immobilisation (a plaster cast for the fractured tibia) and crutches.
- Requires a long period of rehabilitation
- Return to sport is not recommended before 12 months.
More information on the ACL Cross Bracing Protocol is here.
