Why are Female Athletes Prone to ACL Injuries?

Compared to male athletes, female athletes are more prone to anterior cruciate ligament (ACL) injuries. Studies show that women are 3-8 times more likely to sustain an ACL injury compared to men. The question is why? Considerations include a smaller diameter ACL, a more narrow bony notch in the femur in which the ACL sits, the fact that women tend to be more knock kneed in their alignment, altered landing mechanisms, and possibly hormonal effects on ligament laxity and strength.

Biomechanical studies analyzing female versus male performance with similar tasks has shown that female athletes tend to subject their ACL to higher stresses. These same biomechanical differences are also likely increasing their injury rate.

The biomechanical differences affecting a female athlete’s knee are:

A more knock kneed (valgus) alignment
A tendency to land from a jump with the knee in a valgus position
Decelerating with the center of gravity posterior and the knee more extended or more straight.
Differences in quadriceps, hamstring, and gluteal strength such that the quad dominates. The gluteal musculature is weaker contributing to the valgus position of the knee. Weakness and tightness of the hamstrings places higher stresses on the ACL.

It is the combination of anatomy, biomechanics, and movement related to athletics that contributes to the higher rate of ACL injuries in female athletes.

Do Female Athletes Need ACL Surgery?

Older female athletes who have sustained an ACL tear can often be treated without surgery. Nonsurgical treatment consists of physical therapy to address muscle imbalances, knee bracing, and resuming low impact activities initially. In addition, a sports medicine professional can work with the patient to recommend technique modification, movement improvement, and collateral strength development to address the biomechanics.

Younger female athletes who wish to resume high level cutting and pivoting sports often require surgery. Following an ACL tear, there is initially significant pain, swelling, and instability but with time, the knee pain and swelling usually resolves and the knee can feel nearly normal. However, if one were to then resume cutting and pivoting sports following an ACL tear, the knee will most likely give way, causing pain, swelling, and possibly further damage to the cartilage in the knee.

For the female athlete contemplating ACL surgery, there are several considerations:

Athlete’s age
Current sports
Desire to return to same activity level
Type of job and demand on the knee joint
Type of hobbies such as hiking, dancing, etc.
Post-surgery functional expectations

These considerations along with a comprehensive orthopedic physical examination and imaging, to include xrays and an MRI, will help the female athlete decide if there is a need for ACL surgery.

What is the Best ACL Graft for Female Athletes?

The first choice when deciding on an ACL graft is choosing between an allograft (tendon from a donor) or autograft (tendon from the patient). Dr. Cunningham and other sports medicine surgeons that do a high volume of ACL surgery recommend autograft and not allograft. Studies have repeatedly demonstrated a higher retear rate with allografts, particularly in younger patients.

Autograft options for ACL reconstruction are utilizing the:

Central one third of the patellar tendon
2 of the medial hamstring tendons
Central one third of the quadriceps tendon

Patellar tendon and hamstring tendon autografts have been utilized for several decades with very good results. Use of a quadriceps tendon autograft has been widely used for nearly 10 years and the results have been excellent.

Some concerns with the use of a patellar tendon autograft for ACL reconstruction:

Higher incidence of permanent pain with kneeling following surgery
Higher incidence of pain in the front of the knee
Higher incidence of developing knee arthritis earlier in life in some studies
Although rare, a higher risk of a subsequent patella fracture

Some concerns with the use of a hamstring tendon autograft for ACL reconstruction:

The tendon graft being smaller than the native ACL, especially in females of smaller stature
The graft gradually stretching out over time causing recurrent knee instability
Decreased hamstring strength

Given this, a quad tendon autograft is a great option for female athletes requiring ACL reconstruction surgery. ACL doctor Richard Cunningham, MD utilizes the quad tendon for most of his female ACL reconstruction patients.

What are the Benefits of a Quad Tendon for Female Athletes?

Excellent outcomes have been demonstrated with the use of the quadriceps tendon for female athletes requiring ACL reconstruction. The quad tendon is also frequently used for ACL reconstruction revision surgery in female athletes who have torn their ACL graft and need their surgery redone.

The benefits of a quad tendon graft for female athletes include:

Unlike a patellar tendon autograft, no need to harvest sections of the bone from the patella and tibia along with the patellar tendon
88% thicker tendon graft compared to a patellar tendon graft.
The quad tendon is long and can accommodate various graft lengths
Minimally invasive incisions to the harvest site
Easier harvesting process
Reduced incidence of anterior knee pain compared to a patellar tendon graft

What is Recovery Like After ACL Surgery in Female Athletes?

Patients go home the same day as surgery. They are in a knee brace and on crutches for several weeks. Patients can bear weight on the knee immediately after surgery, but it may take 2-3 weeks to be able to walk without crutches and to discontinue the knee brace. Physical therapy is started the day after surgery with patients then going 2-3 times per week for several months. The first goal is to decrease swelling and restore knee range of motion. Patients can spin on a stationary bike as soon as they can get around on the pedals. Walking is limited to in home walking for the first 2 weeks to minimize swelling and maximize knee range of motion.

By 8 weeks from surgery, patients can be riding a bike outdoors on flat roads. By 12 weeks, patients can do light hiking. By 16 weeks, patients can start to jog. It can take 8 months to be able to return to cutting and pivoting sports such as soccer or skiing.

During your rehabilitation, your physical therapist will work on normalizing any muscle imbalances and working on restoring normal biomechanics, which will help prevent reinjury to the knee or injury to your other knee. The female athlete will be able to return to full activity with good strength, improved biomechanics and the confidence that the recovery program has been accomplished to the best possible outcome.