Overview of Treatment Methods for Anterior Cruciate Ligament

(ACL) Injuries in the Knee Joint

Jialin Xu

School of Nursing, Inner Mongolia MinZu University, TongLiao, Mongolia, China

Keywords: Anterior cruciate ligament (ACL) injury, Surgical reconstruction, Rehabilitation

Abstract: Anterior cruciate ligament (ACL) injuries are a significant clinical issue affecting joint function. This

article systematically reviews the epidemiological background, diagnostic methods, treatment strategies,

and rehabilitation approaches for ACL injuries. Epidemiological analysis shows that 70% of ACL injuries

result from non-contact injuries in sports, primarily manifesting as sudden swelling, pain, and joint

instability in the knee, along with secondary meniscal injuries. Diagnosis mainly relies on MRI (accuracy

> 90%) combined with X-rays. Treatment strategies are divided into surgical reconstruction and

conservative treatment. Surgical reconstruction is suitable for young, active patients and professional

athletes, as it can effectively restore knee joint stability and prevent secondary meniscal injuries, but it

carries risks of limited range of motion and complications such as infection. Conservative treatment is

suitable for patients with low-intensity activities, but long-term follow-up shows that 40% require later

reconstruction. Treatment decisions need to comprehensively Adjust training through a phased

rehabilitation plan.

1 EPIDEMIOLOGICAL

BACKGROUND OF ACL

The anterior cruciate ligament (ACL), as a core

structure maintaining the dynamic stability of the

knee joint, often leads to joint biomechanical

disorders, loss of motor function, and increased risk

of secondary osteoarthritis when injured. With the

popularization of sports and the increase in traffic

injuries, the incidence of ACL injuries has been rising

year by year, becoming a key issue in the fields of

orthopedics and sports medicine.

The knee joint is the most complex hinge joint in

the human body, and its stability relies on the

coordinated regulation of the anterior and posterior

cruciate ligaments. Among them, the anterior cruciate

ligament (ACL) serves as a key stabilizing structure,

originating from the anterior intercondylar area of the

tibia, connecting the femur and tibia, and inserting

into the medial aspect of the lateral condyle of the

femur. It extends obliquely upward and outward with

an average length of 31-38mm and an average width

of 10-12mm, it extends diagonally outward and

upward, forming an oval cross-section (Ao et al,

2001). Its unique anatomical orientationprovides

relative stability to the joint, preventing the tibia from

moving forward relative to the femur, and it is also

the structure most susceptible to injury during knee

joint damage.

The mechanisms of ACL injury present two

patterns: high-energy trauma (such as traffic

accidents) accounts for about 27%, for example, ACL

injuries caused by rapid twisting movements of the

knee joint due to uneven ground. Low-energy non-

contact injuries (such as in sports) dominate,

accounting for about 70% (Ao et al, 2001; Waldén et

al, 2022; Della Villa et al, 2020). These are also

known as sports injuries and often occur in basketball

and football during sudden deceleration, changes in

direction, rotation, or jumping.

According to the progression of the condition,

ACL injuries can be divided into three stages: the

acute phase (less than 3 weeks), where patients often

experience sudden joint swelling, severe pain, and

restricted movement; the subacute phase (3 weeks to

3 months), where pain subsides but joint instability

remains; and the chronic phase (more than 3 months),

which is characterized by recurrent joint effusion,

typically manifesting as the "giving way"

phenomenon during movement and secondary

meniscus injuries.

According to the progression of the condition,

ACL injuries can be divided into three stages: the

acute phase (less than 3 weeks), where patients often

experience sudden joint swelling, severe pain, and

Xu, J.

Overview of Treatment Methods for Anterior Cruciate Ligament (ACL) Injuries in the Knee Joint.

DOI: 10.5220/0014487700004933

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 1st International Conference on Biomedical Engineering and Food Science (BEFS 2025), pages 319-323

ISBN: 978-989-758-789-4

319

restricted movement; the subacute phase (3 weeks to

3 months), where pain subsides but joint instability

remains; and the chronic phase (more than 3 months),

which is characterized by recurrent joint effusion,

typically manifesting as the "giving way"

phenomenon during movement and secondary

meniscus injuries.

2 ACL DIAGNOSIS

According to arthroscopy, ACL injuries can be

classified into four grades. A normal ACL has a

normal shape, represented by 0 degrees. Grade 1: The

ACL shape is basically normal, with ligament

damage; Grade 2: The ACL is slightly lax, with

partial tearing; Grade 3: The ACL is lax, with most of

the ligament torn; Grade 4: The normal shape

disappears, the ligament is extremely lax, and the

ligament is completely torn.

ACL (anterior cruciate ligament) injuries are

usually first assessed through small tests such as

stress tests, drawer tests, and pivot shift tests, but are

generally confirmed through MRI (magnetic

resonance imaging) and X-rays. The most commonly

used diagnostic method is MRI diagnosis rate exceeds

90%, which utilizes nuclear magnetic resonance for

comprehensive scanning. A torn anterior cruciate

ligament will show specific signals, much like seeing

a red flag (Liao, 2020). In addition, MRI can also

assess whether there are any associated meniscus,

cartilage, or other ligament injuries in the knee joint.

Another advantage is that it does not involve any

radiation, although sometimes MRI may miss parts of

the ligaments, leading to missed diagnoses (Ao et al,

2022). X-rays are mainly used to rule out associated

fractures, such as Segond fractures, which are very

common, especially in small hospitals. This is

because they are inexpensive and very suitable for

observing bones. However, due to their radiation

risks, they may cause adverse reactions in patients

(Shea and Carey, 2015; Wang and Sun, 2023).

Clinically, doctors usually combine MRI and X-ray

results with the patient's clinical symptoms and signs

to comprehensively assess the condition of ACL

injuries and formulate the most appropriate treatment

plan. In summary, MRI and X-ray examinations play

an important role in the diagnosis of ACL injuries, but

they still need to be combined with clinical

manifestations for a comprehensive evaluation.

3 ACL TREATMENT

The treatment strategies for anterior cruciate ligament

(ACL) tears in the knee joint are mainly divided into

two categories: surgical reconstruction and

conservative treatment. Surgical reconstruction,

centered on minimally invasive techniques, restores

the biomechanical stability of the knee joint through

arthroscopically assisted ligament grafting, especially

suitable for young, active patients with high athletic

demands and secondary meniscus injuries. Non-

surgical treatment is based on physical therapy

protocols and is mainly suitable for individuals with

incomplete tears, low activity demands, or those with

surgical contraindications. Whether it is ACL

reconstruction surgery or conservative treatment, the

core of both therapies focuses on restoring joint

functional stability, preventing post-traumatic

osteoarthritis (OA), alleviating pain, and improving

the patient's long-term quality of life (John et al,

2025).

3.1 Surgical Treatment

3.1.1 Surgical Method

The most common arthroscopic surgeries are anterior

cruciate ligament (ACL) reconstruction and meniscus

tear repair. There are two menisci inside the knee,

which help protect the articular cartilage and allow

the bones to glide smoothly over each other during

movement. They also act as shock absorbers,

distributing the load across the knee. Therefore, it is

very common for the ACL and meniscus to be injured

simultaneously, especially among athletes. Of course,

elderly patients can also experience meniscus tears.

Research shows that over 60% of patients with ACL

tears also have meniscus tears. Depending on the

sport, the likelihood of ACL tears in women is 2 to 6

times that in men (Toth et al, 2001). When the ACL

is completely torn, surgeons must replace it with a

graft. The graft can be obtained from the patient's own

knee or from donated tissue. Generally speaking,

autografts are used for adolescents and young

athletes, while allografts are used for older patients

(Paschos et al., 2018).

The core goal of ACL injury reconstruction

treatment is to restore knee joint stability and

function. The main surgical indications include: 1)

young and middle-aged patients with knee joint

dysfunction, 2) significant knee joint instability or

abnormal internal and external rotation, and 3) cases

with obvious anatomical displacement. In terms of

reconstruction method selection, both single-bundle

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and double-bundle reconstructions are clinically

effective options. Studies have shown that there is no

significant difference between the two techniques in

restoring knee joint stability. However, it is

noteworthy that the positive rate of the axial shift test

after double-bundle reconstruction is significantly

lower than that after single-bundle reconstruction

(Zhu et al, 2013; Xiang et al, 2019). Nevertheless,

clinical decisions should comprehensively consider

various factors such as the patient's age, occupational

characteristics, comorbidities, and activity demands.

3.1.2 Postoperative Complications

The spectrum of complications after ACL

reconstruction is similar to those of conventional knee

arthroscopy, mainly including limited joint mobility,

poor wound healing, joint cavity infection, and deep

vein thrombosis, among others (Sun et al, 2014). A

stratified prevention and control strategy should be

adopted for the aforementioned complications:

Regarding the limitation of knee joint mobility

after surgery, it is recommended to strictly control the

surgical indications before the operation, ensure

precise anatomical positioning during the operation,

implement early functional exercises after the

operation, and it is suggested that passive mobility

after 4 weeks and active mobility after 6 weeks should

reach ≥90° (Ekhtiari et al, 2017). In response to the

risks of poor incision healing and postoperative

infections, a comprehensive preoperative assessment

of the patient's skin condition and infection risk

indicators is required to choose the appropriate timing

for surgery. Additionally, strict adherence to aseptic

principles during the operation is essential, with

gentle handling and attention to protecting the soft

tissues around the incision. Postoperative close

monitoring of inflammatory indicators is essential.

When adverse reactions such as poor wound healing

and knee joint infections occur, early intervention

measures such as antibiotics and joint clean -ing

should be used for treatment. Postoperatively,

simultaneously strengthen the prevention of

thrombosis, and closely monitor the patient's

coagulation function and lower limb circulation status

throughout the perioperative period. For high-risk

patients, it is recommended to use mechanical

prevention, such as intermittent pneumatic

compression devices, in conjunction with a

comprehensive regimen of anticoagulant medication.

3.2 Non-Surgical Treatment

Conservative treatment for anterior cruciate ligament

(ACL) injuries requires first assessing the patient's

joint stability and its impact on motor function.

Typical manifestations of joint instability include

"giving way" of the legs while walking, and

limitations in rapid running and sudden stop actions.

If the patient can effectively avoid symptoms of joint

instability through adjustments in exercise intensity

or targeted functional training, conservative treatment

is indicated.

Conservative treatment can include the use of

topical traditional Chinese medicine, shortwave

therapy, massage, local blockade, wearing a brace for

2-3 months, and systematic rehabilitation training.

For example, chiropractic therapy requires a

combination of mechanical and manual operations to

diagnose and treat, and to enhance the body's natural

self-healing abilities. The benefits of chiropractic

therapy include: improving mobility and flexibility,

enhancing balance, and strengthening supporting

muscles. Chiropractors can also provide specific

rehabilitation exercises and physical therapy tailored

to individuals, focusing on the strength, flexibility,

and stability of the knees and surrounding muscles.

For cases of simple ACL partial tear or those not

causing acute joint instability, a long leg cast can be

used to fix the affected knee at a 30° flexion position

for 6 weeks. After 3 days of casting, isometric

contraction training of the quadriceps should begin to

prevent disuse muscle atrophy.

3.3 Compare

Regarding the progression of osteoarthritis and the

ability to return to sports after treatment, existing

studies indicate that there is no significant difference

in long-term prognosis between surgical and non-

surgical treatments (Chalmers et al, 2014). ACL

reconstruction itself cannot prevent the progression of

osteoarthritis; meniscus removal or meniscus injury

is the main cause of the progression of knee

osteoarthritis. But during the non-surgical treatment

of ACL injuries, many patients eventually experience

meniscus damage (Smith et al, 2014). Long-term

follow-up studies have shown that ACL

reconstruction can prevent meniscus injuries. In terms

of returning to sports, although there is no statistical

difference in the overall effectiveness of the two

treatment methods, clinical outcome analysis shows

that surgery has more advantages. Frobell et al.

(Frobell et al, 2010) conducted a controlled study that

showed no significant difference in functional

Overview of Treatment Methods for Anterior Cruciate Ligament (ACL) Injuries in the Knee Joint

321

recovery between the two groups after 2 and 5 years

of follow-up. However, 40% of the non-surgical

group required subsequent reconstruction, and 32%

needed a second surgery due to meniscus injuries. In

addition, the study by Bergerson et al. (Bergerson et

al, 2022) indicates that the surgical group showed

significantly better knee joint function scores,

symptom improvement, and quality of life at 1, 2, 5,

and 10 years of follow-up compared to the non-

surgical group. Although non-surgical treatment has

application value in specific cases, its use should be

approached with caution from the perspective of

preventing secondary injuries. For recurrent knee

instability, high-intensity sports demands, and

younger patients, ACL reconstruction remains the

recommended option.

4 ACL REHABILITATION

4.1 Postoperative Rehabilitation

Principles

Postoperative braces are not conventionally

necessary, but they can be used short-term (1-2

weeks) for patients with psychological needs; long-

term use may limit functional recovery. Theoret and

Lamontagne's (Théoret and Lamontagne, 2006) study

found that wearing a brace reduces the active range of

motion in the knee joint and increases hamstring

activity. Andersson et al. (Andersson, et al, 2009)

reported that the use of functional knee braces

postoperatively does not affect the prognosis of

patients after ACL reconstruction. If a functional knee

brace is to be prescribed after ACL reconstruction, a

cheaper knee sleeve or hinged knee brace would be

sufficient.

Neuromuscular training is being increasingly

applied in rehabilitation and sports-specific training

after anterior cruciate ligament reconstruction. At the

same time, people have also recognized that to

prevent sports-related knee injuries or re-injuries,

knee joint stability can be improved through

enhanced neuromuscular control (Hewett, et al,

1999). Risberg et al (Risberga, et al, 2004) designed

a neuromuscular training program for patients after

ACL reconstruction. In a 6-month follow-up, the

overall knee joint function scores in the

neuromuscular training group significantly improved

compared to the conventional strength training group.

But its effect is limited and should not replace

strength and range of motion training.

Keays et al. (Keays et al, 2006) compared 12

subjects with chronic unilateral ACL deficiency who

underwent a home exercise program with a control

group. They found that after 6 weeks of the program,

the exercise group showed significant improvements

in muscle strength, agility, and flexibility. They

recommended that all patients with ACL deficiency

should participate in preoperative physical therapy

before ACL reconstruction. Home rehabilitation is

effective for patients with high compliance and

requires the combination of visual and textual

guidance, regular remote feedback, and emergency

follow-up mechanisms. Its effectiveness is

comparable to outpatient supervised rehabilitation

(Saka, 2014; Risberga et al, 2004).

Enhancing confidence and rebuilding the "athlete

role" in research has found that after ACL

reconstruction, patients who engage in functional

exercises simulating sports movements early in

rehabilitation are more likely to return to sports.

Functional training is more likely to improve patients'

confidence and self-efficacy, and it helps them rebuild

the "athlete role" more quickly during their targeted

sports training. Additionally, shortening

postoperative care can improve patients' function and

reduce fear of movement (Brewer et al,1993;

Langford et al,2009; Nyland et al,2005).

4.2 Postoperative Recovery Phase and

Exercise Methods

Postoperative rehabilitation can be divided into six

progressive stages, and the exercise plan should be

scientifically arranged based on the postoperative

timeline: the first 0-2 weeks post-surgery should

focus on controlling acute inflammation, primarily

using ice packs, elevating the affected limb, and

performing ankle pump exercises. During weeks 3-5,

the focus shifts to restoring basic muscle strength and

joint mobility, with wall sits and glute bridges being

introduced; during weeks 6-8, the emphasis moves to

enhancing lower limb stability, with Bulgarian split

squats being added. Swimming (freestyle or water

jogging) can be resumed 8 weeks post-surgery.

During the 9-12 week transition period, start low-

intensity enhancement training, such as box jumps

and progressive skipping (transitioning from both

sides to one side); in the early 3-5 months of the

return-to-sport phase, focus on rebuilding endurance

and coordination by gradually adjusting intensity

through intermittent walking/jogging training (e.g.,

transitioning from 5 minutes of walking + 1 minute of

jogging to full jogging).After 6 months, enter the

unrestricted exercise period, where multidirectional

pivot jumps and non-contact competitive training are

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required, ultimately achieving full-intensity

specialized exercise adaptation (Kruse et al, 2012).

5 CONCLUSIONS

After an anterior cruciate ligament (ACL) injury,

doctors and patients should comprehensively

consider factors such as the extent of the injury and

the patient's age when choosing a treatment method

and jointly participating in a rehabilitation plan.

Regardless of the treatment strategy adopted, it

should address the injury, overcome psychological

barriers to movement, restore knee joint function,

minimize the occurrence of complications, and

optimize long-term quality of life. Although surgical

reconstruction remains the mainstream solution for

severe ACL injuries, However, non-surgical

rehabilitation has shown potential in some patients.

Although both approaches have their own advantages

and disadvantages, the author believes that post-ACL

injury treatment should strengthen patient care,

closely monitor the patient's temperature, breathing,

and other conditions, pay close attention to the skin

condition around the incision to prevent postoperative

complications, and adhere to sterile procedures when

changing medications. If unfortunately infected,

timely treatment should be administered to reduce

adverse reactions. At the same time, actively pay

attention to the patient's psychological state, listen to

their needs, and boost their confidence. In the future,

it is also necessary to combine precision medicine

with dynamic functional assessment to optimize

treatment methods and improve joint health levels. If

unfortunately infected, timely treatment should be

administered to reduce adverse reactions. At the same

time, actively pay attention to the patient's

psychological state, listen to their needs, and boost

their confidence. In the future, it is also necessary to

combine precision medicine with dynamic functional

assessment to optimize treatment methods and

improve joint health levels.

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