Treatment Methods for Anterior Cruciate Ligament (ACL) Injury

Yuan Yi

Capital Medical University, Beijing, China

Keywords: Anterior Cruciate Ligament (ACL) Injury, Rehabilitation, Biological Augmentation.

Abstract: Anterior cruciate ligament (ACL) injury is a common sports-related injury in clinical practice that severely

affects the patient's mobility and quality of life. Treatment methods for ACL injury include conservative

treatment and surgical treatment, among which arthroscopic ACL reconstruction is the most widely used

surgical approach. Rehabilitation plays a crucial role in the treatment process, and a scientifically designed

rehabilitation plan can not only promote postoperative recovery but also reduce the risk of secondary injury.

This article reviews the epidemiological background, diagnostic methods, treatment plans, and rehabilitation

strategies for ACL injuries, analyzes the advantages and shortcomings of existing treatment methods, and

discusses possible future optimization directions.

1 INTRODUCTION

ACL injuries can generally be categorized into partial

tears and complete ruptures. In partial tears, the

ligament fibers are not completely torn, and some

stability is retained, though it may lead to limited

knee movement or pain. In complete ruptures, the

ACL is fully torn, causing a significant decrease in

knee stability. Patients may experience joint laxity,

functional impairment, and an increased risk of

secondary injury. After an ACL injury, the stability,

coordination, and balance of the knee joint are all

affected, and it may also be accompanied by damage

to the meniscus, collateral ligaments, and cartilage,

further exacerbating knee dysfunction (Sun, 2024).

The incidence of ACL injuries is influenced by

factors such as age, gender, and type of sport.

Statistics show that approximately 30 to 80 cases of

ACL injuries occur annually per 100,000 people,

with a particularly high incidence in competitive

sports. Female athletes are at a 2 to 8 times higher risk

of ACL injury compared to males, which may be

related to anatomical structure, biomechanics, and

hormonal factors. Globally, the incidence of ACL

injuries is rising. For example, in the United States,

approximately 250,000 people sustain an ACL

rupture due to sports each year, and the majority of

these patients require ACL reconstruction (ACLR).

ACL injuries not only affect professional athletes but

are also common among adolescents and recreational

sports enthusiasts, potentially leading to long-term

impacts on their athletic abilities, daily life, and

mental health (Pan, 2024 & Xu, 2024).

The causes of ACL injuries can be divided into

non-contact and contact injuries. Non-contact

injuries, which account for over 70% of cases,

typically occur during activities such as landing from

a jump, sudden stops, or quick changes in direction.

These injuries result from knee valgus, excessive

anterior tibial translation, or rotational forces, which

overload the ligament. Non-contact ACL injuries are

common in sports such as basketball, soccer, and

volleyball. Contact injuries are more prevalent in

sports like football and rugby, where direct external

force is applied to the knee joint, potentially leading

to ACL tears or ruptures.

2 DIAGNOSIS

Accurate diagnosis of anterior cruciate ligament

(ACL) injury is crucial for developing an appropriate

treatment plan. Clinically, ACL injury is primarily

assessed through MRI, X-ray, and physical

examination.

MRI (Magnetic Resonance Imaging) is a high-

resolution imaging technique that can clearly display

the morphology, position, and integrity of the ACL

and is widely used in the clinical diagnosis of ACL

injuries. Currently, the MRI diagnosis of ACL

injuries relies on both direct and indirect signs. Direct

signs refer to abnormal changes in the ACL's signal

or morphology, including discontinuity (signal

interruption, typically seen in fresh injuries),

444

Yi, Y.

Treatment Methods for Anterior Cruciate Ligament (ACL) Injury.

DOI: 10.5220/0014495000004933

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

In Proceedings of the 1st Inter national Conference on Biomedical Engineering and Food Science (BEFS 2025), pages 444-447

ISBN: 978-989-758-789-4

abnormal direction (the ACL appears abnormally

angled or drooping), signal loss (no ACL signal in the

intercondylar notch, often seen in chronic injuries),

and pseudo-tumor formation (proliferation of tissue

at the torn ends, encapsulated by synovium). Indirect

signs include meniscal damage (with 22.50% of cases

involving lateral meniscus damage and 20.00%

involving medial meniscus damage), collateral

ligament injuries (20.00% medial and 2.50% lateral),

bone contusions (62.50%), and Segond fractures

(12.50%), which occur on the lateral tibial plateau

and suggest a higher likelihood of ACL injury. MRI

offers a high diagnostic accuracy rate (95.34%), is

non-invasive, and provides multi-planar imaging,

making it the gold standard for diagnosing ACL

injuries. However, it is relatively costly, time-

consuming, and may have some limitations in early

assessment of acute injuries (Pan, 2024).

X-ray examination is primarily used to exclude

fractures and can also be used to observe bone

contusions or skeletal abnormalities. For example, a

Segond fracture (avulsion fracture on the lateral tibial

plateau) may indicate the presence of ACL injury.

Although X-ray cannot directly show the ACL itself,

it still holds value in the auxiliary diagnosis of ACL

injuries.

Physical examination, combined with the patient's

medical history, can serve as an initial screening

method for ACL injury. Common examination

techniques include the Lachman Test, the Anterior

Drawer Test, and the Pivot-Shift Test. In the

Lachman Test, when the ACL is injured, the tibia

moves anteriorly to a greater extent, indicating a

positive result. The Anterior Drawer Test evaluates

the degree of anterior tibial translation to assess the

integrity of the ACL. The Pivot-Shift Test is the most

specific physical examination for ACL injury but

requires the patient to relax their muscles, making it

difficult to perform during the acute injury phase.

3 TREATMENT

Recent advancements in the treatment of ACL

injuries focus on improving the healing process

through biological augmentation (BA) techniques,

which aim to enhance graft healing and improve

long-term outcomes post-surgery. One of the most

studied BA methods is platelet-rich plasma (PRP),

which is believed to promote graft healing by

providing growth factors that aid tissue regeneration

and remodeling. Studies have shown mixed results,

with some indicating that PRP can accelerate the graft

maturation process and improve knee function, while

others report minimal or no clinical benefits (Shen,

Shi & Li, 2024).

Biological augmentation can be applied during

ACL reconstruction (ACLR) through techniques

such as the use of PRP, mesenchymal stem cells

(MSCs), or various growth factors like bone

morphogenetic proteins (BMPs). These techniques

aim to optimize graft healing, enhance

osseointegration at the graft-tunnel interface, and

promote better ligamentization of the graft. However,

the clinical evidence supporting the routine use of BA

in ACLR remains inconclusive. A survey indicated

that a minority of surgeons currently use BA in

primary ACLR, and those who do report inconsistent

clinical outcomes (L, 2025).

Studies on animal models have shown that BA

techniques, including PRP and stem cell applications,

can significantly improve graft healing by enhancing

vascularization and graft-to-bone integration. Despite

promising animal study results, the application of

these techniques in clinical practice is still debated

due to variability in outcomes and a lack of robust

evidence from randomized controlled trials. The use

of PRP has been particularly controversial, with some

studies suggesting it accelerates healing, while others

fail to demonstrate substantial clinical improvements.

The timing of ACL surgery remains a critical

factor in treatment outcomes. Research suggests that

early reconstruction, typically within 1 to 2 weeks

after injury, leads to quicker recovery and lower

complication rates. Delayed surgery, however, might

impair long-term knee function, prolonging

rehabilitation. Preoperative rehabilitation focusing on

strength training, neuromuscular coordination, and

joint mobility is also shown to positively impact

postoperative recovery, leading to improved muscle

function and reduced postoperative pain (Failla,

Arundale, Logerstedt & Snyder-Mackler, 2015).

Post-ACLR rehabilitation remains a key

component of treatment success. It is crucial for

restoring knee function, improving quadriceps

strength, and ensuring the return of full range of

motion. Emphasizing neuromuscular training during

rehabilitation can also reduce the risk of reinjury and

improve knee stability. Furthermore, psychological

factors such as fear of reinjury or returning to sports

play a significant role in recovery. Incorporating

psychological support into rehabilitation programs

can help address these concerns, facilitating a

smoother return to physical activity (Xu, Yang,

Zhang, et al. 2025 & Rodríguez-Merchán, 2021).

Treatment Methods for Anterior Cruciate Ligament (ACL) Injury

445

4 ACL REHABILITATION

Rehabilitation after ACL surgery is crucial for

restoring knee function. A well-designed

rehabilitation plan not only helps maximize the

surgical outcomes but also reduces the risk of

secondary injuries and improves the patient's athletic

performance. In recent years, research on post-ACL

reconstruction rehabilitation has advanced

significantly, showing that optimizing rehabilitation

plans is key to successful recovery (Jin, & Li, 2024).

Post-ACL surgery, rehabilitation now focuses not

just on restoring knee joint function but also on

optimizing movement patterns and improving

neuromuscular control. Studies have shown that fast-

track rehabilitation programs can speed up knee

function recovery compared to traditional methods,

particularly for athletes. A properly structured plan

can help them return to sports more quickly.

Additionally, neuromuscular training plays a central

role in rehabilitation. By using strength training,

balance exercises, and plyometric training, this

approach can effectively correct lower limb

biomechanical imbalances, enhance dynamic knee

stability, and reduce the risk of reinjury. This type of

training not only improves muscle control but also

optimizes an athlete’s movement patterns, helping

them maintain high levels of athletic performance

during recovery (Xu, Jiang, Zong, et al. 2024).

For muscle strength recovery after surgery,

isokinetic strength training is widely used in ACL

rehabilitation. Research shows that isokinetic training

allows for precise measurement of muscle strength

around the knee, aiding in the development and

adjustment of rehabilitation plans. By using both

concentric and eccentric training modes, isokinetic

training improves the coordination between the

quadriceps and hamstrings, stabilizing the knee joint

and promoting post-surgery athletic recovery. In the

early stages of rehabilitation, combining

neuromuscular electrical stimulation and

proprioceptive training helps to strengthen the knee’s

neuromuscular control and improve dynamic

balance, reducing the risk of asymmetrical movement

patterns during recovery (Xu, Jiang, Zong, et al. 2024

& Jin, Li, 2024).

The rehabilitation plan after ACL surgery should

be tailored to the individual. In the early stages, the

focus should be on inflammation control, restoring

joint range of motion, and proprioceptive training. As

recovery progresses, strength training,

neuromuscular exercises, and isokinetic training

should be gradually introduced to improve knee

stability and function. For athletes, fast-track

rehabilitation helps them return to their competitive

level more quickly, while non-athletic patients can

follow a more gradual plan to ensure long-term knee

health and stability. With a well-structured

rehabilitation strategy, recovery time can be

shortened, the risk of secondary ACL injuries

reduced, and overall athletic performance

significantly improved (Qin, Qian, 2017 & Kong, Li,

2019).

5 CONCLUSION

The treatment methods for ACL injuries are

constantly evolving and improving. Significant

progress has been made in both precision and

recovery efficiency. Surgical treatments, especially

arthroscopic ACL reconstruction, have become the

preferred option for most patients due to its

minimally invasive nature, high postoperative

stability, and controlled rehabilitation process.

However, conservative treatment still holds value for

individuals with low activity levels, particularly

when surgery might pose potential risks. Despite

these advantages, both approaches have their

drawbacks. While surgery can restore knee stability,

there is still a risk of recurrence and a lengthy

recovery period. Conservative treatment, although

less invasive, struggles to fully restore knee function,

particularly for individuals with high physical

activity demands, and its long-term effectiveness

may be limited.

To overcome these limitations, personalized

treatment plans and optimized rehabilitation

strategies are crucial. The focus of postoperative

rehabilitation should not only be on restoring joint

range of motion and muscle strength but also on

enhancing neuromuscular control to reduce the risk

of secondary injuries due to abnormal movement

patterns. Isokinetic and neuromuscular training have

proven to be highly effective in ACL recovery, and

future advancements could include integrating new

technologies like virtual reality training and robot-

assisted rehabilitation to further improve precision

and efficiency. Additionally, prevention should not

be overlooked. Improving athletes’ body control,

optimizing movement patterns, and promoting

preventive training programs for high-risk sports

could play a more significant role in reducing the

incidence of ACL injuries.

While current treatments can help most patients

return to daily activities and even sports, there is still

room for improvement. Future research should not

only focus on postoperative recovery but also delve

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deeper into strategies for preventing ACL injuries,

ultimately reducing the risk of sports-related injuries

for patients.

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