The anterior cruciate ligaments(ACL) are intra-articular, extra-synovial and multi-fascicular structures made up of 2 bundles that originate from the medial aspect of posterior intercondylar area of lateral femoral condyle and insert between the anterior horns of the medial and lateral menisci.
They play significant roles in a stability of the knee joint, which are primary static structures resisting anterior translation of tibia on femur and secondary resistor on tibial rotation.
In a real life, an average load on ACL while walking is about 400-500N and it increases up to 1700N with sudden acceleration or deceleration. 
As a spare time activity is of great importance, there are increasing number of people playing sports, being injured through the activities or accidents.
In United States, over 1000 thousands of people get a ACL reconstruction surgery annually.
By far the most common mechanism of the ACL injury is abduction, flexion, and internal rotation of the femur on the tibia when the weight-bearing leg of a person is struck from the lateral aspect by an opponent. Sports where the ACL injury commonly occurs are soccer, basketball, skiing, etc.
Acute phase treatment is focused on several aspects; minimizing hemarthrosis, recovering range of motion, the function of quadriceps muscle, proprioception and walking ability. In active patients non-surgical treatment can not get a satisfactory result.
In a surgical treatment, a reconstruction of ACL is recommended as a standard therapy as other procedures including a repair or augmentation methods do not have surgical reproducibility and long-time stability.
The strength of the graft is strongest right after the surgery and a necrosis progresses for 6 weeks at which the graft strength is weakest. A migration and proliferation of cells occur at 8 weeks to 10 weeks after the surgery and for several months they attach to bone slowly, forming a shape of the ACL ligament grossly. Therefore an early immoderate rehabilitation protocol may result in an unstable graft maturation and instability of the knee joint. In general, range of motion(ROM) exercise is recommended to be started after 1 week of a reconstruction surgery. However, recent several studies on animal testing show that a late ROM exercise aids graft healing. Furthermore, some reports insist that there is no difference on the outcome of the surgery in regard of the time to start ROM exercise. So, there is no consensus on the postoperative rehabilitation protocol especially on an accurate time for the initiation of ROM exercise.
In this study, it is designed to compare the results of the treatment between early rehabilitation group in which patients get ROM exercise within 3 days after the ACL reconstruction surgery and delayed rehabilitation group in which patients get ROM exercise after 3 weeks of the surgery when some collagen fibers including indirect Sharpey’s fiber are formed on grafts.

Treatment

The patients who underwent an anterior cruciate ligament reconstruction surgery were divided into two groups; early group that initiates a continuous passive range of motion exercise in 3 days after the surgery and delayed group that initiates the rehabilitation after 3 weeks of the surgery.
 Through the early exercise, the patients in the early group can return to everyday life and sports earlier than patients in the other group. However, a verification on functional and radiologic stability of the reconstructed anterior cruciate ligament is required through this study. Every variable other than the time when to start continuous range of motion exercise is identical to the other group.

Arm Label

Target Number of Participant

Arm Type

Arm Description

A group undergoes delayed continuous passive range of motion exercise 3 weeks after the anterior cruciate ligament reconstruction surgery. Through the exercise, the patients in the group are expected to get more stability of the reconstructed anterior cruciate ligament. However, the three weeks of immobilization of the injured knee and a concomitant stiffness can delay the time to return to everyday life and sports. Every variable other than the time when to start continuous range of motion exercise is identical to the other group.

Arm Label

Target Number of Participant

Arm Type

Arm Description

A group undergoes early continuous passive range of motion exercise in 3 days after the anterior cruciate ligament reconstruction surgery. Through the exercise, the patients in the group can return to everyday life and sports earlier than the other group. However, a verification on functional and radiologic stability of the reconstructed anterior cruciate ligament is required through this study. Every variable other than the time when to start continuous range of motion exercise is identical to the other group.

Gender

Age

Description

Patient who gives written consent after full explanation of the study.
Man or woman who is over 18 years old
Patient who shows positive results on pivot shift test and anterior drawal test
Patient who shows anterior cruciate ligament rupture on knee joint MRI
Patient who has acute isolated ACL injury 
Patient who shows knee joint range of motion as good as 90% of pre-injury range of motion

Patient who is under than 18 years old
Patient who has additional injury other than anterior cruciate ligament injury such as posterior cruciate ligament, lateral collateral ligament, medial collateral ligament, etc.
Patient who underwent meniscus repair surgery
Patient who has past history of a fracture or a surgery on the injured knee joint
Patient who is not proper for the study from a view of the lead researcher
Patient who has an active infection on the injured knee joint

Reconstructed tunnel sizes of the femur and tibia

Post operative day of 3 weeks, 6 weeks, 3 months, 6months, 12months, 24months

Arthrometer exam(KT-2000)

Post operative day of 3 weeks, 6 weeks, 3 months, 6months, 12months, 24months

Degree of the reconstructed anterior cruciate ligament graft synovialization measured through knee MRI

Post operative day of 1 year

Range of motion,  Muscle strength, Muscle circumference

Post operative day of 3 weeks, 6 weeks, 3 months, 6months, 12months, 24months

Anterior draw test grade, Pivot shift test grade

Post operative day of 3 months, 6months, 12months, 24months

Visual analogue scales, International knee documentation committee score, Lysholm score , Tegner score

Post operative day of 3 weeks, 3 months, 6months, 12months, 24months

Single hop test, Vertical hop test, Y-balance test 

Post operative day of 3 months, 6months, 12months, 24months