The following article has been reproduced by kind permission of the author, Tony Miller. The article is an abstract on a review of open and closed kinetic chain exercise following anterior cruciate ligament reconstruction which formed part of his submitted thesis for his masters degree.

Over the past ten years there has been a steady argument from physicians, therapists and coaches over which form of kinetic exercise is most beneficial following anterior cruciate ligament (ACL) reconstruction. Some of the therapists tend to agree that open kinetic chain exercise (OKCE) benefits the ACL the best. Some therapists believe that closed kinetic chain exercise (CKCE) are superior to OKCE. Recently, ACL ruptures have become the most common knee injury involved in the world of sports. There are approximately 250,000 ACL injuries in a given year. These injuries occur due to shear force placed on the ligament during any type of decelerating, turning, planting and cutting and different types landings. The ACL can with stand 400 pounds of pressure at any given time, therefore, injuries become more common in high impact sports. With injuries becoming more frequent, rehabilitation is becoming more important. The purpose of this review was to determine which form of kinetic chain exercise, open or closed, is most beneficial following ACL reconstruction. Following ACL reconstruction, the safest Kinetic Chain Exercise will decrease stress, strain and an increase in stability as well as range of motion.

During any exercise regiment, whether for rehabilitation purposes or for strengthening purposes, there are two types of Kinetic Chain Exercises used. The first is Open Kinetic Chain Exercises (OKCE). These exercises are performed typically were the foot is free to move. These exercises are typically non-weight bearing, with movement occurring at the knee joint. Examples of these exercises would be knee extensions and straight leg raises. OKCE concentrates on a strong quadriceps contraction, which will strengthen the quadriceps and restore quadriceps power output. The second exercise used is Closed Kinetic Chain Exercise (CKCE). CKCE are performed where the foot is fixed and cannot move. The foot remains in constant contact with the surface, usually the ground or the base of a machine. These exercises are typically weight bearing exercises, where an athlete or patient uses their own body weight and / or external weight. When external weight is added it is usually rested across the back of the shoulders or the front of the chest. Examples of these exercises would be the Squat (both front and back), Leg Press, Lunge, Power Clean and Snatch. These exercises are multi-joint movements, which focus on the knee, hip and ankle. CKCE are labeled as being "sport specific movements".

Shear force is the force which causes a disruption of the ACL by shifting the tibia anteriorly and the femur posteriorly. This is caused from the strong contraction of the quadriceps, which is typical of the Open Chain Exercise. This force, which is placed on the front of the knee, places a large amount of stress on the ACL. Compression force is caused from a strong external force placed on the knee, which pushes the head of the femur together with the head of the tibia. This external force causes stability in the knee and a decrease in shear force. Compression forces are common in Closed Chain Exercises.

Following ACL reconstruction, rehabilitation is the most important aspect of restoring the knee joint back to normal levels of competition. Over the past decade there have been a number of studies which focus on the rehabilitation of the ACL. Due to the extensive research in this field there is still differences in opinions among many people involved in the athletic community. Many state CKCE produces a minimal amount of shear force, while OKCE produces a great amount of shear force. Previous research performed comparing OKCE and CKCE found that CKCE was a safer and more beneficial from of exercise. Also they found that CKCE activated the hamstrings, which increase knee stability. Other research found that there was a large amount of quadriceps activity during both exercises. They found that strain place on the ACL during exercise is directly related to the shear force placed on the knee joint. During CKCE the hamstrings are contracted, which reduces anterior tibial displacement. In 1997, a research study found that there was no significant differences between OKCE and CKCE. In this study research indicates there is a place for both kinetic exercises during ACL rehabilitation.

Rehabilitation is the most important stage following ACL rupture. It is very important to understand what each form of kinetic exercise does to the knee joint. Coaches, trainers, physicians and therapists must understand the strain joint forces and torque place on the knee during each exercise. Also they must acknowledge which exercises cause stability, an increase in compression force, as well as increased ROM, which will benefit the patient during rehabilitation. The most important aspect is to return the athlete back to pre-injury competition level, as safe as possible. In order to do this exercises utilized must prevent re-injuring the repaired ACL. Thus the literature indicates that Closed Kinetic Chain Exercises are the most beneficial during rehabilitation of the repaired ACL. Also CKCE are the most beneficial exercises used for prevention of future injuries of the knee joint.