Ferenc Hepp is a specialist in sport medicine at the National Institute of Sports Medicine in Budapest, Hungary. He was member of the FIBA Medical Council.
About 60 to 80 percent of all sports injuries occur in the lower extremities. Among these, knee problems are the most frequent, followed by injuries of the talocrural (ankle) joint. Rupture of the anterior cruciate ligaments (ACL) of the knee belongs to the most serious of all sports injuries. After healing, athletes can continue their career, but, typically, at a much less competitive level. ACL ruptures occur most in soccer, basketball and handball, fast-paced sports that call for many changes of direction, jumping, and landing.
In most cases, ACL injuries are not caused by direct contact. In a recent medical survey, the three major causes of injury were:
- Stopping and change of direction - 19%
- Landing with the knee in extension - 28%
- Sudden stops - 26%
In basketball players, the ACL injury rate is particularly high, especially for females, where the female-tomale ratio is 4:1; the game to training ratio is 3:1. The higher ratio in female basketball players can be partially explained by the fact that their hip and knee flexion is smaller while stopping and changing direction as compared with males, which leads to diminished hamstring activity. On the other hand, ligament laxity, lower muscular strength and the different anatomical characteristics of the bones and muscles, in addition the diminished proprioception, can all be considered as causes of higher incidence of injuries in women.
Mechanisms of ACL injuries:
- In hyperextension, the ligament is pressed to the upper part of the osseal intercondylear space, resulting in breaking and tearing by stronger forces.
- Through rotation-valgus stress, the distance between the origin and insertion increases and the ligament is stretched and torn.
- In sudden stops, the quickly stretched quadriceps muscle pushes the tibia into an anterior subluxation, causing the rupture of the ligament.
Diagnostic examinations for ACL injuries:
1. The AD test
The knee is bent to 80 degrees. The examiner sits on the patient’s leg and examines the tone of knee flexion muscles. The examiner uses both hands under the knee, and pulls it into the anterior direction and the range of this anterior shift is estimated in the tests.
2. The Lachmann test
The examiner holds the leg with the same hand (right or left) as the lower limb, and above the knee with the other hand. In this position, the examiner tries to pull the tibia forward in about 20 to 30 degrees of knee flexion. The test is estimated by the range of pathologic movement.
For the past 20 years, orthopedic researchers have studied proprioceptors within the joints. Proprioception is the conscious and unconscious ability that enables us to perceive our different body parts engaged in space. The normal function of a joint is maintained by stabilization, both passively-with ligaments-and actively- with muscles. Ligaments are able to stretch by about 5 percent of their normal length. If they are stretched any further, rupture occurs. This lengthening is immediately identified by the receptors, and the muscle stretch attempt to relieve pressure on the ligaments through the proprioceptive reflex circles. This is the main reason that muscle strength plays a distinctive role in the prevention of ligament injuries!
In the case of an ACL rupture, muscles are not able to compensate the force over tensile strength. The harmonizing action of agonist and antagonist muscle groups is disturbed here. Their co-ordination can be enhanced by proprioceptive neuromuscular facilitation. These special exercises include standing in one leg on flat surface, as well as on a tilting plateau. Another popular exercise is to step up and down from a globe-based plateau.
This special proprioceptive training should be started 30 days before the competitive season begins.
The exercises should be performed 20 minutes a day, three times a week, during the competitive season. Although the method seems to be theoretically correct, the overall effectiveness of the exercises has varied.
Many ACL injuries can be prevented once you understand the extrinsic and intrinsic factors that influence sport injuries.
Major extrinsic risk factors include:
- Specific features of the sports activity, such as the rules of the game, demands of physical training, level of sport activity, sport movements (stopping, changing direction, jumping, and landing);
- The type of playing surface area and sport facility;
- The role of the coach and sport physician;
- Dietary habits.
Major intrinsic risk factors include:
- Physical and psychosocial features (anatomical variation, muscle balance, flexibility, co-ordination, and stress);
- Previous injuries;
- Level of skill in the sport;
- Characteristic personality features.
Sports proficiency is based, for the most part, on an athlete’s physical conditioning.
The best way to prevent ACL injuries is to be aware of the risk factors. I have noted and taking all appropriate steps to minimize injury. A recent medical survey reported that the frequency of ACL injuries could be diminished by 89 per cent with the use of the “three-step stop” with the knee bent instead of one-step stop with the knee hyperextended-all techniques designed to decrease the quadricepscruciate interaction.
In summary, ACL injuries are of great concern. Therefore, efforts to prevent or at least decrease the rate of occurrence of these injuries seem wise. Neuromuscular control and balance, as well as avoidance strategies for at-risk situations, are critical factors for injury prevention.
Prevention programs designed to increase neuromuscular control, improve balance, and teach avoidance strategies appear to be effective in decreasing injury rates.