CLASSIFICATION OF SOFT TISSUE INJURY
Ligament injury is classically divided into first (mild), second (moderate), and third (severe) degree tears. In a few locations, e.g., the acromioclavicular joint, there is further classification of the degree of displacement and the amount of associated muscle trauma, but these joints are the exception.
First degree injuries entail microscopic stretching or minimal tearing of a few fibers of a ligament. It is a painful injury, but there is little loss of structural integrity. The treatment progress is guided mainly by the athlete’s pain, with anticipated return to full physical activity within 10 days to 2 weeks. Indeed, controlled training may be carried out even before this point. Early protection of the joint with taping or orthoses may be desirable, and frequently little or no interruption of training is necessary.
It is the second degree injury, with moderate tearing of the ligament’s collagenous fibers and some loss of structural integrity, that usually presents the most difficulty for accurate classification. In part it is because the second degree category encompasses a broad spectrum of injury. At the one extreme there is an injury similar to a first degree sprain and at the other a badly torn ligament that is bordering on complete disruption. Underestimating this second degree injury and thus allowing premature resumption of activity may lead to re-injury or possibly conversion to a third-degree situation. Conversely, overestimation of the severity gives rise to unnecessary loss of time from training. These clinical decisions are always difficult, and there is no substitution for the physician’s experience.
In general, second degree tears require 2 to 3 weeks of modified rest and rehabilitation, followed by 2 to 3 weeks of controlled introduction of increasing stress before full training is resumed. It may be as long as 2 to 3 months before full training and competition are allowed, depending on the joint involved, the magnitude of the disruption, and the requirements and stresses of the sport. The more severe second degree tears, along with the third degree injuries, may have a tendency for the healed ligaments to stretch out with time, leading to increasing functional instability, despite excellent rehabilitation and satisfactory early stability.
A third degree injury signifies complete tearing of the ligament with loss of structural integrity. In many situations, it requires complete or modified immobilization of the involved joint for a period of 3 to 6 weeks and frequently surgical intervention. Failure to treat these third degree disruptions adequately lead to recurrent instability and possibly degenerative changes of the involved joint. This long-term implication of degenerative articular surface pathology in inadequately treated or incompletely healed major weight-bearing joints cannot be overemphasized.
It has already been stressed that each structure has an anticipated healing time, and that one cannot accelerate the normal recuperative abilities of the tissues. Therefore, therapy is aimed at optimizing healing conditions. With extra articular collagenous structures, ligamentous strength after tearing is in the region of 60 to 70 percent of normal after 6 weeks of healing. More specifically, there is often a revascularization phase during healing that is usually accompanied by a dramatic reduction of tensile strength. Because this phase usually coincides with the period during which most external supports have been removed, it is mandatory that the physician be aware of the dangers of unduly stretching healing structures at this point. It requires considerable knowledge and skill to balance exercise progression with protection of the vulnerable tissue. It may take up to 3 months before 80 percent of the original strength is acquired. Intra-articular ligaments usually gain tensile strength more slowly. Healing times for intra-articular collagen are such that it may take up to 3 months to achieve 50 percent of the normal strength and 6 months before a functional strength of 70 percent is reached. The reintroduction of stress to the unprotected joints must be planned with these figures in mind. Furthermore, although little is known of the effects of ligament tears on the neural protective mechanism of joints, it is likely that after significant tears there is a distorted or decreased biofeedback. Particularly for the major weight bearing joints, such as the knee and ankle, some specific exercises are needed to either retrain or compensate for this potential loss of sensory information.