Children and adolescents are more frequently training and competing in the same sport or multiple sports on a nearly year-round basis. Involvement in activities outside of the traditional scholastic and community-based settings, such as sport clubs, camps, and the hiring of personal coaches, has become widespread. Given this trend, overuse injuries among children and adolescents have become more common.
As yet, the long-term consequences of overuse injuries in growing children have not been well studied. Although it has been estimated that 50% of overuse injuries in children are preventable, there is little research that identifies specific preventive measures. In fact, the American Academy of Pediatrics recently published a statement on training and sports specialization in youth that highlighted the need for further investigation in this area.
Chronic wrist pain in young gymnasts is an injury that illustrates many of these issues. Gymnastics remains a popular activity among American youth, with millions of children and adolescents participating at recreational and competitive levels. Learning gymnastics skills requires the performance of repetitive movements that frequently employ the upper extremities as weight-bearing limbs. As a consequence of this, wrist pain is common among gymnasts. Because most children enter the sport at a young age, the growth plates of the wrist are a potential site of injury. In fact, radiographic surveys have established that stress injury of the distal radial physis occurs in young gymnasts.
In addition, skeletally mature elite gymnasts have been reported to display a greater prevalence of positive ulnar variance, in which the length of the distal ulna exceeds that of the distal radius by 1 mm or more. Because positive ulnar variance can lead to chronic degenerative conditions of the wrist, there is concern regarding the long-term consequences of this finding in gymnasts.
These observations have led some to propose that in some gymnasts with chronic wrist pain, stress injury to the distal radial physis may occur and cause disruption in growth of the distal radius. This, perhaps coupled with stimulation of the ulna via repetitive loading, may result in the development of positive ulnar variance. Several case reports that appear to document premature closure of the distal radial physis have been cited to support this concept. Alternatively, others consider ulnar variance to reflect genetic factors rather than an acquired condition.
Mechanism of Injury
During gymnastics training, the wrist joint is exposed to forces and rates of loading that far exceed body weight. The wrist is usually loaded in a dorsiflexed position, and additional stress applied with associated movements of radial or ulnar deviation. Anatomic studies of adult cadaver specimens demonstrate that in a neutral position the distal radius bears approximately 80% of the load presented to the wrist joint. If the ulna is shortened by 2.5 mm, the load borne by the distal radius increases to 96%. This is relevant to the young gymnast because the skeletally immature wrist displays a negative ulnar variance of slightly more than 2 mm. This characteristic may explain the propensity for distal radial physeal injury to occur in young gymnasts.
Prevalence and Characteristics
The prevalence of wrist pain among gymnasts ranges from 46% to 79%. The problem is not limited to elite or highly advanced performers, as more than 50% of gymnasts participating at beginning and middle skill levels are affected. Importantly, these youngsters comprise the vast majority of gymnasts in the United States.
Recent studies have provided a collective profile of the young gymnast with wrist pain. Skeletally immature gymnasts have wrist pain with training that is dorsally located and aching in quality. Events that include a combination of elements that stress the joint, such as the floor exercise, pommel horse, and balance beam, are the most frequently associated with wrist pain. After adjusting for age, training volume, and skill level, there is no difference in the prevalence of wrist pain among boys and girls. Most gymnasts affected do not have pain with nongymnastics activities. They are often able to continue training, though pain may affect the extent of their participation. Even so, the pain is not self-limited. Most describe pain that has been present for several months. And a recent observational study found that the vast majority of young gymnasts who initially described wrist pain continued to have symptoms when surveyed 1 year later.
Causes of Chronic Wrist Pain
Chronic wrist pain in young gymnasts has many possible causes. Dorsal impaction syndromes can involve the dorsal rim of the radius, dorsal scaphoid, or lunate. Radiographs can demonstrate ossicle formation at these sites, best seen on the lateral view. Dorsal impingement (wrist capsulitis) is perhaps a diagnosis of exclusion. Gymnasts with this injury present with diffuse dorsal wrist pain and negative radiographic findings. MRI in these cases may be helpful to exclude physeal injury or occult ganglia.
Ulnar-sided wrist pain is more common among older gymnasts who, as discussed above, may develop positive ulnar variance, predisposing to ulnar impaction syndrome and tears of the triangular fibrocartilage complex. Although young gymnasts may display an ulnar variance that is relatively more positive than that seen in nongymnasts, the absolute ulnar variance is typically negative, and ulnar-sided wrist pain is less frequent.
Perhaps the most common form of chronic wrist pain in young gymnasts is stress injury of the distal radial physis. Repetitive loading of the wrist is thought to interfere with the ossification process by disrupting metaphyseal vessels. This results in the persistence of chondrocytes in the hypertrophic zone, while cell division continues in the proliferative zone, leading to widening of the growth plate. Radiographic criteria include 1) haziness within the normally lucent growth plate, 2) cystic changes and irregularity along the epiphyseal and metaphyseal borders of the physis, 3) a beaked appearance of the radial aspect of the metaphysis, and 4) widening of the physis. Radiographic findings of physeal injury have been reported in 8% to 85% of elite gymnasts and 25% to 50% of beginning to mid-level gymnasts. MRI appears to be a more sensitive and specific method for detecting growth plate injury in gymnasts, although controlled studies are currently lacking. Some gymnasts with negative radiographic findings may have positive findings on MRI, which suggests that the prevalence of physeal injury in gymnasts with wrist pain is likely greater than that described in the radiographic surveys that are currently available.
Although it is clear that repetitive loading of the wrist causes chronic wrist pain, not all gymnasts who train regularly develop symptoms. Studies of young gymnasts have identified several specific factors that appear to contribute to the development of this condition.
Compared with gymnasts who are pain-free, those with wrist pain are older, initiate training at an older age, and train at a higher skill level for more hours per week. Intensity factors incorporating both skill level and weekly training time have found greater intensity levels to be associated with wrist pain.
The phase of growth may also play an important role. Gymnasts between 10 and 14 years of age are significantly more likely to have wrist pain when compared with those below or beyond this age range. Given that peak growth velocity occurs at 12.5 years of age for female gymnasts and 13.6 years for active boys, this suggests that the period of the adolescent growth spurt imparts additional risk for the development of wrist pain. This is supported by experimental and clinical studies that demonstrate an increased risk of physeal injury during the period of rapid growth.
Indirect measures of cumulative loading such as years of training and self-reported exposure time have not been shown to be associated with wrist pain when multivariate analysis is applied. Factors such as coaching technique, equipment, and nutritional status have not been well studied.
Relationship Between Wrist Pain, Distal Radial Physeal Injury, and Ulnar Variance
Longitudinal studies demonstrating a sequential relationship between wrist pain, distal radial physeal injury, and ulnar variance are limited. A single study of elite Chinese gymnasts followed over a 9-year period did report progression of symptoms and radiographic findings ultimately resulting in positive ulnar variance in 50% of subjects.
Among nonelite gymnasts, there does appear to be a direct relationship between the extent of radiographic findings of distal radial physeal injury and symptoms of wrist pain. With respect to ulnar variance, although in skeletally immature gymnasts ulnar variance is relatively more positive than in nongymnasts, most measurements fall within the range of normal. In addition, positive ulnar variance has not been shown to be associated with wrist pain or radiographic findings of distal radial physeal injury in skeletally immature gymnasts. In fact, the opposite may be the case. Because absolute ulnar variance is negative, those with more negative ulnar variance tend to be predisposed to wrist pain and distal radial physeal injury, as the load-sharing of the distal radius increases. Upon skeletal maturity, such individuals may develop positive ulnar variance due to inhibition of growth of the radius, but data describing this are limited to a few case studies and the single cohort described above.
Chronic wrist pain in young gymnasts is an example of an overuse injury that can affect the physis. Yet, it remains unclear the extent to which this injury results in altered growth of the wrist leading to positive ulnar variance and its sequelae. Although these findings are unique to young gymnasts, there are several other examples of similar overuse injuries involving the physis including those of the proximal humerus, proximal tibia, and distal femur. In addition to these clinical descriptions, basic science studies have also described the negative effects of high intensity loading on immature bone.
The data summarized above provide a clinical model that an important issue that surrounds intensive training of skeletally immature athletes. Though the data remain somewhat limited, they highlight the important role of training intensity and the vulnerable period of the adolescent growth spurt in the genesis of overuse injuries. Further studies are needed to determine the long-term consequences of these findings, and also to delineate specific preventive measures, such as the modification of training during periods of rapid growth, that will reduce the occurrence of overuse injuries in young athletes.