Data about the degenerative changes of the cervical spine in athletes and particularly Olympic athletes is fairly limited [6, 7, 17,18,19,20,21]. Our study is the first to assess the cervical DDD in Olympic athletes who obtained imaging. Nearly 58% of the cervical discs of the examined athletes demonstrate some degree of degeneration: 75% were classified as mild and 25% as moderate to severe. The percentage of DDD of the cervical spine in our study was significantly higher than other studies of symptomatic and asymptomatic non-athletes of the same age groups. For instance, Boden et al. conducted an MRI study of the cervical spine in 63 asymptomatic subjects and reported that the disc was degenerated or narrowed at one level or more in 25% of subjects who were less than forty years old [22]. In another study involving 497 asymptomatic volunteers, Matsumoto found disc degeneration was the most common observation, being present in 17% of discs of men and 12% of women in their twenties [23]. Suzuki et al. evaluated cervical disc degeneration on MRI in a large population of symptomatic consecutive patients reporting neck pain or radiculopathy with or without neurologic deficits. The prevalence of cervical disc degeneration at more than 1 level was 41.0% in patients in their 20s [24]. Siivola showed that 25% of the cervical discs were degenerated in young adults with or without neck or shoulder pain of which 83% were classified as slightly degenerated and 17% as moderately degenerated [25].
Cervical degenerative changes were predominantly seen in men and above 30 years of age in our study. Shooters and Judo athletes were the most affected by mild DDD in our study whereas athletics, boxers and swimmers were the athletes most affected by moderate DDD. DDD was seen at an earlier age group (between 20 and 30 years of age) in swimmers which may be secondary to the increased mechanical stress on the cervical spine sustained when swimming [26]. On the other hand, DDD was only seen above 30 years of age in Athletics and Boxing athletes. Most of the degenerative discs were seen at the C5-C6 and C6-C7 levels where the fulcrum for maximal cervical spine movement is located [27].
At the thoracic spine, only mild degenerative changes were observed (12%). These changes were noted in female gymnastics and divers between 20 and 30 years of age. No moderate or severe DDD was noted at the thoracic level which may be secondary to the stability of the thoracic spine by the thoracic cage and the reduced mechanical stress on the thoracic intervertebral discs when compared to the cervical and the lumbar spine [17, 28].
At the level of the lumbar spine, nearly 39% of the lumbar discs demonstrated some degree of degeneration with two thirds of them classified as mild and one third as moderate or severe degeneration. Although lumbar disc degeneration is a common imaging finding in asymptomatic and symptomatic young individuals, our study showed that Olympic athletes have higher prevalence of moderate to severe disc degeneration than non-athletes [14, 29,30,31]. Even with the wide variation related to sample sizes, different age ranges, different clinical presentation, and different criteria and classification of the degenerative changes, our results are in accordance with several prior studies that showed the higher rate of these degenerative changes of the lumbar spine in athletes [1, 2, 6, 32,33,34,35]. For instance, Ong et al. studied the degenerative changes in elite athletes with lower back pain at the Sydney 2000 Olympic Games and showed degenerative changes of 36% of the discs at the L5/S1 level which is comparable to our study [6].
L4–5 and L5-S1 were the most commonly affected levels. Athletics were the most common athletes affected by DDD, followed by weightlifting and diving, respectively. The higher rate of degenerative changes in these sports is believed to be secondary to the repetitive, strenuous, and intense training required by the athletes to compete in the Olympic Games. For instance, Athletics are consistently exposed to considerable axial loading, flexion, and rotation that stresses the lumbar spine. Divers are also exposed to repetitive axial compression forces to the top of the head that may be transmitted caudally to the lumbar spine. Weightlifters sustain an increased axial loading across the entire thoracolumbar spine associated with an increased loading during the repetitive flexion and extension bending movements [36, 37].
Furthermore, our study showed that women athletes demonstrated a tendency for a higher rate of DDD in the lumbar region in contrast of what is reported in non-athletes at the same age groups where young men were more susceptible to disc degeneration than young women [29, 38, 39]. .This is likely related to the excessive mechanical stress and physical injury sustained by young elite women athletes.
In contrast of what our study noticed in the cervical spine where the degenerative discs were more frequently noted in athletes above 30 years of age, nearly 40–50% of the degenerative lumbar discs were noticed at an earlier age (i.e less than 30). This may be due to the fact the lumbar spine is the recipient of the heaviest biomechanical stress and is likely to be involved by degenerative disease earlier than the cervical spine.
Our results should be interpreted with caution and in the context of the patient’s clinical condition since more than one third of normal healthy subjects aged 21–30 years had degenerative discs in one study [40]. Furthermore, MRI-detectable abnormalities associated poorly with back pain in high-performing athletes [41].
The present study has several limitations. The descriptive and the retrospective nature of our study and the absence of detailed clinical correlation of the participant athletes are the main drawbacks. There is also a selection bias since the participants included in our study were not randomly selected and do not represent all the athletes. There may also be high prevalence of mild to moderate DDD in asymptomatic athletes which may not be detected because not all athletes had MR imaging. In addition, being a descriptive study, statistical significance was not calculated. Pfirrmann classification used in our study does not cover other morphological changes of the degenerative disease like endplate changes, osteophytes formation, disc protrusion or herniation, foraminal or spinal narrowing. Its extrapolation to the cervical and thoracic spine is also considered a shortcoming of our study.