The Prevalence of Spondylolysis in Athletes
Abstract & Commentary
Synopsis: Torsion against resistance, such as with throwing sports in track and field, was found to be a risk factor for spondylolysis. Soler and Calderon feel that athletes in high-risk sports should be radiographically screened.
Source: Soler T, Calderon C. The prevalence of spondylolysis in the Spanish elite athlete. Am J Sports Med 2000;28:57-62.
Spondylolysis, a bony defect in the posterior elements of the spine, has been associated with lumbar hyperextension and is a potential source of back pain in athletes. The average prevalence of spondylolysis in the general population has been determined to be between 3.5% and 7%. When athletes are analyzed as a separate population, the incidence has ranged from 12% to 32%. One major shortcoming of the previous studies involving athletes has been that screening has been performed on symptomatic individuals only. This may exaggerate the true incidence of spondylolysis in the athletic population. Soler and Calderon offer a more accurate representation of the true incidence of spondylolysis in the athletic population by prospectively reviewing 3152 high-level Spanish athletes with or without symptoms. All of these subjects were involved in preparticipation physicals as part of their governmentally supported training program in Spain. All patients underwent history and physical examinations as well as posterior-anterior and lateral standing lumbar spine x-rays. When in question, additional oblique projections were obtained and, in rare cases, bone scans or magnetic resonance images (MRIs) were performed.
The subjects’ average age was 21 years and men outnumbered women 2:1. The cases of spondylolysis were identified radiographically and only definite cases with clear evidence of lysis were included. The incidence of spondylolysis was correlated with the athletic event of the individual to ascertain risk factors.
A total of 253 of the 3152 athletes had spondylolysis, for an incidence of 8% (95% confidence interval, 7-9%). In 30% there was additional evidence of slippage or spondylolisthesis. Interestingly, spondylolisthesis was more common among women (41%) as compared to men (25%) despite the overall incidence of spondylolysis not being significantly different between men and women. The great majority of spondylolysis occurred at the L5 level (84%).
Activities correlating with the greatest risk of spondylolysis included those involving lumbar hyperextension and rotation, such as gymnastics (17%) and rowing (17%). Soler and Calderon add a new observation that athletes involved in throwing sports in track and field, such as shot put, discus, javelin, and hammer throw actually have the highest prevalence of spondylolysis, at 27%. It is interesting to note that less than half of all athletes with spondylolysis were symptomatic; however, two-thirds of the throwing athletes experienced symptoms.
Comment by David R. Diduch, MS, MD
Soler and Calderon have provided us with useful new information for screening for spondylolysis among competitive athletes. This is the first prospective study to randomly screen all athletes participating at an elite level. As such, it provides a better measure of the true incidence of spondylolysis in the athletic population. Their numbers are large, yielding a narrow 95% confidence interval in support of their findings. Although the overall incidence of spondylolysis of 8% was only slightly higher than the 3.5-7% found in the general population, when they analyzed individual sports, significant differences were detected. In addition to the usual mechanisms of lumbar hyperextension and rotation, Soler and Calderon add the mechanism of throwing or torsion against resistance as another possible causative factor for spondylolysis.
Team physicians and trainers should be aware that athletes participating in torsion against resistance, such as track and field throwing sports, are at a greater risk for spondylolysis. Although Soler and Calderon recommend prospective radiographic screening for all athletes engaged in high-risk sports, that conclusion is not supported by the findings of this study per se. Because less than half the patients were symptomatic, one cannot assume that just because they have spondylolysis radiographically that treatment or change in activity is necessary. The paper made no attempt to analyze clinical results or treatment outcomes and should not be misinterpreted as such. However, I do believe the paper offers useful information that should heighten the trainer’s or physician’s suspicion for spondylolysis for given sports and has helped us to identify a new subgroup of athletes at risk.
Which of the following activities were found in the study by Soler and Calderon to put athletes most at risk for spondylolysis?
a. Gymnastics
b. Throwing sports in track and field (shot put, discus)
c. Baseball pitching
d. Football—interior linemen
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