RESUMO
BACKGROUND: The reported prevalence of spondylolysis (SL) in the adult population is 6-7%. Data concerning adolescent-onset spondylolisthesis (SLS) and the impact of certain activities on it is scarce. We examined the risk of clinical progression of SL and SLS as a function of primary severity and occupational strain among military recruits. METHODS: Based on the Israel defense Force (IDF) central human resources database, we identified 1521 18-year-old males inducted to the IDF with SL/SLS between the late nineteen nineties and early two-thousands. We followed changes in the SL/SLS status during the 3 years of obligatory military service. Disease severity was classified as Cat2: radiological findings of SL without clinical findings; Cat3: painful SL or asymptomatic grade 1 SLS; Cat4: grade 1 SLS with pain; Cat5: Grade 2 SLS. The soldiers were subdivided into the following occupational categories: administrative, combat, maintenance, and driving. The purpose was to compare the progression rates in different medical categories and job assignments. RESULTS: There were 162 recruits in Cat2, 961 in Cat3, and 398 recruits in Cat4. The overall progression rate to Cat5 (grade 2 SLS) was 1.02%. Significant progression rates were seen amongst administrative soldiers with a relatively higher risk of progression from Cat4 (painful-grade-1 SLS: 2.2%) vs. Cat3 (asymptomatic SLS: 0.5%, relative risk = 4.7, p < 0.02). Other occupational categories did not exhibit significant progression rates. CONCLUSION: Progression of SL/SLS was highest in Cat4, i.e. for recruits already diagnosed with painful SLS (i.e. with a more severe baseline disorder). Progression did not correlate with military occupation. We recommend further follow-up studies that include, aside from progression rates, incidence rates of newly diagnosed grade 2 SL during military service.