{'fraction_non_alphanumeric': 0.026630434782608695, 'fraction_numerical': 0.014130434782608696, 'mean_word_length': 4.8630573248407645, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Degenerative changes of the spine of fighter pilots of the Royal Netherlands Air Force (RNLAF).

HYPOTHESIS
The aim of this study was to examine whether F-16 pilots are at an increased risk of (cervical) spine degeneration.


METHOD
Retrospectively, X-ray slides were examined of pilots of the Royal Netherlands Air Force who were systematically radiographed (at least twice). In total, 316 pilots were evaluated: 188 F-16 pilots and 128 pilots in the control group. Two radiologists, who were blinded as to whether the X-ray films were of F-16 pilots or the control group, examined these X-rays separately. In both groups, the time between the two X-rays was on average 6 yr.


RESULTS
Though the inter-rater agreement of the X-rays was rather low, both radiologists found comparable statistically significant differences between the two groups. In the F-16 group, an increased osteophytic spurring was found at levels C4-C5 and C6-C7, and increased arthrosis deformans was found in the cervical spine. Further analysis of the data of a selected group of pilots, whereby the difference in age between both groups was minimized, showed that the higher mean age of the F-16 pilots was possibly correlated with the increased degeneration in this group. No consistent relationship was found between spinal degeneration and initial radiological status. Also, a clear relationship between spinal degeneration and flying hours could not be demonstrated.


CONCLUSION
These findings suggest that frequent exposure to high +Gz forces might cause premature degeneration of the spine of F-16 pilots. Future research must demonstrate to what extent age, mission, and number of flying hours have influenced the results. An uniform international classification and coding system in combination with establishing an international database is recommended.