{'fraction_non_alphanumeric': 0.029694323144104803, 'fraction_numerical': 0.022707423580786028, 'mean_word_length': 4.617647058823529, '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}}
The effectiveness of active head restraint in preventing whiplash.

BACKGROUND
Whiplash injury claims have increased for two decades and manual head restraints are often incorrectly adjusted. A Self-Aligning Head Restraint (SAHR) was designed to move upward and forward by occupant motion in a rear crash providing earlier neck support, even when the head restraint is positioned low. This study determines its field effectiveness.


METHODS
Insurance records were analyzed for consecutive Saab rear crashes in Sweden over 18 months. The Saab 9000/900 had standard head restraints and Saab 9-5/9-3 had SAHR. A questionnaire was mailed to the occupants, insurance and medical records were reviewed, and phone interviews were conducted.


RESULTS
SAHR reduced whiplash injury risks by 75 +/- 11% from an 18 +/- 5% incidence in 85 occupants with standard head restraints to 4 +/- 3% in 92 occupants with SAHR. No SAHR seat required repair or replacement after the crashes.


CONCLUSION
SAHR is effective in reducing whiplash injury in rear crashes and is a passive public-health approach that works irrespective of manual head-restraint adjustment.