Relationship between localized spine deformation and cervical vertebral motions for low speed rear impacts using human volunteers

Ono, Koshiro; Inami, Satoshi; Kaneoka, Koji; Gotou, Tukasa; Kisanuki, Yoshikatu; Sakuma, Shigeru; Miki, Kazuo

It is important to more clearly identify the relationship among the rampingup motion, straightening of the who!s snine. and c.:c?n/ic~r.ve!rtehrae motion in order to clarify minor neck injury mechanism. The aim of the current study is to verify the influence of the change of the spine configuration on human cervical vertebral motion and on head/neck/torso kinematics under low speed rear-end impacts. Seven healthy human volunteers participated in the experiment under the supervision of an ethics committee. Each subject sat on a seat mounted on a sled that glided backward on rails and simulated actual car impact acceleration. impact speeds (4, 6, and 8 km/h), and seat stiffness (rigid and soft) without headrest were selected. During the experiment, the change of the spine configuration (measured by a newly developed spine deformation sensor with 33 paired set strain gauges and placed on the skin) and the interface load-pressure distribution was recorded. This was measured by means of a Tekscan system at a rate of 100 f/s, placed between the seat and subject. The cervical vertebrae motion was also recorded by 90 f/s cineradiography. Furthermore, analysis was made to quantify the relationship between the cervical vertebrae motion and the change of the spine configuration.

The localized straightening of the lumbar spine starts at around 30 ms with the rigid seat. The localized straightening of the thoracic spine reaches the maximum at around 80 ms when the load-pressure distribution is at its peak value due to the interaction between the shoulder and the seatback. On the other hand, for the softer seat, the pelvis starts to sink into the seat back and cushion at around 70 ms. As for such seat the load-pressure is distributed over a large area, the localized straigthening of the middle thoracic spine occurred together with deflection of seatback itself at around 120 ms. The results of this study can help clarify the relationship between the localized straightening of the spine and cervical vertebrae motion with respect to the difference in seat characteristics.

Year

Entry

1998

Ono K, Kaneoka K, Inami S. Influence of seat properties on human cervical vertebral motion and head/neck/torso kinematics during rear-end impacts. In: Proceedings of the 1998 International IRCOBI Conference on the Biomechanics of Impact. September 16-18, 1998; Göteberg, Sweden.303-318.

1998

Shen W, Wiklund K, Frid S, Swamy B, Nilson G, Humer M. Pressure and load patterns on seat interface: a comparison between human subjects and crash test dummies. In: Proceedings of the 1998 International IRCOBI Conference on the Biomechanics of Impact. September 16-18, 1998; Göteberg, Sweden.453-464.

1994

Ishiyama S-i, Tsukada K, Nishigaki H, Ikeda Y, Sakuma S, Matsuoka F, Kanno Y, Hayashi S. Development of an abdominal deformation measuring system for Hybrid III dummy. In: Proceedings of the 38th Stapp Car Crash Conference. October 31–November 2, 1994; Fort Lauderdale, FL. Warrendale, PA: Society of Automotive Engineers:265-279. SAE 942223.

1997

Ono K, Kaneoka K, Wittek A, Kajzer J. Cervical injury mechanism based on the analysis of human cervical vertebral motion and head-neck-torso kinematics during low speed rear impacts. In: Proceedings of the 41st Stapp Car Crash Conference. November 13-14, 1997; Lake Buena Vista, FL. Warrendale, PA: Society of Automotive Engineers:339-356. SAE 973340.

1983

Nygren Å. Injuries to car occupants: some aspects of the interior safety of cars: a study of a five-year material from an insurance company. Acta Oto-Laryngol. 1983;95(suppl 395):1-135.