Addition of lateral bending range of motion measurement to standard sagittal measurement to improve diagnosis sensitivity of ligamentous injury in the human lower cervical spine

Improving the staging of neck injuries using a new index, the Neck Functional Holistic Analysis Score: Clustering approach to determine degrees of impairment

Background

Traumatic cervical spine injuries are amongst the traffic injuries that can cause most harm to a person. Classifying subtypes of clinical presentations has been a method used in other pathologies to diagnose more efficiently and to address the appropriate treatment and the prognosis. The management of patients suffering from cervical injuries could be improved by classifying the severity of the impairment. This will allow clinicians to propose better treatment modalities according to the severity of the injury.

Materials and methods

The present study is a retrospective cohort study performed with the clinical data from 772 patients stored at Fisi-(ON) Health Group. All the patients treated for cervical spine injuries are evaluated using the EBI-5^® system, which is based on inertial measurement unit (IMU) technology. The normalized range of motion of each patient was incorporated into a single index, the Neck Functional Holistic Analysis Score (NFHAS).

Results

Clustering analysis of the patients according to their NFHAS resulted in five groups. The Kruskal-Wallis H test showed that there were statistically relevant differences in the ROM values and NFHAS of the patients depending on the cluster they were assigned to: FE X²(4) = 551.59, p = 0.0005; LB ROM X²(4) = 484.58, p = 0.0005; RT ROM X²(4) = 557.14, p = 0.0005; NFHAS X²(4) = 737.41, p = 0.0005. Effect size with ηp² for the comparison of groups were: FE = 0.76, LB = 0.68, RT = 0.76 and NFHAS = 0.96.

Conclusion

The NFHAS is directly correlated to the available ROM of the patient. The NFHAS serves as a good tool for the classification of cervical injury patients. The degree of impairment shown by the cervical injury can now be staged correctly using this new classification.

[The biomechanics of hyperextension injuries of the subaxial cervical spine]

Hyperextension injuries of the subaxial cervical spine are potentially hazardous due to relevant destabilization. Depending on the clinical condition, neurologic or vascular damage may occur. Therefore an exact knowledge of the factors leading to destabilization is essential. In a biomechanical investigation, 10 fresh human cadaver cervical spine specimens were tested in a spine simulator. The tested segments were C4 to 7. In the first step, physiologic motion was investigated. Afterwards, the three steps of injury were dissection of the anterior longitudinal ligament, removal of the intervertebral disc/posterior longitudinal ligament, and dissection of the interspinous ligaments/ligamentum flavum. After each step, the mobility was determined. Regarding flexion and extension, an increase in motion of 8.36 % after the first step, 90.45 % after the second step, and 121.67 % after the last step was observed. Testing of lateral bending showed an increase of mobility of 7.88 %/27.48 %/33.23 %; axial rotation increased by 2.87 %/31.16 %/45.80 %. Isolated dissection of the anterior longitudinal ligament led to minor destabilization, whereas the intervertebral disc has to be seen as a major stabilizer of the cervical spine. Few finite-element studies showed comparable results. If a transfer to clinical use is undertaken, an isolated rupture of the anterior longitudinal ligament can be treated without surgical stabilization.