Interobserver reliability of the Gehweiler classification and treatment strategies of isolated atlas fractures: an internet-based multicenter survey among spine surgeons

Abstract

Purpose Atlas (C1) fractures are commonly rated according to the Gehweiler classification, but literature on its reliability is scarce. In addition, evaluation of fracture stability and choosing the most appropriate treatment regime for C1-injuries are challenging. This study aimed to investigate the interobserver reliability of the Gehweiler classification and to identify whether evaluation of fracture stability as well as the treatment of C1-fractures are consistent among spine surgeons. Methods Computed tomography images of 34 C1-fractures and case-specific information were presented to six experienced spine surgeons. C1-fractures were graded according to the Gehweiler classification, and the suggested treatment regime was recorded in a questionnaire. For data analyses, SPSS was used, and interobserver reliability was calculated using Fleiss’ kappa (κ) statistics. Results We observed a moderate reliability for the Gehweiler classification (κ = 0.50), the evaluation of fracture stability (κ = 0.50), and whether a surgical or non-surgical therapy was indicated (κ = 0.53). Type 1, 2, 3a, and 5 fractures were rated stable and treated non-surgically. Type 3b fractures were rated unstable in 86.7% of cases and treated by surgery in 90% of cases. Atlas osteosynthesis was most frequently recommended (65.4%). Overall, 25.8% of type 4 fractures were rated unstable, and surgery was favoured in 25.8%. Conclusion We found a moderate reliability for the Gehweiler classification and for the evaluation of fracture stability. In particular, diverging treatment strategies for type 3b fractures emphasise the necessity of further clinical and biomechanical investigations to determine the optimal treatment of unstable C1-fractures.

Effect of surgical experience and spine subspecialty on the reliability of the AO Spine Upper Cervical Injury Classification System

“…This is even more relevant when evaluating rare upper cervical spine injuries such as C1 and C2 ring injuries, which can be highly complex injuries that require accurate pattern recognition. 20 Furthermore, discussion on atlas injuries and C2 type B injuries is warranted given the moderate interobserver reliability when evaluated by orthopedic spine surgeons and neurosurgeons (the remaining injury subtypes received substantial or excellent interobserver reliability). Although the goal of an injury classification is to optimize its interobserver reliability (providing a framework for fa-cilitating future research, clinical discussion of injury patterns, and injury management guidance), the inherent rarity of certain injuries can make this challenging.…”

“…This is even more relevant when evaluating rare upper cervical spine injuries such as C1 and C2 ring injuries, which can be highly complex injuries that require accurate pattern recognition. 20 …”

“… 12 Even though the system is predominantly descriptive, the classification demonstrated moderate interobserver reliability (κ = 0.50), which is similar to the reliability of the AO Spine Upper Cervical Injury Classification System (range κ = 0.43–0.61). 20 Given that the AO Spine Upper Cervical Injury Classification System only has three injury types for atlas injuries compared with the five injury types for the Gehweiler classification, the AO Spine Upper Cervical Injury Classification System may be simpler to implement into practice. Further, the moderate reliability of both schemata indicates that atlas fractures may be inherently complex injuries to classify, and the "lower" reliability for C1 injuries may not be a shortcoming of the injury classification system itself.…”

Global Validation of the AO Spine Upper Cervical Injury Classification

“…Previous atlas fracture classifications have been proposed, but they have primarily been designed for descriptive purposes 1,6. Recently, Laubach et al 21 found the Gehweiler classification had moderate interobserver reliability (κ=0.50) when evaluated by 20 members of the German Society for Spine Surgeons, which was similar to the interobserver reliability obtained in our study when evaluating the AO Spine Upper Cervical Injury Classification (range: κ=0.45–0.60 for type IIA–IIC injuries on AS1 and AS2). Therefore, it appears plausible the complexity of atlas injuries account for the moderate classification reliability regardless of the classification schema applied to these injuries 22…”

The AO spine upper cervical injury classification system: Do work setting or trauma center affiliation affect classification accuracy or reliability?

“…2 Although this may be partially due to the inherent complexity of atlas fractures given that the reliability of the Gehweiler classification (a descriptive classification for atlas injuries) was recently demonstrated as moderate (k=0.50), our study suggests that minimal differences in classification accuracy or reliability exist for IIA or IIC injuries. 12 Instead type IIB injuries, which can be treated with divergent management pathways (conservative versus operative), may be uncommonly encountered and require additional trauma experience or tailored education to optimize classification accuracy. 13 Additionally, if surgeons choose to supplement CT scans with magnetic resonance imaging (MRI), additional information may be obtained which could improve the classification accuracy.…”