Abstract
Objective
The purpose of this study is to describe and validate a CT based classification of lumbosacral segment abnormalities.
Method
400 CT scans were retrospectively reviewed, a classification devised and incidence of abnormalities recorded. 5 types of abnormality were identified. Type 0 is normal; Type 1 describes an asymmetrical shortening of the iliolumbar ligament; Type 2's have the transverse process of L5 within 2 mm of the sacrum but not forming a joint; Type 3's have formed a diarthrodial joint, with 3A's showing no evidence of degeneration and 3B's displaying degenerative changes; In type 4's the transverse process and sacrum have fused; Type5's have involvement of L4. In order to validate the classification, 40 scans were selected with a full cross section of types. 4 independent observers classified each scan in 2 separate sessions, 2 weeks apart.
Results
In the study population there was an abnormality in 54.5% of individuals. In order to validate the classification the intra-observer and inter-observer ratings were analysed. The kappa values for the intra-observer results were between 0.69 and 0.88, indicating substantial agreement (using the Landis and Koch kappa interpretation). The results for inter-observer ratings also gave a combined score of over 0.7 for both sessions, again indicating substantial agreement.
Conclusion
A CT classification of lumbosacral segment abnormalities, which is both straight forward to use and repeatable, has been produced. The incidence of these abnormalities is higher in our population of CT scans compared to previous published series using plain radiographs.
Ethics approval Audit/service standard in trust
Interest Statement: None
