Moderate to Substantial Inter-Rater Reliability in the Assessment of Cranial Bone Mobility Restrictions

The World Health Organization benchmarks for osteopathic training consider cranial osteopathy as an important manual skill. Studies of cranial manual therapy have exhibited poor reliability. The aim of this study was to investigate the inter-rater reliability of the manual mobility tests of the spheno-occipital synchondrosis (SOS), and the temporal, parietal, and frontal bones, as assessed in osteopathic manual therapy. Twenty-one adults were assessed on a single day by three experienced osteopaths using a standard assessment protocol. Before data collection, the osteopaths participated in a consensus training, which included establishing the criteria for identifying a cranial bone mobility restriction; the application of the seven-step palpation method; a pretesting practice; a fine-tuning palpation training; and a calibration period before the assessment of the subjects. Three subjects were assessed simultaneously with the evaluators rotating to assess each subject. The evaluators were blinded to the subject by a curtain, and each other's assessments. Each bone was rated as restricted or not restricted. The authors applied the Landis and Koch classification to describe the magnitude of inter-rater reliability. Moderate reliability was established for a lateral strain of the SOS (Fleiss' generalized kappa 0.48), substantial reliability was established for the other SOS strain patterns (Fleiss' generalized kappa 0.62-0.75), and almost perfect reliability for temporal, parietal, and frontal bone (Fleiss' generalized kappa 0.81-0.96). The results demonstrate consistency when three experienced osteopaths evaluate cranial bone mobility restrictions. The results highlight the importance of consensus training and rigorous methodology in manual therapy reliability studies.