| Effects of Lateral Cranial Translation on the Appearance of the Atlanto-Occipital Joint Patricia Kuhta, BS, DC
ABSTRACT
Over the past seventy years there has been considerable research done and literature written on the subject of cervical biomechanics. The researchers on this topic have been from the medical and chiropractic professions alike. These researchers include such names as White and Panjabi, Kapandji, Dr. Don Harrison, Dr. John F. Grostic, and Dr. A.A. Wernsing to name a few. Each researcher has studied and documented a slightly different aspect or a specific portion of information concerning cervical biomechanics. Some studied cadaveric specimens, determined ranges of motion at the upper cervical joints, discovered information about the biomechanics of the occiput and atlas during lateral flexion of the neck, and so on. However, despite this research there is a lack of information available on how the atlanto-occipital joint is affected by lateral translation of the head.
Interest in this topic developed over a period of several years in the X-ray department of Sherman College because of a peculiar pattern occurring on patients' APOM and Nasium films. Patients frequently appeared on film to have a list, lean or lateral translation of the head on the cervical spine. Due to the lack of research on the topic of lateral cranial translation it is currently unknown what effect this type of translation has on the appearance of the atlanto-occipital joint. This lack of information is troubling considering the emphasis and importance placed on the atlas vertebra and its proper alignment in subluxation correction.
Objective
The purpose of this study is to investigate the normal biomechanics of lateral translation of the skull and cervical spine and the effect it has on the appearance of atlas laterality on the Anterior-to-Posterior Open Mouth (APOM) x-ray. The presence of lateral translation of the head is expected to affect the positional relationship between the occipital condyles and atlas lateral masses. This will therefore influence the appearance of atlas laterality on the APOM x-ray.
Research Design and Methods
Forty-nine subjects were chosen from Sherman College Health Center's new patient base. A six view cervical x-ray series was taken of each subject, consisting of a nasium, base posterior, neutral lateral, neutral APOM, APOM with right lateral translation, and APOM with left lateral translation. The neutral APOM and translation APOM views were taken with extra care to make sure that head rotation and tilt are removed. For all three APOM views, the central ray was centered on C1 in the vertical center of the subject's mouth.
Analysis of Films
The subject's atlanto-occipital positional relationship on the translation APOM views was compared to that of the neutral APOM using the standard laterality methods taught in the Sherman curriculum. Three examiners, blinded to the patients' head position and to each other evaluated the atlas laterality. Hence inter-examiner reliability of the analysis method can be assessed.
Results will be presented at the 2003 Verterbral Subluxation Conference.
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