Disproportionate Vertebral Bodies and Their Impact on Lumbar Disc Herniation.

BACKGROUND: The aim of this study was to determine whether the presence of disproportionate vertebral bodies is a risk factor for disc herniation (DH). METHODS: Sixty-seven consecutive patients (m: 31 f: 36) who underwent lumbar discectomy for symptomatic DH at one level between L3 and S1 were retrospectively included. The last three motion segments (3 × 67 = 201) were assessed on sagittal MRI scans. A disproportionate motion segment was defined as the difference of more than 10% of the antero-posterior diameter of two adjacent endplates. RESULTS: DH was present in 6/67 (9%), 26/67 (38.8%), and 35/67 (52.2%) patients at L3/4, L4/5, and L5/S1, respectively. A total of 14 of 67 patients demonstrated a disproportionate motion segment at the discectomy level (20.9%). A total of 23 of the 201 (11.4%) investigated motion segments met our criteria for a disproportionate motion segment. In our study population, when one of the 201 segments was disproportionate, the positive predictive value (PPV) for DH increased toward the lower segments: the PPV at the L5/S1 level was 83.0%. The odds ratio of disproportion for DH was the highest at the L5/S1 level, with 6.0 ± 0.82 (p = 0.017). CONCLUSIONS: The presence of a disproportionate motion segment in the lower spine may lead to a significant higher risk for DH in patients undergoing discectomy.

Degeneration of the atlanto-axial joints: a histological study of 9 cases.

Degeneration of the lateral atlanto-axial joints (AAJ) has been described as a potential cause of severe neck pain. However, hardly any data are available on its incidence, especially in comparison to the lower cervical spine. In this histological study, we examined the AAJs in 9 specimens from elderly patients, graded the findings and compared them to those in the facet joints of the lower cervical spine. Most histological changes in the AAJs were mild, but the changes in the lower cervical spine were severer. Previous mechanical studies have described the AAJ as a very mobile joint with large neutral zones, which may explain the mild degree of osteoarthrosis found in these specimens.