Steven P. Haman

Effect of the increase in the height of lumbar disc space on facet joint articulation area in sagittal plane.

Study Design. Computerized tomography (CT) of the lumbar spine cadaveric specimens was used to evaluate the effect of increasing the height of the disc space in the lumbar spine to the facet joint articulation in the sagittal plane. Objective. To show how the facet joint articulation is affected by increasing the height of the disc space in the lumbar spine. Summary of Background Data. The Charité Artificial Disc (DePuy Spine, Inc., Raynham, MA) was successful in relieving low back pain in the majority of patients, yet there was still a significant number of patients who did not obtain pain relief, or their pain even worsened. The etiology of their pain is still not known. To our knowledge, no study has addressed the effect on the facet joints when the disc height is increased. Methods. CT images passing through the center of the L3–S1 facet joints (sagittal plane) were obtained from 15 cadaveric lumbar spine specimens. The articulation overlap of facet joints in sagittal plane from the L3 to S1 was measured. A 1-mm incremental increase to a total 5 mm in disc space height was performed to simulate the changes seen in disc replacement. The change in the facet joint articulation overlap in sagittal plane at normal and each displacement was then measured. There were 5 lumbar spine specimens dissected to validate the technique and standardize the measurements. Mean, percentages, and standard deviation values were calculated for all measured dimensions. Results. No significant difference was found between the measurements on CT and gross specimens (P > 0.05). In 15 specimens, the mean facet joint articulation overlap on the sagittal plane was: 16.29 ± 1.20 mm (left) and 16.22 ± 1.16 (right) at the L3–L4 level; 17.81 ± 1.18 mm (left) and 17.74 ± 1.18 mm (right) at the L4–L5 level; and 18.18 ± 1.18 mm (left) and 18.23 ± 1.15 mm (right) at the L5–S1 level. There is no significant difference between the measured values on left and right sides (P > 0.05). Each 1-mm incremental increase in disc space at the L3–L4 level translated to a decrease in the facet joint articulation overlap in the sagittal plane by 6%, and the mean facet joint space increased 0.4 mm. At the L4–L5 level, the articulation overlap decreased by 6%, and the facet joint space increased 0.5 mm. At the L5–S1 level, the articulation overlap decreased by 4%, and the facet joint space increased 0.7 mm. Conclusions. There is a significant decrease of the facet joint articulation overlap in sagittal plane and an increase in the facet joint space following an increase in the lumbar disc space. The inappropriate increase of the height of disc space will result in facet joint subluxation.

Open Reduction and Internal Fixation of 117 Tibial Plateau Fractures

This retrospective study evaluated the surgical management of 117 tibial plateau fractures treated between 1990 and 1998. At last patient follow-up, results were rated good to excellent in 94, fair in 13, and poor in 10 cases. Follow-up radiographs showed degenerative changes in the lateral compartment in 29 cases. Other complications included five wound infections, two deep venous thromboses, five delayed unions, and three nonunions. Operative treatment of tibial plateau fractures is recommended as it enables better alignment, meniscal access, and other soft-tissue injury repair.

How the increase of the cervical disc space height affects the facet joint: an anatomy study.

Study Design. In vitro study on the effect of increasing the height of the cervical disc space on the facet joint. Objectives. To demonstrate how facet joint articulation is affected by increasing the cervical disc space height. Summary of Background Data. A surgeon attempts to increase the disc space and inserts a larger artificial disc than normal in order to keep the intervertebral foramen open and the prosthesis stable. However, it is hypothesized by the current authors that this procedure could have an adverse effect on the facet joints. Methods. Computerized tomography images passing through the disc space and the center of the C4–C7 facet joints (sagittal plane) were obtained from 15 cadaveric cervical spine specimens. A 1-mm incremental increase to a total 5 mm in disc space height was performed to simulate the changes seen in disc replacement. The change in the facet joint articulation overlap and space in the sagittal plane at normal and each displacement was measured. Results. Each 1-mm incremental increase in disc space at C4–C5 translated to a decrease in the facet joint articulation overlap in the sagittal plane by approximately 8%. The mean facet joint space increased approximately 0.8 mm. At the C5–C6 and the C6–C7 levels, the articulation overlap decreased by approximately 7% and the facet joint space increased approximately 0.8 mm. Conclusions. There is a significant decrease of the facet joint articulation overlap in the sagittal plane and an increase in the facet joint space following an increase in the cervical disc space. The inappropriate increase of the disc space height may result in facet joint subluxation and could lead to the accelerated failure of the artificial disc.