Purpose Adjacent segment degeneration (ASD) is one of the major complications of lumbar fusion. Several previous retrospective studies reported ASD after PLIF. However, few reports evaluated whether decompression surgery combined with fusion surgery increases the rate of complications in adjacent segments. The purpose of the current study was to investigate the degeneration in decompressed adjacent segments after PLIF. Methods A total of 23 patients (12 men, 11 women; average age, 58.6) who underwent PLIF surgery [1 level (n = 9), 2 levels (n = 8), 3 levels (n = 4), 4 levels (n = 2)] were included. Additional adjacent decompression above or below the level of interbody fusion was performed at 25 levels and no adjacent decompression was performed at 15 levels. We retrospectively investigated ASD by X-ray films of all 40 adjacent segments (above and below fusion level) and clinical outcomes of all 23 cases.Results Of the 40 adjacent segments, 19 (47.5 %) showed ASD and 9 (22.5 %) showed symptomatic ASD. In the 19 segments with ASD, ASD occurred in 16 of 25 (64.0 %) segments at decompressed sites compared with 3 of 15 (20.0 %) non-decompressed sites. The ratio of ASD in adjacent segments was significantly higher at decompressed sites than at non-decompressed sites (p \ 0.01). Conclusion ASD occurs frequently in association with additional decompression above or below the level of PLIF. In cases in which the adjacent segments require decompression, a surgical strategy that preserves as much of the posterior complex as possible should be selected.

ABSTRACT:The study is concerned with the quantitative measurement of changes in friction, surface roughness, and tensile strength during the compaction of Ficus deltoidea powder, a well-known Malaysian herb. In the compaction process, the force applied for compaction (upper punch) was greatly influenced by the friction between die wall and powder bed during transmission to the lower punch. Wall friction was found to increase with the increasing load and weight of powder due to an increase in surface contact with the die wall. The coefficients of wall friction decreased from 0.47 to 0.36 for increasing weight of powder from 0.8-1.5 g. Tablets with a higher compaction load of 9.5 kN had a lower arithmetic mean deviation (Ra), an indicator of surface roughness. Ra for the top surface is lower than that of for the bottom surface.