Morphological characteristics of the Lisfranc ligament

BACKGROUND

This study aimed to clarify the morphological characteristics of the Lisfranc ligament and the cuneiform 1-metatarsal 2&3 plantar ligament (CMPL).

METHODS

Forty legs from 20 cadavers were examined. Classification proceeded according to the number of fiber bundles in the Lisfranc ligament and the CMPL. Morphological features measured were fiber bundle length, width, thickness, and angle.

RESULTS

In Type I-a, the Lisfranc ligament and the CMPL were a single fiber bundle; in Type I-b, the Lisfranc ligament was a single fiber bundle, and the CMPL was two fiber bundles; in Type II-a, the Lisfranc ligament was a two fiber bundle, and the CMPL was a single fiber bundle; in Type II-b, the Lisfranc ligament and the CMPL were two fiber bundles; in Type III-a, the Lisfranc ligament was three fiber bundles, and the CMPL was a single fiber bundle; in Type III-b, the Lisfranc ligament was three fiber bundles, and the CMPL was two fiber bundles; in Type IV, the Lisfranc ligament and the CMPL could not be separated. Type I-a was seen in 37.5%, Type I-b in 10%, Type II-a in 30%, Type II-b in 7.5%, Type III-a in 7.5%, Type III-b in 2.5%, and Type IV in 5%. The Lisfranc ligament was significantly larger than the CMPL in total fiber bundle width, total fiber bundle thickness, and total fiber bundle angle.

CONCLUSION

The Lisfranc ligament had up to 3 fiber bundles and the CMPL had one or two fiber bundles; classifications were four types and two subgroups.

Morphological features of the cervical ligament

PURPOSE

The purpose of this study was to clarify the morphological characteristics of the cervical ligament (CL).

METHODS

This study examined 80 legs from 40 Japanese cadavers. The CL was classified by the number of fiber bundles. The morphological features measured were fiber bundle length, width, thickness, and angle with the sagittal plane.

RESULTS

The CL was classified as follows: Type I, the CL is a single fiber; Type II, the CL consists of a superficial fiber and an inferior fiber; and Type III, the CL consists of a superficial fiber, intermediate fiber, and inferior fiber. Type I was seen in 15 feet, Type II in 57 feet, and Type III in 8 feet. In comparisons of morphological features within each type, significant differences were seen in fiber bundle length, width, and angle between superior fiber bundles and inferior fiber bundles of Type II and Type III. In comparison among types, the total fiber bundle width was significantly wider in Type II and Type III than in Type I, and the angle was significantly smaller in Type III than in Type I.

CONCLUSION

The results of this study suggested that each type may have different sub-talar joint control functions.

Morphological features of the posterior intermalleolar ligament

PURPOSE

In the present study, the posterior intermalleolar ligament (PIML) was classified by type using large-scale cadavers to provide basic information to help elucidate the mechanism of ankle joint posterior impingement syndrome.

METHODS

This investigation examined 100 legs from 49 Japanese cadavers (mean age at death, 79 ± 11 years; 58 sides from men, 42 from women). In the classification method, an absent PIML was classified as Type I, a PIML with one fiber bundle (attachment to one place) was Type II, a PIML with two fiber bundles (attachment to two places) was Type III, and a PIML with three fiber bundles (attachment to three or more places) was Type IV. Furthermore, according to other adhering tissues, they were further subdivided and classified by type.

RESULTS

There were various types of PIML: 19 (19%) Type I; 24 (24%) Type II; 23 (23%) Type III; and 34 (34%) Type IV. A PIML was present in 81 legs (81%). There were no significant differences between men and women and between left and right sides.

CONCLUSIONS

The complex relationships of the PIML with the surrounding ligaments and tissues are considered to be among the factors that make interpretation of imaging findings difficult.

Lewis acid-catalyzed ring-opening reactions of semicyclic N,O-acetals possessing an exocyclic nitrogen atom: mechanistic aspect and application to piperidine alkaloid synthesis

Ring-opening reactions of semicyclic N,O-acetals possessing an exocyclic nitrogen atom with silicon-based nucleophiles (silyl enol ethers, ketene silyl acetals, allylic silanes, and trimethylsilyl cyanide) were systematically studied for the first time. It was found that the reactions were effectively catalyzed by a Lewis acid, trimethylsilyl trifluoromethanesulfonate (TMSOTf), to afford 1,4- and 1,5-amino alcohols in high yields. In reactions of 3-oxygen functionalized semicyclic N,O-acetals, high 1,2-syn-diastereoselectivity was obtained. By 1H NMR experiment, the formation of the O-trimethylsilylated ring-opened product was observed as the initial product. Furthermore, the epimerization between the diastereomers of a 3-benzyloxy semicyclic N,O-acetal suggested the transient formation of an acyclic iminium ion species as a reactive intermediate. It was also found that 3-acetoxy and 3-benzyloxy N,O-acetals showed a tendency for the larger nucleophile to provide higher syn-selectivity, while 3-tert-butyldiphenylsilyloxy N,O-acetals showed the opposite tendency. These stereochemical outcomes can be rationalized by assuming four transition state models for the acyclic iminium ion intermediate. The synthetic utility of the reaction has been demonstrated in the diastereoselective synthesis of piperidine alkaloids, (+)-isofebrifugine and (+/-)-sedacryptine.

Highly stereoselective synthesis of homoallylic amines based on addition of allyltrichlorosilanes to benzoylhydrazones

Allyltrichlorosilanes reacted with benzoylhydrazones in DMF without the use of any catalyst to afford the corresponding homoallylic benzoylhydrazines in good to high yields. The reactions proceeded at 0 degrees C to room temperature under mild conditions. In addition, it was found that the reactions tolerated well the steric hindrance of hydrazones and allyltrichlorosilanes. Indeed, ketone-derived benzoylhydrazones reacted with allyltrichlorosilane smoothly to afford the corresponding N'-tert-alkyl-N-benzoylhydrazines in high yields. In crotylation with (E)- and (Z)-crotyltrichlorosilanes, syn- and anti-adducts were stereospecifically obtained, respectively. These reactions are most likely to proceed via a cyclic chairlike transition state where the R group takes an axial position. When alpha-heteroatom-substituted chiral benzoylhydrazones were used, high anti-diastereoselectivities were observed. These adducts can be readily converted to homoallylic amines in high yields without epimerization.