There is consensus in favor of a description of the dorsal ligaments of the carpus as not including a direct ligament between the lunate and capitate. On the other hand, there is an anatomical formation which, according to the currently accepted description, corresponds to the dorsal midcarpal capsule, itself thickened by the dorsal intercarpal ligament. The question is whether the capsule at this point deserves to be called an individualizable ligament. In our operative experience of the dorsal carpus, we have encountered a stout structure adherent to the lunate and capitate. In this article, we present the anatomic evidence of this structure\'s existence.
Seven adult fresh frozen upper extremities were dissected. Three wrists were longitudinally sectioned in line with the middle finger metacarpal. The remaining 4 were dissected dorsally. Two representative samples of the stout structure connecting the lunate to the capitate were sent to pathology for histologic analysis and staining.
In all 3 of the longitudinally sectioned wrists, a thick band of tissue could clearly be seen, originating on the lunate, spanning the dorsal interval between the lunate and the capitate, and inserting on the capitate. With this structure intact, dorsal dislocation of the capitate was not possible, but preliminary sectioning of the structure allowed dislocation. In the 4 dorsally dissected wrists, the same connection was observed, palmar to the dorsal intercarpal ligament, in every specimen. The average dimensions of the dorsal capitolunate were: 15.25 ± 1 mm long, 8.75 ± 1 mm wide at the midpoint, and 1.75 ± 1 mm thick. The two specimens sent to pathology after sectioning showed longitudinally oriented collagen fibers. This structure also stained positive for elastin and contained intrasubstance vascular structures.
There is a stout ligamentous structure connecting the lunate to the capitate, palmar to the dorsal intercarpal ligament. Disruption of this structure appears to be necessary for dorsal dislocation of the capitate. Clinical studies are needed to gain better understanding of the exact function and importance of this structure.

Background: Peripheral nerve injuries may affect all age groups and exert devastating impacts on the professional and personal life of the patients. The investigation of nerve regeneration and use of biomaterials and synthetic materials have resulted in advancements in the treatment of peripheral nerve injuries and lesions. Nerve conduits can be used to adjoin the digital sensory nerve spaces of less than 3 cm, especially when the direct tension-free repair of peripheral nerve lesions is not possible. The present study was conducted to evaluate the use of nerve conduits by functional and nonfunctional parameters (i.e. histological study). Methods: This experimental study was conducted on 30 male rabbits. After cutting or crushing the right femoral nerve of the rabbits, they were divided into 3 groups: group 1, with right femoral nerve cut; group 2, with right femoral nerve crushed; and group 3, with right femoral nerve cut using a conduit. The 3 groups were evaluated after 1, 8, and 16 weeks for functional parameters (i.e. walking track analysis). In addition, they were subjected to nonfunctional examination (i.e. histological study) after 16 weeks, then, the results were compared. Results: The 3 groups showed no statistically significant differences in motor recovery in the eighth and 16th weeks (p>0.05). Based on the histological study, group 3 with an end-to-end nerve cutting using a conduit, showed a significantly higher axon count compared to groups 2 and 3 (p<0.05). Conclusion: End-to-end anastomosis using conduit led to axon growth; moreover, comparable functional recovery was observed with end-to-end neurorrhaphy in a rabbit model. Given that the diameter of the nerves and muscles, which might be neurotized in humans, and is much bigger and not comparable to that of the rabbits, it is highly recommended to conduct studies on animals with the larger size, such as primates, to facilitate the generalization of the results to humans.

Scaling and root planing (SRP) is of limited value in many cases, so adjunctive treatment was applied to augment its outcome. Adipose-derived stem/stromal cells (ADSCs) were investigated in periodontal regeneration with promising results. However, they have safety concerns. The exosomes (Exo.), which are extracellular vesicles mediating the action of stem/stromal cells, represent a new approach to overcome these concerns. Ligature-induced periodontitis was induced in 50 rats for 14 days, and they were divided into control (5 healthy rats for histologic comparison), SRP group, ADSCs group, and Exo. group, with evaluation intervals at 2 days, and 2 and 4 weeks, including 5 rats in each interval for each group. The specimens were evaluated for histologic description (H&E), histochemical study (Masson trichrome), and histomorphometric study, to evaluate the area % of newly formed tissues. The Exo. group revealed the best results in all intervals with significantly higher area % of newly formed tissues, followed by ADSCs and, finally, SRP. Both Exo. and ADSCs showed organized newly formed tissues with the Exo. group obtaining comparable histologic results to the normal, healthy tissues by 4 weeks. Adipose-derived stem/stromal cells and their Exo. represent a promising adjunctive treatment to SRP.

A 47-year-old man underwent ceramic cup arthroplasty when he was 22 years old. Revision total hip arthroplasty was performed 25 years later because of limited range of motion without implant loosening. Histologic examination revealed that the femoral head and ceramic implant were well fixed through a thin fibrous membrane. The energy-dispersive X-ray analysis indicated that calcium and phosphorus were detected in the same peak pattern as cancellous bone in the bone-ceramic interface.

This study examined C1 spinal nerve roots and their anastomotic connections with the spinal accessory nerve for histological evidence of sensory neurons in adult humans. C1 spinal nerves and roots with the adjacent segments of the spinal accessory nerve and the spinal cord were dissected en bloc from cadaveric specimens, and prepared for histological study. Results show that in 39.3% of specimens studied, no sensory component to the C1 spinal nerve could be identified. The C1 dorsal root was present 35.7% of the time, and when present it always contained neuronal cell bodies. In the remaining specimens, the sensory contribution to the C1 spinal nerve came through an anastomotic connection with the spinal accessory nerve. The investigators were able to identify clusters of neuronal cell bodies along the spinal accessory nerve at the level of C1 in 100% of the specimens examined.