Histological investigation of common insensate flaps obtained from the hand and forearm regions for use in fingertip reconstruction

Application of extended ulnar parametacarpal perforator free flap for the reconstruction of total pulp defect of the thumb: A case report

Many procedures are available for the coverage of thumb pulp defects; however, to gain thumb function and esthetics, a similar tissue is desirable. If the length of the longitudinal defect is <2 cm, a volar advancement flap is appropriate; however, if the flap is >2 cm long or wider, retrograde or free flaps are required. Here, we present a case of thumb pulp reconstruction using an extended ulnar parametacarpal perforator (UPM) flap, which achieved excellent functional and esthetic outcomes. A 46-year-old man underwent reconstruction surgery of his thumb, which was a degloved total pulp. A sensate 5.2 × 3.2 cm UPM flap was designed on the ulnar side of the right palm and transferred to his thumb. The flap donor site was covered with a V-Y advancement flap on the dorsal side of the right hand. At 12 months postoperatively, the patient achieved a functional and natural thumb appearance with high satisfaction. The UPM flap can offer soft tissue similar to the pulp region in the digit without a palm scar at the donor site. This extended application is suitable for the reconstruction of a total pulp defect of the digit and is an alternative option for a hemi-pulp flap from the toe area.

Reconstructive Timing of Nail Preserved Fingertip Injury With Reverse Digital Artery Island Flap

BACKGROUND

This study aimed to compare the outcomes of reverse digital artery island flap (RDAIF) in primary and secondary reconstruction after failed replantation or composite graft method.

METHODS

This study retrospectively analyzed 42 patients that underwent RDAIF (18 primary and 24 secondary). Preoperative details (demographics, injury details, and waiting days) and postoperative outcomes (active arc of proximal interphalangeal [PIP] and distal interphalangeal (DIP) joints, extension loss of PIP, flexion arc of metacarpophalangeal joint, total active motion, flap sensation, the presence of numbness, Tinel's sign and cold intolerance) were evaluated. Quick Disabilities of the Arm, Shoulder, and Hand score (Quick-DASH) and patient satisfaction were also statistically compared between the 2 groups.

RESULTS

There was no significant difference in patient demographics between the 2 groups in sex, age, smoking and diabetic history, affected hand and finger, injury type and level, and flap area. The only difference was in waiting days. Similar sensory recovery and patient satisfaction were found in both groups. Range of motion in the DIP and PIP joints, extension loss of PIP, total active motion, and Quick-DASH were superior in the primary coverage group. Increasing age, subzone III injury, and secondary reconstruction were found to be the factors that adversely affected the postoperative range of motion.

CONCLUSIONS

Secondary reconstruction was more likely to result in joint contracture. In the event of a damaged fingertip amputation in older patients, primary flap reconstruction should be considered as the initial treatment of choice, with regard to the ultimate range of motion.

Epigenetic regulation and signalling pathways in Merkel cell development

Merkel cells are specialized epithelial cells connected to afferent nerve endings responsible for light-touch sensations, formed at specific locations in touch-sensitive regions of the mammalian skin. Although Merkel cells are descendants of the epidermal lineage, little is known about the mechanisms responsible for the development of these unique mechanosensory cells. Recent studies have highlighted that the Polycomb group (PcG) of proteins play a significant role in spatiotemporal regulation of Merkel cell formation. In addition, several of the major signalling pathways involved in skin development have been shown to regulate Merkel cell development as well. Here, we summarize the current understandings of the role of developmental regulators in Merkel cell formation, including the interplay between the epigenetic machinery and key signalling pathways, and the lineage-specific transcription factors involved in the regulation of Merkel cell development.

Investigations on T cell transmigration in a human skin-on-chip (SoC) model

A microfluidics-based three-dimensional skin-on-chip (SoC) model is developed in this study to enable quantitative studies of transendothelial and transepithelial migration of human T lymphocytes in mimicked skin inflammatory microenvironments and to test new drug candidates. The keys results include 1) CCL20-dependent T cell transmigration is significantly inhibited by an engineered CCL20 locked dimer (CCL20LD), supporting the potential immunotherapeutic use of CCL20LD for treating skin diseases such as psoriasis; 2) transepithelial migration of T cells in response to a CXCL12 gradient mimicking T cell egress from the skin is significantly reduced by a sphingosine-1-phosphate (S1P) background, suggesting the role of S1P for T cell retention in inflamed skin tissues; and 3) T cell transmigration is induced by inflammatory cytokine stimulated epithelial cells in the SoC model. Collectively, the developed SoC model recreates a dynamic multi-cellular micro-environment that enables quantitative studies of T cell transmigration at a single cell level in response to physiological cutaneous inflammatory mediators and potential drugs.

Evaluation of Neurotized Hypothenar Free Perforator Flaps Used for Fingertip Reconstruction

INTRODUCTION

In reconstruction of digital amputations of the upper extremity, composite tissue alternatives with similar features are limited for finger tip reconstruction. Among these alternatives, free perforator flaps elevated from the hypothenar region (HFPFs) are defined, but reluctancy goes on for utilization of these flaps.In this study, we aimed to highlight the sensory results of HFPFs when a neural repair is incorporated to the flap and also to justify their usage by presenting functional and aesthetic outcomes of the reconstructions performed with HFPFs.

METHODS

This clinical study was conducted from June 2015 to June 2017. Twelve patients with acute finger tip amputations were examined. Distal amputation levels were subgrouped according to Ishikawa classification. Patient demographics and amputation etiology were listed. All fingertip defects were reconstructed with a neurotized HFPF. All perforator anastomoses were performed in an end-to-end fashion. During follow-up, 2-point discrimination and dynamometric test were conducted. In addition, the Michigan Hand Outcomes Questionnaire was carried out. Evaluation of the results from a cosmetic standpoint was also conducted, with 4 blinded, independent surgeons using the visual analog scale.

RESULTS

Of 12 digital amputations reconstructed with neurotized HFPFs, 10 were totally viable during follow-up, whereas partial loss was observed in 2 flaps. The mean age was 38.8 ± 11.8 years. Most of the amputations were classified as Ishikawa subgroup 2 (50%). The mean dynamic 2-point discrimination was 3.2 ± 0.11 mm and slightly greater compared with contralateral digit (P = 0.003). Also minor decreases were measured in forced grip and pulp-to-pulp grip strengths (P = 0.003). Overall satisfaction was 92.7% in Michigan Hand Outcomes Questionnaire. Average visual analog scale score was 7.25 out of 10.

CONCLUSIONS

Hypothenar free perforator flaps, with incorporation of neural repair, give promising results for reconstruction of the fingertip. In addition to superior sensorial outcomes, HFPFs yield satisfying results from aesthetic and functional perspectives.

Use of a vascularized dorsal sensory branch of an ulnar nerve flap for repairing a proper digital nerve with coverage of a volar soft tissue defect: Report of two cases

To repair a short nerve gap, autograft, allograft, autogenous, or synthetic conduits are selected, but a vascularized nerve autograft is preferred to obtain a reliable postoperative outcome in the case of an unfavorable wound bed. The purpose of this report is to describe and evaluate two cases of repair of a proper digital nerve and volar soft tissue defect with a vascularized dorsal sensory branch of an ulnar nerve flap. The cases of two men, 40 and 20 years old, who suffered index finger defects due to crush lacerations that required a flap and a nerve graft, are presented. A 4.0 cm × 2.0 cm and a 3.2 cm × 1.6 cm flap, which were nourished by the perforators from the ulnar proper digital artery of the little finger, were elevated from the ulnar side of fifth metacarpal bone head and transferred for coverage of the soft tissue defect. A 4.6-cm and a 3.0-cm vascularized nerve graft was interposed in the nerve gap. The patients' postoperative courses were uneventful, and both patients had no complaints related to the donor site. Static and moving two-point discrimination were 8 and 6 mm, respectively, at 6 months after surgery in the first case and 5 and 3 mm, respectively, at 9 months after surgery in the second case. This flap, which could be elevated in the same operative field with a nerve having similar diameter to that of the proper digital nerve, was useful for repair of a finger volar tissue defect.

Reference values for skin microanatomy: A systematic review and meta-analysis of ex vivo studies

BACKGROUND

Few studies have characterized reference values of normal human skin microanatomy parameters.

OBJECTIVE

To quantify histologic measurements of epidermal thickness, melanocyte density, hair follicle density, and eccrine gland density as a function of age and anatomic site.

METHOD

We searched the PubMed, Embase, Web of Science, and Cochrane databases for articles published through May 25, 2017. Two reviewers independently screened 2016 articles; 327 relevant articles and 151 additional articles found via forward or reference citations underwent full-text review by 1 of 4 reviewers for relevance, data extraction, and critical appraisal. Weighted averages, meta-analysis, and meta-regression were used in statistical analysis.

RESULTS

A total of 56 articles were included; when all anatomic locations were used, the overall estimates for epidermal thickness, melanocyte density, hair follicle density, and eccrine gland density were 99.75 μm (95% confidence interval [CI], 83.25-116.25), 955.05 cells/mm² (95% CI. 880.89-1029.21), 1.40 hairs/mm² (95% CI. 0.91-1.89), and 1.28 glands/mm² (95% CI. 0.91-1.64), respectively.

LIMITATIONS

There was significant data heterogeneity across studies, possibly because of differences in histological techniques and absence of standardized microanatomy definitions.

CONCLUSIONS

We established summary estimates for normal human skin microanatomy parameters.