Experimental investigation of tension-reducing effectiveness of keystone perforator island flap.

Background and aim: Nowadays, the reconstruction of large and complex defects with keystone perforator island flaps (KPIF) has gained popularity in plastic and reconstructive surgery. The keystone perforator island flap was described as a curvilinear shaped trapezoidal design flap, with two V-Y advancement flaps end-to-side. It is a multiperforator advancement flap, based on multiple fasciocutaneous or musculocutaneous perforators, described by Behan in 2003. These flaps have a simple harvest technique, an easy-to-implement design, and they are time and cost-saving. Their blood supply lends a versatile and robust character, with less complications. Nonetheless, their biomechanical properties and effectiveness are unclear, the wound-closure tension-reducing effect is not well documented in existing literature. The present study aims to investigate the wound closure tension-reducing effect of type I, type IIA, type Sidney Melanoma Unit I (SMU) and type SMU II KPIFs. The main purpose of this study was to clarify the tension-reducing effect of the KPIF technique, which can contribute to the understanding of the biomechanical benefits of the KPIF. Methods: This is an experimental, in vivo study, based on twelve white race porcine models (PIC-FII-377), as their anatomy and wound healing process is very similar to that of humans. In this study, 42 wounds that could not be closed by primary wound closure, known as 'unclosable' elliptical defects, were created in six different anatomical regions. The criteria used for not achieving primary wound closure were the breaking of 0 nylon suture or the edges of the wound. Each defect was closed with different types of keystone perforator island flap: type I, type IIA, type Sydney Melanoma Unit I and type Sydney Melanoma Unit II. Keystone perforator island flaps were used in 42 cases. Intraoperative tissue tension was measured by an AXIS FB50, 50 N force gauge tensiometer. In all cases a wide elliptical excision was performed for the primary defect. Before reconstruction, tissue tension was measured across the widest point of the elliptical primary defect. Skin incision was performed for the first flap, without division of deep fascia. After preparing first flap, tension was measured at the widest point of the wound. Furthermore, deep fascia for the second flap was divided, tissue tension across the widest point of the primary defect was measured. Finally, tension was measurement across the widest point of the donor-site after closure of the defect-side flap and V-Y closure of either end of keystone perforator island flap. Results: In this study were included 12 porcine model (PIC-FII-377). A number of 42 keystone perforator island flaps were performed in this study, in six different anatomical regions, ranging between 3.3 x 12 cm and 16 x 30 cm. All elliptical defects were unclosable, with varying sizes ranging between 2 x 4 cm and 8 x 20 cm. The mean tension that was required to close all wounds with primary closure initially was 24.51 N 10.73 N. After using a type I KPIF a tension decrease of -7.04 N ± 4.93 N was seen, in the case of type IIA KPIF the tension decreased to -12.43 N± 5.63 N. Furthermore, after reconstruction with type SMU I KPIF the tension decreased to -7.38N ± 5.21N. After using a type SMU II KPIF a tension decrease of -10.52 N± 5.74 N was seen. Conclusions: The main purpose of this study was to clarify the tension-reducing effect of the KPIF technique, which can contribute to the understanding of the biomechanical benefits of the KPIF. The outcomes of the present study suggest that type I, type IIA, type SMU I, and SMU II of keystone perforator island flaps have a significant tension-reducing effects, especially the technique that involves the division of the deep fascia. The results of this experimental research thoroughly explain the benefits of these flaps. The effectiveness of the flap and doubts on biomechanical properties have not been answered so far. It will encourage more plastic surgeons to use the flap, especially given its proven benefits.

Surgical management of hidradenitis suppurativa with keystone perforator island flap.

INTRODUCTION: Hidradenitis suppurativa is a chronic, relapsing disease of the skin, characterized by apocrine gland and pilosebaceous complex infections, causing recurrent superficial nodules and abscesses, fistula formation, scarring and fibrosis. It is accepted that wide local excision and local coverage is the crucial treatment to prevent recurrence of the disease. MATERIALS AND METHODS: All patients presenting for surgical treatment of hidradenitis suppurativa between 2014 and 2019 were identified from the hospital database. Only patients with hidradenitis suppurativa confined to the axillary, inguinal or sacrococcygeal regions in Hurley grade II and III were included. A total of 21 patients (11 male, 10 female) aged between 21 and 76 years were evaluated retrospectively. All of the 22 defects were reconstructed with keystone perforator island flap following wide local excision. We performed descriptive analysis of demographic data, comorbidities, topographic distribution of lesions, Hurley scoring, size of defect, specific type of reconstruction, complications, follow-up period, recurrences. RESULTS: 21 patients with localized axillary, inguinal or sacrococcygeal hidradenitis suppurativa were identified, and 22 keystone perforator island flaps were performed. All keystone perforator island flaps survived giving a durable cover to the affected regions. There were no complications. Functional and aesthetic results were satisfactory and there were no recurrences. CONCLUSION: These findings confirm that the keystone perforator island flap procedure can be effective for immediate defect reconstruction after wide local excision of advanced hidradenitis suppurativa of the axillary, inguinal and sacrococcygeal regions and provides excellent aesthetic results.

High Division of the Median Nerve with Unusually High Origin of the 3rd Space Common Digital Nerve.

BACKGROUND: Median nerve (MN) variation in the carpal tunnel has been well documented by Lanz. Encountering rarely documented variants, that do not fit into existing classifications, increases the risk of iatrogenic injury. METHODS: The random occurrence of two unclassifiable anatomical variants of the MN in the carpal tunnel gives motivation to search the literature for similar and identical cases. CASE REPORTS: This article presents two cases of very rare anatomical variants of high division of the MN. First case is a pure high branching of the 3rd space common digital nerve (CDN). The second case is a high division of the MN to a thicker lateral component and a thinner medial component. The lateral component of the MN gives off the palmar cutaneous branch (PCB), the thenar motor branch (TMB), the 1st and 2nd space CDN's and contributes medially with a branch to the 3rd space CDN. The medial component of the MN bifurcates distally into a medial and lateral branch. The lateral branch from the medial component of the MN distally unites with the medial branch of the lateral component of the MN to form the 3rd space CDN. The medial branch from the medial component of the MN has a major contribution to the 4th space CDN from the ulnar nerve. In both cases, the medial component of the MN has a transmuscular course through the flexor digitorum superficialis (FDS) muscle. DISCUSSION: Finding similar case reports from worldwide suggests the need to improve current classification of the MN variants in the carpal tunnel. CONCLUSIONS: One cannot rely entirely on the existing anatomical classifications of the MN in the carpal tunnel. There is an underappreciated risk of iatrogenic injury, especially in endoscopic carpal tunnel release, and a chance of missing out on repair of important anatomical structures in trauma cases. There is a possibility of augmenting group 3 of Lanz's classification by adding subgroup "3D High division of the MN with the medial component having a transmuscular course through the FDS muscle", stating the different distal branching patterns.