A systematic review of the keystone design perforator island flap in lower extremity defects

The Keystone Flap: A Game Changer That Promises New Horizons in Reconstructive Surgery

BACKGROUND

Since its first description emerged in 2003, the keystone flap has garnered the attention of the international scientific community due to its high safety profile and the suitably low complication rate associated with the reconstructive process.

MATERIALS AND METHODS

In this study, data were obtained from the performance of 72 keystone flaps to cover soft-tissue defects after the excision of neoplastic processes, excisions, and injuries occurring in polytrauma. The study was conducted in the Department of Plastic Surgery, "Bagdasar-Arseni" Emergency Hospital, Bucharest, and two plastic surgeons in the department performed the surgical procedures.

RESULTS

The statistical analysis revealed a remarkably low complication rate (3.22%), excellent functional and esthetic results, and a short hospitalization time. No intraoperative complications were identified during this study. The degree of satisfaction obtained after reconstructive surgery was exceptionally high, with a score of 9.47 on a 10-point rating scale (0 = poor results, 10 = excellent results) from the patient's perspective and 9.51 out of 10 for the surgical team.

CONCLUSIONS

The keystone flap is the optimal solution for reconstructing soft-tissue defects of variable sizes and shapes. It is associated with a low length of hospitalization, a low complication rate, and high patient satisfaction.

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.

Keystone Flap for Closure of Skin Cancer Defects on the Upper Extremity

Background: We sought to examine the efficacy of the Keystone Design Perforator Island Flap (KDPIF) for the reconstruction of skin cancer excision defects isolated to the upper extremity. In particular, to examine the size of defects repaired and the complications associated with the keystone flap procedure isolated to the upper extremity. Methods: This is a retrospective chart review including all patients older than 18 years of age who received a KDPIF procedure between February 2013 and February 2019 for the oncologic reconstruction of skin cancer defects isolated to the upper extremities by a single surgeon. All procedures were done according to the original description by Behan. Results: A total of 32 patients, 18 (56%) male and 14 (44%) female, received 35 keystone flaps between February 2013 and February 2019. The mean age of the males and females was 70.5 and 79.7 years of age, respectively. Thirty-five lesions suspicious for cancer were excised and 14 (40%) basal cell carcinoma (BCC), 11 (31%) squamous cell carcinoma (SCC), 9 (26%) melanoma, and 1 (3%) actinic keratoses diagnoses were histopathologically determined. Skin defect excisions varied from 3.53 cm2 to 31.42 cm2. No intraoperative or postoperative complications occurred. Conclusions: The keystone flap is a successful versatile flap procedure with a low or absent complication rate for the reconstruction of skin cancer excision defects of various locations (eg arm, hand, elbow, forearm, shoulder, and wrist), cancer pathologies, and sizes on the upper extremity. When needed, a Doppler may successfully identify adequate perforating blood vessels for the relatively larger flaps.

A bipedicled keystone perforator island flap: Pedicle division technique with enhanced advancement potential for chronic wound coverage

Since the first description of the keystone perforator island flap (KPIF) in 2003, several modifications have been suggested to enhance its coverage ability. However, locoregional flaps have limited its use in chronic wounds due to decreased elasticity around the defect. We investigated the use of a bipedicled KPIF (bKPIF), which covers a defect while completely elevating the median part of the flap from the fascia. A retrospective chart review of 20 consecutive patients who underwent classical type I KPIF (n = 10) or bKPIF (n = 10) reconstruction from June 2020 to December 2022 was performed. Baseline characteristics, indications, operative details, healing time, and complications were analyzed and compared between the two groups. The average defect size was 30 cm2 in type I KPIF and 36.6 cm2 in bKPIF, and an average flap size of 86.5 cm2 was covered in type I KPIF, larger than bKPIF at 73.8 cm2. The flap/defect ratio was significantly lower in the bKPIF group (p < 0.02), with an average of only 55% pedicular area. The average advancement distance in the bKPIF group was 1.85 cm (standard deviation 0.78) greater than that in the type 1 KPIF group. There was no significant difference between the groups in terms of operation time, complete healing time, and complications. All ten bKPIFs were successful without any flap necrosis. Even though the mean pedicular area in the bKPIF group was nearly half compared with that in the type I KPIF group, it was sufficient to perfuse the entire flap without any major complications. This novel technique using bKPIF has potential clinical relevance, as evidenced by the enhanced ability to cover chronic defects with severe scarring. Lateralizing the hotspots to the bilateral corners of the flap is the mechanism that facilitates this potential.

How to Transform a Perforator Propeller Flap into a Keystone Flap in Case of Unsatisfying Perforator Vessel Local Perforator Flap Coverage in Limbs

Moderate soft-tissue defects need stable coverage, ideally with tissue of similar characteristics and low donor site morbidity. We propose a simple technique for the coverage of moderate skin defects in the limbs. It allows intraoperative transformation of a propeller perforator flap (PPF) into a keystone design perforator flap (KDPF) in cases of unsatisfying perforator vessel or in cases of unpredictable intraoperative events. Between March 2013 and July 2019, nine patients with moderate soft-tissue defects (mean defect size 4.5 × 7.6 cm) in the limbs (two on the upper limbs and seven on the lower limbs) were covered using this technique. We performed four PPFs and five KDPFs. The mean follow-up was 5 months. There was one complication, partial distal tip necrosis in a PPF located in the leg, which healed by secondary intention within 3 weeks. The donor site was closed directly in all cases. No functional impairments were noted regardless of the perforator flap utilized. This technique enables us to employ flexible surgical strategies and allows us to make adjustments based on the patient's vascular anatomy.

Customized reconstruction with rotation Hemi-Keystone flap

INTRODUCTION

The keystone perforator flap has become a versatile alternative for reconstruction of cutaneous defects of various etiologies and in all age groups. However, it demands a notable incision area proportional to defect size and is more prone to excessive tension during defect closure. We present a novel modified rotation Hemi-keystone flap that reveals its excellence in flap survival.

METHODS

Between March and December 2021, a retrospective chart review was conducted of 40 patients who received rotation Hemi-keystone flap for coverage of cutaneous defects by a single surgeon. The primary outcome was successful flap survival.

RESULTS

We performed a total of 45 modified rotation Hemi-keystone flaps for reconstruction of cutaneous wound defects. The location of the wound defects was in the head and neck (38%), extremities (35.7%), and trunk (26.2%). The most common cause of wound defect is tumor resection (45.2%). The mean wound defect dimensions were 3.5 cm × 3 cm. The mean follow-up time was 6 months. There were no significant complications, with only one patient (2.4%) having minor wound dehiscence, which was treated by local wound care.

CONCLUSIONS

The current series presents a simple, reliable, and versatile modification of the traditional keystone flap that minimizes morbidity at the reconstruction site along with improvement of flap mobility for successful reconstruction of cutaneous defects in a tension-free manner. The favorable outcome of this technique contributes to the inclusion of the rotation Hemi-keystone flap as an excellent surgical option in the reconstruction of various soft tissue defects.

The UQ Flap: A Novel Modification of the Keystone Flap

Wound closure following excisions on the leg (between the knee and ankle), including the distal leg, is challenged by limited skin laxity. The keystone flap, first described by Behan in 2003, was proposed as one solution, but with a significant complication rate on the distal leg. This pilot study introduces a novel modification of the keystone flap, named the UQ flap, differing from other modifications, with an un-incised portion on one flap border and a unique curved leading-edge to absorb tension and distribute shearing forces in different directions, providing improved flap security and vascularization. The UQ flap was performed on 10 patients in two formats of "U" and "Q" also with two different orientations as base-proximal and base-distal. Other variations including minor deviation from the longitudinal axis, and double flap, were also performed. Except for one case with minor infection, there were no complications, and the results were favorable. No fasciotomy or undermining was required. The UQ flap proved to be a safe and convenient method of wound closure on the leg, including the distal leg. Compared with the keystone flap, there were reduced incisions leading to improved vascularity and less healthy tissue trimming. Its unique shape provided flap flexibility facilitating easy adjustment to the defects. The order and direction of wound closure after the excision of the lesion and incision of the flap are critical.

Comparison of the Keystone flap and the Limberg flap technique in the surgical treatment of pilonidal sinus disease

Pilonidal sinus (PS) disease is a chronic inflammatory disease of the sacrococcygeal region. Although various methods have been described for surgical treatment, there is no consensus on the best surgical technique. The aim of this study was to present the results of a new advancement flap technique named the "Keystone flap (KSF)" and compared with the Limberg flap (LF) technique in pilonidal sinus surgery. A retrospective review was made of 124 consecutive patients surgically treated for PS disease with KSF and LF procedures. Baseline characteristics, operation time, volume of excised specimen, duration of hospitalization, duration of drainage, duration of healing, time to return to work, local complications and recurrence were evaluated and compared between the two procedures. Operation time, healing time, and time to return to work were significantly shorter in the KSF group. Partial wound dehiscense and prolonged wound healing were more common in the LF group. An additional intervention in the operating room was required by 21.1% of the LF group and was a significantly lower rate in the KSF group at 7.5%. There was no significant difference between the groups in terms of recurrence. The KSF procedure seems promising for treating pilonidal sinus disease, with the advantages of shorter operation, healing, and return to work times. It also provides lower partial wound dehiscence and necrosis rates.

A systematic review of the keystone design perforator island flap in the reconstruction of trunk defects

The keystone design perforator island flap can be utilized in the repair of trunk defects. A systematic review was carried out to identify the complication rates of the use of this flap to treat such defects. The MEDLINE, Embase, Cochrane Library, and PubMed Central databases were searched for articles published between January 2003 and December 2018 that reported the use of keystone design perforator island flaps in the repair of trunk defects. Study selection was conducted in alignment with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Eight articles involving a total of 54 flaps satisfied the inclusion criteria. The most frequently reported cause of trunk defects was oncologic resection (64.4%). The overall complication rate was 35.2%, and complications included infection (11.1%), wound dehiscence (7.4%), delayed healing (7.4%), and partial flap loss (1.9%). The keystone design perforator island flap is associated with a high success rate and low technical complexity. Despite minor complications, keystone design flaps could be a preferred choice for trunk reconstruction.

Keystone Flaps: Physiology, Types, and Clinical Applications

The keystone perforator flap (KPF) was first introduced in 2003 by Behan et al for use in reconstruction after skin cancer excision. Since its initial description, KPF use has been expanded to complex defects of various etiologies and disorders throughout the body. At its most basic, the KPF is a perforator-type flap designed with a 1:1 flap-to-defect width ratio. Keystone perforator flaps are specifically raised on pedicles arising from musculocutaneous or fasciocutaneous perforator vessels. Major advantages of the KPF derive from the maintenance of perforator vascular territories, perforosomes, permitting increased flap viability. In turn, this allows for more aggressive undermining in sites away from perforators when greater skin mobilization is necessary. Furthermore, the KPF is relatively easy to perform leading to shorter operative times and no postoperative monitoring period. There are basically 4 different types of keystone flaps in order of increasing undermining and disturbance of underlying fascia. These different classifications of KPFs may be used in different anatomical locations over the entire body based on skin laxity and defect size/depth. Numerous advancements and modifications have been documented adapting the KPF to specific conditions, including myelomeningoceles, and scrotal and lower eyelid defects. The purpose of this article is to provide an organized review of the KPF with emphasis on different classifications, applications, and limitations as well as an overview of the surgical technique. We have additionally included a discussion on KPF physiology and review of current literature.

Oncologic safety of propeller flap and free flap in reconstruction after soft tissue sarcoma resection

BACKGROUND AND OBJECTIVES

The propeller flap is a reliable option for reconstruction after soft tissue sarcoma resection. However, some parts of the resection margin may move away from its original position during flap rotation and thus can be excluded from the clinical target volume of adjuvant radiotherapy. This study aimed to evaluate local recurrence after soft tissue sarcoma resection with propeller flap or free flap reconstruction.

METHODS

Patients who underwent resection of soft tissue sarcoma followed by a free flap or propeller flap reconstruction and adjuvant radiotherapy at a single institution were retrospectively reviewed.

RESULTS

The 1- and 3-year local control rates were 94.6% and 88.6% in the free flap group vs 90.6% and 87.5% in the propeller flap group, without statistical significance. There were no statistically significant differences in 5-year local recurrence-free survival (88.6% vs 87.5%) and disease-free survival (82.5% vs 74.8%) between the groups.

CONCLUSIONS

Although there was no significant difference in local control and disease-free survival rates between propeller flap and free flap reconstruction after soft tissue sarcoma resection, a multidisciplinary approach is needed to obtain surgical information for determining the accurate clinical target volume of adjuvant radiotherapy and the area for meticulous follow-up postoperatively.

Keystone design perforator island flap in facial defect reconstruction

Facial defect coverage is a common subject in the field of reconstructive surgery. There are many methods for facial defect reconstruction, and reconstructive surgeons should choose the most appropriate method on a case-by-case basis to achieve both functional and aesthetic improvement. Among various options for facial reconstruction, the local flap technique is considered the best reconstructive modality to provide good tissue matches of color and texture, which is consistent with the ideal goal of reconstruction (replacement of like-with-like). Keystone design perforator island flap (KDPIF), devised by Behan in 2003, has been applied to various fields of reconstructive surgery in the past decade due to its design simplicity, robust vascular supply, and reproducibility. Several studies have reported KDPIF reconstruction of facial defects, such as large parotid defects, small-to-moderate nasal defects, and eyelid defects. However, KDPIF has been used relatively less in facial defects than in other body regions, such as the trunk and extremities. The purpose of this review is to provide an organized overview of facial KDPIF reconstruction including the classification of KDPIF, modifications, physiology, mechanism of flap movement, consideration of facial relaxed skin tension lines and aesthetics, surgical techniques, clinical applications, and precautions for successful execution of KDPIF reconstruction.

Best Local Flaps for Lower Extremity Reconstruction

Supplemental Digital Content is available in the text.

The ideal reconstruction of lower limb defects should replace like with like and minimize morbidity to the donor site, achieving the best possible esthetic and functional outcome. The goal is to obtain stable healing and to resume daily life in an efficient manner. Although the classical local flaps such as gastrocnemius, soleus muscle flap, and the reverse sural flap have allowed to achieve those goals, perforator flaps are now added on to the armamentarium in lower extremity reconstruction using local flaps. A perforator-based local flap, such as a propeller or keystone flap, has made reconstruction efficient while further reducing donor-site morbidity. This article aims to provide a useful review of the best available local flaps for lower limb defects.

V-Y Hemi-keystone Advancement Flap: A Novel and Simplified Reconstructive Modification

Background

The keystone perforator flap design has been gaining popularity for reconstruction of cutaneous defects due to its robust vascular supply and high rates of flap survival. However, the design requires significant tissue mobilization relative to the defect and is consequently technically demanding, time intensive, and has associated morbidity. We present a novel, simplified modification of the keystone flap that may increase its reconstructive applications.

Methods

A retrospective chart review was conducted of patients who underwent V-Y hemi-keystone advancement flap reconstruction of cutaneous defects by a single surgeon. Outcomes of interest included wound healing complications.

Results

Eighty-six consecutive V-Y hemi-keystone advancement flaps were performed with an overall complication rate of 7% (6/86). Reconstruction sites included lower extremities (75/86, 87.2%), upper extremities (9/86, 10.5%), and the trunk (2/86, 2.3%). Mean follow-up time was 26.3 weeks. Four out of 5 surgical site infections occurred on lower extremity wounds. There were no cases of complete or partial flap loss.

Conclusions

The current series presents a simplification of the traditional keystone flap that decreases surgical complexity and time required for successful reconstruction of cutaneous defects, especially in challenging wounds on the lower extremities. The complication rates were similar, or lower, than previously reported series of keystone flap reconstructions. The consistently favorable outcome of this technique supports the integration of the V-Y hemi-keystone advancement flap into reconstructive surgery.

Use of the Keystone Perforator Island Flap in the treatment of chronic lower extremity wounds complicated by osteomyelitis

INTRODUCTION

Reconstruction of chronic lower extremity wounds can be especially challenging when these wounds are complicated by osteomyelitis. They require the joint expertise of plastic and orthopaedic surgeons.

METHODS

We report our experience using the Keystone Perforator Island Flap following wound and bone debridement as a valuable surgical tool for coverage of complex wounds with bone infection.

RESULTS

Twelve patients underwent similar procedures with overall good outcomes, although two patients experienced a complication, specifically partial flap necrosis and wound dehiscence subsequent to recurrent osteomyelitis. We also reviewed the underlying physiological mechanisms of employing the Keystone flap in order to demonstrate its advantages and efficacy.

CONCLUSION

Our results confirm that the Keystone flap can be a safe, reliable and effective method for coverage of soft tissue defects and the preservation of bone integrity in the management of patients with chronic osteomyelitis.

Successful application of modified keystone flaps following skin tumor ablation

Skin cancer and precancerous skin lesions cause significant soft-tissue defects following tumor ablation. Recently, keystone flaps have gained popularity due to their simplicity, versatility, and reliability.We evaluated the efficacy of modified keystone flaps for soft-tissue reconstruction following skin tumor ablation in 2 medical centers.We reviewed the medical records of patients who received modified keystone flaps following the removal of skin tumors from January 2017 to December 2017. The diagnosis, site, flap size, and complications were recorded.Forty-one modified keystone flaps were evaluated, and the wound dimensions ranged from 1 cm × 1 cm to 18 cm × 9.5 cm, with an average size of 9.8 cm × 6.4 cm. With our selection strategy, specific modified keystone flaps were designed for the soft-tissue defects. The flap dimensions ranged from 2.2 cm × 1 cm to 26 cm × 10 cm, with an average size of 14.3 cm × 7.5 cm. Two patients developed minor wound dehiscence (4.9%), and 1 patient developed partial flap loss (2.4%), but all of these patients healed after local wound care without the need for surgical intervention.Our selection strategy for modified keystone flaps is a feasible and reliable option for reconstruction following skin tumor excision.

Objective and Patient-reported Assessments of Skin Grafts and Keystone Flaps-A Pilot Retrospective Cohort Study

Background:

The keystone perforator island flap provides a versatile form of reconstruction. Perceived benefits include better donor-recipient color match, less contour defect, and fewer complications. To date, there has been no high-quality evidence comparing keystone flaps to split-thickness skin grafts (SSG) from both a qualitative and quantitative point of view.

Methods:

The Objective and Patient Reported Assessments of Skin grafts versus Keystone flap cohort study compares keystone flaps with SSGs for the reconstruction of skin cancer defects. Patient-reported outcome measures were collected using the EuroQol 5 dimension scale and Patient and Observer Scar Assessment Scale (POSAS) questionnaires. Objective assessments of skin quality were assessed with the Courage and Khazaka system. Cost analysis was also performed.

Results:

Thirty-eight patients were studied: 20 keystone flaps and 18 SSGs. The keystone group had higher EuroQol 5 dimension scale scores (keystone median = 1.0; SSG median = 0.832; P = 0.641) indicating better general quality of life and lower POSAS scores indicating better disease/condition specific quality of life (keystone mean = 27.7; SSG mean = 35.7; P = 0.323). Observer POSAS scores were significantly lower in the keystone group compared with the SSG group (keystone mean = 10.889; SSG mean = 17.313; P < 0.001). Preservation of sensation was significantly better in keystone flaps (P = 0.006). There was an average £158/$207 (15%) saving when performing a keystone flap.

Conclusion:

This pilot study demonstrates a number of possible benefits of keystone flaps over SSGs. The results demonstrate the need for further research comparing these reconstructive options. We propose a prospective, controlled study using the methods developed in this pilot study.

Relaxed skin tension line-oriented keystone-designed perforator island flaps considering the facial aesthetic unit concept for the coverage of small to moderate facial defects

A variety of reconstructive options including skin grafts, loco-regional flaps, and free flaps exist for the coverage of facial defects. Each technique has advantages and disadvantages. In this study, we present our experience with relaxed skin tension line (RSTL)-oriented, keystone-designed perforator island flap (KDPIF) reconstructions, in consideration of the facial aesthetic unit concept for coverage of small to moderate facial defects.Between May 2016 and February 2018, 17 patients (11 men and 6 women), with an average age of 63.53 years (range: 37-83 years) underwent KDPIF reconstructions to cover facial defects. We performed the KDPIF reconstructions in consideration of the RSTLs and facial aesthetic unit concept. We retrospectively reviewed the defect causes, locations, and sizes, and flap sizes, types, and survivals, as well as the complications. Cosmetic outcomes were evaluated using the Harris 4-stage scale from 3 independent plastic surgeons' point of view, and postoperative satisfactory surveys from all patients.All defects were successfully covered with KDPIF. The defect sizes varied from 1.5 × 1.5 cm to 3 × 3.5 cm. The flap sizes varied from 1.5 × 3 cm to 3 × 5.5 cm. All flaps fully survived and there were no postoperative complications. The average subjective patient satisfaction score was 8.29 (range: 7-10) and the objective cosmetic outcomes were favorable (fair, good, or excellent).Considering its simplicity and safety, the KDPIF is a good reconstruction option with few complications and high reproducibility. The RSTL-oriented KDPIF reconstruction is a good reconstructive option for covering small to moderate facial defects with superior aesthetic outcomes.