Utility and Outcomes of the Keystone Perforator Island Flap for the Reconstruction of Various Anatomical Locations: A Prospective Study

doi:10.21203/rs.3.rs-4959310/v1

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Utility and Outcomes of the Keystone Perforator Island Flap for the Reconstruction of Various Anatomical Locations: A Prospective Study

https://doi.org/10.21203/rs.3.rs-4959310/v1

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Background

In Yemen's resource-constrained setting, the incidence of wounds resulting from injuries and accidents is high, placing a significant burden on the limited plastic surgery infrastructure. Advanced centers for microsurgical reconstruction are lacking, and expertise in free flaps is limited. Local flaps, while widely used, are complex and associated with high complication rates. This study evaluated the effectiveness and outcomes of the Keystone Island perforator flap (KIPF) technique as an alternative method for soft tissue reconstruction.

Methods

This prospective study included 35 patients who underwent KPIF for various defects. Demographic characteristics, intraoperative variables, postoperative outcomes, and aesthetic outcomes (assessed via the Patient and Observer Scar Assessment Scale (POSAS)) were evaluated. Factors influencing success rates and complications were analyzed.

Results

The mean age of the patients was 29 ± 11.75 years, with males comprising 86% of the sample. Trauma was the leading cause of tissue defects (77.1%). The most common defect locations were the leg (57.14%) and foot (11.43%). The mean operative time was 73.57 minutes. Postoperatively, 26% of patients experienced complications, with flap dehiscence being the most common complication (11.43%). The flap survival rate was 97%, and complete wound healing was observed in 91.4% of the patients within a median of 16 days. Scar assessments indicated satisfactory aesthetic outcomes with minimal differences from those of normal skin.

Conclusion

The KIPF technique demonstrated high effectiveness and reliability in soft tissue reconstruction, particularly in settings with limited resources and expertise. Its ease of use, minimal postsurgical care, and high flap survival rates make it a valuable alternative to traditional methods. This study supports the adoption of KIPF as a standard practice in similar resource-constrained environments.

Plastic & Reconstructive Surgery

Keystone Island perforator flap

soft tissue reconstruction

trauma

Yemen

plastic surgery

resource-constrained settings

Soft tissue reconstruction involves a variety of reconstructive options, each influenced by critical factors such as the size and location of the defect, the condition of the underlying structures, and the availability of local soft tissue [1, 2]. In Yemen, a resource-constrained setting, the high incidence of wounds resulting from injuries and accidents imposes a significant burden on the plastic surgery team. The absence of advanced centers for microsurgical reconstruction and the limited expertise in free flaps necessitate reliance on local flaps for reconstructing various parts of the body [3].

Local flaps, though seemingly straightforward, require a steep learning curve and are associated with high complication rates, particularly in less experienced hands [4]. To address these challenges, the Keystone Island Perforator Flap (KIPF) technique has emerged as a valuable method in plastic surgery, particularly in resource-limited settings such as Yemen. It offers a reliable, easy, and quick solution for fasciocutaneous closure with minimal postsurgical care, making it a practical alternative to more complex procedures and locoregional flaps [5, 6]. The KIPF is noted for its advantages, such as ease of dissection, preservation of perforating vessels, and reduced donor site morbidity, with studies reporting high success rates and patient satisfaction [7, 8]. However, complications such as flap necrosis and wound infection can occur and are influenced by factors such as perforator anatomy, flap design, and surgical technique [9–11]. The KIPF has been successfully applied to various anatomical regions, showing its versatility, particularly in reconstructing defects of the trunk and lower extremities [10, 12–15].

Given the scarcity of research on KIPF in Yemen, this study aimed to evaluate its effectiveness across various anatomical locations. By assessing the success rate, aesthetic outcomes, and complications associated with KIPF, this study aims to demonstrate its utility and safety in resource-limited environments. The findings will guide surgical decision-making and improve patient care, contributing to the advancement of reconstructive surgery in similar settings.

This was a prospective case series study conducted from February 2021 to December 2023 at three plastic and reconstructive surgery departments: Police Typical Hospital, Al-Moutawakel Hospital, and Al-Khamsin Hospital in Sana'a city, Yemen.

The study included patients with soft tissue defects in various anatomical locations who underwent reconstruction via the KIPF. Patients were eligible if they had soft tissue defects suitable for KIPF, provided informed consent, and were capable of complying with follow-up visits. The exclusion criteria included patients who did not undergo reconstruction via the KPIF, those who did not provide informed consent, or those with soft tissue defects not appropriate for the KPIF due to size, location, or comorbid conditions.

Patient demographic data, including age, sex, and underlying etiologies of the soft tissue defects, were collected. Detailed information on the defect characteristics, such as size, location, and associated injuries, was documented. Surgical details, including the type of flap design, dimensions, and intraoperative findings (such as blood loss and operative time), were meticulously recorded. Postoperative outcomes, such as complications, flap survival, wound healing time, and length of hospital stay, were monitored. Data collection was standardized via structured forms to ensure consistency.

The primary outcome was the success rate of the KIPF procedure, which was defined as complete flap survival without necrosis or significant complications. Aesthetic outcomes were evaluated via the Patient and Observer Scar Assessment Scale (POSAS 3.0), which includes both patient-reported and observer-reported assessments of scar appearance[16]. The secondary outcomes included complication rates, which were categorized as minor (e.g., partial flap necrosis, seroma formation) or major (e.g., complete flap failure, significant infection).

The surgical technique began with careful preoperative planning, where the flap was designed to align with the relaxed skin tension lines, reducing tension on the closure and enhancing flap mobility. The long axis of the flap was aligned parallel to the long axis of the defect. The short axis was projected from the defect edge, creating a keystone shape with a convex line parallel to the defect edge. After the flap was marked, the skin and subcutaneous tissue were incised following predetermined lines. Dissection was performed meticulously to preserve the perforating vessels, ensuring adequate blood supply to the flap. The flap was then mobilized as an island, carefully advanced into the primary defect, and secured in place with sutures, paying attention to the tension at the edges to avoid ischemia. For certain defects, undermining the surrounding tissue is necessary to facilitate flap movement and reduce tension. Hemostasis was meticulously achieved throughout the procedure to minimize blood loss. A surgical drain was selectively placed in cases where fluid accumulation was anticipated, particularly in larger flaps or where significant undermining was performed. The wound was closed in layers, with attention given to minimizing tension at the closure site to promote healing and reduce the risk of dehiscence (Fig. 1).

Patients underwent a comprehensive follow-up protocol to monitor healing and detect any complications early. During the first two weeks after surgery, patients were seen every three days for wound assessment, dressing changes, and suture removal. After the initial period, monthly visits were scheduled for six months to evaluate long-term outcomes, including flap survival, wound healing, and scar maturation. During these follow-up visits, the aesthetic outcomes of the scar were assessed via the POSAS scale. Patients completed the Patient Scar Assessment Scale (PSAS), which provides their subjective evaluation of the scar's appearance, including factors such as color, pliability, and thickness. An experienced plastic surgeon who was not involved in the surgery completed the Observer Scar Assessment Scale (OSAS) to provide an objective assessment of the scar[16]. This approach ensured a comprehensive evaluation of the scar from both patient and clinician perspectives. In cases where complications such as partial flap necrosis, seroma formation, or infection were observed, appropriate interventions were implemented promptly. For example, partial flap necrosis can be managed with bedside debridement and local wound care, while seromas can be aspirated under sterile conditions. Any signs of infection were treated with antibiotics, and more significant issues, such as flap failure, were managed with revision surgery as needed.

Statistical analysis was performed via SPSS version 26. Descriptive statistics were used to summarize patient demographics, intraoperative details, and postoperative outcomes. To compare success rates between different groups (e.g., based on defect location and flap size), chi-square tests and Fisher's exact tests were employed. Univariate analysis was conducted to identify factors associated with flap success, such as defect size, location, and patient comorbidities. Complication rates were calculated and compared via appropriate statistical methods. The results of the aesthetic assessments were analyzed by calculating the mean scores on the POSAS scale, and interrater reliability was evaluated via intraclass correlation coefficients (ICCs). A p value of less than 0.05 was considered statistically significant.

The study received ethical approval from the Yemeni Board of Plastic Surgery and administrative approval from affiliated hospitals in Sana’a, Yemen. Informed written consent was obtained from all participants, ensuring that their participation was voluntary and that their personal information was kept confidential. The participants were informed of their right to withdraw from the study at any time without any impact on their medical care.

The study included 35 patients who underwent KIPF for reconstruction at various anatomic locations. The mean age was 29 ± 11.75 years, ranging from 10–60 years, with 22.9% of patients aged ≤ 18 years, 74.3% aged 19–50 years, and 2.9% aged > 50 years. The sex distribution was male (85.7%), with 14.3% female patients. The special habits of the participants included qat chewing (74.3%), smoking (34.3%), and Shama use (25.7%). Most patients (80%) had no comorbidities, whereas 5.7% had diabetes mellitus (DM) and lower limb paralysis each, with other conditions observed in 2.9% of patients. Trauma or accidents accounted for 77.1% of the tissue defects, followed by pressure sores and burns/scarring (5.7% each) (Table 1).

Table 1

Demographic characteristics (N = 35)
Characteristic	Category	Frequency	Percent
Age Group	≤ 18 years	8	22.9
	19–50 years	26	74.3
	> 50 years	1	2.9
Mean ± SD		29 ± 11.75
Sex	Male	30	85.7
	Female	5	14.3
Special Habits	Qat chewing	26	74.3
	Smoking	12	34.3
	Shama using	9	25.7
Comorbidities	No comorbidity	28	80.0
	DM	2	5.7
	Lower limbs paralysis	2	5.7
	Hypertension (HTN)	1	2.9
	Deep venous thrombosis (DVT)	1	2.9
	Cerebrovascular accident (CVA)	1	2.9
	Psychological issues	1	2.9
Etiology of Defect	Trauma/accident	27	77.1
	Pressure sore	2	5.7
	Burn/scarring	2	5.7
	Infection/osteomyelitis	1	2.9
	Oncologic cause	1	2.9
	Ulcer	1	2.9
	Myelomeningocele	1	2.9

The preoperative assessment indicated that the leg was the most common defect location, accounting for 57.14% of the defects, followed by the foot (11.43%) and the thigh and back (8.57% each). Other locations were less common. Primary closure attempts were made in 25.71% of the patients. The mean size of the first defects was 4.44 cm in width and 8.74 cm in length, whereas the second defects had a mean width of 4 cm and a mean length of 7.67 cm (Table 2).

Table 2

Defect Locations and Sizes (N = 35)
Characteristic	Category	Frequency	Percent
Defect Location	Leg	20	57.14
	Foot	4	11.43
	Thigh	3	8.57
	Back	3	8.57
	Buttock	2	5.71
	Upper Limbs	2	5.71
	Abdomen	1	2.86
Primary Closure Attempts	Yes	9	25.71
Defect Sizes	1st Defect Width (Mean ± SD)	4.44 ± 1.46
	1st Defect Length (Mean ± SD)	8.74 ± 2.51
	2nd Defect Width (Mean ± SD)	4 ± 2
	2nd Defect Length (Mean ± SD)	7.67 ± 1.15
	Median Number of Defects	1 (1–2)

The mean operative time was 73.57 minutes. Behan's classification indicated that Type IIA was the most common flap type (54.29%), followed by Type I (22.86%) and Type III (14.29%). The mean size of the first flap was 6.03 cm in width and 10.94 cm in length, whereas the second flap had a mean width of 4.63 cm and a length of 8.29 cm (Table 3).

Table 3

Intraoperative assessment (N = 35)
Intraoperative Variable	Category	Frequency	Percent
Operative Time (Mean ± SD)		73.57 ± 17.56
Behan's Classifications	Type IIA	19	54.29
	Type I	8	22.86
	Type III	5	14.29
	Type IIB	2	5.71
	Type IV	1	2.86
Total Number of Flaps		1 (1–2)
Flap Sizes	1st Flap Width (Mean ± SD)	6.03 ± 1.77
	1st Flap Length (Mean ± SD)	10.94 ± 3.05
	2nd Flap Width (Mean ± SD)	4.63 ± 2.50
	2nd Flap Length (Mean ± SD)	8.29 ± 2.06
Flap Hemodynamic Change	Red Dot Sign	35	100

Postoperative complications occurred in 26% of patients, with flap dehiscence being the most common (11.43%). Other complications included epidermolysis, marginal flap necrosis, venous congestion, seroma, and flap infection (each 2.86%). Reoperation was necessary for 5.7% of patients. The management strategies included bedside closure of dehiscent flaps (8.56%), skin grafting (2.86%), and other interventions. The median length of stay was 3 days, with most flaps fully surviving (97%) and complete wound healing occurring in 91.4% of the patients within a median time of 16 days (Table 4).

Table 4

Postoperative Outcomes and Complications (N = 35)
Postoperative Variable	Category	Frequency	Percent
Postop Complications	Flap Dehiscence	4	11.43
	Epidermolysis/Skin Necrosis	1	2.86
	Marginal Flap Necrosis	1	2.86
	Venous Congestion	1	2.86
	Seroma	1	2.86
	Flap Infection	1	2.86
	Reoperation	2	5.7
Management of Complications	Bedside Closure of Dehiscent Flap	3	8.56
	Full Thickness Skin Graft	1	2.86
	Bedside Seroma Evacuation	1	2.86
	Debridement and Readvancement	1	2.86
	Conservative Management	3	8.56
Postoperative Outcomes	LOS (Median, IQR)	3 (2–7) days
	Flap Survival	Fully Survived	34
		Partially Survived	1
	Time to Complete Healing (Median, IQR)	16 (12–30) days

Aesthetic outcomes according to the POSAS

Patient Scar Assessment Scale (PSAS)

The reliability of the Patient Scar Assessment Scale (PSAS) was confirmed, with a high Cronbach's alpha of 0.907 for 17 items, whereas the observer-reported outcome scale also demonstrated excellent reliability, with a Cronbach's alpha of 0.913 across 10 items. Descriptive analysis revealed that patients reported minimal aesthetic concerns and physical discomfort related to their scars. The scars were assessed as only slightly different from normal skin in terms of color, shininess, elevation, hardness, irregularity, and edge appearance (Table 5). Additionally, patients experienced minimal physical discomfort, including rare instances of sensitivity, numbness, and pain. Overall, the mean score of 1.69 (SD = 0.58) reflects positive aesthetic and physical outcomes for the scars (Table 6).

Table 5

Patient scar assessment at the current moment according to PSAS
Question	Severely	Moderately	Minimally	Not	Mean	SD
Color difference	1 (3%)	13 (37%)	21 (60%)	0 (0%)	2.43	0.56
Shininess	1 (3%)	3 (9%)	16 (46%)	15 (43%)	1.71	0.75
Raised/sunken scar	0 (0%)	5 (14%)	25 (71%)	5 (14%)	2.00	0.54
Hardness	1 (3%)	12 (34%)	15 (43%)	7 (20%)	2.20	0.80
Irregularity	0 (0%)	11 (31%)	22 (63%)	2 (6%)	2.26	0.56
Stretched or widened	0 (0%)	7 (20%)	13 (37%)	15 (43%)	1.77	0.77

Table 6

Patient scar assessment during the last week according to PSAS
Question	Moderately	Minimally	Not	Mean	SD
Sensitivity	3 (9%)	8 (23%)	24 (69%)	1.40	0.65
Numbness	1 (3%)	16 (46%)	18 (51%)	1.51	0.56
Pain	0 (0%)	4 (11%)	31 (89%)	1.11	0.32
Shooting sensation	1 (3%)	5 (15%)	28 (82%)	1.21	0.48
Burning sensation	0 (0%)	21 (60%)	14 (40%)	1.60	0.50
Itch	4 (11%)	23 (66%)	8 (23%)	1.89	0.58
Tingling	0 (0%)	5 (16%)	27 (84%)	1.16	0.37
Scar tightness at rest	2 (6%)	13 (37%)	20 (57%)	1.49	0.61
Tightness with movement	9 (26%)	17 (49%)	9 (26%)	2.00	0.73
Fragility	1 (3%)	4 (11%)	30 (86%)	1.17	0.45
Dryness	5 (14%)	16 (46%)	14 (40%)	1.74	0.70

Observer scar assessment (OSAS)

The observer-reported outcome scale exhibited excellent internal consistency, with a Cronbach's alpha of 0.913 across the 10 items, confirming its reliability. Descriptive analysis of the observer scale revealed that scars were characterized by hypopigmentation (68.6%), pale/white vascularity (74.3%), depressed surface level (80%), and irregular texture (88.6%) (Table 7). Most observers rated the overall quality of scars as minimally different from that of normal skin, with an overall mean score of 2.15 (SD = 0.65) across various characteristics, suggesting favorable healing progress and acceptable cosmetic outcomes (Table 8).

Table 7

Descriptive Analysis of Scar Characteristics According to OSAS Status
Variable	Category	Frequency	Percent (%)
Pigmentation	Hypopigmentation	24	68.6
	Hyperpigmentation	2	5.7
	Mixed	9	25.7
Vascularity	Pale/White	26	74.3
	Pink	8	22.9
	Red	2	5.7
	Purple	1	2.9
Surface Level	Elevated	7	20.0
	Depressed	28	80.0
Texture	Irregular	31	88.6
	Overly Smooth	4	11.4

Table 8

Observer's scar assessment according to OSAS scale scores
Question	Severely	Moderately	Minimally	Not	Mean	SD
Overall quality	1 (3%)	14 (40%)	20 (57%)	0 (0%)	2.46	0.56
Pigmentation	1 (3%)	10 (29%)	24 (69%)	0 (0%)	2.34	0.54
Vascularity	1 (3%)	4 (11%)	28 (80%)	2 (6%)	2.11	0.53
Surface level	0 (0%)	9 (26%)	20 (57%)	6 (17%)	2.09	0.66
Scar Texture	2 (6%)	11 (31%)	21 (60%)	1 (3%)	2.40	0.65
Firmness	1 (3%)	11 (31%)	22 (63%)	1 (3%)	2.34	0.59
Adherence	0 (0%)	6 (17%)	15 (43%)	14 (40%)	1.77	0.73
Scar tension	0 (0%)	11 (31%)	16 (46%)	8 (23%)	2.09	0.74
Edges widened	0 (0%)	9 (26%)	13 (37%)	13 (37%)	1.89	0.80
Scar marks	1 (3%)	5 (14%)	20 (57%)	9 (26%)	1.94	0.73

Correlation between OSAS and PSAS

Spearman's correlation analysis revealed significant correlations between patient-reported outcomes and observer assessments, indicating strong agreement between patients' perceptions and observers' evaluations, particularly in areas such as color differences, firmness, and scar tension (Table 9).

Table 9

Selected Spearman's correlation coefficients
Patient-Reported Outcome	Observer-Reported Outcome	Correlation Coefficient	p value
Color Difference	Overall Quality of the Scar	0.600**	0.000**
Shininess	Firmness	0.616**	0.000**
Surface Irregularity	Scar Texture	0.425*	0.011*
Edges Widened	Adherence	0.437**	0.008**
Tension at Rest	Scar Tension	0.780**	0.000*

Presentation of some cases

Patient 1. A 13-year-old male patient presented after a road traffic accident with a crush injury wound measuring approximately 6*4 cm on the dorsum of the right foot with exposed tendons (Fig. 2).

Patient 2. An 18-year-old patient presented with a left Achilles tendon injury and separation from the insertion site following RTA, with a soft tissue defect measuring 7*4 cm (Fig. 3).

Patient 3. A 60-year-old patient, a known case of HTN and DM, presented with post-RTA trauma to the left leg, resulting in a compound tibial and fibular fracture with associated soft tissue and skin necrosis with a soft tissue defect measuring 10*4 cm (Fig. 4).

Patient 4. A 30-year-old patient with a diagnosis of post RTA (RTA) left Achilles tendon injury and avulsion from insertion, along with an accompanying overlying skin defect (Fig. 5).

Patient 5. A 40-year-old male with a history of smoking and qat chewing presented with multiple traumas, including a left femur open fracture and right posterior thigh skin defect, after a gunshot wound. Additionally, the patient had a lower abdominal wall wound. Reconstruction involved the use of a Type 1 keystone flap to cover both the thigh and the abdomen. The patient demonstrated satisfactory wound healing with progressive scar maturation over time (Fig. 6).

Patient 6. A 41-year-old male patient sustained gunshot injury resulting in a proximal right tibia open fracture and a large skin defect. A type 2a keystone flap was harvested from the medial aspect of the proximal leg and extended posteriorly to enhance vascularity from the proximal sural nerve. Postoperative follow-up at five months revealed successful flap integration and ongoing healing, with the external fixator remaining in place (Fig. 7).

Patient 7. A 25-year-old male experienced a bomb explosion that resulted in significant soft tissue loss over the sacral triangle and the upper part of the left gluteal region. Surgical repair included restoring the proximal attachment of the left superficial gluteal muscles. A type 1 keystone island perforator flap was used to close the defect and was designed to restore the intergluteal cleft. The postoperative outcome revealed effective coverage of the defect with good healing (Fig. 8).

Case 8

A 12-year-old female presented with a congenital melanocytic nevus on the medial aspect of the left thigh. Surgical intervention involved an elliptical excision of the lesion, followed by elevation of a type 1 keystone island flap over the anterior side of the thigh to close the defect. The patient had favorable healing outcomes, with satisfactory wound closure observed by the fourth postoperative day (Fig. 9).

Patient 9. An 11-month-old female was diagnosed with a myelomeningocele, which was surgically repaired by a neurosurgeon. The subsequent defect was covered with a Type 2a keystone flap designed along the lumbar nerve axis. The flap was advanced, and the defect was closed, with the patient showing positive healing progress at the two-week postoperative follow-up (Fig. 10).

KIPF has proven to be a highly effective and versatile technique for reconstructive surgery, particularly in resource-constrained settings such as Yemen. This study's findings align closely with a substantial body of literature, reinforcing the reliability and broad applicability of the KIPF across various anatomical locations and clinical scenarios.

Our study revealed a high flap survival rate of 97% and a wound healing rate of 91.4% within a median of 16 days. These outcomes are consistent with those of Khouri et al. (2011), who reported a 97% reconstructive success rate for KIPF in treating large defects of the trunk and extremities[1]. Similarly, Huang et al. (2017) highlighted the high success rates and low technical complexity of KIPF in lower extremity reconstructions[17].

The versatility of KIPF is well documented, with successful applications in combat-related lower limb injuries [18], chronic wounds complicated by osteomyelitis [19], and head and neck reconstructions [2]. These findings align with our study, which revealed successful KIPF applications, primarily in the leg (57.14%) and foot (11.43%).

The postoperative outcomes in our study, including the high flap survival rate and minimal complications, mirror those reported in the literature. Weinberg et al. (2022) noted a 98% overall success rate in a systematic review of KIPF applications, reinforcing the robustness of our findings[20]. However, our study’s complication rate of 26%, including flap dehiscence (11.43%) and wound infections, is higher than the 9.6% reported by Huang et al. (2017)[17]. This discrepancy might be due to the challenging clinical environment in Yemen, where advanced postoperative care may be limited.

Scar quality assessments via the Patient Scar Assessment Scale (PSAS) and Observer Scar Assessment Scale (OSAS) in our study indicated minimal differences from normal skin and satisfactory aesthetic outcomes. These results are corroborated by Virág et al. (2022), who reported that KIPFs provide effective wound closure with minimal donor site morbidity and high patient satisfaction[6]. The use of the PSAS and OSAS has been validated by studies such as Bianchi et al. (2010) and van der Wal et al. (2011), which emphasize the reliability of these tools in evaluating scar quality[21, 22].

Comparative studies have shown that KIPF offers several advantages over traditional free flaps, including shorter operative times, lower costs, and shorter hospital stays [23]. These benefits are particularly relevant in resource-constrained settings. Modifications to the KIPF design, such as the bipedicled KPIF for chronic wound coverage [24] and the boat-shaped flap to reduce tension [25], have improved outcomes in complex wounds, including those resulting from large oncologic resections and irradiation [26].

Our findings on the demographic characteristics of patients, young males (mean age 29 years), align with other studies highlighting similar trends in trauma-related reconstructions. The KIF technique has been particularly beneficial for elderly patients, offering quick recovery times and low complication rates [27]. Factors impacting outcomes include comorbidities such as coronary artery disease, which is associated with increased rates of wound healing complications and surgical site infections [2]. Despite less favorable viscoelastic properties in patients with colored skin, the KIF technique has been successfully applied, demonstrating its adaptability and effectiveness [28]. Additionally, Yoon et al. (2017) reported promising results in treating pretibial defects in patients with comorbidities, further highlighting the versatility of the technique[29].

Our study revealed that 80% of patients had no comorbidities, which may have contributed to the high flap survival rate and overall positive outcomes. The presence of comorbidities such as diabetes mellitus and lower limb paralysis, noted in 5.7% of participants, did not significantly impact the overall success of the KIF procedures. This aligns with the findings of Yoon et al. (2017) and Lanni et al. (2017), who reported that while comorbidities can increase complication rates, the KIF technique remains effective even in these challenging cases[2, 29].

The KIF has demonstrated promising long-term outcomes across various reconstructive procedures, reinforcing its reliability and effectiveness. In nasal defect reconstruction, KIFs have been shown to respect aesthetic subunits, providing satisfactory outcomes at the 6-month follow-up [30]. Similarly, Formentin et al. (2019) reported reliable results with no major complications in large myelomeningocele closures using KIF[31]. The technique has also proven effective in melanoma management, yielding pain-free and aesthetically pleasing results [32].

The efficacy of KIFs is attributed to their unique design, which allows for tension redistribution and improved blood supply [33]. A novel modification, the UQ flap, has further demonstrated favorable results in leg wound closure with minimal complications [5]. Behan (2008) emphasized the reliability of fascially based flaps and the clinical principles underlying island flap efficacy, reinforcing the long-term success of these techniques[34].

Studies have consistently shown high success rates for KIFs, ranging from 95–98% [20, 35]. Compared with skin grafts, these flaps offer superior aesthetic outcomes, providing better donor‒recipient color matching and fewer contour defects [36]. Patients report high levels of satisfaction with both functional and cosmetic results, a sentiment echoed by Yoon et al. (2017, 2019), who documented favorable patient-reported outcomes across multiple anatomical locations[29, 37].

The KIF technique is particularly advantageous for elderly patients, offering a versatile and effective reconstructive option for various soft tissue defects [27]. Its application spans the trunk, extremities, and face [1, 37], highlighting its versatility. Moreover, compared with more complex microsurgical techniques, KIFs are associated with shorter operative times, ease of use, and cost-effectiveness [1, 36].

While minor complications can occur, overall complication rates are low, making KIFs a reliable choice for soft tissue reconstruction [20, 38]. The high success rates, coupled with positive long-term patient satisfaction, underscore the effectiveness and dependability of the Keystone Island flap technique in reconstructive surgery.

In Yemen's resource-constrained setting, where there is no advanced center for microsurgical reconstruction and expertise in free flaps is limited, the KIPF technique has emerged as a promising local flap method in plastic surgery, offering better outcomes than skin grafts or healing by secondary intention. Despite its promise, research on KIPF within China is scarce. Therefore, we explored the effectiveness and results of the KIPF across various anatomical locations. By evaluating the success rate, aesthetic outcomes, influential factors, and complications, our research aims to demonstrate the technique's growing utility and safety, providing a viable solution to overcome the challenges of limited resources.

The positive aesthetic outcomes in our study underscore the potential of keystone perforator island flaps to achieve not only reliable wound closure but also satisfactory cosmetic results. The flap design, which allows for local tissue rearrangement, minimizes the conspicuousness of the scar and contributes to excellent POSAS scores.

The use of both observer and patient-reported assessments in our study provides a comprehensive understanding of scar outcomes. The alignment of the observer and patient scores suggests a high level of agreement between the perceptions of the clinicians assessing the scars and the patients living with the scars. This agreement strengthens the validity of the findings and underscores the importance of incorporating patient perspectives in assessing outcomes.

While our prospective, multicenter study provides valuable insights into the use of KPIF in a resource-constrained setting, several limitations should be acknowledged. The small sample size of 25 patients may limit the precision of the outcome estimates and the generalizability of the findings. The lack of a control or comparison group restricts the ability to draw conclusions about the relative effectiveness and advantages of KPIF compared with alternative reconstructive options. While the 6-month follow-up period provides a reasonable assessment of early to intermediate outcomes, longer follow-up is needed to fully evaluate the durability of the outcomes and capture any late complications. The study's measurement of outcomes could be strengthened by the inclusion of more comprehensive and standardized measures, particularly regarding functional outcomes. The generalizability of the findings to settings with more advanced reconstructive capabilities or different patient populations is uncertain. Further research, including larger studies with comparison groups, longer follow-up periods, and more comprehensive outcome assessments, is warranted to fully elucidate the potential of KPIF in various contexts.

In conclusion, the KIPF technique demonstrates high effectiveness, versatility, and patient satisfaction in various reconstructive applications, particularly in resource-constrained settings. Its ability to achieve high flap survival rates, satisfactory aesthetic outcomes, and minimal complications makes it a valuable tool for plastic surgeons. The incorporation of modifications and innovations continues to enhance its utility, addressing the challenges presented by complex wounds and diverse anatomical locations.

This study demonstrates the usefulness of KPIF for reconstructing various defects in a resource-constrained setting, highlighting its reliability, versatility, and ability to achieve excellent aesthetic outcomes. These findings support the expanding utility and safety of KPIF in managing complex defects where microsurgical expertise is limited. Larger, longer-term studies with comparison groups are needed to fully establish the relative effectiveness and cost-effectiveness of KPIF.

KPIF	Keystone Perforator Island Flap
DM	Diabetes Mellitus
HTN	Hypertension
DVT	Deep Vein Thrombosis
POSAS	Patient and Observer Scar Assessment Scale
PSAS	Patient Scar Assessment Scale
OSAS	Observer Scar Assessment Scale
IQR	Interquartile Range
SPSS	Statistical Package for the Social Sciences

I would like to confirm that the legal guardians of all minors involved in this study provided written informed consent for their participation and for the publication of the study’s findings and any accompanying images. Measures were taken to ensure the exclusion of any potential patient identifiers from the report.

Acknowledgments

Not applicable.

Ethics approval and informed consent

Ethical approval for this study was obtained from the Ethical Committee of the affiliated hospitals in Sana'a, Yemen, in accordance with the 1964 Declaration of Helsinki and its subsequent amendments or comparable ethical standards. Informed consent was obtained from all participants.

Consent for publication

All patients provided written informed consent for the publication of this study and any accompanying images. Measures were taken to ensure the exclusion of any potential patient identifiers from the report.

Disclosure

The authors declare that they have no conflicts of interest.

Conflicts of interest

Nonfinancial competing interests

Funding disclosure

This study did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author Contributions

Y.A.A. contributed to the conceptualization, methodology, data curation, and writing of the original draft. M.Y.A. contributed to the methodology, data analysis, and writing. M.Y.W. contributed to the conceptualization, validation, and review of the manuscript. H.M.J. supervised, validated, and revised the manuscript. All the authors have read and approved the final version of the manuscript.

For correspondence: H.M.J.

Khouri JS, Egeland BM, Daily SD, Harake MS, Kwon S, Neligan PC et al (2011) The Keystone Island Flap: Use in Large Defects of the Trunk and Extremities in Soft-Tissue Reconstruction. Plast Reconstr Surg 127:1212–1221. https://doi.org/10.1097/PRS.0b013e318205f36f
Lanni MA, Van Kouwenberg E, Yan A, Rezak KM, Patel A (2017) Applying the Keystone Design Perforator Island Flap Concept in a Variety of Anatomic Locations. Ann Plast Surg 79:60–67. https://doi.org/10.1097/SAP.0000000000000995
Lo Torto F, Frattaroli JM, Kaciulyte J, Mori FLR, Troisi L, Ciudad P et al (2022) The keystone flap: A multicentric experience in elderly patients’ treatment. J Plast Reconstr Aesthetic Surg 75:226–239. https://doi.org/10.1016/j.bjps.2021.08.043
Virág TH, Muntean MV, Mihály AZ, Georgescu AV (2024) Experimental investigation of tension-reducing effectiveness of keystone perforator island flap. Med Pharm Rep 97:196–204. https://doi.org/10.15386/mpr-2679
Hassani M, Hertess I, Tucker S, Coetzer-Botha M, Kittler H, Rosendahl C (2022) The UQ Flap: A Novel Modification of the Keystone Flap. Plast Reconstr Surg Glob Open 10:e4619. https://doi.org/10.1097/GOX.0000000000004619
Virág TH, Muntean MV, Georgescu AV (2022) Minimizing donor-site morbidity following limbs’ injuries with keystone perforator island flap reconstruction. Wound Repair Regeneration 30:357–364. https://doi.org/10.1111/wrr.13007
Behan FC (2003) The Keystone Design Perforator Island Flap in reconstructive surgery. ANZ J Surg 73:112–120. https://doi.org/10.1046/j.1445-2197.2003.02638.x
Chopan M, Sayadi L, Buchanan PJ, Katz AJ, Mast BA (2019) Historical Roots of Modern Plastic Surgery. Ann Plast Surg 82:S421–S426. https://doi.org/10.1097/SAP.0000000000001666
Blackwell KE, Azizzadeh B, Ayala C, Rawnsley JD (2002) Octogenarian Free Flap Reconstruction: Complications and Cost of Therapy. Otolaryngology–Head Neck Surg 126:301–306. https://doi.org/10.1067/mhn.2002.122704
Mohan AT, Rammos CK, Akhavan AA, Martinez J, Wu PS, Moran SL et al (2016) Evolving Concepts of Keystone Perforator Island Flaps (KPIF): Principles of Perforator Anatomy, Design Modifications, and Extended Clinical Applications. Plast Reconstr Surg 137:1909–1920. https://doi.org/10.1097/PRS.0000000000002228
Behan F, Lo C (2009) Principles and Misconceptions Regarding the Keystone Island Flap. Ann Surg Oncol 16:1722–1723. https://doi.org/10.1245/s10434-009-0442-4
Cormack GC, Lamberty BG (1984) Fasciocutaneous vessels in the upper arm: application to the design of new fasciocutaneous flaps. Plast Reconstr Surg 74:244–250
Pelissier P, Gardet H, Pinsolle V, Santoul M, Behan FC (2007) The keystone design perforator island flap. Part II: clinical applications. J Plast Reconstr Aesthetic Surg 60:888–891. https://doi.org/10.1016/j.bjps.2007.03.023
Pawlak N, De La Cruz Ku G, Chatterjee A, Persing S, Homsy C (2024) The Keystone Perforator Island Flap: Review of Utility and Versatile Clinical Applications. Plast Reconstr Surg Glob Open 12:e5556. https://doi.org/10.1097/GOX.0000000000005556
Taylor GI, Palmer JH (1987) The vascular territories (angiosomes) of the body: experimental study and clinical applications. Br J Plast Surg 40:113–141. https://doi.org/10.1016/0007-1226(87)90185-8
Carrière ME, Mokkink LB, Tyack Z, Westerman MJ, Pijpe A, Pleat J et al (2023) Development of the Patient Scale of the Patient and Observer Scar Assessment Scale (POSAS) 3.0: a qualitative study. Qual Life Res 32:583–592. https://doi.org/10.1007/s11136-022-03244-6
Huang J, Yu N, Long X, Wang X (2017) A systematic review of the keystone design perforator island flap in lower extremity defects. Medicine 96:e6842. https://doi.org/10.1097/MD.0000000000006842
Sliesarenko SV, Badiul PA, Rudenko OI, Romanshuk MI Keystone perforator island flaps in the reconstruction of lower limb defects resulting from shrapnel and mine-explosive combat injuries. Case series. Gen Surg 2023:48–57. https://doi.org/10.30978/GS-2023-1-48
Al-Mousawi A, Sanese G, Baljer B, Lo Torto F, Hausien O, Perra A et al (2020) Use of the Keystone Perforator Island Flap in the treatment of chronic lower extremity wounds complicated by osteomyelitis. Injury 51:744–749. https://doi.org/10.1016/j.injury.2019.12.010
Weinberg M, Heiman AJ, DeSanti R, Lanni MA, Kouwenberg E, Van, Patel A (2022) Outcomes of the Keystone Island Perforator Flap: A Systematic Review. J Reconstr Microsurg 38:727–733. https://doi.org/10.1055/s-0042-1745744
Bianchi FA, Roccia F, Fiorini P, Berrone S (2010) Use of Patient and Observer Scar Assessment Scale for Evaluation of Facial Scars Treated With Self-Drying Silicone Gel. J Craniofac Surg 21:719–723. https://doi.org/10.1097/SCS.0b013e3181d841af
van der Wal MBA, Tuinebreijer WE, Bloemen MCT, Verhaegen PDHM, Middelkoop E, van Zuijlen PPM (2012) Rasch analysis of the Patient and Observer Scar Assessment Scale (POSAS) in burn scars. Qual Life Res 21:13–23. https://doi.org/10.1007/s11136-011-9924-5
Gabrysz-Forget F, Tabet P, Rahal A, Bissada E, Christopoulos A, Ayad T (2019) Free versus pedicled flaps for reconstruction of head and neck cancer defects: A systematic review. J Otolaryngol - Head Neck Surg 48. https://doi.org/10.1186/s40463-019-0334-y
Oh JM, Jwa SJ, Won JM, Baek WY, Hong JW, Lee WJ et al (2023) A bipedicled keystone perforator island flap: Pedicle division technique with enhanced advancement potential for chronic wound coverage. J Plast Reconstr Aesthetic Surg 86:239–245. https://doi.org/10.1016/j.bjps.2023.09.031
Fang S, Tang W, Li Y, Zhu W, Zhuang W, Xing X et al (2019) A novel modification of keystone flap for superficial defects repair. J Plast Reconstr Aesthetic Surg 72:848–862. https://doi.org/10.1016/j.bjps.2018.12.041
Mohan AT, Rammos CK, Akhavan AA, Martinez J, Wu PS, Moran SL et al (2016) Evolving Concepts of Keystone Perforator Island Flaps (KPIF): Principles of Perforator Anatomy, Design Modifications, and Extended Clinical Applications. Plast Reconstr Surg 137:1909–1920. https://doi.org/10.1097/PRS.0000000000002228
Lo Torto F, Frattaroli JM, Kaciulyte J, Mori FLR, Troisi L, Ciudad P et al (2022) The keystone flap: A multicentric experience in elderly patients’ treatment. J Plast Reconstr Aesthetic Surg 75:226–239. https://doi.org/10.1016/j.bjps.2021.08.043
Bhat S (2013) Keystone flaps in coloured skin: Flap technology for the masses? Indian J Plast Surg 46:36. https://doi.org/10.4103/0970-0358.113705
Yoon CS, Kim S, Il, Kim H, Kim KN (2017) Keystone-Designed Perforator Island Flaps for the Coverage of Traumatic Pretibial Defects in Patients With Comorbidities. Int J Low Extrem Wounds 16:302–309. https://doi.org/10.1177/1534734617740971
Chaput B, de Bonnecaze G, Lopez R, Benjamin V, Garrido I, Grolleau JL (2014) Modified Keystone Island Flap Design for Lateral Nasal Defect. Plast Reconstr Surg Glob Open 2:e213. https://doi.org/10.1097/GOX.0000000000000143
Formentin C, de Andrade EJ, Matias LG, Joaquim AF, Tedeschi H, Raposo-Amaral CE et al (2019) Using the keystone design perforator island flap in large myelomeningocele closure. Neurosurg Focus 47:E19. https://doi.org/10.3171/2019.7.FOCUS19383
Behan F (2018) Keystone perforator island flap: a clinical summary of 28 melanoma cases. Australasian J Plast Surg 1:45–50. https://doi.org/10.34239/ajops.v1i1.66
Penington T (2013) Science and the keystone flap. ANZ J Surg 83. https://doi.org/10.1111/ans.12290
Behan F, EVOLUTION OF THE FASCIOCUTANEOUS ISLAND FLAP LEADING TO THE KEYSTONE FLAP, PRINCIPLE IN LOWER LIMB RECONSTRUCTION (2008) ANZ J Surg 78:116–117. https://doi.org/10.1111/j.1445-2197.2007.04382.x
Rao AL, OF CLINICAL AND DIAGNOSTIC RESEARCH (2015) Keystone Flap: Versatile Flap for Reconstruction of Limb Defects. JOURNAL. https://doi.org/10.7860/JCDR/2015/12595.5631
Dobbs TD, Jovic TH, Jessop ZM, Kyle A, Hutchings HA, Whitaker IS (2018) Objective and Patient-reported Assessments of Skin Grafts and Keystone Flaps—A Pilot Retrospective Cohort Study. Plast Reconstr Surg Glob Open 6:e2024. https://doi.org/10.1097/GOX.0000000000002024
Yoon CS, Kim HB, Kim YK, Kim H, Kim KN (2019) 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. Medicine 98:e14167. https://doi.org/10.1097/MD.0000000000014167
Breiting LB, Venzo A, Dahlstrøm K (2009) [Keystone flap for reconstruction of skin defects]. Ugeskr Laeger 171:3702–3704

The authors declare no competing interests.

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Utility and Outcomes of the Keystone Perforator Island Flap for the Reconstruction of Various Anatomical Locations: A Prospective Study

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Abstract

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Background

Methods

Results

Aesthetic outcomes according to the POSAS

Patient Scar Assessment Scale (PSAS)

Observer scar assessment (OSAS)

Correlation between OSAS and PSAS

Presentation of some cases

Discussion

Conclusion

Abbreviations

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References

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