Pilot Study: Application of Lateralized Z-plasty in Pilonidal Sinus Defect Closure

Abstract

Background:

Pilonidal sinus (PS) is a chronic condition primarily affecting young adult men and characterized by recurrent abscess formation, discharge, and significant physical and psychosocial impacts. Traditional surgical methods, including basic Z-plasty, often fail to adequately address horizontal tension, leading to high recurrence and complication rates. This pilot study evaluated the efficacy of lateralized Z-plasty (LZP) for reducing horizontal wound tension and improving postoperative outcomes.

Methods:

We conducted a retrospective review of patients presenting with sacrococcygeal PS who underwent LZP repair at our hospital. A 2-stage surgical approach involving precise sinus excision followed by reconstruction with LZP was used. The flap design incorporated a central limb oriented laterally, creating triangular flaps that were transposed to reduce tension. The outcomes assessed included complications, recurrence, and patient satisfaction.

Results:

Between September 2023 and March 2025, 14 consecutive patients who underwent 15 LZP procedures were included in this study. No cases of flap necrosis, hematoma, seroma, or infection were observed. The mean hospital stay was 14.1 days (range, 9–22 d), with a mean follow-up of 6.2 months (range, 2–18 mo). One patient experienced delayed wound healing, and 1 experienced recurrence, which was managed with contralateral LZP. All patients expressed satisfaction with their postoperative appearance.

Conclusions:

The modified LZP technique shows promise as an effective alternative for PS treatment, offering reduced complications and improved functional and aesthetic outcomes, with potential for further optimization.

Takeaways

Question: Is lateralized Z-plasty (LZP) an effective modification for pilonidal sinus repair that improves outcomes by addressing the limitations of traditional flap techniques?

Findings: This retrospective study included 14 patients with pilonidal sinus who underwent a 2-stage procedure with LZP repair. The approach achieved complete flap survival, minimal complications, and only 1 recurrence, suggesting effective horizontal tension relief and reliable wound healing.

Meaning: LZP offers a promising alternative to traditional techniques, aiming to improve outcomes by reducing horizontal wound tension and minimizing recurrence and postoperative complications.

INTRODUCTION

Pilonidal sinus (PS) is a chronic infectious condition predominantly affecting young adults. Recurrent acute abscess formation and discharge cause significant physical discomfort and a psychosocial burden on patients.^1,2 Key factors contributing to PS include excessive body hair, deep gluteal clefts, and prolonged sedentary behavior.² Complete excision of the sinus tract and tension-free repair of secondary gluteal cleft defects are essential for successful surgical treatment.³ Despite various flap techniques, including basic Z-plasty (ZP), rhomboid flaps, Karydakis flaps, and V–Y advancement flaps, postoperative recurrence and complication rates remain unsatisfactory.^4,5 The lack of an ideal surgical technique makes PS treatment challenging for surgeons.

ZP is one of the most extensively used local flap techniques in plastic and reconstructive surgery.⁶ Although basic ZP has been used in PS treatment for decades, recurrence and complication rates remain suboptimal despite its documented effectiveness.^7–10 Basic ZP involves positioning the sinus wound along the central limb of the Z (Figs. 1A, B).⁸ However, this approach extends the wound vertically and relieves vertical tension but fails to address horizontal tissue tension theoretically, which plays a critical role in PS development and recurrence.¹¹ Thus, we hypothesize that a horizontally oriented, laterally directed ZP (Figs. 1C, D) may ameliorate horizontal wound tension, thereby reducing postoperative complications and recurrence. This pilot study evaluated the applicability, advantages, and limitations of lateralized ZP (LZP) based on our experience in repairing PS defects.

Fig. 1.

Comaprsion of basic Z-plasty and LZP. Basic Z-plasty (A, B) and LZP (C, D).

METHODS

We retrospectively reviewed all patients who underwent LZP repair for sacrococcygeal PS at our institution between September 2023 and March 2025. The same team performed all procedures. Patient demographics, body mass index, diagnoses, and outcome data—including flap size, surgery duration, drainage removal time, hospital stay, postoperative complications, and recurrence—were collected. This study was approved by our institutional ethics committee (approval number 2024KT608) and adhered to the 1975 Declaration of Helsinki. All patients provided written informed consent.

Surgical Technique

A 2-stage surgical approach was used. In the first stage, the sinus tract was precisely excised, and a closed vacuum drainage device was placed to temporarily close the wound and reduce the bacterial load. Bacterial cultures of the sinus tissue were obtained, whereas empirical antibiotic therapy was adjusted according to the culture results. The second stage, a reconstructive procedure performed 3–7 days later, involved LZP repair.

Dye-marked Sinus Removal

Preoperative preparations included bowel management and hair removal from the surgical site. Spinal anesthesia was administered, and the patients were positioned prone. After routine sterilization and draping, methylene blue dye was injected through the external sinus openings (skin pits) to delineate the sinus tract for precise excision. The sinus tract was unroofed by making an incision along the stained path with a scalpel, whereas the stained tissues were carefully excised using a monopolar electrocautery. Hemostasis was meticulously achieved, and the wound was irrigated with saline and hydrogen peroxide. The wound created by removing the sinus tract typically appears as a cavity with a wide base and a vase-shaped cross-section (Fig. 2). Negative pressure wound therapy (NPWT) dressing (Neptuno II NPWT System, Waston Medical Corporation, Changzhou, China) was applied to the wound to provide a continuous negative pressure of 125 mm Hg (although other pressures were available).

Fig. 2.

The defect after initial PS removal.

Reconstruction Using LZP

The second-stage repair procedure was performed 3–7 days after the initial sinus excision. The preoperative preparation, anesthesia, and positioning were identical to those in the first stage. Before flap design, additional debridement was performed, including excising a 2-mm wound margin and refreshing the wound base by removing all nonviable, chronically inflamed, or granulation tissue. The longitudinal wound in the gluteal cleft was designed as one of the peripheral limbs of the Z, with the central limb placed on 1 buttock and the 2 intersecting limbs at the cephalic apex of the wound at a 45–60 degree angle. The location of the other peripheral limb was subsequently identified, ensuring that all 3 limbs were of identical length, thus creating 2 equal-sized, triangle-shaped flaps (f1 and f2 in Figures 1C, D). The proximally based triangular flap (f1) was ultimately transposed over the midline defect in the gluteal cleft, whereas f2 covered the donor defect of f1 (Fig. 3).

Fig. 3.

Key steps in LZP. A, Flap elevation. B and C, Flaps before and after transposing.

The incision lines were marked, and a no. 11 scalpel was used to make the skin incisions. A monopolar electrocautery was used to cut through the subcutaneous fat down to the gluteus maximus fascia. Care was taken to bevel the incision outward for f1 by incorporating additional subcutaneous fat to effectively fill the deep defect. Both f1 and f2 flaps were elevated in the subfascial plane, forming adipo-fascio-cutaneous flaps. Temporarily interrupted sutures were placed to anchor the fascia to the dermis to prevent shearing between the fascia and skin paddle. After thorough hemostasis, the flaps were transposed and sutured in layers under minimal tension, with a vacuum drainage tube placed beneath the flaps. Standard surgical dressings were applied.

Postoperative Management

The dressings were changed every 2 days, and the drainage tube was removed when the output was 5 mL or less per 24 hours. The sutures were removed 2 weeks postoperatively. A low-residue diet was recommended to minimize bowel movements, and patients were advised to avoid bending, sitting, and engaging in similar activities for at least 2 weeks postoperatively.

REPRESENTATIVE CASE

A 15-year-old boy was referred to our department for the treatment of PS in the sacrococcygeal region. The primary complaint was recurrent purulent discharge from the external sinus (Fig. 4A). Following precise excision of the sinus (Fig. 4B), the resulting secondary defect measured approximately 5 × 4 cm (Fig. 4C). A closed vacuum drainage device was used for temporary wound coverage (Fig. 4D). LZP reconstruction was performed 4 days later. After further debridement, an LZP flap was created on the left buttock to cover the defect (Fig. 4E). Two triangular flaps were elevated at the level of the gluteus maximus fascia and transposed to achieve complete wound coverage (Fig. 4F). The incision was sutured in layers, and a vacuum drainage tube was placed beneath the flaps (Fig. 4G). The wound healed successfully, and the sutures were removed 2 weeks postoperatively. Follow-up at 2 months revealed satisfactory results (Fig. 4H).

Fig. 4.

Repensentative case. A, Preoperative picture showing the skin pits in the sacrococcygeal region. B, The sinus that was removed. C, The defect after dye-marked sinus removal. D, NPWT dressing was applied. E, Intraoperative picture of LZP flap design. F, Two triangular flaps were transposed. G, Postoperative image at the immediate end of the surgery. H, Postoperative image at 2-month follow-up.

RESULTS

Overall, 14 consecutive patients (11 men and 3 women) underwent 15 LZP procedures for sacrococcygeal PS. The patients had a mean age of 21.5 years (range, 12–33 y) and a mean body mass index of 27.5 kg/m² (range, 20.5–37 kg/m²) (Table 1). Of the cases included, 5 presented with acute infections and 5 had positive bacterial cultures, with the largest defect measuring as much as 8 × 7 cm. All but 1 recurrent case underwent 2-stage procedures with an interval of 3–7 days (mean 4.5 d) between procedures. The average operative time for the LZP procedure was 86.7 minutes (range, 55–135 min). The flap sizes ranged from 4 × 3 cm to 8 × 7 cm. Drainage tubes were removed within 2–8 days (mean 4 d) postoperatively, whereas hospital stays ranged from 9 to 22 days (mean 14.1 d). The follow-up duration was 2–18 months (mean 6.2 mo). All flaps survived without local or complete necrosis. No hematomas, seromas, or wound infections were observed. One patient experienced delayed wound healing due to inappropriate postoperative activities, which resolved within 3 weeks of conservative dressing management. There was a recurrence 2 months postoperatively, and it was successfully managed with contralateral LZP repair. No significant deformities, gait abnormalities, or sensory disturbances were reported, and all patients were satisfied with their postoperative appearance.

Table 1.

Patients’ Demographics and Case Characteristics

Patients	Sex	Age, y	BMI, kg/m2	Flap (f1) Size, cm	Operation Time, min	Drain Removal	In-hospital Stay, d	Complications	Follow-up, mo
1	M	28	27.8	6 × 4	80	POD 3	13	None	18
2	M	33	29.3	5 × 4	55	POD 4	13	None	14
3	M	25	23.8	5 × 4	85	POD 3	18	None	9
4	M	16	30.6	5 × 4	60	POD 5	16	None	8
5	F	15	26.3	4 × 3	80	POD 3	9	Delayed wound healing	6
6*	M	18	29.8	5 × 4	90	POD 2	14	Recurrence	2
	M	18	29.8	4 × 3	90	POD 3	10	None	5
7	F	28	26.0	5 × 4	85	POD 4	13	None	7
8	M	19	26.2	5 × 4	85	POD 4	12	None	6
9	M	12	33.3	5 × 4	95	POD 3	22	None	5
10	M	15	26.3	4 × 4	90	POD 5	14	None	3
11	M	33	22.8	5 × 4	85	POD 5	13	None	3
12	M	16	37	6 × 4	135	POD3	10	None	3
13	F	23	25.5	7 × 6	85	POD8	22	None	2
14	M	20	20.5	8 × 7	100	POD5	13	None	2
Average	—	21.5	27.5	4.8 × 4.2	86.7	4	14.1	—	6.2

^*Recurrent case.

BMI, body mass index; POD, postoperative day.

DISCUSSION

The optimal treatment of PS has been controversial for over a century.¹² Although numerous treatment methods have been proposed, surgery remains the primary treatment. Techniques, including basic ZP, rhomboid flaps, Karydakis flaps (Bascom flaps), and V–Y advancement flaps, have been extensively used. However, the high incidence of postoperative complications—including infection, wound dehiscence, delayed healing, and recurrence—poses significant challenges.^13,14 Our modification of the traditional ZP to LZP may help address these issues by alleviating horizontal tissue tension. Using a well-vascularized adipo-fascio-cutaneous triangular flap to fill the defect facilitates deep defect repair and reduces complications. To the best of our knowledge, LZP has not been reported in the literature and offers a new option for PS surgery.

Prolonged sitting is a critical factor in PS development, causing high stretching tension in the horizontal direction.¹¹ It is widely accepted that tension relief is crucial for successful wound healing. Treatment methods such as excision with primary midline closure, off-midline primary closure (Karydakis, Bascom cleft lift), and traditional ZP fail to alleviate but rather increase horizontal tension. In contrast to traditional vertical ZP, LZP provides superior horizontal tension reduction, which is a major cause of poor postoperative healing in patients with PS. Kaneyuku et al¹¹ achieved promising results in repairing PS defects by releasing horizontal tension using superior gluteal artery perforator flaps to fill the midline gluteal defects. However, perforator flap surgery has certain limitations, including a steep learning curve and the need for meticulous intramuscular dissection of the pedicle, which carries the risk of damaging the perforator vessels. Unlike rhomboid flaps or other full-thickness flap techniques, our technique avoids unnecessary wide tissue excisions, which can increase donor site tension and the risk of infection,¹⁵ hematoma, and seroma.³ Previous studies have indicated substantial variation in recurrence rates across different techniques. However, a recent systematic review from Ida-Marie et al¹⁶ found no significant differences in recurrence rates between the different flap operations. In our study, there was only 1 case of recurrence, which occurred in a patient with a laterally displaced sinus at the apex of the midline triangular flap at the gluteal cleft (Fig. 5A). A subsequent revision surgery using LZP on the contralateral buttock resulted in favorable postoperative outcomes (Fig. 5B). This case underscores the importance of minimizing horizontal tension at the midline to promote proper wound healing and reduce the risk of recurrence. It also highlights an added advantage of LZP compared with traditional ZP—using tissue from only 1 side of the buttock, it preserves the contralateral side for potential secondary repair if needed.

Fig. 5.

Recurrent case. A, A recurrent PS was noted at the apex of the f1 triangular flap. B, Postoperative images at the immediate end of the revision surgery using a contralateral LZP flap.

Although PS wounds are relatively concealed, hypertrophic scarring and gluteal cleft deformation can negatively affect cosmetic outcomes. Striking a balance between reducing recurrence rates and achieving aesthetically favorable results is vital for patient satisfaction.^17,18 Dissatisfaction rates following rhomboid flap repair range from 5.4% to 20% in the literature.^19–21 In our study, none of the patients reported dissatisfaction with their postoperative appearance, as they were shown photographs of their surgical sites at the final follow-up and asked verbally about their aesthetic satisfaction. Our approach minimizes unnecessary excision of surrounding tissues, resulting in less distortion and wound tension than rhomboid flaps. However, the laterally oriented incision line in the LZP may have a minor impact on the cosmetic outcomes.²²

Infection rates following traditional ZP for PS reconstruction range from 5.88% to 7.1%.^7,23 In our study, no surgical site infections were observed. This can be attributed to our 2-stage approach, where the initial procedure involved complete sinus tract excision and the use of NPWT to decrease bacterial colonization and increase localized blood flow (flux) before flap reconstruction.²⁴ However, this 2-stage surgical approach can indeed increase patient discomfort, prolong hospitalization, and add to the financial burden. For patients with less symptomatic or quiescent disease, a single-stage excision and flap repair may be sufficient and more appropriate. A prospective randomized trial conducted by Hannan et al²⁵ compared the effects of NPWT and secondary intention healing, demonstrating no significant differences in healing time, disease recurrence, or wound infection rates. However, we observed a significant reduction in the wound size after the initial surgery with the application of NPWT, especially in PS cases with acute abscess, which facilitated the secondary surgical repair. Hematoma and seroma were absent in these patients. During flap preparation, beveled incisions were made to incorporate additional subcutaneous fat, effectively fill the deep cavity, and obliterate dead space. Furthermore, the dense network of subcutaneous ligaments in the buttock region provides a natural resistance to shearing. However, temporary sutures are advised to secure the fascia to the dermis, further minimizing tissue separation.

Dedicated wound care and proper behavioral management during the postoperative period are essential for successful outcomes. Delayed wound healing was observed in one of our patients due to improper ambulation; however, the wound eventually healed after 3 weeks of conservative dressing changes. We recommend avoiding bending and maintaining a straight posture for at least 2 weeks postoperatively while minimizing sedentary time. Preoperative bowel preparation and a postoperative low-residue diet were advised to reduce the adverse effects of bowel movements on wound healing. An effective treatment strategy for PS involves meticulous preoperative planning, precise intraoperative execution, appropriate postoperative care, and strict management of patient behavior.

The primary limitations of LZP include its inapplicability in cases with lateral sinus tracts, multiple branches, extensive abscesses, and recurrent cases involving significant tissue loss. In such cases, a rhomboid flap or its modifications may be more suitable. Additionally, LZP involves a learning curve that requires surgeons to acquire sufficient expertise for effective implementation. Our study also had some limitations, including a small sample size, a lack of a control group, and a relatively short follow-up period. Although the initial results suggest potential advantages over other surgical methods, long-term controlled studies are warranted to validate these findings.

CONCLUSIONS

The modified LZP technique shows substantial promise in reducing postoperative complications, including infection, wound dehiscence, and recurrence. Our findings indicate that LZP is an effective and viable alternative for managing PS, offering promising outcomes in both functional and aesthetic aspects. Although the number of cases remains limited, the theoretical benefits of this procedure have been confirmed by our clinical experience, indicating the need for further exploration and optimization of this technique.

DISCLOSURE

The authors have no financial interest to declare in relation to the content of this article.