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ORIGINAL ARTICLE
Year : 2022 | Volume
: 30
| Issue : 2 | Page : 38-43
Novel use of Pedicled Medial Sural Artery Perforator flap for Post Burn Knee Contractures
Mukesh Kumar Sharma, Vaddi Suman Babu, BS Harini, Manoj Kumar Jha, Ashok Daram Reddy
Department of Burns, Plastic and Maxillofacial Surgery, ABVIMS and Dr. RML Hospital, New Delhi, India
Correspondence Address:
Dr. Vaddi Suman Babu
Department of Burns and Plastic Surgery, ABVIMS and Dr. RML Hospital, New Delhi
India
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/tjps.tjps_39_21
Background: Postburn flexion contractures of the knee may arise even with adequate treatment of the burn injury. Pedicled medial sural artery perforator (MSAP) flap has been described for the reconstruction of defects of the knee and proximal third of the leg. Its use in the management of postburn contracture release is sparse. We are presenting the use of a medial sural artery pedicled flap for the reconstruction following postburn knee contracture release. Materials and Methods: This study included six patients with postburn unstable scars and a mild degree of knee contractures who underwent release of the contracture and coverage using MSAP pedicled flap. The results in terms of flap size, recurrence, complications, functional outcome, and cosmesis were assessed. Results: The flap size ranged from 7 cm × 6 cm to 13 cm × 7 cm with a mean pedicle length of 9.41 cm. All six flaps survived without any complications with a satisfactory outcome. The patients were followed up for 6–18 months. There was no recurrence of contracture without any restriction of knee joint mobility. Conclusion: MSAP flap is a reliable flap and should be considered for the management of postburn knee contracture of grade 2 and grade 3 contractures, as it provides optimum and ideal coverage with fewer chances of recurrence.
Keywords: Medial sural artery perforator, pedicled flap, postburn knee contracture
Knee flexion contracture is a frequent sequela following full-thickness burns around the knee joint, resulting in abnormal gait secondary to reduced range of motion and impaired lower extremity function.[1] These scars are prone to ulceration and keloid formation[2] and treatment usually requires radical excision/incision to completely release the scar tissue followed by reconstruction. The most commonly used reconstructive method is the incisional release of contracture and skin grafting[3] Other modalities of the surgical reconstruction described in the literature include local flaps, regional pedicled flaps, free flaps, and gradual external fixation distraction depending on the size of the defect.[1],[2]
Medial sural artery perforator (MSAP) flap is a thin, pliable flap and provides durable skin cover, which makes it a good option for reconstruction following the release of knee contracture. These flaps can be safely used even when the donor site of the flap has sustained 1st degree and 2nd degree superficial burns.[4] This article summarizes our experience with this versatile MSAP island flap for reconstruction of postburn knee flexion contracture release defects in terms of flap size, recurrence, complications, functional outcome, and cosmesis.
Materials and MethodsBetween January 2018 and January 2020, six patients with Grade 2 and Grade 3 postburn knee contracture and unstable scars over the medial or lateral edge of the knee region were included. All of them had a history of conservative management with dressings and had inadequate splinting during the postburn period, and none of them received any surgical procedure. The patient data are summarized in [Table 1]. The contractures were initially assessed for the site of contracture, degree of contracture, functional deficit, quality of the scar, surrounding tissue, and donor site, and an apparent defect was measured.
Indications for the flap coverage were
Patients with Grade 2 and Grade 3 of postburn contracture and unstable scarsExposure of hamstring tendons and neurovascular structures following the release of the contractureEsthetic considerations.Prerequisites
Presence of donor tissue without any previous scarsIf a burnt scar is present, the scar should be mature and supple.Surgical technique
Preoperatively, handheld Doppler was used to locating the position of perforators carefully along the line joining the mid popliteal crease and the medial malleolus. After perforator identification, flap markings were done with the perforator placed either in the middle or midline proximally [Figure 1].
The operation was performed under a pneumatic tourniquet without limb exsanguination and under loop magnification. Under spinal anesthesia, the patient was placed in a prone position with the knee in extension or supine with hip and knee flexed and externally rotated. The contractures were completely released, and unstable and hypertrophic scars were excised. Depending on the size of the defect that resulted after release, the flap markings were modified. A medial incision of the flaps was given first to include skin, subcutaneous tissue, and the deep fascia. Once the sizeable perforators were identified, then the lateral margin of the flap was incised. Then de-roofing of the perforator was done in the gastrocnemius muscle with careful ligation of the muscular branches was performed under loop magnification. Dissection of the pedicle continued till the flap reach is achieved without any stretch over the pedicle. The bridge skin between the donor and recipient site was incised in all cases for the passage of the pedicle. The good dermal bleed of the flap was checked, and the vascularity was confirmed after the release of the tourniquet, and the flap was transferred to the defect and the final inset was done using nonabsorbable sutures. The donor site was grafted in all our cases. In three cases, a split-thickness graft was used on one side of the flap in cases of larger defects.
Postoperatively, the patients were placed in a prone position with a pop slab for knee extension and immobilized for 2 weeks. No anticoagulants were given and gradual passive and active mobilization of the knee joint started after 2 weeks. Postoperatively, all patients were advised massage, pressure garments, and silicone gel sheet for the calf and thigh donor sites. All the patients were followed for 6–18 months.
ResultsThermal burns are the most common cause of etiology in our series. The mean age of the patients was 35.1 years. One patient was female out of six patients. The degree of contracture ranged from 10° to 20°. The flap size ranged from 7 cm × 6 cm to 13 cm × 7 cm and the mean pedicle length of 9.41 cm. Five flaps were based on a single perforator and one flap was based on two perforators. The average duration of the operation was 2.5 h. All patients had an uneventful postoperative course. All the flaps survived completely and settled well [[Figure 2]: Case 1 and [Figure 3]: Case 5]. The graft take over the donor area was excellent without any graft loss, and the grafted areas healed well without any areas of hypertrophy. The mean duration of follow-up was 11.5 months and showed good functional and cosmetic results. The patient data and surgical outcomes are listed in [Table. 1].
Figure 2: Case 1. (a) Unstable scar over the left knee lateral region. (b) Intraoperative picture showing the medial sural artery perforator flap along with the pedicle. (c and d) Well-settled flap and the skin graft over the donor site at 6 months' follow-up
Figure 3: Case 5. (a) Right knee contracture over the lateral region. (b) Intraoperative markings of the flap. (c and d) Intraoperative picture showing dissected flap along with the pedicle and its reach to the recipient site. (e) Intraoperative picture showing the inset of the flap and skin graft over the donor site. (f) Well-settled flap and donor area at 4 months' follow-upIllustrative cases
Case 1
A 45-year-male presented with postburn contracture of the left knee region on the lateral aspect with an unstable scar. He had a history of flame burns 4 years ago. He underwent contracture release with excision of the unstable scar and the defect was reconstructed with a pedicled MSAP flap [Figure 2].
Case 5
A 26-year-old male presented with postburn contracture of the right knee region. He sustained flame burns 2 years ago which were managed conservatively and healed with contracture. He underwent contracture release and reconstructed with pedicled MSAP flap and split-thickness skin grafting [Figure 3].
DiscussionMost of the knee contracture involves either the medial and lateral area of the popliteal region, and the central area is usually spared, and the treatment plan depends on the severity of knee contracture.[5][Table 2] Release of postburn contractures of the knee usually results in large defects with the exposure of tendons and sometimes neurovascular structures in the popliteal region. McCauley and Asuku[5] reported that incisional or excisional release and skin grafting is frequently the first line of therapy with excellent long-term results. However, in practice, recurrence is the most common complication after skin grafting because of graft contraction and poor compliance with the usage of postoperative splints. In this scenario, flap coverage is the best option following the release of postburn contractures since, to a large extent, it prevents recurrence and has a much better aesthetic outcome.[6] Flap coverage brings well-vascularized tissue into the defect, thereby improving healing, prevents the formation of re-contractures, and allows early ambulation in the postoperative period.[7]
The most common local flap is Z plasty and its various modifications.[8],[9],[10] Buis et al.[11] reported that a conventional Z-plasty on postburn scar tissue often leads to varying degrees of necrosis of the tips of the transposed flaps. Moreover, they are not indicated for broad scars and do not provide complete coverage of the raw area. Other local flaps include V-Y plasty and its variations.[12],[13] Efficacy of V-Y procedure in burn scars is less, as the flaps have restricted mobility in the burnt skin.[14] Other options and techniques include Z-lengthening of tendons and gastrocnemius muscle flap,[15] distally-based fasciocutaneous thigh flap,[16] proximally-based sural flap,[17] posterior calf fascial flap,[18] reverse anterolateral thigh,[19] Ilizarov technique,[20] combined Ilizarov technique and free flap for severe recurrent flexion contracture release.[21]
Traditional fasciocutaneous flaps have limited mobility and difficulty in reach and often suffer distal ischemia and are not usually done for the knee region. Gastrocnemius muscle is the most common regional muscle flap used for knee defects. Muscle flaps require sacrificing the muscle, and it can lead to some weakness, which gets compensated gradually. Perforator flaps have unique advantages, and their use for reconstruction of knee defects has been described previously.[19],[22],[23] They cause less donor site morbidity and have better reach when islanded. However, they are not frequently used because they require expertise and require tedious microvascular dissection, and also the perforator flaps are less described for the knee region.
The MSAP island flap was first described by Cavadas et al. in 2001.[24] They reported the anatomy of the MSAP flap in 10 cadaver dissections and clinical applications in six clinical cases. Hillock conducted an anatomical study of the musculocutaneous perforators from the gastrocnemius muscle on 10 fresh cadavers.[25] Later on, the anatomical study was performed and reported by various authors.[26],[27],[28],[29] Medial sural artery arises from the popliteal artery at, slightly above, the level of the joint line and supplies the medial gastrocnemius muscle. It supplies the overlying skin through perforators. This artery has a mean of 2.2 perforators and arises at a range of 9–18 cm from the popliteal crease.[24] Its use as a pedicled flap for the reconstruction of upper one-third and knee leg defects successfully has been reported by various authors.[30],[31] The use of MSAP flap as a free flap has been reported for the reconstruction of head and neck, hand, and leg defects.[32],[33],[34],[35]
Kim et al.[27] conducted an anatomical study on 40 Legs in 20 cadavers. They reported the location of the first perforator and second perforator at a mean distance of 9.68 ± 1.08 cm and15.04 ± 1.79 cm distance from the midpoint of the popliteal crease, respectively. They proposed a new design of the flap to include a 2-radius circle at an 8 cm distance from the popliteal crease over the imaginary line from the mid popliteal crease to the medial malleolus with hip abducted and knee in 90° flexion. This 2 cm radius circle corresponded with the location of the proximal perforator in their anatomical study. They also reported a series of 21 clinical cases using MSAP flap including, 18 free flaps and 3 pedicled flaps with a maximum flap size of 14 cm × 14 cm, and reported good outcomes in all patients except one partial necrosis in a diabetic patient.
Wong et al.[28] also did an anatomical study in 10 fresh adult cadavers. An average of 4.4 perforators was found with at least one major perforator with a mean of 2 major perforators. The medial sural artery divides into medial ad lateral branches at a distance of 3–6 cm from the popliteal crease. The perforators were consistently arranged in two vertical rows corresponding to the branches. The perforators were more and larger in the lateral row, closer to the posterior midline ~2 cm away. They reported a consistent larger perforator at 10 cm ± 2 cm from the popliteal crease and 2 cm ± 0.5 cm from the posterior midline. This finding is consistent with previous studies.[24],[25],[27],[29] Based on the anatomical study, they successfully used the flap in five clinical cases.
Umemoto et al.[30] reported the sural artery perforator flap for the coverage of defects of the tibia and knee region in four patients. All the flaps survived without any complications. The maximum size was 10 cm × 20 cm. A medial perforator was used in three patients, and a lateral sural artery perforator was used in one patient. In this series, they used a 4 cm × 6 cm flap for the burn contracture release in one patient with direct closure of the donor site. In our series, we used only the medial sural artery in all the cases with a maximum flap dimension of 13 cm × 7 cm.
Kim et al.[4] described medial sural perforator plus flap in the reconstruction of postburn knee contractures using the burned calfskin. They used pedicled MSAP flap in three patients and MSAP plus flap in nine patients with a maximum flap dimension of 15 cm × 20 cm. They included lesser saphaneous vein, sural nerve, and associated arteries along the lesser saphenous vein and sural nerve. They proposed that MSAP plus flap has augmented arterial supply and venous drainage of the skin paddle so that large flaps can be raised safely from the burned calfskin. In our study, we used only the MSAP pedicle in all our cases and, one case had a pliable burnt scar over the calf region. We did not encounter any flap necrosis.
Tee et al.[31] have described the retrograde flow pedicled flap for the coverage of middle third leg defects. They reported retrospective case series of 11 antegrade pedicled MSAP flaps and 3 retrograde flow pedicled MSAP flaps. All the antegrade flaps survived completely without any complications. All three retrograde flaps had complications. One partial flap loss, one had a superficial epidermal loss, and one complete flap loss. In our series, all the flaps were antegrade flaps, as the defect is at the popliteal region.
We observed that one of the venae comitantes is relatively thick, and we did not have any venous complications in our series. This finding has been reported by few authors.[27] We encountered a very thin perforator in one flap, and the same flap had an episode of arterial spasm postoperatively and it got relieved spontaneously, and the flap survived completely. We raised the flap based on a single perforator in five patients and 2 perforators in one patient. We used the proximal first perforator in four patients and second perforator in one patient and both first and second perforators in one patient. The mean length of the pedicle was 9.41 cm. This finding is similar to previous studies.[4],[28] No flap-related complications were encountered in our series. None of the patients required additional flaps or any debulking procedures. No patient complained of any gastrocnemius muscle weakness, and the contraction of the muscle was normal in all the patients postoperatively. No disturbances in knee mobility and strength were noticed. All the patients were satisfied with the cosmesis and improved range of motion.
MSAP flap has many advantages. It is an ideal locoregional flap for knee, distal thigh, and upper leg defect reconstruction, it can be harvested either in supine or prone position under spinal or epidural anesthesia, it is a relatively thin and pliable flap and does not require flap thinning even in obese patients, it's longer vascular pedicle suits the easy reach to the recipient area, muscle-sparing as the motor nerve to the gastrocnemius enters at the proximal one third, and it is usually spared, tourniquet use facilitates the bloodless field and the ease of harvest provides good color and texture match, allows early mobilization and ideal flap for small and medium-size defects.
The disadvantages of this flap include tedious microsurgical dissection of the perforator in the muscle, scar over the calf region, which is not acceptable, especially in the case of young females, variable location of major perforators, and relatively diminutive perforators and inadequate to cover large size defects.
ConclusionMSAP based pedicled flap is a reliable flap for the reconstruction following the release of Grade 2 and Grade 3 type of postburn flexion contracture of the knee. It provides thin and pliable tissues for reconstruction, allows early mobilization of the patient, and produces satisfactory cosmesis without causing any functional deficit in the donor area, and also prevents the recurrence of knee contracture.
Informed consent
Informed consent was obtained from each patient.
Declaration of patient consent
The authors declare that they had obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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