Chir Plastica (1986) 8 : 215-221 Chiru..rgia plastlca 9 Springer-Verlag 1986
The Gluteus Maximus Musculocutaneous Flap as Bilateral V - Y Sliding Flap or as Pendulum Flap for Closure of Sacral and Ischial Pressure Sores
R. van Twisk and J .M.H.M. Borghouts Department of Plastic and Reconstructive Surgery, St. Radboud Ziekenhuis, University of Nijmegen, The Netherlands
Summary. Eight V-Y and fourteen pendulum gluteus maximus myocu- taneous flaps have been used in eighteen patients for closure of sacral and ischial pressure sores. The patients have been followed-up for be- tween 3 and 36 months and there was only one recurrence in a patient who had had a bilateral pendulum flap. There has been no functional impairment in the ambulant patients.
Key words: Sacral pressure sore - Ischial pressure sore - Gluteus maxi- mus myocutaneous flaps - V-Y musculocutaneous flap - Pendulum flap.
Despite attempts to prevent and treat bedsores conservatively, some patients will require surgical closure of their sores. The operative management of such defects must be aimed at removing all scar tissue in and around the pressure sore and replacing it with healthy, well vascularised skin and subcu- taneous tissue. Pressure sores usually occur where the skin is directly overly- ing the bone, and the bulk of the transposed tissue must be sufficient to protect the skin from the shearing and pressure forces applied to it after the operation wound has healed.
The authors would like to present two methods for closing the sacral and the ischial pressure sore by utilizing musculocutaneous units, both based on the gluteus maximus muscle. The first is a bilateral V-Y flap for closure of sacral pressure sores and the second is a pendulum flap, for closure of ischial pressure sores.
Anatomical Basis for the V-Y and the Pendulum Myocutaneous Flap Based on the Gluteus Maximus Muscle (Fig. l)
The origin of the gluteus maximus muscle is the lateral surface of the sacrum, the os coccyx and the adjacent sacrotuberous ligament. The largest part
216 R. van Twisk and J.M.H.M. Borghouts
Fig. 1. Anatomy of the vascular supply of the gluteus maximus muscle
of its insertion is fascial and forms the ileotibial tract. The osseous insertion is on the gluteal tuberosity of the femur and the linea aspera. The trochan- teric bursae separate the gluteus muscle from the greater trochanter of the femur.
The blood supply to the skin and subcutaneous tissue of the buttock is derived from numerous perforating vessels from the gluteus maximus muscle, which, based on its vascular anatomy, can be divided into two parts. The blood supply of the cranial part comes from the superior gluteal artery, the largest branch of the internal iliac artery. It emerges above the superior border of the piriform muscle and divides into two branches, the superficial branch, which enters the under surface of the gluteus maximus muscle and a deep branch which is the main blood supply to the gluteus medius muscle.
The inferior part of the muscle is supplied by the inferior gluteal neu- rovascular pedicle, which emerges below the piriformis muscle at the lateral edge of the sacrotuberal ligament. One branch penetrates the deep surface of the gluteal muscle close to its origin. A second branch runs to the skin of the posterior thigh and is accompanied by the posterior femoral cutaneous nerve. It forms an entity that can be used as an axial pattern flap or even a free flap . Besides these two dominant pedicles, the muscle has a blood supply at its origin on the sacrum, which contains branches of the internal pudendal artery and branches entering near the linea aspera that form the cruciate anastomosis .
The Gluteus Maximus Musculocutaneous Flap 217
Fig. 2a, b. The V-Y flap (a). The gluteus maximus muscle is sutured in the midline. Next the V shaped skin islands are sutured and the donor defects are closed in a Y fashion, b Schematic representation of the procedure
An important factor in the use of the gluteus flaps in ambulatory patients is the fact that the entire muscle is innervated from the inferior gluteal nerve (L5, S1, $2). The superior gluteal nerve (L4, L5, $1) accompanies the superior gluteal pedicle and innervates the gluteus medius, gluteus mini- mus and tensor fascia lata muscles. The gluteus maximus is important for walking, climbing and one-legged support. The superior portion of this muscle is an abductor and stabilizer of the thigh and the inferior part assists in hip and leg extension and external rotation.
Operative Procedure of the Bilateral V-Y Flap (Fig. 2)
We have found it very useful to locate both vascular pedicles by means of the Doppler probe. During the operation the pressure sore is excised and bone prominences are removed. A V-shaped incision on both sides of the defect is then made. After the muscle is reached and incised, the dividing plane between the gluteus maximus and medius is dissected bluntly. This is best done by starting supero-laterally.
It is important to identify the piriformis muscle, as the superior gluteal vascular bundle emerges from its upper edge, about 3 or 4 cm below the iliac rest. After further mobilization of the superior and inferior border of the strip of muscle, the medial aspect is separated from the sacrum. Haemostasis should be carried out before the branches of the internal puden- dal vessels retract, as retro-peritoneal bleeding may cause a serious problem. In the ambulatory patient the muscular insertion should not be separated from the femur to preserve muscle function and it is important that the inferior pedicle is carefully preserved [9, 11].
In this way sufficient mobilization can be achieved to bring the muscle to the middle of the defect and to suture it to the muscle on the other side. The donor defect can be closed in a Y-form (Fig. 2b).
218 R. van Twisk and J.M.H.M. Borghouts
t luteusaximus S u o e r i o r p a r t G l u t M a x inferior part
Skin island ~ / / ~ , ~ ~ " \\ \~'~'~'~ ,i~ with abundant soft tissue ~ ~
~//~i~ Lined Aspera b
Fig. 3a, b. The pendulum plasty offers sufficient bulk with a small skin island to close the ischial defect (a). The photo shows the musculocutaneous unit before transposition into the defect, b Schematic representation of the gluteus maximus pendulum flap
Operative Procedure With the Pendulum Flap (Fig. 3)
A pressure sore in the ischial region is quite different from the sacral pressure sore. The skin defect is often small but quite often there is a considerable loss of subcutaneous tissue in the surroundings of the ischial bone. This means that at operation the design of the skin island can be small, just a few centimetres in diameter, but the subcutaneous tissue should be suffi- cient to replace the tissue over the ischium.
The Gluteus Maximus Musculocutaneous Flap 219
Preoperatively the inferior gluteal vascular bundle is located by means of the Doppler probe. The pressure sore is excised and the outer cortex of the bone, often the site of osteitis, is removed and the amount of soft tissue to be replaced is assessed. The localization of the skin island on the donor area is determined just distal to a line drawn between the greater trochanter and the os ischium. The skin island is incised and the subcutane- ous tissue is incised by beveling outward and downward preserving a large amount of soft tissue.
The gluteal muscle is incised near the linea aspera and then an incision parallel to the distal border of the gluteus muscle is made through the muscle, thus creating a stalk of parallel muscle fibers, acting as the axis of a pendulum (Fig. 3 b). The location of the inferior neurovascular bundle is identified and the muscle further mobilised. In the ambulatory patient, , however, no further mobilization superior to the neurovascular bundle is done to prevent damage to the inferior gluteal nerve. Next the skin island, subcutaneous fat and muscle are brought into the defect. The donor side can be closed primarily.
During the last three years we have treated 18 patients, whose ages ranged from 19 to 73 years with pressure sores in the sacral and the ischial regions. There were six post-traumatic paraplegics, nine spina bifida patients and three patients who had other neurological disorders. The treated defects ranged in diameter from five to ten centimetres for the sacral sore and from two to four centimetres for the ischial sore.
The subcutaneous tissue loss in the ischial sores was always quite large, often up to fifteen centimetres in diameter with undermining of the wound edges. Most of these patients had sores of long duration, ranging from four months to more than five years. Only one patient had never before been operated upon for a pressure sore, while the others had a history of all sorts of conservative treatment and numerous surgical procedures. In this group of patients the V-Y plasty was used eight times and the pendulum plasty was used fourteen times. Three patients had a bilateral pendulum flap and one had a combination of the V-Y plasty and the pendulum flap. In the postoperative period ranging from three months to three years, there were two recurrences in one patient treated by a pendulum plasty. The defects were closed by excision and suture. Within the group which had a pendulum plasty, a postoperative complication occurred in four cases, all in the donor area. One had a wound infection and subsequent wound dehiscence, which was treated conservatively; two had a wound haematoma and wound dehiscence. One of these wounds had to be closed by a rotation flap, but the others were treated conservatively and closed spontaneously. In the group with the pendulum plasty there were three ambulant patients; one had a bilateral pendulum plasty and plays competit ion table tennis, the others are walking with crutches. None had an impair- ment of mobility.
The merit of using the gluteus maximus muscle whether as muscle [1, 2, 13], as part of a musculocutaneous transposition flap , or as carrier of a skin island to close a pressure sore in the sacral and ischial region is well recognised. Musculocutaneous units are better than random flaps for the closure of contaminated pressure sores. Chang et al.  showed clearly that muscle and musculocutaneous flaps are more resistant to infec-
220 R. van Twisk and J.M.H.M. Borghouts
Fig. 4. The V-Y flap (1) and pendulum flap after (2) one year. Patient A
tion. Moreover, the musculocutaneous unit offers much more protection to the underlying bone due to a larger bulk of tissue. Transposition of skin and subcutaneous tissue only creates a similar situation of skin over bone, even when the prominences of the bone are removed. In these cases it is very likely that the pressure sore will re-occur . The use of muscle and a split-skin graft to close the defect is, in our opinion, not to be recom- mended. Notwithstanding the fact that good results have been reported, we feel that the quality of the healed split-skin is always inferior to a skin flap and the subcutaneous tissue of the musculocutaneous unit. This also applies to some of the gluteus maximus musculocutaneous flaps described in the literature , where the split-skin is used for the donor area. The unilateral V-Y sliding flap  and the rotation island flap  require more mobilization, and we think that it is easier to compromise the neurovascular pedicle by traction than in the bilateral V-Y flap [6, 12]. To our knowledge the pendulum flap has only recently been described by Ramirez et al.  as " the extended gluteus maximus myocutaneous flap". It differs from the V-Y or advancement flap in this region [7, 10] as it is a true transposition flap. Its advantage is that there is less scarring in the ischial region and the donor site lies in a non-pressure bearing area when the patient is in
The Gluteus Maximus Musculocutaneous Flap 221
a sitting position. The donor site morbidity of the pendulum flap is, however, troublesome. Better drainage and postoperative restriction of flexion in the hip would have prevented our complications. Two wound dehiscences were seen in the two ambulatory patients and one in a patient with spastic flexion contractures of both legs. The healing of these wounds, in a pressure-free area, was rapid in all cases, and the patients experienced little discomfort.
Both the V - Y and the pendulum flap can be used on the same patient (Pt.A. Fig. 4). This combination of procedures should perhaps be limited to the completely paraplegic patient, as there might be too much risk of damage to the inferior gluteal nerve.
Isolated use of the bilateral V - Y flap [6, 12] should never give an impair- ment of mobility. The fact that in the long term follow-up only two recur- rences occurred proves that both flaps are reliable and can save unneccessary procedures for the closure of pressure sores both in the paraplegic and the ambulatory patient.
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