The iliac bone or osteocutaneous transplant pedicled to the deep circumflex iliac artery

j. max.-fac. Surg. 11 (1983) J. max.-fac. Surg. 11 (1983) 195-200 © 1983 Georg Thieme Verlag Stuttgart • New York

The lliac Bone or Osteocutaneous Transplant Pedicled to the Deep Circumflex Iliac Artery I. A n a t o m i c a l and T e c h n i c a l C o n s i d e r a t i o n s Klaus Bitter and Tibor Danai Dept. of Maxillo-Facial Surgery (Head: Prof. Stellmach, M.D., D.D.S.), Free University of Berlin, W-Germany

Introduction The development and introduction of microsurgical vessel anastomosis has made possible completely new concepts of reconstructive surgery. These include soft tissue and bone replacement. The latter procedure has been in use for a long time as a free non-vessel-pedicled graft. Despite the fact that these methods were outlined a long time ago, the results were not satisfactory under certain circumstances. Because of this, microsurgery was welcomed as a means of transplanting even bone with a vessel pedicle, thus achieving maximum reparative capacity in the field of reconstruction. The iliac crest was as far as we know first used as a donor site for the maxillo-facial region by Lindemann during World War I. Because of the shape and relative bulk of this bone, it was generally accepted as the most favourable source of a graft. On the other hand, free bone transplantation may be subject to an unpredictable rate of infection and subsequent loss or resorption. These phenomena are to be feared, especially when transplantation beds are of inferior quality due to lack of soft tissue or decreased biological properties following irradiation. Therefore, Taylor investigated the blood supply of the iliac bone during his work with the groin flap, which is pedicled to the anterior superficial circumflex iliac artery (SCIA). He was able to demonstrate that a small piece of the iliac crest around the superior iliac spine was indeed supplied with blood by this vessel. However, the dimensions of this area were too small to be useful for larger reconstruction purposes (Taylor and Watson, 1978). Therefore he shifted his attention to the deep circumflex iliac artery (DCIA) and was able to show that this vessel not only supplies blood to nearly the whole iliac bone but also to a large area of skin flap overlying this bone and nourished by perforating vessel branches. He published the results of cadaver investigations and a first clinical case in November and December 1979 (Taylor et al., 1979). In August 1979 we had to reconstruct half of the mandible of a patient who suffered from a recurrent ameloblastoma. Utilizing our microsurgical experience, we harvested a bone graft pedicled on the DCIA. The anatomical situation was so clear in this thin patient that the DCIA came into

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Summary The technique of microsurgical vessel anastomosis has brought about many new ideas in reconstructive surgery. Many bone sites have been examined for their suitability as donor areas. For reconstructive purposes in the maxillo-facial region, the iliac bone has proven to be the best because of its shape and bulk. A large part of this bone is nourished by the deep circumflex iliac artery (DCIA). Branches of this vessel surround the iliac crest, perforate the flat abdominal muscles, and supply blood to the overlying skin. The anatomical properties of this region present the possibility of raising a large osteomyocutaneous flap.

Key-Words Iliac bone - Composite graft - DCIA - Microsurgery Anatomy - Transplantation.

consideration by mere accident. The relative ease of preparation made us feel this could be an extremely valuable method. We therefore turned to cadaver dissection to explore the topography of the deep groin area in order to standardize the harvesting procedure. Our work was completely independent of Taylor's, neither of us knowing anything about the other's efforts (Bitter, 1980). The aim of this publication is to show our anatomical and clinical results as well as to confirm those of Taylor and lend further support to this method of bone grafting.

Materials and Methods In 20 human cadavers, the SCIA and DCIA were exposed at their site of origin from the femoral artery via an incision along the inguinal ligament. Both arteries were cannulated and subsequently injected with a mixture of gelatine and black ink to delineate the area of blood supply. The different skin fields were documented by photography. Following this, the complete iliac bone area, including adjacent muscles, vessels and skin, was removed from the cadaver and dissected with the help of micro-instruments and magnifying lenses. The course of both vessels was followed distally by careful preparation to examine the distribution and branching into the deep groin tissue. Finally, the bone was removed from the soft tissue and cut into pieces. These pieces from different representative areas were cut and stained by routine histological methods to visualize the ink distribution within the bone marrow.

Results 1. Skin distribution Fig. 1 outlines schematically the superficial and deep groin area. The essential structures in microsurgical flap raising are the deep and superficial circumflex arteries. Note the blood supply from the SCIA to the anterior part of the iliac crest. In all 20 cadavers, the skin areas of the SCIA and the DCIA were equally well delineated and distinguishable, as can be

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- - E

C D

- - F - - G - - H - - I

K

Fig. 1 Groin region. A = DCIA; B = iliacus muscle; C = ascending branch of the DCIA; D = femoral artery; E = abdominal muscles; F = anterior superior iliacspine; G = skin; H = SCIA; I = inguinal ligament; K = superficial branch of the SCIA. (Bitter, 1980).

Fig. 2 View of the left lilac and groin area. S = skin field stained by dye injection into the SCIA; P = injection into the DCIA (p = profunda). Note the overlapping but nevertheless clear separation of the two fields.

seen in Fig. 2. In some cases, the stained fields were larger or smaller, reflecting the more or less advanced degree of autolysis in the dead tissue. When the fields were larger, the overlapping area was larger too. From this, it follows that both arteries are capable of substituting for one another within certain limits.

In 7 other cases, a branch could be detected running back to the distal part of the iliacus muscle and other muscles in this area (Fig. 3 b). The remaining 6 cases showed distal branching into the small pelvis (Fig. 3 c). Nevertheless, in all cadavers, the perforating branches which surround the iliac crest were present. These findings were later confirmed during our clinical work.

2. Vessel anatomy and variations The DCIA branches off from the femoral artery just beneath the inguinal ligament. From there, it swings slightly upward to run on parallel with, and just above the ligament. In all our cases, the artery was accompanied by two veins in close proximity to one another. In the area of arterial origin, the veins unite, and the single stem separates from the DCIA to run in a more upward direction, crossing over, or in a few instances, under the femoral artery to join the femoral vein. About 2-3 cm. before the DCIA reaches the anterior superior iliac spine, it sometimes sends off its ascending branch, which runs upward to the abdominal wall between the internal oblique and the transversus abdominis muscles (Fig. 3 a). We identified this branch 8 times in the 20 cadavers. The distal branching of the DCIA, i. e. beyond the anterior superior iliac spine, is depicted in Fig. 3 a-c. Among our 20 cadavers, we found three types, with a regular stem in all instances. This stem runs 2-3 cm. below and parallel with the iliac crest and lies in a sulcus formed by the border between the iliacus and the transversus abdominis muscle insertion. In 7 of 20 cases, the branches were small and arbitrary, supplying blood to the adjacent musculature and the underlying bone, and - what is most important surrounding the iliac crest to reach the overlying skin (Fig. 3 a.).

3. Blood supply to the iliac bone The microsurgical preparation of the ink-stained vessel finally led to a complete removal of the musculature and soft tissues. The course of the vessels could be followed up to the bone surface. There they disappeared through numerous foramina into the bone substance (Fig. 4). When the bone marrow was exposed, one could easily detect the black ink with the naked eye. Representative sections were made from three different parts of the iliac bone: one from the anterior crest area, one from the dorsal crest area, and one from the body about 10 cm. below the crest. Fig. 5 gives an example of ink staining in all the distinct parts.

4. Surgical preparation of the composite flap Fig. 6 depicts the skin incision for a graft which includes a small skin area. This area may be much greater, since the blood supply makes it possible to raise a skin flap which is much larger, as is usually necessary for reconstructive purposes in the head and neck region. The long axis of the desired flap has to conform to a line connecting the anterior superior iliac spine and the lower angle of the scapula. The incision passes through the skin down to the fascia, leaving this structure intact at this time (Fig. 7). Medially, the incision should not pass over the projection of the

The Iliac Bone or Osteocutaneous Transplant

Fig, 3 a DCIA with ascending branch (white vessel), l~t type: main stem with small branches into the underlying musculature and bone, atso surrounding the crest and penetrating into the overlying skin.

Fig. 3 c 3 rd type: main stem, but one or more thick branches into the rear of the pelvis,

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Fig. 3 b 2 ndtype: main stem as in type 1, but distinguished by a branch running back toward its origin.

femoral vein: otherwise, violation of the funiculus spermaticus might occur. Care must be taken to avoid tearing the skin island off the fascia, because it is only attached by very soft and delicate areolar tissue. As soon as the fascia has been incised, some rim sutures should be made to fix it to the skin. This simple aid prevents any shearing off. As can be seen in Fig. 8, the next step is to incise the femoral fascia just below and parallel with the inguinal ligament. The ligament itself is detached from the iliac spine. Following this, the whole system of the inguinal fascia can be pushed upward, exposing the DCIA and avoiding any injury with later herniation. The vessel is dissected out of the surrounding connective tissue with the help of magnifying lenses. If the ascending branch is present, it has to be decided whether it should be preserved or ligated. The decision depends on the design of the flap. Large flaps would surely benefit from this branch, whereas small flaps have no need of additional blood supply. If there is any uncertainty as to how to handle the ascending branch, one should postpone the decision and leave it untouched until a later stage. Before the DCIA reaches the iliac spine, it crosses under the branches of the nervus cutaneus femoris lateralis. This nerve can easily be preserved by gentle preparation. In obese patients, these branches are often overlooked because of the similar tissue colour (Fig. 12). The preparation is continued by excising the flap from the abdominal wall. To avoid the potential hazard of opening the peritoneal cavity, the raising of the skin flap must be done step by step, paying heed to anatomical structures.

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Fig. 4 Bone surface (3 x) with numerous foramina for small vessels. The black spot to the right is musculature, from which a relatively large v~ssel enters the bone (arrow).

Fig. 5 Cross-section of the iliac crest with black ink in all parts of the bone marrow.

Fig. 6 Design of skin incision for a composite graft. The skin flap chosen is small so as not to hide the structures lying underneath.

Fig. 7 Situation after completion of the skin incision. In this picture, the medial end has been extended beyond the justifiable border in order to demonstrate what can happen to the underlying structures if this border is not respected.

The abdominal wall in this region is formed by the three muscles. Because only the aponeurotic parts are encountered in the anterior part of the skin island, the flap raising is less difficult if one starts in the posterior region. Fig. 9 outlines clearly the three muscle layers which are to be incised consecutively. The ascending branch of the DCIA enters the flap at its anterior border to run between the internal oblique and the transversus abdominis muscles. At this point, it has to be decided whether this branch is to be preserved or ligated.

When the transversus abdominis muscle has been dissected, the transverse abdominal fascia is visible. This fascia is also incised: the last and most dangerous step of the abdominal wall incision. However, the peritoneum is still covered with the preperitoneal fat, which provides excellent protection. The fat layer is detached from the transversus abdominis fascia by blunt finger preparation, taking care that it is not damaged. This procedure is very easily done and exposes the whole inner aspect of the iliac bone as far as required for the bone transplant. The main stem of the DCIA can be

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Fig. 8 The femoral fascia is incised below the inguinal ligament. The ligament is detached from the anterior superior spine. The abdominal fascia, including the complicated inguinal system, can be pushed upward by blunt preparation, exposing the DClA.

Fig. 9 The skin flap is dissected out of the abdominal wall; the muscles are separated from each other to demonstrate the principle of preparation. Note the entrance of the ascending branch of the DCIA into the flap.

Fig. 10 The preparation has been continued by exposing the iliacus muscle surface. The covering fascia is not shown. The iliacus muscle has already been incised below the DCIA to expose the bony surface at a point where the bone transplant is to be cut off.

Fig. 11

Cross-section of the lilac bone with surrounding soft tissue. Note the DClA in the sulcus between the iliacus and the transversus abdominis muscles and the branching off of the vessels leading to the skin.

recognized in the sulcus between the insertions of the iliac and transversus muscles and is covered by the transversalis fascia (Fig. 10 and 11). Next, the iliacus muscle is incised below the DCIA, the exact point depending on the design of the bone transplant desired. The bone surface is exposed along the osteotomy line corresponding to the shape of the transplant. The outer

surface of the bone is exposed by the skin flap incision. In almost all cases, it is necessary to detach the gluteal musculature downward to expose the bone so as to achieve corresponding osteotomy lines from the inner to the outer aspect. The incision of the gluteal musculature is a bloody procedure, and care must be taken" not to overlook silent oozing.

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K. Bitter, T. Danai: Iliac B o n e or O s t e o c u t a n e o u s Transplant

fully. The use of two suction drains is recommended: one deep and one just below the subcutaneous fat.

Conclusion

Fig. 12 Operation after raising a pure bone transplant. The vessel pedicle and the cutaneous nerve crossing unterneat can be clearly distinguished,

The deep groin area presents excellent possibilities for the raising of an osteomyocutaneous flap. The DCIA is a 100 % reliable nutrient vessel. The potential hazards are: severing the nervus cutaneous femoris lateralis and, even more serious, injuring the peritoneal cavity. These risks, however, are calculable and can be minimized by paying proper heed to the clear-cut anatomy during preparation. The closure of the donor site, even in large skin flaps, is possible by mobilizing the abdominal wall, the tissue of which is soft and extensible. Postoperative herniation will not occur if the tissue layers are closed consecutively and carefully. Clinical experience with 10 cases will be outlined in the following paper.

Acknowledgement I am indebted to Miss Marianne Schindler for her skillful drawings. The required piece of bone is then cut with oscillating saws and osteotomes in the usual manner. If only a bone transplant alone is required, the skin incision parallel with the inguinal ligament is prolonged laterally along the iliac crest as far as is necessary to expose enough bone. The soft tissue from the outer aspect of the iliac bone is dissected and removed subperiosteally. Step by step, the insertion of the flat abdominal muscles is cut from the crest until the space between the transversalis fascia and the preperitoneal fat is reached. From this point on, the preparation follows exactly the same procedure as outlined for the composite graft. The closure of the donor defect has to be done layer by layer, otherwise a hernia might occur postoperatively. First, the iliac and gluteal muscles are to be united through the bone defect in order to avoid a haematoma. The cranial rim of the donor site wound can be mobilized downward to meet the edge of the iliac and gluteal musculature. The individual layers must be sutured consecutively and care-

References Bitter, K.: Bone transplants from the iliac crest to the maxillo-facial

region by the microsurgical technique. J. max.-fac. Surg. 8 (1980) 210-216 Taylor, G. L, N. Watson: One-stage repair of compound leg defects with 3 revascnlarized flaps of groin skin and iliac hone. Plastic and Reconstructive Surgery, 6] (1978) 494 Taylor, G. I., P. Townsend, R. Corlett: Superiority of the deep circumflex lilac vessels as the supply for free groin flaps. Plastic and Reconstructive Surgery, Vol. 64 (1979) 595-604 Taylor, G.I., P. Townsend, R. Corlett: Superiority of the deep circumflex iliac vessels as the supply for free groin flaps. Clinical Work. Plastic Reconstructive Surgery, Vol. 64 (1979) 745-759 Prof. Dr. Dr. K. Bitter Dept. of Maxillo-FacialSurgery Joh.-W.-Goethe-Universit~it Theodor-Stern-Kai 6000 Frankfurt~Main