Source British Journal of Plastic Surgery Volume: 50 Number: n/a March 1997

The donor site morbidity of free DIEP flaps and free TRAM flaps for breast reconstruction

Ph. N. Blondeel*, G. G. Vanderstraetent, S. J. Monstrey*, K. Van Landuyt*, P. Tonnard*, R. Lysens**, W. D. Boeckx and G.Matton.

Departments of Plastic and Reconstructive Surgery and "Physical Medicine and Rehabilitation, University Hospital Gent, and Departments of Physical Medicine and Rehabilitation and Traumatology and Reconstructive Surgery, University Hospitals Leuven, Belgium

SUMMARY This study was undertaken to demonstrate that the deep inferior epigastric perforator (DIEP) flap can provide the well-known advantages of autologous breast reconstruction with lower abdominal tissue while avoiding the abdominal wall complications of the transverse rectus abdominis myocutaneous (TRAM) flap.

Eighteen unilateral free DIEP flap breast reconstruction patients were assessed 12-30 months (mean 17.8 months) after surgery. Clinical examination, physical exercises and isokinetic dynamometry were performed preoperatively and two months and one year postoperatively. Intraoperative segmental nerve stimulation, visual evaluation and postoperative CT scans were also used to quantify the damage to the rectus muscle. The 18 patients were then compared with 20 free TRAM flap patients and 20 non-operated controls.

Two DIEP flap patients presented with abdominal asymmetry. A limited decrease of trunk flexing strength was noticed but rotatory function was intact. Ten of the TRAM flap patients had umbilical or abdominal asymmetry, bulging or hernias. TRAM flap patients showed a statistically significant reduction in strength to flex and to rotate the upper trunk compared to both the one year postoperative DIEP flap group and the control group. The answers to a questionnaire revealed impairment of activities of daily living for some TRAM flap patients while the activities of all DIEP flap patients were unaffected.

Our data demonstrate that the free DIEP flap can limit the surgical damage to the rectus abdominis and oblique muscles to an absolute minimum. We believe it is worthwhile to spend extra operative time, the main disadvantage of this technique, to limit late postoperative weakness of the lower abdominal wall.

The pedicled or free transverse rectus abdominis myocutaneous (TRAM) flap has been regarded as the gold standard in autologous breast reconstruction during the last decade. Although the aesthetic appearance of the donor area is superior to other flaps, the main disadvantage remains the sacrifice of small (free TRAM) or larger (pedicled TRAM) parts of the rectus abdominis muscle. Parts of this muscle were harvested because it was generally considered that the deep inferior (free TRAM) or superior (pedicled TRAM) epigastric vessels and their pare-umbilical perforating branches, that run through the muscle and supply the overlying lower abdominal skin and subcutaneous fat, could not be isolated. Weakness of the lower abdominal wall due to this surgical resection was responsible for loss of function, abdominal bulging, asymmetry of the umbilicus and the abdominal wall, and hernias. To reduce donor site morbidity, more attention has been given recently to limiting the amount of muscle resection.

Koshima and Soeda' were the first to describe the 'inferior epigastric artery skin flap without rectus abdominis muscle'. Three years later Koshima et al.2 renamed the same flaps 'free thin paraumbilical perforator-based flaps'. These flaps were small and used for the reconstruction of soft tissue defects other than breasts. Allen and Treece3 were the first to use a similar free deep inferior epigastric perforator (DIEP) flap with dimensions equal to the TRAM flap for breast reconstruction. We reported how to deal with median laparotomy scars and how to increase the surface area of the skin by dissecting bilateral pedicles.4,5 By sagittally splitting the rectus abdominis muscle in a plane where the largest perforators emerge out of the muscle, lower abdominal skin and fat can be harvested and the rectus abdominis 'muscle can be left practically undamaged. Although it seems obvious that with this surgical technique the function of the rectus abdominis muscle would remain intact, no objective evidence has yet been published demonstrating an effective reduction in donor site morbidity. In this study, we evaluated in a prospective manner the function and the strength of the abdominal wall of patients who underwent a free DIEP flap breast reconstruction. These data were compared to a control group and retrospectively to a group of patients who had undergone free TRAM flap breast reconstruction.

Patients and methods

Patient groups

Since January 1994, the first author has performed 58 free DIEP flaps for breast reconstruction in 53 patients. Eighteen female patients with a unilateral breast reconstruction now have a follow-up of at least one year (mean 17.8 months, range 12-30 months) and constitute the subject of this study. All patients had undergone a unilateral mastectomy for carcinoma. In 6 patients a primary breast reconstruction was performed. No patient selection was taken into account and risk factors such as obesity (Body Mass Index > 30), radiotherapy, smoking and abdominal scarring were not excluded (Table 1). Three patients (17%) had no risk factors, 4 patients (22%) one and 11 patients (61%) more than one risk factor. The harvesting of the unilateral DIEP flap was done in a similar way to that published earlier.4 The abdominal wall strength of the 18 patients was evaluated in a prospective manner preoperatively (DIEP pre-op), 2 months (DIEP2mo.) and 12 months postoperatively (DIEP12mo.). After an initial decrease 2 months postoperatively, the mean weight of these patients returned to near preoperative values one year postoperatively (Table 1). These changes were not statistically significant.

Twenty free TRAM flap patients with at least one year follow-up (mean 32.05 months), were submitted to the same set of tests, as previously reported.6 The free TRAM flaps were dissected in the standard fashion. Above the arcuate line, the entire width of the muscle was harvested over a length of approximately 6 8 cm. Closure of the anterior rectus sheath was reinforced by a synthetic mesh in 18 cases. Indications for mastectomy in the TRAM flap patients included malignant tumors of the breast (18 cases), congenital aplasia and unilateral hypotrophy following radiotherapy as a child. A comparable high number of risk factors was encountered in this group (Table 1). Four patients (20%) had no risk factors, 5 patients (25%) one and 11 patients (55%) more than one risk factor.

Finally, a control group was composed of sisters or female acquaintances of the DIEP or TRAM flap patients who volunteered to perform the same tests. In that way we were able to build up a group that was comparable in age, weight, physical condition and socio-economic habits. The mean ages and weights were comparable in all 3 groups (Table 1).

Evaluation of abdominal wall strength

Clinical examination. All patients were examined supine and upright for asymmetric positioning of the umbilicus, abdominal wall asymmetry, lower abdominal bulging, and hernias by a physician other than the surgeons.6
Physical exercise evaluation. Patients were rated for their straight and rotational curl-up performance following the same descriptive measures as reported previously.6 A higher score was given to a better curl-up performance following the criteria in Table 2 (modified from Janda). During the rotational curl-up, patients were asked to turn the upper body and bring the elbow to the contralateral knee. Left and right rotation were tested. Evaluations were done independently by a physician other than the surgeons.

Isokinetic dynamometry. The same set-up for the Cybex II isokinetic dynamometer (Cybex, Division of Lumex, Inc., Ronkonkoma, N.Y.) was applied as described previously.6
Questionnaire. A self-administered questionnaire was sent to all patients in the DIEP and TRAM group, at least one year postoperatively.

Assessment of rectus muscle viability

The following investigations were done in the DIEP flap group only.

Intraoperative visual inspection of the rectus muscle was a strictly subjective estimation of the percentage of the entire rectus muscle that appeared to be damaged after dissection of the flap. The most important criterion of damage to a part of the muscle was the colour of the muscle. Any colour different from normal, mostly bluish purple, was considered a sign of bruising, venous stasis or ischaemia. Other criteria were bleeding from the muscle and oedema.

Intraoperative nerve stimulation of the mixed segmental nerves was performed at 2 mA at the lateral border of the rectus muscle after harvesting of the flap. The muscle segments lateral and medial to the longitudinal muscle incision were inspected for contractility.

Postoperative CT-scanning or MRI of the abdominal wall was performed in 12 patients to evaluate atrophy or fatty infiltration of the rectus muscles. The umbilicus served as a point of reference. As no muscle dissection took place above the level of the umbilicus, imaging was only performed between the umbilicus and pubis. The cross-sectional areas of both rectus muscles were calculated and compared to each other. The percentage of area reduction of the operated side was divided into 4 categories: <5%, 5-10%, 1~20% and >20%.

Testing and statistics

Two different comparisons were done in this study.

DIEP flap group. The results of the standard testing set, which consisted of a clinical examination, physical exercise evaluation and isokinetic dynamometry were compared preoperatively, 2 months and 12 months postoperatively in the same patients in a prospective manner. These patients form a group of paired variables.
TRAM flap group vs. DIEP 12mo. and control group. As TRAM flap patients had not undergone a preoperative evaluation, no assessment could be made of the degree of postoperative decline in abdominal wall strength. Therefore we were only able to make a retrospective comparison of the results of the standard set between the control subjects, the DIEP12mo. subgroup and TRAM flap patients. They form a group of unpaired variables.

To compare the curl-up score the chi squared test was used for the first comparison and Fisher's exact test for the second. To compare the dynamometric results between groups the Kruskal-Wallis ANOVA and Mann-Whitney test were used. P < 0.05 was considered as statistically significant.

Results

Clinical examination

In the DIEP preoperative group, two patients presented with an umbilical hernia that was repaired during surgery. In the control group, three subjects had an umbilical hernia. The DIEP2mo. group demonstrated a firm abdomen in all cases. The results of the clinical examination in the DIEP12mo. group and the TRAM group are shown in Table 3. A CT scan did not show a defect in the deep abdominal fascia of either patient with abdominal wall asymmetry in the DIEP12mo. group. Ten of the patients in the TRAM flap group had abdominal wall anomalies.

Figure 1—Physical examination. Percentages of subjects able to achieve muscle power scores of 3, 4 or 5. (Straight: Straight curl-up. Left: Left rotational curl-up. Right: Right rotational curl-up.)

Physical exercise evaluation

DIEP flap group. Preoperatively all patients were able to perform a full straight curl-up as well as a rotational curl-up of which 15 (83%) were at the highest level, score 5 (Fig. 1). This is comparable to the control

group (16 patients, 80%). The overall muscle score decreased when patients were tested soon after surgery, but the highest score was still achieved by 12 patients (67%) for straight and 11 patients (61%) for rotational curl-ups. Twelve months after surgery, only one patient (6%) was not able to perform a full curl-up. The range of muscle power scores in the DIEP12mo. group was similar to the preoperative range. No statistically significant differences were found between the three groups.

TRAM flap group vs. DIEP12mo. and control group. Results for-the TRAM flap group have been detailed elsewhere (6) and are shown in Figure 1.

Comparing patients with score 5 to patients with score 3 or 4, the straight curl-up performance of TRAM flap patients was significantly lower than DIEP flap patients one year postoperatively (P = 0.011) and controls (P = 0.001). Left rotational curl-up performance was lower than right rotational curl-up performance in TRAM flap patients, and differences from the DIEPl2mo. group (left: P < 0.001; right: P = 0.003) and the control group left: P < 0.001; right: P = 0.001) were significant.

Isokinetic dynamometry

DIEP flap group. Assessing the extension exercise, the mean peak torque/body weight (pt/bw) and mean average power/body weight (ap/bw) were comparable preoperatively, at 2 and at 12 months postoperatively. In the flexion exercise, the mean pt/bw decreased gradually over time. The mean ap/bw initially decreased but improved slightly after one year. The flexion over extension ratio for mean peak torque and average power showed a slight gradual decrease. The mean pt/bw and ap/bw of the rotational movements initially decreased after 2 months but returned to values similar to the preoperative values. None of the changes for the different movements or the changes in the left/right rotation ratio were statistically significant.

TRAM flap group vs. DIEP12mo. and control group. (Table 4). Although the mean pt/bw and ap/bw for the extension exercise were lower in TRAM flap patients, the differences between the three groups were not statistically significant. The mean pt/bw and ap/bw for TRAM flap patients flexing the upper body were significantly lower than those of DIEP flap patients or controls. The flexion/extension ratio for peak torque and average power in TRAM flap patients was not significantly lower than the ratios in the DIEP12mo. and control groups. For the rotational forces the mean pt/bw and ap/bw for TRAM flap patients were significantly lower than those of DIEP flap patients or controls. Except for the pt/bw for left rotation, the differences between the DTEP12mo. group and the TRAM flap group were not significant while the differences between the TRAM flap group and the control group were. The left/right rotation ratio was similar in all groups.

CT or MRI of the abdominal wall

Imaging studies of the lower abdominal wall were performed in 12 of the 18 DIEP flap patients one year postoperatively. Ten of these 12 patients showed less than 5% muscle atrophy or fatty infiltration of the operated muscle compared to the contralateral non-operated side. One rectus muscle was calculated to have muscle atrophy between 5 and 10% and one between 10 and 20%. No defects of the abdominal fasciae were visualized. Normal anatomical proportions were seen in all cases (Fig. 2), in contrast to the change that occurred in TRAM flap patients (Fig. 3).

Intraoperative visual inspection

Fourteen muscles (78%) were graded to have less than 5% visible damage of the entire rectus abdominis muscle after DIEP flap harvesting. Another 3 muscles (16%) were judged to have between 5 and 10% damage and one additional muscle (6%) to have between 10 and 20% damage.

Fig.2

Fig. 3

Figure 2—Horizontal MRI cut at the level of the umbilicus (v) of a unilateral free DIEP flap patient. The vessels were harvested on the right side. Muscle atrophy or fatty infiltration was estimated to be less than s% in this case. Figure 3 - A) Horizontal MRI cut at the level of the umbilicus (v) of a unilateral free TRAM flap patient. The muscle was harvested on the left side. Displacement of the contralateral rectus muscle over the midline, narrowing of the empty rectus fascia (between white arrows) and a decreased distance between the insertion lines of the oblique muscles of both sides (between black arrows) are typical images for TRAM flap patients. The distance between the linea alba and the medial border of the external oblique muscle is noticeably lower on the operated side (DI I = 42.3 mm) than on the right side (D1 2 = 97.1 mm). (B) same MRI cut indicating also a reduced distance between the linea alba and the medial border of the internal oblique muscle on the operated side (Dl 3 = 76.8 mm) compared to the right side (D1 4 = 92.3 mm)

Intraoperative nerve stimulation of the rectus muscle

The segment of muscle lateral to the muscle incision contracted on nerve stimulation in all the DIEP flap patients. The medial part of the muscle contracted on nerve stimulation in 15 cases (83%).

Questionnaire

Sixteen of the 18 DIEP flap patients and 19 of the 20 TRAM flap patients returned the questionnaire. The results are shown in Tables 5 and 6. More TRAM flap patients than DIEP flap patients complained about loss of power in the abdominal wall, unilateral or bilateral protrusions, umbilical asymmetry, chronic pain in the lower abdominal wall when intra-abdominal pressure was raised (coughing, Valsalva, etc.) and problems in getting up from a supine position.

In contrast to the TRAM flap patients, all DIEP flap patients were able to continue to do their domestic tasks, sports activities and hobbies in the same way

they did preoperatively. Overall satisfaction was high and comparable in both groups. All patients in both groups would recommend their operation to somebody else.

There was a very small increase in lower back pain in both the DIEP patients and the TRAM flap patients after surgery (Table 6).

Table 5 Results of the questionnaire

 

Discussion

The free deep inferior epigastric perforator (DIEP) flap is the first of a new generation of arterialised skin flaps called 'perforator' flaps. The DIEP flap was first described by Koshima et al.' Since then, the superior gluteal artery perforator flap has been described by Allen and Tucker,8 the thoracodorsal perforator flap by Angrigiani et al.9 and perforator flaps based on the lateral circumflex femoral system by Koshima et al. The often substantial donor site morbidity of many myocutaneous flaps has refuted the general belief that the function of certain resected muscles can be taken over by synergists. With additional microsurgical effort, all the above mentioned flaps, previously myocutaneous, can now be dissected strictly as skin flaps. All flaps of this new group have a number of common characteristics: donor site morbidity is limited by preserving all muscle tissue through which the vessels run, flow through the perforating vessels is increased by redirecting a part of the blood flow of the muscle into the skin and, finally, the mobility of the flap, pedicled or free, has been increased by longer vascular pedicles. Meanwhile, the intrinsic advantages of each flap are preserved.

Kroll et al." and Mizgala et al.'2'3 reported that the degree of abdominal wall weakening is proportional to the amount of sacrificed rectus abdominis muscle. Theoretically, this implies that total sparing of the rectus muscle could lead to complete preservation of abdominal wal1 strength. The aim of our prospective study was to determine the validity of this hypothesis, as this has not yet been confirmed by any previous study.

The first indications that damage to the rectus muscles could be limited came from visual peroperative observation of the viability of the rectus muscle and the ease with which the abdomen could be closed in our earliest DIEP flap cases. It was clear that the blood vessels proximal and distal to the area of dissection ensured sufficient blood flow to the medial strip. Although direct visual inspection is subjective, we continued to assess muscle damage in order to correlate our impressions with the radiological imaging. In one case where the degree of intraoperative damage was estimated to be high (10-20%), a clear area of muscle atrophy could be identified on CT scan. In patients with estimated ischaemia or damage of less than 5%, no significant changes could be seen on CT scan or MRI.

When the rectus muscle is split along the direction of the muscle fibers, the large motor branches of the segmental nerves coming from laterally can be identified. At the point where the segmental blood vessels anastomose with the epigastric vessels the motor branches continue mostly anterior to the main epigastric vessels. The pedicle can be dissected deep to the motor nerves so that the nerves are spared. Only if one of the motor branches lies between two perforators, does this branch have to be divided to harvest the flap. This was the main reason why the response to peroperative segmental nerve stimulation of the muscle segment medial to the vertical incision was negative in 18% of the muscles. Most of the divided nerves were sutured. Based on the CT scan findings, we presume that nerve outgrowth of the sutured nerves to the medial part of the muscle can take place and that smaller invisible branches can aid in the reinnervation process by neurotization.

Even if the rectus muscle and the anterior rectus sheath are not resected, some surgical damage is always inflicted on the abdominal wall by dissecting the vessels and reducing local blood flow. Simple coaptation of the anterior fascia was sufficient to restore perfectly the firmness of the abdominal wall in all free DIEP flap patients, except for two with limited asymmetry of the abdominal wall. As no muscle atrophy and no defect in the abdominal fascia could be found on CT scans, we believe that scar distension in the anterior rectus sheath was responsible for the laxity. No bulges or hernias were diagnosed in the DIEP flap patient group. The number of anomalies of the abdominal wall on clinical examination in this study was significantly lower in the DIEP flap group compared to the TRAM flap group. Although all patients with abdominal asynunetry or bulging were free of complaints, this did result in aesthetic deformities.

For reasons discussed previously (6) we preferred using the curl-up test with foot support instead of the sit-up test to clinically evaluate the flexing and rotating capacities of the trunk. As the isokinetic dynamometry showed that the DIEP flap patient's general condition did not differ from the preoperative situation, we assume that changes in the undamaged iliopsoas muscles were probably limited and therefore a decline of curl-up performance, with feet supported, largely depended on reduced rectus muscle strength. Incomplete rehabilitation and disuse after surgery are the most probable causes for an initial decrease in curlup performance in the DIEP flap patients 2 months postoperatively. The ability to execute a full curl-up fully returned 1 year postoperatively. The surgical intervention on the rectus muscle had either no or a limited effect on the ability to flex the trunk in DIEP flap patients, in contrast to TRAM flap patients who were not able to score as high as the DIEP flap patients and the control group. Differences became even more significant for rotatory movements. Although in a foot supported curl-up, the influence of the iliopsoas muscles can be reduced but not excluded by flexing the hips, we may presume that eventual changes in the strength of the iliopsoas muscle during or after DIEP or TRAM flap surgery would be similar. Therefore the resection of rectus muscles in TRAM flap patients is directly responsible for the reduction in abdominal wall strength.

Isokinetic dynamometry is a reliable and reproducible method to measure the force or power of the trunk.(11-17) Trunk extension was tested to assess the patient's general condition. A minimal deterioration of the patient's general condition would immediately be reflected in a decreased peak torque and average power because the back muscles will be the first to weaken, if they are not used. In the DIEP flap patients, there was no significant change in extension after surgery.

In the DIEP flap group, there was a decrease of mean peak torque and average power to flex the trunk 2 months after surgery. After 1 year, there was a further decrease of the mean peak torque while the average power was slightly increased. These changes were not statistically significant. As it is unlikely that rectus muscle strength would increase after surgery or the untouched iliopsoas muscles would decrease in strength, as explained earlier, we assume that this slight decrease in power was caused by dissecting the epigastric vessels out of the rectus muscle. On the other hand, the denervation of the medial muscle strip in 18% of the cases and the reduced blood supply in the area of dissection could be responsible for the slight decreased flexing capacity. Neurotization of this segment might help restore muscle bulk but would be unlikely to restore muscle strength. Comparable to tendon transfers in hand surgery,8 destruction of important areas of epimysium around the rectus muscle add pert-muscular iatrogenic scar formation can lead to a reduced gliding capacity of the rectus muscle. Intramuscular scar tissue, caused by splitting the muscle, reduces the useful length of contraction and makes the muscle less effective. Although we believe that these are the most important reasons for the slightly reduced flexing power, isometric dynamometry studies are needed to confirm this theory. Disuse can be ruled out because the general condition of the patients did not decline and all patients returned fully to their preoperative activities 1 year after surgery.

The trunk flexion capacity of TRAM flap patients was significantly lower than the control group and the DIEP flap patients 1 year after surgery. Assuming that the patients' general condition and the iliopsoas muscles did not alter significantly and that the postoperative course in the DIEP and TRAM flap groups was similar, the resection of a part of the rectus muscle can be held responsible for the statistically significant difference of trunk flexion capacity between DIEP and TRAM flap patients.

No changes occurred in the mean peak torque and average power of the rotational movements in the DIEP flap group throughout the whole course, in contrast to the statistically significant decrease of power in the TRAM flap group. The possible reasons for loss of strength in the rotational movements in TRAM flap patients have been discussed previously.6 After DIEP flap harvesting, the rectus muscles are strong enough to tense the central muscular pillar. By not resecting the rectus muscle and the anterior rectus fascia, deviation of the contralateral rectus muscle will not occur. Therefore the insertion line of the oblique muscles is not displaced medially, the oblique muscles remain capable of exerting normal pulling forces and no rotatory function is lost. This explains the very few repercussions on activities of daily life in the DIEP patients.

CT scans or MRI of the abdominal wall of the DIEP flap patients showed 5-10% and 1-20% muscle atrophy in 2 of 12 patients (xamined and normal anatomical proportions in all 12 cases.

The objective data were correlated with the patients' subjective opinions. More TRAM flap patients than DIEP flap patients considered the aesthetic appearance of their abdomen to be worse but their silhouette to be improved after surgery. More of the TRAM flap patients found their abdominal strength to be reduced, although there was no difference in the ability to lift heavy objects. Chronic lower abdominal pain was reported by almost 50% of the TRAM flap patients and 25% of the DIEP flap patients. More TRAM flap patients needed support by their arms to get up from a supine position. None of the DIEP flap patients reported any change in their ability to perform their profession, hobby, sports or domestic jobs. These daily living activities needed adjustment or were discontinued in respectively 5%, 20%, 50% and 26% of TRAM flap patients after surgery.

During the early days of autologous breast reconstructions, interest was focused on the aesthetic appearance of the breast and abdomen. After the surgical techniques became standardized, more emphasis was put on limiting the amount of rectus muscle resection.11-22,19-22 Perforator flaps reduce donor site morbidity to the lowest level yet possible. In addition to the well known advantages of autologous breast reconstruction with lower abdominal tissue, the DIEP flap eliminates most of the disadvantages of the TRAM flap. After going through an initial learning curve, the tedious dissection of the vessels and nerves has now become routine for us. The increased operating time and costs involved do not outweigh the long term benefits for the patient. Aiming to sacrifice or damage as little as possible and to reconstruct as much as possible in one stage, we probably will have to learn to work in even smaller microsurgical dimensions than we are doing at present. We believe that the perforator flaps are probably only an introduction to the field of 'supra-microsurgery', a new area where minuscule and very delicate microsurgical dissections and sutures will be safely performed with the aid of new optical devices and instruments.

Acknowledgements

We wish to thank Dr K. Depuydt, Mrs L. Vervaet and Mrs I. Didden for their efforts in physically and clinically evaluating the patients. We also wish to express our gratitude to Mr G. Vanmaele for his statistical work.

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The Authors

Phillip N. Blondeel MD, FCCP, Associate Professor, Department of Plastic and Reconstructive Surgery, University Hospital Gent

Guy G Vanderstraeten MD, PbD. Professor and Chief of the Department of Physical Medicine and Rehabilitation University Hospital Gent

Stan J. Monstrey MD, PhD, FCCP, Professor and Chief of the Department of Plastic and Reconstructive Surgery, University Hospital Gent

Koenread Van Landuyt MD, FCCP, Associate Professor, Department of Plastic and Reconstructive Surgery, University Hospital Gent

Patrick Tonnard MD, FCCP, Clinical Assistant Professor, Department of Plastic and Reconstructive Surgery, University Hospital Gent

Roeland Lysens MD, PhD, Professor and Chief of the Department of Physical Medicine and Rehabilitation, University Hospitals Leuven

Willy D. Boeckx MD, PhD, Professor, Department of Traumatology and Reconstructive Surgery, University Hospitals Leuven

Guido Matton MD, FACS, Emeritus Professor and former Chief of the Department of Plastic and Reconstructive Surgery, University Hospital Gent

Correspondence to Phillip N Blondeel, Department of Plastic and Reconstructive Surgery, University Hospital Gent, De Pintelaan 185, B-9000 Gent, Belgium.

Paper received 8 November 1996. Accepted 19 March 1997, after revision.