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British Journal of Plastic Surgery (1997), 50, 37k-379 0 1997 The British Association of Plastic Surgeons

Ischial pressure sore coverage: a rationale for flap selection

R. D. Foster, J. P. Anthony, S. J. Mathes and W. Y. Hoffman

Division of Plastic and Reconstructive Surgery, University of California at San Francisco, California, USA

SUMMARY The role of wound debridement and flap coverage in treating pressure sores is clearly established. However, criteria and supportive clinical data for specific flap selection and the sequence of flaps for coverage of the ischium remain ill-defined. From 1979-1995, 114 consecutive patients underwent flap coverage of 139 ischial pressure sores. Preoperative risk factors, prior flap history, defect size, flap success, complication rates, and the length of hospitalization were retrospectively evaluated and compared for 112 flaps in 87 patients. Flap success was defined as a completely healed wound. Average follow-up was 10 months (range: 1 month-9 years).

Overall, 83% (93/l 12) of the flaps healed. In the majority of cases (75%, 84/l 12), wound debridement and flap reconstruction was achieved in a single stage. However, there were significant differences in the healing rates among the various flaps used. The inferior gluteus maximus island flap and the inferior gluteal thigh flap had the highest success rates, 94% (32/34) and 93% (25/27), respectively, while the V-Y hamstring flap and the tensor fascia lata flap had the poorest healing rates, 58% (7/12) and 50% (6/12), respectively. Flap success was not significantly affected by the age of the patient or the prior number of flaps used and preoperative risk factors were equally distributed across all types of flaps. The overall complication rate was 37% (41/112), most commonly from a slight wound edge dehiscence (n = 16) that healed with local wound care within one month postoperatively.

Results of this study show that proper flap selection and the appropriate sequence of flap use significantly improve success rates for ischial pressure sore coverage in both the short- and long-term. Based upon flap reliability (successful healing rates), reusability, and the need to preserve as many future flap options as possible, a rationale for flap selection is presented which can be individualized to any patient.

Accepted current surgical management of pressure sores consists of thorough debridement including involved bone, followed by flap coverage.’ Despite this and other non-surgical measures, pressure sore recurrence rates can still exceed 50%.* Frustration with these results has prompted a subset of surgeons to suggest that perhaps some or all of these patients have little to gain from any operative treatment.* However, much of the data to support this pessimistic view is based on initial operative success rates of only 80%.* Since pressure sores which fail to heal while the patient is hospitalized virtually never heal after discharge, the early postoperative results will clearly contribute to future outcomes.

Our experience has led us to believe that the most important step for early treatment success is appropriate flap selection. The spectrum of flaps used for ischial coverage includes the gluteus maximus, posterior thigh,4 hamstring,5 biceps fernoTis tensor fascia lata,’ gracilis,’ rectus abdominis’ and anterior thigh flaps.‘O Despite this wide variety of coverage options, the ischium remains the most difficult pressure sore site to treat.”

The optimal approach to pressure sore coverage should include utilization of the most reliable flap to achieve a healed wound, while preserving as many future flap options as possible. Despite the widespread use of myocutaneous flaps in the treatment of pressure sores, few studies have critically analysed flap reliability, comparing one flap to another. The purpose of this study was to examine our 17-year surgical experience

with flap reconstruction for ischial pressure sore coverage and to compare and contrast flap reliability rates in obtaining a healed wound. Treatment efficacy was also analysed from several other perspectives including a flap’s versatility for reuse, thereby main- taining as many future flap options as possible. Based upon these results, we have substantiated a rationale for flap coverage designed to treat a patient over his/her lifetime.

Patients and methods

From 1979 to 1995, 114 consecutive patients underwent flap coverage of 139 ischial pressure sores. From this group, there was adequate information available to permit detailed analysis of patients’ records for 112 flaps in 87 unselected patients (64 men, 23 women). Several patients had bilateral and/or recurrent ischial sores. The mean age of the patients was 49 years (range 16-90 years).

Chronic wounds (present for > 3 months) repre- sented 52% (58/112) of the total number of cases. In most cases the patients were paraplegic (89%) or quadraplegic (4%) and only 7% were ambulatory. In 75% (84/l 12) of the cases, the patients had their pressure sore debrided and reconstructed in a single stage. Patients were confined to bedrest postoperatively, usually on an air-fluid bed, for lo-14 days followed by a programme of gradually increased weight-bearing (sitting) on the ischial area.

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Ischial pressure sores 375

Table 1 Flaps selected and primary healing rates

Flap No. of eases Healed primarily (‘S) (54)

Inferior gluteus maximus island 34 (30.4) 94 Gluteal thigh 21(24.1) 93 Gracilis 16 (14.3) 75 V-Y hamstring 12 (10.7) 58 Tensor fascia lata 12 (10.7) 50 Anterior thigh 6 (5.3) 100 Rectus abdominis 5 (4.5) 100

Flap success and primary healing were defined as a healed wound within one month postoperatively, usually corresponding to the time of wound suture removal during the patient’s first follow-up visit. Reconstructive failure was defined as a case resulting in a non-healed wound. Follow-up ranged from 1 month to 9 years (average 10.7 months).

The flap selection for ischial sore coverage is listed in Table 1. Only musculocutaneous and/or fasciocutaneous flaps were included in this series. The inferior gluteus maximus island flap was most commonly used (30.4%, 34/l 12) followed by the inferior gluteal thigh flap (24.1%, 27/112). Five of the six ambulatory patients were reconstructed with gracilis flaps. Flap success (healing) was compared between each flap. Risk factors for impaired wound healing, based on prior wound healing studies,‘2.‘z and complication rates were determined for each reconstruction. The age of the patient, number of prior flaps and defect size following debridement were analysed independently to test their effect on subsequent flap success. Significance was determined post hoc by the Chi squared test.

Results

Overall, 83% (93/l 12) of the flaps healed primarily. 89% (75/84) of the cases treated in a single stage (debridement and flap reconstruction) healed primarily. For grossly infected (necrotic tissue) sores treated in a single stage, flap success was also 89%.

For flaps in which we had a significant experience (>lO cases), the inferior gluteus maximus island flap and the inferior gluteal thigh flap, had the highest success rates, 94% (32/34) and 93% (25/27), respectively (Table l), followed by the gracilis flap, the V-Y hamstring flap and the tensor fascia lata flap. The hospital stay averaged 21 days, 16.5 days for patients without prior complicated medical histories. The time to heal averaged 38 days. The earliest time healing could have occurred, as defined in this study, was 28 days (the earliest time of suture removal).

Complications occurred in 41 (37%) of the reconstructions (Table 2). There were no intraoperative deaths or significant donor site complications. A slight wound edge dehiscence (not > 1 cm in length or width) occurred in 16 patients but all of these wounds healed with local wound care alone within one month postoperatively. When flaps failed to heal, requiring further operative management, it was usually the result of

Table 2 Complications

Slight wound edge dehiscence (healed with local wound care) 16 Partial flap necrosis 10 Wound infection 5 Wound dehiscence (requiring reoperation) 5 Died, unrelated causes 2 Aspiration pneumonia 1 Intraop. myocardial infarct 1 Deep venous thrombosis 1

either partial flap necrosis (n = lo), inadequate debridement and the subsequent failure to adequately control infection (n = 5) or wound dehiscence (n = 5). Reoperation following instances of treatment failure involved either readvancement of a flap or harvesting of a different flap. The results of these decisions are included in the flap selection totals in Table 1. Flap necrosis was seen exclusively in one of three flaps: the tensor fascia lata flap (n = 5), gracilis (n = 3), and the V-Y hamstring (n = 2). Flap necrosis of the tensor fascia lata and gracilis flaps was always confined to the distal one third of the flap. Three out of five cases of wound dehiscence that ultimately failed to heal involved the proximal suture line across the V-Y hamstring flap. The other two cases of dehiscence were attributed to excessive tension with the wound closure. None of the ambulatory patients experienced signili- cant limitations to their range of motion or gait in the long term.

Among individual flaps, the inferior gluteus maximus island flap appears to be very reliable. Although 6 cases resulted in a slight wound dehiscence successfully managed with local wound care, no specific factor(s) could be identified that would limit this flap’s use. The only failed flap was the result of inadequate debridement. The inferior gluteal thigh flap was also very reliable. The two cases of failed reconstructions with the inferior gluteal thigh flap were the result of inadequate debridement (1 patient) and extremely poor patient compliance (1 patient) resulting in wound breakdown. A slight wound edge dehiscence did not prevent healing in four additional patients.

In 67 cases (60%) prior flap reconstruction had been performed. Overall, 84% (38/45) of the flaps in patients without any prior reconstruction healed primarily compared to 79% (53/67) with prior flap coverage. 77% of flaps with one prior flap healed successfully, 79% with two prior flaps and 81% with three or more flaps (Fig. 1). Flap success was not affected by prior flap reconstructions (P = 0.58, Chi squared test). Therefore, although certain flaps are not used as first-line coverage (TFL, gracilis) this does not appear to significantly affect their healing rates.

The average size of the debrided wound prior to reconstruction was 75 cm*. When the size of the defect following debridement was analysed to determine an effect on healing, smaller defects (an average of 59.6 cm’) were paradoxically less likely to heal successfully (P = 0.0089, Chi squared test) (Fig. 2). Healed wounds averaged 82.9 cmZ. It is possible that some other risk factor(s) was related both to the size of the wound and the outcome. It is also possible that this difference may be an artefact of the imbalance in

376 British Journal of Plastic Surgery

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z z h 30

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Number of prior flaps

Fig. 1

q Healed q Not healed I

I q Healed q Not healed

*P = 0.0089

Pressure sore area (cm2)

Fig. 2

Figure l-Prior ischial flap reconstructions vs. healing. Figure 2-&e of debrided ischial pressure sore vs. healing.

sample sizes between those ischial sores that healed Table 3 Risk factors for impaired wound healing versus those that did not heal. Further review of this subset of patients showed that 71% (15/21) of flaps in patients with small wounds had more than one risk factor for impaired wound healing (Table 3).

With an average follow-up of 10.7 months, 17% (19/l 12) of the pressure sores recurred. Although the TFL flap (for ischial coverage) seemed to recur most frequently, the sample size was too small to perform any significant comparative analysis between the various types of flaps. In addition, the relatively short- term average follow-up precludes any in depth analysis of recurrence rates.

Age >65 years Smoking Diabetes Renal failure Wound infection Systemic infection Local radiation Immunosuppressive agents Haemodynamic instability Prolonged hyperalimentation Low total protein

(List generated from previous wound healing studies.12,“)

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Discussion

Pressure sores occur most frequently in the elderly and the chronically ill, two groups that will continue to increase in number into the next century. The surgeon caring for patients with advanced, Grade III (extend- ing into the muscle) to Grade IV (involving the under- lying bone and/or joint) pressure sores must now balance several competing and, at times, contradictory demands. First, patients and their families reasonably expect that these sores will be treated in the most efIicacious and expeditious manner possible, which generally means surgical debridement and flap coverage. At the same time the surgeon practising in today’s cost-effective managed care environment is cognizant that surgical procedures are expensive and, while they are generally more cost-effective than prolonged non-surgical therapy for advanced sores, long-term recurrence rates following surgical procedures can exceed 50%.2

This study is one of the largest modern series of pressure sores involving the ischial area and, to our knowledge, is the largest series of inferior gluteal and gluteus maximus flaps reported. Unlike most previous studies, this series compares the efftcacy of one flap to another in providing reliable coverage of the ischial sore. Patients in this study were not randomized and the flaps selected undoubtedly reflect the biases of the surgeons involved. Nonetheless, this data represents the combined treatment by more than twelve attend- ing surgeons over a 17-year period and should thus be widely applicable.

Encouragingly, the data from this study indicates that most ischial pressure sores can be debrided and flap coverage provided in a single operation. This is true regardless of patient age, the number of wound healing risk factors they possess, the size of their pressure sore ‘and even the number of prior flaps. In fact, contraindications to performing immediate flap reconstruction involve only those patients in whom their ability to physiologically tolerate the operative procedure is in question (i.e. severe cardiopulmonary disease, sepsis, etc.).

In this study, the average length of bedrest following flap coverage and time of hospitalization was significantly shorter than in previously published reports, which suggests improvement in the overall cost-effectiveness of this approach. For example, in 1994 Rajacic et al.‘” reported the most recent notable series of inferior gluteus maximus island flaps for ischial coverage (31 flaps in 27 patients). Typical of other reports in the literature, their standard length of time for patients to be on bedrest postoperatively was 5 weeks and the average hospital stay was 40 days, but their flap success rate (100% at time of hospital discharge, 3 recurrent sores 6-13 months after surgery) was only slightly better than ours. In fact, although the patients in this study averaged 21 days of hospitalization, the trend has progressively been towards shorter hospital stays. Currently, patients are kept hospitalized for only 7-10 days and discharged home or transferred to appropriate care facilities if their wounds are healed at that time. This approach has not resulted in an increase in the short-term recurrence

rate. Postoperatively, any flap suture line breakdowns or non-healing areas which do not close within a few days are promptly treated with operative debridement and flap readvancement, since these wounds are relatively unlikely to heal otherwise. This approach should minimize patient morbidity and further decrease hospital costs. Prospective studies are needed to further define the optimum period of bedrest and postoperative mobilization, with appropriate facilities, following pressure sore flap procedures.

Historically, ischial sores have been the most difficult pressure sores to treat.” Motion over the ischial area, which is greater than with other pressure sore sites, and the pressure exerted on the region during sitting may help to explain why. Unlike the sacral and trochanteric areas, there are significant changes in the tension exerted across ischial sores with different posi- tioning of the legs. Based primarily on the immobile pelvis, the sacral sore has relatively constant forces across the wound. While trochanteric sores are based on the more mobile leg, changes in wound size (resulting from altered tension across the wound) occur only with internal or external rotation of the hip, a relatively infrequent event, particularly in the paraplegic or chronically ill patient. In contrast, for the ischial sore, any alteration in leg position, particularly flexion or extension, produces tension and a change in wound size. To minimize this tension following ischial sore coverage, we reasoned that flaps based on the (immobile) trunk or pelvis should perform better in the coverage of ischial sores than those based on the more mobile lower extremity. In fact, there are two frequently used flaps for ischial sores which may be thought of as based in the pelvis: the inferior gluteus maximus myocutaneous flap and the inferior gluteal thigh flap. The inferior gluteus maximus flap is based entirely in the pelvic area. The inferior gluteal thigh flap can be considered pelvic-based since its pedicle, the descending branch of the inferior gluteal vessels, originates in the pelvis and the connections of the inferior gluteal thigh flap to the leg are completely severed during inferior gluteal thigh island flap eleva- tion. In this study, success rates when the inferior gluteus maximus and inferior gluteal thigh flaps were used for ischial sores coverage were 94% and 93%, respectively.

The inferior portion of the gluteus maximus muscle along with an island of overlying skin seems to be the best choice for initial coverage of an ischial pressure sore. First reported in 1979 by Mathes and Nahai’ and later modified by Scheflan et a1.15 and Stevenson et a1.,16 this flap can provide a large area of soft tissue for transposition, the reported donor site morbidity is low,” and, contrary to a common misperception,” the descending branch of the inferior gluteal artery, the major blood supply to our flap of second choice (the inferior gluteal thigh flap), is routinely preserved. Even after division of this vessel, however, we and others have found that the inferior gluteal thigh flap remains reliably vascularized, presumably due to the collateral vessels from the thigh.18 Although it has proven quite successful in our patients, the inferior gluteal thigh flap is felt to be slightly less optimal for ischial sores since it provides no muscle, it lacks bulk, and it is subject to slightly more shearing and tension

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forces due to its location on the (mobile) leg. Like the inferior gluteus maximus, use of the inferior gluteal thigh flap preserves other flap options, although a subsequent hamstring flap would require a skin graft for coverage once the inferior gluteal thigh flap had been used. Both the inferior gluteus maximus and the inferior gluteal thigh flap are highly reliable (no flaps lost in this series) and provide enough of a skin island that flap readvancement is usually possible in cases of small wound separations or recurrences, thereby preserving future flap options. This order of flap preference would be reversed in the ambulatory patient. We have found that sacrificing the inferior half of the gluteus muscle does not create a significant functional deficit when this muscle flap is used for either pressure sore coverage or as a free flap in breast reconstruction.‘9

Several popular flap options for ischial coverage, the tensor fascia lata and the V-Y hamstring flaps, proved unreliable in this study due to problems with flap vascularity and wound separation, respectively. The tensor fascia lata flap is simply not reliable enough in the distal 6-S cm of the flap (the area adja- cent to the knee) and this distal portion of the flap is critical for ischial coverage. Thus, if a tensor fascia lata flap must be used for ischial sore coverage, it should be delayed*O or an expander used to enhance vascularity of the distal tip.

While V-Y flaps do well for sacral and trochanteric sore coverage (where the V-Y gluteus maximus and V-Y tensor fascia lata flaps are our flaps of choice, respectively), all V-Y flaps are intrinsically limited in their advancement by the length of the supplying pedicle. While this advancement seems to be enough to treat successfully the less mobile sore areas, the V-Y hamstring flap does not seem adequate, at least in this study, to treat successfully ischial sores since its success rates fall far below the other flaps in common use. In addition, the V-Y hamstring is based solely on the leg and, as described previously, the greater tension inher- ent in leg-based flaps seems a particular problem with this flap. While it is conceivable that our rapid mobilization of patients within a few weeks of surgery may have contributed to the failures of the V-Y hamstring, the identical programme was followed for all patients and did not seem to have any deleterious effects on the other flaps used in this study.

In cases where the inferior gluteus maximus and inferior gluteal thigh flaps are not available, other options include the gracilis flap for smaller wounds and the rectus abdominis flap (tunelled through the groin). The expanded or delayed tensor fascia lata flap and the V-Y hamstring flap should be used prior to considering leg amputation and thigh flap coverage (Table 4).

This study did not attempt to address recurrence rates following surgical treatment. Other authors have attempted to define subsets of patients with high recurrence rates, in an effort to select those who will most benefit from surgical treatment of their sores. In our study, many patients previously felt to be relatively poorer candidates for surgery (including smokers, diabetics, patients with renal failure, low total protein, etc.) did not differ significantly in their healing rates

Table 4 Flap selection for ischial pressure sore coverage

Relative prejbence

Inferior gluteus maximus island flap

Inferior gluteal thigh flap

V-Y hamstring Tensor fascia lata (expanded or delayed) Rectus abdominis Gracilis*

*Limited to small, relatively superficial defects (< 40 cm2).

from patients lacking these potential risk factors. Based upon our experience, psychosocial factors would seem to play a more important role than medical factors in predicting sore recurrences. Patients suffering from pressure sores are obviously unfortu- nate, those with recurrences doubly so. Hopefully the data and resultant flap selections presented here will aid the practising surgeon in achieving optimum rates of healing while preserving the maximum number of future flap options.

Acknowledgement The authors would like to thank Robin Turner for his statistical analysis of our data.

References

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2. Disa JJ, Carlton JM, Goldberg NH. Efftcacy of operative cure in pressure sore patients. Plast Reconstr Surg 1992; 89: 272-8.

3. Mathes SJ, Nahai E Clinical atlas of muscle and musculocutaneous flaps. St Louis: Mosby, 1979: 91-104.

4. Hurwitz DJ, Swartz WM, Mathes SJ. The gluteal thigh flap: a reliable sensate flap for the closure of buttock and perineal wounds. Plast Reconstr Surg 1981; 68: 521-5.

5. Hurteau LE, Bostwick J, Nahai F, Hester R, Jurkiewicz MJ. V-Y advancement of hamstring musculocutaneous flap for coverage of ischial pressure sores. Plast Reconstr Surg 1981; 68: 53944.

6. Tobin GR, Sanders BP, Man D, Weiner LJ. The biceps femoris myocutaneous advancement flap: a useful modification for ischial pressure sore reconstruction. Ann Plast Surg 1981; 6: 396401.

7. Nahai F, Hill HL, Hester TR. Experiences with the tensor fascia lata flap. Plast Reconstr Surg 1979; 63: 788893.

8. Wingate GB, Friedland JA. Repair of ischial pressure ulcers with gracilis myocutaneous island flaps. Plast Reconstr Surg 1978; 62: 245-50.

9. Bunkis J, Fudem GM. Rectus abdominis flap closure of ischiosacral pressure sore. Ann Plast Surg 1989; 23: 447-9.

10. Royer J, Pickrell K, Mladick R, Georgiade N, Thorne E Total thigh flaps for extensive decubitus ulcers: a I6-year review of 41 total thigh flaps. Plast Reconstr Surg 1969; 44: 109918.

11. Griffith BH, Schultz RC. The prevention and surgical treatment of recurrent decubitus ulcers in patients with paraplegia. Plast Reconstr Surg 1961; 27: 248-60.

12. Riou JA, Cohen JR, Johnson H. Factors influencing wound dehiscence. Am J Surg 1992; 163: 32430.

13. Evans JM, Andrews KL, Chutka DS, Fleming KC, Garness SL. Pressure sores: prevention and management. Mayo Clin Proc 1995; 70: 789-99.

14. Rajacic N, Gang RK, Dashti H, Behbehami A. Treatment of ischial pressure sores with an inferior gluteus maximus musculocutaneous island flap: an analysis of 31 flaps. Br J Plast Surg 1994; 47: 4314.

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15. Scheflan M, Nahai F, Bostwick J. Gluteus maximus island musculocutaneous flap for closure of sacral and ischial ulcers. Plast Reconstr Surg 1981; 68: 533-8.

16. Stevenson TR, Pollock RA, Rohrich RJ, Craig AV The gluteus maximus musculocutaneous island flap: refinements in design and application. Plast Reconstr Surg 1987; 79: 761-8.

17. Cheng TJ, Tang YB. Treatment of ischial pressure sores with an inferior gluteus maximus musculocutaneous island flap [letter]. Br J Plast Surg 1995; 48: 521-2.

18. Rubin JA, Whetzel TP, Stevenson TR. The posterior thigh fasciocutaneous flap: vascular anatomy and clinical application. Plast Reconstr Surg 1995; 95: 1228-39.

19. Codner MA, Nahai E The gluteal free flap in breast reconstruction: making it work. Clin Plast Surg 1994; 21: 289-96.

20. Zuffrey J, Doerfl J, Krupp S. The anatomical basis for delaying the musculocutaneous tensor fascia lata flap with a distal extension. Eur J Plast Surg 1988; 11: 109916.

The Authors Robert D. Foster MD, Fellow James F’. Anthony MD, Associate Professor Stephen J. Mathes MD, Professor and Chairman William Y. Hoffman MD, Associate Professor Division of Plastic and Reconstructive Surgery, University of California at San Francisco, San Francisco, California, USA.

Correspondence to James l? Anthony MD, Division of Plastic and Reconstructive Surgery, University of California at San Francisco, 1635 Divisadero Street #530, San Francisco, CA 94115-1632, USA.

Paper received 23 September 1996. Accepted 17 February 1997, after revision.