The Posterior Thigh Flap for Ischial Pressure Sores

We read with great interest the article of Lin et al on the reconstruction of ischial pressure sores with the laterally based posterior thigh flap (PTF).[1] Despite the ongoing progress of pressure sore prevention and treatment, this problem remains difficult to solve. The ischium is the most frequent site of pressure sore occurrence, due in part to increased pressure exerted on the region during sitting and in part to motion over the ischial area.[2] Recurrence rates after pressure sore reconstruction (>50% in the long term) have remained largely unchanged during the past 40 years. Therefore, a rationale for flap coverage designed to treat a patient during the long term is necessary from the time of initial evaluation.[2] Despite high rates of flap survival, not all flaps are equally reliable in achieving coverage of the debrided pressure sore wound. Therefore, the most important step for early treatment success is appropriate flap selection, leaving the other possible options for repair undamaged.[2]

Although the PTF for reconstruction of ischial pressure sores proves an excellent option, our feeling is that it is underestimated when choosing a flap for ischial pressure sores. We support the opinion of Lin et al that it should be used more frequently because it preserves several advantages: it is a reliable flap; it preserves adjacent cutaneous territories; it spares underlying muscle; and readvancement of the flap is possible in cases of recurrent or adjacent sores. Furthermore, it is suitable for patients who walk because it will not leave a functional defect.

The PTF was reported for treatment of larger defects localized in the sacrum, perineum, and even trochanteric area.[3] [4] These advantages are further enhanced by the characteristics of vascularization of the PTF, which has a major contribution from the first and second profunda perforators. Even when the descending branch of the inferior gluteal artery is severed, the PTF can still be elevated based on the cruciate anastomosis (between the descending branch of the inferior gluteal artery and the profunda perforators) previously underlined by Rubin et al.[3] However, we would like to make few remarks.

Lin et al depict in the text a design of the PTF that closely resembles the flap proposed by Rubin et al[3] (based mainly on the first and second profunda perforators and the inferior gluteal artery), and the flap shown in Fig. 1 of Lin and colleagues’ article resembles the flap proposed by Hurwitz et al.[4] The PTF, as shown in Fig. 1, has a rather high pivot point and would hardly include the first and second profunda perforators as a vascular source. Thus, the flap in Fig. 1 closely resembles the gluteal thigh flap[4] and/or the pedicled PTF used by Paletta et al[5] in two cases. However, all these designs of the PTF were shown to be reliable and efficient despite their varieties in construction and main source of vascularization.[2] [3] [4] [5]

Lin et al state that all defects in their series were grade IV. However, in such deep defects, when ostectomy is commonly required, muscle flap would be necessary to fill the defect. We feel that the PTF can be used in ischial pressure sores of grade III and IV but when the defect is too deep, the fasciocutaneous flap might not be sufficient to fill it adequately. A space is left between the bottom of the defect and the flap, which can cause fluid collection and recurrence, despite adequate drainage. In such cases, we prefer filling the cavity with muscle such as the hamstring flap or the inferior gluteus maximus muscle or musculocutaneous flap. This would not preclude the use of PTF in deep defects, but prior careful evaluation as to potential residual cavity seems reasonable.

In conclusion, we feel that the PTF should be considered among the first-line treatment options for ischial pressure sores after a careful preoperative analysis. We would like to thank Drs Lin et al for their interesting contribution to solving this difficult problem.

REFERENCES

• 1 Lin H, Hou C, Chen A, Xu Z. Long-term outcome of using posterior-thigh fasciocutaneous flaps for the treatment of ischial pressure sores.  J Reconstr Microsurg. 2010;  February 24 (Epub ahead of Print]
• 2 Foster R. Pressure sores. In: Mathes S, Hentz V R, eds. Plastic Surgery. Philadelphia: Saunders Elsevier; 2006: 1317-1355
• 3 Rubin JA, Whetzel TP, Stevenson TR. The posterior thigh fasciocutaenous flap: vascular anatomy and clinical application.  Plast Reconstr Surg. 1995;  95 1228-1239
• 4 Hurwitz D J, Swartz W M, Mathes S J. The gluteal thigh flap: a reliable, sensate flap for the closure of buttock and perineal wounds.  Plast Reconstr Surg. 1981;  68 521-532
• 5 Paletta C, Bartell T, Shehadi S. Applications of the posterior thigh flap.  Ann Plast Surg. 1993;  30 41-47