Correlation between the number of perforators, flap dimensions and the incidence of venous congestion in reversed flow posterior interosseous artery flap

Abstract

The reversed flow posterior interosseous artery flap is a valuable option in the reconstruction of hand defects. The flap offers an expandable solution and has many advantages over other regional and distant flaps. It is reliable, with many lifeboats in case of failure. Despite that, it did not gain the popularity expected due to its tedious dissection and the associated problem of venous congestion. This prospective comparative work aimed at studying the effect of number of perforators included and the flap dimensions over the incidence of venous congestion to help overcome this problem. This study was conducted on fourty patients in Ain Shams University and Ahmed Maher Teaching hospitals. These patients had different hand defects due to different etiological factors. All patients hand defects were reconstructed by the reversed flow posterior interosseous artery flap and were divided equally according to the number of perforators and the size of flaps into the following groups:- Group Ia (10 patients): flaps with one perforator included and the size of the flap is less than 40 cm2. Group Ib (10 patients): flaps with one perforator included and the size of the flap is more than 40 cm2. Group IIa (10 patients): flaps with more than one perforator included and the size of the flap is less than 40 cm2. Group IIb (10 patients): flaps with more than one perforator included and the size of the flap is more than 40 cm2. Previous studies showed that the posterior interosseous artery was a constant finding except for minimal number of cases (1.5%) in few studies. In agreement with our study, the artery was not found in one case only. The anastomosis between the anterior interosseous artery and the posterior interosseous arteries which carries the blood supply to the reversed flap was a constant finding in all previous literature except for one author. In this study the anastomosis was consistent. The original authors Zancolli and Angrigiani mentioned that the flap can reach up to the level of the heads of the metacarpals. Several modifications were done to increase the reach of the flap later on. In our study the flap reached up to the dorsum of the distal phalanx, ulnar side of the hand and the volar side of the hand. In our study the increase in distal reach of the flap is attributed to the inclusion of the perforator of the recurrent branch of the posterior interosseous artery in the flaps that were elevated from skin just below the elbow and also dissection of the anastomosis between the anterior and the posterior interosseous arteries. In this study, 62.5% of cases passed uneventful. 32.5% of cases suffered venous congestion with mild venous congestion and complete flap survival in 7.5%, moderate venous congestion and partial flap loss in 17.5% and severe venous congestion with total flap loss in 7.5%. Ischemia with complete flap loss occurred in 5% of cases. Based on the results of this study, it is not recommended to raise the flap on the maximum number of perforators included as previously thought. In small flaps with surface area less than 40 cm2, the design should include only one perforator to avoid flap congestion and its sequel. The most consistent perforator is the most proximal relevant perforator (MPRP) of the posterior interosseous artery that should be included in the flap. The most proximal relevant perforator lies about 6.1-11.9 cms from the lateral epicondyle. Similarly flaps may be raised on only one perforator in large flaps up to 80 cm2 with good blood inflow and outflow and lower rate of complications. Regarding the size of the flap and its effect on the incidence of venous congestion, it was proved statistically that the congestion was not affected by the surface area, the length or the width of the flap, and so the number of the perforators is the only variant that relates to the incidence of venous congestion if the PIA flaps.