Session VII Pelvis and Acetabulum

The Effects on the Abductor Muscles of Surgical Approaches for Acetabular Fractures with Associated Gluteal Vascular Injury

Owen B. Tabor, MD, Michael J. Bosse, MD, K. G. Greene, BS, H. E. Gruber, PhD, K. Kaysinger, PhD, S. H. Sims, MD, S. R. Blumenthal, PhD, J. F. Kellam, MD

Complex acetabular fractures are often managed surgically via extensile approaches that tether the abductor mass on a superior gluteal artery and vein (SGA/SGV) based pedicle. Previous reports of human cadaver studies concluded that the extensile approaches eliminate abductor collateral circulation and may cause ischemic necrosis if used in the presence of SGA injury. This study examined the in-vivo viability of the abductor muscles following extensile exposures to the pelvis in the presence of SGA or SGV injury.

Twenty-two dogs underwent either an extensile (extended iliofemoral, triradiate or modified extensile) or combined (Kocher-Langenbeck and iliofemoral) acetabular approach. Dogs were given SGA, SGV or no vessel ligation. Blood flow to the affected gluteal region was evaluated pre- and postoperatively and at 6 weeks by angiography, laser Doppler flowmetry (LDF) and fluorescent microspheres. Histologic and wet weight analysis was performed on the abductor muscles with contralateral comparison control 6 weeks postoperatively. Of the 17 dogs with extensile exposures, 7 had SGA ligation, 7 had SGV ligation and 3 had no vessel disruption (controls); 5 dogs had combined approaches (4 SGA, one control).

In no specimen was the abductor flap completely devascularized. Dogs undergoing extensile exposures after SGA ligation had a significant loss of abductor muscle mass (-41%, P<0.001), decreased postoperative perfusion by microsphere analysis (-47%, P<0.01), and histologic evidence of moderate to severe necrosis in 5/7 specimens (P=0.01). Extensile exposure and SGV ligation also caused a significant loss of muscle mass (-25%, P<0.02) with moderate to severe necrosis occurring in 4/7 specimens (P<0.04). Dogs with SGA ligation undergoing the two-incision approach had non-significant changes in muscle mass (-3%), perfusion by microsphere and LDF analysis, and moderate to severe necrosis in only 1/4 specimens. Control dogs with extensile exposures also had no significant changes in the abductor mass by weight, perfusion or histologic analysis.

In the presence of gluteal vascular injury in this atraumatic canine model, none of the approaches caused complete ischemic necrosis in any of the tested specimens. Extensile approaches caused significant abductor devascularization at 6 weeks. The combined approach caused minimal changes. Until the long-term recovery response of the abductor muscle can be defined, a surgical technique that preserves collateral circulation should be considered for patients requiring exposure of both columns in cases of suspected or confirmed gluteal vascular injury.