Contralateral psoas hematoma after minimally invasive, lateral retroperitoneal transpsoas lumbar interbody fusion: a multicenter review of 3950 lumbar levels.

OBJECTIVE Minimally invasive lateral lumbar interbody fusion (LLIF) via the retroperitoneal transpsoas approach is a technically demanding procedure with a multitude of potential complications. A relatively unknown complication is the contralateral psoas hematoma. The authors speculate that injury occurs from segmental vessel injury at the time of contralateral annulus release; however, this is not fully understood. In this multicenter retrospective review, the authors report the incidence of this contralateral complication and its neurological sequelae. METHODS This study was a retrospective chart review of all minimally invasive LLIF performed at participating institutions from 2008 to 2014. Exclusion criteria included an underlying diagnosis of trauma or neoplasia as well as lateral corpectomies or anterior column releases. Single-level, multilevel, and stand-alone constructs were included. All patients underwent preoperative MRI. Follow-up was at least 12 months. All complications and clinical outcomes were self-reported by each surgeon. RESULTS There were 3950 lumbar interbody cages placed via the retroperitoneal transpsoas approach, with 7 cases (0.18% incidence) of symptomatic contralateral psoas hematoma, 3 of which required reoperation for hematoma evacuation. Neurological outcome did not improve after reoperation. Reoperation occurred an average of 1 month after the initial operation due to a delay in diagnosis. In 1 case, segmental artery injury was confirmed at the time of surgery; in the others, segmental vessel injury was suspected, although it could not be confirmed. Neurological deficits persisted in 3 patients while the others remained neurologically intact. Two patients were receiving antiplatelet therapy prior to the procedure. CONCLUSIONS The contralateral psoas hematoma is a rare complication suspected to occur from segmental vessel injury during contralateral annulus release. Detailed review of preoperative imaging for aberrant vessel anatomy may prevent injury and subsequent neurological deficit.