Intra-articular psoas tendon release alters fluid flow during hip arthroscopy

While not proven definitively, the hypothesis that intra-articular psoas tendon release allows fluid to track into the retroperitoneal space has been widely accepted. This study attempts to identify the path through which fluid enters the pelvis and retroperitoneal space. Six hemi-pelvis human cadaveric specimens were utilized for this study. 3 specimens underwent a capsulotomy and psoas tendon release, while 3 had only a capsulotomy. Arthroscopy fluid was combined with Barium and Methylene blue, and fluid was run at 50 mmHg for 2 hours. A gross dissection was performed at the end of the arthroscopy and the path of fluid flow into the pelvis and throughout the thigh was identified. All 6 specimens showed extravasation of fluid into the pelvis at the 5 minute mark. Specimens with a psoas tendon release showed an altered pattern of fluid flow. In all three of these specimens, the psoas muscle belly was bright blue, along with the remaining tendon. Two of the 3 specimens showed tracking of fluid along the vasculature in both directions. The volume of fluid tracking into the pelvis was increased following a psoas release. Arthroscopy fluid rapidly enters the pelvis following the initiation of hip arthroscopy, regardless of the status of the psoas tendon. Release of the psoas tendon allows fluid to diffuse into the psoas muscle and anterior medial thigh, tracking both proximally and distally along the neurovascular structures, and the volume of fluid tracking into the pelvis is increased following a psoas release.