Extraarticular fluid dissection in tissues during arthroscopy

Abstract

Significant fluid extravasation occurred in four knees undergoing arthroscopic meniscectomy. In one knee, a partial compromise of peripheral blood flow was transiently detected.

In cadaver studies, with the joint only moderately distended, a mean pressure of 158 mm of mercury was measured. With flexion of the knee to 90°, a mean pressure of 216 mm of mercury was recorded and rupture of the synovial pouch occurred in all knees. The fluid extravasated into the thigh due to rupture of the suprapatellar pouch. Fluoresceine labeled saline was utilized to follow the course of the extravasated fluid. The saline was found to loculate about the superficial femoral artery, easily dissecting up to the femoral triangle. Elevated femoral artery pressures and quadriceps muscle interstitial pres sures were documented at a relatively early point during the course of fluid extravasation. A second pathway of extravasation of intraarticular fluid was by rupture of the semimembranous bursa. The saline then dissected beneath the pes anserinus and into the calf muscles.

The study arrived at the following conclusions. First, fluid extravasation may initially occur in a subtle man ner. The surgeon should be aware of any lack of joint distension, increased fluid to distend the joint, or increased thigh tension during arthroscopy indicating extravasation. Second, joint distension should be avoided prior to knee flexion past 30 to 45° since the added compression on the fluid may easily rupture the synovial pouch. Third, caution is required in using inflow irrigation systems that exert pressure to distend the joint; an adequate outflow system is mandatory to avoid excessive joint distension during arthroscopic procedures.