Acute abdomen as complication of a knee arthroscopy: A case report

A knee arthroscopy in spinal anaesthesia was performed on a 67 years old male patient. During the procedure the patient was hemodynamically stable, until he suddenly turned pale and started complaining of severe pain in lower abdomen with signs of guarding. The procedure was fi nished as urgently as possible and after releasing the tourniquet we noticed signifi cant diff erence in volume of the leg, with redness distal to tourniquet. Urgent lab results were essentially unremarkable and the patient was sent for the urgent radiological diagnostics.


Introduction
Knee arthroscopy is a safe operation technique with approximately 1% complication rate [1]. The most common are pyogenic arthritis, deep vein thrombosis and pulmonary embolism [1]. Fluid extravasation is expected in subcutaneous tissue and around entry portals for arthroscopic tools. In our case, extravasation of irrigation luid happened in upper thigh, scrotum, retroperitoneal and intraperitoneal space, despite the in lated tourniquet. There are only a few available cases in literature, where the extravasation of the irrigation luid was mostly limited by in lated tourniquet or was present only below the knee [2,3].

Case presentation
67 years old male patient was taken for a knee arthroscopy for his gonarthrosis. He had a history of hyperlipidaemia and enlarged prostate. He had surgery for protrusion of the intervertebral disc L4-L5 and bile surgery 40 years ago. His body mass index (BMI) is 28.4 kg/m 2 .
The procedure was made under spinal (subarachnoid) anaesthesia. Arthroscopy was made with a pressure pump with pressure of 50 mmHg.
During the procedure he was hemodynamically stable, towards the end of the procedure he suddenly turned pale and started complaining of severe pain in the lower abdomen on the left side; clinically developing signs of guarding. Nasogastric tube was placed, only the gastrointestinal-bile contents were obtained in trace amounts. Hemodynamically he was still stable (140/80 mmHg). Tourniquet was working for 45 minutes before onset of described symptoms.
The procedure was completed as quickly as possible. After releasing the tourniquet, initially set at 250 mmHg, a signi icantly larger volume of the left leg was noted when compared to the right one, and there was redness distal to the tourniquet position. Urgent radiological diagnostics was requested with a differential diagnosis of hollow organ rupture or thromboembolic event. Abdominal X-ray in lateral decubitus position and Colour Doppler (CD) of the left leg showed luid in the soft tissues of the thigh, scrotum, and abdomen; non enhanced and contrast enhanced, venous phase computed tomography (CT) of the abdomen and pelvis showed a free luid along the entire left thigh around the femoral shaft, extending towards the scrotum, gluteal region, into the pelvis, and into the abdomen. Fluid was present in the perihepatic and perisplenic spaces with gas bubbles in the left retroperitoneum and anterior aspect of the left thigh.
He was admitted to the Intensive care unit (ICU) for noninvasive monitoring: blood pressure (BP) 120/80, pulse 70/ min, SpO2 99%, breathing frequency (BF) 19/min. Heart and lung sounds were normal, abdomen was painless, and peristalsis was audible. Left foot was oedematous with good peripheral pulsation, right foot was unremarkable.
He was hemodynamically stable, excess luid was resorbed and excreted by stimulated diuresis and all of the symptoms resolved within a few hours after the surgery. In the end it turned out that symptoms of acute abdomen were caused by accumulation of luid in abdomen cavity and retroperitoneum. The patient was transferred to the ward the following day and his postoperative course was uneventful, without further complications.

Discussion
We hadn't had a complication like the one we described here, so we consulted all available literature to determine the cause. The available literature shows only a few similar cases, of which most of them did not use the tourniquet at all [2,3]. In most of other described cases, there was a compartment syndrome distal to the site of the tourniquet [4,5]. Abdominal extravasation of irrigation luid was mostly described after hip arthroscopy [6].
As the symptoms of acute abdomen occurred, we tried to visualise if there is any sign of knee capsule rupture, or any sign of some other complication, but we couldn't visualise it with arthroscope. Scrub nurse observed sudden larger saline consumption by the pump, but the pump stated the same pressure set on the beginning of the procedure, so the real cause of the symptoms was not con irmed. We checked arthroscopic pump and all parts of tourniquet formal functions, but we couldn't ind any, all parts of the equipment passed the control.

Conclusion
Inclusive; this complication was presumably caused by a ruptured knee capsule, although we couldn't see it with arthroscope nor imaging tests, but since both radiographic methods described both liquid and gas within the leg proximally of the knee capsule and within the abdomen, it is the only conclusion we could make. In most cases in literature, the main cause of luid extravasation was rupture of the capsule caused by a pressure sensor failure [2,3,7].
Whether the cause of the rupture is a faulty arthroscopic pump or something else, we cannot say with certainty (both were tested after the procedure, but we didn't ind any malfunctions).
We learned that this might have been avoided if we monitored liquid balance all the time during the procedure (output should be almost equal as input) in arthroscopy more closely; therefore, we would recommend it as one of the safety measures.
In our opinion, it was fortunate we performed this arthroscopy in spinal (subarachnoid) anaesthesia, because the patient was awake and could alert us of something unexpected happening; should general anaesthesia been used, the consequences would probably be worse due to larger amount of luid which would have been used before anything would have been noticed.