The Use of CO 2Instead of Fluid in Arthroscopic Anterior Cruciate Ligament Reconstruction

Introduction

During arthroscopic anterior cruciate ligament (ACL) reconstruction, adequate visualization of joint structures is usually achieved by injecting a fluid to distend the joint space. In such cases obscuration by the synovial villi, hemorrhage, and detached particles may cause additional surgical difficulty. Moreover, recent demanding skills as femoral tunnel placement or meniscal suturing require a view that is as realistic as possible. An alternative to enhance arthroscopic visualization during ACL reconstruction is to use a gas to distend the joint. Possibly due to previously reported incidents, this technique remains a very rare practice among orthopaedic surgeons despite acknowledged benefits.

Body

Birscher used gas insufflation during the first arthroscopic joint explorations in 1921. Henche, in the 1970s, popularized the use of gas which became the rule during the 1980s, until the injection of air at high pressure generated two cases of fatal gas embolism. At the same time, several cases of expensive emphysemas were reported, and therefore the use of gas remained a very rare practice among orthopaedic surgeons, although systemic complications such as gas embolism have never been reported when using CO ₂insufflation in the knee joint.

On the flip side, these serious adverse event reports and their analysis allowed researchers to better codify the use of CO ₂as medium, avoiding the use of air, which is 6 times less soluble in blood than CO ₂, using low pressure CO ₂insufflation (50 mmHg) and a tourniquet applied to the calf. Under these conditions, its use in the 1990s for laser arthroscopic surgery reported no serious adverse experiences attributable to gas insufflation. Moreover, a recent study showed no significant increase of CO ₂blood diffusion when using gas instead of fluid during ACL reconstruction surgery, and a rate of only 6.2% minor subcutaneous emphysema with spontaneous and rapid regression.

Surgical Technique ( )

The use of gas (CO ₂) does not exempt the use of fluid to rinse the joint if necessary and to cool motorized and heat-generating devices such as a shaver blade or tissue vaporization systems. The use of gas requires an arthroscope with two entry sites: one for gas and one for fluid ( Fig. 60.1 ). When knee joint washout is required, gas entry is closed and fluid is supplied with a simple gravity-fed irrigation system (see Fig. 60.1 ). Once the rinsing is complete, fluid entry is closed and gas entry reopened. The fluid can be evacuated directly by the shaver connected to the suction tubing of the operating room or eventually through a simple cannula.

A modified laparoscopic insufflator can be used to fill the knee joint with gas at a pressure of 50 mmHg (see Fig. 60.1 ). The motorized shaver can be used for the resection of synovial tissue and ACL remnants with gas for short periods and with fluid when needed for more than 2–3 minutes, to avoid overheating the shaver blade.

From the economic point of view, the gas does not avoid the need for washing out but the quantity of fluid is significantly reduced (less than 1 L for a meniscus resection and less than 3 L for an ACL reconstruction). This can easily be achieved without an expensive pump and tube systems by using a simple gravity-fed irrigation system. Moreover, a specific arthroscopy sheet with a pouch or suction system to collect the fluid from the floor is unnecessary.

Tips and Tricks

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Standard arthroscopic incisions should not be too extensive, to avoid gas leakage through the incision site with possible loss of joint dilatation. The use of a #11 scalpel blade is recommended.
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Blood or synovial fluid joint effusion requires washout with saline or water prior to CO ₂insufflation.
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The soiling of the lens by blood or synovial fluid and its fogging by evaporation can be managed by carefully wiping the lens on intra-articular surrounding soft tissues, such as synovial villi or the fat pad. This maneuver thus avoids leaving the arthroscope from the joint for cleaning the lens.
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As light is less absorbed by gas than by fluid, the brightness of cold light must be adapted to avoid abnormal reflections when using gas, especially the more glossy appearance of anatomical structures.
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During ACL reconstruction, the shaver is very useful in extracting liquid before refilling the joint with CO ₂. There is then no need to reintroduce and remove the cannula during this maneuver.

Benefits of Gas Distension ( )

The most frequently reported benefits when using gas arthroscopy are a more realistic visualization of joint structures, an increased field of view, and the avoidance of reduced visibility due to bleeding, synovial villi, and floating debris ( Fig. 60.2 ). This superior visibility improves the assessment of associated meniscus ( Fig. 60.3 ) and cartilaginous lesions ( ) or partial ACL tears and facilitates precise surgical procedures as placement of the femoral tunnel, as it allows for an excellent view of the intercondylar notch ( Fig. 60.4 ). In fact, during ACL reconstruction, the use of gas is very helpful for the notch preparation that generates many floating particles when using fluid ( ). The femoral tunnel aiming is recognized as technically difficult. Indeed, the lateral wall of the notch is oriented in a sagittal plane, and the workspace is considerably reduced when the knee is flexed at 120 degrees. A realistic vision of the anatomy of the lateral notch with the optic introduced in the anteromedial portal is one of the main keys of ACL reconstruction ( Fig. 60.5 ). As a result, from the combination of increased field of view, greater luminosity, and enhanced color definition, anatomical structures such as the lateral intercondylar ridge and the lateral bifurcate ridge can be more easily recognized. The femoral remnant fibers of the two bundles of ACL, flattened in gas medium, do not need a complete shaving to clear the lateral wall of the notch vision, and can be used as valuable landmarks. Finally, the lack of soft tissue swelling by extravasation of fluid enables for easier secondary procedures such as anterolateral reinforcement and other extra-articular ligament reconstructions.