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Arthroscopy's 3 Hidden Advances
These features have greatly benefited minimally invasive joint repair.
Eloy Ochoa Jr
Publish Date: July 9, 2015   |  Tags:   Orthopedics
arthroscopic visualization IS IMAGE EVERYTHING? Arthroscopic visualization depends on fluid insufflation as well as optics, says orthopedic surgeon Eloy Ochoa Jr., MD.

Professional athletes and ordinary folks alike have hailed the arthroscopic cameras, shavers and other tools that make minimally invasive joint repair possible as a medical miracle. And high-definition imaging has given us unparalleled views of the musculoskeletal anatomy we're diagnosing and treating. But some of the field's most useful improvements in recent years are to be found in far less flashy devices and features. Here's a user's-eye-view of 3 underappreciated advances that have made a big difference to arthroscopic surgery.

1. Finer fluid management
Arthroscopic efficiency is a fluid issue, and I mean that literally. From visualizing the surgical site to trimming torn tissue, fluid management plays an extremely important — and often underappreciated — role in arthroscopy. It's even possible that its components have seen more significant technical advances in recent years than our miniaturized cameras and high-definition monitors have.

The joint is a collapsed space. To perform arthroscopic examination or treatment on it, one of our first tasks is insufflation. Expanding the space provides us with the necessary exposure to achieve a clear view of the joint and insert and operate our instruments.

While CO2 gas or air are effective for insufflating the abdominal cavity, a steady flow of saline solution is preferred for expanding a joint. Historically, we'd hung 5 liter bags of the irrigation fluid on an IV pole and relied on gravity to feed the contents down through IV tubing into the joint. Occasional strategic raisings and lowerings of the bags on the poles let us control the inflow pressure. Managing the outflow was catch-as-catch-can with suction and absorbent materials on the floor.

The development of mechanical arthroscopy pumps has automated this process, however, and brought an internal benefit as well. They've proved to be an effective method of keeping the joint open, and they don't require your circulating nurse to interrupt her duties to keep a close eye on or routinely switch out bags of fluid. They help to maintain a consistent pressure in the joint, something that can be a struggle to accomplish with bags and gravity.

arthroscopy pump INFLOW AND OUTFLOW The ideal arthroscopy pump should be able to maintain a designated fluid pressure in the joint, and keep up with the addition of instruments or outflow of fluid.

Under the right conditions, this consistent pressure can also serve as a tamponade against intraoperative bleeding in the joint. During arthroscopy, your visualization can be obscured by just a few drops of blood, and even the most advanced HD camera will do you no good if you can't see. A pump that keeps the fluid pressure just above that of main arterial pressure works just like a mini tourniquet. It tamponades the vessels to keep runaway bleeding in check.

Newer models of pumps feature a dynamic fluidic system in which the inflow can automatically adjust to and balance the pressure against a changing outflow. The more jobs you're undertaking during an arthroscopy, the more important this becomes. If you're just taking pictures, consistent pressure is all you'll need. But if you're working with a shaver, for instance, which has its own suction, you're draining more fluid and potentially having to maintain a turbulent flow and the Bernoulli effect — that is, when the speed of horizontal flow through a fluid increases, the pressure decreases.

A dynamic fluidic system is more efficient. It helps to keep the fluid in the joint clean, which means better visualization — ?as opposed to waiting through the "red-outs" described above — which means shorter cases. Poor visualization from less effective pumps can make a 1-hour case much, much longer.

It's also safer. The knee joint is a capsule, a closed system, and will not experience a large amount of swelling with insufflation. In contrast, the shoulder is not closed, and the quality of soft tissue there is more prone to increased, painful swelling over time. Dynamic fluid pressure reduces the risk of extravasation and subsequent post-operative complications.

Over the past several years, the utility of these pumps has become as essential as high-definition imaging. There are a number of different commercially available systems to choose from, and every physician has his favorite. Ask around and you'll find that there are two key factors on which they've made their decisions.

First, is the pump able to maintain the pressure settings they chose, throughout the case? They want free-flowing fluid without fluctuation, that's clear and easy to see through. As soon as fluid is suctioned out, it should be replaced. Second, is it able to keep up when different instruments (with their own suction functions) are introduced into the site? Sensors should be able to register and regulate these changes, so you don't have a rapid extraction of fluid that can negatively impact exposure and visualization.

arthroscopic access ports NO LOOSE ENDS Handling and tying sutures through arthroscopic access ports requires trained hands, or implantable solutions.

2. More cooperative cameras
A physician's choice of arthroscopy camera system is more often than not based on the quality of the image it delivers to your OR's flat-screen display monitors. Cameras with high-definition resolution and three-chip technology have revolutionized the field with the amount of information they capture, and competing manufacturers' one-upmanship upgrades every few years give users plenty to think about. Running a close (or distant, depending on who's buying) second is the price of the technology.

But the big picture isn't the only advance that has made camera systems, and cases, more efficient. Their functionality can also play a big part. The ease of interchangeability is key. While the physician holds the camera control body in a steady hand, the 3 mm arthroscopic probe is almost constantly on the move to provide views of different areas of the joint. Sometimes he'll need a wider view of the anatomy, and a switch from a 30-degree to a 70-degree-angle scope will be warranted. When a camera and scope were manufactured as one unit, the entire setup had to be unplugged and replaced at the video tower. Now, the interchangeability of scope components, independently from the camera, without much maintenance, is a huge time- and labor-saver. Scope probes with independently movable light sources can improve visualization efficiency as well.

A scope whose lens is able to remain clear is also a huge advantage. It may not seem like much of a hardship to take a couple of seconds here and there to remove the probe to wipe off a fogged-up lens, but consider this: There are as many as 350 steps in a routine arthroscopic rotator cuff repair. It's hardly efficient technique to add "clean the lens" at irregular intervals between them. Scope lenses that feature anti-fog treatment or technology, or pre-use anti-fog solutions or pre-warming holders prevent such delays.

The video towers to which the scopes and cameras are connected have seen their share of improvements as well. The equipment, which previously consisted of cabinets on wheels full of separate image processing, light source and other components, has now been streamlined into a single unit with a smaller footprint, often mounted on an equipment boom, which makes turning over cases much more efficient. These control units are also able to conveniently interface with the Internet for image archiving and streaming broadcasts, something that it once took the assistance of a team of audiovisual experts to accomplish.

Incidentally, since the arthroscopic shavers we use to debride and suction out damaged tissue are specifically designed to fit a particular manufacturer's handpiece, and since those units are compatible only with each manufacturer's towers, a physician's choice of arthroscopic tools may be in large part driven by his choice of imaging components. For many users, there isn't as much of a distinctive difference between makes of shavers as there is between cameras and video, so the technology is a package purchase.

3. Simplified suture tying
Implantable anchors and high-strength suture are reliable fasteners for securing tissue to bone in the course of a joint repair. The ability of a surgeon to tie a reliable knot in the suture by way of arthroscopy's minimally invasive incisions, however, can prove challenging. Over the past decade, the development of mechanical suture passers and knotless fixation systems have lent confidence to sports medicine practitioners, especially those working in the shoulder.

Passing the suture has historically required manually penetrating the tissue, then (from an access port) manually grasping the suture to pull it through, a 2-step process. The antegrade suture passer reduces that to one step. Working through a single port, you pull the trigger to push the suture through, then you manually grasp it. Another advance further simplifies that one step, passing the suture through the tendon, then mechanically grasping it with its other jaw.

Up until the past few years, the physicians who have trained us in arthroscopic techniques have held firmly to the opinion that there is nothing as effective as tying a knot, and for a long time that was true. The quality and stability of knotless anchor kits and other implantable, pre-tied systems that feature sliding knots that can be tightened to a case's need have improved a great deal, providing a solid, easily reproducible solution even for those who aren't comfortable with arthroscopic tying.

While it's not unheard of for these pre-prepared systems to fail following surgery, manually tied knots can cause post-op complications, too, if they should migrate into the wrong part of the cartilage. In certain areas of the shoulder, knotless anchors can even be more effective, and present less risk, than arthroscopically tied knots.

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