Pediatric Knee Arthroscopy: The Basics of Pediatric Knee Arthroscopy from a Collection of Pediatric Sports Medicine Experts

Abstract

Background/Objective:

To share technical pearls of a basic knee arthroscopy in a pediatric patient by presenting tips and tricks used by experienced pediatric arthroscopists.

Indications:

Knee arthroscopy is a common procedure performed by most orthopedic surgeons. However, technical considerations and equipment should be considered before performing this procedure in a pediatric patient. This video provides information on indications, equipment, and patient positioning, as well as outlining a systematic approach to diagnostic arthroscopy and pertinent pediatric anatomy.

Discussion/Conclusion:

This video provides an excellent overview as well as specific pathology-dependent considerations for the inexperienced orthopedic surgeon, or the orthopedic surgeon who rarely performs knee arthroscopy.

Patient Consent Disclosure Statement:

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

The objective of this technique video is to describe technical pearls of a basic knee arthroscopy in a pediatric patient by presenting a collection of tips and tricks from experienced pediatric arthroscopists.

The authors and contributors of this video did not receive funds directly related to this educational content. Equipment and supplies were provided for by Stryker and Allosource.

Knee arthroscopy is a common procedure performed routinely for most orthopedic surgeons. However, technical consideration should be considered when performing a knee arthroscopy in a pediatric patient, primarily due to smaller anatomy. The primary urgent indication for a young pediatric knee to undergo arthroscopy is for a septic knee. ¹ Other indications may include synovectomy, such as in a target joint of a hemophiliac, synovial biopsy, treatment of patellofemoral instability, anterior cruciate ligament (ACL) tear, discoid meniscus or other symptomatic meniscus tear, reduction and fixation of a tibial imminence fracture, removal of an intra-articular foreign body or loose body, or treatment of osteochondritis dissecans or other osteochondral abnormalities. ² One important consideration is equipment, particularly if special equipment is needed for a pediatric knee.

Here is Matt Millewski from Boston Children’s Hospital with tips on appropriate equipment selection.

I was taught to consider switching to a smaller 2.7-mm scope when kids are <8 years of age; however, I find that the 3.5-mm scope can be used all the way down to about age 4 years. We have shorter, typical 2.7-mm arthroscopes, but we also have a longer 2.7-mm arthroscope that I use routinely for elbow arthroscopy and is occasionally useful in these smaller knees. I use the pump for knee arthroscopy, but some will use just gravity. For standard knee arthroscopy, I generally use a pump pressure between 30 and 35 mmHg. Regarding arthroscopic instruments, most of the regular instruments are appropriate for pediatric and adolescent patients. In general, small-joint arthroscopic instruments for ankle, elbow, and wrist arthroscopy are good to have for all cases as backup if specific knees are tighter or stiffer than others. I use a standard 3.5-mm shaver for most arthroscopic knee cases.

Here is a list of suggested equipment for a pediatric knee arthroscopy. Generally, in a pediatric knee, a leg holder is not needed. However, we do recommend positioning the child on the end of the bed to allow the leg to either drop over the side of the bed or to flex the knee onto the bed during arthroscopy. For the inexperienced arthroscopist, but particularly important in smaller knees, it is advised to insufflate the joint prior to establishing the anterior lateral portal. An 18-gauge needle can be used, and approximately 60 to 100 cc of normal saline is injected into the joint until there is a tense palpable effusion.

Here is Dr. Todd Milbrandt from Mayo Clinic in Rochester, Minnesota, regarding his tips for appropriate camera insertion.

My landmark is inferior pole of the patella and just lateral to the patella tendon itself in the soft spot where I can kind of feel it a little bit more gushy. And if you aimed your knife toward the notch, for the most part, you are going to be safe.

Here is Marc Tompkins from TRIA Orthopedic Center in Bloomington, Minnesota, with his tips on transillumination for medial portal establishment.

I pull my scope back, kind of look down into the left, like you can see here. What that does is, number one, it gives you a big area to hit with your spinal needle and then you can also do transillumination on the skin, and you can see if there are any blood vessels. I also like to have the knee bent at 90° to let everything in the anterior aspect go under the most stress possible.

For those individuals who are new to arthroscopy or for the surgeon who does not do a large volume of arthroscopic cases, here is Dr. Ted Ganley from the Children’s Hospital of Philadelphia with some general guidelines that may set you up for more success.

I would like to think of arthroscopy is as if you are flying a plane, so you want to keep a level horizon. And so then it is as if the plane does not look forward, but there is a 30° periscope which looks to the left or to the right. Number two, people, when they are learning arthroscopy, tend to go too close. And then there is a second error, which is to go, when you are sitting back, is to sit in the fat pad. The reason you should not do that is with these high-flow cannulas, the fluid comes not from the very tip, but comes from a few millimeters back. So this is actually closing the curtains, so the fat pad gets bigger if you sit there. So you like to pop through. The third thing is, if you are looking toward a meniscus, to be continually bringing your camera hand toward the ipsilateral or contralateral shoulder and that keeps you away from the femoral condyle.

The following areas should be visualized during any diagnostic knee arthroscopy.

Adequate visualization is imperative to the safety of the surrounding structures and success of the procedure.

Here is Dr. Eric Edmonds from Rady Children’s in San Diego, California to tell us more.

My first step, especially in these smaller knees where there is not a lot of space, is definitely getting rid of the ligamentum mucosum or part of the Hoffa fat pads. Obviously you do not want to get rid of all the Hoffa fat pad, but I think that helps with a couple of different things. One, for visualization, but also for getting your instruments back in and out of the joint, particularly on the little knees.

For many surgeons, diagnostic or therapeutic arthroscopy begins in the suprapatellar pouch.

Here is Dr. Jennifer Beck from UCLA Medical Center in Los Angeles regarding her tips for access of the suprapatellar pouch.

When I am up in the suprapatellar pouch, my goal is to look at the inferior surface of the patella and identify that as my landmark, which is, you can see there in the top part of our screen. Suprapatellar pouch can be a place that infection likes to hide and can be very loculated. So in this situation, making a superior lateral portal can be very helpful. And then when you come in laterally, you want to come just distal to the vastus lateralis, hopefully within the tendonous portion and the retinaculum. You have direct visualization there, and you can use this as your portal in identifying any loculations that you may need to breed.

The patellofemoral joint and gutters of the knee should be inspected for pathology.

Here is Dr. Matt Schmitz from Brook Army Medical Center in San Antonio, Texas, regarding his tips for the evaluation of the patellofemoral joint.

And then I like to start over along the lateral side, we will go into the lateral gutter. So as you go in, you want to bring your eyes down. So here, we are looking back to the left. You can see the popliteal is coming in back behind the lateral meniscus. So, we can make sure that there is no loose bodies in the posterior lateral gutter, and then we will ride back up. Usually at this point, we can see a good view of our lateral patella facet, which is right there. Coming across, we can look back and see how the patella rides within the trochlea, make sure there is no engaging defects or patellar tilt. And we will do the same thing where we will come down the medial side. Here, you will see a remnant of a medial plica that is present there. You can sometimes see some reciprocal changes on this medial portion of the femoral condyle if it is irritating.

Owing to the size of many pediatric knees, some special considerations may apply to decrease iatrogenic damage to the medial femoral condyle.

Here is Dr. Lee Pace from Children’s Medical Center in Dallas, Texas regarding his management of a tight medial compartment.

If you are going after a medial meniscus in a young kid, be very prepared and very comfortable with an medial collateral ligament (MCL) fenestration approximately. So, come up here with a spinal needle, into the femoral insertion of the MCL, and you can just go percutaneous with valgus and relative extension and just poke, poke, poke, poke, poke, poke, poke that MCL until you get that visualization that you need, and that medial compartment gap will open.

Here is Dr. Kevin Shea with Lucile Packard Children’s Hospital at Stanford and Palo Alto, California, with more information on anatomic considerations in pediatric knees.

For meniscus repairs, the neurovascular structures need to be very carefully considered with any suture placement. The use of all inside devices carries some unique risks, especially for posterior meniscus repairs. On the medial side, the neurovascular structures may be within 13 to 20 mm of the posterior edge of the meniscus. On the lateral side, this distance is even less, at five 10 mm in younger patients. ³ All inside devices may go through the joint capsule and should be placed with caution, especially in these regions closer to the posterior regions of the meniscus.

Especially in the setting of a septic knee or when the surgeon needs to better evaluate the posterior aspect of the intra-articular space, the following tips may help.

Here is Dr. Yi-Meng Yen from Boston Children’s Hospital regarding his tips for accessing the posterior aspect of the knee joint.

You can kind of move the posterior cruciate ligament (PCL), push it out of the way, and I am going toward this crevice into the back. I get right under the meniscus and it pops you right into the posterior medial aspect of the knee. So I am looking now at the posterior medial aspect of the knee. This is the posterior horn of the meniscus, and then what I will do is then I will go posterior lateral. And when I do that, I will switch portals. So I will come in from the anteromedial portal. You are looking at the ACL there, it is a little bit flat, and I want to go into this posterior lateral aspect of the knee. I am going to follow that corner. So now I am in the posterior lateral aspect of the knee, and you can see the posterior horn of the lateral meniscus right there, and you really have to get into the back of the knee to thoroughly lavage it.

Thank you for watching this video.

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