Ep. 5: Extensor Mechanisms
Ep. 5: Extensor Mechanisms
Part 1: Hey everyone, I’m Dr. Jay Bowen. I’m a board-certified physiatrist here at New Jersey Regenerative Institute, or NJRI. For the past few weeks I’ve been making videos on the knee. It’s the main thing I treat here at NJRI and I’m on a journey to educate the public on knee anatomy and injuries. That way, you can start to understand what’s causing your pain, and seek the correct medical help. Here at NJRI, we release your intrinsic ability to heal.
Part 1: Hey everyone, I’m Dr. Jay Bowen. I’m a board-certified physiatrist here at New Jersey Regenerative Institute, or NJRI. For the past few weeks I’ve been making videos on the knee. It’s the main thing I treat here at NJRI and I’m on a journey to educate the public on knee anatomy and injuries. That way, you can start to understand what’s causing your pain, and seek the correct medical help. Here at NJRI, we release your intrinsic ability to heal.
Click through our channel to see our previous episodes on the knee series! Today I’m going through the extensor mechanism of the knee. Feel free to leave a comment below telling us what you’d like to hear more about in future videos. If you like what we’ve been putting out on Youtube, throw us a like and subscribe to our channel. It costs you nothing and it really helps us out! Okay, now let’s get into it!
Part 2: What is the extensor mechanism? / Anatomy Overview
The extensor mechanism refers to the complex anatomy responsible for extending the knee joint. It involves several structures working together to allow for the straightening of the knee and to support weight-bearing activities. The mechanism consists of the quadriceps muscle group, quadriceps tendon, patella, patellar retinaculum, patellar ligament or tendon and most know it, pes anserine, and adjacent soft tissues. Injuries to the extensor mechanism are common and consist of chronic degenerative injuries, overuse injuries, and acute trauma.
The extensor mechanism of the knee begins above at the hip. Now, let’s do a quick overview of all of the different things involved in the extensor mechanism.
Part 3: First, the quadriceps muscle group.
This is a group of 4 muscles located on the front of the thigh. The quadricep muscles include the rectus femoris and the vastus lateralis (on the outside), medialis (on the inside), and intermedius. Then, there is the quadriceps tendon. This tendon connects all the quadriceps muscles to the patella or kneecap. It is a thick, strong tendon essential for transmitting the force generated by the quadriceps muscles to the patella.
The patella is a small, triangular-round bone in the front of the knee joint. It acts as a fulcrum, increasing the leverage of the quadriceps muscles for increased power and protecting the front of the knee joint. There is also the patellar tendon below the kneecap. This tendon extends from the inferior pole of the patella to the tibial tuberosity on the front of the tibia or the top of the shinbone. It continues the transmission of force from the quadriceps muscles, via the patella, to the tibia. The quadriceps mechanism term encompasses the quadriceps muscle group, quadriceps tendon, patella, and patellar tendon, all of which work together to extend the knee joint.
This is a group of 4 muscles located on the front of the thigh. The quadricep muscles include the rectus femoris and the vastus lateralis (on the outside), medialis (on the inside), and intermedius. Then, there is the quadriceps tendon. This tendon connects all the quadriceps muscles to the patella or kneecap. It is a thick, strong tendon essential for transmitting the force generated by the quadriceps muscles to the patella.
The patella is a small, triangular-round bone in the front of the knee joint. It acts as a fulcrum, increasing the leverage of the quadriceps muscles for increased power and protecting the front of the knee joint. There is also the patellar tendon below the kneecap. This tendon extends from the inferior pole of the patella to the tibial tuberosity on the front of the tibia or the top of the shinbone. It continues the transmission of force from the quadriceps muscles, via the patella, to the tibia. The quadriceps mechanism term encompasses the quadriceps muscle group, quadriceps tendon, patella, and patellar tendon, all of which work together to extend the knee joint.
Finally, there is the tibial tuberosity, various ligaments, retinacula, and additional muscle tendons from that insert into the tibia called the pes anserine. The tibial tuberosity is essential for knee extension and the ligaments and retinacula are very important for stabilizing the patella and maintaining its position known as tracking during knee movement.
Part 4: Okay, now that I’ve given you a 101 on the anatomy of the extensor mechanism let’s get into some diagnoses I commonly give for extensor mechanism injuries. If any of these sound like something you’re struggling with, please give our office a call and schedule a visit so that I can evaluate you and get you on a treatment plan for better function.
Part 5: Oftentimes when athletes come into my office they are struggling with injuries to their extensor mechanisms. One of the most common injuries is patellar tendonitis more accurately tendinosis or Jumper’s Knee. Essentially, this is an overuse injury characterized by inflammation, microtears, and degeneration of the patellar tendon, which connects the patella to the tibial tuberosity.
Repetitive jumping, running, or activities that involve frequent bending and straightening of the knee can strain the patellar tendon and result in a diagnosis of jumper’s knee. If you’re struggling with this you’re likely pretty active and experiencing pain just below the kneecap, especially during activities that load the tendon, such as jumping or squatting. Pain may worsen with continued activity and may also be present during rest in severe cases.
Jumper’s knee is really hard to treat, especially because many of the patients I see want to return to their activity or sport as quickly as possible. Regenerative medicine techniques like I offer here at NJRI provide promising alternatives to traditional treatments. The treatment for patellar tendinosis will depend on severity, which can be evaluated in the office with ultrasound, which is more sensitive than MRI.
PRP or platelet rich plasma can be used for degeneration of the tendon. Although it does respond to PRP, the patellar tendon is more resistant compared with other tendons in the body. For this reason, if the tearing or degeneration is more severe I would consider fat as a source for treatment.
MFAT can fill the gap in the tendon and I have seen better responses with less potential need for a repeat treatment. The largest gaps I see are in patients who have continued knee pain in the front after they had part of the tendon used to repair an ACL tear.. Stay tuned for a video in the next few weeks explaining this procedure more in depth. I also offer shockwave, prolotherapy, percutaneous tenotomy, or combination treatments.
Part 6: Runner’s knee is another common injury I see in my athletes. The more scientific term for this is patellofemoral pain syndrome. This is a condition characterized by pain around or behind the patella, often aggravated by activities such as running, jumping, or prolonged sitting. My athletes often present with dull, aching pain around or behind the kneecap during or after activities, particularly with prolonged bending of the knee while sitting (movie theater sign). Overuse, poor biomechanics, muscular imbalances, and structural issues may contribute to this problem. These injuries can vary in severity and may require different treatment approaches, ranging from conservative measures such as classic RICE protocol - that is rest, ice, compression, and elevation or better yet the MEAT protocol - movement, exercise, analgesia, and treatment all the way to surgery in the most aggressive cases. Typically, I first send patients with this diagnosis to physical therapy or for a functional movement screen because this is most often a biomechanical issue. If you’re worried about developing jumper’s or runner’s knee, a proper warm-up, stretching, conditioning, and biomechanical assessments can help athletes reduce the risk of.
Part 7:Besides these two athletic injuries I also treat a lot of traumatic patella injuries. These include quadriceps tendon and patellar tendon ruptures, patellar dislocation / subluxation, and patellar fracture. The two types of tendon ruptures come from sudden, forceful contractions of the quadricep muscles or direct blows to the knee. Patella dislocation or subluxation is often due to twisting or sudden changes in direction. The fracture usually occurs with a hard fall or collision. All of these injuries require a physical examination, functional tests and imaging for a proper diagnosis. Visit us at NJRI in Parsippany, New Jersey to get evaluated if you had a traumatic knee injury. Unfortunately if the injury is severe, one usually needs surgery, but partial tears or associated injuries can be treated without surgery. You can also call my office to schedule a virtual visit if that’s more convenient for you. If you’re struggling with any of the problems we addressed in this video it’s important to see a professional as soon as possible. Early treatment is one of the largest contributors to positive outcomes. Whoever you are, and whatever you’re dealing with, all of us at NJRI are wishing you a full recovery and years of good health!
Part 8: That’s all for me today! Thanks for tuning in and be sure to give this video a like if you enjoyed it. Also, subscribe to our channel so you don’t miss any future videos! We post new videos every Tuesday, and next week I’ll be doing a video on ACL / MCL injuries. If you like NJRI, give us a follow on our socials: X, Instagram, and Facebook @NJRegenerative. [28] Thanks for your support and have a great week!