Patellar Tendinopathy and Other Knee Conditions

Today Austin covers a host of knee conditions, including jumper's knee, clergyman's knee, carpenter's knee, and just about any other profession's knee. Listen in to learn about various knee tendinopathies, bursitises, growth plate disorders, and more.

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Transcript

Hello and welcome back to the OCS field guide podcast. Today we’ll be tying up some of the remaining loose ends related to the knee joint. We’ll be talking about a few miscellaneous diagnoses that you should be able to recognize and distinguish from one other, and then taking a deeper look at management of patellar tendinopathy. 

Let’s start with a question:

A female volleyball player presents to an outpatient physical therapy clinic with complaint of pain in the front of her left knee. Her pain began about 6 weeks ago after having started playing for a club volleyball team after her school volleyball season ended. She is still able to play, and her pain improves as the game goes on. Her knee hurts worst when moving after periods of inactivity and the next day after a game or hard practice. Objective exam reveals isolated tenderness to palpation of the superior portion of the patellar tendon and inferior pole of the patella, decreased hip abduction strength, and decreased quadriceps and hamstring flexibility. Which of the following is the most useful additional piece of information for making an accurate diagnosis?

A. Playing volleyball year-round
B. Valgus collapse during single leg squat
C. Familiar pain with decline squat
D. Age

Although A, B, and C are useful pieces of information that we should probably consider with this case, none of them help differentiate what the most likely pathology is in this case. The most likely two diagnoses with this history are patellar tendinopathy, and Sinding-Larsen-Johansson syndrome. Sport specialization is a predictor of both of these diagnoses, as well as patellofemoral pain and Osgood-Schlatter disease. B. Valgus collapse during single leg squat is a common finding with a myriad of knee problems including these diagnoses. Answer C, familiar pain with decline squat again would be true of both patellar tendinopathy and SLJ. But answer D. Age is correct because it gives us the vital information to know if this is a true patellar tendinopathy or if it is an age related growth plate irritation as with Sinding-Larsen-Johansson Syndrome. Now, this is the kind of question the OCS might make into a multi-part question, and if they said the age was anywhere from 10-14 or indicated a recent growth spurt, you’re going to want to pick SLJ as the answer. We’ll dig into that more in the rest of the podcast.

Let’s jump into the hallmarks of some miscellaneous knee diagnoses. Even if the OCS does not test you specifically on one of these diagnoses, they could pop up as other answer choices, so being familiar with them could help you rule out wrong answers.

Let’s start out with a tissue that we don’t often think of being injured: fat. Infrapatellar fat pad irritation (also known as Hoffa’s knee, Hoffa’s pad syndrome, etc.) will present with repetitive extension/hyperextension movements or activities and is thus more common in sports like gymnastics. It can also present secondary to a myriad of other issues such as knee OA, obesity, postoperatively due to trauma from arthroscopic equipment, etc. Pain will be in the front of the knee behind the patellar tendon and may be provoked with forced knee extension or deep palpation in the region of the infrapatellar fat pad, which is basically along the anterior joint line behind the patellar tendon. 

Now on to diagnosis near and dear to my heart, or I should say, near and dear to my right knee: IT band friction syndrome. This is very common in runners and often comes on after an increase in training load or addition of very hilly terrain. It can also happen from any activity with repeated cycling through about 20-40 degrees of knee flexion where the IT band slides over the lateral epicondyle of the knee like walking down hill or driving stick shift in stop-and-go traffic. It’s characterized by pain on the outside of the knee and will often present with tenderness to the lateral epicondyle. One provocative test to confirm is the Noble Compression test where the clinician will put pressure on the lateral epicondyle and then cycle the knee in and out of flexion. A positive test will reproduce the patient’s familiar pain. We don’t have a ton of research on treatment, but what we do have points to addressing a patient's specific impairments including hip and knee motor control or biomechanical issues, lower quarter flexibility and strength, and/or myofascial issues. And if you want my two cents, have your runners and walkers avoid steep downhills. 

Now for a few “bursitis” diagnoses. Remember, a lot of things get called “bursitis” in the medical community that really have a more complex cause. So for the OCS, remember that a true “bursitis” should come along with clear signs of “-itis”. In other words, look for things like warmth and edema. Pes anserine bursitis obviously presents at the pes anserine where the tendons of the sartorius, gracilis, and semitendinosis tendons attach. It can come along with a number of different histories including repetitive motions or sporting activities, and is very common in individuals with osteoarthritis of the knee. There are three main peripatellar bursitises that you might need to recognize. Suprapatellar bursitis will present about like it sounds, with swelling and tenderness in the suprapatellar bursa. This will have a similar region of pain as quadriceps tendinopathy, but you can expect it to have some swelling and boginess while quad tendinopathy should not. Prepatellar bursitis (also known as housemaid’s or carpenter’s knee) will present with that swelling and irritation right on the patella between the bone and the skin. This is most often brought on by repetitive kneeling or a blow to the knee cap itself. Infrapatellar bursitis (aka clergyman’s knee) presents more distal close to the distal attachment of the patellar tendon and is also typically associated with kneeling, but more likely the kind of kneeling where you are sitting back on your heels more with more pressure at the tibial tubercle like a traditional prayer posture (hence the “clergyman’s knee”)  rather than being on hands and knees such as when cleaning or installing flooring. Also think about age with pain and inflammation around the distal attachment of the patellar tendon. If you see it in a 12 year old boy for instance, you’re more likely looking at Osgood-Schlatter disease than infrapatellar bursitis.

This brings us to age-specific knee issues that are especially important to consider in light of our discussion of patellar tendinopthy today. There are two age-related growth plate syndromes that can look a lot like patellar tendinopathy: Osgood-Schlatter’s and Sinding-Larsen-Johansson syndrome. Osgood-Schlatter disease is a traction apophysitis of the growth plate at the tibial tubercle and will only occur during growth years mostly in adolescents participating in sports that involve repetitive jumping and/or squatting. It is found in females aged 8 to 13 years and males aged 10 to 15 years. When it has been going on a while it will often present with a prominent tibial tubercle due to calcification around the insertion of the patellar tendon. Sinding-Larsen-Johansson syndrome, which we touched on in our question, is a similar traction apophysitis, but occurs at the patellar growth plate and it is a little less common than OSD. It will present with pain at the inferior pole of patella similar to patellar tendinopathy, but is due to irritation of the growth plate located at the inferior aspect of the patella rather than the patellar tendon attachment. Again, this will only happen with open active growth plates, so it is typically only found during the same growth years. As is true with so many musculoskeletal issues in adolescents, both of these conditions are much more frequent in individuals who specialize in one sport early on. Both can have a “warm up phenomenon” where pain is worse after a period of inactivity, but improve as activity continues. Both are technically considered self limiting, as they will improve with skeletal maturity, but that doesn’t necessarily mean they should just play through it anyway or that we can’t help them. Also, extra cation may be warranted with SLJ as it can develop into an actual avulsion of the inferior pole of the patella. We don’t have much research to support one specific management protocol with either of these diagnoses, so I would maily expect the OCS to examine your ability to recognize these diagnoses rather than select optimal treatment. More than likely though, especially with an acute case of OSD or SLJ you would be more cautious on loading the extensor mechanism early on, and focus more on rest and offloading and/or load management early on rather than jumping right into a pain provoking patellar tendon loading program. And although we don’t know the perfect treatment protocol, if the OCS were to ask, research points to treatment consisting of education of the child and family on load management and avoiding early sport specialization, as well as addressing any strength, flexibility, and motor control or biomechanical impairments. 

Let’s also talk about lateral patellar instability. The diagnosis of patellar instability will, obviously, come with a history of an instance of patellar subluxation or dislocation, where we define a subluxation as lateral displacement and quick relocation of the patella without a relocation maneuver required, where a true dislocation is one that must be reduced by a specific movement or by a medical professional. Most patellar dislocations are reduced just by straightening the knee, so many true dislocations don’t actually have to be put back in place. Patellar subluxation or dislocation is most common in ages 10-17 and in females. One clinical test to be familiar with for this population is the patellar apprehension test, where the patella is pushed laterally and the patient is observed for signs of discomfort, apprehension, or quad contraction to keep the patella located. Remember also that “normal” patellar glide should be between 25-50% of the width of the patella, and greater than this is going to tell you about either MPFL laxity or trochlear dysplasia. The vast majority of research on patellar instability is done on first-time true dislocations, so keep that in mind. Approximately 36% of first time patellar dislocations will have a subsequent dislocation, though certain subgroups are at a higher risk. The strongest predictors of recurrent patellar instability after initial dislocation are: trochlear dysplasia, skeletal immaturity, age below 18 at first dislocation, female sex, patella alta, greater distance between tibial tubercle and trochlear groove, and history of contralateral dislocation. Overall, about 60-70% of first-time dislocators will be successful at preventing future dislocation with non-surgical management. However, individuals with both skeletal immaturity and trochlear dysplasia have a 68% rate of recurrence. The most common surgical options to address patellar instability include distal realignment osteotomies such as the fulkerson osteotomy, trochleoplasty, MPFL reconstruction, lateral retinaculum release or some combination of those depending on the patient’s anatomy. A 2015 Cochrane review comparing surgical repair versus non operative management for first-time dislocations found only low-quality evidence for significant reduction in re-dislocation rate and possible improvement in function in favor of surgery for first time dislocation. However, a 2018 study in the American Journal of Sports medicine found MPFL reconstruction did decrease dislocation rate, but did not improve subjective or objective function compared to bracing and physical therapy. Overall, it's safe to say that even with a complete, traumatic dislocation bracing during the acute phase and physical therapy should be first line management in absence of other problems such as a loose body or other severe osteochondral injury, though more consideration should be given to surgery for those that have multiple risk factors for recurrent subluxation. 

Finally, let’s talk patellar tendinopathy, or “jumper’s knee”. The diagnosis of patellar tendinopathy can be made clinically with pain localized to the inferior pole of the patella and/or the length of the patellar tendon that is consistently provoked with movements that activate the extensor mechanism and put significant load on the patellar tendon. It is especially common in younger athletes that play sports involving a lot of explosive jumping and running such as volleyball, high and long jump, soccer, sprinting, etc. Patellar tendinopathy is more common in males than females. It should pretty much only hurt right at the site, and only during activity. It is worst when beginning activity after a period of inactivity, and typically will have a warm-up effect and improve as activity continues, similar to patellofemoral pain. The big differentiators between patellar tendinopathy are: location (ie, distal pole of the patella and in the tendon vs retropatellar), whether or not they get any pain at rest (patellar tendinopathy should NOT, while you may get movie-goers sign with patellofemoral pain), and gender, where we note that patellar tendinopathy is biased toward males while patellofemoral pain is a lot more common females. Obviously, you need to rule out all the other diagnoses we’ve talked about, and remember that patellar tendinopathy should pretty much just hurt at the patellar tendon. Imaging is not typically necessary, but ultrasound and MRI will usually show signs of degeneration of parts of the tendon, tendinosis, neovascularization, and other changes but the same abnormalities are often found in asymptomatic tendons. Thus the adage is used “treat the donut, not the hole” as there is typically plenty of good tendon to perform all the tasks we require of it. So treatment is focused on improving the loading tolerance of the healthy tendon, rather than “fixing” the degenerative tendon. More on that in a moment. 50% of athletes that have patellar tendinopathy will have recurrent symptoms, and 50% of athletes with patellar tendinopathy will retire from their sport due to this issue, so it’s really important that we know how to treat this well. And for you studying for the OCS, it’s important you know about how to treat tendinopathy, as our most popular journals have put out A TON of literature on tendinopathy and patellar tendinopathy specifically in the last 5-10 years. 

That being said, let’s move on to treatment. As I said, our knowledge has grown a lot in this area recently, so if you’ve been out of the literature for a while, this is definitely an area to spend some time on. The times of ultrasound, only doing eccentrics and stretching, and avoiding pain should be long past now. Here are four main categories of what you need to know to incorporate into treatment: 1. Analgesic techniques; 2. Pain monitoring; 3 Progressive tendon loading; and 4. The rest

1. First let’s talk pain relief. We have the power to relieve pain even during a lot of activity or during a sport season with isometrics and taping or strapping. Isometric patellar tendon loading has been shown to induce analgesia and decrease quad inhibition. Studies such as Rio et al in 2015 used a protocol of 5x45” holds in mid range (think spanish squad, partial inclined squat, or mid range on a knee extension machine). Other studies have supported this protocol as well and shown this to be a good practice for use in season with athletes prior to games or practice to decrease pain during play. Although both isotonic and isometric exercises IN-SEASON are similar in decreasing overall pain, isometrics induce significantly greater short term analgesia, which allows for greater loading with an isotonic program following or greater participation in sport. The question follows then, do we need to have these athletes stop their sport in season to rehab this injury? Overall evidence supports that there is not significant danger to allowing continued sport participation with implementation of a loading program. In addition to isometrics, patellar tendon sports taping and patellar tendon strapping are both effective at reducing or eliminating pain during activity participation. 
2. Second, though we can relieve pain, pain is allowable and even encouraged within a certain range with patellar tendon rehabilitation. How much, how often, and with what load we perform exercises should be pain based. Here are the rules: Pain is allowed to reach but not exceed 5/10 during, immediately after, or the morning after an activity. In the course of rehab, overall level of pain and/or stiffness should not increase from week to week. This principle was first put forth by Silbernagel et al in 2007 with regard to achilles tendinopathy, but has been born out in multiple studies with patellar tendinopathy as well. 
3. Third, progressive patellar tendon loading should be the mainstay of patellar tendinopathy rehab. We got this partially with the whole “eccentrics” craze. And eccentrics do work, but only because they allow us to load a little heavier and we make people do them really slowly. However, we now know the best rehab program is going to be a progressive tendon loading program that begins with isometrics and progresses through stages of slow heavy loading, to even heavier loading, and finally on to plyometric and sport specific loading are superior to only eccentric loading. In their recently published 2021 study in BJSM Breda et al used a progressive tendon loading program which had superior outcomes in pain, function, and return to sport to a more classic eccentric decline squat program. They used a four stage approach where each stage had to last at least one week, and criteria for progression to the next stage was having 3/10 or less pain with all activities in that stage. In the first stage they utilized daily 5x45” isometric contractions with increasing weight as tolerated. Then in stage two they maintained isometrics on every first day and implemented heavy slow isotonic loading every second day beginning with 4 sets of 15 and progressing slowly to 4 sets of 6 with heavier load. Then in stage three, on every third day they added plyometric and other high tendon load energy storage and release exercises such as jump squats, box jumps, and cutting maneuvers, all while still performing isometrics on every first day, and isotonics on every second day. Finally in stage four they were progressed to sport specific activities and exercises every 2-3 days while still performing the isometric loading on days that they were not performing sport specific activities. Return to competition was advised after they were able to perform all stage 4 activities with 3/10 or less pain. Obviously, don’t go memorize this protocol for the OCS, but I detailed it because it summarizes a lot of the concepts from research in recent years and because it’s a pretty good new study that demonstrated greater improvement with thoughtful progression of loading than with a heavy loading or eccentric only program. It also highlights the need to incorporate plyometric, sport specific activities, jumping and landing mechanics, etc rather than leaving these individuals when they are able to do ADLs and exercises without pain. 
4. What we’ve talked about thus far should encompass the vast majority of what you do with these patients and should be the “non-negotiables”. Beyond that, any other patient specific impairments can be addressed such as hip strength, flexibility, biomechanics, motor control, etc. There is weaker evidence for things like extracorporeal shock-wave therapy, low level laser, PRP injections and even peritendinous corticosteroid injections, but it's important to note that all of the studies where these treatments had significant effect included some level of patellar tendon loading.

That was probably more detail than you will need for the OCS, but remember that isometrics and taping or strapping are analgesic and can allow for decreased or pain free exercise and sport participation. A pain-based progressive patellar tendon loading should dominate what we do with these patients, and we can load them up to, but not exceeding 5/10 pain during, after, or the next day after activity or exercise. Your loading program should progress all the way to plyometric, sport specific activity, taking into account jumping and landing mechanics, and the individual demands of the sport in question. And of course, treat whatever else you find. Oh, and by the way ultrasound whether pulsed or continuous or whatever has been proven to do nothing for patellar tendinopathy.

The only thing we haven’t talked about yet is the other side of “jumper’s knee”: Quadriceps tendinopathy. Quad tendinopathy is very similar to patellar tendinopathy in that the quad tendon and patellar tendon are both part of the terminal aspect of the extensor mechanism. It’s much less common than patellar tendinopathy and you can, obviously, expect quadriceps tendinopathy to present above the patella. Quad tendinopathy will have pain provoked more specifically with deeper loaded knee flexion, as that is mechanically where more load will be placed preferentially on the quad tendon rather than the patellar tendon. Overall we don’t know a ton about how to treat these differently than patellar tendinopathy, but there was a good clinical commentary in JOSPT in 2019 by Sprague, Epsley, and Silbernagel on distinguishing patellar and quadriceps tendinopathy. They suggest using all the same principles that we have already discussed with patellar tendon loading, but adjusting the program to be cautious with loading deep in knee flexion during acute stage, but to be certain to progress to loading progressively deeper ranges of knee flexion and to do so with varied degrees of hip extension ROM in order to bias different aspects of the quad tendon due to differing levels of rectus femoris involvement. For example, including both a reverse nordic exercise, and a deep squat or leg press. 

That wraps up this episode of OCS field guide. If you haven’t already, tell your friends and colleagues that are studying for the OCS about our podcast. And if you are interested in using medbridge, or already are a user, but sure to use our code “FIELDGUIDE” to get the maximum discount when you sign up or renew.