Update on Jumper’s (Downhill Runner’s) Knee
It’s been more than two decades since I explored what was known then about the condition “patellar tendinopathy” – aka “Jumper’s Knee.” As I reported then (Therapy Corner #17), this is a condition most commonly found in athletes who engage in repetitive jumping, such as basketball and volleyball, but can definitely affect runners as well. In those individuals, the primary cause is likely the result of running down steep and/or long hills, as this puts the most stress on that structure. (The patellar tendon connects the lower part of the kneecap to the upper shin and is part of what is known as the extensor mechanism of the knee, which includes the quadriceps muscles and tendon.)
When I first wrote about this injury, there wasn’t very much understood as to the causes other than the usual explanation of “overuse” of the tendon. Problem is, just blaming that factor doesn’t account for cases where only one side is affected, since you run the same distance on the other, non-symptomatic side. Clearly, it seemed plausible that a unilateral biomechanical abnormality could be found to explain why this particular structure might be injured. Back then, though, there was a paucity of research along these lines.
As I’ve shown on numerous occasions in the past, there is a great deal of evidence linking abnormal movement patterns of the hips and foot/ankle to the most common of running injuries, “Runner’s Knee,” which affects the back of the kneecap itself. Specifically, those athletes with relative weakness of the hip external rotator and abductor muscles and/or who demonstrate increased pronation movement of the foot during gait are clearly at greater risk for incurring this particular injury.
Because those impairments cause faulty movements in the rotational and frontal (side-to-side) planes of movement of the lower extremity, no one suspected they would be a factor in the development of patellar tendinopathy, since that structure seemed to be moving primarily, if not exclusively, in the sagittal (front-to-back) plane. A recent study in the Journal of Orthopedic and Sports Physical Therapy (Sept. 2018), however, took a new look at this assumption and the results are enlightening.
The study evaluated 192 athletes who participate in basketball and volleyball, quantifying their hip range of motion and strength, ankle range, iliotibial band flexibility, and lower leg/forefoot alignment. Of these individuals, 59 presented with patellar tendinopathy, while the remaining 133 did not. The investigators only knew that some of the athletes were injured and some not; their job was to predict which group an athlete fell into, based solely upon the findings of their examination.
Basically, their hypothesis was that the athletes with much the same characteristics as ones who develop Runner’s Knee – weak hip external rotators and abductors, restricted ankle movement, etc. – would be more likely to complain of patellar tendinopathy, especially if the six parameters analyzed are combined in a rather complicated statistical model. In other words, certain impairments of the hip and ankle/foot are predictive of whether or not an individual is likely to exhibit signs and symptoms of this condition.
The results of their predictions were impressive: they correctly identified with almost 75% accuracy which athletes fell into which group. Of course, there is always a question regarding the applicability of conclusions about athletes that participate in one specific activity (basketball/volleyball) to those who engage in another activity (distance running), but my experience gives me a high degree of confidence that in this case the connection holds.
I’ve previously [Therapy Corner #113] covered the type of exercises that have proven most effective in directly addressing a tendinosis/tendinopathy condition. This new information, however, provides some insight into others that can be employed to both prevent and treat such this particular condition. These exercises can be found in articles 89, 95, and 103 and I highly recommend you make them part of your warm-up routine, even if you have no problems presently.