This is just to start us off with a wonderful picture of a really good quadriceps muscle. One that, unless we are in sports medicine, we may not often see but clearly discernible here on the medial side of the knee is the VMO and on the lateral side the vastus lateralis. When knee pain is felt to have a component of patellofemoral pain it is also important to understand that there are conditions which actually affect the compression of the patella against the femur. Increased knee flexion and increased quadriceps tension can independently increase this compressive force. Alignment of the patella on the femur and the congruence of the patella in the trochlear groove also are part of the total picture of compression and pain. For example, when we walk, compressive forces are about 3/10ths our body weight, but this increases to seven times body weight when we squat and have excessive knee flexion.
In summary, when we look at the knee, we need to keep in mind that the knee connects two long lever arms and is affected by local, proximal and distal events. It depends on soft tissue, not bony configurations, for stability and also for the mobility that we need. It is full of complex joints and relationships. There are actually 14 muscles that control the knee; six act only at the knee but seven also act at the hip and this is often forgotten, but won’t be today. And one also at the ankle. So thinking about the knee and the kinetic chain as a closed kinetic chain, which we see here, where there is at least partial weight-bearing and the feet are in contact with a weight-bearing surface. Whether it’s a closed kinetic chain or an open kinetic chain, which we see here, and although many people discuss what is an open kinetic chain, I think when you can see the soles of their feet it’s pretty much assured that you are talking about an open kinetic chain. But whatever the case, open or closed kinetic chain, what we need to remember is that we must consider the knee in terms not only of what it does and where it is, but also as a response to forces and conditions in its environment. I’ll now turn the podium back over to Bob and we will begin our vignettes, interestingly enough, with a sports-related case.
Our first patient is a case of knee pain in a 35-year-old female jogger. She has complained of anteromedial knee pain, worse on the right. Present over the past couple of weeks of gradual onset. Improved with rest additionally, and now constant. Worsened by running, especially by longer runs. Thighs and shin pain on non-running days. Her goals are the discover the source of the pain, fix it and get on with her training. This occurs in the background of the fact that she is just beginning to train for a marathon and she has recently increased her mileage from four to five miles three days a week, to five to 12 miles five times a week. She has run a marathon before, some ten years ago and two children ago. She ran in college as a middle distance runner and some sort of knee problem then that was eventually arthroscoped, and she recovered from that sufficient to undertake day-to-day activities. Her physical exam, as she came in, was examined by the house officer. She showed medial peripatellar tenderness and patellofemoral crepitus. Was tender to deep palpation of the quads, hamstrings, anterior calf at rest and with contraction. Upon further review it was noted that she also had normal patellar tracking. when she extended her leg the patella stayed right in the midline. There was a tender medial synovial plica, just medial to the patella. There was no tibial femoral crepitus, no crepitus rising from the weight-bearing compartment. She had no focal tenderness over the tibial tuberosity where the patellar tendon inserted.
The first thing is that when we are weight-bearing
Our thought was that she had anterior knee pain
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