Anterior knee pain (often called “patellofemoral pain”) can become a problem after an injury to the front of the knee or often it can come on more gradually. Patients with pain usually describe an annoying ache that is worsened with prolonged knee flexion, such as during a long car ride. Anterior knee pain is almost always activity related. It is often difficult for patients to walk up and down stairs without aggravating the pain. When it comes on slowly over time it is often related to include activity changes, training errors, weight gain, flexibility deficits, and relative weakness. Such weakness can be relative to the amount of activity that the patient is trying to do or it can come as a result of a general sickness that affects overall strength. Sometimes in children and adolescents rapid growth (height and weight) together with activity produces overload.
Other times, the pain can begin after a blunt injury to the front of the knee that has resulted in damage to the knee possibly including bone bruise, soft tissue injury, and or cartilage injury. The pain from the injury often results in limited activity, which causes stiffness and weakness in the leg and when it stops hurting, patients may have tried to just go back to their prior activities. But if their leg was weak and stiff from the period of pain and limited activity, it would not be able to stand the “normal activity” it did before and overload would result.
What happens is simply that the amount of pressure and/or tension applied to the bones, cartilage, muscles, tendons and ligaments around the knee is more than they can stand. Another way of saying this is that the overload of the muscles, tendons and other soft tissues around the knee occurs when the loads imposed with activity overwhelm the body’s ability to maintain tissue homeostasis (healthy tissue in balance). Our bodies can adapt over time to gradual increases in activity. Activity, even healthy exercise produces some tissue damage that the body heals quickly and rebuilds, often resulting in the ability to do even more. This balance of tissue damage and rebuilding produces a balance that is referred to as homeostasis. This is a beautifully coordinated response to activity that produces a response to any situation or stimulus that happens. When activity decreases, tissue atrophies (shrinks and weakens). Overload occurs when there is more tissue damage than healing. This overload of tissue produces microscopic tissue injury, inflammation, swelling and pain. Those symptoms send a message to your brain (which individuals often ignore initially) telling you to slow down or stop.
It is important for the doctor to be as specific as possible in finding the specific cause of knee pain in order to provide the best chance of recovery. There are many different diagnoses that can contribute to the symptom of anterior knee pain. Some of these diagnoses include patellar tendonitis, quadriceps tendonitis, medial plica syndrome, patellofemoral arthrosis, knee joint effusion, bone bruise and patellofemoral malalignment to name just a few. When a specific diagnosis can be determined, treatment can be more specific. Sometimes the pain is felt in the knee but is really coming from another location (this phenomenon is called “referred pain”). Pain can be referred to the knee from various problems in the hip, thigh or from a pinched nerve in the back. Usually, but not always, such causes of referred pain can be suspected by reviewing symptoms, physical examination and x-rays.
A rehabilitation program can be designed to help treat each of these factors including activity modification, stretching, strengthening, use of a knee sleeve, patellar taping, physical treatment like ice and other modalities, and sometimes prescription or over the counter medications. Over the counter supplements that include glucosamine and chondroitin sulfate are often helpful as well and have less potential side effects than prescription medications but take 4-6 weeks to have an effect. Medications or supplements in the absence of the rest of the treatment plan are unlikely to solve your problem. It is often best to begin recovery under the supervision of a physical therapist experienced in the treatment of patellofemoral problems. During recovery, it is very important to realize that the principle of “no pain, no gain” must be abandoned. If exercises or activities are making your knee hurt, you need to back off and try a different approach which can be suggested by your therapist or doctor. After bringing the pain under control, a gradual plan of increased exercise and activity must be part of the plan.
Sometimes there are pre-existing features of your natural anatomy that predispose you to overload of certain parts of the knee. Such factors can include the alignment of the leg bones and sometimes the presence of flat feet (hyperpronation). Unless tissue damage and arthritis are very advanced, most patients with such situations do respond very well to treatment without surgery.
Fortunately the large majority of patients with anterior knee pain from all these causes can be successfully treated without surgery. It is necessary to be patient as improvement may be very gradual and your recovery may have peaks and valleys. Occasionally, pain is refractory to an earnest effort at non-operative treatment and surgery is needed. At that point the necessary surgery depends on a very specific diagnosis of what is causing the problem. Sometimes plain x-rays combined with the history and physical exam are all that is needed to have an accurate plan, but other times CT scan, MRI scan, bone scan or a combination of these tests are necessary to refine the diagnosis and treatment plan.
When surgery is necessary, the procedure is designed based on the most specific diagnosis possible. Sometimes that involves arthroscopic surgery and sometimes more major surgery is required. But remember, surgery should only be considered as a last resort when patient and complete effort has been given first to non-surgical treatment. Should surgery be considered in any particular patient with anterior knee pain, it must be designed to both confirm the diagnosis and logically cause the origin of the pain to be restored to a more normal situation. The success rate of surgery for anterior knee pain depends upon accurate diagnosis of the cause.