Musculoskeletal complaints account for about 20-30 percent of all primary care office visits. Having pain or dysfunction in the front part of the knee is a very common presentation in the sports medicine office, and a common reason for a patient to see their healthcare provider with a knee issue.
There are a number of pathophysiological etiologies to anterior knee pain. This blog post will describe some of the common as well as some of the less common causes. It should be said first, however, that a good history and thorough physical exam are essential to an accurate diagnosis of the cause of the anterior knee symptoms. In turn, an accurate diagnosis is essential to optimal management and the best possible outcome.
Two of the most common causes of anterior knee pain in the active person, and what we see in the sports medicine office, are Patellofemoral Syndrome (or what I like to refer to as Patella Tracking Dysfunction) and articular cartilage conditions such as chondromalacia or osteoarthritis (from injury, damage, or wear and tear) involving the patellofemoral compartment.
Patellofemoral Syndrome can occur when the patella underside becomes irritated by the way it tracks up and down as the knee is flexed and extended repetitively under stress (such as in running, cutting, jumping sports and activities). It has also been described as a tracking dysfunction—that is, the patella is having trouble with the way it tracks up and down in a groove of the femur, much like a train trying to stay on its train track. A dysfunction can occur from intrinsic and extrinsic factors, some of which are modifiable and some which are not—e.g., asymmetry of the quadriceps and hip strength, flat feet, wider pelvis, and overtraining.
Patellar articular cartilage when intact and healthy allows the patella to glide smoothly over the femur. If injured, damaged, or showing wear and tear, the cartilage may cause irritation in the joint leading to inflammation, pain and swelling. Articular cartilage injury may be a difficult condition to manage—there is no cure or one size fits all approach to an athlete with this condition in the anterior knee compartment.
That being said, there are options which may help improve comfort and function in the athlete–e.g. activity modification, physical therapy, anti-inflammatory medications, mechanical corrections, bracing, and judicious use of invasive interventions.
Tendonopathy (that is acute or chronic patella or quadriceps tendon injury), patella subluxation or dislocation (when the patella is displaced from its normal groove in the femur), and prepatellar or pes anserine bursitis (inflammation of fluid filled sacs around the knee) are all other common causes of anterior knee pain in an active person. Adolescent athletes—those who bones are still growing—can develop what some refer to as “growing pains”; usually these conditions are what sports medicine doctors call apophysitis, and this can occur in the distal patella (Sinding-Larsen- Johannson syndrome) and at the insertion of the distal patella tendon (Osgood Schlatter ’s disease).
Apophysitis occurs when the repetitive stress from sports or other activity is applied to a particular bone-tendon unit in the skeletally immature athlete, and overwhelms that particular area to heal itself. Some of the less non-traumatic common causes include soft tissue conditions such as plica syndrome (a fold of normal tissue that causes mechanical symptoms), and bony causes such as osteochondritis dissecans (injury to the bone causing focal necrosis) and a bipartite patella (a condition where the patella does not fully form during normal growth).
As with other musculoskeletal and sports medicine conditions, the overall goals in management of anterior knee pain are to improve comfort, restore function, maximize function, and to preserve function. Fortunately, most of the causes of anterior knee pain described above will never need surgery, nor is surgery the first step for nearly all of the conditions described.
As for when to seek professional help if you have anterior knee pain, consider it if you are experiencing: pain that is not relieved by over-the-counter medications such as ibuprofen; persistent pain not relieved by resting or modifying your activity; symptoms of swelling, buckling, painful catching, or night pain; symptoms with routine daily activities such as using the stairs or kneeling; and or symptoms that interfere with your expectations for sports, hobbies and exercise.
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