Patellofemoral pain syndrome is pain behind the kneecaps (patella). It results from damage to the cartilage that cushions the kneecap. It arises in the young from strenuous exercise and in the old from arthritis. If the cause is not arthritic, it is reversible. The solution is to rest, to address muscle imbalance, to support weak arches and to avoid exposure to the cold.
Terminology
Patellofemoral pain syndrome more commonly goes by the name chondromalacia patella. The femur in the name refers to the thighbone. The shinbone, or tibia, is the main lower bone that the patellar tendon connects to the front thigh muscles, or quadriceps. The vastus medialis is the inner quadriceps muscle responsible for a subtle arc the kneecap traces (if healthy) during muscle contraction.
The Link Between Pain Under the Kneecap and Cartilage Damage
Patellofemoral pain syndrome refers to pain under the kneecap (patella) from irritation of the patellar tendon. The kneecap travels over cartilage that smoothes its path. Irritation to the back of the kneecap results when the cartilage is rough from damage. The cartilage can be damaged from overuse and arthritis, but the main reason is mal-tracking of the patella.
Differential Diagnosis
Patellofemoral pain feels similar to two other kinds of knee pain: tears in the cartilage that cushions the tibia against the femur (meniscus) and patellar tendonitis. Surgery aside, the treatment of patellar tendonitis and patellofemoral pain is the same. Therefore, a differential diagnosis between the two isn't necessary until surgery is considered.
Mal-tracking
In non-arthritic cases, mal-tracking of the patella is the main source of chondromalacia patella, pushing the cartilage out of its natural position. To maximize strength, tendons and cartilage have a low density of blood vessels. The downside is that they are not only slow to heal but also colder than the rest of the leg. This makes them more brittle than the muscle pulling and pushing them. Sources of mal-tracking include muscle imbalance, tight muscles and foot pronation.
Corrections
The main strategy of treatment is to eliminate the mal-tracking of the patella. Any one of the following may be needed: orthotic shoe inserts, as if to straighten a load-bearing column; stretching the hamstrings and outside quadriceps; strengthening the hip muscles with leg lifts; and strengthening the inner quadriceps (vastus medialis) with slow, medium-weight leg extensions. The correction to cold exposure is to cover up the knee with fleece or neoprene if necessary.
