MIAMI — Patellofemoral pain syndrome is the most common sports-related overuse injury in young athletes, occurring in an estimated 30%–40% of female athletes at some point in their career, Dr. Joseph Congeni said at a meeting on pediatric sports medicine sponsored by the American Academy of Pediatrics.
Athletes need to understand the process of PFS and how it is treated, rather than play through their pain or stop sports altogether without seeking treatment.
The syndrome, also known as runner's knee, is usually caused by improper tracking of the kneecap in the patellofemoral groove. A few cases do not involve tracking but result from compression of the kneecap, which can develop if the hamstring muscle is significantly stronger than the quadriceps. This type of PFS more often occurs in younger children who have just gone through their growth spurt or teenage boys.
The incidence of tracking PFS is about five times greater in girls than in boys. Several anatomical factors contribute to PFS, including femoral anteversion, kneecaps pointing toward each other (“squinting patella”), genu varum (bowleg), and tibia varum. The feet compensate for the malalignment by pronating, and these factors together result in pain, said Dr. Congeni, medical director of the sports medicine center at the Children's Hospital Medical Center of Akron (Ohio).
Chronic overuse injuries like PFS can be more difficult to diagnose and treat than are acute injuries. Many factors are at play, including anatomy, biomechanics, hormonal issues, nutrition, genetics, training errors, and micro- and macrotrauma.
Children with tracking PFS present with pain around the knee that emerges gradually without any specific injury. They may or may not have swelling around the kneecap. Clinicians may see that the patella tracks in a “J” pattern when the leg is extended, because the patella moves inward as it moves up along the knee. Increased ligament laxity or instability also is common in these patients.
The functional tests of a minisquat and a catcher's squat, which will likely be painful in PFS, can help in the diagnosis.
Aside from having a thorough patellar exam, athletes with suspected PFS should undergo a full structural exam—including a careful examination of the hip—to rule out a slipped capital femoral epiphysis (SCFE). Dr. Congeni recommended, at the very least, clinical evaluation of the internal and external rotation of the hip in these children, as vague knee pain is one of the signs of SCFE. “This is a problem where kids sometimes walk with a limp the rest of their life if we miss it,” he said.
PFS is usually a straightforward clinical diagnosis based on history and physical exam, and does not require additional tests. Dr. Congeni recommended x-rays for children who do not improve after a month to rule out other causes and to assess the state of the kneecap.
Dr. Congeni explained that the clinical course of PFS is likely to be a roller coaster of good and bad days, weeks, or months, as activity levels change. Sitting for long periods and walking on stairs or hills can aggravate symptoms.
Treating PFS is a slow process that involves rest and rehabilitation through strengthening (quadriceps and gluteals) and increasing flexibility (quadriceps, hamstrings, and iliotibial band). Bracing can provide some help through a short-term situation. Orthotics can be helpful for correcting mechanical issues, and Dr. Congeni is moving toward orthotics and away from bracing when treating athletes with PFS in his own practice.
He also suggested asking about the use of nonsteroidal anti-inflammatory drugs. The first goal of treatment in those patients is to help reduce and eventually discontinue the use of these medications.
Many athletes with the syndrome have a high-riding kneecap, as shown above. Courtesy Dr. Joseph Congeni