Anterior knee pain is common during the second decade and may occur in up to a third of adolescents. This pain may be associated with some underlying patellofemoral malalignment or may be idiopathic, occurring in normal individuals.
Structural Anterior Knee Pain
Pain associated with some knee dysplasia is more serious and often requires operative correction.
Evaluation Identify the underlying dysplastic features, such as lateral tibial torsion, genu valgum, patella alta, quadriceps hypoplasia, lateral tether, shallow sulcus, or excessive joint laxity. Consider imaging the patellofemoral joint with a CT scan to rule out patellar malpositioning.
Management Manage first with NSAIDS and isometric exercises. During the first visit, introduce the possible need for a realignment procedure. Identify and, if possible, quantitate the severity of each dysplastic feature. Correct obvious manageable deformities early. In other cases, the decision is difficult. For example, bilateral double-level osteotomies are necessary to correct severe rotational malalignment. Thoughtfully place the operative incision.
Idiopathic Anterior Knee Pain
This pain is common among teenagers, especially girls, and is often associated with a period of rapid growth. The pain is often activity related, is poorly localized, and may cause disability. It has been described as the headache of the knee. About one-third of these patients have features of the MMPI found in individuals with nonorganic back pain. Its natural history is one of spontaneous improvement over a period of years.
Diagnosis This pain involves a history of discomfort after sitting; pain with exercise, walking down stairs, or with sitting and squatting; a crunching sound with walking up stairs; and/or a sense of giving way with jumping or running. Often it is most prominent in the morning or after sitting and improves with time and warm up. When asked to localize the pain, the patient will often grab the entire front of the knee (grab sign).
Cause The causes are numerous and often associated with muscle imbalance. Aggravating factors may be poor training and shoeware.
Treatment Prescribe NSAIDS, isometric exercises, activity modification, and reassurance. Sometimes applying ice reduces discomfort. Sometimes a knee sleeve with a patellar cutout seems to help. Avoid arthroscopy and lateral release procedures.
Rehabilitation After the acute phase has passed, the patient should establish flexibility and strength before gradually resuming full activity. Stretching should be painfree.
Prevention Suggest warm up and stretching before activity, and avoiding activities that cause pain. This may require modification of activities by substituting others that are less stressful for the knee.