Patellofemoral Malalignment in Adolescents: Computerized Tomographic Assessment with or without Quadriceps Contraction

Twenty-seven adolescents with anterior knee pain with or without patellar instability were studied by comput erized tomography to detect patellofemoral malalign ment. The examination was performed with and without quadriceps contraction with the knee flexed to 15°. Con gruence angle, patellar tilt angle, sulcus angle, and trochlear depth were measured. This investigation showed the well-known types of patellofemoral mal alignment with quadriceps relaxed (tilted, lateralized, lateralized, and tilted patella) and, in 52% of cases, re vealed changes in type and severity with quadriceps contraction (in 41 %, lateralization and tilting were mark edly more evident; in 11 %, the type of malalignment changed). The results demonstrate that, in addition to assessment with quadriceps relaxed, computerized to mography with quadriceps contraction is a useful ad junct to diagnose and define the type of malalignment in particularly difficult circumstances.