Inferior patellar pole fragmentation in children: just a normal variant?

BACKGROUND: Fragmentary ossification of the inferior patella is often dismissed as a normal variant in children younger than 10 years of age. OBJECTIVE: The purpose of this study was to determine whether fragmentary inferior patellar pole ossification is a normal variant or is associated with symptoms or signs of pathology using MRI and clinical exam findings as reference. MATERIALS AND METHODS: A retrospective review was performed on 150 patients ages 5-10 years who underwent 164 knee radiography and MRI exams (45.1% male, mean age: 7.8 years). The presence or absence of inferior patellar pole fragmentation on radiography was correlated with the presence or absence of edema-like signal on MR images. Clinical notes were reviewed for the presence of symptoms or signs referable to the inferior patellar pole. These data were compared with a 1:1 age- and sex-matched control group without inferior pole fragmentation. Statistical analysis was performed using two-tailed t-tests. RESULTS: Forty of 164 (24.4%) knee radiographs showed fragmentary ossification of the inferior patella. Of these 40 knees, 62.5% (25/40) had edema-like signal of the inferior patellar bone marrow compared with 7.5% (3/40) of controls (P = 0.035). Patients with fragmentary ossification at the inferior patella had a significantly higher incidence of documented focal inferior patellar pain compared with controls (20% vs. 2.5%, P = 0.015). CONCLUSION: Inferior patellar pole fragmentation in children 5 to 10 years of age may be associated with localized symptoms and bone marrow edema-like signal and should not be routinely dismissed as a normal variant of ossification.

Magnetic resonance imaging of the long bones of the upper extremity.

The long bones of the upper extremity are often overlooked in favor of addressing their intervening joints. However, there are a wide variety of pathologic processes that can involve these anatomic segments. To better understand the complex anatomy of the upper extremity, this article is divided into sections describing the osseous, muscular, and neurovascular anatomy of the arm and forearm using a compartmental approach. The discussion touches on a few common normal variants and their potential functional consequences. The upper extremity joints of the shoulder, elbow, and wrist are addressed separately.