Pellegrini-stieda lesions in the pediatric population: A case series

Background: A Pellegrini-Stieda lesion is a calcified mass found in the region of the medial femoral condyle of the knee. It is thought to be post traumatic in origin and has classically been associated with injury to the medial collateral ligament (MCL). However, further studies have suggested variable origins of the lesion. The lesion itself is thought to be asymptomatic, with a small percentage of patients developing medial-sided knee pain or restricted range of motion, which is described as Pellegrini-Stieda disease (or syndrome). However, there is minimal literature regarding the significance of these lesions in the adult population and no published cases in the pediatric population. Due to the rarity and unknown significance, Pellegrini-Stieda lesions remain to be further elucidated in the pediatric population. Materials and methods: This is a retrospective case series of patients 18 years of age and under at a tertiary children's hospital diagnosed with a Pellegrini-Stieda lesion on imaging. Data regarding patient demographics, mechanism of injury, physical exam, radiographic findings, treatment, and outcomes were collected. Descriptive statistical analysis was conducted. Results: We identified 9 patients, (1 female, 8 male) with a documented Pellegrini-Stieda lesion on imaging (Figs. 1–5). The mean age was 16 years (13–18). All presented to the office or emergency room with a known injury or trauma – 5/9 (55.6%) occurred while engaging in competitive sports and 4/9 (44.4%) were involved in trauma. All but one patient (8/9; 88.9%) had an injury involving the MCL, with or without additional pathology (Table 1). The majority of patients (6/9; 66.7%) had no lesion present on initial imaging but did have a lesion on follow up radiographs or MRI. With regards to treatment, 5/9 (55.6%) required surgery for pathologies associated with the injury (Table 1). In terms of outcomes, 6/9 patients (66.7%) returned for follow up after treatment with an average follow up of 8.1 months (range 3–19 months). All 6 patients reported resolution of knee pain and return to full activities at the time of last follow up. Conclusions: Pellegrini-Stieda lesions in this pediatric case series were found after traumatic or sports related injuries. The lesions appeared radiographically in a delayed fashion. They were highly associated with MCL injury and other knee injuries which required surgical intervention. No patients developed symptomatic Pellegrini-Stieda syndrome after short-term follow up. This descriptive case series allows for a better understanding of the rare Pellegrini-Stieda lesion in the pediatric population.