Arthroscopic Management of Pigmented Villonodular Synovitis of the Hip in Children and Adolescents

Background Pigmented villonodular synovitis (PVNS) is a benign proliferative synovial disorder most commonly described to affect the knee in adults. Literature describing PVNS in the pediatric population is limited to 2 small case series and a handful of single-patient case reports. Within these studies, only 2 patients with PVNS of the hip are described. Purpose To describe the presentation, management, and outcomes of a single-center series of pediatric patients with PVNS of the hip treated with arthroscopic synovectomy. Study Design Case series; Level of evidence, 4. Methods A retrospective review of consecutive pediatric patients treated for PVNS at a single institution was performed. Inclusion criteria consisted of patients younger than 19 years with surgically treated PVNS of the hip. Results Five pediatric patients with a mean age of 11.0 years were treated for PVNS of the hip from 2011 to 2016. The mean duration of symptoms from onset to surgical treatment was 247 days (range, 3-933 days). Upon review of magnetic resonance imaging (MRI) results, radiologists included PVNS in their differential in 3 patients. Seven surgeries were performed in 5 patients. All therapeutic procedures were arthroscopic synovectomies. Nodular PVNS was present in 4 patients, and diffuse disease was present in 1 patient. At a mean 32-month follow-up (range, 12-63 months), all patients were considered to be free of recurrence based on clinical examination and/or follow-up MRI. Four patients were asymptomatic and returned to all of their previous sports activities. Conclusion Young age at the time of diagnosis is a point to be highlighted in this cohort, and symptoms may be present for many months prior to diagnosis due to the failure to consider PVNS in children. Therefore, for patients with "atypical" presentations or lack of improvement with treatment for rheumatologic, bleeding, or infectious disorders, PVNS should be strongly considered. MRI with gradient echo sequences is the diagnostic imaging study of choice. One patient with diffuse involvement and preoperative degenerative changes showed progressive changes postoperatively. This type of PVNS may have a worse prognosis, but more diffuse cases are needed before the prognosis can be determined. Arthroscopic synovectomy following a timely diagnosis of PVNS produces good outcomes in nodular cases, with no evidence of symptomatic or radiographic disease persistence among these patients.