Denosumab and surgery for the treatment of Perthes’ disease in a 9-year-old boy: favorable course documented by comprehensive imaging— a case report

© 2017 The Author(s). Published by Taylor & Francis on behalf of the Nordic Orthopedic Federation. This is an Open Access article distributed under the terms of the Creative Commons Attribution-Non-Commercial License (https://creativecommons.org/licenses/by-nc/3.0) DOI 10.1080/17453674.2017.1298020 A boy aged 9 years and 4 months developed a recurrent rightsided limp. His father, a radiologist, prompted a contrast magnetic resonance imaging (MRI) after 6 weeks and diagnosed early Perthes’ disease (Figure 1). There were risk factors for a poor prognosis. The boy was relatively old for Perthes’ disease. He was a physically active child of small stature with uncertain compliance for nonweight bearing. Disseminated epiphyseal signal alterations in MRI suggested total involvement, Catterall group 4 (Catterall 1971). 2 weeks later, a posteromedial epiphyseal-metaphyseal cyst was seen. At a new examination another 2 weeks later, radiographs and MR images showed a subchondral fracture, but the epiphysis was not sclerotic (Figure 2). The disease was in early stage Ia according to the modifi ed Waldenström classifi cation (Joseph et al. 2003, Hyman et al. 2015). Owing to the risk of a severe course, we suggested early containment surgery. The family, however, opted for a mainly conservative treatment with close follow-up by MRI. Thus, treatment consisted of minimal weight bearing by use of crutches or a wheelchair. At 5 months after onset, there was still no sclerosis or significant extrusion in radiographs. However, a slight reduction in epiphyseal height and some anterior fl attening indicated stage Ib. The subchondral fracture now involved slightly more than 50% of the epiphysis. A simultaneous contrast MRI showed complete lack of perfusion in the center, a small area of hyperperfusion laterally, persistence of the epiphyseal-metaphyseal cyst posteromedially, and marked synovitis (Figure 3), all suggesting a worsening hip. The family decided to resort to anti-resorptive treatment. A dose of 60 mg denosumab was administered. At 11.5 months, an MRI showed stage IIb with signs of beginning of loss of containment (Meiss 2001) (Figure 4). We strongly advised surgery. Further application of denosumab was not considered. 1 year after onset and 7 months after the denosumab injection, radiographs showed atypical re-ossifi cation with a centrolateral density (stage IIIa), moderate extrusion, a faint, radiolucent metaphyseal band, and major anterior fl attening (Figure 5). 1 month later, a varus osteotomy of the Figure 1. At 6 weeks. MRI (A) and contrast MRI (B). Prior to stage Ia. A B