Potential use of bisphosphonates in children with Legg–Calvé–Perthes disease with signs of osteoarthritis. Interim results from a single-center study

BACKGROUND: Legg–Calvé–Perthes disease is a multifactorial disease with a non-inflammatory and avascular mechanism of necrotic lesions. In some cases, children may have more aggressive disease with signs of osteoarthritis. This variant of Legg–Calvé–Perthes disease is characterized by active inflammation of the bone tissue and arthritis, often leading to severe deformity of the femoral head and early coxarthrosis. The problem of treating osteoarthritis in children with Legg–Calvé–Perthe disease is not solved due to the low effectiveness of non-steroidal anti-inflammatory drugs (NSAIDs). Osteoclast inhibition therapy with bisphosphonates in adults with idiopathic aseptic necrosis of the femoral head has been pathogenetically accepted. The use of bisphosphonates in children with Legg–Calvé–Perthe disease and osteoarthritis has not been evaluated. AIM: The aim of the study was to evaluate the efficacy and safety of bisphosphonates in children with Legg–Calvé–Perthes disease who presented with signs of osteoarthritis. MATERIALS AND METHODS: The study used data on the treatment of 14 children (mean age 7.5 ± 2.4 years, 71.4% girls) with Legg–Calvé–Perthe disease (at the impression fracture stage) and active hip osteoarthritis. All children had torpid arthritis refractory to NSAID therapy and present for at least 3 months. Treatment included ibandronic acid at 1.0 mg and 1.5 mg per infusion every 3 months in children younger than 7 years old and older than 7 years old, respectively. Five consecutive infusions were performed in the study. Treatment outcomes were assessed at 6, 12, and 18 months based on combined clinical, imaging, and laboratory changes. A modified SCORING OF HIP MRI FOR JIA score was used to assess osteoarthritis activity. RESULTS: All children showed a decrease in hip pain after the first infusion of ibandronic acid. The inactive phase of osteoarthritis during bisphosphonate treatment was achieved in 78.5% (11) of children after three consecutive infusions and in 21.5% (3) of children after four infusions. Post-infusion reactions were reported in 85.7% (12) of children during the initial phase of bisphosphonate treatment and were transient. Serum erythrocyte sedimentation rate, C-reactive protein, interleukin-6, and tumor necrosis factor-alpha levels were within reference ranges in children with osteoarthritis. Only 28.5% (4) of patients were found to have 25(OH)Vitamin D deficiency at the time of osteoarthritis diagnosis. CONCLUSIONS: The use of bisphosphonates in children with Legg–Calvé–Perthes disease and osteoarthritis can be considered an innovative pathogenetic treatment option. The data obtained suggest the potential for the use of bisphosphonates in children with Legg–Calvé–Perthes disease. Further follow-up of children in the study group is needed to assess long-term outcomes.