Introduction: Perthes disease (PD), idiopathic femoral head avascular necrosis, often results in deformity. The underlying cause is unclear and long-term function is directly related to the roundness of femoral head. Current treatment include mechanical treatments and various surgical procedures, which are therapeutic but cant prevent collapse. A multicentre, prospective, randomised controlled trial of 12 months zoledronic acid (ZA) in children with PD was conducted. We hypothesized that by inhibiting osteoclastic resorption, ZA could maintain femoral head strength and shape at 24 months.
Methods: Inclusion criteria were >5 y/o, acute onset and unilateral PD. The primary outcome measure was deformity index (DI) at 24 months. Secondary outcome measures were femoral head subluxation (extrusion index), FACES pain scale, non-arthritic hip score (NAHS) and Global Paediatric Outcome Data collection instrument (PODCI). The patients were randomised into two treatment arms: a) Standard care or b) Zoledronic acid and standard care. Safety parameters included bone densitometry (DXA) and mineral homeostasis.
Results: Seventy-eight patients (mean age 7.84y±1.64) were evaluated. At 12 months, DI measurements on pelvic radiograph showed no difference between the two groups. All participants showed significant improvement of range of motion over 2 years (P<0.05), but was comparable between groups. Patients in the treatment group reported better pain relief as evidenced by FACES pain scale and the pain component of PODCI (P<0.05). DXA results revealed significant increment following 12 month of ZA. Following completion of trial at 24 months, DI measurements again showed no difference (P=0.54). The same findings were found for extrusion index (P=0.82). Hip range improved further, with significantly improved abduction in the treatment group (P<0.05). However, hip pain was no longer significantly decreased at this juncture. Otherwise, biochemical markers of bone turnover were within normal range. There were no reports of fracture, spondylolisthesis or osteonecrosis of jaw.
Conclusion: Bone density was significantly increased following treatment with ZA, although within the reported range in previous studies. With this clinically-safe dosage, the treatment of children with PD utilizing ZA may provide early pain relief and subsequent improvement in hip range of motion, but does not prevent femoral head deformity.
Disclosure: Partial funding for study from Novartis.