The right leg x-ray shows alternating sclerotic and lucent bands in the distal femoral and upper tibial metaphyseal areas. This is the ‘Zebra Stripe Sign’ which is related to cyclical pamidronate therapy. Cyclical administration of pamidronate (bisphosphonate) promotes dense bone formation resulting in alternating dense and lucent bands in the metaphysis.

Reference: Pediatric Imaging, A Teaching File, Thapa & Weinberger, 2013 Edition.