A nine-year-old boy with Henoch-Schönlein Purpura (HSP) presented with an arthropathy of the thoraco-lumbar spine. The boy played on a trampoline for several days before the onset of the low-back pain. The vascultic rash of HSP is recognized to be pressure-dependent. The authors speculate that the arthropathy of HSP is also pressure-dependent and that the low back pain in this patient was consequent to the preceding trampoline jumping.