In 1913, anthropologist Ales Hrdlicka described a number of femora as having "mushroom heads," a deformity he attributed to arthritis deformans. The authors have attempted to define the cause of this condition.
Forty of 41 femora with "mushroom" femoral heads collected by Hrdlicka were grossly inspected and examined with plain radiographs and with computed tomography. Femoral neck angulation and degree of anteversion were determined.
Three distinct categories were established: group I, those specimens with normal angulation and short femoral necks; group II, those with varus angulation and short femoral necks; and group III, those with normal-sized femoral necks and normal femoral neck angulation. No correlation was found between degree of anteversion and the categories. Additionally, most of the mushroom deformities were related to osteophyte formation.
Most of the changes in the femora were the result of osteoarthritis. Two groups showed evidence of growth disturbances that occurred early in life. The changes in the second group were similar to those seen in Legg-Calvé-Perthes disease.