We studied five skeletally immature patients who had a cemented
endoprosthetic replacement involving the proximal part of the tibia because
of a malignant tumor. In each patient, the cement-column fractured,
allowing additional physeal growth. With plain radiographs and scanograms,
we determined the cross-sectional areas of the physes, the cement-mantle,
and the tibial component. Using the known tensile strength of
polymethylmethacrylate cement, we then calculated the minimum force that
the growth plates must have overcome to fracture the cement. This averaged
584 newtons per square centimeter. This observation of continued tibial
growth after partial physeal ablation with a cemented prosthesis in
skeletally immature patients presented a unique opportunity to estimate the
force generated in the human physis during growth.