A study of the bone-cement interface in upper limb prostheses not subjected to loading.

The appearance of a radiolucent band at the cement-bone interface is a frequent finding in lower limb prostheses. This is still a controversial subject, but almost certainly has a multifactorial basis. Stress related to loading may be one of the causal factors. The authors therefore studied the evolution and behaviour of this radiolucent line at the bone-cement interface in 31 upper limb prostheses not subjected to significant loading or stress. These were special prostheses designed to replace the upper humerus after the radical excision of bone tumours. The development of a radiolucent band was not significantly different from the usual conditions in which loading is present but in our cases it was nonprogressive and there was never any evidence of loosening of the prosthesis.