Histologic changes in the dog femur following total hip replacement with current cementing techniques

Histologic changes in the femurs of adult dogs were studied following total hip replacement using current cementing techniques. In the diaphyseal region, remodeling was initiated in the periosteum and progressed centripetally over 3 months. In the proximal (metaphyseal) region, remodeling was seen throughout the section by the second week. No fibrous membrane was formed at the bone-cement interface in the proximal region, and only isolated, non-progressive patches of fibrous membrane were formed in the distal region of the implant. The authors attribute the absence of membrane formation to careful preparation of the cement bed and use of pressurized cement injection. The exact congruence of vascularization and remodeling indicates a vascular etiology for the reaction of bone to cemented implantation. Vascular compromise at the time of operation leads to bone necrosis in the affected regions, and subsequent revascularization is a necessary precursor to bone remodeling. Thermal effects and monomer toxicity are considered unimportant.