PERIPROSTHETIC BONE REMODELING AFTER CEMENTLESS TOTAL HIP-REPLACEMENT- A PROSPECTIVE COMPARISON OF 2 DIFFERENT IMPLANT DESIGNS

In a prospective study of 14 patients undergoing total hip replacement we have used dual-energy X-ray absorptiometry (DEXA) to investigate r emodelling of the bone around two different designs of cementless femo ral prosthesis, The bone mineral density (BMD) was measured at 12-week ly intervals for a year. Eight patients (group 8) had a stiff, collarl ess implant and six (group B) a flexible isoelastic implant. Patients in group A showed a decrease in BMD from 14 weeks after operation, By 12 months, the mean loss in BMD was 27%, both medially and laterally t o the proximal part of the implant. Those in group B showed an overall increase in BMD which reached a mean of 12.6% on the lateral side of the distal portion of the implant. Our results support the current con cepts of the effects of stem stiffness and flexibility on periprosthet ic remodelling.