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Objective

To radiographically evaluate periprosthetic femoral bone contrast and assess alignment of the prosthetic stem after uncemented and cemented total hip replacement (THR).

Study Design

Prospective clinical study.

Animals

Dogs (n = 15).

Methods

Dogs were classified into uncemented (n = 8) and cemented (n = 7) THR groups. Radiographs were analyzed using image processing software to evaluate femoral bone contrast (gray scale value, GV) for each and combined modified Gruen zone(s) immediately and 4 months after THR. Modified Gruen zones were classified into 5 zones to analyze retrospectively the regional radiographic GV of the femur around uncemented and cemented prosthetic stem. Alignment of prosthetic stem was assessed immediately and 4 months postoperatively. Variables were compared by use of 2-tailed t-test, with P < .05 considered significant.

Results

Zone 1 showed significant decrease in the mean bone GV 4 months after uncemented THR. No differences in zones 1–5 after 4 months of cemented THR. Combined zones showed significant decrease in overall mean bone GV 4 months after uncemented THR. No changes were observed 4 months after cemented THR. Number of limbs with varus-aligned femoral stem markedly increased after 4 months of uncemented THR.

Conclusions

Regional bone contrast and prosthetic stem alignment vary with the design of THR.