Orthopedic implants: a guide to radiographic analysis.

Orthopedic technology is growing at a rapid rate. New implants reflect this technology whether it pertains to fracture fixation, joint replacement, spine stabilization, or soft-tissue reconstruction. This monograph is designed to assist both the radiologist and the orthopedist in accurately assessing plain radiographs of commonly used orthopedic implants. We discuss the biologic response of the surrounding bone to these devices; herein lies the key to understanding the radiographic presentation of these devices.

Detection of infection in loosened hip prostheses: efficacy of sonography.

OBJECTIVE: The purpose of this study was to determine the efficacy of sonography in the detection of infection in loosened hip prostheses. MATERIALS AND METHODS: The normal capsular morphology in 15 asymptomatic patients with total hip replacements was studied sonographically. Sonograms were then obtained in 33 patients who had pain in the hip after arthroplasty and radiologic findings of loosening of the prosthesis. These patients subsequently underwent aspiration and arthrography of the hip. Six of the 33 symptomatic patients proved to have prosthetic joint infection. RESULTS: On sonograms, the normal pseudocapsule is adherent to the proximal part of the anterior femoral cortex, and the capsule-to-bone distance is less than 3.2 mm (average, 2.6 mm). No hips with a capsule-to-bone distance less than 3.2 mm were infected. Sonograms in the six patients with infection showed marked intraarticular effusion with a mean capsule-to-bone distance of 10.2 mm. Five of these six had extracapsular fluid collections. Two patients with hip dislocations and four with aseptic loosening of the prosthesis had capsular distension on sonograms and cultures of aspirated material that showed no growth. CONCLUSION: Sonography can be used to diagnose infection around loosened hip prostheses. All patients who had an intraarticular effusion with extraarticular extension seen on sonograms had infection.

Complications associated with warfarin prophylaxis in total knee arthroplasty.

Systemic and local complications associated with the use of warfarin for deep vein thrombosis prophylaxis in total knee arthroplasty (TKA) are significant. Forty-seven patients with primary TKAs considered at high risk for developing thromboembolic disease were treated with a regimen of preoperative and postoperative warfarin. The incidence (n = 2) of systemic complications was 4%. The incidence (n = 6) of wound complications requiring specific treatment or discontinuing physiotherapy was 12%. In this series, wound complications did not jeopardize the end results of TKA. However, such wound complications as may have delayed recovery occurred with a frequency similar to that reported in other series of TKA using different antithromboembolic modalities.