RESUMO
Improvements in materials, components, and surgical techniques in cementless total hip arthroplasty are resulting in improved femoral stem fixation through bony ongrowth or ingrowth. While improved femoral stem fixation is one reason for the current excellent total hip survivorship, indications for stem removal such as infection, implant fracture, or osteolysis remain. A commonly used technique for fully ingrown femoral stems is an extended trochanteric osteotomy which can result in comminuted fractures of the proximal femur during stem removal requiring additional fixation. Therefore, a novel hip stem removal was developed to facilitate removal of these well-ingrown stems without the need for an extended trochanteric osteotomy. This study describes the removal system and surgical technique and presents a case series of successfully removed ingrown stems.
RESUMO
OBJECTIVE: To determine the ability of low- and conventional-dose computed tomography (CT) in identification of uric acid stones, which are of lower density than calcium oxalate stones. MATERIALS AND METHODS: Uric acid stones (3, 5, and 7 mm) were randomly placed in human cadaveric ureters and scanned using conventional 140-mAs and low-dose 70-, 50-, 30-, 15-, 7.5-, and 5-mAs settings. A single-blinded radiologist reviewed a total of 523 scanned stone images. Sensitivity and specificity were compared among different settings and stone sizes. RESULTS: Imaging using 140-, 70-, 50-, 30-, 15-, 7.5-, and 5-mAs settings resulted in 97%, 97%, 96%, 93%, 83%, 83%, and 69% sensitivity and 92%, 92%, 91%, 89%, 88%, 91%, and 94% specificity, respectively. There was a significant difference in sensitivity between 140 mAs and 15, 7.5, and 5 mAs (P = .011, P = .011, and P <.001, respectively). Sensitivity for 3-, 5-, and 7-mm stones was 83%, 90%, and 93%, respectively. At ≤ 15 mAs, 3-mm stones had a higher rate of false negatives (P <.001). CONCLUSION: Both low- and conventional-dose CTs demonstrate excellent sensitivity and specificity for the detection of ureteral uric acid stones. However, low-dose CT at ≤ 15 mAs resulted in reduced detection of uric acid stones.
