Screw Placement After Pinning of Slipped Capital Femoral Epiphysis
Autor: | Phil Blyth, Ngaire Susan Stott, Suren Senthi, Russell Metcalfe |
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Rok vydání: | 2011 |
Předmět: |
Male
musculoskeletal diseases medicine.medical_specialty Radiography Bone Screws Bone Nails Femoral head Screw thread Epiphyses Slipped Humans Medicine Orthopedics and Sports Medicine Prospective Studies Child business.industry Femur Head General Medicine Anatomy medicine.disease medicine.anatomical_structure Epiphysiolysis Coronal plane Pediatrics Perinatology and Child Health Orthopedic surgery Female Tomography Tomography X-Ray Computed business Slipped capital femoral epiphysis |
Zdroj: | Journal of Pediatric Orthopaedics. 31:388-392 |
ISSN: | 0271-6798 |
Popis: | Background: Unrecognized pin penetration in the treatment of slipped capital femoral epiphysis has serious long-term sequelae. The purpose of this study was to use postoperative computerized tomographic (CT) scans to determine the true position of the screw tip when compared with standard radiograph views. Methods: Twenty-four patients with 33 slipped capital femoral epiphyses were included in the study. Intraoperative or postoperative radiographs [anteroposterior (AP) and frog lateral] were compared with postoperative CT scans (coronal and axial) to determine (1) distance of the screw tip from the subchondral bone of the femoral head, (2) the number of screw threads across the physis, and (3) the 3-dimensional placement of the screw tip in the femoral head. Results: The positions of 38 screws in 33 hips were assessed. Screw position within specific quadrants of the femoral head was more anterior and superior than appreciated on radiographs. AP radiographs overestimated the distance between the screw tip and the subchondral bone, the average distance being 5.5mm on AP radiographs and 3.4mm on coronal CT (P < 0.0001). Bland-Altman analysis confirmed 95% limits of agreement of ― 5.6 to 1.5 mm, indicating that screws could be up to 5.6 mm closer to the subchondral bone than estimated by the AP radiograph. Closer agreement was found between the frog lateral radiograph and the axial CT views, with the distance from the subchondral bone averaging 4.7mm on frog lateral radiographs and 4.1 mm on axial CT (P < 0.01). Bland-Altman analysis showed 95% limits of agreement between the 2 measures of — 3.5 to 2.3 mm, suggesting that some screws were up to 3.5 mm closer to the subchondral bone. Three more anteriorly placed screws seemed to penetrate subchondral bone on CT, findings not shown on standard radiographs. Conclusions: Frog lateral radiographs of the hip provide a more accurate estimation of screw placement than AP radiographs. Screws closer than 4 mm to the subchondral bone on frog lateral radiographs or 6 mm on AP radiographs may penetrate subchondral bone. |
Databáze: | OpenAIRE |
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