RESUMEN
BACKGROUND: Abnormal torsion of the femur is correlated to lower extremity pathologies. Although computed tomography (CT) scan is the gold standard torsional measurement, magnetic resonance imaging (MRI) is proposed as a viable alternative. Our aim was to determine the accuracy and consistency of MRI and CT femur rotational studies based on 4 described protocols. METHODS: Twelve cadaveric femora were stripped of soft tissue before imaging and physical assessment of torsion. Four advanced imaging series were obtained for each specimen: CT with axial cuts of the femoral neck (CT-axial); CT with oblique cuts of the femoral neck (CT-oblique); MRI with axial cuts of the femoral neck (MR-axial); MRI with oblique cuts of the femoral neck (MR-oblique). Anatomic specimens were placed with the posterior femoral condyles flat on a dissection table for assessment of true torsion with digital images. Three independent reviewers performed all measurements, including true torsion, using imaging software. Bland-Altman analysis was repeated with the data from each reviewer. RESULTS: Interobserver repeatability for all groups was high at 0.95, 0.87, 0.90, 0.97, and 0.92 for CT-axial, CT-oblique, MR-axial, MR-oblique, and true torsion, respectively. CT-axial had the lowest mean difference from clinical imaging for all three observers (all <1 degree) and held the tightest 95% limits of agreement for 2/3 observers. As torsion increases from neutral, MR-oblique linearly overestimates the rotation compared with true torsion. CT-oblique and MR-axial showed slightly greater differences from true torsion compared with CT-axial, but did not reach clinical significance. CONCLUSIONS: CT-axial was both most accurate and reproducible when compared with true torsion of the femur and should be the gold standard imaging modality; however, both MR-axial and CT-oblique were accurate to a level that is likely less than clinical significance. MR-axial images should be used in clinical situations where radiation exposure needs to be limited. MR-oblique images can overestimate true antetorsion and should not be used. CLINIC SIGNIFICANCE: CT-axial followed by MRI-axial is the most accurate and consistent in measuring true torsion of the femur.
Asunto(s)
Cuello Femoral/diagnóstico por imagen , Fémur , Imagen por Resonancia Magnética , Tomografía Computarizada por Rayos X , Anomalía Torsional/diagnóstico por imagen , Fémur/diagnóstico por imagen , Humanos , Articulación de la Rodilla , Reproducibilidad de los Resultados , Rotación , Anomalía Torsional/patologíaRESUMEN
Piriformis syndrome is the compression or the irritation of the sciatic nerve by the adjacent piriformis muscle in the buttock leading to symptoms that include buttock pain, leg pain, and altered neurology in the sciatic nerve distribution. Epidemiological figures of the prevalence are unknown, but are estimated to be about 12.2% to 27%. There is no consensus on the diagnostic criteria. Advancement in magnetic resonance imaging allows us to observe unilateral hyperintensity and bowing of the sciatic nerve. The pathophysiology of the disease includes single blunt trauma, overuse causing piriformis hypertrophy, and long-term microtrauma causing scarring. Treatments include physiotherapy, steroid injections, and surgery. Minimally invasive techniques are emerging with the hope that with less postoperative scar tissue formation, there will be less recurrence of the disease. In this chapter, senior author describes his technique for endoscopic sciatic neurolysis.